NOBLE DRILLING CORP
S-4, 1994-07-08
DRILLING OIL & GAS WELLS
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<PAGE>   1
 
      AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JULY 8, 1994
 
                                                       REGISTRATION NO. 33-
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                             ---------------------
                                    FORM S-4
            REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933
                             ---------------------
                           NOBLE DRILLING CORPORATION
             (Exact name of registrant as specified in its charter)
 
<TABLE>
<S>                                 <C>                                 <C>
              DELAWARE                              1381                             73-0374541
  (State or other jurisdiction of       (Primary Standard Industrial              (I.R.S. Employer
   incorporation or organization)       Classification Code Number)             Identification No.)

                                                                         JAMES C. DAY
                                                        CHAIRMAN, PRESIDENT AND CHIEF EXECUTIVE OFFICER
          10370 RICHMOND AVENUE, SUITE 400                        NOBLE DRILLING CORPORATION
                HOUSTON, TEXAS 77042                           10370 RICHMOND AVENUE, SUITE 400
                   (713) 974-3131                                    HOUSTON, TEXAS 77042
 (Address, including zip code, and telephone number,                    (713) 974-3131
   including area code, of registrant's principal      (Name, address, including zip code, and telephone
                  executive offices)                  number, including area code, of agent for service)
</TABLE>
 
                             ---------------------
                                   Copies to:
 
<TABLE>
<S>                                                  <C>
                 ROBERT D. CAMPBELL                                  KEITH R. FULLENWEIDER
                 THOMPSON & KNIGHT,                                 VINSON & ELKINS L.L.P.
             A PROFESSIONAL CORPORATION                              2500 FIRST CITY TOWER
           1700 PACIFIC AVENUE, SUITE 3300                                1001 FANNIN
                 DALLAS, TEXAS 75201                               HOUSTON, TEXAS 77002-6760
                   (214) 969-1700                                       (713) 758-2222
</TABLE>
 
                             ---------------------
     APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC: Upon the
effective date of the Merger described in this Registration Statement.
                             ---------------------
     If the securities being registered on this Form are being offered in
connection with the formation of a holding company and there is compliance with
General Instruction G, check the following box. / /
                             ---------------------
                        CALCULATION OF REGISTRATION FEE
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 
<TABLE>
<CAPTION>
                                                                   PROPOSED        PROPOSED
                                                    AMOUNT         MAXIMUM          MAXIMUM        AMOUNT OF
             TITLE OF EACH CLASS OF                  TO BE      OFFERING PRICE     AGGREGATE      REGISTRATION
          SECURITIES TO BE REGISTERED             REGISTERED      PER SHARE     OFFERING PRICE        FEE
<S>                                                <C>              <C>            <C>                <C>
- ---------------------------------------------------------------------------------------------------------------
Common Stock, par value $.10 per share..........   28,844,280(1)    $ 5.5625(2)    $160,446,307(2)    $ 55,326
- ---------------------------------------------------------------------------------------------------------------
Common Stock, par value $.10 per share..........      480,000(3)    $ 7.8750(4)    $  3,780,000(4)    $  1,303
- ---------------------------------------------------------------------------------------------------------------
$1.50 Convertible Preferred Stock, par value
  $1.00 per share...............................    4,025,000(5)    $23.0625(6)    $ 92,826,562(6)    $ 32,009
- ---------------------------------------------------------------------------------------------------------------
Common Stock, par value $.10 per share..........           --(7)          --               --           None
- ---------------------------------------------------------------------------------------------------------------
          TOTAL.................................                                   $257,052,869       $ 88,638
</TABLE>
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 
(1) Consists of (a) 28,598,835 shares of Noble Common Stock issuable upon the
    conversion pursuant to the Merger of currently outstanding shares of Chiles
    Common Stock and (b) 245,445 shares of Noble Common Stock issuable upon the
    conversion pursuant to the Merger of shares of Chiles Common Stock that may
    be issued prior to consummation of the Merger pursuant to the exercise of
    currently outstanding Chiles Options.
(2) Estimated solely for the purpose of determining the registration fee
    pursuant to Rule 457(f), based on the average of the high and low sales
    prices for Chiles Common Stock on the American Stock Exchange on June 30,
    1994.
(3) Consists of shares issuable pursuant to the Merger in exchange for and upon
    the cancellation of currently outstanding Chiles Options.
(4) Estimated solely for the purpose of determining the registration fee
    pursuant to Rule 457(c), based on the average of the high and low sales
    prices for Noble Common Stock in the NASDAQ National Market System on June
    30, 1994.
(5) Consists of shares issuable upon the conversion pursuant to the Merger of
    currently outstanding shares of Chiles Preferred Stock.
(6) Estimated solely for the purpose of determining the registration fee
    pursuant to Rule 457(f), based on the average of the high and low sales
    prices for Chiles Preferred Stock on the American Stock Exchange on July 1,
    1994.
(7) Represents an indeterminable number of shares of Noble Common Stock issuable
    (a) upon the conversion pursuant to the Merger of shares of Chiles Common
    Stock that may be issued prior to the consummation of the Merger pursuant to
    the conversion of currently outstanding shares of Chiles Preferred Stock in
    respect of which shares of Noble Common Stock no registration fee is being
    paid because it is being paid in respect of the shares of Noble $1.50
    Convertible Preferred Stock registered hereunder, and (b) from time to time
    upon conversion of the Noble $1.50 Convertible Preferred Stock in respect of
    which shares of Noble Common Stock no registration fee is required pursuant
    to Rule 457(i) because such shares will be issued for no additional
    consideration.
                             ---------------------
     THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL
FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(a) OF
THE SECURITIES ACT OF 1933 OR UNTIL THIS REGISTRATION STATEMENT SHALL BECOME
EFFECTIVE ON SUCH DATE AS THE COMMISSION, ACTING PURSUANT TO SAID SECTION 8(a),
MAY DETERMINE.
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>   2
 
                           NOBLE DRILLING CORPORATION
 
                             CROSS-REFERENCE SHEET
                   PURSUANT TO ITEM 501(b) OF REGULATION S-K
 
<TABLE>
<CAPTION>
ITEM
NO.                      ITEM IN FORM S-4                      LOCATION OR HEADING IN PROSPECTUS
- ----  ------------------------------------------------------   ---------------------------------
<S>   <C>                                                      <C>
               A. INFORMATION ABOUT THE TRANSACTION
 1.   Forepart of Registration Statement and Outside Front
      Cover Page of Prospectus..............................   Outside Front Cover Page
 2.   Inside Front and Outside Back Cover Pages of
      Prospectus............................................   Available Information; Table of
                                                                 Contents
 3.   Risk Factors, Ratio of Earnings to Fixed Charges and
      Other Information.....................................   Outside Front Cover Page;
                                                                 Summary; Investment
                                                                 Considerations
 4.   Terms of the Transaction..............................   Summary; The Merger; Certain
                                                                 Provisions of the Merger
                                                                 Agreement
 5.   Pro Forma Financial Information.......................   Summary; Unaudited Pro Forma
                                                                 Combined Financial Statements
 6.   Material Contacts With the Company Being Acquired.....   Investment Considerations; The
                                                                 Merger
 7.   Additional Information Required For Reoffering by
      Persons and Parties Deemed to be Underwriters.........   Not applicable
 8.   Interests of Named Experts and Counsel................   Not applicable
 9.   Disclosure of Commission Position on Indemnification
      for Securities Act Liabilities........................   Not applicable

               B. INFORMATION ABOUT THE REGISTRANT
10.   Information With Respect to S-3 Registrants...........   Incorporation of Certain
                                                                 Documents by Reference; The
                                                                 Companies
11.   Incorporation of Certain Information by Reference.....   Incorporation of Certain
                                                                 Documents by Reference
12.   Information With Respect to S-2 or S-3 Registrants....   Not applicable
13.   Incorporation of Certain Information by Reference.....   Not applicable
14.   Information With Respect to Registrants Other than
      S-3 or S-2 Registrants................................   Not applicable

         C. INFORMATION ABOUT THE COMPANY BEING ACQUIRED
15.   Information With Respect to S-3 Companies.............   Incorporation of Certain
                                                                 Documents by Reference; The
                                                                 Companies
16.   Information With Respect to S-2 or S-3 Companies......   Not applicable
17.   Information With Respect to Companies Other than
      S-3 or S-2 Companies..................................   Not applicable
</TABLE>
<PAGE>   3
 
<TABLE>
<CAPTION>
ITEM
NO.                      ITEM IN FORM S-4                      LOCATION OR HEADING IN PROSPECTUS
- ----  ------------------------------------------------------   ---------------------------------
<S>   <C>                                                      <C>
               D. VOTING AND MANAGEMENT INFORMATION
18.   Information if Proxies, Consents or Authorizations Are
      to be Solicited.......................................   Notice of Meetings; Outside Front
                                                                 Cover Page; Summary; The
                                                                 Meetings; The Merger; Certain
                                                                 Provisions of the Merger
                                                                 Agreement; Comparison of
                                                                 Stockholder Rights
19.   Information if Proxies, Consents or Authorizations Are
      Not to be Solicited or in an Exchange Offer...........   Not applicable
</TABLE>
<PAGE>   4
 
                           NOBLE DRILLING CORPORATION
 
                        10370 RICHMOND AVENUE, SUITE 400
                              HOUSTON, TEXAS 77042
 
                                 August  , 1994
 
To Our Stockholders:
 
     You are cordially invited to attend a Special Meeting of Stockholders of
Noble Drilling Corporation ("Noble") at                 ,           , Houston,
Texas, on       , September   , 1994, at 10:00 a.m., local time.
 
     At the Special Meeting, stockholders will be asked to approve a merger
proposal (the "Merger Proposal"). The Merger Proposal includes approval of a
merger agreement pursuant to which Chiles Offshore Corporation ("Chiles") would
merge into a newly formed, wholly owned subsidiary of Noble. The merger
agreement provides that, upon consummation of the merger, each issued and
outstanding share of common stock of Chiles would be converted into the right to
receive 0.75 of a share of Noble common stock and each issued and outstanding
share of $1.50 convertible preferred stock of Chiles would be converted into the
right to receive one share of a new series of $1.50 convertible preferred stock
of Noble. The new series of Noble preferred stock will have substantially the
same rights, privileges, preferences and voting power as the Chiles preferred
stock.
 
     Noble does not currently have available enough authorized shares of common
stock to permit it to consummate the merger. Thus, the merger cannot be
consummated unless Noble's certificate of incorporation is amended to increase
the authorized shares of Noble common stock. At the Special Meeting,
stockholders will also be asked to approve a proposal to amend Noble's
certificate of incorporation to increase the number of authorized shares of
Noble common stock from 75,000,000 to 200,000,000. The Merger Proposal and the
proposed charter amendment are described more fully in the accompanying Joint
Proxy Statement/Prospectus.
 
     YOUR BOARD OF DIRECTORS BELIEVES THAT THE MERGER PROPOSAL AND THE PROPOSED
CHARTER AMENDMENT, WHICH WERE APPROVED UNANIMOUSLY BY THE BOARD, ARE IN THE BEST
INTERESTS OF THE STOCKHOLDERS OF NOBLE AND RECOMMENDS THAT YOU VOTE FOR THE
MERGER PROPOSAL AND CHARTER AMENDMENT. In addition, the Board of Directors has
received the opinion of Simmons & Company International, financial advisor to
Noble, that the consideration to be paid by Noble in the merger is fair from a
financial point of view to the holders of Noble common stock and $2.25
convertible exchangeable preferred stock. A copy of the opinion is included in
the Joint Proxy Statement/Prospectus as Appendix II thereto. Approval of the
Merger Proposal requires the affirmative vote of the holders of a majority of
the outstanding shares of Noble common stock present and entitled to vote
thereon at the Special Meeting. Approval of the Merger Proposal will constitute
approval of the merger agreement and the issuance of shares of Noble common
stock and the new series of Noble preferred stock pursuant to the merger.
Approval of the proposed charter amendment requires the affirmative vote of the
holders of a majority of the shares of Noble common stock outstanding and
entitled to vote at the meeting.
 
     At the Special Meeting, stockholders will also be asked to approve a
proposal to amend the Noble Drilling Corporation 1991 Stock Option and
Restricted Stock Plan to increase from 1,900,000 to 5,200,000 the number of
shares of Noble common stock available for issuance thereunder and to make
certain amendments to conform with recent changes in federal tax laws. Approval
of the proposed stock option plan amendments requires the affirmative vote of
the holders of a majority of the outstanding shares of Noble common stock
present and entitled to vote thereon at the meeting.
 
     You are urged to read carefully the Joint Proxy Statement/Prospectus and
the Appendices thereto in their entirety for a complete description of the
Merger Proposal and the proposed charter and stock option plan amendments.
Whether or not you plan to be at the Special Meeting, please be sure to sign,
date and return the enclosed proxy or voting instruction card in the enclosed
envelope as promptly as possible so that your shares may be represented at the
Special Meeting and voted in accordance with your wishes. Your vote is important
regardless of the number of shares you own.
 
                                            Sincerely,
 
                                            JAMES C. DAY
                                            Chairman, President and Chief
                                            Executive Officer
<PAGE>   5
 
                          CHILES OFFSHORE CORPORATION
                             1400 BROADFIELD BLVD.
                                   SUITE 400
                           HOUSTON, TEXAS 77084-5133
 
                                August   , 1994
 
Dear Chiles Stockholder:
 
     You are cordially invited to attend a Special Meeting of Stockholders to be
held at 10:00 a.m., local time, on September   , 1994, at             , Houston,
Texas.
 
     At the Special Meeting, you will be asked to consider and vote upon a
proposal to authorize, approve and adopt an Agreement and Plan of Merger (the
"Merger Agreement") providing for the merger (the "Merger") of Chiles Offshore
Corporation ("Chiles") with and into a wholly owned subsidiary of Noble Drilling
Corporation ("Noble"). Under the terms of the Merger Agreement, (i) each
outstanding share of Chiles common stock, $.01 par value per share ("Chiles
Common Stock"), will be converted into the right to receive 0.75 of a share of
Noble common stock, $.10 par value per share, and (ii) each outstanding share of
Chiles $1.50 Convertible Preferred Stock, $1.00 par value per share ("Chiles
Preferred Stock"), will be converted into the right to receive one share of
$1.50 Convertible Preferred Stock, $1.00 par value per share, of Noble having
substantially the same rights, privileges, preferences and voting power as the
Chiles Preferred Stock.
 
     The Board of Directors of Chiles has retained the investment banking firm
of Salomon Brothers Inc to advise it with respect to the fairness of the
consideration to be received by the stockholders of Chiles in the Merger.
Salomon Brothers Inc has advised the Board that, in its opinion, the
consideration to be received by the Chiles common and preferred stockholders
pursuant to the Merger Agreement is fair to such holders from a financial point
of view. A copy of the opinion of Salomon Brothers Inc is included in the
enclosed Joint Proxy Statement/Prospectus as Appendix III thereto.
 
     THE BOARD OF DIRECTORS OF CHILES BELIEVES THAT THE MERGER IS FAIR TO AND IN
THE BEST INTERESTS OF CHILES AND ITS STOCKHOLDERS, AND UNANIMOUSLY RECOMMENDS
THAT THE HOLDERS OF CHILES COMMON STOCK VOTE FOR APPROVAL AND ADOPTION OF THE
MERGER AGREEMENT.
 
     A description of the basic terms and conditions of the Merger and financial
and other information concerning the business of Noble are included in the
enclosed Joint Proxy Statement/Prospectus. Please review the Joint Proxy
Statement/Prospectus carefully.
 
     Your vote is important. The affirmative vote of the holders of a majority
of the outstanding shares of Chiles Common Stock is required to approve the
Merger, so failure to vote will have the same effect as a vote against the
Merger. Accordingly, we urge you to complete, sign and date the enclosed proxy
card and return it promptly in the enclosed return envelope, whether or not you
plan to attend the meeting. If you do attend the meeting, you may withdraw your
proxy and vote in person if you wish to do so.
 
                                            Sincerely,
 
                                            C. RAY BEARDEN
                                            President
<PAGE>   6
                                  [NOBLE LOGO]

                           NOBLE DRILLING CORPORATION
                        10370 RICHMOND AVENUE, SUITE 400
                              HOUSTON, TEXAS 77042
 
                   NOTICE OF SPECIAL MEETING OF STOCKHOLDERS
 
                        TO BE HELD ON SEPTEMBER   , 1994
 
To the Stockholders of
  Noble Drilling Corporation:
 
     A special meeting of stockholders of Noble Drilling Corporation, a Delaware
corporation ("Noble"), will be held on                , September   , 1994, at
10:00 a.m., local time, at                               ,
          , Houston, Texas, for the following purposes:
 
          1. To consider and vote upon, as a single proposal, (a) the approval
     of the Agreement and Plan of Merger (the "Merger Agreement") attached as
     Appendix I to the accompanying Joint Proxy Statement/Prospectus, pursuant
     to which, among other things, (i) Chiles Offshore Corporation ("Chiles")
     would merge with and into a newly formed, wholly owned subsidiary of Noble
     (the "Merger") and (ii) each issued and outstanding share of Common Stock
     of Chiles would be converted in the Merger into the right to receive 0.75
     of a share of Common Stock of Noble and each issued and outstanding share
     of $1.50 Convertible Preferred Stock of Chiles would be converted in the
     Merger into the right to receive one share of a new series of $1.50
     Convertible Preferred Stock of Noble, subject to and in accordance with the
     terms and conditions of the Merger Agreement, and (b) the approval of the
     issuance of shares of Common Stock of Noble and the new series of $1.50
     Convertible Preferred Stock of Noble pursuant to the Merger Agreement;
 
          2. To consider and vote upon a proposal to amend Noble's Restated
     Certificate of Incorporation to increase the number of authorized shares of
     Common Stock of Noble from 75,000,000 to 200,000,000;
 
          3. To consider and vote upon a proposal to amend the Noble Drilling
     Corporation 1991 Stock Option and Restricted Stock Plan to (a) increase
     from 1,900,000 to 5,200,000 the aggregate number of shares of Common Stock
     of Noble available for issuance thereunder, (b) limit to 1,500,000 the
     total number of shares of Common Stock of Noble that may be made subject to
     grants of options or stock appreciation rights or awards of restricted
     stock under the Plan to any one person during any five-year period, and (c)
     provide for administration of the Plan by directors who are "outside"
     directors within the meaning of federal tax laws; and
 
          4. To transact such other business as may properly come before the
     meeting or any adjournment thereof.
 
     Regardless of whether the stockholders of Noble approve the Merger, the
Merger cannot be consummated unless the stockholders also adopt the proposal to
amend Noble's Restated Certificate of Incorporation.
 
     The Board of Directors has fixed the close of business on             ,
1994 as the record date for the determination of stockholders entitled to notice
of and to vote at the meeting or any adjournment thereof. Only holders of record
of shares of Common Stock of Noble at the close of business on the record date
are entitled to notice of and to vote at the meeting. A complete list of such
stockholders will be available for examination at the offices of Noble in
Houston, Texas during normal business hours by any Noble stockholder, for any
purpose germane to the special meeting, for a period of 10 days prior to the
meeting. Stockholders of Noble are not entitled to any appraisal or dissenter's
rights under the Delaware General Corporation Law in respect of the Merger.
 
     STOCKHOLDERS ARE URGED, WHETHER OR NOT THEY PLAN TO ATTEND THE MEETING, TO
SIGN, DATE AND MAIL THE ENCLOSED PROXY OR VOTING INSTRUCTION CARD IN THE
POSTAGE-PAID ENVELOPE PROVIDED. If a stockholder who has returned a proxy
attends the meeting in person, such stockholder may revoke the proxy and vote in
person on all matters submitted at the meeting.
 
                                        By Order of the Board of Directors
 
                                        JULIE J. ROBERTSON
                                        Secretary
Houston, Texas
August   , 1994
<PAGE>   7
 
                          CHILES OFFSHORE CORPORATION
                             1400 BROADFIELD BLVD.
                                   SUITE 400
                           HOUSTON, TEXAS 77084-5133
 
                   NOTICE OF SPECIAL MEETING OF STOCKHOLDERS
 
To the Stockholders of
  Chiles Offshore Corporation:
 
     Notice is hereby given that a special meeting of the stockholders of Chiles
Offshore Corporation (the "Special Meeting") will be held at
            , Houston, Texas, at 10:00 a.m., local time, on September   , 1994,
for the following purposes:
 
          1. To consider and vote upon a proposal to authorize, approve and
     adopt an Agreement and Plan of Merger, dated as of June 13, 1994 (the
     "Merger Agreement"), relating to the merger of Chiles Offshore Corporation
     ("Chiles") with and into a wholly owned subsidiary of Noble Drilling
     Corporation ("Noble") pursuant to which (i) each outstanding share of
     Chiles common stock, $.01 par value per share ("Chiles Common Stock"), will
     be converted into the right to receive 0.75 of a share of Noble common
     stock, $.10 par value per share, and (ii) each outstanding share of $1.50
     Convertible Preferred Stock, $1.00 par value per share, of Chiles will be
     converted into the right to receive one share of a new series of $1.50
     Convertible Preferred Stock, $1.00 par value per share, of Noble having
     substantially the same rights, privileges, preferences and voting power as
     the Chiles $1.50 Convertible Preferred Stock, all as more fully set forth
     in the accompanying Joint Proxy Statement/Prospectus and in the Merger
     Agreement, a copy of which is included as Appendix I thereto; and
 
          2. To transact such other business as may properly come before the
     Special Meeting.
 
     Only holders of record of Chiles Common Stock at the close of business on
            , 1994 are entitled to notice of and to vote at the Special Meeting.
A complete list of such stockholders will be available for examination at the
offices of Chiles in Houston, Texas during normal business hours by any Chiles
stockholder for any purpose germane to the Special Meeting for a period of 10
days prior to the meeting. Stockholders of Chiles are not entitled to any
appraisal or dissenter's rights under the Delaware General Corporation Law in
respect of the proposed merger.
 
     Your vote is important. The affirmative vote of the holders of a majority
of the outstanding shares of Chiles Common Stock is required for approval of the
Merger Agreement. Even if you plan to attend the meeting in person, we request
that you sign and return the enclosed proxy card and thus ensure that your
shares will be represented at the meeting if you are unable to attend. If you do
attend the meeting and wish to vote in person, you may withdraw your proxy and
vote in person.
 
                                            By order of the Board of Directors,
 
                                            ROBERT F. FULTON
                                            Secretary
 
Houston, Texas
August   , 1994
<PAGE>   8
 
***************************************************************************
*                                                                         *
*  INFORMATION CONTAINED HEREIN IS SUBJECT TO COMPLETION OR AMENDMENT. A  *
*  REGISTRATION STATEMENT RELATING TO THESE SECURITIES HAS BEEN FILED     *
*  WITH THE SECURITIES AND EXCHANGE COMMISSION. THESE SECURITIES MAY NOT  *
*  BE SOLD NOR MAY OFFERS TO BUY BE ACCEPTED PRIOR TO THE TIME THE        *
*  REGISTRATION STATEMENT BECOMES EFFECTIVE. THIS PROSPECTUS SHALL NOT    *
*  CONSTITUTE AN OFFER TO SELL OR THE SOLICITATION OF AN OFFER TO BUY     *
*  NOR SHALL THERE BE ANY SALE OF THESE SECURITIES IN ANY STATE IN WHICH  *
*  SUCH OFFER, SOLICITATION OR SALE WOULD BE UNLAWFUL PRIOR TO            *
*  REGISTRATION OR QUALIFICATION UNDER THE SECURITIES LAWS OF ANY SUCH    *
*  STATE.                                                                 *
*                                                                         *
***************************************************************************

 
                      SUBJECT TO COMPLETION, JULY 8, 1994
 
                           NOBLE DRILLING CORPORATION
 
                          CHILES OFFSHORE CORPORATION
 
                        JOINT PROXY STATEMENT/PROSPECTUS
                             ---------------------
     This Joint Proxy Statement/Prospectus relates to the proposed merger (the
"Merger") of Chiles Offshore Corporation ("Chiles"), a Delaware corporation,
with and into Noble Offshore Corporation ("Noble Sub"), a Delaware corporation
and a wholly owned subsidiary of Noble Drilling Corporation ("Noble"), a
Delaware corporation, pursuant to an Agreement and Plan of Merger among Noble,
Noble Sub and Chiles dated June 13, 1994 (the "Merger Agreement"). As a result
of the Merger, (i) the separate corporate existence of Chiles will cease and all
of the properties, rights, privileges, powers and franchises of Chiles will vest
in Noble Sub, which will be the surviving corporation in the Merger, and all of
the debts, liabilities and duties of Chiles will attach to Noble Sub, (ii) each
share of Common Stock of Chiles, par value $.01 per share ("Chiles Common
Stock"), outstanding immediately prior to the effective time of the Merger will
be converted into the right to receive 0.75 of a share of Common Stock of Noble,
par value $.10 per share ("Noble Common Stock"), and (iii) each share of $1.50
Convertible Preferred Stock of Chiles, par value $1.00 per share ("Chiles
Preferred Stock"), outstanding immediately prior to the effective time of the
Merger will be converted into the right to receive one share of a new series of
$1.50 Convertible Preferred Stock of Noble, par value $1.00 per share ("$1.50
Noble Preferred Stock"), having substantially the same rights, privileges,
preferences and voting power as the Chiles Preferred Stock.
 
     This Joint Proxy Statement/Prospectus is being furnished to holders of
Noble Common Stock and holders of Chiles Common Stock in connection with the
solicitation of proxies by the respective Boards of Directors of Noble and
Chiles for use at the special meetings of the stockholders of each company to be
held on September   , 1994. This Joint Proxy Statement/Prospectus and the
accompanying forms of proxy are first being mailed to stockholders of Noble and
Chiles on or about August   , 1994.
 
     At the Noble special meeting, holders of Noble Common Stock will be asked
to vote on (i) a proposal to approve the Merger Agreement and the issuance of
shares of Noble Common Stock and $1.50 Noble Preferred Stock pursuant thereto
(the "Merger Proposal"), (ii) a proposal to amend the Restated Certificate of
Incorporation of Noble to increase the number of authorized shares of Noble
Common Stock from 75,000,000 to 200,000,000 (the "Noble Charter Amendment") and
(iii) a proposal to amend the Noble Drilling Corporation 1991 Stock Option and
Restricted Stock Plan to (A) increase from 1,900,000 to 5,200,000 the aggregate
number of shares of Noble Common Stock available for issuance thereunder, (B)
limit to 1,500,000 the total number of shares of Common Stock of Noble that may
be made subject to grants of options or stock appreciation rights or awards of
restricted stock under the Plan to any one person during any five-year period,
and (C) provide for administration of the Plan by directors who are "outside"
directors within the meaning of federal tax laws (the "Noble Plan Amendment").
At the Chiles special meeting, the holders of Chiles Common Stock will be asked
to authorize, approve and adopt the Merger Agreement.
 
     This Joint Proxy Statement/Prospectus also constitutes a prospectus of
Noble with respect to (i) up to 28,844,280 shares of Noble Common Stock to be
issued pursuant to the Merger in exchange for Chiles Common Stock, (ii) up to
4,025,000 shares of $1.50 Noble Preferred Stock to be issued pursuant to the
Merger in exchange for Chiles Preferred Stock and an indeterminable number of
shares of Noble Common Stock issuable from time to time upon the conversion of
such $1.50 Noble Preferred Stock and (iii) up to 480,000 shares of Noble Common
Stock to be issued pursuant to the Merger Agreement in exchange for and upon the
cancellation of options to purchase Chiles Common Stock ("Chiles Options"), in
the event that each holder of Chiles Options approves such cancellation and
exchange. It is a condition to consummation of the Merger that the shares of
Noble Common Stock and $1.50 Noble Preferred Stock to be issued pursuant to the
Merger be approved for listing in the NASDAQ National Market System.
 
     On August   , 1994, the last reported sale prices of Noble Common Stock and
Chiles Common Stock, as reported in the NASDAQ National Market System and on the
American Stock Exchange, respectively, were $
and $     per share, respectively. Based on such prices, the consideration to be
received by holders of Chiles Common Stock pursuant to the Merger would be
$     per share of Chiles Common Stock.
 
     FOR A DISCUSSION OF CERTAIN CONSIDERATIONS REGARDING THE BUSINESS AND
OPERATIONS OF NOBLE AND CHILES THAT SHOULD BE EVALUATED BEFORE VOTING ON THE
PROPOSALS HEREIN AT THE NOBLE SPECIAL MEETING OR THE CHILES SPECIAL MEETING, SEE
"INVESTMENT CONSIDERATIONS."
                             ---------------------
 
THE SECURITIES TO WHICH THIS JOINT PROXY STATEMENT/PROSPECTUS RELATES HAVE
 NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND EXCHANGE
   COMMISSION OR ANY STATE SECURITIES COMMISSION NOR HAS THE SECURITIES AND
     EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION PASSED UPON
      THE ACCURACY OR ADEQUACY OF THIS JOINT PROXY STATEMENT/PROSPECTUS.
       ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.
 
     The date of this Joint Proxy Statement/Prospectus is August   , 1994.
<PAGE>   9
 
     NO PERSONS HAVE BEEN AUTHORIZED TO GIVE ANY INFORMATION OR TO MAKE ANY
REPRESENTATION OTHER THAN THOSE CONTAINED IN THIS JOINT PROXY
STATEMENT/PROSPECTUS IN CONNECTION WITH THE SOLICITATION OF PROXIES OR THE
OFFERING OF SECURITIES MADE HEREBY AND, IF GIVEN OR MADE, SUCH INFORMATION OR
REPRESENTATION SHOULD NOT BE RELIED UPON AS HAVING BEEN AUTHORIZED BY NOBLE OR
CHILES. THIS JOINT PROXY STATEMENT/PROSPECTUS DOES NOT CONSTITUTE AN OFFER TO
SELL, OR A SOLICITATION OF AN OFFER TO PURCHASE, ANY SECURITIES, OR THE
SOLICITATION OF A PROXY, IN ANY JURISDICTION IN WHICH, OR TO ANY PERSON TO WHOM,
IT IS UNLAWFUL TO MAKE SUCH OFFER OR SOLICITATION OF AN OFFER OR PROXY
SOLICITATION. NEITHER THE DELIVERY OF THIS JOINT PROXY STATEMENT/PROSPECTUS NOR
ANY DISTRIBUTION OF THE SECURITIES OFFERED HEREBY SHALL, UNDER ANY
CIRCUMSTANCES, CREATE ANY IMPLICATION THAT THERE HAS BEEN NO CHANGE IN THE
AFFAIRS OF NOBLE OR CHILES SINCE THE DATE HEREOF OR THAT THE INFORMATION SET
FORTH OR INCORPORATED BY REFERENCE HEREIN IS CORRECT AS OF ANY TIME SUBSEQUENT
TO ITS DATE.
 
                             AVAILABLE INFORMATION
 
     Noble and Chiles are subject to the informational requirements of the
Securities Exchange Act of 1934, as amended (the "Exchange Act"), and, in
accordance therewith, file reports, proxy statements and other information with
the Securities and Exchange Commission (the "Commission"). Such reports and
other information may be inspected and copied or obtained by mail upon the
payment of the Commission's prescribed rates at the public reference facilities
maintained by the Commission at Room 1024, Judiciary Plaza, 450 Fifth Street,
N.W., Washington D.C. 20549, and at the following Regional Offices of the
Commission: Northwest Atrium Center, 500 West Madison Street, Suite 1400,
Chicago, Illinois 60661; and Seven World Trade Center, New York, New York 10048.
Copies of such material can also be obtained at prescribed rates from the Public
Reference Section of the Commission at 450 Fifth Street, N.W., Washington, D.C.
20549. In addition, reports, proxy statements and other information filed by
Noble can be inspected at the offices of the National Association of Securities
Dealers, Inc., 1735 K Street, Washington, D.C. 20006, and reports, proxy
statements and other information filed by Chiles can be inspected at the offices
of the American Stock Exchange, 86 Trinity Place, New York, New York 10006-1881.
 
     Noble has filed with the Commission a registration statement on Form S-4
(together with all amendments, supplements and exhibits thereto, the
"Registration Statement") under the Securities Act of 1933, as amended (the
"Securities Act"), with respect to the shares of Noble Common Stock and $1.50
Noble Preferred Stock to be issued pursuant to the Merger Agreement, as well as
the Noble Common Stock subject to issuance upon conversion of the $1.50 Noble
Preferred Stock. Except as provided in the Merger Agreement, the information
contained herein with respect to Noble and its subsidiaries, including Noble
Sub, has been provided by Noble and the information with respect to Chiles and
its subsidiaries has been provided by Chiles. This Joint Proxy
Statement/Prospectus does not contain all of the information set forth in the
Registration Statement, certain parts of which are omitted in accordance with
the rules and regulations of the Commission. The Registration Statement and any
amendments thereto, including exhibits filed as a part thereof, are available
for inspection and copying as set forth above. Statements contained in this
Joint Proxy Statement/Prospectus or in any document incorporated in this Joint
Proxy Statement/Prospectus by reference as to the contents of any contract or
other document referred to herein or therein are not necessarily complete, and
in each instance reference is made to the copy of such contract or other
document filed as an exhibit to the Registration Statement or such other
document, each such statement being qualified in all respects by such reference.
 
                INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE
 
     The following documents, which have been filed with the Commission pursuant
to the Exchange Act, are incorporated herein by reference:
 
          1. Noble's Annual Report on Form 10-K for its fiscal year ended
     December 31, 1993, as amended by Amendment No. 1 to such Annual Report on
     Form 10-K/A dated June 28, 1994.
 
          2. Noble's Quarterly Report on Form 10-Q for the period ended March
     31, 1994.
 
                                        i
<PAGE>   10
 
          3. Noble's Current Report on Form 8-K dated April 22, 1994, as amended
     by Amendment No. 1 to such Current Report on Form 8-K/A dated June 30,
     1994.
 
          4. Noble's Current Report on Form 8-K dated June 13, 1994.
 
          5. The description of the Noble Common Stock contained in the
     Registration Statement on Form 10 of Noble heretofore filed with the
     Commission, including any amendments or reports filed for the purpose of
     updating such description.
 
          6. Chiles' Annual Report on Form 10-K for its fiscal year ended
     December 31, 1993.
 
          7. Chiles' Quarterly Report on Form 10-Q for the period ended March
     31, 1994.
 
          8. Chiles' Current Report on Form 8-K dated June 13, 1994.
 
     All documents and reports filed by Noble or Chiles pursuant to Section
13(a), 13(c), 14 or 15(d) of the Exchange Act after the date of this Joint Proxy
Statement/Prospectus and prior to the date of the special meetings of the
stockholders of each company shall be deemed to be incorporated by reference
herein and to be a part hereof from the respective dates of filing of such
documents or reports. All information appearing in this Joint Proxy
Statement/Prospectus or in any document incorporated herein by reference is not
necessarily complete and is qualified in its entirety by the information and
financial statements (including notes thereto) appearing in the documents
incorporated herein by reference and should be read together with such
information and documents. Any statement contained in a document incorporated or
deemed to be incorporated by reference herein shall be deemed to be modified or
superseded for purposes of this Joint Proxy Statement/Prospectus to the extent
that a statement contained herein (or in any subsequently filed document which
also is or is deemed to be incorporated by reference herein) modifies or
supersedes such statement. Any such statement so modified or superseded shall
not be deemed to constitute a part of this Joint Proxy Statement/Prospectus
except as so modified or superseded.
 
     THIS JOINT PROXY STATEMENT/PROSPECTUS INCORPORATES CERTAIN DOCUMENTS BY
REFERENCE WHICH ARE NOT PRESENTED HEREIN OR DELIVERED HEREWITH. NOBLE AND CHILES
EACH UNDERTAKE TO PROVIDE COPIES OF SUCH DOCUMENTS (OTHER THAN EXHIBITS TO SUCH
DOCUMENTS UNLESS SUCH EXHIBITS ARE SPECIFICALLY INCORPORATED BY REFERENCE),
WITHOUT CHARGE, TO ANY PERSON, INCLUDING ANY BENEFICIAL OWNER, TO WHOM THIS
JOINT PROXY STATEMENT/PROSPECTUS IS DELIVERED UPON WRITTEN OR ORAL REQUEST TO,
IN THE CASE OF DOCUMENTS RELATING TO NOBLE, JULIE J. ROBERTSON, CORPORATE
SECRETARY, NOBLE DRILLING CORPORATION, 10370 RICHMOND AVENUE, SUITE 400,
HOUSTON, TEXAS 77042 (TELEPHONE NUMBER 713/974-3131), AND IN THE CASE OF
DOCUMENTS RELATING TO CHILES, ROBERT F. FULTON, CORPORATE SECRETARY, CHILES
OFFSHORE CORPORATION, 1400 BROADFIELD BOULEVARD, SUITE 400, HOUSTON, TEXAS
77084-5133 (TELEPHONE NUMBER 713/647-0100). IN ORDER TO ENSURE TIMELY DELIVERY
OF THESE DOCUMENTS PRIOR TO THE SPECIAL MEETINGS OF STOCKHOLDERS, ANY REQUEST
SHOULD BE MADE BY SEPTEMBER   , 1994.
 
                                       ii
<PAGE>   11
 
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
                                                                                       PAGE
                                                                                       -----
<S>                                                                                    <C>
SUMMARY..............................................................................      1
  The Companies......................................................................      1
  The Meetings.......................................................................      1
  The Merger and the Merger Agreement................................................      2
  Investment Considerations..........................................................      7
  Noble Charter Amendment............................................................      7
  Noble Plan Amendment...............................................................      8
  Summary Historical Financial Data..................................................      9
  Summary Pro Forma Combined Financial Data..........................................     11
  Comparative Per Share Data.........................................................     12
THE COMPANIES........................................................................     13
  Noble Drilling Corporation.........................................................     13
  Chiles Offshore Corporation........................................................     14
THE MEETINGS.........................................................................     14
  Matters to be Considered at the Meetings...........................................     14
  Recommendations of the Boards of Directors.........................................     14
  Voting at Meetings; Record Dates...................................................     14
  Security Ownership of Management and Certain Other Persons.........................     15
  Proxies............................................................................     16
  Solicitation of Proxies............................................................     17
THE MERGER...........................................................................     17
  Effects of the Merger..............................................................     17
  Background of the Merger...........................................................     18
  Reasons for the Merger.............................................................     21
  Opinions of Financial Advisors.....................................................     22
  Certain Federal Income Tax Consequences............................................     30
  Anticipated Accounting Treatment...................................................     32
  Regulatory Approvals...............................................................     32
  Limitations on Resales; Registration Rights........................................     32
  Listing in NASDAQ National Market System...........................................     33
  No Appraisal Rights................................................................     34
  Interests of Certain Persons in the Merger.........................................     34
CERTAIN PROVISIONS OF THE MERGER AGREEMENT...........................................     35
  General............................................................................     35
  Effective Time of the Merger; Closing..............................................     35
  Conversion of Shares; Procedure for Exchange of Certificates; Fractional Shares....     35
  Representations and Warranties.....................................................     37
  Conduct of Business Prior to Effective Time........................................     37
  Solicitation of Third Party Offers.................................................     37
  Chiles Options.....................................................................     38
  NASDAQ National Market System Listing..............................................     39
  Indemnification....................................................................     39
  Chiles Employee Benefits...........................................................     39
  Registration Rights Agreement......................................................     39
  Certain Conditions to Consummation of the Merger...................................     39
  Termination........................................................................     40
</TABLE>
 
                                       iii
<PAGE>   12
 
<TABLE>
<CAPTION>
                                                                                       PAGE
                                                                                       -----
<S>                                                                                    <C>
INVESTMENT CONSIDERATIONS............................................................     41
  Intense Competition; Industry Conditions...........................................     41
  Losses from Operations.............................................................     41
  Substantial International Operations...............................................     42
  Concentration of Operations in Certain Markets.....................................     42
  Absence of Dividends on Noble Common Stock.........................................     42
  Restrictions on Foreign Ownership..................................................     42
  Operational Risks and Insurance....................................................     42
  Governmental Regulation and Environmental Matters..................................     43
  Limitation on Use of Net Operating Loss Carryforwards..............................     43
PROPOSAL TO ADOPT NOBLE CHARTER AMENDMENT............................................     44
  Background and Reasons.............................................................     44
  Proposed Noble Charter Amendment...................................................     44
  Recommendation and Required Affirmative Vote.......................................     45
PROPOSAL TO APPROVE NOBLE PLAN AMENDMENT.............................................     45
  General............................................................................     45
  Reasons and Principal Effects of the Proposal......................................     45
  Description of Plan as Currently in Effect.........................................     46
  United States Federal Income Tax Consequences......................................     47
  Recommendation and Required Affirmative Vote.......................................     49
UNAUDITED PRO FORMA COMBINED FINANCIAL STATEMENTS....................................     50
DESCRIPTION OF NOBLE CAPITAL STOCK...................................................     57
  Noble Common Stock.................................................................     57
  $2.25 Noble Preferred Stock........................................................     57
  $1.50 Noble Preferred Stock........................................................     59
  Federal Income Tax Considerations Regarding $1.50 Noble Preferred Stock............     66
  Restrictions on Dividends..........................................................     69
  Foreign Ownership..................................................................     70
  Certain Corporate Governance Provisions............................................     71
COMPARISON OF STOCKHOLDER RIGHTS.....................................................     73
  General............................................................................     73
  Authorized Capital.................................................................     73
  Removal of Directors...............................................................     74
  Power of Stockholders to Call Special Meeting......................................     74
  Classified Board and Fair Price Provision..........................................     74
MANAGEMENT AND OTHER INFORMATION.....................................................     74
LEGAL MATTERS........................................................................     75
EXPERTS..............................................................................     75
STOCKHOLDER PROPOSALS................................................................     75
APPENDIX I -- Agreement and Plan of Merger dated June 13, 1994
APPENDIX II -- Opinion of Simmons & Company International
APPENDIX III -- Opinion of Salomon Brothers Inc.
</TABLE>
 
                                       iv
<PAGE>   13
 
                                    SUMMARY
 
     The following is a summary of certain information contained elsewhere in
this Joint Proxy Statement/Prospectus. Reference is made to, and this summary is
qualified in its entirety by, the more detailed information contained in or
incorporated by reference in this Joint Proxy Statement/Prospectus and the
Appendices hereto. Stockholders are urged to carefully read this Joint Proxy
Statement/Prospectus and the Appendices hereto in their entirety. As used in
this Joint Proxy Statement/Prospectus, unless otherwise required by the context,
the term "Noble" means Noble Drilling Corporation and its consolidated
subsidiaries and the term "Chiles" means Chiles Offshore Corporation and its
consolidated subsidiaries.
 
                                 THE COMPANIES
 
     Noble and Noble Sub. Noble is a leading provider of contract drilling
services for the oil and gas industry worldwide. Noble Sub is a wholly owned
subsidiary of Noble recently incorporated in Delaware for the sole purpose of
effecting the Merger pursuant to the Merger Agreement. The principal executive
offices of Noble are located at 10370 Richmond Avenue, Suite 400, Houston, Texas
77042, and Noble's telephone number at such offices is (713) 974-3131.
 
     Chiles. Chiles is engaged in providing offshore oil and gas drilling
services on a contract basis in the Gulf of Mexico and West Africa. The
principal executive offices of Chiles are located at 1400 Broadfield Boulevard,
Suite 400, Houston, Texas 77084-5133, and Chiles' telephone number at such
offices is (713) 647-0100.
 
     For additional information concerning Noble and Chiles, see "The
Companies."
 
                                  THE MEETINGS
 
DATE, TIME AND PLACE
 
     Noble. The Special Meeting of Stockholders of Noble (the "Noble Special
Meeting") will be held on                , September   , 1994, at
                 , Houston, Texas, commencing at 10:00 a.m., local time.
 
     Chiles. The Special Meeting of Stockholders of Chiles (the "Chiles Special
Meeting") will be held on           , September   , 1994, at                  ,
Houston, Texas, commencing at 10:00 a.m., local time.
 
PURPOSES OF THE MEETINGS
 
     Noble. The purpose of the Noble Special Meeting is to consider and vote
upon (i) the Merger Proposal, which includes the approval of the Merger
Agreement and the approval of the issuance of shares of Noble Common Stock and
$1.50 Noble Preferred Stock pursuant to the Merger Agreement, (ii) a proposal to
adopt the Noble Charter Amendment, (iii) a proposal to approve the Noble Plan
Amendment and (iv) such other matters as may properly be brought before the
Noble Special Meeting.
 
     Chiles. The purpose of the Chiles Special Meeting is to consider and vote
upon (i) a proposal to authorize, approve and adopt the Merger Agreement and
(ii) such other matters as may properly be brought before the Chiles Special
Meeting.
 
RECORD DATES; SHARES ENTITLED TO VOTE
 
     Noble. Only holders of record of shares of Noble Common Stock at the close
of business on             , 1994 are entitled to notice of and to vote at the
Noble Special Meeting. On such date, there were 48,524,467 shares of Noble
Common Stock outstanding, each of which will be entitled to one vote on each
matter to be acted upon at the Noble Special Meeting.
 
     Chiles. Only holders of record of shares of Chiles Common Stock at the
close of business on           , 1994 are entitled to notice of and to vote at
the Chiles Special Meeting. On such date, there were 38,131,780 shares of Chiles
Common Stock outstanding, each of which will be entitled to one vote on each
matter to be acted upon at the Chiles Special Meeting.
 
                                        1
<PAGE>   14
 
QUORUM; VOTE REQUIRED
 
     Noble. The presence, in person or by proxy, at the Noble Special Meeting of
the holders of a majority of the shares of Noble Common Stock outstanding and
entitled to vote at the Noble Special Meeting is necessary to constitute a
quorum at the meeting. The affirmative vote of the holders of a majority of the
outstanding shares of Noble Common Stock present and entitled to vote thereon at
the Noble Special Meeting is required to approve the Merger Proposal and the
Noble Plan Amendment. Adoption of the Noble Charter Amendment requires the
affirmative vote of the holders of a majority of the shares of Noble Common
Stock outstanding and entitled to vote at the meeting.
 
     The respective obligations of Noble and Chiles to consummate the Merger are
subject to, among other conditions, the approval by the stockholders of Noble of
both the Merger Proposal and the Noble Charter Amendment. Thus, if the Noble
Charter Amendment is not adopted by the requisite vote of stockholders of Noble,
then the Merger cannot be consummated, notwithstanding that the Merger Proposal
may have been approved by the stockholders of Noble. The Noble Charter Amendment
will be effected if it is adopted by the stockholders of Noble irrespective of
whether such stockholders approve the Merger Proposal. Approval by the
stockholders of Noble of the Noble Plan Amendment is not a condition to
consummation of the Merger.
 
     Chiles. The presence, in person or by proxy, at the Chiles Special Meeting
of the holders of a majority of the shares of Chiles Common Stock outstanding
and entitled to vote at the Chiles Special Meeting is necessary to constitute a
quorum at the meeting. The affirmative vote of the holders of a majority of the
shares of Chiles Common Stock outstanding and entitled to vote at the meeting is
required to authorize, approve and adopt the Merger Agreement.
 
SECURITY OWNERSHIP OF MANAGEMENT AND CERTAIN OTHER PERSONS
 
     Noble. As of the record date for the Noble Special Meeting, the directors
and executive officers of Noble and their affiliates (excluding shares owned by
The Samuel Roberts Noble Foundation, Inc. (the "Foundation")) owned beneficially
approximately 1.5 percent of the outstanding shares of Noble Common Stock. Each
of the directors and executive officers has advised Noble that he intends to
vote or direct the vote of all shares of Noble Common Stock of which he has
beneficial ownership in favor of the approval and adoption of the Merger
Proposal, the Noble Charter Amendment and the Noble Plan Amendment. The
Foundation held, as of the record date, 5,459,537 shares of Noble Common Stock
(approximately 11.3 percent of the outstanding shares of Noble Common Stock).
Two directors of Noble serve on the nine-member board of trustees of the
Foundation. The voting of the shares held by the Foundation requires a majority
vote of its trustees at a meeting at which a quorum of trustees is present.
Accordingly, neither of the two directors of Noble, individually, nor both of
them acting together, represents sufficient voting power on the Foundation's
board of trustees to determine voting decisions with respect to shares held by
the Foundation.
 
     Chiles. As of the record date for the Chiles Special Meeting, the
directors, executive officers and two principal stockholders of Chiles, P.A.J.W.
Corporation ("P.A.J.W.") and OMI Investments, Inc. ("OMI"), held an aggregate of
14,916,342 shares of Chiles Common Stock (approximately 39.1 percent of the
outstanding shares of Chiles Common Stock). Such persons are not obligated to
vote their shares in favor of approval and adoption of the Merger Agreement, but
each of them or their representatives has advised Chiles that they presently
intend to vote their shares in favor of approval and adoption of the Merger
Agreement.
 
     For additional information concerning the special meetings, see "The
Meetings."
 
                      THE MERGER AND THE MERGER AGREEMENT
 
EFFECTS OF THE MERGER
 
     Subject to the terms and conditions of the Merger Agreement, at the
effective time of the Merger Chiles will merge with and into Noble Sub, with
Noble Sub being the surviving corporation, and all of the assets of Chiles will
vest in Noble Sub and all of the liabilities and obligations of Chiles will
attach to Noble Sub. By virtue of the Merger, each share of Chiles Common Stock
outstanding immediately prior to the effective time
 
                                        2
<PAGE>   15
 
of the Merger will be converted into the right to receive 0.75 of a share of
Noble Common Stock and each share of Chiles Preferred Stock outstanding
immediately prior to the effective time of the Merger will be converted into the
right to receive one share of $1.50 Noble Preferred Stock. Based on the
capitalization of Noble and Chiles as of the record date for the special
meetings, and assuming the cancellation of the Chiles Options in exchange for
480,000 shares of Noble Common Stock, pursuant to the Merger Agreement (i)
approximately 29,078,835 shares of Noble Common Stock will be issued, which
represents approximately 37.5 percent of the number of shares of Noble Common
Stock that would be outstanding immediately after the Merger, and (ii) 4,025,000
shares of $1.50 Noble Preferred Stock will be issued. See "The Merger -- Effects
of the Merger."
 
EFFECTIVE TIME OF THE MERGER
 
     It is anticipated that the Merger will become effective (the "Effective
Time") as promptly as practicable after the requisite stockholder approvals have
been obtained and all other conditions to the Merger have been satisfied or
waived. See "Certain Provisions of the Merger Agreement -- Effective Time of the
Merger; Closing."
 
PROCEDURE FOR EXCHANGE OF CERTIFICATES
 
     As soon as practicable after the Effective Time, each holder of a
certificate that prior thereto represented shares of Chiles Common Stock or
Chiles Preferred Stock will be entitled, upon surrender of such certificate to
Noble's transfer agent, Liberty Bank and Trust of Oklahoma City, N.A., to
receive in exchange therefor, as applicable, (i) a certificate(s) representing
the number of whole shares of Noble Common Stock into which such shares of
Chiles Common Stock were converted pursuant to the Merger or (ii) a
certificate(s) representing the number of shares of $1.50 Noble Preferred Stock
into which such shares of Chiles Preferred Stock were converted pursuant to the
Merger, in each case, in such denominations and registered in such names as the
holder may request. CHILES STOCKHOLDERS SHOULD NOT SEND IN ANY STOCK
CERTIFICATES AT THIS TIME. Following the Effective Time, Noble's transfer agent
will mail to each former holder of Chiles Common Stock or Chiles Preferred Stock
a letter describing how certificates representing Chiles Common Stock or Chiles
Preferred Stock should be presented for exchange.
 
     No fractional shares of Noble Common Stock will be issued in the Merger;
instead, cash will be paid in lieu thereof based on the market price of a share
of Noble Common Stock as of a specified date prior to the Effective Time. See
"Certain Provisions of the Merger Agreement -- Conversion of Shares; Procedure
for Exchange of Certificates; Fractional Shares."
 
RECOMMENDATIONS OF THE BOARDS OF DIRECTORS
 
     THE BOARDS OF DIRECTORS OF NOBLE AND CHILES BELIEVE THAT THE MERGER IS FAIR
TO AND IN THE BEST INTERESTS OF THEIR RESPECTIVE STOCKHOLDERS, AND EACH BOARD
HAS UNANIMOUSLY APPROVED THE MERGER AGREEMENT AND THE RELATED TRANSACTIONS. THE
BOARD OF DIRECTORS OF NOBLE UNANIMOUSLY RECOMMENDS THAT THE STOCKHOLDERS OF
NOBLE APPROVE AND ADOPT THE MERGER PROPOSAL, THE NOBLE CHARTER AMENDMENT AND THE
NOBLE PLAN AMENDMENT. THE BOARD OF DIRECTORS OF CHILES UNANIMOUSLY RECOMMENDS
THAT THE STOCKHOLDERS OF CHILES APPROVE AND ADOPT THE MERGER AGREEMENT. See "The
Meetings -- Recommendations of the Boards of Directors," and "The
Merger -- Background of the Merger" and "-- Reasons for the Merger."
 
     In considering the recommendation of the Board of Directors of Chiles in
favor of the Merger, stockholders of Chiles should be aware that certain
executive officers and directors of Chiles have direct or indirect interests in
recommending the Merger Agreement, apart from their interests as stockholders of
Chiles. See "The Merger -- Interests of Certain Persons in the Merger."
 
OPINIONS OF FINANCIAL ADVISORS
 
     Simmons & Company International ("Simmons") has delivered its written
opinion dated June 13, 1994 to the Board of Directors of Noble that, as of the
date of such opinion, the consideration to be paid by Noble
 
                                        3
<PAGE>   16
 
in the Merger was fair from a financial point of view to the holders of Noble
Common Stock and Noble $2.25 convertible exchangeable preferred stock.
 
     Salomon Brothers Inc ("Salomon") has delivered its written opinion dated
June 13, 1994 to the Board of Directors of Chiles that, as of the date of such
opinion, the consideration to be received by the holders of Chiles Common Stock
and Chiles Preferred Stock in the Merger was fair from a financial point of view
to such stockholders.
 
     For information regarding the opinions of Simmons and Salomon, including
the assumptions made, matters considered and limits of such opinions, see "The
Merger -- Opinions of Financial Advisors." Stockholders are urged to read in
their entirety the opinions of Simmons and Salomon, attached as Appendices II
and III, respectively, to this Joint Proxy Statement/Prospectus.
 
CERTAIN CONDITIONS TO THE CONSUMMATION OF THE MERGER
 
     The respective obligations of Noble and Chiles to consummate the Merger are
subject to the satisfaction of certain conditions, including the following: (i)
approval of the Merger Proposal and adoption of the Noble Charter Amendment by
the stockholders of Noble, and approval and adoption of the Merger Agreement by
the stockholders of Chiles; (ii) expiration or termination of the applicable
waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976,
as amended (the "HSR Act"); (iii) the absence of any order restraining or
preventing consummation of the Merger; (iv) all material required consents to
consummation of the Merger having been obtained; (v) the shares of Noble Common
Stock and $1.50 Noble Preferred Stock to be issued in connection with the Merger
having been approved for listing in the NASDAQ National Market System; (vi)
Noble and Chiles having been advised in writing by Arthur Andersen & Co. that
the Merger should qualify for treatment as a "pooling of interests" for
accounting purposes; and (vii) the fairness opinion of such party's financial
advisor having not been withdrawn.
 
     Noble and Chiles anticipate that substantially all of the above conditions
(other than obtaining the required approvals of the stockholders of Noble and
Chiles) will be satisfied prior to the Noble Special Meeting and the Chiles
Special Meeting. Either Noble or Chiles may extend the time for performance of
any of the obligations of the other party or may waive compliance with those
obligations at their discretion. See "Certain Provisions of the Merger Agreement
- -- Certain Conditions to Consummation of the Merger."
 
GOVERNMENTAL APPROVALS
 
     On July   , 1994, Noble and Chiles each filed a notification and report
under the HSR Act with the Federal Trade Commission and the Antitrust Division
of the Department of Justice. Expiration or early termination of the applicable
waiting period under the HSR Act is a condition to the obligation of Noble and
Chiles to consummate the Merger. See "The Merger -- Regulatory Approvals."
Neither Noble nor Chiles is aware of any other governmental or regulatory
approval required for consummation of the Merger, other than compliance with
applicable securities laws.
 
NO SOLICITATION
 
     The Merger Agreement provides that Chiles will not, directly or indirectly,
solicit or knowingly encourage the initiation of any inquiries or proposals
regarding (i) any merger, tender offer, sale of shares of capital stock or
similar business combination transaction involving Chiles that would have the
effect of causing the holders of Chiles Common Stock immediately prior to the
effectiveness of such proposed transaction to own in the aggregate less than 50
percent of the shares of the surviving or resulting entity entitled to vote
generally for the election of directors of the surviving or resulting entity, or
(ii) any sale of all or substantially all the assets of Chiles (collectively, a
"Chiles Acquisition Transaction"). Notwithstanding the foregoing, nothing in the
Merger Agreement prevents the members of the Board of Directors of Chiles, in
the exercise of their fiduciary duties and after consulting with independent
counsel, from considering, negotiating and approving an unsolicited bona fide
proposal that the Board determines in good faith, after consultation with its
financial advisors, may result in a transaction more favorable to the
stockholders of Chiles than the Merger. Further, the Board of Directors of
Chiles may elect not to convene the Chiles Special Meeting if it has received an
 
                                        4
<PAGE>   17
 
acquisition proposal it deems more favorable to the stockholders of Chiles. See
"Certain Provisions of the Merger Agreement -- Solicitation of Third Party
Offers."
 
TERMINATION OF THE MERGER AGREEMENT
 
     By Either Party. The Merger Agreement may be terminated prior to the
Effective Time (i) by mutual consent of Noble and Chiles, or (ii) by either
party if (A) the Merger has not been consummated on or before January 31, 1995,
(B) any court or governmental entity shall have prohibited consummation of the
Merger Agreement or the transactions contemplated in connection therewith or (C)
the required approvals of the stockholders of Noble or Chiles are not received
at the applicable stockholders' meeting.
 
     By Noble. Noble may terminate the Merger Agreement if (i) the fairness
opinion of Simmons is withdrawn, (ii) since the date of the Merger Agreement
there has been a material adverse change in the results of operations, financial
condition or business of Chiles, (iii) there has been a material breach of any
representation, warranty or covenant set forth in the Merger Agreement by Chiles
and such breach has not been cured within five business days following receipt
by Chiles of notice thereof or (iv) the Board of Directors of Chiles exercises
its right not to convene the Chiles Special Meeting on the grounds that the
Chiles Board has determined that another proposal for the acquisition of Chiles
is more favorable to the stockholders of Chiles than the Merger.
 
     By Chiles. Chiles may terminate the Merger Agreement if (i) the fairness
opinion of Salomon is withdrawn, (ii) since the date of the Merger Agreement
there has been a material adverse change in the results of operations, financial
condition or business of Noble or (iii) there has been a material breach of any
representation, warranty or covenant set forth in the Merger Agreement by Noble
and such breach has not been cured within five business days following receipt
by Noble of notice thereof.
 
     See "Certain Provisions of the Merger Agreement -- Termination."
 
TERMINATION FEES AND REIMBURSEMENT OF EXPENSES
 
     If either Noble or Chiles terminates the Merger Agreement for certain of
the reasons described above in "Termination of the Merger Agreement" and (i) the
Merger Agreement either has not been submitted to the stockholders of Chiles or
the stockholders of Chiles have declined to approve the Merger Agreement by the
requisite vote, (ii) after the date of the Merger Agreement but prior to the
time the Merger Agreement is terminated there shall have been a Chiles
Acquisition Transaction proposed in writing to Chiles and (iii) any Chiles
Acquisition Transaction (whether the same or different from the one referenced
in clause (ii)) is consummated within any time within one year after the date of
the Merger Agreement, then Chiles will be required to pay Noble the sum of
$6,000,000.
 
     In addition, if either Noble or Chiles terminates the Merger Agreement
because of the failure of the stockholders of the other to approve the Merger,
then the party whose stockholders have failed to approve the Merger will be
required to pay to the other party $1,000,000 as reimbursement for an agreed
upon estimate of the terminating party's out-of-pocket fees and expenses
incurred in connection with the Merger; provided, however, that if Chiles is
obligated to pay to Noble the $6,000,000 termination fee described in the
preceding paragraph, then Chiles may offset from the amount of such termination
fee any amount paid to Noble as a reimbursement for out-of-pocket fees and
expenses incurred in connection with the Merger. See "Certain Provisions of the
Merger Agreement -- Termination."
 
CERTAIN FEDERAL INCOME TAX CONSEQUENCES
 
     The Merger is intended to qualify as a reorganization under Section 368(a)
of the Internal Revenue Code of 1986, as amended, and should, therefore,
constitute a non-taxable transaction for holders of Chiles Common Stock and
Chiles Preferred Stock, except to the extent of cash received, if any, in lieu
of fractional shares of Noble Common Stock. For a discussion of these and other
federal income tax considerations in connection with the Merger, see "The
Merger -- Certain Federal Income Tax Consequences" and "Description of Noble
Capital Stock -- Federal Income Tax Considerations Regarding $1.50 Noble
Preferred Stock."
 
                                        5
<PAGE>   18
 
ANTICIPATED ACCOUNTING TREATMENT
 
     The Merger is expected to be accounted for as a "pooling of interests" for
accounting and financial reporting purposes. See "The Merger -- Anticipated
Accounting Treatment."
 
NO APPRAISAL RIGHTS
 
     Under Delaware law, neither Noble's nor Chiles' stockholders will be
entitled to any appraisal or dissenter's rights in connection with the Merger.
See "The Merger -- No Appraisal Rights."
 
INTERESTS OF CERTAIN PERSONS IN THE MERGER
 
     In considering the recommendation of the Board of Directors of Chiles with
respect to the Merger, Chiles stockholders should be aware that (i) two
executive officers of Chiles who are also directors of Chiles will receive
certain bonus payments upon consummation of the Merger pursuant to pre-existing
agreements with Chiles, (ii) two directors of Chiles are affiliates of a major
stockholder of Chiles that will enter into a registration rights agreement with
Noble, subject to consummation of the Merger, (iii) two of the executive
officers of Chiles who are also directors of Chiles have severance agreements
with Chiles that provide that should their employment be terminated by Noble
within one year of consummation of the Merger, under certain circumstances such
persons would be entitled to certain benefits, (iv) seven of the directors of
Chiles hold Chiles Options that will either be exchanged for shares of Noble
Common Stock or converted into options to purchase Noble Common Stock upon
consummation of the Merger and (v) two designees of Chiles, including a current
director of Chiles, will be elected to the Board of Directors of Noble effective
at the Effective Time. See "The Merger -- Interests of Certain Persons in the
Merger."
 
$1.50 NOBLE PREFERRED STOCK
 
     The $1.50 Noble Preferred Stock will have substantially the same rights,
preferences, privileges and voting power as the Chiles Preferred Stock. The
$1.50 Noble Preferred Stock will rank senior to the Noble Common Stock, and on a
parity with the outstanding $2.25 Convertible Exchangeable Preferred Stock of
Noble, par value $1.00 per share ("$2.25 Noble Preferred Stock"), with respect
to the payment of dividends and upon liquidation, dissolution or winding up of
Noble. See "Description of Noble Capital Stock -- $2.25 Noble Preferred Stock,"
"-- $1.50 Noble Preferred Stock" and " -- Federal Income Tax Considerations
Regarding the $1.50 Noble Preferred Stock." The ability of Noble to pay
dividends on the $1.50 Noble Preferred Stock will be subject to certain
contractual limitations pursuant to the indenture governing the Noble 9 1/4%
Senior Notes Due 2003 and Noble's bank credit agreement. The $1.50 Noble
Preferred Stock will rank on a parity with the $2.25 Noble Preferred Stock with
respect to the payment of dividends, which means that no dividends may be paid
on the $2.25 Noble Preferred Stock unless accrued dividends on the $1.50 Noble
Preferred Stock are also paid. See "Description of Noble Capital
Stock -- Restrictions on Dividends."
 
CHILES OPTIONS
 
     Pursuant to the Merger Agreement, all outstanding Chiles Options will be
either cancelled and exchanged for Noble Common Stock or converted into options
to purchase Noble Common Stock. Chiles has agreed to use its best efforts to
take all action necessary to provide for the exchange of all outstanding Chiles
Options for shares of Noble Common Stock. Such exchange will be consummated at
the Effective Time, provided that each holder of Chiles Options has consented
thereto. If such consents are obtained and based on the number of Chiles Options
currently outstanding, all such options shall be cancelled effective at the
Effective Time in exchange for an aggregate of 480,000 shares of Noble Common
Stock.
 
     If such consents have not been obtained by Chiles prior to the consummation
of the Merger, then the Chiles Options will not be exchanged for Noble Common
Stock and Noble will take all action necessary to assume, effective at the
Effective Time, all Chiles Options that remain as of such time unexercised in
whole or in part. Each Chiles Option will thereafter entitle the holder to
purchase that number of shares of Noble Common Stock equal to the product of the
number of shares of Chiles Common Stock subject to the Chiles
 
                                        6
<PAGE>   19
 
Option multiplied by 0.75. The exercise price per share of Noble Common Stock
under such assumed option will be equal to the exercise price per share under
the Chiles Option divided by 0.75. See "Certain Provisions of the Merger
Agreement -- Chiles Options."
 
LISTING OF SHARES; MARKET AND MARKET PRICES
 
     Noble Common Stock and the $2.25 Noble Preferred Stock are traded in the
NASDAQ National Market System under the symbols "NDCO" and "NDCOP,"
respectively, and application will be made to list the $1.50 Noble Preferred
Stock in the NASDAQ National Market System. Chiles Common Stock and Chiles
Preferred Stock are traded on the American Stock Exchange under the symbols
"CHC" and "CHCpr," respectively.
 
     The following table sets forth the closing sale prices per share of Noble
Common Stock and $2.25 Noble Preferred Stock as reported in the NASDAQ National
Market System, the closing sale prices per share of Chiles Common Stock and
Chiles Preferred Stock on the American Stock Exchange and the equivalent per
share price (as explained below) of Chiles Common Stock on June 10, 1994, the
business day preceding public announcement of the Merger, and on August   ,
1994, the last full trading day for which prices were available prior to the
date of this Joint Proxy Statement/Prospectus.
 
<TABLE>
<CAPTION>
                                                                                              EQUIVALENT
                                                                                              PER SHARE
                                                                                               PRICE OF
                                              NOBLE     $2.25 NOBLE    CHILES     CHILES        CHILES
                                              COMMON     PREFERRED     COMMON    PREFERRED      COMMON
MARKET PRICE PER SHARE AT:                    STOCK        STOCK       STOCK       STOCK        STOCK
- --------------------------                    ------    -----------    ------    ---------    ----------
<S>                                           <C>       <C>            <C>       <C>          <C>
June 10, 1994...............................  $7.00       $ 40.75      $5.00      $ 22.25       $ 5.25
August   , 1994.............................  $           $            $          $             $
</TABLE>
 
     The equivalent per share price of a share of Chiles Common Stock represents
the closing sale price of a share of Chiles Common Stock on such date multiplied
by the exchange ratio of 0.75 of a share of Noble Common Stock for each share of
Chiles Common Stock.
 
     Stockholders are advised to obtain current market quotations for Noble
Common Stock, Chiles Common Stock and Chiles Preferred Stock. No assurance can
be given as to the market price of Noble Common Stock, Chiles Common Stock or
Chiles Preferred Stock at, or in the case of Noble Common Stock and $1.50 Noble
Preferred Stock after, the Effective Time.
 
                           INVESTMENT CONSIDERATIONS
 
     For a discussion of certain considerations with respect to the business and
operations of Noble and Chiles that should be evaluated by an investor before
determining how to vote at the respective special meetings, see "Investment
Considerations."
 
                            NOBLE CHARTER AMENDMENT
 
     At the Noble Special Meeting, the holders of Noble Common Stock will also
be asked to adopt a proposal to amend the Restated Certificate of Incorporation
of Noble to increase the number of authorized shares of Noble Common Stock from
75,000,000 to 200,000,000. The Board of Directors of Noble has determined that
it is in the best interests of Noble and its stockholders to effect the Noble
Charter Amendment in order to permit Noble to consummate the Merger and to
provide Noble the flexibility to issue Noble Common Stock in future transactions
without further stockholder action. The obligations of Chiles and Noble to
consummate the Merger are conditioned upon receiving the approval and adoption
by the stockholders of Noble of the Merger Proposal and the Noble Charter
Amendment. The Noble Charter Amendment will be effected if it is adopted by the
stockholders of Noble irrespective of whether the Merger Proposal is approved.
See "Proposal to Adopt Noble Charter Amendment."
 
                                        7
<PAGE>   20
 
                              NOBLE PLAN AMENDMENT
 
     At the Noble Special Meeting, the holders of Noble Common Stock will also
be asked to approve an amendment to the Noble Drilling Corporation 1991 Stock
Option and Restricted Stock Plan in order to increase from 1,900,000 to
5,200,000 the number of shares of Noble Common Stock available for issuance
thereunder and to make certain amendments to conform with recent changes in
federal tax laws. The Board of Directors of Noble has determined that such
amendments are in the best interests of Noble and its stockholders because they
will permit the continuation of a compensation plan that assists Noble in
attracting and retaining key employees. If the Noble Plan Amendment is approved
by the Noble stockholders, the amendments will be effected whether or not the
Merger Proposal or the Noble Charter Amendment is approved or adopted by the
stockholders of Noble. See "Proposal to Approve Noble Plan Amendment." Approval
of the Noble Plan Amendment is not a condition to consummation of the Merger.
 
                                        8
<PAGE>   21
 
                       SUMMARY HISTORICAL FINANCIAL DATA
 
     The following tables set forth summary historical financial data of Noble
for each of the five fiscal years in the period ended December 31, 1993 and for
the three months ended March 31, 1994 and 1993, of Chiles for each of the same
periods and of Triton Engineering Services Company, a wholly owned subsidiary of
Noble ("Triton"), for the year ended December 31, 1993 and the three months
ended March 31, 1994. Noble acquired all of the issued and outstanding stock of
Triton in April 1994. For information regarding the acquisition by Noble of
Triton (the "Triton Acquisition"), see "The Companies -- Noble Drilling
Corporation -- Triton Acquisition." The data presented below have been derived
from and should be read in conjunction with the consolidated financial
statements of Noble, Triton and Chiles and the related notes thereto included in
the documents incorporated by reference in this Joint Proxy
Statement/Prospectus. Results for the interim periods are not necessarily
indicative of results for the full year.
 
                                     NOBLE
 
<TABLE>
<CAPTION>
                               THREE MONTHS ENDED
                                    MARCH 31,                      YEAR ENDED DECEMBER 31,
                               -------------------   ----------------------------------------------------
                                 1994     1993(A)    1993(A)      1992       1991       1990       1989
                               --------   --------   --------   --------   --------   --------   --------
                                          (IN THOUSANDS, EXCEPT PER SHARE AMOUNTS AND RATIOS)
<S>                            <C>        <C>        <C>        <C>        <C>        <C>        <C>
Statement of Operations Data:
  Operating revenues.......... $ 59,248   $ 52,172   $194,942   $139,713   $177,378   $131,353   $102,476
  Income (loss) from
     continuing
     operations(B)............    4,467      3,392     19,146     (8,085)   (13,360)    (8,752)   (10,082)
  Preferred stock dividends...    1,682      1,682      6,728      6,728        721
  Income (loss) from
     continuing operations
     applicable to common
     shares...................    2,785      1,710     12,418    (14,813)   (14,081)    (8,752)   (10,082)
  Income (loss) from
     continuing operations per
     common share(C)..........     0.06       0.05       0.32      (0.43)     (0.42)     (0.35)     (0.48)
  Weighted average common
     shares outstanding.......   48,355     34,712     38,366     34,014     33,656     26,796     22,509
  Ratio of earnings to fixed
     charges(D)...............     2.86       4.90       4.78
Balance Sheet Data (at end of
  period):
  Working capital............. $ 78,989   $ 26,591   $ 74,409   $ 23,734   $ 46,353   $ 42,741   $ 18,576
  Total assets(E).............  506,877    302,386    499,717    310,139    376,979    271,416    176,554
  Long-term debt(E)...........  127,138     38,839    127,144     41,255     71,166     59,471     20,047
  Shareholders' equity(E).....  331,480    213,920    328,953    211,728    230,307    169,461    118,656
</TABLE>
 
- ---------------
 
(A) Effective during the quarter ended March 31, 1993, Noble's international
    subsidiaries began reporting their financial results on a current rather
    than a month-lag basis. This change resulted in the inclusion of the
    December 1992 operating results of such international subsidiaries in the
    operating results of Noble for the first quarter of 1993. Revenues and
    income from continuing operations for this additional one-month period were
    $7,687,000 and $140,000; respectively, and are not considered material to
    the Noble's overall results of operations.
 
(B) Includes a charge for restructuring costs of $6,134,000 in 1991.
 
(C) Includes the effect of accretion on stock subject to put option prior to
    December 31, 1991, which is charged to retained earnings and not reflected
    in the amount of net loss applicable to common shares for each applicable
    period. The amount of the accretion was $92,000, $591,000 and $776,000 for
    the years ended December 31, 1991, 1990 and 1989, respectively.
 
(D) For the purposes of computing the ratio, "earnings" represents income (loss)
    from continuing operations before income taxes plus fixed charges exclusive
    of capitalized interest, and "fixed charges" consists of interest, whether
    expensed or capitalized, amortization of debt expense and an estimated
    portion of rentals representing interest costs. As a result of the losses
    incurred in 1992, 1991, 1990 and 1989, earnings did not cover fixed charges
    by $5,844,000, $12,339,000, $8,155,000 and $9,286,000, respectively.
 
(E) Includes the October 7, 1993 acquisition of nine offshore rigs and
    associated assets (the "Western Acquisition") from The Western Company of
    North America ("Western") for $150,000,000 in cash. Noble financed the
    Western Acquisition through public offerings of 12,041,000 shares of Noble
    Common Stock at $8.375 per share and $125,000,000 principal amount of
    Noble's 9 1/4% Senior Notes Due 2003.
 
                                        9
<PAGE>   22
 
                                     CHILES
 
<TABLE>
<CAPTION>
                                        THREE MONTHS ENDED
                                             MARCH 31,                      YEAR ENDED DECEMBER 31,
                                        -------------------   ----------------------------------------------------
                                          1994       1993       1993       1992       1991       1990       1989
                                        --------   --------   --------   --------   --------   --------   --------
                                                   (IN THOUSANDS, EXCEPT PER SHARE AMOUNTS AND RATIOS)
<S>                                     <C>        <C>        <C>        <C>        <C>        <C>        <C>
Statement of Operations Data(A):
  Operating revenues................... $ 19,673   $ 13,151   $ 69,589   $ 44,453   $ 52,773   $ 50,478   $ 27,228
  Income (loss) from continuing
    operations(B)......................    3,654     (3,725)     1,936    (31,893)   (25,814)    (2,762)   (10,531)
  Preferred stock dividends............    1,509                 1,208
  Income (loss) from continuing
    operations applicable to common
    shares.............................    2,145     (3,725)       728    (31,893)   (25,814)    (2,762)   (10,531)
  Income (loss) from continuing
    operations per common share........     0.06      (0.10)      0.02      (1.74)     (1.63)     (0.21)     (5.52)
  Weighted average common shares
    outstanding........................   38,097     38,053     38,076     18,330     15,864     13,410      1,907
  Ratio of earnings to fixed
    charges(C).........................    79.33                  1.86
Balance Sheet Data (at end of period):
  Working capital (deficit)(D)(E)...... $ 78,137   $ 16,611   $ 76,126   $ 19,259   $(49,592)  $ 11,446   $ 12,524
  Total assets.........................  199,358    144,235    196,836    146,390    184,008    203,015     62,065
  Long-term debt(D)(E).................              45,297                46,025      1,979     67,537     17,496
  Shareholders' equity(E)..............  189,967     85,990    187,817     89,906     94,060    119,874     38,217
</TABLE>
 
- ---------------
 
(A) Between 1989 and 1991, the Chiles' rig fleet changed substantially due to a
    series of acquisitions and dispositions. Such changes had a material effect
    on Chiles' capacity to generate revenue and the costs of its operations and
    should be considered carefully when examining the operating data included
    herein.
 
(B) Includes provisions which were made to reduce rig carrying values to their
    estimated recoverable values in 1992 and 1991 of $21,120,000 and 
    $5,000,000, respectively.
 
(C) For the purposes of computing the ratio, "earnings" represents income (loss)
    from continuing operations before income taxes plus fixed charges exclusive
    of capitalized interest, and "fixed charges" consists of interest, whether
    expensed or capitalized, amortization of debt expense and an estimated
    portion of rentals representing interest costs as a result of the losses 
    incurred in the first quarter 1993, and the years of 1992, 1991, 1990 and
    1989, earnings did not cover fixed charges by $3,483,000, $30,738,000,
    $25,472,000, $3,064,000 and $10,531,000, respectively.
 
(D) As of December 31, 1991, Chiles reclassified $50,500,000 of its outstanding
    indebtedness from long-term to current liabilities. This reclassification
    was made because as of such date Chiles anticipated not being able to
    remain in compliance, and subsequently was not able to remain in
    compliance, with all of the terms of its debt agreements.
 
(E) Chiles completed a public offering of Chiles Preferred Stock during October
    1993 which resulted in net proceeds of $96,500,000. Chiles used
    approximately $45,226,000 of such proceeds to repay all of its outstanding
    indebtedness, including prepayments of principal of $44,255,000. The
    remaining net proceeds were invested in cash and cash equivalents and
    marketable securities as of December 31, 1993 and March 31, 1994.
 
                                     TRITON
 
<TABLE>
<CAPTION>
                                                                                THREE
                                                                               MONTHS         YEAR
                                                                                ENDED        ENDED
                                                                              MARCH 31,    DECEMBER 31,
                                                                                1994          1993
                                                                              ---------    ------------
                                                                                   (IN THOUSANDS)
<S>                                                                            <C>           <C>
Statement of Operations Data:
  Operating revenues........................................................   $26,188       $123,834
  Income (loss) from continuing operations..................................    (2,491)(A)      1,506
Balance Sheet Data (at end of period):
  Working capital...........................................................   $14,153       $ 17,472
  Total assets..............................................................    61,035         72,171
  Long-term debt............................................................
  Shareholders' equity......................................................    12,918         15,157
</TABLE>
 
- ---------------
 
(A) Includes the write-off of $2,220,000 of notes receivable from a partnership
    that was not part of the Triton Acquisition.
 
                                       10
<PAGE>   23
 
                     SUMMARY PRO FORMA COMBINED FINANCIAL DATA
 
     The following summary unaudited pro forma combined financial data assume
(i) the consummation of the Merger and (ii) the consummation of both the Merger
and the Triton Acquisition. The Merger is accounted for as a "pooling of
interests" and the Triton Acquisition is accounted for as a "purchase"
transaction. The following pro forma statement of operations data do not purport
to be indicative of the results that would actually have been obtained if the
combinations had been in effect as of the dates indicated or that may be
obtained in the future. The following selected pro forma combined financial data
are derived from the unaudited pro forma combined financial statements and notes
thereto appearing elsewhere in this Joint Proxy Statement/Prospectus and should
be read in conjunction with such information and notes.
 
                                NOBLE AND CHILES
 
<TABLE>
<CAPTION>
                                                     THREE MONTHS ENDED
                                                         MARCH 31,              YEAR ENDED DECEMBER 31,
                                                    --------------------    --------------------------------
                                                      1994        1993        1993        1992        1991
                                                    --------    --------    --------    --------    --------
                                                      (IN THOUSANDS, EXCEPT PER SHARE AMOUNTS AND RATIOS)
<S>                                                 <C>         <C>         <C>         <C>         <C>
Statement of Operations Data:
  Operating revenues..............................  $ 78,921    $ 65,323    $264,531    $184,166    $230,151
  Income (loss) from continuing operations........     8,121        (333)     21,082     (39,978)    (39,174)
  Preferred stock dividends.......................     3,191       1,682       7,936       6,728         721
  Income (loss) from continuing operations
    applicable to common shares...................     4,930      (2,015)     13,146     (46,706)    (39,895)
  Income (loss) from continuing operations per
    common share..................................      0.06       (0.03)       0.20       (0.98)      (0.88)
  Pro forma weighted average common shares
    outstanding...................................    76,928      63,252      66,923      47,762      45,554
  Ratio of earnings to fixed charges(A)...........      4.11        1.39        3.73
Balance Sheet Data (at end of period):
  Working capital (deficit).......................  $157,126    $ 43,202    $150,535    $ 42,993    $ (3,239)
  Total assets....................................   706,235     446,621     696,553     456,529     560,987
  Long-term debt..................................   127,138      84,136     127,144      87,280      73,145
  Shareholders' equity............................   521,447     299,910     516,770     301,634     324,367
</TABLE>
 
- ---------------
 
(A) For the purposes of computing the ratio, "earnings" represents income (loss)
    from continuing operations before income taxes plus fixed charges exclusive
    of capitalized interest, and "fixed charges" consists of interest, whether
    expensed or capitalized, amortization of debt expense and an estimated
    portion of rentals representing interest costs. As a result of the losses
    incurred in 1992 and 1991, earnings did not cover fixed charges by
    $36,282,000 and $37,811,000, respectively.
 
                            NOBLE, CHILES AND TRITON
 
<TABLE>
<CAPTION>
                                                                               THREE
                                                                               MONTHS          YEAR
                                                                               ENDED           ENDED
                                                                             MARCH 31,      DECEMBER 31,
                                                                               1994             1993
                                                                             ---------      ------------
                                                                              (IN THOUSANDS, EXCEPT
                                                                                    PER SHARE
                                                                               AMOUNTS AND RATIOS)
<S>                                                                          <C>             <C>
Statement of Operations Data(A):
  Operating revenues......................................................   $105,056        $428,284
  Income from continuing operations.......................................      8,215          17,192
  Preferred stock dividends...............................................      3,191           7,936
  Income from continuing operations applicable to
    common shares.........................................................      5,024           9,256
  Income from continuing operations per common share......................       0.06            0.12
  Pro forma weighted average common shares outstanding....................     77,680          76,910
  Ratio of earnings to fixed charges......................................       4.32            2.41
Balance Sheet Data (at end of period):
  Working capital.........................................................   $163,194        $159,922
  Total assets............................................................    763,521         762,736
  Long-term debt..........................................................    127,138         127,144
  Shareholders' equity....................................................    526,616         521,939
</TABLE>
 
- ---------------
 
(A) Noble historical amounts were adjusted to include the effects of the Western
    Acquisition as if it had occurred on January 1, 1993.
 
                                       11
<PAGE>   24
 
                           COMPARATIVE PER SHARE DATA
 
     The following tables present comparative per share information (a) for each
of Noble and Chiles on a historical basis, (b) for Noble and Chiles on a pro
forma combined basis assuming the Merger had been effective during the periods
presented and (c) for Noble, Chiles and Triton on a pro forma combined basis
assuming the Merger and the Triton Acquisition had been effective during the
periods presented. The pro forma information has been prepared giving effect to
the Merger as a "pooling of interests" and to the Triton Acquisition as a
"purchase" transaction. Equivalent pro forma information for Chiles Common Stock
has been calculated based on the Merger exchange ratio of 0.75 of a share of
Noble Common Stock for each share of Chiles Common Stock. No cash dividends were
paid by Noble, Chiles or Triton during any of the periods presented.
 
<TABLE>
<CAPTION>
                                                    THREE MONTHS
                                                       ENDED
                                                     MARCH 31,           YEAR ENDED DECEMBER 31,
                                                  ----------------     ---------------------------
                                                  1994       1993      1993       1992       1991
                                                  -----     ------     -----     ------     ------
<S>                                               <C>       <C>        <C>       <C>        <C>
Noble -- Historical
  Income (loss) from continuing operations
     applicable to common shares................  $0.06     $ 0.05     $0.32     $(0.43)    $(0.42)
  Book value....................................   5.36       4.02      5.32       3.96       4.58
Chiles -- Historical
  Income (loss) from continuing operations
     applicable to common shares................  $0.06     $(0.10)    $0.02     $(1.74)    $(1.63)
  Book value....................................   2.35       2.26      2.29       2.36       5.93
Noble and Chiles -- Pro Forma
  Income (loss) from continuing operations
     applicable to common shares................  $0.06     $(0.03)    $0.20     $(0.98)    $(0.88)
  Book value....................................   4.53       3.56      4.47       3.60       5.44
Noble and Chiles -- Equivalent Pro Forma Per
  Chiles(A)
  Income (loss) from continuing operations
     applicable to common shares................  $0.05     $(0.02)    $0.15     $(0.73)    $(0.66)
  Book value....................................   3.40       2.68      3.36       2.70       4.09
Noble, Chiles and Triton -- Pro Forma
  Income from continuing operations applicable
     to common shares...........................  $0.06                $0.12
  Book value....................................   4.55                 4.49
</TABLE>
 
- ---------------
 
(A) Computed on an equivalent pro forma combined basis assuming Chiles was the
    issuing company.
 
                                       12
<PAGE>   25
 
                                 THE COMPANIES
 
NOBLE DRILLING CORPORATION
 
     Noble is a leading provider of diversified contract drilling services for
the oil and gas industry worldwide. Noble's activities include offshore and land
drilling services and engineering and production management services. Noble's
drilling fleet is broadly diversified allowing it to work in a variety of
operating conditions.
 
     Noble's business strategy has been to expand actively its international and
offshore capabilities through acquisitions and to position itself in
geologically promising areas. Noble attempts to balance its revenues between
international and domestic operations.
 
     Noble was organized as a Delaware corporation in 1939. Noble and its
predecessors have been engaged in the contract drilling of oil and gas wells for
others domestically since 1921 and internationally during various periods since
1939.
 
     Offshore Drilling Operations. Noble's offshore drilling operations are
conducted worldwide. Principal regions of operations currently include the Gulf
of Mexico, West Africa, Venezuela and, to a lesser extent, India. The offshore
fleet consists of 33 rigs, composed of 19 jackup drilling rigs, eight
submersible rigs, four posted barges and two platform rigs. The average age of
the offshore fleet is 11 years, with 23 of the 33 offshore rigs having been
built or rebuilt since 1980. The offshore fleet is currently diversified
geographically as follows: U.S. Gulf -- 18 rigs; Mexican Gulf -- two rigs;
Nigeria and West Africa -- six rigs; Venezuela -- four rigs; and India -- one
rig.
 
     Noble's offshore operations also include labor contracts for drilling and
workover activities covering 15 rigs operating in the U.K. North Sea. These rigs
are not owned or leased by Noble. Under these labor contracts, Noble provides
its customers with field personnel and manages the drilling operations.
 
     Land Operations. Noble's land drilling operations are conducted principally
in Western Canada, Texas and Louisiana. Eighteen of Noble's 48 land rigs are
being or can be actively bid by Noble. As of June 1, 1994, 12 of the 48 rigs
were operating under contract, six were available for bidding and 30 were not
being actively marketed. These 30 rigs are stacked and can be reactivated and
placed into operation in the near term should economically viable drilling
contracts for such rigs be obtained. The 18 active rigs have an average age of
14 years. The domestic land drilling operations of Noble are expected to
diminish in significance as Noble continues to emphasize offshore and
international operations.
 
     Engineering and Production Management Services. Noble provides, through its
wholly owned subsidiary, Noble Engineering Services Ltd., engineering services
relating primarily to the design of drilling equipment for offshore development
and production services. Noble Engineering works, on a contract basis, with
operators and prime construction contractors of drilling and production
platforms in the design of drilling equipment configurations aimed at optimizing
the operational efficiency of developmental drilling by maximizing platform
space utilization and load capability.
 
     Triton Acquisition. On April 22, 1994, Noble acquired all of the issued and
outstanding stock of Triton pursuant to a Stock Purchase Agreement among Noble,
Triton and the former stockholders of Triton (the "Triton Agreement"). Triton is
engaged in providing engineering, consulting and turnkey drilling services, and
manufacturing and rental of oil field equipment, for the oil and gas industry.
In consideration for the stock of Triton, Noble delivered to the former owners
of Triton (i) 751,864 shares of Noble Common Stock, (ii) $4,084,506 in cash and
(iii) promissory notes in the aggregate principal amount of $4,000,000, which
promissory notes mature on October 21, 1994. In addition, Noble has a contingent
obligation to pay to the former owners of Triton at the end of two years after
the closing date of the Triton Acquisition additional consideration, including
up to 254,551 shares of Noble Common Stock, subject to reduction depending on
the collection of certain contingent assets of Triton and the payment of certain
contingent liabilities of Triton, as well as an indeterminable number of
additional shares of Noble Common Stock in the event Triton achieves certain
operating results for the year ending December 31, 1994.
 
                                       13
<PAGE>   26
 
CHILES OFFSHORE CORPORATION
 
     Chiles is engaged in the drilling and workover of offshore oil and gas
wells on a contract basis for major and independent oil and gas companies.
Chiles' fleet consists of 13 jackup drilling rigs, 11 of which are located in
the U.S. Gulf of Mexico and two of which are located offshore Nigeria. Chiles'
two rigs operating offshore Nigeria are under contract until November 1994.
Eight Chiles rigs are currently operating under well-to-well contracts in the
U.S. Gulf of Mexico. One rig is stacked and actively being marketed in the U.S.
Gulf of Mexico. Chiles' two remaining rigs are not currently being marketed and
are stacked in the U.S. Gulf of Mexico.
 
     During May 1994, Chiles entered into commitments for capital expenditures
of approximately $6 million in connection with the fabrication and construction
of an extended reach cantilever for one of its three Marathon LeTourneau slot
rigs. Construction of the extended reach cantilever is currently underway.
 
                                  THE MEETINGS
 
MATTERS TO BE CONSIDERED AT THE MEETINGS
 
     Noble Special Meeting. At the Noble Special Meeting, holders of Noble
Common Stock will be asked to consider and vote upon:
 
          (1) The Merger Proposal, which includes, as a single proposal, (a) the
     approval of the Merger Agreement, pursuant to which, among other things,
     (i) Chiles would merge with and into Noble Sub and (ii) each issued and
     outstanding share of Chiles Common Stock would be converted in the Merger
     into the right to receive 0.75 of a share of Noble Common Stock and each
     issued and outstanding share of Chiles Preferred Stock would be converted
     in the Merger into the right to receive one share of $1.50 Noble Preferred
     Stock, subject to and in accordance with the terms and conditions of the
     Merger Agreement, and (b) the approval of the issuance of shares of Noble
     Common Stock and $1.50 Noble Preferred Stock pursuant to the Merger
     Agreement;
 
          (2) a proposal to adopt the Noble Charter Amendment;
 
          (3) a proposal to approve the Noble Plan Amendment; and
 
          (4) such other matters as may properly be brought before the Noble
     Special Meeting.
 
     Chiles Special Meeting. At the Chiles Special Meeting, holders of Chiles
Common Stock will be asked to consider and vote upon the authorization, approval
and adoption of the Merger Agreement and such other matters as may properly be
brought before the Chiles Special Meeting.
 
RECOMMENDATIONS OF THE BOARDS OF DIRECTORS
 
     Noble. The Board of Directors of Noble has unanimously approved (i) the
Merger, the Merger Agreement and the issuance of shares of Noble Common Stock
and $1.50 Noble Preferred Stock pursuant to the Merger Agreement, (ii) the Noble
Charter Amendment and (iii) the Noble Plan Amendment, and unanimously recommends
that the stockholders of Noble vote FOR approval and adoption of each such
matter.
 
     Chiles. The Board of Directors of Chiles has unanimously approved the
Merger and the Merger Agreement and unanimously recommends that the stockholders
of Chiles vote FOR authorization, approval and adoption of the Merger Agreement.
 
VOTING AT MEETINGS; RECORD DATES
 
     Noble. Noble has established             , 1994, as the record date for the
determination of stockholders entitled to notice of and to vote at the Noble
Special Meeting. Only holders of record of Noble Common Stock at the close of
business on such date are entitled to notice of and to vote at the Noble Special
 
                                       14
<PAGE>   27
 
Meeting. On the record date for the Noble Special Meeting, there were 48,524,467
shares of Noble Common Stock outstanding and entitled to be voted at the Noble
Special Meeting. A majority of such shares, present in person or represented by
proxy, is necessary to constitute a quorum at the Noble Special Meeting. Each
share of Noble Common Stock is entitled to one vote with respect to the approval
of the Merger Proposal, the adoption of the Noble Charter Amendment and the
approval of the Noble Plan Amendment. Holders of $2.25 Noble Preferred Stock are
not entitled as such to vote at the Noble Special Meeting.
 
     The affirmative vote of the holders of a majority of the outstanding shares
of Noble Common Stock present and entitled to vote thereon at the Noble Special
Meeting is required to approve the Merger Proposal. Approval of the Merger
Proposal will constitute approval of each aspect of the Merger Proposal.
Approval of the Merger Proposal by the holders of Noble Common Stock is required
by the rules of the National Association of Securities Dealers, Inc. for
companies, like Noble, with securities listed in the NASDAQ National Market
System and is a condition to the consummation of the Merger.
 
     Adoption of the Noble Charter Amendment requires the affirmative vote of
the holders of a majority of the shares of Noble Common Stock outstanding and
entitled to vote at the meeting. Approval of the Noble Plan Amendment requires
the affirmative vote of the holders of a majority of the outstanding shares of
Noble Common Stock present and entitled to vote thereon at the Noble Special
Meeting.
 
     The respective obligations of Noble and Chiles to consummate the Merger are
subject to, among other conditions, the approval and adoption by the
stockholders of Noble of both the Merger Proposal and the Noble Charter
Amendment. Thus, notwithstanding the approval of the Merger Proposal at the
Noble Special Meeting, if the Noble Charter Amendment is not adopted by the
requisite vote of the stockholders of Noble, the Merger will not be consummated.
If the Noble Charter Amendment is adopted by stockholders, it will be effected
regardless of whether the Merger Proposal is approved.
 
     Chiles. Chiles has established             , 1994, as the record date for
the determination of stockholders entitled to notice of and to vote at the
Chiles Special Meeting. Only holders of record of Chiles Common Stock at the
close of business on such date are entitled to notice of and to vote at the
Chiles Special Meeting. On the record date for the Chiles Special Meeting, there
were 38,131,780 shares of Chiles Common Stock outstanding and entitled to be
voted at the Chiles Special Meeting. A majority of such shares, present in
person or represented by proxy, is necessary to constitute a quorum at the
Chiles Special Meeting. Each share of Chiles Common Stock is entitled to one
vote with respect to the approval and adoption of the Merger Agreement. The
affirmative vote of the holders of a majority of the shares of Chiles Common
Stock outstanding and entitled to vote at the meeting is required to authorize,
approve and adopt the Merger Agreement. Holders of Chiles Preferred Stock are
not entitled as such to vote on the Merger at the Chiles Special Meeting.
 
SECURITY OWNERSHIP OF MANAGEMENT AND CERTAIN OTHER PERSONS
 
     Noble. As of the record date for the Noble Special Meeting, directors and
executive officers of Noble and their affiliates (excluding shares owned by the
Foundation) owned beneficially approximately 1.5 percent of the outstanding
shares of Noble Common Stock. Each of the directors and executive officers of
Noble has advised Noble that he intends to vote or direct the vote of all shares
of Noble Common Stock of which he has beneficial ownership in favor of the
approval and adoption of the Merger Proposal, the Noble Charter Amendment and
the Noble Plan Amendment. The Foundation held, as of the record date for the
Noble Special Meeting, 5,459,537 shares of Noble Common Stock (approximately
11.3 percent of the outstanding shares). Two directors of Noble serve on the
nine-member board of trustees of the Foundation. The voting of the shares held
by the Foundation requires a majority vote of its trustees at a meeting at which
a quorum of trustees is present. Accordingly, neither of the two directors of
Noble, individually, nor both of them, acting together, represent sufficient
voting power on the Foundation's board of trustees to determine voting decisions
with respect to shares held by the Foundation.
 
     Chiles. As of the record date for the Chiles Special Meeting, the
directors, executive officers and two principal stockholders of Chiles, P.A.J.W.
and OMI, held an aggregate of 14,916,342 shares of Chiles Common Stock
(approximately 39.1 percent of the outstanding shares). Such persons are not
obligated to
 
                                       15
<PAGE>   28
 
vote their shares in favor of approval and adoption of the Merger Agreement, but
each of them or their representatives has advised Chiles that they presently
intend to vote their shares in favor of approval and adoption of the Merger
Agreement.
 
PROXIES
 
     Noble. Shares of Noble Common Stock represented by a proxy in the form
enclosed, duly executed and returned to Noble prior to or at the Noble Special
Meeting, and not revoked, will be voted at the Noble Special Meeting in
accordance with the voting instructions contained therein. Shares of Noble
Common Stock represented by proxies for which no voting instructions are given
will be voted FOR approval and adoption of the Merger Proposal, the Noble
Charter Amendment and the Noble Plan Amendment.
 
     Holders of Noble Common Stock are requested to complete, sign, date and
return promptly the enclosed proxy card in the postage paid envelope provided
for this purpose in order to insure that their shares are voted at the Noble
Special Meeting. A proxy may be revoked at any time prior to the exercise of the
authority granted thereunder. Revocation may be accomplished by (i) the
execution and delivery of a later-dated proxy with respect to the same shares,
(ii) giving notice thereof in writing to the Secretary of Noble at any time
prior to the vote on the matters to be considered at the Noble Special Meeting
or (iii) attending the Noble Special Meeting and voting in person. Attendance at
the Noble Special Meeting by a stockholder who signed a proxy will not in itself
revoke the proxy.
 
     If a holder of Noble Common Stock does not return a signed proxy card (and
does not vote in person at the Noble Special Meeting), his or her shares will
not be voted at the Noble Special Meeting. Such failure to vote will have the
effect of a vote against the adoption of the Noble Charter Amendment, and thus
effectively a vote against the Merger. Abstentions and broker non-votes with
respect to the Noble Charter Amendment will also have the effect of a vote
against the adoption of the Noble Charter Amendment, and thus effectively a vote
against the Merger.
 
     If a voting instruction card is enclosed, it serves as a voting instruction
to the trustee of the Noble Drilling Corporation Thrift Plan, as amended (the
"Thrift Plan"), from the plan participant. The trustee under the Thrift Plan
will vote the shares of Noble Common Stock credited to Thrift Plan participants'
accounts in accordance with such participants' instructions. If no such voting
instructions are received from a participant, then, according to the terms of
the Thrift Plan, the trustee under the Thrift Plan will vote the shares in such
participant's account in its absolute discretion.
 
     The Board of Directors of Noble knows of no matters to be presented at the
Noble Special Meeting other than those described in this Joint Proxy
Statement/Prospectus. If other matters are properly brought before the Noble
Special Meeting, it is the intention of the persons named as proxies to vote
with respect to such matters in accordance with their judgment.
 
     Chiles. Shares of Chiles Common Stock represented by a proxy in the form
enclosed, duly executed and returned to Chiles prior to or at the Chiles Special
Meeting, and not revoked, will be voted at the Chiles Special Meeting in
accordance with the voting instructions contained therein. Shares of Chiles
Common Stock represented by proxies for which no voting instructions are given
will be voted FOR approval and adoption of the Merger Agreement.
 
     Holders of Chiles Common Stock are requested to complete, sign, date and
return promptly the enclosed proxy card in the postage paid envelope provided
for this purpose in order to insure that their shares are voted at the Chiles
Special Meeting. A proxy may be revoked at any time prior to the exercise of the
authority granted thereunder. Revocation may be accomplished by (i) the
execution and delivery of a later dated proxy with respect to the same shares,
(ii) giving notice thereof in writing to the Secretary of Chiles at any time
prior to the vote on the matters to be considered at the Chiles Special Meeting
or (iii) attending the Chiles Special Meeting and voting in person. Attendance
at the Chiles Special Meeting by a stockholder who signed a proxy will not in
itself revoke the proxy.
 
                                       16
<PAGE>   29
 
     If a holder of Chiles Common Stock does not return a signed proxy card (and
does not vote in person at the Chiles Special Meeting), his or her shares will
not be voted at the Chiles Special Meeting. Such failure to vote will have the
effect of a vote against the approval and adoption of the Merger Agreement.
Abstentions and broker non-votes with respect to shares of Chiles Common Stock
will also have the effect of a vote against the approval and adoption of the
Merger Agreement.
 
     The Board of Directors of Chiles knows of no matters to be presented at the
Chiles Special Meeting other than the matter described in this Joint Proxy
Statement/Prospectus. If other matters are properly brought before the Chiles
Special Meeting, it is the intention of the persons named as proxies to vote
with respect to such matters in accordance with their judgment.
 
SOLICITATION OF PROXIES
 
     Solicitation of proxies for use at the Noble Special Meeting and the Chiles
Special Meeting may be made in person or by mail, telephone, telecopy or
telegram. Noble and Chiles will each bear the cost of the solicitation of
proxies from their respective stockholders, except that Noble and Chiles will
share equally the expenses incurred in connection with printing and mailing this
Joint Proxy Statement/Prospectus. Noble has employed Beacon Hill Partners, Inc.
to solicit proxies on behalf of Noble for use at the Noble Special Meeting for a
fee of $6,500 plus certain out-of-pocket expenses. In addition, officers and
employees of Noble and Chiles, who will receive no compensation in excess of
their regular salaries for their services, may solicit proxies from the
stockholders of Noble and Chiles, respectively, in person or by mail, telephone,
telecopy or telegram. Noble and Chiles have requested banking institutions,
brokerage firms, custodians, trustees, nominees and fiduciaries to forward
solicitation materials to the beneficial owners of Noble Common Stock and Chiles
Common Stock held of record by such entities, and Noble and Chiles will, upon
the request of such record holders, reimburse reasonable forwarding expenses.
 
                                   THE MERGER
 
     The detailed terms and conditions to the consummation of the Merger are
contained in the Merger Agreement, a copy of which is attached as Appendix I and
incorporated herein by reference. The following discussion sets forth a
description of certain material terms and conditions of the Merger Agreement.
The description in this Joint Proxy Statement/Prospectus of the terms and
conditions to the consummation of the Merger is qualified by, and made subject
to, the more complete information set forth in the Merger Agreement.
 
EFFECTS OF THE MERGER
 
     Pursuant to the Merger Agreement, at the Effective Time, Chiles will merge
with and into Noble Sub and each share of capital stock of Chiles issued and
outstanding immediately prior to the Effective Time (other than shares of
capital stock of Chiles owned by Chiles as treasury stock which will be
cancelled without any conversion thereof) will be converted into the right to
receive shares of capital stock of Noble as follows:
 
          (i) Chiles Common Stock. Each share of Chiles Common Stock will be
     converted into the right to receive 0.75 of a share of Noble Common Stock.
 
          (ii) Chiles Preferred Stock. Each share of Chiles Preferred Stock will
     be converted into the right to receive one share of $1.50 Noble Preferred
     Stock having substantially the same rights, privileges, preferences and
     voting power as the Chiles Preferred Stock.
 
     As a result of the Merger, the separate corporate existence of Chiles will
cease and all of the properties, rights, privileges, powers and franchises of
Chiles will vest in Noble Sub, which will be the surviving corporation in the
Merger, and all of the debts, liabilities and duties of Chiles will attach to
Noble Sub.
 
     Assuming no change in the number of shares of Chiles Common Stock
outstanding at the Effective Time from the number outstanding on the record date
for the Chiles Special Meeting, the number of shares of Noble Common Stock
subject to issuance in the Merger in exchange for shares of Chiles Common Stock
is
 
                                       17
<PAGE>   30
 
approximately 28,598,835. Assuming no change in the number of shares of Chiles
Preferred Stock outstanding at the Effective Time from the number outstanding on
the record date for the Chiles Special Meeting, a total of 4,025,000 shares of
$1.50 Noble Preferred Stock are subject to issuance in the Merger in exchange
for shares of Chiles Preferred Stock.
 
     A total of 480,000 additional shares of Noble Common Stock are issuable
upon consummation of the Merger in exchange for and upon the cancellation of
Chiles Options outstanding at the record date for the Chiles Special Meeting, in
the event that each holder of Chiles Options approves such cancellation and
exchange. See "Certain Provisions of the Merger Agreement -- Chiles Options."
 
     Based on the capitalization of Noble and Chiles as of the record date for
the special meetings, and assuming the cancellation of the Chiles Options in
exchange for 480,000 shares of Noble Common Stock, immediately after the
Effective Time, the former holders of Chiles Common Stock and Chiles Options
will hold approximately 37.5 percent of the then outstanding Noble Common Stock.
Noble does not own any shares of Chiles Common Stock or Chiles Preferred Stock.
 
BACKGROUND OF THE MERGER
 
     The drilling industry has historically been highly competitive, due mainly
to a large number of participants and a substantial oversupply of drilling
equipment. As worldwide drilling activity has declined over the past decade, the
industry has experienced substantial financial losses. During this period,
drilling operations in the U.S. Gulf of Mexico have been particularly volatile
and have been characterized by the movement of drilling rigs into and away from
the Gulf in response to changes in demand.
 
     In response to these conditions, and in an effort to protect and enhance
stockholder value, Noble established certain objectives in 1985 to expand its
offshore and international operations. Since that time Noble has been active in
acquiring entities and assets in furtherance of those objectives, most recently
with the acquisition of Triton in April 1994. In October 1993, Noble acquired
nine offshore jackup drilling rigs and associated drilling assets from The
Western Company of North America, as well as two submersible offshore drilling
rigs from Portal Rig Corporation. In 1991, Noble acquired 12 offshore drilling
rigs (five jackup and seven submersible rigs) and certain related assets from
Transworld Drilling Company, a wholly owned subsidiary of Kerr-McGee
Corporation. In 1988, Noble purchased Peter Bawden Drilling Ltd. (now named
Noble Drilling (Canada) Ltd.) and its subsidiaries, which had established
operations in the U.K. North Sea, Africa, the Far East and Canada. Also in 1988,
Noble purchased six offshore and 20 land rigs and certain related assets from
General Electric Capital Corporation.
 
     As a continuation of such efforts, and while maintaining its focus on
enhancing stockholder value, Noble has from time to time explored several
possible acquisitions that management believed could help Noble meet its
objectives. Analyses prepared by Noble management demonstrated that, among
others, Chiles met Noble's criteria.
 
     During 1993, Chiles accomplished several significant operational and
financial goals that enabled it to reassess the company's long-term business
strategy. Higher day rates and utilization for the company's rigs together with
significant operating and administrative cost reductions undertaken beginning in
the second half of 1992 resulted in Chiles reporting an operating profit for the
first time in its history. Additionally, the offering of the Chiles Preferred
Stock in October 1993 permitted Chiles to prepay all of its outstanding bank
debt. Chiles ended 1993 with net working capital of $76.1 million and a fleet of
12 jackup rigs in the Gulf of Mexico and two jackup rigs offshore Nigeria.
Chiles sold one of its rigs in April 1994.
 
     Having made significant improvements in Chiles' cost structure and
eliminated its debt, the Board of Directors of Chiles undertook the process of
reevaluating Chiles' long-term strategic objectives in late 1993. As part of
this analysis, the Chiles Board came to the conclusion that future success in
the offshore drilling business would require industry consolidation, access to
multiple core offshore oil and gas regions internationally in addition to the
Gulf of Mexico and the capability to provide customers with a broader range of
drilling services and equipment. The Chiles Board believed that the long-term
prospects of Chiles' stockholders would
 
                                       18
<PAGE>   31
 
best be served if these strategic objectives could be achieved as soon as
possible. In addition, the Board concluded that its fleet was not large enough
to establish a presence in multiple markets without increasing its fixed costs
to unacceptable levels. The Board directed management to explore Chiles'
opportunities for expansion through selected rig acquisitions or a business
combination.
 
     Management of Chiles explored the prospects for selected rig acquisitions
early in 1994. Chiles focused on premium jackup rigs capable of operating in
markets outside the U.S. as well as in relatively deep water in the Gulf of
Mexico. Chiles found few premium jackup drilling rigs available in the market at
prices upon which it could reasonably expect to earn an acceptable return for
its stockholders. As a result, management advised the Board that its strategic
objectives could best be addressed through one or more business combinations.
 
     In January 1994, Chiles engaged Salomon to serve as its financial advisor
in connection with a review of Chiles' strategic alternatives. At the Board's
request, Salomon undertook a review of possible business combination candidates,
including offshore drilling contractors (including Noble) and other energy
service companies. Salomon presented the results of its initial analysis to the
Board at a meeting on February 8, 1994. At the conclusion of this meeting, the
Board directed management to focus its efforts on reviewing certain potential
business combination transactions that fit Chiles' strategic objectives as
discussed above.
 
     During February-April 1994, Chiles' management engaged in exploratory
discussions with several offshore drilling contractors. The Chiles Board met by
telephone with representatives of Salomon on March 7, 1994 to continue
discussions regarding the status of potential candidates for a combination
transaction. With the exception of Noble and one other company, as noted below,
these conversations were exploratory in nature and did not lead to any proposals
from Chiles or any other party.
 
     On February 17, 1994, representatives of Marine Drilling Company ("Marine")
contacted Mr. Winthrop A. Wyman, who was chairman of the Board of Chiles on such
date, regarding Marine's interest in a business combination with Chiles. Mr.
Wyman met with Marine's representatives and informed the other members of the
Chiles Board of Marine's interest in discussing a business combination with
Chiles. Marine is a publicly traded offshore drilling contractor with 11 jackup
drilling rigs all located in the Gulf of Mexico. Representatives of Marine and
Chiles had engaged in similar discussions on various occasions in the past. Such
discussions had been exploratory in nature. On March 4, 1994, Mr. Wyman,
together with Mr. C. Ray Bearden, President of Chiles, and Mr. Robert F. Fulton,
Senior Vice President and Chief Financial Officer of Chiles, met with
representatives of Marine to dicuss the terms of a possible combination. By
letters dated April 9, 1994 and April 26, 1994, the Chairman of the Board and
President of Marine wrote to Mr. Bearden suggesting certain terms of a merger
with Chiles. Representatives of Chiles responded to Marine that the Chiles Board
would consider Marine's expression of interest as part of its review of Chiles'
various strategic alternatives but indicated that (i) Chiles had significant
strategic concerns that would not be addressed by a combination with a
contractor whose operations historically have been focused on the Gulf of
Mexico, and (ii) the proposal was not within a range that such representatives
considered fair to the holders of Chiles Common Stock based upon the underlying
asset values and financial prospects of the two companies.
 
     During March 1994, as part of its review of Chiles' strategic alternatives,
representatives of Chiles asked Salomon to contact Noble regarding its interest
in a possible business combination with Chiles. Salomon previously had prepared
a review of Noble's operations, assets and financial condition for the Chiles
Board meeting on February 8, 1994. On March 31, 1994, representatives of Salomon
contacted James C. Day, President, Chairman of the Board and Chief Executive
Officer of Noble, to schedule a meeting for April 10, 1994. The purpose of this
meeting was to discuss areas of mutual interest between Noble and Chiles.
 
     On April 6, 1994, Mr. Day met with representatives of Simmons to prepare
for the upcoming discussions with Chiles. Noble engaged Simmons to develop an
analysis of various acquisition opportunities, including Chiles, for subsequent
presentation to the Board of Directors of Noble.
 
     On April 10, 1994, Mr. Day met with representatives of Salomon and
discussed Noble's interest in pursuing discussions with representatives of
Chiles concerning a merger or similar acquisition transaction.
 
                                       19
<PAGE>   32
 
     In response to Mr. Day's discussion with Salomon, Mr. Bearden met with Mr.
Day on April 22, 1994, and discussed the various business advantages that would
result from the combination of the two companies. They agreed on the importance
of consolidation within the drilling industry, as well as the potential
operational benefits of such a combination and the potential for enhancement of
long-term stockholder value for both companies.
 
     On April 28, 1994 and May 3, 1994, Mr. Bearden and Mr. Day met again and
discussed generally Chiles' operations and its fleet and the potential
operational benefits of a business combination.
 
     On May 4, 1994, Noble management met with representatives of Simmons to
discuss the preliminary information that had been developed by Simmons relative
to acquisition opportunities. On May 10, 1994, management of Noble met again
with representatives of Simmons to review the various analyses that had been
performed relating to several different acquisition opportunities.
 
     On May 13, 1994, the Board of Directors of Noble held a telephonic meeting
to review the financial analyses which had been developed by Simmons. After
thorough review of all the acquisition opportunities, the Board instructed Mr.
Day to contact Mr. Bearden and express Noble's interest in proceeding with
discussions with Chiles regarding a possible acquisition. Mr. Day forwarded a
letter to Mr. Bearden to indicate formally Noble's interest in commencing
discussions with Chiles regarding a merger of the two companies.
 
     On May 16, 1994, Mr. Day met with Mr. Bearden, Mr. Wyman and John Slayton,
a member of the Chiles Board, to discuss further various issues concerning a
potential business combination of Noble and Chiles. The Chiles Board met later
on May 16, 1994, together with representatives of Salomon, to discuss the
indications of interest from Noble and Marine, as well as Chiles' other
alternatives for achieving its strategic goals. On May 17, 1994, Mr. Day met
with Marc Leland and Charles Dallara, two members of the Chiles Board.
Discussions generally centered on the potential synergies that could result from
the combination of the companies and the anticipated enhancement of stockholder
value. The Chiles Board met later on May 17, 1994 to discuss the proposed
transactions, and directed management to continue discussions with Noble
regarding a possible transaction. At this meeting Mr. Leland was elected
Chairman of the Board of Chiles replacing Mr. Wyman.
 
     Mr. Bearden responded in writing to Noble's indication of interest on May
18, 1994, proposing certain business terms and the execution of confidentiality
agreements. The letter further suggested a schedule for conducting due diligence
review. Chiles and Noble entered into mutual confidentiality agreements on May
19, 1994, and commenced a period of mutual due diligence. Mr. Day and Mr.
Bearden met again on May 24 and May 31, 1994, to review the progress of their
due diligence efforts.
 
     On June 1, 1994, the Chiles Board held a telephonic meeting during which
Mr. Bearden and Mr. Fulton reported to the Board on the preliminary results of
their due diligence regarding Noble. Mr. Bearden and Mr. Fulton recommended
proceeding with discussions to resolve the basic business terms of the proposed
merger, and the Board approved their continued discussions. Discussions
continued between Mr. Day and Mr. Bearden on June 2 and 3, 1994.
 
     On June 6, 1994, Mr. Day met with Mr. Leland in Washington D.C. to discuss
various business issues relating to the proposed merger.
 
     On June 9, 1994, a meeting of the Board of Directors of Noble was held in
Houston, Texas to review the results of the due diligence process. At that time
an internal analysis developed by Noble management was presented to the Board
for discussion. Representatives of Simmons presented information relative to
Simmons' analysis of Chiles. Simmons gave the Noble Board its oral opinion that
the consideration proposed to be paid by Noble to the stockholders of Chiles was
fair, as of such date, from a financial point of view to the stockholders of
Noble. After deliberation and discussion, the Board voted unanimously to (i)
approve the Merger and the proposed form of merger agreement, and (ii) approve
exchange ratios of 0.75 of a share of Noble Common Stock for each share of
Chiles Common Stock and one share of $1.50 Noble Preferred Stock for each share
of Chiles Preferred Stock. The Board directed Noble management to proceed with
negotiating and resolving the remaining open business issues and finalizing a
definitive merger agreement. Mr. Day
 
                                       20
<PAGE>   33
 
contacted Mr. Bearden, informed him of the decision by the Noble Board of
Directors and provided him additional information regarding certain business
terms.
 
     The Chiles Board met by telephone on Friday, June 10, 1994 to review the
discussions with Noble during the preceding week and the status of open business
issues regarding the transaction. Mr. Bearden and Mr. Fulton advised the Board
of the results of the Noble Board meeting the previous day as well as the status
of due diligence and negotiations. The Board authorized Mr. Bearden and Mr.
Fulton to seek to finalize the remaining open issues over the weekend. Mr.
Leland called Mr. Day to inform him of the Chiles Board's decision.
 
     Negotiations continued on Saturday and Sunday, June 11 and 12, 1994, during
which time representatives of Noble and Chiles resolved the remaining issues
relating to the proposed merger. On Sunday afternoon, June 12, 1994, the Chiles
Board met again by telephone. Salomon made a presentation to the Board
concerning the terms of the proposed transaction and gave the Board its oral
opinion that the proposed consideration was fair, as of such date, to the Chiles
stockholders from a financial point of view. The Chiles Board unanimously
approved the proposed merger agreement. The Merger Agreement was executed as of
June 13, 1994.
 
REASONS FOR THE MERGER
 
     Noble and Chiles. The Boards of Directors of Noble and Chiles considered
certain common factors in determining that the Merger is in the best interests
of the stockholders of Noble and Chiles, respectively, including the following:
 
     - the business and financial prospects of a Noble/Chiles combination,
       including the size of the combined fleet, the potential operational
       benefits in the Gulf of Mexico and West Africa and the outlook for the
       respective fleets;
 
     - the geographic diversification of a combined Noble/Chiles drilling rig
       fleet consisting of 44 mobile offshore units with significant operational
       bases in the Gulf of Mexico, West Africa and Venezuela and the prospects
       for expansion into other significant oil and gas regions;
 
     - the balance sheet strength of a Noble/Chiles combination and the modest
       debt levels relative to the combined equity of the two companies;
 
     - the outlook for the offshore drilling industry internationally and in the
       Gulf of Mexico and other economic and market conditions, including oil
       and natural gas prices;
 
     - the structure of the Merger, the terms of the Merger Agreement and the
       exchange ratios, which were the result of arms'-length negotiations
       between Noble and Chiles;
 
     - the financial analyses and opinions of their financial advisors; and
 
     - the expectation that the Merger would be a non-taxable transaction for
       U.S. federal income tax purposes.
 
     In addition, the Boards of Directors of Noble and Chiles considered certain
other factors discussed below.
 
     Noble. The Board of Directors of Noble has determined that the consummation
of the Merger is in the best interests of Noble and its stockholders. The Noble
Board believes that the combination is a continuation of Noble's objective of
expansion of its offshore drilling rig fleet and should help consolidate the
highly-fragmented offshore drilling industry. Following the Merger, the addition
of Chiles' 13 jackup drilling rigs will increase the size of Noble's fleet to a
total of 44 mobile offshore units, including 32 jackup drilling rigs. The Merger
will also enhance Noble's balance sheet and provide Noble with increased
flexibility and liquidity, thereby improving Noble's ability to expand its
international operations and to better manage both stronger and weaker offshore
drilling markets. The Noble Board believes that the expansion of Noble's
offshore drilling fleet, the enhancement of Noble's balance sheet and the
possible positive impact on Noble's earnings that could result from any
consolidation savings realized in the Merger will enhance Noble's long-term
growth
 
                                       21
<PAGE>   34
 
potential. As a result, the Noble Board believes that the Merger should, over
time, be significantly positive for Noble and its stockholders.
 
     Chiles. The Board of Directors of Chiles believes that the terms of the
Merger are fair to and in the best interests of Chiles and its stockholders and
has unanimously approved the Merger Agreement and recommends approval and
adoption of the Merger Agreement by the holders of Chiles Common Stock.
 
     In reaching its conclusion, the Chiles Board considered the common factors
set forth above and the following additional factors:
 
     - the fact that the exchange ratio for the Chiles Common Stock represented
       a premium over the market prices for Chiles Common Stock during the
       recent period prior to execution of the Merger Agreement;
 
     - the fact that shares of Chiles Preferred Stock would be converted into
       shares of $1.50 Noble Preferred Stock having substantially the same
       rights, privileges, preferences and voting power as the Chiles Preferred
       Stock;
 
     - Noble's commitment to providing integrated drilling services to its
       customers, including turnkey drilling services, as represented by Noble's
       recent acquisition of Triton; and
 
     - the proposed composition of the Board of Directors of Noble after the
       Merger, which would include two members designated by Chiles.
 
In determining that the Merger was fair to and in the best interests of Chiles
and its stockholders, the Board considered these factors, together with the
common factors described above, collectively and did not assign specific or
relative weights to any of such factors.
 
     The Board of Directors of Chiles determined that a merger with Noble was
the best option for achieving the strategic goals of Chiles. The size of the
combined fleet enhances the prospects for the combined company to have multiple
rig operations in new drilling markets not presently served by either company.
In addition, the combination has the immediate advantage of linking Chiles'
fleet to significant operations in Venezuela and increasing the base of its
operations in West Africa. The Board believes that contractors with multiple
rigs in a given region will be in a superior competitive position because of the
fixed costs associated with establishing a base of operations and the
mobilization costs associated with moving rigs between markets. Accordingly, the
Board believes that the size and geographic diversity of the combined fleet will
permit the combined companies to compete more effectively for drilling contracts
around the world and to achieve higher dayrates and utilization for its rigs. In
addition, the Board believes that Noble's recent acquisition of Triton and its
well established North Sea platform management operations demonstrate Noble's
commitment to providing integrated drilling services to its clients. As a
result, the Chiles Board believes that the Merger represents an opportunity for
Chiles' stockholders to participate in a combined enterprise with significantly
greater operational resources and, accordingly, long-term growth potential than
Chiles would have as a stand alone company or on the basis of the other
transactions considered by the Chiles Board.
 
OPINIONS OF FINANCIAL ADVISORS
 
     Noble. Noble retained Simmons to act as its financial advisor and to render
a fairness opinion in connection with the Merger. Simmons rendered its oral
opinion to the Board of Directors of Noble at a meeting on June 9, 1994 that, as
of such date, the consideration to be paid by Noble in the Merger was fair from
a financial point of view to the holders of Noble Common Stock and $2.25 Noble
Preferred Stock. Subsequently, Simmons confirmed this opinion in writing as of
June 13, 1994. The exchange ratios and the other terms of the Merger Agreement
were determined pursuant to arms'-length negotiations between Noble and Chiles.
 
     The full text of Simmons' fairness opinion, dated June 13, 1994, which sets
forth the assumptions made, general procedures followed, matters considered and
limits on the review undertaken, is attached to this Joint Proxy
Statement/Prospectus as Appendix II and is incorporated herein by reference.
Simmons' opinion is directed only to the fairness, from a financial point of
view, to the holders of Noble Common Stock and $2.25
 
                                       22
<PAGE>   35
 
Noble Preferred Stock of the consideration to be paid by Noble in the Merger and
does not constitute a recommendation to any holder of Noble Common Stock as to
how such stockholder should vote on the Merger Proposal. The summary of Simmons'
opinion set forth below is qualified in its entirety by reference to the full
text of such opinion attached as Appendix II. STOCKHOLDERS OF NOBLE ARE URGED TO
READ THE OPINION OF SIMMONS IN ITS ENTIRETY.
 
     In connection with rendering its opinion, Simmons reviewed, analyzed and
relied upon, among other things, the following: (i) the Merger Agreement; (ii)
certain publicly available informational and financial reports of Noble and
Chiles filed with the Commission, including Annual Reports on Form 10-K for each
of the years in the three-year period ended December 31, 1993, Quarterly Reports
on Form 10-Q for the quarter ended March 31, 1994, recent current reports on
Form 8-K and recent prospectuses; (iii) certain near-term forecasts and other
internal information, primarily financial in nature, concerning the business and
operations of Noble, including recent acquisitions, furnished by Noble for the
purpose of Simmons' analysis; (iv) certain near-term forecasts and other
internal information, primarily financial in nature, concerning the business and
operations of Chiles furnished by Chiles for the purpose of Simmons' analysis;
(v) certain publicly available information concerning the price and trading
activity for Noble Common Stock, $2.25 Noble Preferred Stock, Chiles Common
Stock and Chiles Preferred Stock; (vi) certain publicly available information
with respect to certain other companies that Simmons considers to be comparable
to Noble or Chiles ("Comparable Companies") and the trading markets for the
Comparable Companies' securities; (vii) certain publicly available estimates of
the future operating and financial performance of Noble, Chiles and the
Comparable Companies prepared by industry experts unaffiliated with either Noble
or Chiles ("Analysts' Estimates"); and (viii) certain publicly available
information regarding the nature and terms of certain other transactions that
Simmons considered relevant to its inquiry. In addition, Simmons discussed the
foregoing and other matters Simmons deemed relevant to its inquiry with certain
officers and employees of Noble and Chiles.
 
     In performing its analysis and arriving at its opinion, Simmons assumed and
relied upon the accuracy and completeness of all of the financial and other
information provided by Noble and Chiles or publicly available, including
without limitation, information with respect to asset conditions, tax positions,
liability reserves and insurance coverages. Simmons did not independently verify
any of such information. Simmons did not conduct a physical inspection of any of
the properties, equipment or facilities of Noble or Chiles, nor did it make or
obtain any independent valuations or appraisals of such properties, equipment or
facilities, other than Analysts' Estimates. Furthermore, Simmons assumed that
the new series of $1.50 Noble Preferred Stock would have substantially the same
rights, privileges, preferences and voting power as the Chiles Preferred Stock
and that the Merger would be treated as a "pooling of interests" in accordance
with generally accepted accounting principles.
 
     In conducting its analysis and arriving at its opinion, Simmons considered
such financial and other factors that it deemed appropriate under the
circumstances including, among others, the following: (i) the historical and
current financial position and operating results of Noble and Chiles; (ii) the
business prospects of Noble and Chiles; (iii) the financial performance and
historical and current market for the equity securities of Noble, Chiles and
Comparable Companies; (iv) the relative value of the assets of Noble and Chiles,
based upon Analysts' Estimates and each company's balance sheet; and (v) the
nature and terms of certain other transactions that Simmons considered relevant.
Simmons' analyses reflected recent acquisitions and current capitalization
structures of Noble and Chiles. Simmons also took into account its assessment of
general economic, market and financial conditions, and its experience in
connection with similar transactions and securities valuation generally.
Simmons' opinion necessarily was based upon conditions as they existed and could
be evaluated on, and on the information made available at, the date of such
opinion.
 
     In connection with its presentation to the Noble Board on June 9, 1994,
Simmons advised the Noble Board that in evaluating the consideration to be paid
in the Merger by Noble, Simmons performed a variety of financial and comparative
analyses with respect to Noble and Chiles, including those described below:
 
     Exchange Ratio Profile. Simmons performed an analysis of the ratio of the
market price of Chiles Common Stock to the market price of Noble Common Stock
during the period from the first of January 1991 through the end of May 1994.
Simmons calculated the ratio of the Chiles Common Stock closing price for the
 
                                       23
<PAGE>   36
 
last trading day of each week during that period to the Noble Common Stock
closing price for such day. This analysis implied an exchange ratio ranging from
a high of 1.43 shares of Noble Common Stock for each share of Chiles Common
Stock to a low of 0.21 shares of Noble Common Stock for each share of Chiles
Common Stock, with an average during the period of 0.69 shares of Noble Common
Stock for each share of Chiles Common Stock. Simmons also calculated the ratio
of the Chiles Common Stock closing price on May 27, 1994 ($4.9375 per share) to
the Noble Common Stock closing price on such day ($7.25 per share). This implied
an exchange ratio of 0.68 shares of Noble Common Stock for each share of Chiles
Common Stock.
 
     Premium Analysis. Simmons calculated the premium to holders of Chiles
Common Stock of the "Implied Consideration" (obtained by multiplying the closing
stock price for Noble Common Stock on May 27, 1994 by the exchange ratio of
0.75) to the closing stock prices for Chiles Common Stock on such date and on
the dates one month, three months and 12 months prior thereto as well as to the
weekly average closing price for Chiles Common Stock during the latest 12 months
and to each of the 52-week high and low closing prices for Chiles Common Stock.
Based on the closing stock price for Noble Common Stock of $7.25 on May 27,
1994, Simmons calculated premiums to holders of Chiles Common Stock equal to
10.1 percent of the closing stock price for Chiles Common Stock of $4.9375 on
May 27, 1994; 24.3 percent of the closing stock price for Chiles Common Stock of
$4.375 one month earlier; 1.2 percent of the closing stock price for Chiles
Common Stock of $5.375 three months earlier; 27.9 percent of the closing stock
price for Chiles Common Stock of $4.25 12 months earlier; 2.9 percent of the
weekly average closing price for Chiles Common Stock during the latest 12 months
of $5.28; and a negative 23.7 percent and a positive 50.0 percent of the 52-week
high and low closing prices for Chiles Common Stock of $7.125 and $3.625,
respectively.
 
     Simmons also analyzed average acquisition premiums for acquisitions of
certain comparable public companies in the years 1987 through 1994. The average
premium to last closing price prior to announcement of such transactions for the
transactions occurring during any year ranged from a low of 24.0 percent to a
high of 41.6 percent, with the weighted average being 31.5 percent as compared
with the premium for the merger of 10.1 percent, based on a closing price of
$4.9375 per share for Chiles Common Stock and $7.25 per share for Noble Common
Stock on May 27, 1994.
 
     Relative Contribution Analysis. Simmons analyzed the relative contributions
of Noble and Chiles to, among other things, the combined pro forma historical
and projected revenues, earnings before depreciation and amortization, interest
and taxes ("EBDIT"), net income, total assets and shareholders' equity of the
two companies. The analysis assumes a full period of financial results for
recent acquisitions, completion of the Merger and, in some cases, a certain
level of combination savings. Based on results for the trailing 12 months ended
March 31, 1994 ("TTM"), Simmons calculated contributions by Chiles of
approximately 18 percent of combined revenues, 28 percent of combined EBDIT, 39
percent of combined net income, 26 percent of total assets, 35 percent of
shareholders' equity and 21 percent of "Adjusted Total Book Capitalization" (the
total book capitalization less cash balances in excess of five percent of
operating revenues). Based on the mean of Analysts' Estimates, Simmons
calculated contributions by Chiles of approximately 37 percent of projected
fiscal 1994 net income and 30 percent of projected fiscal 1995 net income.
 
     Based on the Implied Consideration, Simmons calculated contributions by
Chiles of approximately 37 percent of the market value of common equity, 39
percent of the market value of common and preferred equity, 33 percent of the
total market capitalization and 29 percent of the "Adjusted Total Market
Capitalization" (the total market capitalization less cash balances in excess of
five percent of operating revenues).
 
     Valuation Multiple Analysis. Simmons calculated multiples of the $4.9375
closing price per share of Chiles Common Stock and the Implied Consideration to
Chiles' 1993, TTM and estimated 1994 earnings per share (based on both developed
assumptions and Analysts' Estimates). Simmons also calculated multiples of
Chiles' Adjusted Total Market Capitalization, using the $4.9375 closing price
and the Implied Consideration, to Adjusted Total Book Capitalization and 1993,
TTM and estimated 1994 revenues and EBDIT.
 
     These calculations resulted in multiples of the $4.9375 closing price and
the Implied Consideration, respectively, to 1993 earnings per share of 39.5x and
43.5x, respectively, and to estimated 1994 earnings per share (based on the mean
of Analysts' Estimates) of 17.6x and 19.4x, respectively. Calculated multiples
of
 
                                       24
<PAGE>   37
 
Chiles' Adjusted Total Market Capitalization, using the $4.9375 closing price
and the Implied Consideration, to 1993 revenues are 3.0x and 3.4x, respectively;
to 1993 EBDIT are 10.9x and 12.3x, respectively; and to Adjusted Total Book
Capitalization are 1.8x and 2.1x, respectively.
 
     The same multiples were also calculated for Noble at the $7.25 closing
price and for the combined company of Noble and Chiles assuming the $7.25
closing price for Noble, the Implied Consideration for Chiles and, in some
cases, a certain level of combination savings. These calculations resulted in
multiples of Noble and the combined company, respectively, to 1993 earnings per
share of 31.5x and 31.2x, respectively, and to estimated 1994 earnings per share
(based on the mean of Analysts' Estimates) of 18.1x and 17.6x, respectively.
Calculated multiples of Noble and the combined company's Adjusted Total Market
Capitalization, using the $7.25 closing price for Noble and the Implied
Consideration, to 1993 revenues are 1.7x and 2.0x, respectively; to 1993 EBDIT
are 9.2x and 9.7x, respectively; and to Adjusted Total Book Capitalization are
1.3x and 1.5x, respectively.
 
     Analysis of Selected Publicly-Traded Comparable Companies. Simmons reviewed
certain publicly available financial, operating and stock market information as
of May 27, 1994 for Noble, Chiles and the "Comparable Companies" (certain other
publicly-traded offshore drilling companies which Simmons considers to be
comparable to Noble or Chiles). For Noble, Chiles and the Comparable Companies,
Simmons calculated, among other things, multiples of market stock price to TTM
earnings per share and to estimated 1994 and 1995 earnings per share (derived
from Analysts' Estimates) and multiples of Adjusted Total Market Capitalization
to TTM revenues, to TTM EBDIT and to Adjusted Total Book Capitalization.
 
     An analysis of the multiples of market stock price to TTM earnings per
share, to estimated 1994 earnings per share and to estimated 1995 earnings per
share yielded 20.6x, 17.6x and 10.1x, respectively, for Chiles (22.7x, 19.4x and
11.1x, respectively, at the Implied Consideration), 24.1x, 18.1x and 10.5x for
Noble, and means of 20.5x, 20.2x and 17.3x for the Comparable Companies. An
analysis of the multiples of Adjusted Total Market Capitalization to TTM
revenues yielded 2.7x for Chiles (3.1x at the Implied Consideration), 1.7x for
Noble and a mean of 2.6x for the Comparable Companies. An analysis of the
multiples of Adjusted Total Market Capitalization to TTM EBDIT yielded 8.8x for
Chiles (10.0x at the Implied Consideration), 8.9x for Noble and a mean of 10.9x
for the Comparable Companies. An analysis of the multiples of Adjusted Total
Market Capitalization to Adjusted Total Book Capitalization yielded 1.8x for
Chiles (2.1x at the Implied Consideration), 1.3x for Noble and a mean of 1.6x
for the Comparable Companies.
 
     Analysis of Selected Comparable Transactions. Simmons reviewed several
transactions involving the acquisition of oil service companies. Simmons
calculated multiples of acquisition price, or transaction value, to the EBDIT
generated in the 12 months prior to acquisition, and to the Adjusted Total Book
Capitalization of such companies. These calculations yielded a range of
acquisition price to EBDIT of 6.8x to 17.3x, with a mean excluding the high and
the low value of 8.9x, and a range of acquisition price to Adjusted Total Book
Capitalization of 0.8x to 2.8x, with a mean excluding the high and low value of
1.9x. The average transaction EBDIT multiple of 8.9x (excluding the high and low
value) compares to an 8.8x TTM EBDIT multiple for Chiles (10.0x at the Implied
Consideration) and an 8.9x multiple for Noble. The average transaction Adjusted
Total Book Capitalization multiple of 1.9x (excluding the high and low value)
compares to a 1.8x multiple for Chiles (2.1x at the Implied Consideration) and a
1.3x multiple for Noble.
 
     In addition to reviewing company acquisitions, Simmons analyzed recent
purchases of a similar class of jackups as owned by Noble and Chiles. Simmons
calculated the purchase price paid per jackup in each transaction. These
calculations yielded an average price per jackup of $16.7 million. The
consideration paid in the majority of the transactions reviewed was in the form
of cash. Assuming the Implied Consideration and after making working capital
adjustments, the effective average price per jackup that Noble is paying for the
Chiles rigs is approximately three percent higher than the average transaction
price, with the consideration paid in stock.
 
     Discounted Cash Flow Analysis. Simmons performed various discounted cash
flow valuations of Noble and Chiles. Net present values were based on projected
future free cash flows of the companies for five years and a terminal value
calculated assuming the perpetuity method and an inflationary growth rate after
the five-year period of three percent per year. Recently acquired Triton was
excluded from the cash flows analyses and
 
                                       25
<PAGE>   38
 
its purchase price was added to Noble's value. The sums of future cash flows in
perpetuity were then discounted to present values by examining discount rates
ranging from 11 percent to 15 percent and by applying discount rates ranging
from 12 percent to 14 percent. Based on these calculations, Simmons then derived
ranges of present values per share for Noble Common Stock and Chiles Common
Stock.
 
     The purpose of the analysis was to determine the value of each entity, both
on a stand-alone basis and relative to the other. Combination savings were not
incorporated into the analysis. Due to the many variables, the discounted cash
flow analysis yielded a fairly wide range of results. For Chiles, the $4.9375
closing price and the Implied Consideration are within or below the share price
ranges implied by the cases. For Noble, the $7.25 closing price is also within
or below the share price ranges implied by the cases.
 
     The foregoing summary does not purport to be a complete description of the
analyses performed by Simmons or of its presentations to the Noble Board. The
preparation of financial analyses and fairness opinions is a complex process and
is not necessarily susceptible to partial analysis or summary description.
Simmons believes that its analyses (and the summary set forth above) must be
considered as a whole, and that selecting portions of such analyses and of the
factors considered by Simmons, without considering all of such analyses and
factors, could create an incomplete view of the processes underlying the
analyses conducted by Simmons and its opinion. Simmons made no attempt to assign
specific weights to particular analyses. Any estimates contained in Simmons'
analyses are not necessarily indicative of actual values, which may be
significantly more or less favorable than as set forth therein. Estimates of
values of companies do not purport to be appraisals or necessarily reflect the
prices at which companies may actually be sold. Because such estimates are
inherently subject to uncertainty, Simmons does not assume responsibility for
their accuracy.
 
     Simmons is a specialized energy-related investment banking firm engaged in,
among other things, the valuation of businesses and their securities in
connection with mergers and acquisitions, the management and underwriting of
sales of equity and debt to the public and private placements of equity and
debt. Noble selected Simmons to act as its financial advisor in connection with
the Merger on the basis of Simmons' expertise in the oil and gas service and
equipment industry.
 
     Pursuant to an engagement letter with Simmons, Noble has agreed to pay
Simmons a transaction fee, payable on the consummation of the Merger, of
$1,350,000. Noble has also agreed to reimburse Simmons for certain expenses
incurred in connection with its engagement and to indemnify Simmons and certain
related persons against certain liabilities and expenses relating to or arising
out of its engagement, including certain liabilities under the federal
securities laws.
 
     Simmons has in the past rendered investment banking services to Noble,
including acting as advisor in connection with certain acquisitions and as an
underwriter of Noble's 1993 public offerings of Noble Common Stock and 9 1/4%
Senior Notes Due 2003, and has received customary compensation for such
services. In addition, in the ordinary course of business, Simmons may actively
trade the securities of Noble and Chiles for its own account and for the
accounts of customers and, accordingly, may at any time hold a long or short
position in such securities.
 
     Chiles. Chiles retained Salomon to act as financial advisor and render a
fairness opinion in connection with the Merger. Salomon rendered an oral opinion
to the Chiles Board of Directors on June 12, 1994, that the consideration to be
received by the holders of Chiles Common Stock and Chiles Preferred Stock
pursuant to the Merger Agreement was fair to such holders from a financial point
of view.
 
     The full text of Salomon's fairness opinion, dated June 13, 1994, which
sets forth the assumptions made, general procedures followed, matters considered
and limits on the review undertaken, is attached as Appendix III to this Joint
Proxy Statement/Prospectus. Salomon's opinion is directed only to the fairness,
from a financial point of view, to the holders of Chiles Common Stock and Chiles
Preferred Stock to be received by such holders in the Merger, and does not
constitute a recommendation to any holder of the Chiles Common Stock as to how
such stockholder should vote on the Merger Agreement. The summary of Salomon's
opinion set forth below is qualified in its entirety by reference to the full
text of such opinion attached as Appendix III hereto. STOCKHOLDERS ARE URGED TO
READ SALOMON'S OPINION IN ITS ENTIRETY.
 
                                       26
<PAGE>   39
 
     In connection with rendering its opinion, Salomon reviewed, analyzed and
relied upon material relating to the financial and operating condition of Chiles
and Noble, including, among other things, the following: (i) the Merger
Agreement; (ii) certain publicly available information concerning Chiles,
including the Annual Reports on Form 10-K of Chiles for each of the three years
in the three year period ended December 31, 1993 and the Quarterly Report on
Form 10-Q of Chiles for the quarter ended March 31, 1994; (iii) certain internal
information, primarily historical financial in nature, concerning the business
and operations of Chiles furnished by Chiles to Salomon for the purposes of its
analysis; (iv) certain publicly available information concerning the trading of,
and the trading market for, Chiles Common Stock; (v) certain publicly available
information concerning Noble, including the Annual Reports on Form 10-K of Noble
for each of the three years in the three year period ended December 31, 1993 and
the Quarterly Report on Form 10-Q of Noble for the quarter ended March 31, 1994;
(vi) certain internal information, primarily historical financial in nature,
concerning the business and operations of Noble furnished by Noble to Salomon
for the purposes of its analysis; (vii) certain publicly available information
concerning the trading of, and the trading market for, Noble Common Stock;
(viii) certain publicly available information with respect to certain other
companies that Salomon believes to be comparable to Chiles or Noble and the
trading markets for certain of such other companies' securities; and (ix)
certain publicly available information concerning the nature and terms of
certain other transactions that Salomon considered relevant to its inquiry.
Salomon also met with certain officers and employees of Chiles and Noble to
discuss the foregoing as well as other matters Salomon deemed relevant to its
inquiries.
 
     In its review and analysis and in arriving at its opinion, Salomon assumed
and relied upon the accuracy and completeness of all of the financial and other
information provided to it or publicly available, and did not attempt
independently to verify any of such information. Salomon did not conduct a
physical inspection of any of the properties or facilities of Chiles or Noble,
nor did it make or obtain any independent appraisals of any of such properties
or facilities. Salomon assumed that the $1.50 Noble Preferred Stock will have
substantially identical rights, privileges, preferences and voting power as
those of the Chiles Preferred Stock, that the Merger will not be taxable for the
holders of Chiles Common Stock and Chiles Preferred Stock and that the Merger
will be accounted for as a "pooling of interests."
 
     In conducting its analysis and arriving at its opinion, Salomon considered
such financial and other factors as it deemed appropriate under the
circumstances including, among others, the following: (i) the historical and
current financial position and results of operations of Chiles and Noble; (ii)
the business prospects of Chiles and Noble; (iii) the historical and current
trading market for Chiles Common Stock, for Noble Common Stock and for the
equity securities of certain other companies that Salomon believed to be
comparable to Chiles and Noble; and (iv) the nature and terms of certain other
acquisition transactions that Salomon believed to be relevant. Salomon also took
into account its assessment of general economic, market and financial conditions
and its experience in connection with similar transactions and securities
valuation generally. Salomon's opinion necessarily was based on conditions as
they existed and could be evaluated on the date of its opinion.
 
     In connection with its presentation to the Board of Directors of Chiles on
June 12, 1994, Salomon advised the Board that, in evaluating the consideration
to be received in the Merger by the holders of Chiles Common Stock and Chiles
Preferred Stock, Salomon performed a variety of financial analyses with respect
to Chiles and Noble.
 
     Exchange Ratio Profile. Salomon performed an analysis of the historical
ratio of the market price of Chiles Common Stock to the market price of Noble
Common Stock during the period from January 1, 1993 through June 9, 1994.
Salomon calculated the ratio of the Chiles Common Stock closing price for each
trading day during that period to the Noble Common Stock closing price for such
day. This analysis implied an exchange ratio ranging from a low of 0.28 of a
share of Noble Common Stock to each share of Chiles Common Stock to a high of
0.81 of a share of Noble Common Stock to each share of Chiles Common Stock, with
an average during the period of 0.59 of a share of Noble Common Stock to each
share of Chiles Common Stock. Salomon performed the same analysis for the period
from June 10, 1993 through June 9, 1994, which implied an exchange ratio ranging
from a low of 0.48 of a share of Noble Common Stock to each share of Chiles
Common Stock to a high of 0.81 of a share of Noble Common Stock to each share of
Chiles Common
 
                                       27
<PAGE>   40
 
Stock, with an average during the period of 0.64 of a share of Noble Common
Stock to each share of Chiles Common Stock; for the period from January 1, 1994
through June 9, 1994, which implied an exchange ratio ranging from a low of 0.50
of a share of Noble Common Stock to each share of Chiles Common Stock to a high
of 0.81 of a share of Noble Common Stock to each share of Chiles Common Stock,
with an average during the period of 0.65 of a share of Noble Common Stock to
each share of Chiles Common Stock; and for the period from May 10, 1994 through
June 9, 1994, which implied an exchange ratio ranging from a low of 0.59 of a
share of Noble Common Stock to each share of Chiles Common Stock to a high of
0.74 of a share of Noble Common Stock to each share of Chiles Common Stock, with
an average during the period of 0.67 of a share of Noble Common Stock to each
share of Chiles Common Stock. Salomon also calculated the ratio of the Chiles
Common Stock price on June 9, 1994 ($5.00 per share) to the Noble Common Stock
price on such day ($7.125 per share). This implied an exchange ratio of 0.70 of
a share of Noble Common Stock to each share of Chiles Common Stock.
 
     Premium Analysis. Salomon calculated the premium to holders of Chiles
Common Stock of the "Implied Consideration" (represented by multiplying the
closing stock price for Noble Common Stock on June 9, 1994 by the Exchange Ratio
of 0.75) to the closing stock prices for Chiles Common Stock on such date and on
the date one month prior thereto, as well as to the average closing stock price
for Chiles Common Stock during the one month period ending on June 9, 1994 and
to each of the 52 week high and low closing prices for Chiles Common Stock.
Based upon the closing stock price for Noble Common Stock of $7.125 on June 9,
1994, Salomon calculated premiums to holders of Chiles Common Stock equal to
seven percent of the closing stock price for Chiles Common Stock of $5.00 on
June 9, 1994; 26 percent of the closing stock price for Chiles Common Stock of
$4.25 one month earlier, 14 percent of the average closing stock price for
Chiles Common Stock for the one-month period ending on June 9, 1994; and (25
percent) and 47 percent of the 52 week high and low closing prices,
respectively, for Chiles Common Stock.
 
     Salomon also calculated multiples of Chiles' "Implied Firm Value" (defined
as the aggregate offer price for the common equity, calculated using the Implied
Consideration, plus liquidation value of Chiles Preferred Stock and book values
of total debt and minority interest, less cash and cash equivalents) to its
latest 12 months ("LTM") revenues, its LTM earnings before interest, taxes,
depreciation and amortization ("EBITDA") and its latest quarter annualized
EBITDA; and of the Implied Consideration to estimated Chiles earnings per share
and cash flow per share for calendar years 1994 and 1995 (based on the median of
published estimates reported by oil service industry research analysts). The
results of these calculations were as follows: Implied Firm Value to LTM
Revenues of 3.0x, to LTM EBITDA of 9.4x and to latest quarter annualized EBITDA
of 9.7x, and Implied Consideration to estimated 1994 earnings per share of
21.4x, to estimated 1995 earnings per share of 10.7x, to estimated 1994 cash
flow per share of 10.7x, and to estimated 1995 cash flow per share of 7.1x.
 
     Financial Performance Analysis. Salomon analyzed the relative contributions
of Chiles and Noble to, among other financial measures, the combined revenues,
EBITDA, net income and cash flow of the two companies based on 1993 results; the
total assets, total debt and stockholders' equity as of March 31, 1994 of the
two companies; and the estimated 1994 and 1995 net income and cash flow (based
on the median of published estimates reported by oil service industry research
analysts) of the two companies, assuming completion of the Merger (without
giving effect to any transaction adjustments). Salomon calculated contributions
by Chiles of approximately 17 percent of combined 1993 revenues; 23 percent of
combined 1993 EBITDA; 30 percent of combined 1993 net income; 24 percent of
combined 1993 cash flow; 27 percent of combined total assets; 0 percent of
combined total debt; 37 percent of combined stockholders' equity; 39 percent of
combined estimated 1994 net income; 38 percent of combined estimated 1995 net
income; 31 percent of combined estimated 1994 cash flow; and 32 percent of
combined estimated 1995 cash flow. Salomon also calculated the percentage (using
the Exchange Ratio of 0.75 and assuming completion of the Merger) of the
combined companies' equity that would be held by former Chiles stockholders
assuming no conversion of the $2.25 Noble Preferred Stock into Noble Common
Stock, assuming full conversion of the $2.25 Noble Preferred Stock into Noble
Common Stock and assuming full conversion of both the $2.25 Noble Preferred
Stock and the Chiles Preferred Stock into Noble Common Stock at 37 percent, 31
percent and 37 percent, respectively, and compared such percentages with the
foregoing contribution percentages.
 
                                       28
<PAGE>   41
 
     Analysis of Selected Publicly-Traded Comparable Companies. Salomon reviewed
certain publicly available financial, operating and stock market information as
of June 9, 1994 for Chiles and Noble, and for certain selected publicly traded
offshore drilling companies ("Comparable Companies"). For each of Chiles and
Noble and each of the Comparable Companies, Salomon calculated, among other
things, multiples of "Firm Value" (defined as the aggregate market value of the
common equity, plus liquidation value of preferred stock and book values of
total debt and minority interest, less cash and cash equivalents) to LTM EBITDA
and to latest quarter annualized EBITDA, and multiples of market price to
estimated 1994 and 1995 earnings per share and cash flow per share (based on the
median of published estimates reported by oil service industry research
analysts). An analysis of the multiples of Firm Value to LTM EBITDA yielded 8.9x
for Chiles (9.4x at the Implied Consideration) and 8.7x for Noble, with a median
for the Comparable Companies of 9.5x. An analysis of the multiples of Firm Value
to latest quarter annualized EBITDA yielded 9.1x for Chiles (9.7x at the Implied
Consideration) and 9.6x for Noble, with a median for the Comparable Companies of
9.3x. An analysis of the multiples of market price to estimated 1994 earnings
per share yielded 20.0x for Chiles (21.4x at the Implied Consideration) and
19.3x for Noble, with a median for the Comparable Companies of 27.5x. An
analysis of the multiples of market price to estimated 1995 earnings per share
yielded 10.0x for Chiles (10.7x at the Implied Consideration) and 11.5x for
Noble, with a median for the Comparable Companies of 17.0x. An analysis of the
multiples of market price to estimated 1994 cash flow per share yielded 10.0x
for Chiles (10.7x at the Implied Consideration) and 8.2x for Noble, with a
median for the Comparable Companies of 9.7x. An analysis of the multiples of
market price to estimated 1995 cash flow per share yielded 6.7x for Chiles (7.1x
at the Implied Consideration) and 6.4x for Noble, with a median for the
Comparable Companies of 7.4x.
 
     Analysis of Selected Comparable Acquisition Transactions. Salomon also
reviewed twenty-two transactions involving the acquisition or proposed
acquisition of all or part of certain oil field service companies. Salomon
calculated the multiples of Firm Value to EBITDA and revenues.
 
     The calculations yielded a range of Firm Value to LTM EBITDA of 4.1x to
15.0x with a median of 8.6x, and a range of Firm Value to LTM revenues of 0.6x
to 3.1x with a median of 1.5x. Salomon then compared the results of these
calculations to multiples calculated using the Implied Firm Value; 9.4x Implied
Firm Value to Chiles' LTM EBITDA and 3.0x Implied Firm Value to Chiles' LTM
revenues.
 
     Discounted Cash Flow Analyses. Salomon performed discounted cash flow
analyses of Chiles and Noble, based on projections of future performance
developed by Salomon, employing two methodologies: the first based on free cash
flow to the entire firm and an estimated terminal value derived as a multiple of
EBITDA ("Firm Value Approach"); the second based on free cash flow to equity and
an estimated terminal value derived as a multiple of net income ("Equity Value
Approach").
 
     The Firm Value Approach applied terminal value multiples ranging from 3.5x
to 5.5x EBITDA. The sums of future cash flows to the firm and the range of such
related terminal value multiples were then discounted to present value by
applying discount rates ranging from 12 percent to 14 percent. Based on these
calculations, Salomon then derived present values per share ranging from $4.69
to $6.46 for Chiles Common Stock and $5.79 to $8.78 for Noble Common Stock.
 
     The Equity Value Approach applied terminal value multiples ranging from
6.0x to 10.0x net income. The sums of future cash flows to equity and the range
of such related terminal values were then discounted to present values by
applying discount rates ranging from 13 percent to 15 percent. Based on these
calculations, Salomon then derived present values per share ranging from $4.55
to $6.61 for Chiles Common Stock, and ranging from $6.81 to $9.78 for Noble
Common Stock.
 
     The foregoing summary does not purport to be a complete description of the
analyses performed by Salomon or of its presentations to the Chiles Board. The
preparation of financial analyses and fairness opinions is a complex process and
is not necessarily susceptible to partial analysis or summary description.
Salomon believes that its analyses (and the summary set forth above) must be
considered as a whole and that selection of sections of such analyses and of the
factors considered by Salomon, without considering all of such analyses and
factors, could create an incomplete view of the processes underlying the
analyses conducted by Salomon and its opinion. Salomon made no attempt to assign
specific weights to particular analyses. Any estimates
 
                                       29
<PAGE>   42
 
contained in Salomon's analyses are not necessarily indicative of actual values,
which may be significantly more or less favorable than as set forth therein.
Estimates of values of companies do not purport to be appraisals or necessarily
to reflect the prices at which companies may actually be sold. Because such
estimates are inherently subject to uncertainty, Salomon does not assume
responsibility for their accuracy.
 
     Salomon is an internationally recognized investment banking firm engaged,
among other things, in the valuation of businesses and their securities in
connection with mergers and acquisitions, restructurings, leveraged buyouts,
negotiated underwritings, competitive biddings, secondary distributions of
listed and unlisted securities, private placements and valuations for estate,
corporate and other purposes. Salomon has previously rendered certain investment
banking and financial advisory services to Chiles and to Noble, including as
lead manager for the public offerings of Chiles Common Stock in November 1992
and Chiles Preferred Stock in October 1993 and as lead manager for the public
offerings of Noble Common Stock and Noble's 9 1/4% Senior Notes Due 2003 in
October 1993, in each case for which it received customary compensation. In
addition, in the ordinary course of its business, Salomon may actively trade the
securities of Chiles and Noble for its own account and for the accounts of
customers and, accordingly, may at any time hold a long or short position in
such securities.
 
     Pursuant to an engagement letter with Salomon, Chiles has agreed to pay
Salomon a fee for its services in connection with the Merger, based on the value
of the Merger (defined as the value of consideration paid to stockholders and
employees of Chiles in connection with such transaction, including stock options
and employee bonuses). The fee will be an amount equal to 1.2 percent of the
first $100 million of the value of such transaction, and 0.75 percent of the
value over $100 million. In addition, Chiles has agreed to reimburse Salomon for
certain expenses incurred in connection with its engagement and to indemnify
Salomon and certain related persons against certain liabilities and expenses
relating to or arising out of its engagement, including certain liabilities
under the Federal securities laws.
 
CERTAIN FEDERAL INCOME TAX CONSEQUENCES
 
     Noble has received from its counsel, Thompson & Knight, A Professional
Corporation ("Counsel"), an opinion to the effect that the Merger will be
treated for federal income tax purposes as a reorganization within the meaning
of Section 368(a) of the Internal Revenue Code of 1986, as amended (the "Code"),
that Noble, Noble Sub and Chiles will each be a party to the reorganization
within the meaning of Section 368(b) of the Code, and that Noble, Noble Sub and
Chiles will not recognize any gain or loss as a result of the Merger. It is a
condition to the obligation of Noble to consummate the Merger that the opinion
of Counsel will not have been withdrawn or modified in any material respect.
Chiles has received from its counsel, Vinson & Elkins L.L.P., an opinion to the
effect that the Merger will be treated for federal income tax purposes as a
reorganization within the meaning of Section 368(a) of the Code, that Noble,
Noble Sub and Chiles will each be a party to the reorganization within the
meaning of Section 368(b) of the Code, and that stockholders of Chiles will not
recognize any gain or loss as a result of the Merger, except to the extent they
receive cash in lieu of a fractional share of Noble Common Stock. It is a
condition to the obligation of Chiles to consummate the Merger that such opinion
shall not have been withdrawn or modified in any material respect. The opinions
of counsel to Noble and Chiles are subject to certain assumptions and are based
on certain representations of Noble, Noble Sub, Chiles and affiliates of Chiles.
Stockholders of Chiles should be aware that such opinions will neither be
binding upon the Internal Revenue Service (the "IRS") nor will the IRS be
precluded from adopting a contrary position.
 
     Set forth below is a summary of the material federal income tax
consequences which are expected to result from the Merger. For a discussion of
certain federal income tax consequences regarding the $1.50 Noble Preferred
Stock, see "Description of Noble Capital Stock -- Federal Income Tax
Considerations Regarding $1.50 Noble Preferred Stock." Unless noted otherwise,
statements of legal conclusions set forth in this section and herein under
"Description of Noble Capital Stock -- Federal Income Tax Considerations
Regarding $1.50 Noble Preferred Stock" constitute the opinion of Counsel.
 
     It is impractical to comment on all aspects of federal, state, local and
foreign laws that may affect the tax consequences of the transactions
contemplated by the Merger Agreement as they relate to the particular
 
                                       30
<PAGE>   43
 
circumstances of each stockholder or potential stockholder. The federal income
tax consequences to any particular stockholder may be affected by matters not
discussed below. For example, certain types of holders (including foreign
persons, life insurance companies, tax exempt organizations and taxpayers who
may be subject to the alternative minimum tax) may be subject to special rules
not addressed herein. Furthermore, the discussions may not be applicable with
respect to shares received pursuant to the exercise of employee stock options or
otherwise as compensation. Each stockholder or prospective stockholder should
consult his or her own tax advisor with respect to his or her own particular
circumstances.
 
     This summary is based on the current provisions of the Code, existing and
proposed regulations thereunder and current administrative rulings and court
decisions, all of which are subject to changes that may or may not be
retroactively applied. Many of the provisions of the Code which have been
recently enacted or amended have not been interpreted by the courts or the IRS.
 
     No ruling has been requested from the IRS with respect to any of the
matters discussed herein and thus no assurance can be provided that the opinions
and statements set forth herein (which do not bind the IRS or the courts) will
not be challenged by the IRS or would be sustained by a court if so challenged.
 
     THE DISCUSSION SET FORTH BELOW ADDRESSES THE MATERIAL FEDERAL INCOME TAX
CONSEQUENCES OF GENERAL APPLICATION WHICH ARE EXPECTED TO RESULT FROM THE
MERGER. STOCKHOLDERS OF CHILES SHOULD CONSULT THEIR TAX ADVISORS TO DETERMINE
THE TAX CONSEQUENCES OF THE MERGER AND THE ACQUISITION, HOLDING AND DISPOSITION
OF THE SECURITIES OFFERED HEREBY, INCLUDING THE APPLICABILITY AND EFFECT OF
FEDERAL, STATE, LOCAL AND FOREIGN INCOME AND OTHER TAX LAWS WITH RESPECT TO
THEIR OWN PARTICULAR CIRCUMSTANCES.
 
     Merger. Based on certain factual representations by Noble and Chiles and
certain factual assumptions set forth in its opinion included as an exhibit to
the Registration Statement, Counsel is of the opinion that the Merger will
constitute a reorganization within the meaning of Sections 368(a) of the Code,
that no gain or loss will be recognized by stockholders of Chiles upon the
exchange of their shares of Chiles Common Stock and Chiles Preferred Stock for
shares of Noble Common Stock and $1.50 Noble Preferred Stock pursuant to the
terms of the Merger Agreement (except for gain on cash received in lieu of
fractional shares as discussed below) and that no gain or loss will be
recognized by Chiles, Noble or Noble Sub as a result of the Merger. The
aggregate basis of the shares of Noble Common Stock and $1.50 Noble Preferred
Stock received by stockholders of Chiles pursuant to the Merger will be the same
as the aggregate basis of the shares of Chiles Common Stock or Chiles Preferred
Stock exchanged therefor (less basis attributable to fractional shares
surrendered for cash), and the holding period of such Noble capital stock will
include the period during which such shares of Chiles Common Stock or Chiles
Preferred Stock exchanged therefor were held, provided such shares of Chiles
Common Stock or Chiles Preferred Stock were held as a capital asset at the time
of the Merger.
 
     Receipt of Cash in Lieu of Fractional Shares. Chiles stockholders receiving
cash in lieu of fractional shares will be treated as if such fractional shares
had been received in the Merger and redeemed by Noble for cash. Unless the
redemption is found to be essentially equivalent to a dividend, the stockholder
will recognize gain or loss measured by the difference between the stockholder's
basis in the fractional share surrendered and the amount of cash received.
 
     Tax Consequences to Holders of the Chiles Options. If each holder of the
Chiles Options consents to the exchange of such options for shares of Noble
Common Stock, then such holders will recognize ordinary income equal to the fair
market value of the Noble Common Stock received. If the Chiles Options are not
exchanged pursuant to the Merger Agreement, Noble will assume all outstanding
Chiles Options and substitute options to acquire Noble Common Stock on the same
terms and conditions as the Chiles Options. The foregoing assumption and
substitution of options to acquire Noble Common Stock should not cause the
recognition of income, gain or loss to the option holders. See "Certain
Provisions of the Merger Agreement -- Chiles Options."
 
                                       31
<PAGE>   44
 
ANTICIPATED ACCOUNTING TREATMENT
 
     The Merger is expected to be accounted for as a "pooling of interests" for
accounting and financial reporting purposes. Under the pooling of interests
method of accounting, the recorded assets and liabilities of Noble and Chiles
will be carried forward to Noble's consolidated financial statements at their
recorded amounts, the consolidated earnings of Noble will include earnings of
Noble and Chiles for the entire fiscal year in which the Merger occurs and the
reported operating results and financial position of Noble and Chiles for prior
periods will be combined and restated as if both the companies had been merged
during all periods presented. See "Unaudited Pro Forma Combined Financial
Statements" and "Certain Provisions of the Merger Agreement -- Certain
Conditions to Consummation of the Merger."
 
     Noble and Chiles have been preliminarily advised by their independent
public accountant, Arthur Andersen & Co., that the Merger should qualify for
treatment as a "pooling of interests" in accordance with generally accepted
accounting principles based on the understanding of Arthur Andersen & Co. of the
terms and conditions of the Merger Agreement. Consummation of the Merger is
conditioned upon the written confirmation of such advice. See "Certain
Provisions of the Merger Agreement -- Certain Conditions to Consummation of the
Merger." Also, such advice contemplates that each person who may be deemed an
affiliate of Chiles or Noble will enter into an agreement with Noble at or
before the Effective Time not to sell or otherwise transfer any shares of Noble
Common Stock prior to the date that Noble first publishes financial statements
reflecting at least 30 days of combined operations of Noble and Chiles. See
"-- Limitations on Resale; Registration Rights." Noble, Noble Sub and Chiles
have agreed that none of them shall knowingly take any action that would
jeopardize the treatment of Chiles' combination with Noble Sub as a "pooling of
interests" for accounting purposes.
 
REGULATORY APPROVALS
 
     Under the HSR Act, and the rules promulgated thereunder by the Federal
Trade Commission (the "FTC"), the Merger may not be consummated until
notifications have been given and certain information has been furnished to the
FTC and the Antitrust Division of the Department of Justice (the "Antitrust
Division") and specified waiting period requirements have been satisfied. Noble
and Chiles filed notification and report forms under the HSR Act with the FTC
and the Antitrust Division on July   , 1994. The respective obligations of Noble
and Chiles to consummate the Merger are conditioned upon all waiting periods
(and any extensions thereof) applicable to the consummation of the Merger under
the HSR Act having expired or been terminated. See "Certain Provisions of the
Merger Agreement -- Certain Conditions to Consummation of the Merger."
 
     At any time before or after consummation of the Merger, and notwithstanding
that the HSR Act waiting period has expired or terminated, the FTC or the
Antitrust Division or any state could take such action under the federal or
state antitrust laws as it deems necessary or desirable in the public interest.
Such action could include seeking to enjoin the consummation of the Merger or
seeking divestiture of Chiles or businesses of Noble or Chiles. Private parties
may also seek to take legal action under the antitrust laws under certain
circumstances.
 
     Based on information available to them, Noble and Chiles believe that the
Merger can be effected in compliance with federal and state antitrust laws.
However, there can be no assurance that a challenge to the consummation of the
Merger on antitrust grounds will not be made or that, if such a challenge were
made, Noble and Chiles would prevail or would not be required to accept certain
conditions, possibly including certain conditions to consummation of the Merger.
 
LIMITATIONS ON RESALES; REGISTRATION RIGHTS
 
     Resales by Affiliates. The shares of Noble Common Stock and $1.50 Noble
Preferred Stock to be issued to the stockholders of Chiles, and shares of Noble
Common Stock to be issued to holders of Chiles Options upon cancellation
thereof, pursuant to the Merger Agreement are being registered under the
Securities Act pursuant to the Registration Statement and may generally be
resold freely without further registration. However, because some of such
persons are "affiliates" of Chiles (as such term is defined in Rule 144 under
 
                                       32
<PAGE>   45
 
the Securities Act), such persons will not be able to resell the Noble Common
Stock or $1.50 Noble Preferred Stock received by them in connection with the
Merger unless such shares are registered for resale under the Securities Act,
are sold in compliance with an exemption from the registration requirements of
the Securities Act or are sold in compliance with Rule 145 under the Securities
Act (or, in the case of persons who become affiliates of Noble, Rule 144 under
the Securities Act). Noble will not be required to maintain the effectiveness of
the Registration Statement for the purpose of such resales.
 
     Pursuant to Rule 145, the sale of Noble Common Stock or $1.50 Noble
Preferred Stock acquired by such persons pursuant to the Merger Agreement will
be subject to certain restrictions. Such persons may sell Noble Common Stock or
$1.50 Noble Preferred Stock under Rule 145 only if (i) Noble has filed all
reports required to be filed by Section 13 or 15(d) of the Exchange Act during
the preceding 12 months, (ii) the Noble Common Stock or $1.50 Noble Preferred
Stock is sold in "brokers' transactions" or in transactions directly with a
"market maker," within the meanings thereof in Rule 144 under the Securities
Act, and (iii) such sale and all other sales made by such person within the
preceding three months do not collectively exceed the greater of (x) one percent
of the then outstanding shares of Noble Common Stock or $1.50 Noble Preferred
Stock, as the case may be, and (y) the average weekly trading volume of Noble
Common Stock or $1.50 Noble Preferred Stock, as the case may be, in the NASDAQ
National Market System during the four-week period preceding the sale.
 
     Persons who may be deemed to be affiliates of Noble or Chiles generally
include individuals or entities that control, are controlled by or are under
common control with, such party and may include certain officers and directors
of such party as well as principal stockholders of such party. The Merger
Agreement requires Chiles to use its reasonable best efforts to cause each
person whom it believes may be an affiliate of Chiles for purposes of Rule 145
to deliver to Noble at or prior to the closing of the Merger a written agreement
to the effect that such person will not, among other things, offer or sell or
otherwise dispose of any shares of Noble Common Stock or $1.50 Noble Preferred
Stock issued to such person pursuant to the Merger in violation of the
Securities Act or the rules and regulations promulgated thereunder by the
Commission. See "Certain Provisions of the Merger Agreement -- Certain
Conditions to Consummation of the Merger."
 
     Registration Rights of P.A.J.W. As of the record date for the Chiles
Special Meeting, P.A.J.W. owned 11,535,587 shares of Chiles Common Stock or
approximately 30 percent of the outstanding shares of such stock. Based on the
capitalization of Noble and Chiles as of such record date, upon consummation of
the Merger, P.A.J.W. will own approximately 11.1 percent of the then outstanding
shares of Noble Common Stock. The Merger Agreement provides that Noble and
P.A.J.W., of which Marc E. Leland, John Slayton and Lawrence Chazen are
affiliates, will enter into a Registration Rights Agreement pursuant to which
P.A.J.W. will be entitled to require Noble to register for sale under the
Securities Act the shares of Noble Common Stock received by P.A.J.W. in
connection with the Merger. In addition, P.A.J.W. will have certain rights to
include such shares in any registration effected by Noble with respect to the
Noble Common Stock. The Registration Rights Agreement will have a five-year
term, and, subject to certain limitations, will entitle P.A.J.W. to two "demand"
registrations and unlimited "piggyback" registrations as described above.
Generally, the Registration Rights Agreement will provide that expenses incurred
in connection with a "demand" registration will be borne by P.A.J.W., and
expenses incurred in connection with a "piggyback" registration, other than
underwriting discounts or commissions applicable to shares sold by P.A.J.W.,
will be borne by Noble.
 
LISTING IN NASDAQ NATIONAL MARKET SYSTEM
 
     Noble Common Stock is currently listed for trading in the NASDAQ National
Market System and it is anticipated that such stock will continue to be traded
thereon immediately following consummation of the Merger. Noble will file a
notice with the National Association of Securities Dealers, Inc. (the "NASD")
with respect to the listing of additional shares of Noble Common Stock to be
issued in respect of shares of Chiles Common Stock, or that may be issued in
respect of the cancellation of Chiles Options, upon consummation of the Merger,
as well as the shares of Noble Common Stock issuable upon conversion of the
$1.50 Noble Preferred Stock and the shares of Noble Common Stock to be reserved
for issuance upon the exercise of Chiles Options to be assumed by Noble in the
Merger, if any. Application will be made to the NASD to list on
 
                                       33
<PAGE>   46
 
the NASDAQ National Market System the shares of $1.50 Noble Preferred Stock to
be issued upon consummation of the Merger. The consummation of the Merger is
conditioned upon NASD approval of such listing.
 
NO APPRAISAL RIGHTS
 
     Stockholders of Chiles are not entitled to any appraisal or dissenter's
rights under the DGCL in connection with the Merger. Stockholders of Noble are
not entitled to any appraisal or dissenter's rights under the DGCL in connection
with the Merger or the other matters to be considered at the Noble Special
Meeting.
 
INTERESTS OF CERTAIN PERSONS IN THE MERGER
 
     In considering the recommendation of the Board of Directors of Chiles with
respect to the Merger, stockholders of Chiles should be aware that certain
persons may have direct or indirect interests in the Merger separate from those
of the stockholders of Chiles generally, including those discussed below.
 
     Representation on Board of Directors. The Merger Agreement provides that
the number of directors comprising Noble's Board of Directors at the Effective
Time will be increased from seven to nine, and that Noble will cause Marc E.
Leland, a director of Chiles, and Lawrence Chazen, an affiliate of P.A.J.W., or
another designee of Chiles, to be elected to the Board of Directors effective as
of the Effective Time. Mr. Leland will be elected to serve until Noble's 1997
annual meeting of its stockholders, and Mr. Chazen will be elected to serve
until Noble's 1996 annual meeting of stockholders.
 
     Marc E. Leland is Chairman of the Board of Directors of Chiles, and has
been a director of Chiles since December 1989. Since 1984, Mr. Leland has served
as President of Marc E. Leland & Associates, Inc., a company engaged in the
business of providing financial advisory services to Gordon P. Getty and certain
Getty family trusts. Mr. Leland is also a director of Caterair International
Corporation. He is the President and sole director of P.A.J.W.
 
     Lawrence Chazen has served as Chief Executive Officer of Lawrence J.
Chazen, Inc., a California registered investment adviser, since 1977, and has
provided financial advisory services to Gordon P. Getty, the Gordon P. Getty
Family Trust and other clients since 1977.
 
     In order to comply with the Bylaws of Noble, which require that each class
of directors be as nearly equal in number as possible, one of the current
members of the Board of Directors of Noble in the class whose term expires at
the 1997 annual meeting of stockholders will become a member of the class whose
term expires at the 1995 annual meeting.
 
     Executive Bonus Arrangements. Pursuant to resolutions adopted by the
Compensation Committee of the Board of Directors of Chiles in May 1993, C. Ray
Bearden, President and a director of Chiles, and Robert F. Fulton, Senior Vice
President and a director of Chiles, will each be entitled to a cash bonus of
$100,000 upon completion of the Merger or another specified business
combination.
 
     Executive Severance Agreements. On July 1, 1993, Chiles entered into
Severance Agreements with C. Ray Bearden and Robert F. Fulton. The Severance
Agreements provide that, in the event of a "Termination Event" within one year
following a specified change in control of Chiles (which would include the
Merger), Chiles will (i) pay to the employee a lump sum payment equal to one
year's annual base salary plus one month's base salary for each year of service
the employee had with Chiles, not to exceed a maximum lump sum payment of two
years' annual base pay, (ii) continue the employee's medical, disability and
life insurance coverage for up to two years or until substantially similar
insurance coverage is provided by a subsequent employer and (iii) accelerate the
vesting of the employee's unvested employee stock options by up to 30 percent. A
"Termination Event" is defined to include (a) a termination other than for cause
(as defined), (b) a material diminution in the scope or nature of the employee's
duties (subject to certain limitations), (c) a reduction in the employee's base
salary of more than 10 percent (with certain exceptions), (d) a diminution in
the employee's ability to participate in employee incentive or benefit plans, or
(e) a required relocation of employee of more than 50 miles from the employee's
then current location.
 
                                       34
<PAGE>   47
 
     Exchange of Options. Pursuant to the Merger Agreement, all outstanding
Chiles Options will be exchanged at the Effective Time for an aggregate of
480,000 shares of Noble Common Stock (subject to adjustment and to the consent
of all holders of such Chiles Options on or prior to the Effective Time). See
"Certain Provisions of the Merger Agreement -- Chiles Options." Pursuant to such
exchange, Messrs. C. Ray Bearden, Robert F. Fulton, Marc E. Leland, Winthrop A.
Wyman, Edward L. Morse, John Slayton and Jack Hilder, each a director of Chiles,
will receive 90,821, 63,575, 13,623, 13,623, 13,623, 13,623 and 13,623 shares of
Noble Common Stock, respectively. If the consent of all holders of the Chiles
Options to the exchange described above is not obtained prior to the closing of
the Merger Agreement, then Noble will take all necessary action to assume such
Chiles Options, substituting Noble Common Stock for the Chiles Common Stock
purchasable thereunder and making other appropriate adjustments as described
under "Certain Provisions of the Merger Agreement -- Chiles Options."
 
     Registration Rights. P.A.J.W. will enter into an agreement with Noble
providing P.A.J.W. certain rights to require Noble to register for sale under
the Securities Act the shares of Noble Common Stock P.A.J.W. receives pursuant
to the Merger. See "-- Limitations on Resale; Registration Rights."
 
     Indemnification. The Merger Agreement provides for broad indemnification of
the officers and directors of Chiles, and obligates Noble to continue for six
years Chiles' directors' and officers' liability insurance. See "Certain
Provisions of the Merger Agreement -- Indemnification."
 
     Employee Benefit Plans. See "Certain Provisions of the Merger
Agreement -- Chiles Employee Benefits" for a discussion of post-Merger
arrangements regarding Chiles employee benefit plans.
 
                   CERTAIN PROVISIONS OF THE MERGER AGREEMENT
 
GENERAL
 
     The Merger Agreement provides that, subject to the terms and conditions set
forth therein, Chiles will be merged with and into Noble Sub, and the separate
existence of Chiles will cease, with Noble Sub continuing in existence as the
surviving corporation and succeeding to all rights, properties and obligations
of Chiles. Following the Merger, Noble Sub will remain a wholly owned subsidiary
of Noble.
 
EFFECTIVE TIME OF THE MERGER; CLOSING
 
     The Merger shall become effective immediately when a certificate of merger,
prepared and executed in accordance with the relevant provisions of the General
Corporation Law of the State of Delaware ("DGCL"), is filed with the Secretary
of State of Delaware or at such time thereafter (not to exceed 90 days from the
date the certificate is filed) as is provided in the certificate of merger
pursuant to the mutual agreement of Noble and Chiles. The filing of the
certificate of merger shall be made as soon as practicable on the Closing Date
(as defined below). The closing of the Merger (the "Closing") shall take place
on a date (the "Closing Date") to be specified by the parties, which shall be as
soon as practicable after the satisfaction or waiver of the conditions to the
consummation of the Merger, unless another date is agreed to by the parties.
 
CONVERSION OF SHARES; PROCEDURE FOR EXCHANGE OF CERTIFICATES; FRACTIONAL SHARES
 
     Subject to the terms and conditions of the Merger Agreement, at the
Effective Time, by virtue of the Merger and without any action on the part of
Noble, Chiles, Noble Sub or their respective stockholders, (i) each share of
Chiles Common Stock issued and outstanding immediately prior to the Effective
Time will be converted into the right to receive 0.75 of a share of Noble Common
Stock and (ii) each share of Chiles Preferred Stock (together with the shares of
Chiles Common Stock issued and outstanding immediately prior to the Effective
Time, the "Shares") will be converted into the right to receive one share of
$1.50 Noble Preferred Stock.
 
     As soon as practicable after the Effective Time, each holder of a
certificate that prior thereto represented Shares will be entitled, upon
surrender thereof to Noble or its transfer agent, to receive in exchange
therefor, as applicable (i) a certificate or certificates representing the
number of whole shares of Noble Common Stock
 
                                       35
<PAGE>   48
 
into which the shares of Chiles Common Stock so surrendered shall have been
converted in such denominations and registered in such names as such holder may
request or (ii) a certificate or certificates representing the number of shares
of $1.50 Noble Preferred Stock into which the shares of Chiles Preferred Stock
so surrendered shall have been converted in such denominations and registered in
such names as such holder may request. Following the Effective Time, Noble will
cause to be mailed to each holder of certificates that represented Shares
immediately prior to the Effective Time, at such holder's address as it appears
on Chile's stock transfer records, a letter of transmittal and other
information, advising such holder of the consummation of the Merger along with
instructions to enable such holder to effect the exchange of stock certificates
as contemplated by the Merger Agreement.
 
     Until so surrendered and exchanged, each certificate that prior to the
Effective Time represented Shares shall represent solely the right to receive
Noble Common Stock (and cash in lieu of fractional shares as described below, if
any) or $1.50 Noble Preferred Stock, as the case may be. Unless and until any
such certificates shall be so surrendered and exchanged, no dividends or other
distributions payable to the holders of Noble Common Stock or $1.50 Noble
Preferred Stock, as of any time on or after the Effective Time, shall be paid to
the holders of such certificates that prior to the Effective Time represented
Shares; provided, however, that, upon any such surrender and exchange of such
outstanding certificates, there shall be paid to the record holders of the
certificates issued and exchanged therefor the amount, without interest thereon,
of dividends and other distributions, if any, that theretofore were declared and
became payable on or after the Effective Time with respect to the number of
whole shares of Noble Common Stock or $1.50 Noble Preferred Stock, as the case
may be, issued to such holder.
 
     All shares of Noble Common Stock and $1.50 Noble Preferred Stock issued
upon the surrender for exchange of certificates that prior to the Effective Time
represented Shares in accordance with the terms of the Merger Agreement
(including any cash paid in lieu of fractional shares, as described below) shall
be deemed to have been issued in full satisfaction of all rights pertaining to
such Shares. At and after the Effective Time, there shall be no further
registration of transfers on the stock transfer books of Noble Sub of the Shares
that were outstanding immediately prior to the Effective Time. If, after the
Effective Time, certificates that prior to the Effective Time represented Shares
are presented to Noble Sub for any reason, they shall be cancelled and exchanged
as provided in the Merger Agreement.
 
     No fractional shares of Noble Common Stock will be issued, and each holder
of Chiles Common Stock who would otherwise be entitled to a fraction of a share
of Noble Common Stock will, upon surrender of the certificates representing
Chiles Common Stock held by such holder to Noble, be paid an amount in cash
equal to the value of such fraction of a share based upon the closing sales
price of Noble Common Stock, as reported on the NASDAQ National Market System,
on the last day on which there is a reported trade in the Noble Common Stock
prior to the date on which the Effective Time occurs. No interest will be paid
on such amount.
 
     If any certificate for shares of Noble Common Stock or $1.50 Noble
Preferred Stock is to be issued in a name other than that in which the
certificate surrendered in exchange therefor is registered, it will be a
condition of the issuance thereof that the certificate so surrendered is
properly endorsed and otherwise in proper form for transfer and that the person
requesting such exchange has paid to Noble or its transfer agent any transfer or
other taxes required by reason of the issuance of a certificate for shares of
Noble Common Stock or $1.50 Noble Preferred Stock in any name other than that of
the registered holder of the certificate surrendered, or has established to the
satisfaction of Noble or its transfer agent that such tax has been paid or is
not payable.
 
     CHILES STOCKHOLDERS SHOULD NOT FORWARD CERTIFICATES REPRESENTING CHILES
COMMON STOCK OR CHILES PREFERRED STOCK TO NOBLE OR ITS TRANSFER AGENT UNTIL THEY
HAVE RECEIVED INSTRUCTIONS AS TO THE MANNER OF SURRENDER. CHILES STOCKHOLDERS
SHOULD NOT RETURN STOCK CERTIFICATES WITH THEIR PROXY.
 
                                       36
<PAGE>   49
 
REPRESENTATIONS AND WARRANTIES
 
     Pursuant to the Merger Agreement, Noble and Chiles each made various
customary representations and warranties as to, among other things, their
respective corporate organization and compliance with law, their respective
capitalization, the authorization and validity of the Merger Agreement, their
respective businesses and financial condition, required approvals or conflicts,
their Commission filings and financial statements, litigation, employee benefit
matters, tax matters and environmental matters.
 
CONDUCT OF BUSINESS PRIOR TO EFFECTIVE TIME
 
     Chiles. Under the Merger Agreement, Chiles has agreed, from the date of the
Merger Agreement until the Effective Time, unless Noble shall otherwise agree in
writing or as otherwise contemplated by the Merger Agreement or as disclosed to
Noble, that, among other things: (a) the business of Chiles shall be conducted
only in the ordinary course of business and consistent with past practice, and
Chiles will not (i) enter any new drilling contracts with respect to any of
Chiles' drilling rigs unless such contracts may reasonably be expected to have a
duration of 90 days or less, or amend in any material respect adverse to Chiles
or Noble any drilling contract or other material contract or agreement, without
giving prior written notice to Noble, or (ii) mobilize any of Chiles' drilling
rigs from the Gulf of Mexico or from the West African coast without giving prior
written notice to Noble; (b) Chiles will not directly or indirectly take any of
a number of specific actions, including (i) the issuance of additional capital
stock, (ii) the amendment of its charter or bylaws, (iii) the splitting,
combining or reclassifying of any outstanding capital stock, (iv) the
declaration, setting aside or payment of any dividend with respect to its
capital stock (except for regular quarterly cash dividends on the Chiles
Preferred Stock), (v) the redemption, purchase or acquisition of its capital
stock or (vi) making any of a number of specified increases or changes in
Chiles' bonus, compensation or employee benefit plans or arrangements; (c)
Chiles will use its reasonable efforts to preserve its business organizations,
any authorizations or similar rights, the services of its current officers and
key employees, the goodwill of those having business relationships with Chiles,
its properties and its levels of insurance coverage; and (d) Chiles will not
make or agree to make capital expenditures that in the aggregate exceed $500,000
(other than planned capital expenditures previously disclosed to Noble).
 
     Noble. Under the Merger Agreement, Noble has agreed, from the date of the
Merger Agreement until the Effective Time, unless Chiles shall otherwise agree
in writing or as otherwise contemplated by the Merger Agreement or as disclosed
to Chiles, that, among other things: (a) the business of Noble shall be
conducted only in the ordinary course of business and consistent with past
practice; (b) Noble will not directly or indirectly take any of a number of
specific actions, including (i) the issuance of additional capital stock, with
certain exceptions, (ii) the amendment of its charter or bylaws, (iii) the
splitting, combining or reclassifying of any outstanding capital stock, (iv) the
declaration, setting aside or payment of any dividend with respect to its
capital stock (except for regular quarterly cash dividends on the $2.25 Noble
Preferred Stock) (v) the redemption, purchase or acquisition of its capital
stock or (vi) the making of any of a number of specified increases or changes in
Noble's bonus, compensation or employee benefit plans or arrangements; (c) Noble
will use its reasonable efforts to preserve its business organizations, any
authorizations or similar rights, the services of its current officers and key
employees, the goodwill of those having business relationships with Noble, its
properties and its levels of insurance coverage; and (d) Noble will not make or
agree to make capital expenditures other than as previously disclosed to Chiles
or those made in the ordinary course of business and consistent with past
practice.
 
SOLICITATION OF THIRD PARTY OFFERS
 
     The Merger Agreement provides that Chiles will not, directly or indirectly,
through any officer, director, employee, representative or agent of Chiles or
any of its subsidiaries, solicit or knowingly encourage, including by way of
furnishing information, the initiation of any inquiries or proposals regarding
(i) any merger, tender offer, sale of shares of capital stock or similar
business combination transactions involving Chiles or its subsidiaries that
would have the effect of causing the holders of Chiles Common Stock immediately
prior to the effectiveness of such proposed transaction to own in the aggregate
less than 50 percent of the shares of the surviving or resulting entity entitled
to vote generally for the election of directors of the surviving or resulting
 
                                       37
<PAGE>   50
 
entity, or (ii) any sale of all or substantially all the assets of Chiles and
its subsidiaries, taken as a whole (collectively, a "Chiles Acquisition
Transaction"). Notwithstanding the foregoing, nothing in the Merger Agreement
prevents the members of the Board of Directors of Chiles, in the exercise of
their fiduciary duties and after consulting with independent counsel, from
considering, negotiating and approving an unsolicited bona fide proposal that
the Board of Directors of Chiles determines in good faith, after consultation
with its financial advisors, may result in a transaction more favorable to
Chiles' stockholders than the transactions contemplated by the Merger Agreement.
If the Board of Directors of Chiles receives a request for confidential
information by a potential bidder for Chiles and the Board of Directors
determines, after consultation with independent counsel, that the Board of
Directors has a fiduciary obligation to provide such information to a potential
bidder, then Chiles may, subject to a confidentiality agreement substantially
similar to that previously executed by Noble, provide such potential bidder with
access to information regarding Chiles. Chiles will promptly notify Noble,
orally and in writing, if any such proposal or offer is made and will, in any
such notice, indicate the identity and terms and conditions of any proposal or
offer, or any such inquiry or contact. Chiles will keep Noble advised of the
progress and status of any such proposals or offers. The obligation of the Board
of Directors of Chiles to convene a meeting of its stockholders and to recommend
the adoption and approval of the Merger Agreement to the stockholders of Chiles
pursuant to the Merger Agreement will be subject to the fiduciary duties of the
directors, as determined by the directors after consultation with their
independent counsel, and nothing contained in the Merger Agreement will prevent
the Board of Directors of Chiles from approving or recommending to the
stockholders of Chiles any unsolicited offer or proposal by a third party if
required in the exercise of their fiduciary duties, as determined by the
directors after consultation with independent counsel.
 
CHILES OPTIONS
 
     Chiles has agreed to use its best efforts to obtain the consent of each
holder of the Chiles Options to the exchange of such holder's options for shares
of Noble Common Stock as described below (and to take any other actions
necessary to permit such exchange). Subject to obtaining the consent of each
holder of the Chiles Options, and further subject to the consummation of the
Merger, at the Effective Time, all then outstanding Chiles Options will be
cancelled in exchange for an aggregate of 480,000 shares of Noble Common Stock
(subject to appropriate reductions if any Chiles Options outstanding on the date
of the Merger Agreement are exercised prior to the Effective Time). The number
of shares of Noble Common Stock to be received by each holder of a Chiles Option
will be based on a formula that provides that all holders of Chiles Options
having the same exercise price per share and vesting schedule will receive the
same number of shares of Noble Common Stock per share of Chiles Common Stock
purchasable under such Chiles Options.
 
     If each of the holders of the Chiles Options has not consented to the
exchange of such Chiles Options prior to the Closing Date, then the Chiles
Options will not be exchanged as provided in the preceding paragraph, and
instead Noble will take such action as is necessary to assume, effective at the
Effective Time, each Chiles Option that remains as of such time unexercised in
whole or in part and to substitute shares of Noble Common Stock as purchasable
under each such assumed option ("Assumed Option"), with such assumption and
substitution to be effected as follows: (a) the Assumed Option will not give the
optionee additional benefits which he did not have under the Chiles Option
before such assumption and will be assumed on the same terms and conditions,
including, without limitation, the vesting schedule, as the Chiles Options being
assumed; (b) the number of shares of Noble Common Stock purchasable under the
Assumed Option will be equal to the number of shares of Noble Common Stock that
the holder of the Chiles Option being assumed would have received (without
regard to any vesting schedule) upon consummation of the Merger had such Chiles
Option been exercised in full immediately prior to consummation of the Merger;
and (c) the per share exercise price of such Assumed Option will be an amount
equal to the per share exercise price of the Chiles Option being assumed divided
by 0.75.
 
     If the Chiles Options are assumed by Noble as described in the preceding
paragraph, Noble will take all corporate action necessary to reserve for
issuance a sufficient number of shares of Noble Common Stock for delivery upon
exercise of the Assumed Options, and, as soon as practicable after the Effective
Time, Noble will file a registration statement on Form S-8 (or other appropriate
form) with respect to the shares of Noble
 
                                       38
<PAGE>   51
 
Common Stock subject to the Assumed Options, and will use its best efforts to
maintain the effectiveness of such registration statement (and maintain the
current status of any prospectus contained therein) for so long as any of the
Assumed Options remain outstanding.
 
     See "The Merger -- Certain Federal Income Tax Consequences" for a
discussion of certain consequences under the Code of the exchange of Chiles
Options for Noble Common Stock.
 
NASDAQ NATIONAL MARKET SYSTEM LISTING
 
     Subject to the adoption by the stockholders of Noble of the Noble Charter
Amendment, Noble will use all reasonable efforts to cause the shares of Noble
Common Stock and $1.50 Noble Preferred Stock to be issued in the Merger, the
shares of Noble Common Stock to be reserved for issuance upon the exercise of
Chiles Options to be assumed by Noble in the Merger, if any, and the shares of
Noble Common Stock issuable upon conversion of the $1.50 Noble Preferred Stock,
all to be approved for listing in the NASDAQ National Market System prior to the
Closing Date.
 
INDEMNIFICATION
 
     The Merger Agreement provides that, from and after the Effective Time,
Noble and Noble Sub, as the surviving corporation, will indemnify, defend and
hold harmless each person who is now, or has been at any time prior to the date
of the Merger Agreement or who becomes prior to the Effective Time, an officer,
director or employee of Chiles or any of its subsidiaries against all losses,
claims, damages, costs, expenses, liabilities or judgments or amounts that are
paid in settlement with the approval of the indemnifying party of or in
connection with any claim, action, suit, proceeding or investigation based in
whole or in part on or arising in whole or in part out of the fact that such
person is or was a director, officer or employee of Chiles or any of its
subsidiaries, whether pertaining to any matter existing or occurring at or prior
to the Effective Time and whether reasserted or claimed prior to, or at or
after, the Effective Time, including all indemnified liabilities based in whole
or in part on, or arising in whole or in part out of, or pertaining to the
Merger Agreement or the transactions contemplated thereby.
 
     The Merger Agreement provides that Noble Sub, as the surviving corporation,
will purchase and maintain for a period of six years after the Effective Time,
continuation coverage for Chiles' directors' and officers' liability insurance
policy as in effect on the date of the Merger Agreement, or obtain a directors'
and officers' insurance policy with comparable coverage.
 
CHILES EMPLOYEE BENEFITS
 
     The Merger Agreement provides that after the Effective Time, Noble will
provide those employees of Chiles and its subsidiaries covered by the benefit
plans of Chiles and its subsidiaries with the same benefits in respect of future
service that accrue in respect of future services to the employees of Noble who
are employed in comparable positions, and any present employees of Chiles and
its subsidiaries will be credited for their service with Chiles for purposes of
eligibility, benefit entitlement and vesting in the plans provided by Noble
(other than for purposes of benefit accruals under any defined benefit pension
plan).
 
REGISTRATION RIGHTS AGREEMENT
 
     The Merger Agreement provides that, on or prior to the Closing Date, Noble
will execute and deliver to P.A.J.W. a Registration Rights Agreement as
described under "-- Limitations on Resale; Registration Rights."
 
CERTAIN CONDITIONS TO CONSUMMATION OF THE MERGER
 
     The respective obligations of each party to effect the Merger are subject
to the fulfillment at or prior to the Closing Date of a number of conditions set
forth in the Merger Agreement, including: (a) the requisite approval by the
stockholders of Chiles and Noble with respect to the Merger Agreement, and the
requisite approval by the stockholders of Noble with respect to the Noble
Charter Amendment; (b) the termination or
 
                                       39
<PAGE>   52
 
expiration of the waiting period (and any extension thereof) applicable to the
consummation of the Merger under the HSR Act; (c) the Registration Statement,
and any amendments thereto, shall have been declared effective by the Commission
as of the Closing Date; (d) no order shall have been entered and remain in
effect in any action or proceeding before any foreign, federal or state court or
governmental agency or other foreign, federal or state regulatory or
administrative agency or commission that would prevent or make illegal the
consummation of the Merger; (e) all material required consents and approvals of
governmental agencies or private persons or entities shall have been obtained;
(f) the shares of Noble Common Stock and $1.50 Noble Preferred Stock issuable
upon consummation of the Merger and the shares of Noble Common Stock issuable
upon conversion of the $1.50 Noble Preferred Stock or upon exercise of any
Assumed Options have been approved for listing on the NASDAQ National Market
System; and (g) Noble and Chiles shall be advised in writing on the Closing Date
by Arthur Andersen & Co. that, in accordance with generally accepted accounting
principles, the Merger should qualify for treatment as a "pooling of interests"
for accounting purposes.
 
     The obligation of Noble to consummate the Merger is subject to the
fulfillment at or prior to the Closing Date of certain additional conditions,
including (a) the accuracy of the representations and warranties of Chiles and
the compliance by Chiles with all covenants made by it under the Merger
Agreement; (b) that there has not been any material adverse change in the
business, operations or financial condition of Chiles and its subsidiaries from
the date of the Merger Agreement through the Closing Date; (c) that the fairness
opinion of Simmons has not been withdrawn; (d) that Chiles shall have received
certain agreements from its affiliates relating to resales of Noble Common Stock
to be received by such persons in the Merger; (e) that Noble shall have received
an opinion from Vinson & Elkins L.L.P., counsel to Chiles, with respect to
certain legal matters; (f) that the opinion received by Noble from Thompson &
Knight, A Professional Corporation with respect to certain tax aspects of the
Merger shall not have been withdrawn or modified in any material respect; (g)
that the Shareholder Voting Agreement dated April 23, 1990, as amended on May
24, 1991, among P.A.J.W., OMI, AWILCO Shipping and WILCO A/S has been terminated
or will terminate by its terms as of the Effective Time; and (h) that certain
documentation to permit the export of the drilling rigs of Chiles that have been
imported by Chiles and its Nigerian agent into Nigeria shall have been executed
by Chiles and such agent.
 
     The obligation of Chiles to effect the Merger is also subject to the
fulfillment at or prior to the Closing Date of certain additional conditions,
including (a) the accuracy of the representations and warranties of Noble and
the compliance by Noble with all covenants made by it under the Merger
Agreement; (b) the absence of any material adverse change in the business,
operations or financial condition of Noble from the date of the Merger Agreement
through the Closing Date; (c) that the fairness opinion of Salomon has not been
withdrawn; (d) that the Board of Directors of Noble has taken such action as may
be necessary to elect the persons designated by Chiles to the Noble Board of
Directors effective as of the Effective Time; (e) that Noble shall have received
certain agreements from its affiliates relating to resales of Noble Common
Stock; (f) that Chiles shall have received an opinion from Thompson & Knight, A
Professional Corporation, counsel to Noble, with respect to certain legal
matters; and (g) that the opinion received by Chiles from Vinson & Elkins L.L.P.
with respect to certain tax aspects of the Merger shall not have been withdrawn
or modified in any material respect.
 
TERMINATION
 
     General. The Merger Agreement may be terminated and the Merger and the
other transactions contemplated thereby may be abandoned, at any time prior to
the Effective Time, whether prior to or after approval by the stockholders of
Noble or the stockholders of Chiles, under the following circumstances: (a) by
the mutual consent of Noble and Chiles; (b) by either party if the Merger has
not been consummated by January 31, 1995; (c) by Noble if the fairness opinion
of Simmons has been withdrawn; (d) by Chiles if the fairness opinion of Salomon
has been withdrawn; (e) by either Noble or Chiles if a final, unappealable order
of a judicial or administrative authority of competent jurisdiction to restrain,
enjoin or otherwise prevent a consummation of the Merger Agreement or the
transactions contemplated thereby shall have been entered; (f) by either party
if the required approval of the stockholders of the other party is not received
in a vote duly taken at their respective stockholders' meetings; (g) by Noble if
(i) since the date of the Merger Agreement
 
                                       40
<PAGE>   53
 
there has been a material adverse change in the business, operations or
financial condition of Chiles and its subsidiaries, taken as a whole, or (ii)
there has been a material breach of any representation, warranty or covenant by
Chiles that is not remedied within five business days of notice of such breach;
(h) by Chiles if (i) since the date of the Merger Agreement there has been a
material adverse change in the business, operations or financial condition of
Noble and its subsidiaries, taken as a whole, or (ii) there has been a material
breach of any representation, warranty or covenant by Noble that is not remedied
within five business days of notice of such breach; or (i) by Noble if the Board
of Directors of Chiles exercises its right not to convene a meeting of its
stockholders pursuant to the provisions of the Merger Agreement described above
under "-- Solicitation of Third Party Offers."
 
     Termination Fee. In the event that either Noble or Chiles terminates the
Merger Agreement pursuant to clauses (a), (b), (d), (f), (g)(ii) or (i) of the
preceding paragraph and (i) the Merger Agreement has either not been submitted
to the stockholders of Chiles or the stockholders of Chiles have declined to
approve the Merger Agreement by the requisite vote, (ii) after the date of the
Merger Agreement but at or before the time the Merger Agreement is terminated
there shall have been a Chiles Acquisition Transaction proposed in writing to
Chiles and (iii) any Chiles Acquisition Transaction (whether the same or
different from the one referenced in clause (ii)) is consummated at any time
within one year after the date of the Merger Agreement, then Chiles will
promptly pay to Noble the sum of $6,000,000.
 
     Expense Reimbursement. If the Merger Agreement is terminated because of the
failure of the other party to secure the approval of its stockholders as
required under the Merger Agreement and certain conditions to Closing set forth
in the Merger Agreement have otherwise been satisfied, then the party whose
stockholders failed to make the required approval will pay to the other party an
amount equal to $1,000,000 as reimbursement for out-of-pocket fees and expenses
incurred in connection with the transactions contemplated by the Merger
Agreement (subject, in the case of Chiles, to offset against any amount payable
to Noble under the provisions described above under "-- Termination Fee").
 
                           INVESTMENT CONSIDERATIONS
 
     The following considerations should be evaluated by stockholders before
determining how to vote at the respective special meetings.
 
INTENSE COMPETITION; INDUSTRY CONDITIONS
 
     The offshore contract drilling industry is a highly competitive and
cyclical business. It is characterized by high capital costs and numerous
industry participants, none of which has a significant market share but certain
of which may have greater financial resources than Noble. Noble's operations are
materially dependent upon the levels of activity in offshore oil and natural gas
exploration, development and production. Such activity levels are affected both
by short-term and long-term trends in oil and natural gas prices. In recent
years, oil and natural gas prices and, therefore, the level of offshore drilling
and exploration activity, have been extremely volatile. Worldwide military,
political and economic events, including initiatives by the Organization of
Petroleum Exporting Countries, have contributed to, and are likely to continue
to contribute to, price volatility. As events during recent years have
exhibited, any prolonged reduction in oil and natural gas prices would depress
the level of offshore exploration and development activity and result in a
corresponding decline in the demand for Noble's services and therefore have a
material adverse effect on Noble's revenues and profitability. Noble can predict
neither the future level of demand for its drilling services nor the future
conditions in the offshore contract drilling industry.
 
LOSSES FROM OPERATIONS
 
     The historical financial data for Noble reflect net losses applicable to
common shares of $18,185,000, $10,918,000 and $8,751,000 for the years ended
December 31, 1992, 1991 and 1990, respectively. Noble had net income applicable
to common shares of $14,188,000 for the year ended December 31, 1993. Continued
profitability of Noble will be dependent upon the utilization of and rates for
its drilling rigs. There can be no assurance that the improved levels of
utilization and the higher dayrates that resulted in net income for the
 
                                       41
<PAGE>   54
 
year ended December 31, 1993 will continue. Utilization levels and dayrates
experienced during 1994 have been generally lower than those experienced in
1993.
 
SUBSTANTIAL INTERNATIONAL OPERATIONS
 
     A major portion of Noble's revenues has been attributable to international
operations. Revenues from international sources accounted for approximately 60
percent of Noble's operating revenues in 1993. Risks associated with Noble's
operations in international markets include risks of war and civil disturbances
or other risks that may limit or disrupt markets, expropriation,
nationalization, foreign exchange restrictions and currency fluctuations,
foreign taxation, changing political conditions and foreign and domestic
monetary policies. For example, recent political instability in West Africa has
resulted in reduced demand for drilling services in that region. Additionally,
the ability of Noble to compete in the international drilling market may be
adversely affected by foreign governmental regulations that favor or require the
awarding of drilling contracts to local contractors, or by regulations requiring
foreign contractors to employ citizens of, or purchase supplies from, a
particular jurisdiction. Furthermore, no predictions can be made as to what
foreign governmental regulations may be enacted in the future that could be
applicable to the contract drilling industry.
 
CONCENTRATION OF OPERATIONS IN CERTAIN MARKETS
 
     Currently, 20 of Noble's 31 mobile offshore drilling rigs are located in
the Gulf of Mexico and six are located off the coast of West Africa. Eleven of
Chiles' 13 drilling rigs currently are located in the Gulf of Mexico and two are
located off the coast of West Africa. Consequently, given the concentration of
such drilling rigs in those regions, a decrease in the demand for offshore
drilling rigs in the Gulf of Mexico, and to a lesser extent in West Africa,
could have a material adverse effect on the financial performance of Noble.
 
ABSENCE OF DIVIDENDS ON NOBLE COMMON STOCK
 
     Noble has not paid any cash dividends on the Noble Common Stock since
becoming a publicly held corporation in October 1985 and does not anticipate
paying dividends on the Noble Common Stock at any time in the foreseeable
future. The $2.25 Noble Preferred Stock has, and the $1.50 Noble Preferred Stock
will have, priority as to dividends over Noble Common Stock, and no dividend
(other than dividends payable solely in Noble Common Stock) may be declared,
paid or set apart for payment on the Noble Common Stock unless all accrued and
unpaid dividends on the $2.25 Noble Preferred Stock and the $1.50 Noble
Preferred Stock have been paid or declared and set apart for payment.
 
RESTRICTIONS ON FOREIGN OWNERSHIP
 
     The Restated Certificate of Incorporation of Noble contains limitations on
the percentage of outstanding Noble Common Stock and Noble preferred stock of
any series that can be owned by persons who are not United States citizens
within the meaning of certain U.S. statutes relating to ownership of U.S. flag
vessels. Applying the statutory requirements, the Restated Certificate of
Incorporation would currently prohibit more than 45 percent of the outstanding
Noble Common Stock and of all series of preferred stock of Noble combined from
being owned by non-U.S. citizens. As of June 30, 1994, approximately .01 percent
of the outstanding Noble Common Stock and none of the outstanding $2.25 Noble
Preferred Stock was held by record holders with registered addresses outside the
United States. The limitations imposed by Noble's Restated Certificate of
Incorporation may at times restrict the ability of Noble's stockholders to
transfer shares of their stock to non-U.S. citizens. See "Description of Noble
Capital Stock -- Foreign Ownership."
 
OPERATIONAL RISKS AND INSURANCE
 
     Noble's operations are subject to the many hazards inherent in the drilling
business, including blowouts, cratering, fires and collisions or groundings of
offshore equipment, which could cause substantial damage to the environment, and
damage or loss from adverse weather and seas. These hazards could cause personal
injury and loss of life, suspend drilling operations or seriously damage or
destroy the property and equipment
 
                                       42
<PAGE>   55
 
involved and, in addition to environmental damage, could cause substantial
damage to producing formations and surrounding areas. Although Noble maintains
insurance against many of these hazards, such insurance is subject to
substantial deductibles and provides for premium adjustments based on claims. It
also excludes certain matters from coverage, such as loss of earnings on certain
rigs. Also, while Noble generally obtains indemnification from its customers for
environmental damage with respect to offshore drilling, such indemnification is
generally only in excess of a specified amount, which usually ranges from
$100,000 to $250,000.
 
     In the case of the turnkey drilling operations of Triton, Triton maintains
insurance against pollution and environmental damage in amounts ranging from $5
million to $50 million depending on location, subject to self-insured retentions
of $100,000 to $500,000. Under turnkey drilling contracts, Triton generally
assumes the risk of pollution and environmental damage, but on occasion receives
indemnification from the customer for environmental and pollution liabilities in
excess of Triton's pollution insurance coverage. Further, Triton is not insured
against certain drilling risks that could result in delays or nonperformance of
a turnkey drilling contract. Triton typically secures indemnities for pollution
arising from certain acts of the drilling contractors that provide the rigs for
Triton's turnkey drilling operations.
 
     Notwithstanding the insurance and indemnity coverage provided to Noble, the
occurrence of a significant event not fully insured or indemnified against or
the failure of a customer to meet its indemnification obligations could
materially and adversely affect Noble's operations and financial condition.
Moreover, no assurance can be given that Noble will be able to maintain adequate
insurance in the future at rates it considers reasonable or that any particular
types of coverage will be available.
 
GOVERNMENTAL REGULATION AND ENVIRONMENTAL MATTERS
 
     Many aspects of Noble's operations are affected by domestic and foreign
political developments and are subject to numerous domestic and foreign
governmental regulations that may relate directly or indirectly to the contract
drilling industry. The regulations applicable to Noble's operations include
certain regulations controlling the discharge of materials into the environment,
requiring removal and cleanup under certain circumstances or otherwise relating
to the protection of the environment. Laws and regulations protecting the
environment have become more stringent in recent years, and may in certain
circumstances impose "strict liability," rendering a person liable for
environmental damage without regard to negligence or fault on the part of such
person. Such laws and regulations may expose Noble to liability for the conduct
of, or conditions caused by, others, or for acts of Noble which were in
compliance with all applicable laws at the time such acts were performed. The
application of these requirements or the adoption of new requirements could have
a material adverse effect on Noble. In addition, the modification of existing
laws or regulations or the adoption of new laws or regulations curtailing
exploratory or development drilling for oil and gas for economic, environmental
or other reasons could have a material adverse effect on Noble's operations by
limiting drilling opportunities.
 
     Noble's operations in the Gulf of Mexico are subject to the U.S. Oil
Pollution Act of 1990 (the "OPA") and the regulations promulgated pursuant
thereto. Noble generally seeks to obtain indemnity agreements whenever possible
from Noble's customers requiring such customers to hold Noble harmless from
liability for pollution that originates below the water surface (including,
where applicable, liability under the OPA) and maintains marine liability
insurance and contingent operators extra expense insurance, all of which affords
Noble limited protection. When obtained, such contractual indemnification
protection may not in all cases be supported by adequate insurance maintained by
the customer. There is no assurance that any such insurance or contractual
indemnity protection will be sufficient or effective under all circumstances.
 
LIMITATION ON USE OF NET OPERATING LOSS CARRYFORWARDS
 
     If a corporation undergoes an "ownership change" within the meaning of
Section 382 of the Code, the corporation's right to use its then-existing net
operating loss carryforwards ("NOLs") (and certain other tax attributes), for
both regular tax and alternative minimum tax purposes, during each future year
is limited to a percentage (currently approximately six percent) of the fair
market value of such corporation's stock
 
                                       43
<PAGE>   56
 
immediately before the ownership change (the "Section 382 Limitation"). In
general, there is an "ownership change" under Section 382 if over a three-year
period certain stockholders increase their percentage ownership of a corporation
(with NOLs) by more than 50 percentage points. To the extent that taxable income
exceeds the Section 382 Limitation in any year subsequent to the ownership
change, such excess income may not be offset by NOLs from years prior to the
ownership change. To the extent the amount of taxable income in any subsequent
year is less than the Section 382 Limitation for such year, the Section 382
Limitation for future years is correspondingly increased. There is generally no
restriction on the use of NOLs arising after the ownership change, although
Section 382 applies anew each time there in an ownership change.
 
     As of December 31, 1993, Noble had approximately $91,468,000 of NOLs, a
significant portion of which may be subject to a Section 382 Limitation
resulting from ownership changes in years prior to the year of the Merger. Noble
believes that another ownership change with respect to Noble may occur as a
result of the Merger. The resulting Section 382 Limitation may limit Noble's
ability to use its NOLs in future years, although the actual effect, if any, of
such limitation will depend on Noble's profitability in future years. Noble does
not believe that any Section 382 Limitation resulting from the Merger or from
any prior ownership changes will have a material adverse effect on Noble's
ability to utilize its NOLs.
 
     As of December 31, 1993, Chiles had approximately $69,600,000 of NOLs.
Chiles believes that an ownership change with respect to Chiles will occur as a
result of the Merger. The resulting Section 382 Limitation may limit Noble's
ability to use Chiles' NOLs in future years, although the actual effect, if any,
of such limitation will depend on Noble Sub's profitability in future years.
Chiles does not believe that any Section 382 Limitation resulting from the
Merger will have a material adverse effect on Noble's ability to utilize Chiles'
NOLs.
 
                   PROPOSAL TO ADOPT NOBLE CHARTER AMENDMENT
 
BACKGROUND AND REASONS
 
     As of May 31, 1994, there were issued and outstanding 48,390,873 shares of
Noble Common Stock, and an aggregate of 19,755,352 shares of Noble Common Stock
were reserved for issuance and issuable (i) pursuant to certain Noble employee
benefit plans, (ii) upon the exercise of outstanding employee or non-employee
director stock options or (iii) upon the conversion of the $2.25 Noble Preferred
Stock. In addition, an indeterminate number of shares of Noble Common Stock (of
up to at least 254,551 shares) were reserved for issuance pursuant to the Triton
Agreement.
 
     The authorized capital stock of Noble currently consists of 75,000,000
shares of Noble Common Stock and 15,000,000 shares of preferred stock.
Consequently, there are not a sufficient number of shares of Noble Common Stock
available to permit Noble to consummate the Merger. In order to permit Noble to
consummate the Merger and to provide Noble the flexibility to issue Noble Common
Stock in future transactions should the Board of Directors of Noble determine it
is appropriate, the Board is proposing that the Restated Certificate of
Incorporation of Noble be amended to increase the number of authorized shares of
Noble Common Stock by 125,000,000 shares (referred to herein as the Noble
Charter Amendment). If the Noble Charter Amendment is adopted, the additional
shares of Noble Common Stock would be available for future issuance at the
discretion of the Noble Board without further action by the stockholders of
Noble and, depending on the circumstances of any such issuance, could result in
dilution of existing stockholders' interests. There are no pending or proposed
transactions, financings or other uses currently contemplated by the Board of
Directors of Noble for the issuance of the additional shares of Noble Common
Stock other than as described in this Joint Proxy Statement/Prospectus with
respect to the Merger.
 
PROPOSED NOBLE CHARTER AMENDMENT
 
     The Board of Directors of Noble has declared it advisable and has adopted,
and recommends that the holders of Noble Common Stock adopt, the Noble Charter
Amendment to revise Article IV, Section 1 of
 
                                       44
<PAGE>   57
 
Noble's Restated Certificate of Incorporation by deleting such section in its
entirety and substituting therefor the following:
 
          Section 1. The total number of shares of all classes of stock which
     the Corporation shall have authority to issue is 215,000,000 consisting of
     (1) 15,000,000 shares of Preferred Stock, par value $1.00 per share
     ("Preferred Stock"), and (2) 200,000,000 shares of Common Stock, par value
     $.10 per share ("Common Stock").
 
RECOMMENDATION AND REQUIRED AFFIRMATIVE VOTE
 
     The affirmative vote of the holders of a majority of the shares of Noble
Common Stock outstanding and entitled to vote at the Noble Special Meeting is
required to adopt the Noble Charter Amendment. The Board of Directors of Noble
has declared the Noble Charter Amendment advisable and believes it is in the
best interests of Noble and its stockholders. Accordingly, the Board of
Directors of Noble unanimously recommends that its stockholders vote FOR the
Noble Charter Amendment. If the Noble Charter Amendment is not adopted, the
Merger cannot be consummated, regardless of whether the Merger Proposal is
adopted by the stockholders of Noble. Noble intends to effect the Noble Charter
Amendment, if adopted by stockholders, irrespective of whether the Merger
Proposal is approved.
 
                    PROPOSAL TO APPROVE NOBLE PLAN AMENDMENT
 
GENERAL
 
     The Noble Drilling Corporation 1991 Stock Option and Restricted Stock Plan
(the "Plan") was adopted by the Board of Directors of Noble in 1991 and approved
by the stockholders of Noble at the 1991 annual meeting of stockholders. At
meetings of the Noble Board of Directors in June and July 1994, the Board
adopted a proposal to amend the Plan to (i) increase from 1,900,000 to 5,200,000
the aggregate number of shares of Noble Common Stock available for issuance
under the Plan and (ii) make certain changes to the Plan to preserve for federal
income tax purposes the deductibility of compensation paid under the Plan in the
form of nonqualified stock options (collectively, the Noble Plan Amendment). The
proposal to amend the Plan is subject to the approval of the holders of Noble
Common Stock. The material features of the Plan as currently in effect are
described below.
 
     The number of options or shares of restricted stock that may be granted
under the Plan (as amended in accordance with the Noble Plan Amendment) to any
person entitled to participate in the Plan are not currently determinable.
 
     In January 1994, options were granted under the Plan to purchase an
aggregate of 578,000 shares of Noble Common Stock. All such options were granted
with an exercise price of $7.38, the last reported sale price of a share of
Noble Common Stock on the date of grant. The last sale price of the Noble Common
Stock reported on the NASDAQ National Market System on August   , 1994 was
$          per share.
 
REASONS AND PRINCIPAL EFFECTS OF THE PROPOSAL
 
     Increase in Shares of Noble Common Stock Issuable Under the Plan. As of
June 30, 1994, there were outstanding stock options covering 1,834,620 shares of
Noble Common Stock held by 214 persons and only 488,637 shares of Noble Common
Stock remained available for future awards under the Plan. The purpose of the
Noble Plan Amendment is to continue the Plan by increasing by 3,300,000 shares
the aggregate number of shares of Noble Common Stock that may be issued under
the Plan. This increase in the number of shares issuable under the Plan could be
particularly important if the Merger is consummated and the number of employees
who may become eligible to participate in the Plan is thereby increased. If the
Noble Plan Amendment is approved, the employees of Noble who are eligible to
participate in the Plan could receive more benefits under the Plan than they
could if the Noble Plan Amendment is not approved.
 
     Limitation on Number of Shares Covered by Plan Grants and Awards;
Administration by Outside Directors. Pursuant to recently enacted changes to the
Code, the amount of compensation payments to certain
 
                                       45
<PAGE>   58
 
highly compensated officers that employers may deduct from income for federal
income tax purposes has been limited to $1,000,000 per person per year.
Compensation recognized by employees in connection with the exercise of options
and stock appreciation rights ("SARs") granted under the Plan may, however, be
exempt from the $1,000,000 limitation if certain requirements are satisfied,
including the requirements that (i) the Plan state the maximum number of shares
for which options or SARs may be granted during a specified period to any
employee and (ii) the Plan be administered by a committee comprised solely of
two or more "outside" directors within the meaning of the regulations
promulgated under the Code.
 
     Currently, the Plan does not limit the total number of shares of Noble
Common Stock for which options may be granted, or which may be awarded as
restricted stock, to a person under the Plan. In addition, the Plan is
administered by a committee of "disinterested" directors within the meaning of
Rule 16b-3 under the Exchange Act who are not necessarily outside directors
within the meaning of the regulations promulgated under the Code. In order to
ensure that the deductibility of compensation recognized by employees in
connection with the exercise of options and SARs granted under the Plan, the
Board of Directors of Noble has proposed to amend the Plan to (i) limit to
1,500,000 the total number of shares of Noble Common Stock that may be made
subject to grants of options or SARs or awards of restricted stock under the
Plan to any one person during any five-year period, and (ii) provide for
administration of the Plan by a committee comprised solely of outside directors
who are also disinterested directors.
 
DESCRIPTION OF PLAN AS CURRENTLY IN EFFECT
 
     Under the Plan, shares of Noble Common Stock may be subject to grants of
options and SARs or awards of restricted stock to officers and other employees
of Noble and its affiliates. Options and any SARs that relate to such options
may be granted, and restricted stock may be awarded, until the maximum number of
shares issuable under the Plan has been exhausted or the Plan has been
terminated, except that no incentive option and any SARs that relate to such
option shall be granted after January 31, 2001. Options granted under the Plan
may be either incentive options (which satisfy the requirements of Section
422(b) of the Code or nonqualified options (which do not satisfy such
requirements), and may be with or without SARs. Shares of Noble Common Stock
covered by an option that expires or terminates prior to exercise and shares of
restricted stock returned to Noble are again available for grant of options and
awards of restricted stock. The option price may not be less than the greater of
the par value or 100 percent of the fair market value of the Noble Common Stock
at the time of grant, in the case of an incentive option, and may not be less
than the greater of the par value or 50 percent of the fair market value of the
Noble Common Stock at the time of grant, in the case of a nonqualified option.
 
     The Plan is administered by the compensation committee (the "Committee") of
the Board of Directors of Noble. The Committee must consist of two or more
directors of Noble, all of whom must be disinterested persons as defined in Rule
16b-3 under the Exchange Act. The Committee determines the grants of options and
awards of restricted stock, the terms and provisions of the respective
agreements covering such grants or awards and all other decisions concerning the
Plan. It is impracticable to estimate the total number of employees eligible to
participate in the Plan. The Plan provides that the determination of the
Committee is binding with respect to all questions of interpretation and
application of the Plan and of options granted or awards of restricted stock
made thereunder.
 
     The Committee may from time to time grant SARs in conjunction with all or
any portion of an option either at the time of the initial option grant or, with
respect to a nonqualified option, at any time after the initial option grant
while the nonqualified option is outstanding. SARs generally will be subject to
the same terms and conditions and exercisable to the same extent as stock
options, as described above. SARs entitle an optionee to receive without payment
to Noble (except for applicable withholding taxes) the excess of the aggregate
fair market value per share with respect to which the SAR is then being
exercised (determined as of the date of such exercise) over the aggregate
purchase price of such shares as provided in the related option.
 
     Options will be exercisable at such time or times not more than 10 years
from the date of grant as may be provided by their terms. The Committee may,
however, accelerate the time at which an option is exercisable without regard to
its terms. Generally, all rights to exercise an option will terminate within
three months after
 
                                       46
<PAGE>   59
 
the date the optionee ceases to be an employee of Noble or an affiliate of Noble
for any reason other than death or becoming disabled (as defined). In the event
of an optionee's death or his becoming disabled, the option will terminate 12
months thereafter, or, if earlier, at the expiration of the option period. Any
optionee may be required to remain in the employment of Noble or an affiliate of
Noble for a stated period of time before the option may be exercised. If the
employment of the optionee is terminated on account of fraud, dishonesty or
other acts detrimental to the interests of Noble or one or more of its
affiliates, the option shall thereafter be null and void for all purposes.
 
     No option or any SARs that relate to such option are transferable except by
will or the laws of descent and distribution or pursuant to a qualified domestic
relations order; and during the lifetime of the optionee, the option and any
SARs that relate to such option may be exercised only by the optionee or his
guardian or legal representative. The exercise price of options may be paid in
cash, by certified check or cashier's check or, with the consent of the
Committee, by delivery of shares of Noble Common Stock, including actual or
deemed multiple exchanges of shares. In addition, the Committee is authorized by
the Plan to selectively approve arrangements with a brokerage firm under which
it would, on behalf of an optionee, make payment in full to Noble of the option
price for the shares then being purchased, and Noble, pursuant to an irrevocable
notice in writing from the optionee, would deliver the certificate for the
appropriate number of shares to such brokerage firm. Noble may satisfy its tax
withholding obligations by retaining shares of the Noble Common Stock that would
otherwise be issuable on exercise by an optionee.
 
     The Plan contains antidilution provisions applicable in the event of
increase or decrease in the number of outstanding shares of Noble, effected
without receipt of consideration therefor by Noble, through a stock dividend or
any recapitalization or merger or otherwise in which Noble is the surviving
corporation, resulting in a stock split-up, combination or exchange of shares of
Noble, in which event appropriate adjustments will be made in the maximum number
of shares subject to the Plan and the number of shares and option prices under
then outstanding options.
 
     The Noble Board of Directors may at any time amend, suspend or terminate
the Plan except that it may not, without the approval of stockholders, (i)
increase the maximum number of shares subject thereto, or (ii) reduce the option
price for shares covered by options granted under the Plan below the price
currently specified therein.
 
     The Plan also provides that restricted stock may be awarded by the
Committee to such eligible recipients as it may determine from time to time. The
eligible recipients are those individuals who are eligible for option grants.
Restricted stock is Noble Common Stock that may not be sold, assigned,
transferred, discounted, exchanged, pledged or otherwise encumbered or disposed
of until the terms and conditions set by the Committee, which terms and
conditions may include, among other things, the achievement of specific goals,
have been satisfied (the "Restricted Period"). During the Restricted Period,
unless specifically provided otherwise in accordance with the terms of the Plan,
the recipient of restricted stock would be the record owner of such shares and
have all the rights of a stockholder with respect to such shares, including the
right to vote and the right to receive dividends or other distributions made or
paid with respect to such shares.
 
     The Plan provides that the Committee has the authority to cancel all or any
portion of any outstanding restrictions prior to the expiration of the
Restricted Period with respect to any or all of the shares of restricted stock
awarded to an individual on such terms and conditions as the Committee may deem
appropriate. If during the Restricted Period an individual's continuous
employment terminates for any reason, any restricted stock remaining subject to
restrictions will be forfeited by the individual and transferred at no cost to
Noble; provided, however, that as noted above, the Committee has the authority
to cancel any or all outstanding restrictions prior to the end of the Restricted
Period, including the cancellation of restrictions in connection with certain
types of termination of employment.
 
UNITED STATES FEDERAL INCOME TAX CONSEQUENCES
 
     Generally, an optionee will not recognize income for federal income tax
purposes upon the grant or the exercise of an incentive option, and any gain on
the subsequent disposition of the option stock is treated as a capital gain
provided the option stock is held for the required holding period, which is two
years from the date
 
                                       47
<PAGE>   60
 
of grant of the option and one year from the transfer of the shares to the
optionee. Noble will not be entitled to any federal income tax deduction upon
the exercise of an incentive option.
 
     If an optionee uses already owned shares of Noble Common Stock to pay the
exercise price for shares under an incentive option, the resulting tax
consequences will depend upon whether such already owned shares of Noble Common
Stock are "statutory option stock," and, if so, whether such statutory option
stock has been held by the optionee for the applicable holding period. If such
stock is statutory option stock with respect to which the applicable holding
period has been satisfied, no income will be recognized by the optionee upon the
transfer of such stock in payment of the exercise price of an incentive option.
If such stock is not statutory option stock, no income will be recognized by the
optionee upon the transfer of such stock unless such stock is not substantially
vested within the meaning of the Code (in which event it appears that the
optionee will recognize ordinary income upon the transfer equal to the amount by
which the fair market value of the transferred shares exceeds their basis). If
the stock used to pay the exercise price of an incentive option is statutory
option stock with respect to which the applicable holding period has not been
satisfied, the transfer of such stock will be a disqualifying disposition which
will result in the recognition of ordinary income by the optionee in an amount
equal to the excess of the fair market value of the statutory option stock at
the time the option covering such stock was exercised over the option price of
such stock.
 
     No income will be recognized by an optionee for federal income tax purposes
upon the grant of a nonqualified option. Except as described below in the case
of an "insider" subject to Section 16(b) of the Exchange Act who exercises an
option less than six months from the date of grant, upon exercise of a
nonqualified option, the optionee will recognize ordinary income in an amount
equal to the excess of the fair market value of the option stock on the date of
exercise over the option price of such stock. In the absence of an election
pursuant to Section 83(b) of the Code, an "insider" subject to Section 16(b) of
the Exchange Act who exercises a nonqualified option less than six months from
the date the option was granted will recognize income on the date six months
after the date of grant. An optionee subject to Section 16(b) of the Exchange
Act can avoid such deferral by making an election, pursuant to Section 83(b) of
the Code. Executive officers, directors and 10 percent stockholders of Noble
will generally be deemed to be "insiders" for purposes of Section 16(b) of the
Exchange Act.
 
     Income recognized upon the exercise of nonqualified options will be
considered compensation subject to withholding at the time such income is
recognized, and therefore, Noble or an affiliate must make the necessary
arrangements with the optionee to ensure that the amount of the tax required to
be withheld is available for payment. Nonqualified options are designed to
ensure that Noble will be entitled to a deduction equal to the amount of
ordinary income recognized by the optionee at the time of such recognition by
the optionee.
 
     If an optionee uses already owned shares of Noble Common Stock to pay the
exercise price for shares under a nonqualified option, the number of shares
received pursuant to the option which is equal to the number of shares delivered
in payment of the exercise price will be considered received in a nontaxable
exchange, and the fair market value of the remaining shares received by the
optionee upon such exercise will be taxable to the optionee as ordinary income.
 
     The exercise of an SAR will result in the recognition of ordinary income by
the optionee on the date of exercise in an amount equal to the amount of cash
and the fair market value on that date of any shares acquired pursuant to the
exercise. Noble will be allowed a federal income tax deduction equal to the
amount of ordinary income recognized by the optionee at the time of such
recognition by the optionee.
 
     The recipient of restricted stock will recognize income for federal income
tax purposes on restricted stock received by him at the first time the stock
becomes freely transferable or not subject to a substantial risk of forfeiture,
whichever occurs earlier. At such time, he will include in gross income the
excess of the then fair market value of the restricted stock (determined without
regard to any restriction other than a restriction which by its terms will never
lapse) over the amount, if any, paid for such stock. However, a recipient of
restricted stock can elect to include the restricted stock in his gross income
for the taxable year in which he first receives such stock by making an election
under Section 83(b) of the Code. Noble will be entitled to a
 
                                       48
<PAGE>   61
 
federal income tax deduction in the tax year in which the restricted stock
becomes taxable to the recipient in an amount equal to the amount the recipient
is required to include in income with respect to such shares.
 
RECOMMENDATION AND REQUIRED AFFIRMATIVE VOTE
 
     The affirmative vote of the holders of record of a majority of the
outstanding shares of Noble Common Stock present in person or by proxy and
entitled to vote thereon at the Noble Special Meeting is required in order to
approve the Noble Plan Amendment. The Board of Directors of Noble unanimously
recommends that its stockholders vote FOR the approval of the Noble Plan
Amendment. If the Noble Plan Amendment is approved by the Noble Stockholders, it
will be effected, regardless of whether the Merger Proposal is approved or the
Noble Plan Amendment is adopted.
 
                                       49
<PAGE>   62
 
               UNAUDITED PRO FORMA COMBINED FINANCIAL STATEMENTS
 
     The following unaudited pro forma combined financial statements give effect
to the consummation of (i) the Merger only and (ii) both the Merger and the
Triton Acquisition. The Merger is accounted for as a "pooling of interests" as
if the Merger had been in effect for all periods presented while the Triton
Acquisition is accounted for as a "purchase" as if the Triton Acquisition had
occurred on January 1, 1993. The following unaudited pro forma combined
financial statements do not purport to be indicative of the results that would
actually have been obtained if the combinations had been in effect as of the
dates indicated or that may be obtained in the future. The statements are based
upon the consolidated financial statements of Noble, Triton and Chiles that have
been incorporated by reference into this Joint Proxy Statement/Prospectus and
should be read in conjunction with those financial statements and the related
notes.
 
     In developing the pro forma financial statements referred to above, the
respective accounting policies and practices of Noble and Chiles were reviewed
in order to determine the need for inclusion of conforming pooling adjustments.
Certain differences exist between Noble and Chiles in the application of
accounting policy for depreciation of fixed assets. The effects of these
differences have been ascertained and, due to their immaterial impact on the
financial statements of the combined companies, have not been accounted for as
conforming adjustments in the financial statements as presented. Certain
reclassifications, however, have been made to Chiles' historical amounts for
consistency with the Noble presentation. The purchase adjustments for the Triton
Acquisition are based on estimates and are subject to change based on further
refinement.
 
                                       50
<PAGE>   63
 
                            NOBLE, CHILES AND TRITON
 
                   UNAUDITED PRO FORMA COMBINED BALANCE SHEET
                                 MARCH 31, 1994
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                                                             PRO
                                                                         PURCHASE           FORMA
                                     NOBLE       CHILES       TRITON     ADJUSTMENTS       COMBINED
                                    --------    --------      -------    --------          --------
<S>                                 <C>         <C>           <C>        <C>               <C>
              ASSETS
CURRENT ASSETS
  Cash and cash equivalents........ $  9,674    $ 38,253      $17,685    $ (4,085)(A)      $ 61,527
  Restricted cash..................    1,789                                                  1,789
  Investment in marketable
     securities....................   34,873      31,251                                     66,124
  Accounts receivable..............   41,748      15,905       22,666                        80,319
  Other current assets.............   37,937       1,826       16,527                        56,290
                                    --------    --------      -------    --------          --------
          Total current assets.....  126,021      87,235       56,878      (4,085)          266,049
                                    --------    --------      -------    --------          --------
PROPERTY AND EQUIPMENT
  Drilling equipment and
     facilities....................  621,689     150,455        4,846      (3,403)(B)       773,587
  Other............................   13,995       1,954        4,216      (1,502)(B)        18,663
                                    --------    --------      -------    --------          --------
                                     635,684     152,409        9,062      (4,905)          792,250
  Accumulated depreciation......... (268,311)    (40,286)      (4,905)      4,905(B)       (308,597)
                                    --------    --------      -------    --------          --------
                                     367,373     112,123        4,157                       483,653
                                    --------    --------      -------    --------          --------
OTHER ASSETS.......................   13,483                                  336(C)         13,819
                                    --------    --------      -------    --------          --------
                                    $506,877    $199,358      $61,035    $ (3,749)         $763,521
                                    ========    ========      =======    ========          ========
          LIABILITIES AND
       SHAREHOLDERS' EQUITY
CURRENT LIABILITIES
  Short-term debt.................. $           $             $ 1,566    $  4,000(A)       $  5,566
  Current installments of long-term
     debt..........................      546                                                    546
  Accounts payable.................    7,569       4,881       13,355                        25,805
  Interest payable.................    5,612                                                  5,612
  Other current liabilities........   33,305       4,217       27,804                        65,326
                                    --------    --------      -------    --------          --------
          Total current
            liabilities............   47,032       9,098       42,725       4,000           102,855
LONG-TERM DEBT.....................  127,138                                                127,138
OTHER LIABILITIES..................    1,108         293                                      1,401
MINORITY INTEREST..................      119                    5,392                         5,511
                                    --------    --------      -------    --------          --------
                                     175,397       9,391       48,117       4,000           236,905
                                    --------    --------      -------    --------          --------
SHAREHOLDERS' EQUITY
  Preferred stock..................    2,990       4,025                                      7,015
  Common stock.....................    4,784       2,857(E)        12          63(A)(D)       7,716
  Capital in excess of par value...  333,710     249,498(E)                 5,094(A)        588,302
  Cumulative translation
     adjustment....................   (2,641)                                                (2,641)
  Retained earnings................   (5,613)    (66,413)      17,212     (17,212)(D)       (72,026)
  Treasury stock, at cost..........   (1,750)                  (4,306)      4,306(D)         (1,750)
                                    --------    --------      -------    --------          --------
                                     331,480     189,967       12,918      (7,749)          526,616
                                    --------    --------      -------    --------          --------
                                    $506,877    $199,358      $61,035    $ (3,749)         $763,521
                                    ========    ========      =======    ========          ========
</TABLE>
 
- ---------------
 
(A) To record the purchase by Noble of all the outstanding shares of common
    stock of Triton.
 
(B) To record the effect of Noble accounting for the fixed assets of Triton at
    fair market value.
 
(C) To record goodwill of $336,000, which represents the excess of the purchase
    price over net assets acquired in the Triton Acquisition.
 
(D) To eliminate Triton's equity pursuant to the Triton Agreement.
 
(E) Reflects the change in par value for the conversion of Chiles Common Stock
    into Noble Common Stock.
 
                                       51
<PAGE>   64
 
                            NOBLE, CHILES AND TRITON
 
              UNAUDITED PRO FORMA COMBINED STATEMENT OF OPERATIONS
                     FOR THREE MONTHS ENDED MARCH 31, 1994
                    (IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)
 
<TABLE>
<CAPTION>
                                                                                             PRO
                                                                          PURCHASE          FORMA
                                         NOBLE     CHILES      TRITON    ADJUSTMENTS      COMBINED
                                        -------    ------      ------    -----------      --------
<S>                                     <C>        <C>         <C>        <C>              <C>
OPERATING REVENUES
  Contract drilling services.........   $57,865    $19,673     $          $                $ 77,538
  Turnkey drilling services..........                           22,458                       22,458
  Engineering and consulting
     services........................       309                  1,536                        1,845
  Other revenue......................     1,074                  2,194        (53)(A)         3,215
                                        -------    -------     -------    -------          --------
                                         59,248     19,673      26,188        (53)          105,056
                                        -------    -------     -------    -------          --------
OPERATING COSTS AND EXPENSES
  Contract drilling operations.......    38,001     11,719                                   49,720
  Turnkey drilling operations........                           18,989                       18,989
  Engineering and consulting
     operations......................       258                    756                        1,014
  Other expense......................       601                  1,376         (2)(A)         1,975
  Depreciation and amortization......     7,161      2,337         236          9(B)          9,743
  Selling, general and
     administrative..................     6,324      2,195       4,476     (1,070)(C)        11,925
  Minority interest..................       (37)                   493                          456
                                        -------    -------     -------    -------          --------
                                         52,308     16,251      26,326     (1,063)           93,822
                                        -------    -------     -------    -------          --------
OPERATING INCOME (LOSS)..............     6,940      3,422        (138)     1,010            11,234
OTHER INCOME (EXPENSE)
  Interest expense...................    (3,000)                                             (3,000)
  Interest income....................       587        573         123                        1,283
  Other, net.........................     1,143                 (2,361)     2,271(A)(D)       1,053
                                        -------    -------     -------    -------          --------
INCOME (LOSS) FROM CONTINUING
  OPERATIONS BEFORE INCOME TAXES.....     5,670      3,995      (2,376)     3,281            10,570
INCOME TAX PROVISION.................    (1,203)      (341)       (115)      (696)(E)        (2,355)
                                        -------    -------     -------    -------          --------
INCOME (LOSS) FROM CONTINUING
  OPERATIONS.........................     4,467      3,654      (2,491)     2,585             8,215
PREFERRED DIVIDENDS..................    (1,682)    (1,509)                                  (3,191)
                                        -------    -------     -------    -------          --------
INCOME (LOSS) FROM CONTINUING
  OPERATIONS APPLICABLE TO COMMON
  SHARES.............................   $ 2,785    $ 2,145     $(2,491)   $ 2,585          $  5,024
                                        =======    =======     =======    =======          ========
INCOME (LOSS) FROM CONTINUING
  OPERATIONS PER COMMON SHARE........   $  0.06    $  0.08(F)                              $   0.06
                                        =======    =======                                 ========
PRO FORMA WEIGHTED AVERAGE COMMON
  SHARES OUTSTANDING.................    48,355     28,573(F)                 752            77,680
</TABLE>
 
- ---------------
 
(A) To reclassify the operating results of Triton's oil and gas activities, as
    these activities are not an ongoing business line of Noble.
 
(B) To record amortization of $9,000 for goodwill associated with the Triton
    Acquisition.
 
(C) To eliminate a nonrecurring stock options buyout effected by Triton in March
    1994 in connection with the Triton Acquisition.
 
(D) To eliminate the write-off of $2,220,000 of notes receivable from a
    partnership that was not part of the Triton Acquisition.
 
(E) To record the incremental tax effect of the Triton Acquisition adjustments.
 
(F) Reflects the conversion of each share of Chiles Common Stock into 0.75 of a
    share of Noble Common Stock.
 
                                       52
<PAGE>   65
 
                            NOBLE, CHILES AND TRITON
 
                   UNAUDITED PRO FORMA COMBINED BALANCE SHEET
                               DECEMBER 31, 1993
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                                                PURCHASE           PRO FORMA
                                             NOBLE       CHILES       TRITON    ADJUSTMENTS        COMBINED
                                           ---------    --------      -------   --------           ---------
<S>                                        <C>          <C>           <C>       <C>                <C>
                 ASSETS
CURRENT ASSETS
  Cash and cash equivalents.............   $   4,896    $ 64,281      $15,030   $ (4,085)(A)       $  80,122
  Restricted cash.......................       1,793                                                   1,793
  Investment in marketable securities...      37,387       2,064                                      39,451
  Accounts receivable...................      40,293      15,401       47,207                        102,901
  Other current assets..................      32,329       3,288        5,350                         40,967
                                           ---------    --------      -------   --------           ---------
          Total current assets..........     116,698      85,034       67,587     (4,085)            265,234
                                           ---------    --------      -------   --------           ---------
PROPERTY AND EQUIPMENT
  Drilling equipment and facilities.....     618,021     147,786        4,738     (3,237)(B)         767,308
  Other.................................      13,836       1,965        3,133     (2,380)(B)          16,554
                                           ---------    --------      -------   --------           ---------
                                             631,857     149,751        7,871     (5,617)            783,862
  Accumulated depreciation..............    (261,630)    (37,949)      (5,352)     5,352(B)         (299,579)
                                           ---------    --------      -------   --------           ---------
                                             370,227     111,802        2,519       (265)            484,283
                                           ---------    --------      -------   --------           ---------
OTHER ASSETS............................      12,792                    2,065     (1,638)(C)          13,219
                                           ---------    --------      -------   --------           ---------
                                           $ 499,717    $196,836      $72,171   $ (5,988)          $ 762,736
                                           =========    ========      =======   ========           =========
            LIABILITIES AND
          SHAREHOLDERS' EQUITY
CURRENT LIABILITIES
  Short-term debt.......................   $            $             $ 1,807   $  4,000(A)        $   5,807
  Current installments of long-term
     debt...............................         546                                                     546
  Accounts payable......................       9,110       4,549       33,309                         46,968
  Interest payable......................       3,548                                                   3,548
  Other current liabilities.............      29,085       4,359       14,999                         48,443
                                           ---------    --------      -------   --------           ---------
          Total current liabilities.....      42,289       8,908       50,115      4,000             105,312
LONG-TERM DEBT..........................     127,144                                                 127,144
OTHER LIABILITIES.......................       1,175         111                                       1,286
MINORITY INTEREST.......................         156                    6,899                          7,055
                                           ---------    --------      -------   --------           ---------
                                             170,764       9,019       57,014      4,000             240,797
                                           ---------    --------      -------   --------           ---------
SHAREHOLDERS' EQUITY
  Preferred stock.......................       2,990       4,025                                       7,015
  Common stock..........................       4,780       2,857(E)        12         63(A)(D)         7,712
  Capital in excess of par value........     333,617     249,493(E)                5,094(A)          588,204
  Cumulative translation adjustment.....      (2,286)                                                 (2,286)
  Retained earnings.....................      (8,398)    (68,558)      19,451    (19,451)(D)         (76,956)
  Treasury stock, at cost...............      (1,750)                  (4,306)     4,306(D)           (1,750)
                                           ---------    --------      -------   --------           ---------
                                             328,953     187,817       15,157     (9,988)            521,939
                                           ---------    --------      -------   --------           ---------
                                           $ 499,717    $196,836      $72,171   $ (5,988)          $ 762,736
                                           =========    ========      =======   ========           =========
</TABLE>
 
- ---------------
 
(A) To record the purchase by Noble of all the outstanding shares of common
    stock of Triton.
 
(B) To record the effect of Noble accounting for the fixed assets of Triton at
    fair market value.
 
(C) To record goodwill of $336,000, which represents the excess of the purchase
    price over net assets acquired and to eliminate other assets of $1,974,000
    that were not included in the Triton Acquisition which primarily consists
    of an investment of $1,293,000 in a partnership, $198,000 receivable from a
    stockholder and $574,000 of deferred income taxes.
 
(D) To eliminate Triton's equity pursuant to the Triton Agreement.
 
(E) Reflects the change in par value for the conversion of Chiles Common Stock
    into Noble Common Stock.
 
                                       53
<PAGE>   66
 
                            NOBLE, CHILES AND TRITON
 
              UNAUDITED PRO FORMA COMBINED STATEMENT OF OPERATIONS
                               DECEMBER 31, 1993
                    (IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)
 
<TABLE>
<CAPTION>
                                                                                PURCHASE ADJUSTMENTS           PRO
                                                                              ------------------------        FORMA
                                             NOBLE     CHILES       TRITON    TRITON           WESTERN(F)    COMBINED
                                            --------   -------     --------   ------           ----------    --------
<S>                                         <C>        <C>         <C>        <C>              <C>           <C>
OPERATING REVENUES
  Contract drilling services.............   $188,206   $69,589     $          $                $40,281       $298,076
  Turnkey drilling services..............                           110,003                                   110,003
  Engineering and consulting services....      2,292                  7,812                                    10,104
  Other revenue..........................      4,444                  6,019     (362)(A)                       10,101
                                            --------   -------     --------   ------           -------       --------
                                             194,942    69,589      123,834     (362)           40,281        428,284
                                            --------   -------     --------   ------           -------       --------
OPERATING COSTS AND EXPENSES
  Contract drilling operations...........    123,817    50,048                                  28,000        201,865
  Turnkey drilling operations............                            89,456                                    89,456
  Engineering and consulting
     operations..........................      2,083                  3,518                                     5,601
  Other expense..........................      2,736                  9,195      (59)(A)                       11,872
  Depreciation and amortization..........     20,472     8,414        1,170       34(B)          7,709         37,799
  Selling, general and administrative....     22,405     5,879       12,163                      1,168         41,615
  Minority interest......................       (232)                 4,767                                     4,535
                                            --------   -------     --------   ------           -------       --------
                                             171,281    64,341      120,269      (25)           36,877        392,743
                                            --------   -------     --------   ------           -------       --------
OPERATING INCOME (LOSS)..................     23,661     5,248        3,565     (337)            3,404         35,541
OTHER INCOME (EXPENSE)
  Interest expense.......................     (5,406)   (2,632)        (336)                    (7,604)(G)    (15,978)
  Interest income........................      1,628       869          293                                     2,790
  Other, net.............................      1,737      (690)         206      397(A)(C)                      1,650
                                            --------   -------     --------   ------           -------       --------
INCOME (LOSS) FROM CONTINUING OPERATIONS
  BEFORE INCOME TAXES....................     21,620     2,795        3,728       60            (4,200)        24,003
INCOME TAX PROVISION.....................     (2,474)     (859)      (2,222)      (7)(D)        (1,249)        (6,811)
                                            --------   -------     --------   ------           -------       --------
INCOME (LOSS) FROM CONTINUING OPERATIONS
  APPLICABLE TO COMMON SHARES............     19,146     1,936        1,506       53            (5,449)        17,192
PREFERRED DIVIDENDS......................     (6,728)   (1,208)                                                (7,936)
                                            --------   -------     --------   ------           -------       --------
INCOME (LOSS) FROM CONTINUING
  OPERATIONS.............................   $ 12,418   $   728     $  1,506   $   53           $(5,449)      $  9,256
                                            ========   =======     ========   ======           =======       ========
INCOME (LOSS) FROM CONTINUING OPERATIONS
  PER COMMON SHARE.......................   $   0.32   $  0.03(E)                                            $   0.12
                                            ========   =======                                               ========
PRO FORMA WEIGHTED AVERAGE COMMON SHARES
  OUTSTANDING............................     38,366    28,557(E)                752             9,235(H)      76,910
</TABLE>
 
- ---------------
 
(A) To reclassify the operating results of Triton's oil and gas activities, as
    these activities are not an ongoing business line of Noble.
 
(B) To record amortization of $34,000 for goodwill associated with the Triton
    Acquisition.
 
(C) To eliminate the net loss of $94,000 from an unconsolidated partnership that
    was not part of the Triton Acquisition.
 
(D) To record the incremental tax effect of the Triton Acquisition adjustments.
 
(E) Reflects the conversion of each share of Chiles Common Stock into 0.75 of a
    share of Noble Common Stock.
 
(F) Adjustments to include the effects of the Western Acquisition as if it
    occurred on January 1, 1993.
 
(G) Includes additional interest expense related to the Noble Senior Notes
    issued to finance a portion of the Western Acquisition.
 
(H) To record incremental weighted average shares outstanding related to the
    1993 Noble Common Stock offering used to finance the remaining portion of
    the Western Acquisition.
 
                                       54
<PAGE>   67
 
                                NOBLE AND CHILES
 
                  UNAUDITED PRO FORMA COMBINED BALANCE SHEETS
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                                                     DECEMBER
                                                                     MARCH 31,          31,
                                                                       1994            1993
                                                                     ---------       ---------
<S>                                                                  <C>             <C>
                              ASSETS
CURRENT ASSETS
  Cash and cash equivalents.......................................   $  47,927       $  69,177
  Restricted cash.................................................       1,789           1,793
  Investment in marketable securities.............................      66,124          39,451
  Accounts receivable.............................................      57,653          55,694
  Other current assets............................................      39,763          35,617
                                                                     ---------       ---------
          Total current assets....................................     213,256         201,732
                                                                     ---------       ---------
PROPERTY AND EQUIPMENT
  Drilling equipment and facilities...............................     772,144         767,772
  Other...........................................................      15,949          13,836
                                                                     ---------       ---------
                                                                       788,093         781,608
  Accumulated depreciation........................................    (308,597)       (299,579)
                                                                     ---------       ---------
                                                                       479,496         482,029
                                                                     ---------       ---------
OTHER ASSETS......................................................      13,483          12,792
                                                                     ---------       ---------
                                                                     $ 706,235       $ 696,553
                                                                     =========       =========
               LIABILITIES AND SHAREHOLDERS' EQUITY
CURRENT LIABILITIES
  Short-term debt.................................................   $               $
  Current installments of long-term debt..........................         546             546
  Accounts payable................................................      12,450          13,659
  Interest payable................................................       5,612           3,548
  Other current liabilities.......................................      37,522          33,444
                                                                     ---------       ---------
          Total current liabilities...............................      56,130          51,197
LONG-TERM DEBT....................................................     127,138         127,144
OTHER LIABILITIES.................................................       1,401           1,286
MINORITY INTEREST.................................................         119             156
                                                                     ---------       ---------
                                                                       184,788         179,783
                                                                     ---------       ---------
SHAREHOLDERS' EQUITY
  Preferred stock.................................................       7,015           7,015
  Common stock(A).................................................       7,641           7,637
  Capital in excess of par value(A)...............................     583,208         583,110
  Cumulative translation adjustment...............................      (2,641)         (2,286)
  Retained earnings...............................................     (72,026)        (76,956)
  Treasury stock, at cost.........................................      (1,750)         (1,750)
                                                                     ---------       ---------
                                                                       521,447         516,770
                                                                     ---------       ---------
                                                                     $ 706,235       $ 696,553
                                                                     =========       =========
</TABLE>
 
- ---------------
 
(A) Reflects the change in par value for the conversion of Chiles Common Stock
    into Noble Common Stock.
 
                                       55
<PAGE>   68
 
                                NOBLE AND CHILES
 
             UNAUDITED PRO FORMA COMBINED STATEMENTS OF OPERATIONS
                    (IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)
 
<TABLE>
<CAPTION>
                                             THREE MONTHS ENDED
                                                 MARCH 31,             YEAR ENDED DECEMBER 31,
                                             ------------------    --------------------------------
                                              1994       1993        1993        1992        1991
                                             -------    -------    --------    --------    --------
<S>                                          <C>        <C>        <C>         <C>         <C>
OPERATING REVENUES
  Contract drilling services..............   $77,538    $63,120    $257,795    $175,610    $217,065
  Turnkey drilling services...............
  Engineering and consulting services.....       309        869       2,292       3,263       8,286
  Other revenue...........................     1,074      1,334       4,444       5,293       4,800
                                             -------    -------    --------    --------    --------
                                              78,921     65,323     264,531     184,166     230,151
                                             -------    -------    --------    --------    --------
OPERATING COSTS AND EXPENSES
  Contract drilling operations............    49,720     47,511     173,865     128,364     169,322
  Turnkey drilling operations.............
  Engineering and consulting operations...       258        910       2,083       3,559       7,732
  Other expense...........................       601        678       2,736       3,329       2,436
  Depreciation and amortization...........     9,498      6,630      28,886      27,248      30,052
  Selling, general and administrative.....     8,519      7,319      28,284      30,716      32,684
  Minority interest.......................       (37)        17        (232)         89          78
  Restructuring charges and rig write
     downs................................                                       21,120      11,134
                                             -------    -------    --------    --------    --------
                                              68,559     63,065     235,622     214,425     253,438
                                             -------    -------    --------    --------    --------
OPERATING INCOME (LOSS)...................    10,362      2,258      28,909     (30,259)    (23,287)
OTHER INCOME (EXPENSE)
  Interest expense........................    (3,000)    (1,819)     (8,038)    (13,274)    (20,411)
  Interest income.........................     1,160        556       2,497       3,276       2,155
  Other, net..............................     1,143       (234)      1,047       3,675       4,786
                                             -------    -------    --------    --------    --------
INCOME (LOSS) FROM CONTINUING OPERATIONS
  BEFORE INCOME TAXES.....................     9,665        761      24,415     (36,582)    (36,757)
INCOME TAX PROVISION......................    (1,544)    (1,094)     (3,333)     (3,396)     (2,417)
                                             -------    -------    --------    --------    --------
INCOME (LOSS) FROM CONTINUING
  OPERATIONS..............................     8,121       (333)     21,082     (39,978)    (39,174)
PREFERRED DIVIDENDS.......................    (3,191)    (1,682)     (7,936)     (6,728)       (721)
                                             -------    -------    --------    --------    --------
INCOME (LOSS) FROM CONTINUING OPERATIONS
  APPLICABLE TO COMMON SHARES.............   $ 4,930    $(2,015)   $ 13,146    $(46,706)   $(39,895)
                                             =======    =======    ========    ========    ========
INCOME (LOSS) FROM CONTINUING OPERATIONS
  PER COMMON SHARE(A).....................   $  0.06    $ (0.03)   $   0.20    $  (0.98)   $  (0.88)
                                             =======    =======    ========    ========    ========
PRO FORMA WEIGHTED AVERAGE COMMON SHARES
  OUTSTANDING(A)..........................    76,928     63,252      66,923      47,762      45,554
</TABLE>
 
- ---------------
 
(A) Reflects the conversion of each share of Chiles Common Stock into 0.75 of a
    share of Noble Common Stock.
 
                                       56
<PAGE>   69
 
                       DESCRIPTION OF NOBLE CAPITAL STOCK
 
     Noble has 90,000,000 authorized shares of stock, consisting of (i)
75,000,000 shares of Noble Common Stock and (ii) 15,000,000 shares of preferred
stock having a par value of $1.00 per share. As of             , 1994, there
were 48,390,873 shares of Noble Common Stock outstanding. There is one series of
preferred stock designated, of which there are 2,990,000 shares of $2.25 Noble
Preferred Stock outstanding. In addition, as of May 31, 1994, Noble had reserved
for issuance (i) 3,066,167 shares of Noble Common Stock under Noble's employee
stock option plans, (ii) 325,000 shares of Noble Common Stock under Noble's non-
employee director stock option plan, (iii) 160,000 shares of Noble Common Stock
under certain non-employee director stock option agreements and (iv) 16,204,185
shares of Noble Common Stock on conversion of the outstanding $2.25 Noble
Preferred Stock. In addition, an indeterminate number of shares of Noble Common
Stock (of up to at least 254,551 shares) have been reserved for issuance in
connection with certain contingent obligations under the Triton Agreement.
 
     If the Noble Charter Amendment is adopted by the stockholders of Noble at
the Noble Special Meeting, upon the filing of the amendment with the Delaware
Secretary of State, Noble will have 215,000,000 authorized shares of stock,
consisting of (i) 200,000,000 shares of Noble Common Stock and (ii) 15,000,000
shares of preferred stock. If the Merger Proposal is also approved at the Noble
Special Meeting and the Merger is consummated, up to 4,025,000 shares of
preferred stock of Noble will be designated and issued pursuant to the Merger as
$1.50 Noble Preferred Stock. See "The Merger" and "Proposal to Adopt Noble
Charter Amendment."
 
     The following summary description of the capital stock of Noble is
qualified in its entirety by reference to the Restated Certificate of
Incorporation of Noble, as amended (including the Certificate of Designations
governing the $2.25 Noble Preferred Stock, the "Noble Certificate of
Incorporation"), and the form of Certificate of Designations which will govern
the $1.50 Noble Preferred Stock, copies of which have been filed or incorporated
by reference as exhibits to the Registration Statement.
 
NOBLE COMMON STOCK
 
     Holders of Noble Common Stock are entitled to one vote per share on each
matter to be voted upon by the stockholders of Noble. Dividends may be paid to
the holders of Noble Common Stock when, as and if declared by the Noble Board of
Directors out of funds legally available for such purpose, subject to any
preferential cumulative dividend rights of any preferred stock of Noble,
including the $2.25 Noble Preferred Stock and, if the Merger is consummated, the
$1.50 Noble Preferred Stock, outstanding at the time. Holders of Noble Common
Stock have no conversion, redemption, cumulative voting or preemptive rights. In
the event of any liquidation, dissolution or winding up of Noble, after payment
or provision for payment of the debts and other liabilities of Noble and the
preferential amounts to which the holders of the $2.25 Noble Preferred Stock
and, if the Merger is consummated, the $1.50 Noble Preferred Stock, or any other
series or class of Noble's stock hereafter issued that ranks senior as to
liquidation rights to the Noble Common Stock are entitled, the holders of Noble
Common Stock will be entitled to share ratably in any remaining assets of Noble.
 
     All outstanding shares of Noble Common Stock are, and the shares of Noble
Common Stock to be issued pursuant to the Merger Agreement and upon conversion
of the $1.50 Noble Preferred Stock will be, when issued, duly and validly
issued, fully paid and nonassessable.
 
     The Noble Common Stock is quoted in the NASDAQ National Market System under
the symbol "NDCO."
 
     The transfer agent and registrar for the Noble Common Stock is Liberty Bank
and Trust Company of Oklahoma City, N.A.
 
$2.25 NOBLE PREFERRED STOCK
 
     The Board of Directors of Noble is authorized by the Noble Certificate of
Incorporation to issue preferred stock in one or more series and to fix for each
such series such designation, voting powers, if any, preferences
 
                                       57
<PAGE>   70
 
and relative, participating, optional or other special rights, and such
qualifications, limitations and restrictions thereof, as are stated and adopted
by resolution of the Board without further stockholder approval. No shares of
preferred stock other than the $2.25 Noble Preferred Stock are currently issued
or outstanding.
 
     Dividends. Holders of shares of the $2.25 Noble Preferred Stock are
entitled to receive, when, as and if declared by the Noble Board of Directors
out of funds at the time legally available therefor, cash dividends at an annual
rate of $2.25 per share, and no more, payable quarterly. The $2.25 Noble
Preferred Stock has priority as to dividends over the Noble Common Stock, and no
dividend (other than dividends payable solely in Noble Common Stock) may be
declared, paid or set apart for payment unless all accrued and unpaid dividends
on the $2.25 Noble Preferred Stock have been paid or declared and set apart for
payment. The $2.25 Noble Preferred Stock will rank on a parity with the $1.50
Noble Preferred Stock and no dividend on the $2.25 Noble Preferred Stock may be
declared, paid or set apart for payment unless full cumulative dividends on the
$1.50 Noble Preferred Stock have been or are contemporaneously paid or declared
and set apart for payment. See "-- Restrictions on Dividends."
 
     Liquidation Rights. In the event of any liquidation, dissolution or winding
up of Noble, holders of shares of the $2.25 Noble Preferred Stock are entitled
to receive the liquidation preference of $25.00 per share, plus an amount equal
to any accrued and unpaid dividends to the payment date, and no more, before any
payment or distribution is made to the holders of Noble Common Stock. After
payment in full of the liquidation preference of the shares of $2.25 Noble
Preferred Stock, the holders of such shares will not be entitled to any further
participation in any distribution of assets by Noble. The $2.25 Noble Preferred
Stock will rank on a parity with the $1.50 Noble Preferred Stock and no payment
on account of any liquidation, dissolution or winding up of Noble may be made to
the holders of the $2.25 Noble Preferred Stock unless a proportionate amount is
paid at the same time to the holders of the $1.50 Noble Preferred Stock.
 
     Voting Rights. The holders of the $2.25 Noble Preferred Stock have no
voting rights except as described below or as required by law. In exercising any
such vote, each outstanding share of the $2.25 Noble Preferred Stock is entitled
to one vote.
 
     Whenever dividends on the $2.25 Noble Preferred Stock or the $1.50 Noble
Preferred Stock have not been paid in an aggregate amount equal to at least six
quarterly dividends on such shares (whether or not consecutive), the number of
directors of Noble will be increased by two, and the holders of the $2.25 Noble
Preferred Stock, voting separately as a class together with the holders of the
$1.50 Noble Preferred Stock, will be entitled to elect such two additional
directors to the Board of Directors at any meeting of stockholders of Noble at
which directors are to be elected held during the period such dividends remain
in arrears. Such voting right will terminate when all such dividends accrued and
in default have been paid in full or set apart for payment. The term of office
of all directors so elected will terminate immediately upon such payment or
setting apart for payment.
 
     In addition, so long as any of the $2.25 Noble Preferred Stock is
outstanding, Noble shall not, without the affirmative vote or consent of the
holders of at least 66 2/3 percent of all outstanding shares of the $2.25 Noble
Preferred Stock, voting separately as a class, (i) amend, alter or repeal any
provision of the Certificate of Incorporation or the Bylaws of Noble so as to
affect adversely the relative rights, preferences, qualifications, limitations
or restrictions of the $2.25 Noble Preferred Stock, (ii) authorize or issue, or
increase the authorized amount of, any additional class or series of stock, or
any security convertible into stock of such class or series, ranking senior to
the $2.25 Noble Preferred Stock as to dividends or upon liquidation, dissolution
or winding up of Noble or (iii) effect any reclassification of the $2.25 Noble
Preferred Stock.
 
                                       58
<PAGE>   71
 
     Redemption at Option of Noble. The $2.25 Noble Preferred Stock may not be
redeemed prior to December 31, 1994. The $2.25 Noble Preferred Stock otherwise
is redeemable for cash, in whole or in part, at any time at the option of Noble,
if redeemed during the 12-month period beginning December 31 of the year
specified below, at the following redemption prices:
<TABLE>
<CAPTION>

YEAR                      PRICE PER SHARE
- ----                      ---------------
<S>                           <C>
1994....................      $26.575
1995....................       26.350
1996....................       26.125
1997....................       25.900
 
<CAPTION>
YEAR                      PRICE PER SHARE
- ----                      ---------------
<S>                           <C>
1998....................      $25.675
1999....................       25.450
2000....................       25.225
</TABLE>
 
and thereafter at $25.00 per share, plus in each case accrued and unpaid
dividends to the redemption date.
 
     There is no mandatory redemption or sinking fund obligation with respect to
the $2.25 Noble Preferred Stock. In the event that Noble has failed to pay
accrued and unpaid dividends on the $2.25 Noble Preferred Stock, it may not
redeem any of the then outstanding shares of the $2.25 Noble Preferred Stock
until all such accrued and unpaid dividends and (except with respect to shares
to be redeemed) the then current quarterly dividend have been paid in full.
 
     Conversion Rights. The holder of any shares of the $2.25 Noble Preferred
Stock has the right, at the holder's option, to convert any or all such shares
into Noble Common Stock at any time at a rate (subject to adjustment in the case
of certain dilutive events) of 5.41946 shares of Noble Common Stock for each
share of $2.25 Noble Preferred Stock (equivalent to a conversion price of $4.613
per share of Noble Common Stock).
 
     Special Conversion Rights. Upon the occurrence of certain types of
significant corporate or ownership transactions, the holder of any shares of the
$2.25 Noble Preferred Stock will have a special conversion right designed to
provide limited loss protection, subject to the right of Noble to pay cash in
lieu of conversion securities. Such protection is accomplished by effectively
reducing the conversion price upon any such occurrence, but only to the extent
such reduction does not result in a conversion price that is less than $2.5834
per share of Noble Common Stock (subject to adjustment in the case of certain
dilutive events).
 
     Exchange Provisions. The $2.25 Noble Preferred Stock may be exchanged at
the option of Noble, in whole but not in part, on any dividend payment date
commencing December 31, 1993, for convertible debentures of Noble at a rate of
$25.00 principal amount of debentures for each share of $2.25 Noble Preferred
Stock, provided that all accrued and unpaid dividends to the date of exchange
have been paid and certain other conditions have been met. The debentures would
be unsecured, subordinated obligations of Noble, would be limited in aggregate
principal amount to the aggregate liquidation preference of the $2.25 Noble
Preferred Stock for which the debentures are exchanged, and would mature on
December 31, 2016. Noble would pay interest on the debentures semiannually
following the issue thereof at the rate of nine percent per annum. The holder of
any debenture would have the right, at the holder's option, to convert the
principal amount thereof (or any portion thereof that is an integral multiple of
$25.00) into shares of Noble Common Stock at any time prior to maturity.
 
     The $2.25 Noble Preferred Stock is quoted in the NASDAQ National Market
System under the symbol "NDCOP." The transfer agent, conversion agent and
registrar for the $2.25 Noble Preferred Stock is Liberty Bank and Trust Company
of Oklahoma City, N.A.
 
$1.50 NOBLE PREFERRED STOCK
 
     Upon consummation of the Merger, Noble will issue a new series of preferred
stock consisting of up to 4,025,000 shares and designated as the $1.50
Convertible Preferred Stock (referred to in this Joint Proxy
Statement/Prospectus as the "$1.50 Noble Preferred Stock"). The rights,
privileges, preferences and voting power of the $1.50 Noble Preferred Stock will
be substantially equivalent to those of the Chiles Preferred Stock. All shares
of $1.50 Noble Preferred Stock to be issued pursuant to the Merger Agreement
will be, when issued, duly and validly issued, fully paid and nonassessable.
 
                                       59
<PAGE>   72
 
     The holders of the $1.50 Noble Preferred Stock will have no preemptive
rights with respect to any shares of capital stock of Noble or any other
securities of Noble convertible into or carrying rights or options to purchase
any such shares. The $1.50 Noble Preferred Stock will not be subject to any
sinking fund or other obligation of Noble to redeem or retire the $1.50 Noble
Preferred Stock. Application will be made to list the $1.50 Noble Preferred
Stock in the NASDAQ National Market System. The transfer agent, conversion agent
and registrar for the $1.50 Noble Preferred Stock will be Liberty Bank and Trust
Company of Oklahoma City, N.A.
 
     Ranking. The $1.50 Noble Preferred Stock will rank senior to the Noble
Common Stock, and on a parity with the $2.25 Noble Preferred Stock, with respect
to the payment of dividends and upon liquidation, dissolution or winding up of
Noble.
 
     Dividends. Holders of the $1.50 Noble Preferred Stock will be entitled to
receive, when, as and if declared by the Board of Directors of Noble, out of the
funds of Noble legally available therefor, annual cash dividends at the rate of
$1.50 per share, payable quarterly in arrears on March 31, June 30, September 30
and December 31 of each year, commencing September 30, 1994, or if such day is
not a business day, the next succeeding business day. Dividends on the $1.50
Noble Preferred Stock will be cumulative from the first day of the quarterly
dividend period with respect to the Chiles Preferred Stock during which the
Effective Time occurs, and will be payable to holders of record as they appear
on the stock books of Noble on such record dates, which shall be not more than
60 days nor less than 10 days preceding the payment dates, as shall be fixed by
the Noble Board of Directors, provided that holders of shares of $1.50 Noble
Preferred Stock called for redemption on a redemption date falling between a
dividend payment record date and the dividend payment shall, in lieu of
receiving such dividend on the dividend payment date fixed therefor, receive
such dividend payment together with all other accrued and unpaid dividends on
the date fixed for redemption (unless such holders convert such shares in
accordance with the Certificate of Designation). Dividends payable per share of
$1.50 Noble Preferred Stock for each quarterly dividend period will be computed
by dividing the annual dividend amount by four. The amount of dividends payable
for the initial dividend period and for any period shorter or longer than a full
quarterly dividend period will be computed on the basis of a 360-day year of
twelve 30-day months. Holders of the $1.50 Noble Preferred Stock will not be
entitled to any dividends, whether payable in cash, property or securities, in
excess of the full cumulative dividends, as described above. No interest, or sum
of money in lieu of interest, will be payable in respect of any accrued and
unpaid dividends.
 
     If dividends are not paid in full, or declared in full and sums set apart
for the payment thereof, upon the $1.50 Noble Preferred Stock and upon any other
capital stock ranking on a parity as to dividends with the $1.50 Noble Preferred
Stock (including the $2.25 Noble Preferred Stock), all dividends declared upon
shares of $1.50 Noble Preferred Stock and such other parity stock will be
declared and paid pro rata so that in all cases the amount of dividends declared
per share on the $1.50 Noble Preferred Stock and such other parity stock will
bear to each other the same ratio that accrued and unpaid dividends per share on
the shares of $1.50 Noble Preferred Stock and such other parity stock bear to
each other. Except as set forth above, unless full cumulative dividends on all
outstanding shares of the $1.50 Noble Preferred Stock have been paid or declared
and sums set aside for the payment thereof, dividends (other than dividends paid
in Noble Common Stock or other stock ranking junior to the $1.50 Noble Preferred
Stock as to dividends and upon liquidation, dissolution or winding up) may not
be declared or paid or set apart for payment, and other distributions may not be
made upon the Noble Common Stock or on any other stock of Noble ranking junior
to the $1.50 Noble Preferred Stock as to dividends, or upon liquidation,
dissolution or winding up, nor may any Noble Common Stock or any other stock of
Noble ranking junior to or on a parity with the $1.50 Noble Preferred Stock as
to dividends or upon liquidation, dissolution or winding up be redeemed,
purchased or otherwise acquired for any consideration by Noble (except by
conversion into or exchange for stock of Noble ranking junior to the $1.50 Noble
Preferred Stock as to dividends and upon liquidation, dissolution or winding
up).
 
     Under Delaware law, Noble may declare and pay dividends on its capital
stock only out of surplus, as defined in the DGCL or, in case there is no such
surplus, out of its net profits for the fiscal year in which the dividend is
declared and/or the preceding fiscal year. Surplus under the DGCL is generally
defined to mean the excess, at any given time, of the net assets of a
corporation over the amount of the corporation's capital.
 
                                       60
<PAGE>   73
 
No dividends or distributions may be declared, paid or made if Noble is or would
be rendered insolvent by virtue of such dividend or distribution, or if such
declaration, payment or distribution would contravene the Certificate of
Incorporation. See "-- Restrictions on Dividends."
 
     Liquidation Rights. In the event of any liquidation, dissolution or winding
up of Noble, whether voluntary or involuntary, the holders of shares of $1.50
Noble Preferred Stock will be entitled to receive out of the assets of Noble
available for distribution to stockholders the liquidation preference of $25.00
per share plus an amount equal to all dividends (whether or not earned or
declared) accrued and unpaid to the payment date before any payment or
distribution of assets is made to holders of Noble Common Stock or of any other
class of stock of Noble ranking junior to the $1.50 Noble Preferred Stock upon
liquidation, dissolution or winding up. If upon any liquidation, dissolution or
winding up of Noble, the amounts payable with respect to the $1.50 Noble
Preferred Stock and any other capital stock ranking as to any such distribution
on a parity with the $1.50 Noble Preferred Stock are not paid in full, the
holders of the $1.50 Noble Preferred Stock and of such other parity stock will
share ratably in any such distribution of assets in proportion to the full
respective preferential amounts to which they are entitled. After payment of the
full amount of the liquidation preference to which they are entitled, the
holders of shares of $1.50 Noble Preferred Stock will not be entitled to any
further participation in any distribution of assets by Noble. Neither a
consolidation or merger of Noble with another corporation nor a sale, lease,
exchange or transfer of all or part of Noble's assets for cash, securities or
other property will be considered a liquidation, dissolution or winding up of
Noble for these purposes.
 
     Conversion Rights. Shares of the $1.50 Noble Preferred Stock will be
convertible at any time at the option of the holder thereof at an initial
conversion rate of 2.4446 shares of Noble Common Stock for each share of $1.50
Noble Preferred Stock (equivalent to a conversion price of $10.23 per share of
Noble Common Stock), subject to adjustment as described below, except that, if
shares of $1.50 Noble Preferred Stock are called for redemption, the conversion
right will terminate at the close of business on the date fixed for redemption.
No fractional shares or securities representing fractional shares of Noble
Common Stock will be issued upon conversion; any fractional shares resulting
from conversion will be paid in cash based upon the last reported sales price of
the Noble Common Stock at the close of business on the first trading day
preceding the date of conversion.
 
     In case Noble shall be a party to any transaction (including, without
limitation, a merger, consolidation, statutory share exchange, sale of all or
substantially all of its assets or recapitalization of the Noble Common Stock),
in each case as a result of which shares of Noble Common Stock shall be
converted into the right to receive stock, securities or other property
(including cash or any combination thereof), each share of $1.50 Noble Preferred
Stock remaining outstanding shall thereafter be convertible into the kind and
amount of shares of stock and other securities and property receivable
(including cash) upon the consummation of such transaction by a holder of that
number of shares or fraction thereof of Noble Common Stock into which such share
of $1.50 Noble Preferred Stock was convertible immediately prior to such
transaction.
 
     The conversion price is subject to adjustment upon certain events,
including: (i) the issuance of Noble Common Stock as a dividend or distribution
with respect to the outstanding Noble Common Stock, subdivisions, splits or
combinations of Noble Common Stock, or the issuance of any shares of capital
stock by reclassification of the Noble Common Stock; (ii) the issuance to all
holders of Noble Common Stock of rights or warrants to subscribe for or purchase
Noble Common Stock, in each case at less than the then current market price per
share of Noble Common Stock; and (iii) the payment of a dividend or making of a
distribution to holders of Noble Common Stock of shares of capital stock of
Noble or its subsidiaries (other than Noble Common Stock) or of evidences of its
indebtedness, or of assets, including securities, but excluding those rights,
warrants, dividends and distributions referred to above, dividends and
distributions in connection with the liquidation, dissolution or winding up of
Noble and regular periodic cash dividends payable out of surplus.
 
     No adjustment in the conversion price will be required to be made in any
case until cumulative adjustments amount to one percent or more of the
conversion price as last adjusted, but any such adjustment that would otherwise
be required to be made shall be carried forward and taken into account in any
subsequent adjustment. Noble reserves the right, to the extent permitted by law,
to make such reductions in the
 
                                       61
<PAGE>   74
 
conversion price in addition to those required in the foregoing provisions as
it, in its sole discretion, shall determine to be advisable in order that
certain stock-related distributions hereafter made by Noble to its stockholders
shall not be taxable to such stockholders.
 
     Holders of shares of $1.50 Noble Preferred Stock at the close of business
on a dividend payment record date shall be entitled to receive the dividend
payable on such shares on the corresponding dividend payment date (except that
holders of shares called for redemption on a redemption date falling between
such dividend payment record date and the dividend payment date shall, in lieu
of receiving such dividend on the dividend payment date fixed therefor, receive
such dividend payment together with all other accrued and unpaid dividends on
the date fixed for redemption, unless such holders convert such shares in
accordance with the Certificate of Designations) notwithstanding the conversion
thereof following such dividend payment record date and prior to such dividend
payment date. However, shares of $1.50 Noble Preferred Stock surrendered for
conversion during the period between the close of business on any dividend
payment record date and the opening of business on the corresponding dividend
payment date (except shares of $1.50 Noble Preferred Stock called for redemption
on a redemption date during such period) must be accompanied by payment of an
amount equal to the dividend payment with respect to such shares of $1.50 Noble
Preferred Stock presented for conversion on such dividend payment date. A holder
of shares of $1.50 Noble Preferred Stock on a dividend payment record date who
(or whose transferee) surrenders any such shares for conversion into shares of
Noble Common Stock on the corresponding dividend payment date will receive the
dividend payable by Noble on such shares of $1.50 Noble Preferred Stock on such
date, and the converting holder need not include payment in the amount of such
dividend upon surrender of shares of $1.50 Noble Preferred Stock for conversion
on the dividend payment date. Except as provided above, Noble shall make no
payment or allowance for unpaid dividends, whether or not in arrears, on
converted shares of $1.50 Noble Preferred Stock or for dividends on the shares
of Noble Common Stock issued upon such conversion.
 
     Noble will endeavor to comply with all federal and state securities laws
regulating the offer and delivery of shares of Noble Common Stock upon
conversion of the $1.50 Noble Preferred Stock and will endeavor to have approved
for listing, in the NASDAQ National Market System or on any national securities
exchange upon which the Noble Common Stock is listed, the shares of Noble Common
Stock deliverable upon conversion of the $1.50 Noble Preferred Stock.
 
     Right of Redemption of Noble. Shares of the $1.50 Noble Preferred Stock
will not be redeemable prior to December 31, 1996. The shares of $1.50 Noble
Preferred Stock will be redeemable at the option of Noble, in whole or in part,
at any time or from time to time, out of funds legally available therefor, on or
after December 31, 1996, on not less than 30 nor more than 60 days' notice by
first-class mail at the redemption prices per share of $1.50 Noble Preferred
Stock set forth below during the 12-month periods beginning on December 31 of
the years shown below, plus in each case an amount equal to accrued and unpaid
dividends, if any, to (and including) the redemption date, whether or not earned
or declared (the "Redemption Price").
<TABLE>
<CAPTION>

YEAR                      PRICE PER SHARE
- ----                      ---------------
<S>                           <C>
1996....................      $ 26.05
1997....................        25.90
1998....................        25.75
1999....................        25.60
 
<CAPTION>
YEAR                      PRICE PER SHARE
- ----                      ---------------
<S>                           <C>
2000....................      $ 25.45
2001....................        25.30
2002....................        25.15
2003 and thereafter.....        25.00
</TABLE>
 
     If fewer than all of the outstanding shares of $1.50 Noble Preferred Stock
are to be redeemed, the shares to be redeemed shall be selected by lot or pro
rata or in some other equitable manner determined by the Board of Directors of
Noble in its sole discretion. There is no mandatory redemption or sinking fund
obligation with respect to the $1.50 Noble Preferred Stock. In the event that
Noble has failed to pay accrued and unpaid dividends on the $1.50 Noble
Preferred Stock, it may not redeem less than all of the then outstanding shares
of the $1.50 Noble Preferred Stock until all such accrued and unpaid dividends
and the then current quarterly dividends have been paid in full. After the date
fixed for redemption, unless Noble is in default in providing money for the
payment of the Redemption Price, dividends shall cease to accrue on the $1.50
Noble Preferred Stock called for redemption, such shares shall no longer be
deemed to be outstanding and all rights of the
 
                                       62
<PAGE>   75
 
holders of such shares as stockholders of Noble shall cease, except the right to
receive the moneys payable upon such redemption, without interest thereon, upon
surrender of the certificates evidencing such shares.
 
     Voting Rights. The holders of the $1.50 Noble Preferred Stock will have no
voting rights, except as described below or as required by law. In exercising
any such vote, each outstanding share of $1.50 Noble Preferred Stock will be
entitled to one vote, excluding shares held by Noble or any entity controlled by
Noble, which shares shall have no voting rights.
 
     Whenever dividends on the $1.50 Noble Preferred Stock have not been paid in
an aggregate amount equal to at least six quarterly dividends on such shares
(whether or not consecutive), the holders of the $1.50 Noble Preferred Stock
(voting separately as a class with the holders of any stock ranking on a parity
as to dividends with the $1.50 Noble Preferred Stock on which like voting rights
have been conferred and are exercisable, including the $2.25 Noble Preferred
Stock) will be entitled to elect two directors to the Board of Directors either
by written consent or at any meeting of stockholders of Noble at which directors
are to be elected held during the period such dividends remain in arrears. Such
voting rights will terminate when all such dividends accrued and in default have
been paid in full or declared and funds set apart for payment in full. The term
of office of all directors so elected will terminate immediately upon such
payment or setting apart for payment.
 
     In addition, without the affirmative vote or consent of the holders of at
least 66 2/3 percent of shares of the $1.50 Noble Preferred Stock then
outstanding, voting separately as a class, Noble may not (i) authorize, create,
issue or increase the authorized number of shares of any class or classes or
series of stock, or any security convertible into stock of such class or series,
ranking prior to the $1.50 Noble Preferred Stock either as to dividends or upon
liquidation, dissolution or winding up of Noble, (ii) amend, alter or repeal
(whether by merger, consolidation or otherwise) any of the provisions of the
Certificate of Incorporation (including the Certificate of Designation) of Noble
so as to affect adversely any right, preference, privilege or voting power of
the $1.50 Noble Preferred Stock or the holders thereof or (iii) authorize any
reclassification of the $1.50 Noble Preferred Stock. Without the affirmative
vote or consent of holders of at least 50 percent of the shares of $1.50 Noble
Preferred Stock then outstanding, Noble may not increase the amount of
authorized $1.50 Noble Preferred Stock or create additional classes of stock or
issue series of capital stock ranking on a parity with the $1.50 Noble Preferred
Stock with respect to the payment of dividends or upon liquidation, dissolution
and winding up of Noble. However, Noble may increase the amount of authorized
preferred stock or create additional classes of stock or issue series of capital
stock ranking junior to the $1.50 Noble Preferred Stock with respect to the
payment of dividends and upon liquidation, dissolution and winding up of Noble
without the consent of any holder of $1.50 Noble Preferred Stock.
 
     Special Conversion Rights. The $1.50 Noble Preferred Stock has a special
conversion right that becomes effective upon the occurrence of certain types of
significant transactions affecting ownership or control of Noble or the market
for the Noble Common Stock. The purpose of the special conversion right is to
provide (subject to certain exceptions) partial loss protection upon the
occurrence of a Change of Control or a Fundamental Change (each as defined
below) at a time when the Market Value (as defined below) of the Noble Common
Stock issuable upon conversion by a holder at the prevailing conversion price is
less than the amount to which the holder would be entitled upon redemption. In
such situations, the special conversion right would, for a limited period,
reduce the then prevailing conversion price to the higher of the Market Value of
the Noble Common Stock or a minimum conversion price of $6.53 per share of Noble
Common Stock, subject to certain adjustments (and increase the equivalent
conversion ratio accordingly). Consequently, to the extent that the Market Value
of the Noble Common Stock is less than the minimum conversion price, a holder
will have a lesser degree of protection from loss upon exercise of a special
conversion right.
 
     The special conversion right is intended to provide limited loss protection
to investors in certain circumstances, while not giving holders a veto power
over significant transactions affecting ownership or control of Noble. Although
the special conversion right may render more costly or otherwise inhibit certain
proposed transactions, its purpose is not to inhibit or discourage takeovers or
other business combinations.
 
     Each holder of the $1.50 Noble Preferred Stock will be entitled to a
special conversion right if a Change of Control or Fundamental Change occurs. A
Change of Control will occur if a person or group acquires more
 
                                       63
<PAGE>   76
 
than 55 percent of the Noble Common Stock. A Fundamental Change is, generally, a
sale of all or substantially all of Noble's assets or a transaction in which at
least 55 percent of the Noble Common Stock is transferred for, or is converted
into, any other asset. However, if the majority of the value of the
consideration received in a transaction by holders of Noble Common Stock is
Marketable Stock (as defined below) or if the holders of Noble Common Stock hold
a majority of the Voting Stock (as defined below) of Noble's successor, the
transaction will not be a Fundamental Change, and holders of the $1.50 Noble
Preferred Stock will not have special conversion rights as the result of that
transaction.
 
     A special conversion right will permit a holder of $1.50 Noble Preferred
Stock, at the holder's option during the 30-day period described in the
following paragraph, to convert all, but not less than all, the holder's $1.50
Noble Preferred Stock at a conversion price equal to the Special Conversion
Price, as defined below. A holder exercising a special conversion right will
receive Noble Common Stock if a Change of Control occurs and, if a Fundamental
Change occurs, will receive the same consideration received for the number of
shares of Noble Common Stock into which the holder's $1.50 Noble Preferred Stock
would have been convertible at the Special Conversion Price. In either case,
however, Noble or its successor may, at its option, elect to pay to the holder
cash equal to the Market Value of the number of shares of Noble Common Stock
into which the holder's $1.50 Noble Preferred Stock is convertible at the
Special Conversion Price.
 
     Noble will mail to each registered holder of $1.50 Noble Preferred Stock a
notice setting forth details of any special conversion right occasioned by a
Change of Control or Fundamental Change within 30 days after the event occurs. A
special conversion right may be exercised only within the 30-day period after
the notice is mailed and will expire at the end of that period. Exercise of a
special conversion right, to the extent permitted by law, is irrevocable, and
all $1.50 Noble Preferred Stock surrendered for conversion will be converted at
the end of the 30-day period mentioned in the preceding sentence. Noble, in
taking any action in connection with any Change of Control, Fundamental Change
or related special conversion right, will undertake to comply with all
applicable federal securities regulations including, to the extent applicable,
Rules 13e-4 and 14e-1 under the Exchange Act.
 
     The $1.50 Noble Preferred Stock that is not converted pursuant to a special
conversion right will continue to be convertible pursuant to the general
conversion rights described under the caption "Conversion Rights" above.
 
     The special conversion right is not intended to, and does not, protect
holders of $1.50 Noble Preferred Stock in all circumstances that might affect
ownership or control of Noble or the market for the Noble Common Stock or that
might otherwise adversely affect the value of an investment in the $1.50 Noble
Preferred Stock. The ability to control Noble may be obtained by a person even
if that person does not, as is required to constitute a Change of Control,
acquire 55 percent of Noble's voting stock. Noble and the market for the Noble
Common Stock may be affected by various transactions that do not constitute a
Fundamental Change. In particular, transactions involving the transfer or
conversion of less than 55 percent of the Noble Common Stock may have a
significant effect on Noble and the market for the Noble Common Stock, as could
transactions in which holders of Noble Common Stock receive primarily Marketable
Stock or continue to own a majority of the Voting Stock of the successor to
Noble. In addition, if the special conversion right does arise as the result of
a Fundamental Change, the special conversion right will allow a holder
exercising a special conversion right to receive the same type of consideration
received by the holders of Noble Common Stock and, thus, the degree of
protection afforded by the special conversion right may be affected by the type
of consideration received.
 
     As used herein, a "Change of Control" with respect to Noble shall be deemed
to have occurred at the first time after the first issuance of any $1.50 Noble
Preferred Stock that any person (within the meaning of Sections 13(d)(3) and
14(d)(2) of the Exchange Act), including a group (within the meaning of Rule
13d-5 under the Exchange Act), together with any of its Affiliates or Associates
(as defined below), files or becomes obligated to file a report (or any
amendment or supplement thereto) on Schedule 13D or 14D-1 pursuant to the
Exchange Act disclosing that such person has become the beneficial owner of
either (i) more than 55 percent of the shares of Noble Common Stock then
outstanding or (ii) securities representing more than 55 percent of the combined
voting power of the Voting Stock (as defined below) then outstanding; provided
that
 
                                       64
<PAGE>   77
 
a Change of Control will not be deemed to have occurred with respect to any
transaction that constitutes a Fundamental Change. An "Affiliate" of a specified
person is a person that directly or indirectly controls, or is controlled by or
is under common control with, the person specified. An "Associate" of a person
means (a) any corporation or organization, other than Noble or any subsidiary of
Noble, of which the person is an officer or partner or is, directly or
indirectly, the beneficial owner of 10 percent or more of any class of equity
securities, (b) any trust or estate in which the person has a substantial
beneficial interest or as to which the person serves as trustee or in a similar
fiduciary capacity and (c) any relative or spouse of the person, or any relative
of the spouse, who has the same home as the person or who is a director or
officer of the person or any of its parents or subsidiaries. As used herein, a
person shall be deemed to have "beneficial ownership" with respect to, and shall
be deemed to "beneficially own," any securities of Noble in accordance with
Section 13 of the Exchange Act and the rules and regulations (including Rule
13d-3, Rule 13d-5 and any successor rules) promulgated by the Commission
thereunder; provided that a person shall be deemed to have beneficial ownership
of all securities that any such person has a right to acquire whether such right
is exercisable immediately or only after the passage of time and without regard
to the 60-day limitation referred to in Rule 13d-3.
 
     As used herein, a "Fundamental Change" with respect to Noble means (i) the
occurrence of any transaction or event in connection with which 55 percent or
more of the outstanding Noble Common Stock is exchanged for, converted into,
acquired for or constitutes solely the right to receive cash, securities,
property or other assets (whether by means of an exchange offer, liquidation,
tender offer, consolidation, merger, combination, reclassification,
recapitalization or otherwise) or (ii) the conveyance, sale, lease, assignment,
transfer or other disposal of all or substantially all of Noble's property,
business or assets; provided, however, that a Fundamental Change will not be
deemed to have occurred with respect to either of the following transactions or
events: (a) any transaction or event in which more than 50 percent (by value as
determined in good faith by the Board of Directors) of the consideration
received by holders of Noble Common Stock consists of Marketable Stock (as
defined below) or (b) any consolidation or merger of Noble in which the holders
of Noble Common Stock immediately prior to such transaction own, directly or
indirectly, (1) 50 percent or more of the common stock of the sole surviving
corporation (or of the ultimate parent of such sole surviving corporation)
outstanding at the time immediately after such consolidation or merger and (2)
securities representing 50 percent or more of the combined voting power of the
surviving corporation's Voting Stock (or of the Voting Stock of the ultimate
parent of such surviving corporation) outstanding at such time. There is no
established meaning of what constitutes a sale of "all or substantially all" of
a company's property, business or assets. This uncertainty may make it difficult
for a holder to determine whether or not a "Fundamental Change" has occurred,
and thus, whether he is entitled to a special conversion right respecting the
shares of $1.50 Noble Preferred Stock held by him.
 
     As used herein, "Voting Stock" means, with respect to any person, capital
stock of such person having general voting power under ordinary circumstances to
elect at least a majority of the board of directors, managers or trustees of
such person (irrespective of whether or not at the time capital stock of any
other class or classes shall have or might have voting power by reason of the
happening of any contingency).
 
     As used herein, "Special Conversion Price" means (i) the higher of (a) the
Market Value of the Noble Common Stock or (b) $6.53 per share (which amount
will, each time the conversion price is adjusted, be adjusted so that the ratio
of such amount to the conversion price, after giving effect to any such
adjustment, shall always be the same as the ratio of $6.53 to the initial
conversion price, without giving effect to any such adjustment) multiplied by
(ii) a ratio the numerator of which is $25.00 and the denominator of which is
the Redemption Price (or, if prior to the date on which Noble may begin to
redeem the $1.50 Noble Preferred Stock, the Redemption Price applicable
commencing on such date).
 
     As used herein, "Market Value" of the Noble Common Stock or any other
Marketable Stock is the average of the last reported sales prices of the Noble
Common Stock or such other Marketable Stock, as the case may be, for the five
trading days ending on the last trading day preceding the date of the
Fundamental Change or Change of Control; provided, however, that if the
Marketable Stock is not traded on any national securities exchange or similar
quotation system as described in the definition of "Marketable Stock" during
such period, then the Market Value of such Marketable Stock is the average of
the last reported sales prices
 
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<PAGE>   78
 
per share of such Marketable Stock during the first five trading days commencing
with the first day after the date on which such Marketable Stock was first
distributed to the general public and traded on the New York Stock Exchange, the
American Stock Exchange, the NASDAQ National Market System or any similar system
of automated dissemination of quotations of securities prices in the United
States.
 
     As used herein, the term "Marketable Stock" means Noble Common Stock or
common stock of any corporation that is the successor to all or substantially
all of the business or assets of Noble as a result of a Fundamental Change or of
the ultimate parent of such successor, which is (or will, upon distribution
thereof, be) listed or quoted on the New York Stock Exchange, the American Stock
Exchange, the NASDAQ National Market System or any similar system of automated
dissemination of quotations of securities prices in the United States.
 
FEDERAL INCOME TAX CONSIDERATIONS REGARDING $1.50 NOBLE PREFERRED STOCK
 
     The following is a summary of the material federal income tax consequences
of acquiring, owning and disposing of the $1.50 Noble Preferred Stock and unless
otherwise noted represents the opinion of Thompson & Knight, A Professional
Corporation, counsel to Noble ("Counsel"). This summary does not purport to be
complete and does not address the tax consequences to holders that are subject
to special tax rules, such as banks, insurance companies, regulated investment
companies, personal holding companies, corporations subject to the alternative
minimum tax, S corporations, foreign entities, nonresidential alien individuals,
broker-dealers and tax-exempt entities. Each stockholder or prospective
stockholder should consult his or her own tax advisor with respect to his or her
own particular circumstances.
 
     This summary is based on the Code, Treasury regulations and proposed
regulations, court decisions and current administrative rulings and
pronouncements of the IRS, all of which are subject to change, possibly with
retroactive effect. Also, this summary assumes that the $1.50 Noble Preferred
Stock to be issued in connection with the Merger will be held as a capital asset
(generally, property held for investment) as defined in the Code.
 
     Dividends. Distributions with respect to $1.50 Noble Preferred Stock will
constitute "dividends" for federal income tax purposes to the extent that Noble
has current or accumulated earnings and profits for federal income tax purposes.
Distributions paid to corporations that qualify as "dividends" for federal
income tax purposes will generally be eligible for the 70 percent dividends
received deduction under Section 243 of the Code, subject to the limitations
discussed below. If a distribution with respect to $1.50 Noble Preferred Stock
exceeds the holder's allocable share of Noble's current and accumulated earnings
and profits, the excess will be treated as a nontaxable return of capital which
will reduce the stockholder's tax basis in the $1.50 Noble Preferred Stock; any
amount in excess of the holder's basis will be treated as capital gain. A
reduction in tax basis could result in increased capital gain upon a sale or
other disposition of the $1.50 Noble Preferred Stock.
 
     In general, the dividends received deduction will be available with respect
to dividends on $1.50 Noble Preferred Stock held for at least 46 days, or at
least 91 days in the case of a dividend attributable to a period or periods
aggregating more than 366 days. A stockholder's holding period for these
purposes will be reduced by periods during which the stockholder has an option
to sell, is under a contractual obligation to sell, has made (but not closed) a
short sale of, or is the grantor of an option to purchase, substantially
identical stock or securities. A stockholder's holding period also will be
reduced where the stockholder's risk of loss with respect to the $1.50 Noble
Preferred Stock is considered diminished by reason of the stockholder's holding
one or more other positions in substantially similar or related property,
including (under proposed regulations) a short sale of Noble Common Stock if
price changes of the Noble Common Stock are related to price changes on the
$1.50 Noble Preferred Stock. The dividends received deduction also will not be
available if the stockholder is under an obligation to make related payments
with respect to positions in substantially similar or related property. The
dividends received deduction generally will be limited to 70 percent of the
stockholder's taxable income. The dividends received deduction will be
proportionately reduced to the extent the holder has indebtedness "directly
attributable" to its investment in the $1.50 Noble Preferred Stock. Prospective
corporate purchasers of $1.50 Noble Preferred Stock should consult their own tax
advisors to determine whether these limitations might apply to them.
 
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<PAGE>   79
 
     Extraordinary Dividends. If a corporate holder receives an "extraordinary
dividend" from Noble with respect to $1.50 Noble Preferred Stock which it has
not held for more than two years before the dividend announcement date, the
holder's basis in the $1.50 Noble Preferred Stock will be reduced (but not below
zero) by the portion of the dividend which is deductible by reason of the
dividends received deduction. If, because of the limitation on reducing basis
below zero, any portion of an extraordinary dividend that is deductible by
reason of the dividends received deduction has not been applied to reduce basis,
such amount will be treated as gain from the sale or exchange of stock upon the
sale or disposition of the $1.50 Noble Preferred Stock. An "extraordinary
dividend" on the $1.50 Noble Preferred Stock would include a dividend that (i)
equals or exceeds five percent of the holder's adjusted tax basis in the stock,
treating all dividends having ex-dividend dates within an 85-day period as one
dividend or (ii) exceeds 20 percent of the holder's adjusted tax basis
(determined without regard to any reduction for the non-taxed portion of prior
extraordinary dividends) in the stock, treating all dividends having ex-dividend
dates within a 365-day period as one dividend. A holder may elect to use the
fair market value of the stock as of the day before the ex-dividend date rather
than its adjusted basis for purposes of applying the five percent or 20 percent
limitation if the holder is able to establish such fair market value to the
satisfaction of the IRS. An "extraordinary dividend" would also include any
amount treated as a dividend in the case of a redemption of the $1.50 Noble
Preferred Stock that is non-pro rata as to all stockholders, without regard to
the period the holder held the stock.
 
     Special rules apply with respect to a "qualified preferred dividend," which
would include any fixed dividend payable with respect to the $1.50 Noble
Preferred Stock provided the $1.50 Noble Preferred Stock is not in arrears as to
the dividends when acquired and the actual rate of return on the $1.50 Noble
Preferred Stock does not exceed 15 percent calculated by reference to the lower
of the stockholder's basis in the $1.50 Noble Preferred Stock or its liquidation
preference. The extraordinary dividend rules will not apply to a qualified
preferred dividend if the stockholder has held the $1.50 Noble Preferred Stock
for more than five years. If the stockholder disposes of the $1.50 Noble
Preferred Stock before it has been held for more than five years, the aggregate
reduction in basis will not exceed the excess of the qualified preferred
dividends paid during the period held by the stockholder over the qualified
preferred dividends which would have been paid during such period on the basis
of the stated rate of return calculated by reference to the lower of the
stockholder's basis in the $1.50 Noble Preferred Stock or its liquidation
preference.
 
     The length of time that a stockholder is deemed to have held $1.50 Noble
Preferred Stock for purposes of the extraordinary dividend rules is determined
under principles similar to those applicable for purposes of the dividends
received deduction discussed above.
 
     Redemption Premium. All or a portion of any excess of the Redemption Price
over the issue price of the $1.50 Noble Preferred Stock could be considered to
constitute an unreasonable redemption premium taxable as a dividend to the
extent of Noble's current or accumulated earnings and profits. Any such premium
will not be considered to be unreasonable if it is in the nature of a penalty
for a premature redemption and if such premium does not exceed the amount which
Noble would be required to pay for such redemption right under market conditions
existing at the time of issuance of the $1.50 Noble Preferred Stock. Noble
believes that the redemption premium is reasonable under this standard, but
there can be no assurance that the IRS or the courts will agree therewith, and
Counsel renders no opinion with respect thereto. If, however, any portion of the
redemption premium payable on the $1.50 Noble Preferred Stock were considered
unreasonable under the foregoing rules, a holder of the $1.50 Noble Preferred
Stock would take the amount of such premium into income over the period during
which the stock cannot be called for redemption under the economic accrual
method of Section 1272 of the Code. The Revenue Reconciliation Act of 1990
authorized the Treasury Department to promulgate new regulations regarding the
federal income tax treatment of redemption premiums with respect to preferred
stock. As of this date, certain proposed regulations have been issued. The
primary focus of the proposed regulations is on the treatment of preferred stock
callable at a premium at the option of the issuer. In general, such proposed
regulations are to apply prospectively (only to stock issued on or after final
regulations are issued) and, therefore, it is not anticipated that the proposed
regulations will apply to the $1.50 Noble Preferred Stock. It is not known to
what extent final regulations will incorporate or modify the proposed
regulations or to what extent other new regulations will incorporate or modify
the existing rules referred to above.
 
                                       67
<PAGE>   80
 
     Redemption for Cash. A redemption of shares of $1.50 Noble Preferred Stock
by Noble for cash will be treated under Section 302 of the Code as a
distribution taxable as a dividend to redeeming stockholders to the extent of
Noble's current or accumulated earnings and profits unless the redemption (i)
results in a "complete termination" of the stockholder's interest in Noble
(within the meaning of Section 302(b)(3) of the Code), (ii) is "substantially
disproportionate" (within the meaning of Section 302(b)(2) of the Code) with
respect to the holder or (iii) is "not essentially equivalent to a dividend"
(within the meaning of Section 302(b)(1) of the Code). In determining whether
any of the Code Section 302(b) tests have been met, shares of Noble Common Stock
and of any other class of stock of Noble will be taken into account along with
shares of $1.50 Noble Preferred Stock. Moreover, shares considered to be owned
by the holder by reason of the constructive ownership rules set forth in Section
318 of the Code, as well as shares actually owned, will be taken into account.
If any of the foregoing tests is met, then, except with respect to declared and
unpaid dividends, if any, the redemption of shares of $1.50 Noble Preferred
Stock for cash will result in taxable gain or loss equal to the difference
between the amount of cash received and the holder's tax basis in the redeemed
shares. Any such gain or loss will be capital gain or loss and will be long-term
capital gain or loss if the stockholder's holding period exceeds one year. Based
on a published IRS ruling, the redemption of a stockholder's $1.50 Noble
Preferred Stock for cash should be treated as "not essentially equivalent to a
dividend" if, taking into account the constructive ownership rules, (a) the
stockholder's relative stock interest in Noble is minimal, (b) the stockholder
exercises no control over Noble's affairs and (c) there is a reduction in the
holder's proportionate interest in Noble.
 
     If a redemption of $1.50 Noble Preferred Stock is treated as a dividend
under the rules set forth in the preceding paragraphs, then the holder's tax
basis in the redeemed $1.50 Noble Preferred Stock will be transferred to any
remaining stock in Noble held by such holder. If the holder does not retain any
stock ownership in Noble, then such holder may lose that basis completely.
 
     Also, if a redemption of the $1.50 Noble Preferred Stock is treated as a
dividend, then under the "extraordinary dividend" provisions discussed above, a
corporate holder that has not held the $1.50 Noble Preferred Stock for more than
two years before the date of the announcement of the dividend (or regardless of
its holding period in the case of a redemption that is not pro rata as to all
stockholders) may be required to reduce its basis in its remaining shares of
stock in Noble (and possibly recognize gain upon a disposition of such shares)
to the extent the holder has received the benefit of the 70 percent dividends
received deduction with respect to the dividend.
 
     Conversion into Noble Common Stock. No gain or loss generally will be
recognized upon conversion of shares of $1.50 Noble Preferred Stock into shares
of Noble Common Stock, except with respect to any cash paid in lieu of
fractional shares of Noble Common Stock. The tax basis of the Noble Common Stock
received upon conversion will be equal to the tax basis of the shares of $1.50
Noble Preferred Stock converted, reduced by the portion of such basis
attributable to fractional shares surrendered for cash and increased, in the
case of a conversion after a dividend record date but before the corresponding
dividend payment date, by the amount of such dividend required to be paid to
Noble. The holding period of the Noble Common Stock will include the holding
period of the shares of $1.50 Noble Preferred Stock converted.
 
     Adjustment of Conversion Price. Holders of $1.50 Noble Preferred Stock may
be deemed to have received a constructive distribution of stock that is taxable
as a dividend where the conversion ratio of the $1.50 Noble Preferred Stock is
adjusted unless the change in conversion ratio is made pursuant to a bona fide
reasonable adjustment formula which has the effect of preventing the dilution of
the interest of the holders. Adjustments to compensate for taxable distributions
of cash or property to other stockholders are not considered as made pursuant to
a bona fide adjustment formula. In addition, certain of the possible adjustments
provided with respect to the $1.50 Noble Preferred Stock (including those in
connection with the special conversion rights applicable to the $1.50 Noble
Preferred Stock) may not qualify as being pursuant to a bona fide reasonable
adjustment formula. If a nonqualifying adjustment were made, the holders of
$1.50 Noble Preferred Stock could be deemed to have received a taxable stock
dividend.
 
     Backup Withholding. Under the backup withholding provisions of the Code and
applicable Treasury regulations, a holder of $1.50 Noble Preferred Stock may be
subject to backup withholding at the rate of 31
 
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<PAGE>   81
 
percent with respect to dividends on, or the proceeds of a sale, conversion or
redemption of, the $1.50 Noble Preferred Stock, unless such holder (i) is a
corporation or comes within certain other exempt categories and when required
demonstrates this fact or (ii) provides a taxpayer identification number,
certifies as to no loss of exemption from backup withholding and otherwise
complies with applicable requirements of the backup withholding rules. The
amount of any backup withholding from a payment to a holder will be allowed as a
credit against the holder's federal income tax liability and may entitle such
holder to a refund, provided that the required information is furnished to the
IRS.
 
RESTRICTIONS ON DIVIDENDS
 
     Senior Note Indenture. Certain provisions of the indenture (the "Senior
Note Indenture") governing Noble's outstanding 9 1/4% Senior Notes Due 2003 (the
"Senior Notes") restrict Noble's ability to pay cash dividends on Noble Common
Stock and will restrict Noble's ability to pay cash dividends on the $1.50 Noble
Preferred Stock. Under the Senior Note Indenture, Noble may not make certain
Restricted Payments (as defined in the Senior Note Indenture), including
dividends and other payments with respect to Noble Common Stock and $1.50 Noble
Preferred Stock, if (i) a default under the Senior Note Indenture is continuing
or would result from such Restricted Payment; (ii) for the 12-month period
ending on the last day of Noble's most recently completed fiscal quarter,
Noble's consolidated interest coverage ratio was less than (A) 2.0:1, for any
such payment occurring on or prior to December 31, 1995, or (B) 2.5:1, for any
such payment occurring on or after January 1, 1996; or (iii) after giving effect
to such Restricted Payment, the aggregate amount of all Restricted Payments
since October 7, 1993, the date of issuance of the Senior Notes, exceeds the sum
(such sum, the "Restricted Payment Basket") of (A) 50 percent of the aggregate
consolidated net income (as defined) of Noble (or if such consolidated net
income is a deficit, minus 100 percent of such deficit) accrued during the
period beginning on October 1, 1993 and ending on the last day of the fiscal
quarter ending immediately prior to the date of such proposed Restricted
Payment; (B) the aggregate net cash proceeds to Noble from the sale of certain
capital stock of Noble subsequent to October 7, 1993 and the liability
(expressed as a positive number) of any indebtedness of Noble, or the carrying
value of any redeemable stock of Noble (including the $2.25 Noble Preferred
Stock), which has been converted into shares of Noble Common Stock subsequent to
October 7, 1993; and (C) $10,000,000. The provisions of the Senior Note
Indenture described above do not directly prevent Noble from paying regular cash
dividends on the $2.25 Noble Preferred Stock. However, the aggregate amount of
such dividends paid by Noble are taken into account as Restricted Payments for
purposes of subsequent computations of the aggregate amount of all Restricted
Payments under the provisions of the Senior Note Indenture described in clause
(iii) above.
 
     The payment of dividends on the $1.50 Noble Preferred Stock will constitute
Restricted Payments for all purposes of the Senior Note Indenture, and,
accordingly, will be subject to the Restricted Payment Basket. To the extent
that the payment of dividends on Noble Common Stock, $2.25 Noble Preferred Stock
and $1.50 Noble Preferred Stock would result in the aggregate amount of all
Restricted Payments made by Noble exceeding the Restricted Payment Basket, and
during such times that the aggregate amount of all Restricted Payments exceeds
the Restricted Payment Basket, dividend payments on Noble Common Stock and $1.50
Noble Preferred Stock will be prohibited under the provisions of the Senior Note
Indenture. The $1.50 Noble Preferred Stock will rank on a parity with the $2.25
Noble Preferred Stock with respect to the payment of dividends, which means that
no dividends may be paid on the $2.25 Noble Preferred Stock unless accrued
dividends on the $1.50 Noble Preferred Stock are also paid. Accordingly, if the
payment of accrued dividends on the $1.50 Noble Preferred Stock is prohibited
pursuant to the Senior Note Indenture, dividend payments on the $2.25 Noble
Preferred Stock will also be prohibited.
 
     As of March 31, 1994, Noble's consolidated interest coverage ratio was
5.1:1 and the amount of the Restricted Payment Basket was $15,027,000. As of
that same date, Noble had made Restricted Payments (consisting of regular
dividends on the $2.25 Noble Preferred Stock) since October 7, 1993 of
$3,364,000, leaving $11,663,000 of the Restricted Payment Basket available, as
of March 31, 1994, for Restricted Payments. Annual dividends on the currently
outstanding shares of $2.25 Noble Preferred Stock total $6,727,500. Annual
dividends on 4,025,000 shares of $1.50 Noble Preferred Stock (which is the
maximum
 
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<PAGE>   82
 
number of shares of $1.50 Noble Preferred Stock issuable in connection with the
Merger upon conversion and exchange of the Chiles Preferred Stock) will total
$6,037,500.
 
     As of March 31, 1994, the aggregate carrying value of the outstanding
shares of $2.25 Noble Preferred Stock was approximately $71,760,000. The $2.25
Noble Preferred Stock is convertible into Noble Common Stock at any time at a
rate (subject to adjustment in the case of certain dilutive events) of 5.41946
shares of Noble Common Stock for each share of such preferred stock (equivalent
to a conversion price of $4.613 per share of Noble Common Stock). The $2.25
Noble Preferred Stock is also redeemable at the option of Noble at any time on
and after December 31, 1994, initially at a redemption price of $26.575 per
share, and thereafter at prices decreasing ratably annually to $25.00 per share
on and after January 1, 2002, plus accrued and unpaid dividends. See
"Description of Noble Capital Stock -- $2.25 Noble Preferred Stock." To the
extent that shares of $2.25 Noble Preferred Stock are converted into shares of
Noble Common Stock as a result of a call for redemption of such preferred stock
or otherwise, the carrying value of such converted shares of preferred stock
will be added to the Restricted Payment Basket. Giving effect to an assumed full
conversion on December 31, 1994 of the $2.25 Noble Preferred Stock, and assuming
(i) the amount of the Restricted Payment Basket remains unchanged from March 31,
1994 through December 31, 1994 and (ii) no Restricted Payments are made during
such period other than regular cash dividends on the $2.25 Noble Preferred Stock
and, after the Effective Time, the $1.50 Noble Preferred Stock, the amount of
the Restricted Payment Basket available for Restricted Payments as of December
31, 1994 would be $77,059,000. There can be no assurance as to when or if a
full, or any partial, conversion of the $2.25 Noble Preferred Stock will occur.
 
     Credit Agreement. On June 16, 1994, Noble entered into a credit agreement
(the "Credit Agreement") with two banks providing for a $25 million revolving
line of credit. Certain provisions of the Credit Agreement restrict Noble's
ability to pay cash dividends on Noble Common Stock and $2.25 Noble Preferred
Stock and will restrict Noble's ability to pay cash dividends on the $1.50 Noble
Preferred Stock. Under the Credit Agreement, Noble may not make certain
Restricted Payments (as defined in the Credit Agreement), including dividends
and other payments with respect to Noble Common Stock, $2.25 Noble Preferred
Stock and $1.50 Noble Preferred Stock, if (i) a default under the Credit
Agreement is continuing or would result from such Restricted Payment; (ii)
Noble's tangible net worth is less than the sum of (A) $280,000,000, plus (B) 50
percent of any positive net income of Noble computed on a cumulative basis for
the period beginning April 30, 1994 and ending on the last day of the fiscal
quarter immediately preceding the date of any determination, with no negative
adjustment to be made in the event net income is a deficit figure for any fiscal
period, plus (C) 85 percent of the aggregate amount of net non-cash proceeds,
and 100 percent of net cash proceeds, to Noble from the issuance or sale after
April 30, 1994, and determined as of the last day of each fiscal quarter
subsequent to March 31, 1994, of (x) shares of Noble Common Stock or warrants,
rights or options to purchase or acquire Noble Common Stock and (y) shares of
preferred stock of Noble, provided that such 85 percent rate will increase to
100 percent at such time as the aggregate of all net noncash proceeds from the
sale by Noble of Noble Common Stock, or warrants, rights or options to purchase
or acquire Noble Common Stock, exceeds $300,000,000; or (iii) Noble's debt to
capital ratio exceeds 0.35:1.
 
     As of March 31, 1994, Noble's tangible net worth was approximately
$326,000,000, and the minimum tangible net worth required under the provisions
of the Credit Agreement to allow Restricted Payments, calculated as set forth in
the Credit Agreement and as generally described above, was $280,000,000. As of
March 31, 1994, Noble's debt to capital ratio was 0.28:1. As of March 31, 1994,
Noble's and Chiles' pro forma combined net worth was approximately $516,000,000,
and the minimum tangible net worth required under the provisions of the Credit
Agreement to allow Restricted Payments, calculated as set forth in the Credit
Agreement and generally described above, was $441,500,000. As of March 31, 1994,
Noble's and Chiles' pro forma debt to capital ratio was 0.20:1.
 
FOREIGN OWNERSHIP
 
     The Certificate of Incorporation contains provisions that limit foreign
ownership of the stock of Noble. These provisions are to protect the ability of
Noble to continue to own its mobile offshore drilling units as U.S. flag vessels
and to comply with covenants of Noble to maintain U.S. citizenship (as defined)
that are contained in certain financing agreements.
 
                                       70
<PAGE>   83
 
     In order to continue to enjoy the benefits of U.S. flag registry for its
vessels, Noble must maintain "United States citizenship" as defined in the
Shipping Act, 1916, as amended (the "Shipping Act"). A corporation is not
considered a U.S. citizen for these purposes unless, among other things, the
controlling interest therein (a majority in the case of non-coastwise trade) is
owned by U.S. citizens. Under regulations adopted by the U.S. Maritime
Administration to implement the citizenship requirements, the "controlling
interest" test is applied to each class of stock of Noble. The Noble Common
Stock and all series of Noble's preferred stock combined are considered to be
separate classes of stock for this purpose.
 
     Under the provisions of the Certificate of Incorporation, (i) any transfer,
or attempted or purported transfer, of any shares of stock of Noble that would
result in the ownership or control by one or more persons who is not a U.S.
citizen for purposes of the Shipping Act of an aggregate percentage of the
shares of any class of stock in excess of a fixed percentage (the "Permitted
Percentage") that is equal to 90 percent of the percentage that would prevent
Noble from being a U.S. citizen (currently 50 percent) for purposes of the
Shipping Act, will, for so long as such excess shall exist, be void and
ineffective as against Noble, and (ii) if at any time ownership of shares of
stock of Noble (either of record or beneficial) by persons other than U.S.
citizens exceeds the Permitted Percentage, Noble may withhold payment of
dividends on such shares determined to be in excess of the Permitted Percentage
and may suspend voting rights attributable to such shares. The shares subject to
any such withholding of dividends or suspension of voting rights would be those
foreign-owned shares that the Board of Directors of Noble determines became so
owned most recently. The Permitted Percentage is currently 45 percent.
 
     Certificates representing the shares of Noble Common Stock and $1.50 Noble
Preferred Stock issued pursuant to the Merger Agreement will bear legends
concerning the restrictions on ownership by persons other than U.S. citizens.
Noble has instructed its transfer agent for the Noble Common Stock, the $2.25
Noble Preferred Stock and the $1.50 Noble Preferred Stock to attempt to ensure
the applicable transfer instructions are enforced.
 
CERTAIN CORPORATE GOVERNANCE PROVISIONS
 
     Stockholder Consent Action Prohibited. The Certificate of Incorporation and
Bylaws of Noble require that, subject to the possible rights of the holders of
any class or series of stock having a preference over the Noble Common Stock as
to dividends or upon liquidation, stockholder action be taken only at an annual
meeting or at a special meeting of stockholders called by the Chairman of the
Board or the President of Noble or by a majority of the entire Board of
Directors of Noble, and prohibit stockholder action by written consent in lieu
of a meeting. Stockholders are not permitted to call a special meeting of
stockholders or to require that the Board of Directors of Noble call such a
special meeting.
 
     Classified Board and Other Provisions. The Certificate of Incorporation and
Bylaws of Noble provide that, subject to the possible rights of the holders of
any class or series of stock having a preference over the Noble Common Stock as
to dividends or upon liquidation, the Board of Directors of Noble will be
composed of not less than three directors, with the exact number of directors
fixed from time to time by resolution adopted by vote of a majority of the
entire Board of Directors, and is divided into three classes of directors, each
class to be as nearly equal in number as possible. The term of office of one
class of directors expires each year in rotation so that one class is elected at
each annual meeting of stockholders for a full three-year term.
 
     The Certificate of Incorporation and Bylaws of Noble provide that a
director may be removed only for cause as defined in the Certificate of
Incorporation, and only by the affirmative vote of the holders of a majority of
the combined voting power of the Voting Stock.
 
     The Certificate of Incorporation of Noble provides that, subject to the
possible rights of the holders of any class or series of stock having a
preference over the Noble Common Stock as to dividends or upon liquidation, a
vacancy on the Board resulting from any increase in the number of directors may
be filled by the Board or in the manner provided in the Bylaws of Noble, that
any other vacancy shall be filled only by an affirmative vote of a majority of
directors remaining in office, even though less than a quorum, and that the
newly-elected director shall serve for the unexpired term of his predecessor in
office. The Bylaws provide that if any vacancy resulting from an increase in the
number of directors is not filled by the remaining directors it will be filled
by
 
                                       71
<PAGE>   84
 
the stockholders of Noble at the next annual meeting or at a special meeting of
stockholders called for that purpose.
 
     An anti-takeover effect is accomplished by these provisions in that they
tend to preclude a third party from removing incumbent directors and
simultaneously gaining control of the Board by filling the vacancies created by
removal with its own nominees unless such third party controls at least 80
percent of the combined voting power of the Voting Stock (the ownership level
required to amend Noble's Certificate Incorporation and Bylaws in this respect).
Under these provisions, together with the classified board provisions described
above, it would take at least two elections of directors for any individual or
group to gain control of the Noble Board.
 
     Fair Price Provision. The affirmative vote of the holders of at least 80
percent of the combined voting power of the Voting Stock is required to approve
certain Business Combinations (as such term is defined in the Certificate of
Incorporation). The transactions included in the definition of Business
Combination are those between Noble and an Interested Stockholder (as defined
below) or, in certain instances, proposed by an Interested Stockholder and
include: (i) a merger or consolidation of Noble, or any subsidiary having assets
of $1,000,000 or more, with any Interested Stockholder or with any other
corporation or entity that is, or after such merger or consolidation would be,
an affiliate or associate of an Interested Stockholder; (ii) the sale or other
disposition by Noble, or a subsidiary, of assets of $1,000,000 or more if an
Interested Stockholder (or an affiliate or associate thereof) is a party to the
transaction; (iii) the issuance or transfer of any securities of Noble, or a
subsidiary, to an Interested Stockholder (or an affiliate or associate thereof)
in exchange for cash, securities or other property (or a combination thereof) of
$1,000,000 or more; (iv) the adoption of any plan or proposal for the
liquidation or dissolution of Noble proposed by or on behalf of an Interested
Stockholder (or an affiliate or associate thereof); (v) any reclassification of
securities, recapitalization, merger with a subsidiary or other transaction that
has the effect, directly or indirectly, of increasing the proportionate share of
the outstanding shares (or securities convertible into shares) of any class or
series of stock of Noble or a subsidiary owned by an Interested Stockholder (or
an affiliate or associate thereof); (vi) any series or combination of
transactions directly or indirectly having the same effect as any of the
foregoing; or (vii) any contract, agreement or other arrangement providing
directly or indirectly for any of the foregoing. An "Interested Stockholder" is
defined in the Noble Certificate of Incorporation to include a beneficial owner
of five percent or more of the combined voting power of the Voting Stock, other
than Noble, and any affiliate of Noble who, at any time during the preceding two
years, was the beneficial owner of five percent or more of the combined voting
power of the Voting Stock and includes any person who is an assignee of or has
succeeded to any shares of Voting Stock in a transaction not involving a public
offering which were at any time within the prior two-year period beneficially
owned by an Interested Stockholder. The term "beneficial owner" includes persons
directly and indirectly owning or having the right to acquire or vote the stock
in question.
 
     The provisions of the Certificate of Incorporation of Noble described in
the preceding paragraph may have the effect of delaying, deterring or preventing
a change in control of Noble. The special vote requirement of such provisions
may be waived if the Business Combination is duly approved by a majority of the
Disinterested Directors (as such term is defined in the Certificate of
Incorporation of Noble) or if certain minimum price criteria and procedural
requirements are met. There is no requirement that a Business Combination duly
approved by the Disinterested Directors meet any minimum price criteria or
procedural requirements.
 
     Alteration or Amendment. The approval of the holders of 80 percent or more
of the combined voting power of the Voting Stock is required for the alteration,
amendment or repeal of, or the adoption of any provision inconsistent with, the
foregoing corporate governance provisions as stated in the Certificate of
Incorporation of Noble. In addition, the affirmative vote of a majority of the
entire Board may authorize the alteration, amendment or repeal of the Bylaws of
Noble.
 
     Elimination of Certain Director Liability; Indemnification. The Noble
Certificate of Incorporation contains an article, which was approved by
stockholders at the 1987 annual meeting of stockholders, that eliminates the
personal liability of Noble's directors for monetary damages resulting from
breaches of their fiduciary duty, to the extent permitted by the DGCL. This
article eliminates the liability of each director to
 
                                       72
<PAGE>   85
 
Noble or its stockholders for all claims for negligence or gross negligence in
the performance of his duties other than the duty of loyalty. Directors remain
liable to Noble and its stockholders for breaches of their duty of loyalty, as
well as for acts or omissions not in good faith or which involve intentional
misconduct or a knowing violation of law, and for transactions from which a
director derives improper personal benefit. The article does not limit the
liability of directors under Section 174 of the DGCL, which makes directors
personally liable for unlawful dividends or unlawful stock repurchases or
redemptions and expressly sets forth a negligence standard with respect to such
liability.
 
     The Noble Certificate of Incorporation and the Bylaws of Noble contain
provisions providing for the indemnification of Noble's directors and officers
to the fullest extent permitted by Section 145 of the DGCL, including in
circumstances in which indemnification is otherwise discretionary.
 
     Noble believes that these provisions are necessary to attract and retain
qualified persons as directors and officers.
 
     The Delaware Business Combination Act. Noble is covered by Section 203 of
the DGCL which provides that a corporation shall not engage in any business
combination with an "interested stockholder" for a period of three years
following the date that such stockholder became an interested stockholder
unless: (i) prior to such date, the board of directors of the corporation
approved either the business combination or the transaction that resulted in the
stockholder becoming an interested stockholder, (ii) upon consummation of such
transaction, the interested stockholder owned at least 85 percent of the voting
stock of the corporation outstanding at the time (excluding, from the
calculation of outstanding shares, shares beneficially owned by management,
directors and certain employee stock plans), or (iii) on or after such date, the
business combination is (A) approved by the board of directors and (B)
authorized at a meeting of stockholders by the affirmative vote of the holders
of at least two-thirds of the outstanding voting stock other than the interested
stockholder.
 
                        COMPARISON OF STOCKHOLDER RIGHTS
 
     If the Merger is consummated, the stockholders of Chiles will become
stockholders of Noble. The rights of the stockholders of both Noble and Chiles
are governed by and subject to the provisions of the DGCL. The rights of current
Chiles stockholders following the Merger will be governed by the Noble
Certificate of Incorporation and the Noble Bylaws rather than the provisions of
the Certificate of Incorporation and Bylaws of Chiles. The following is a brief
summary of certain differences between the rights of stockholders of Noble and
the rights of stockholders of Chiles and is qualified in its entirety by
reference to the relevant provisions of the DGCL, the Noble Certificate of
Incorporation, the Noble Bylaws, Chiles' Certificate of Incorporation (the
"Chiles Certificate of Incorporation") and Chiles' Bylaws.
 
GENERAL
 
     Chiles, like Noble, is a Delaware corporation organized under the DGCL.
Both the Noble Certificate of Incorporation and the Chiles Certificate of
Incorporation deny preemptive rights, and neither permits cumulative voting.
Whereas Noble has a classified Board of Directors, Chiles does not. Although
Noble does not allow its stockholders to take action by written consent, Chiles
does. The Chiles Certificate of Incorporation does not contain provisions
requiring a supermajority vote under any circumstances and does not include a
fair price provision.
 
AUTHORIZED CAPITAL
 
     Noble has 90,000,000 authorized shares of stock, consisting of (i)
75,000,000 shares of Noble Common Stock and (ii) 15,000,000 shares of preferred
stock having a par value of $1.00 per share. There is one series of preferred
stock designated, of which there are 2,990,000 shares of $2.25 Noble Preferred
Stock outstanding. If the Noble Charter Amendment is effected, Noble will have
215,000,000 authorized shares of stock, consisting of (i) 200,000,000 shares of
Noble Common Stock and (ii) 15,000,000 shares of preferred stock. If the
 
                                       73
<PAGE>   86
 
Merger is consummated, up to 4,025,000 shares of a new series of preferred stock
will be issued in the Merger as the $1.50 Noble Preferred Stock.
 
     Chiles has the authority to issue 110,000,000 shares of capital stock,
100,000,000 of which are Chiles Common Stock and 10,000,000 are preferred stock,
par value $1.00 per share. Chiles has designated 4,025,000 shares of the
preferred stock as $1.50 Convertible Preferred Stock, all of which shares were
outstanding as of the date hereof.
 
REMOVAL OF DIRECTORS
 
     A director of Noble may be removed from office only for cause and only by
the affirmative vote of the holders of a majority of the combined voting power
of the then outstanding shares of Voting Stock, voting together as a single
class. For this purpose, "cause" means the willful and continuous failure of a
director substantially to perform such director's duties to Noble (other than
any such failure resulting from incapacity due to physical or mental illness) or
the willful engaging by a director in gross misconduct materially and
demonstrably injurious to Noble. In accordance with Section 141(k) of the DGCL,
a director of Chiles may be removed, with or without cause, by the holders of a
majority of the shares then entitled to vote at an election of directors.
 
POWER OF STOCKHOLDERS TO CALL SPECIAL MEETING
 
     The Noble Certificate of Incorporation and Noble Bylaws do not provide the
stockholders the right to call a special meeting. A special meeting of Chiles
stockholders may be called by 10 percent of the holders of the shares then
outstanding and entitled to vote.
 
CLASSIFIED BOARD AND FAIR PRICE PROVISION
 
     Classified Board. As discussed above, Noble's Board of Directors is divided
into three classes. Chiles does not have a classified Board of Directors.
Noble's classified Board and the possible anti-takeover effects of
classification are described above. See "Description of Noble Capital
Stock -- Certain Corporate Governance Provisions."
 
     Fair Price Provision. As discussed above, the Noble Certificate of
Incorporation contains a fair price provision. The Chiles Certificate of
Incorporation does not contain such a provision. The fair price provision and
its possible anti-takeover effects are described above. See "Description of
Noble Capital Stock -- Certain Corporate Governance Provisions."
 
     Alteration or Amendment. The approval of the holders of 80 percent or more
of the combined voting power of the Voting Stock of Noble is required for the
alteration, amendment or repeal of, or the adoption of any provision
inconsistent with, the foregoing corporate governance provisions as stated in
the Noble Certificate of Incorporation. The Noble Board of Directors may
authorize the alteration, amendment or repeal of the Noble Bylaws.
 
                        MANAGEMENT AND OTHER INFORMATION
 
     Certain information relating to the management, executive compensation,
voting securities and the principal holders thereof, certain relationships and
related transactions and other related matters pertaining to Noble and Chiles is
set forth in or incorporated by reference in their respective Annual Reports on
Form 10-K for the year ended December 31, 1993. Such Annual Reports are
incorporated in this Joint Proxy Statement/Prospectus. See "Incorporation of
Certain Documents by Reference." Stockholders who wish to obtain copies of these
documents may contact Noble or Chiles at their respective addresses or telephone
numbers as set forth under "Incorporation of Certain Documents by Reference."
 
                                       74
<PAGE>   87
 
                                 LEGAL MATTERS
 
     The validity of the shares of Noble Common Stock and $1.50 Noble Preferred
Stock offered by this Joint Proxy Statement/Prospectus will be passed upon for
Noble by Thompson & Knight, A Professional Corporation, Dallas, Texas.
 
                                    EXPERTS
 
     The audited consolidated financial statements and schedules of Noble
incorporated by reference in this Joint Proxy Statement/Prospectus have been
audited by Arthur Andersen & Co., independent public accountants, as indicated
in their report with respect thereto, and are so incorporated in reliance upon
the authority of said firm as experts in giving said report.
 
     The audited consolidated financial statements and schedules of Chiles
incorporated by reference in this Joint Proxy Statement/Prospectus have been
audited by Arthur Andersen & Co., independent public accountants, as indicated
in their report with respect thereto, and are so incorporated in reliance upon
the authority of said firm as experts in giving said report.
 
     The consolidated financial statements of Triton and subsidiaries as of
December 31, 1993 and 1992, and for each of the years in the two-year period
ended December 31, 1993, have been incorporated by reference herein and in the
registration statement in reliance upon the report of KPMG Peat Marwick,
independent certified public accountants, incorporated by reference herein, and
upon the authority of said firm as experts in accounting and auditing.
 
                             STOCKHOLDER PROPOSALS
 
     Stockholder proposals for inclusion in Noble's proxy materials in
connection with the 1995 annual meeting of stockholders must be received by
Noble at its offices in Houston, Texas, addressed to Ms. Julie J. Robertson,
Secretary, no later than November 28, 1994.
 
     If the Merger is not consummated, the annual meeting of the stockholders of
Chiles is expected to be held in May 1995. Any proposals of the stockholders of
Chiles intended to be presented at the annual meeting must be received by
Chiles, addressed to the Secretary, no later than December 20, 1995, to be
considered for inclusion in the proxy statement and form of proxy relating to
that meeting.
 
                                       75
<PAGE>   88
 
                                                                      APPENDIX I
 
                          AGREEMENT AND PLAN OF MERGER
                                     AMONG
                          NOBLE DRILLING CORPORATION,
                           NOBLE OFFSHORE CORPORATION
                                      AND
                          CHILES OFFSHORE CORPORATION
 
                                 JUNE 13, 1994
<PAGE>   89
 
                               TABLE OF CONTENTS
 
                                   ARTICLE I
 
                                   THE MERGER
 
<TABLE>
<S>   <C>                                                                                  <C>
1.1   The Merger.........................................................................     1
1.2   Closing Date.......................................................................     1
1.3   Consummation of the Merger.........................................................     1
1.4   Effects of the Merger..............................................................     2
1.5   Certificate of Incorporation; Bylaws...............................................     2
1.6   Directors and Officers.............................................................     2
1.7   Conversion of Securities...........................................................     2
1.8   Exchange of Certificates; Fractional Shares........................................     2
1.9   Taking of Necessary Action; Further Action.........................................     3

                                          ARTICLE II
                                REPRESENTATIONS AND WARRANTIES
2.1   Representations and Warranties of Noble and Sub....................................     4
2.2   Representations and Warranties of Chiles...........................................    11

                                          ARTICLE III
                        COVENANTS OF CHILES PRIOR TO THE EFFECTIVE TIME
3.1   Conduct of Business by Chiles Pending the Merger...................................    16
3.2   Joint Proxy Statement..............................................................    17
3.3   Meeting of Stockholders of Chiles..................................................    18
3.4   No Shopping........................................................................    18
3.5   Affiliates' Agreements.............................................................    19

                                          ARTICLE IV
                        COVENANTS OF NOBLE PRIOR TO THE EFFECTIVE TIME
4.1   Conduct of Business by Noble Pending the Merger....................................    19
4.2   Joint Proxy Statement..............................................................    20
4.3   Meeting of Stockholders of Noble...................................................    20
4.4   Registration Statement.............................................................    20
4.5   Reservation of Noble Stock.........................................................    21
4.6   Stock Exchange Listing.............................................................    21
4.7   Affiliates' Agreements.............................................................    21
4.8   Registration Rights Agreement......................................................    21

                                           ARTICLE V
                                     ADDITIONAL AGREEMENTS
5.1   Accountants Letters................................................................    21
5.2   Filings; Consents; Reasonable Efforts..............................................    21
5.3   Notification of Certain Matters....................................................    21
5.4   Agreement to Defend................................................................    21
5.5   Expenses...........................................................................    22
5.6   Noble's Board of Directors.........................................................    22
5.7   Indemnification....................................................................    22
</TABLE>
 
                                        i
<PAGE>   90
 
<TABLE>
<S>   <C>                                                                                  <C>
5.8   Chiles Employee Benefits...........................................................    23
5.9   Post-Effective Time Mailing........................................................    23
5.10  Tax Opinion........................................................................    23
5.11  Chiles Stock Options...............................................................    23
5.12  Designation of $1.50 Noble Preferred Stock.........................................    24

                                          ARTICLE VI
                                          CONDITIONS
6.1   Conditions to Obligation of Each Party to Effect the Merger........................    24
6.2   Additional Conditions to Obligations of Noble......................................    25
6.3   Additional Conditions to Obligations of Chiles.....................................    26

                                          ARTICLE VII
                                         MISCELLANEOUS
7.1   Termination........................................................................    27
7.2   Effect of Termination..............................................................    27
7.3   Waiver and Amendment...............................................................    28
7.4   Nonsurvival of Representations, Warranties and Agreements..........................    28
7.5   Public Statements..................................................................    28
7.6   Assignment.........................................................................    28
7.7   Notices............................................................................    29
7.8   Governing Law......................................................................    29
7.9   Severability.......................................................................    29
7.10  Counterparts.......................................................................    29
7.11  Headings...........................................................................    29
7.12  Confidentiality Agreements.........................................................    29
7.13  Entire Agreement; Third Party Beneficiaries........................................    29
7.14  Disclosure Letters.................................................................    29
7.15  Stock Exchange.....................................................................    30
</TABLE>
 
                                       ii
<PAGE>   91
 
                          AGREEMENT AND PLAN OF MERGER
 
     This Agreement and Plan of Merger, dated as of the 13th day of June, 1994
(the "Agreement"), is among Noble Drilling Corporation, a Delaware corporation
("Noble"), Noble Offshore Corporation, a newly-formed Delaware corporation and a
wholly-owned subsidiary of Noble ("Sub"), and Chiles Offshore Corporation, a
Delaware corporation ("Chiles").
 
     WHEREAS, subject to and in accordance with the terms and conditions of this
Agreement, the respective Boards of Directors of Noble, Sub and Chiles, and
Noble as sole stockholder of Sub, have approved the merger of Chiles with and
into Sub (the "Merger"), whereby (i) each issued and outstanding share of common
stock, par value $.01 per share, of Chiles ("Chiles Common Stock") not owned
directly or indirectly by Chiles will be converted into the right to receive
shares of common stock, par value $.10 per share, of Noble ("Noble Common
Stock") and (ii) each issued and outstanding share of $1.50 Convertible
Preferred Stock, par value $1.00 per share, of Chiles ("Chiles Preferred Stock")
not owned directly or indirectly by Chiles will be converted into the right to
receive shares of a new series of $1.50 Convertible Preferred Stock of Noble
("$1.50 Noble Preferred Stock") having substantially equivalent rights and
preferences to the Chiles Preferred Stock, as provided herein;
 
     WHEREAS, for federal income tax purposes, it is intended that the Merger
shall qualify as a reorganization within the meaning of Section 368(a) of the
Internal Revenue Code of 1986, as amended (the "Code");
 
     WHEREAS, the Merger is intended to be treated as a "pooling of interests"
for accounting purposes; and
 
     WHEREAS, the parties hereto desire to set forth certain representations,
warranties and covenants made by each to the other as an inducement to the
consummation of the Merger;
 
     NOW, THEREFORE, in consideration of the premises and of the mutual
representations, warranties and covenants herein contained, the parties hereto
hereby agree as follows:
 
                                   ARTICLE I
 
                                   THE MERGER
 
     1.1 The Merger. Subject to and in accordance with the terms and conditions
of this Agreement and in accordance with the General Corporation Law of the
State of Delaware (the "DGCL"), at the Effective Time (as defined in Section
1.3) Chiles shall be merged with and into Sub. As a result of the Merger, the
separate corporate existence of Chiles shall cease and Sub shall continue as the
surviving corporation (sometimes referred to herein as the "Surviving
Corporation"), and all the properties, rights, privileges, powers and franchises
of Chiles and Sub shall vest in the Surviving Corporation, without any transfer
or assignment having occurred, and all debts, liabilities and duties of Chiles
and Sub shall attach to the Surviving Corporation, all in accordance with the
DGCL.
 
     1.2 Closing Date. The closing of the transactions contemplated by this
Agreement (the "Closing") shall take place at the offices of Thompson & Knight,
P.C., 1700 Texas Commerce Tower, 600 Travis, Houston, Texas 77002, as soon as
practicable after the satisfaction or waiver of the conditions set forth in
Article VI or at such other time and place and on such other date as Noble and
Chiles shall agree; provided, that the closing conditions set forth in Article
VI shall have been satisfied or waived at or prior to such time. The date on
which the Closing occurs is herein referred to as the "Closing Date".
 
     1.3 Consummation of the Merger. As soon as practicable on the Closing Date,
the parties hereto will cause the Merger to be consummated by filing with the
Secretary of State of Delaware a certificate of merger in such form as required
by, and executed in accordance with, the relevant provisions of the DGCL. The
"Effective Time" of the Merger as that term is used in this Agreement shall mean
such time as the certificate of merger is duly filed with the Secretary of State
of Delaware or at such later time (not to exceed 90 days from the date the
certificate is filed) as is specified in the certificate of merger pursuant to
the mutual agreement of Noble and Chiles.
 
                                        1
<PAGE>   92
 
     1.4 Effects of the Merger. The Merger shall have the effects set forth in
the applicable provisions of the DGCL.
 
     1.5 Certificate of Incorporation; Bylaws. The Certificate of Incorporation
of Chiles, as in effect immediately prior to the Effective Time, shall be
amended as of the Effective Time so that Article 1 thereof reads in its
entirety: "The name of the corporation is Noble Offshore Corporation" and, as so
amended, such Certificate of Incorporation shall be the Certificate of
Incorporation of the Surviving Corporation and thereafter shall continue to be
its Certificate of Incorporation until amended as provided therein and under the
DGCL. The bylaws of Sub, as in effect immediately prior to the Effective Time,
shall be the bylaws of the Surviving Corporation and thereafter shall continue
to be its bylaws until amended as provided therein and under the DGCL.
 
     1.6 Directors and Officers. The directors of Sub immediately prior to the
Effective Time shall be the directors of the Surviving Corporation at and after
the Effective Time, each to hold office in accordance with the Certificate of
Incorporation and bylaws of the Surviving Corporation, and the officers of Sub
immediately prior to the Effective Time shall be the officers of the Surviving
Corporation at and after the Effective Time, in each case until their respective
successors are duly elected or appointed and qualified.
 
     1.7 Conversion of Securities. Subject to the terms and conditions of this
Agreement, at the Effective Time, by virtue of the Merger and without any action
on the part of Noble, Chiles, Sub or their stockholders:
 
          (a) Each share of Chiles Common Stock issued and outstanding
     immediately prior to the Effective Time, other than any shares of Chiles
     Common Stock to be cancelled pursuant to Section 1.7(c), shall be converted
     into the right to receive 0.75 of a share of Noble Common Stock; provided,
     however, that no fractional shares of Noble Common Stock shall be issued,
     and, in lieu thereof, a cash payment shall be made in accordance with
     Section 1.8(d) hereof.
 
          (b) Each share of Chiles Preferred Stock (together with the shares of
     Chiles Common Stock issued and outstanding immediately prior to the
     Effective Time, the "Shares") issued and outstanding immediately prior to
     the Effective Time, other than any shares of Chiles Preferred Stock to be
     cancelled pursuant to Section 1.7(c), shall be converted into the right to
     receive one share of $1.50 Noble Preferred Stock.
 
          (c) Each Share held in the treasury of Chiles and each Share owned by
     Sub, Noble or any direct or indirect wholly-owned subsidiary of Noble or of
     Chiles immediately prior to the Effective Time shall be cancelled and
     extinguished without any conversion thereof and no payment shall be made
     with respect thereto.
 
          (d) Each share of common stock, par value $.01 per share, of Sub
     issued and outstanding immediately prior to the Effective Time shall be
     converted into one share of common stock, $.01 par value per share, of the
     Surviving Corporation.
 
1.8 Exchange of Certificates; Fractional Shares.
 
          (a) As soon as practicable after the Effective Time, each holder of a
     certificate that prior thereto represented Shares shall be entitled, upon
     surrender thereof to Noble or its transfer agent, to receive in exchange
     therefor, as applicable (i) a certificate or certificates representing the
     number of whole shares of Noble Common Stock into which the shares of
     Chiles Common Stock so surrendered shall have been converted as aforesaid,
     in such denominations and registered in such names as such holder may
     request or (ii) a certificate or certificates representing the number of
     shares of $1.50 Noble Preferred Stock into which the shares of Chiles
     Preferred Stock so surrendered shall have been converted as aforesaid, in
     such denominations and registered in such names as such holder may request.
     Each holder of shares of Chiles Common Stock who would otherwise be
     entitled to a fraction of a share of Noble Common Stock shall, upon
     surrender of the certificates representing such shares held by such holder
     to Noble or its transfer agent, be paid an amount in cash in accordance
     with the provisions of Section 1.8(d). Until so surrendered and exchanged,
     each certificate that prior to the Effective Time represented Shares shall
     represent solely the right to receive Noble Common Stock and cash in lieu
     of fractional shares, if any, or
 
                                        2
<PAGE>   93
 
     $1.50 Noble Preferred Stock, as the case may be. Unless and until any
     such certificates shall be so surrendered and exchanged, no dividends
     or other distributions payable to the holders of Noble Common Stock or
     $1.50 Noble Preferred Stock, as of any time on or after the Effective
     Time, shall be paid to the holders of such certificates that prior to
     the Effective Time represented Shares; provided, however, that, upon
     any such surrender and exchange of such certificates, there shall be
     paid to the record holders of the certificates issued and exchanged
     therefor the amount, without interest thereon, of dividends and other
     distributions, if any, that theretofore were declared and became
     payable after the Effective Time with respect to the number of whole
     shares of Noble Common Stock or $1.50 Noble Preferred Stock, as the
     case may be, issued to such holder.
 
          (b) All shares of Noble Common Stock and $1.50 Noble Preferred Stock
     issued upon the surrender for exchange of certificates that prior to the
     Effective Time represented Shares in accordance with the terms hereof
     (including any cash paid pursuant to Section 1.8(d)) shall be deemed to
     have been issued in full satisfaction of all rights pertaining to such
     Shares. At and after the Effective Time, there shall be no further
     registration of transfers on the stock transfer books of the Surviving
     Corporation of the Shares that were outstanding immediately prior to the
     Effective Time. If, after the Effective Time, certificates which prior to
     the Effective Time represented Shares are presented to the Surviving
     Corporation for any reason, they shall be cancelled and exchanged as
     provided in this Article I.
 
          (c) If any certificate for shares of Noble Common Stock or $1.50 Noble
     Preferred Stock is to be issued in a name other than that in which the
     certificate surrendered in exchange therefor is registered, it shall be a
     condition of the issuance thereof that the certificate so surrendered shall
     be properly endorsed and otherwise in proper form for transfer and that the
     person requesting such exchange shall have paid to Noble or its transfer
     agent any transfer or other taxes required by reason of the issuance of a
     certificate for shares of Noble Common Stock or $1.50 Noble Preferred Stock
     in any name other than that of the registered holder of the certificate
     surrendered, or established to the satisfaction of Noble or its transfer
     agent that such tax has been paid or is not payable.
 
          (d) No fraction of a share of Noble Common Stock shall be issued, but
     in lieu thereof each holder of Chiles Common Stock who would otherwise be
     entitled to a fraction of a share of Noble Common Stock shall, upon
     surrender of the certificate formerly representing Chiles Common Stock held
     by such holder to Noble or its transfer agent, be paid an amount in cash
     equal to the value of such fraction of a share based upon the closing sales
     price of Noble Common Stock, as reported on the NASDAQ National Market
     System, on the last day on which there is a reported trade in the Noble
     Common Stock prior to the date on which the Effective Time occurs. No
     interest shall be paid on such amount. All shares of Chiles Common Stock
     held by a record holder shall be aggregated for purposes of computing the
     number of shares of Noble Common Stock to be issued pursuant to this
     Article I and cash in lieu of fractional shares payable hereunder.
 
          (e) None of Noble, Sub, Chiles, the Surviving Corporation or their
     transfer agents shall be liable to a holder of the Shares for any amount
     properly paid to a public official pursuant to applicable property, escheat
     or similar laws.
 
     1.9 Taking of Necessary Action; Further Action. The parties hereto shall
take all such reasonable and lawful action as may be necessary or appropriate in
order to effectuate the Merger as promptly as possible. If, at any time after
the Effective Time, any such further action is necessary or desirable to carry
out the purposes of this Agreement and to vest the Surviving Corporation with
full right, title and possession to all assets, property, rights, privileges,
powers and franchises of Chiles or Sub, such corporations shall direct their
respective officers and directors to take all such lawful and necessary action.
 
                                        3
<PAGE>   94
 
                                   ARTICLE II
 
                         REPRESENTATIONS AND WARRANTIES
 
     2.1 Representations and Warranties of Noble and Sub. Noble and Sub hereby
jointly and severally represent and warrant to Chiles that:
 
          (a) Organization and Compliance with Law. Each of Noble and its
     consolidated subsidiaries (the "Noble Subsidiaries") is a corporation duly
     organized, validly existing and in good standing under the laws of the
     jurisdiction in which it is chartered or organized and has all requisite
     corporate power and corporate authority and all necessary governmental
     authorizations to own, lease and operate all of its properties and assets
     and to carry on its business as now being conducted, except where the
     failure to be so organized, existing or in good standing or to have such
     governmental authority would not have a material adverse effect on the
     financial condition, results of operations or business of Noble and the
     Noble Subsidiaries, taken as a whole. Except as set forth in Section 2.1(a)
     of the disclosure letter delivered by Noble to Chiles on the date hereof
     (the "Noble Disclosure Letter"), each of Noble and the Noble Subsidiaries
     is duly qualified as a foreign corporation to do business, and is in good
     standing, in each jurisdiction in which the property owned, leased or
     operated by it or the nature of the business conducted by it makes such
     qualification necessary, except in such jurisdictions where the failure to
     be duly qualified does not and would not, either individually or in the
     aggregate, have a material adverse effect on the financial condition,
     results of operations or business of Noble and the Noble Subsidiaries,
     taken as a whole. Each of Noble and the Noble Subsidiaries is in compliance
     with all applicable laws, judgments, orders, rules and regulations,
     domestic and foreign, except where failure to be in such compliance would
     not have a material adverse effect on the financial condition, results of
     operations or business of Noble and the Noble Subsidiaries, taken as a
     whole. Noble has heretofore delivered to Chiles true and complete copies of
     Noble's Restated Certificate of Incorporation (the "Noble Certificate") and
     bylaws as in existence on the date hereof.
 
     (b) Capitalization.
 
             (i) The authorized capital stock of Noble consists of 75,000,000
        shares of Noble Common Stock, par value $.10 per share, and 15,000,000
        shares of preferred stock, par value $1.00 per share (subject to an
        amendment (the "Noble Charter Amendment") to the Noble Certificate to
        increase the authorized shares of Noble Common Stock to 200,000,000
        shares to be proposed in connection with the Merger). As of May 31,
        1994, there were issued and outstanding 48,390,873 shares of Noble
        Common Stock and 2,990,000 shares of $2.25 Convertible Exchangeable
        Preferred Stock (the "$2.25 Noble Preferred Stock"), and 250,000 shares
        of Noble Common Stock and no shares of $2.25 Noble Preferred Stock were
        held as treasury shares. As of May 31, 1994, (A) an aggregate of
        19,755,352 shares of Noble Common Stock were reserved (subject, in the
        case of the 1991 Stock Option and Restricted Stock Plan, to an amendment
        to such plan to be proposed to increase the number of shares of Noble
        Common Stock subject thereto) for issuance and issuable pursuant to
        Noble's Thrift Plan, Field Hourly Employees' Retirement Plan and Noble
        (International) Employees' Retirement Savings Plan or upon the exercise
        of outstanding employee or non-employee director stock options granted
        under Noble's stock option plans and agreements or the conversion of the
        $2.25 Noble Preferred Stock, and (B) an indeterminable number of shares
        of Noble Common Stock (of up to at least 254,551 shares) were reserved
        for issuance pursuant to that certain Stock Purchase Agreement dated
        April 22, 1994 among Noble, Triton Engineering Services Company, Joseph
        E. Beall and George H. Bruce (the "Triton Agreement"). All issued shares
        of Noble Common Stock and $2.25 Noble Preferred Stock are validly
        issued, fully paid and nonassessable and no holder thereof is entitled
        to preemptive rights. All shares of Noble Common Stock and $1.50 Noble
        Preferred Stock to be issued pursuant to the Merger, when issued in
        accordance with this Agreement, will be validly issued, fully paid and
        nonassessable and will not violate the preemptive rights of any person.
        Except as set forth in Section 2.1(b) of the Noble Disclosure Letter,
        Noble is not a party to, and is not aware of, any voting agreement,
        voting trust or similar agreement or
 
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<PAGE>   95
 
        arrangement relating to any class or series of its capital stock, or
        any agreement or arrangement providing for registration rights with
        respect to any capital stock or other securities of Noble.
 
             (ii) As of May 31, 1994, there were outstanding options to purchase
        2,095,775 shares of Noble Common Stock pursuant to the plans and
        agreements referenced in Section 2.1(b)(i) above (the "Noble Options").
        Other than as set forth in this Section 2.1(b) and except for issuances
        contemplated by this Agreement in connection with the Merger and by the
        Triton Agreement, there are not now, and at the Effective Time there
        will not be, any (A) shares of capital stock or other equity securities
        of Noble outstanding (other than Noble Common Stock issued pursuant to
        the exercise of Noble Options as described herein or upon the conversion
        of any convertible securities of Noble outstanding on the date hereof)
        or (B) outstanding options, warrants, scrip, rights to subscribe for,
        calls or commitments of any character whatsoever relating to, or
        securities or rights convertible into or exchangeable for, shares of any
        class of capital stock of Noble, or contracts, understandings or
        arrangements to which Noble is a party, or by which it is or may be
        bound, to issue additional shares of its capital stock or options,
        warrants, scrip or rights to subscribe for, or securities or rights
        convertible into or exchangeable for, any additional shares of its
        capital stock.
 
             (iii) Except as set forth in Section 2.1(b) of the Noble Disclosure
        Letter, all outstanding shares of capital stock of the Noble
        Subsidiaries are owned by Noble, a wholly-owned subsidiary of Noble or
        individuals who hold nominal quantities of shares on behalf of Noble or
        such a subsidiary as director's qualifying shares, free and clear of all
        liens, charges, encumbrances, adverse claims and options of any nature
        which are material to Noble and the Noble Subsidiaries, taken as a
        whole.
 
             (iv) As of the date hereof, the authorized capital stock of Sub
        consists of 1,000 shares of common stock, par value $.01 per share, all
        of which are validly issued, fully paid and nonassessable and are owned
        by Noble.
 
          (c) Authorization and Validity of Agreement. Noble and Sub have all
     requisite corporate power and authority to enter into this Agreement and to
     perform their obligations hereunder. The execution and delivery by Noble
     and Sub of this Agreement and the consummation by each of them of the
     transactions contemplated hereby have been duly authorized by all necessary
     corporate action (subject only, with respect to the Merger, to the adoption
     of the Noble Charter Amendment and the approval of this Agreement by the
     stockholders of Noble as provided for in Section 4.3). On or prior to the
     date hereof, the Board of Directors of Noble has determined to recommend
     the adoption of the Noble Charter Amendment and the approval of the Merger
     to the stockholders of Noble, and such determination is in effect as of the
     date hereof. This Agreement has been duly executed and delivered by Noble
     and Sub and is the valid and binding obligation of Noble and Sub,
     enforceable against Noble and Sub in accordance with its terms.
 
          (d) No Approvals or Notices Required; No Conflict with Instruments to
     which Noble or any of the Noble Subsidiaries is a Party. Neither the
     execution and delivery of this Agreement nor the performance by Noble or
     Sub of its obligations hereunder, nor the consummation of the transactions
     contemplated hereby by Noble and Sub, will (i) conflict with the Noble
     Certificate or the bylaws of Noble or the charter or bylaws of any of the
     Noble Subsidiaries; (ii) assuming satisfaction of the requirements set
     forth in clause (iii) below, violate any provision of law applicable to
     Noble or any of the Noble Subsidiaries; (iii) except for (A) requirements
     of Federal or state securities laws, (B) requirements arising out of the
     Hart-Scott-Rodino Antitrust Improvements Act of 1976 (the "HSR Act"), (C)
     requirements of notice filings in such foreign jurisdictions as may be
     applicable, and (D) the filing of a certificate of merger by Sub in
     accordance with the DGCL, require any consent or approval of, or filing
     with or notice to, any public body or authority, domestic or foreign, under
     any provision of law applicable to Noble or any of the Noble Subsidiaries;
     or (iv) require any consent, approval or notice under, or violate, breach,
     be in conflict with or constitute a default (or an event that, with notice
     or lapse of time or both, would constitute a default) under, or permit the
     termination of any provision of, or result in the creation or imposition of
     any lien upon any properties, assets or business of Noble or any of the
     Noble Subsidiaries under, any note, bond, indenture, mortgage, deed of
     trust, lease, franchise, permit,
 
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<PAGE>   96
 
      authorization, license, contract, instrument or other agreement or
      commitment or any order, judgment or decree to which Noble or any of
      the Noble Subsidiaries is a party or by which Noble or any of the Noble
      Subsidiaries or any of its or their assets or properties is bound or
      encumbered, except (A) those that have already been given, obtained or
      filed, (B) those that are required pursuant to bank loan agreements, as
      set forth in Section 2.1(d) of the Noble Disclosure Letter, which will
      be obtained prior to the Effective Time, and (C) those that, in the
      aggregate, would not have a material adverse effect on the financial
      condition, results of operations or business of Noble and the Noble
      Subsidiaries, taken as a whole.
 
          (e) Commission Filings; Financial Statements. Noble and each of the
     Noble Subsidiaries have filed all reports, registration statements and
     other filings, together with any amendments required to be made with
     respect thereto, that they have been required to file with the Securities
     and Exchange Commission (the "Commission") under the Securities Act of
     1933, as amended (the "Securities Act"), and the Securities Exchange Act of
     1934, as amended (the "Exchange Act"). All reports, registration statements
     and other filings (including all notes, exhibits and schedules thereto and
     documents incorporated by reference therein) filed by Noble with the
     Commission since January 1, 1992, through the date of this Agreement,
     together with any amendments thereto, are sometimes collectively referred
     to as the "Noble Commission Filings". Noble has heretofore delivered to
     Chiles copies of the Noble Commission Filings. As of the respective dates
     of their filing with the Commission, the Noble Commission Filings complied
     in all material respects with the Securities Act, the Exchange Act and the
     rules and regulations of the Commission thereunder, and did not contain any
     untrue statement of a material fact or omit to state a material fact
     required to be stated therein or necessary to make the statements made
     therein, in light of the circumstances under which they were made, not
     misleading.
 
          All material contracts of Noble and the Noble Subsidiaries have been
     included in the Noble Commission Filings, except for those contracts not
     required to be filed pursuant to the rules and regulations of the
     Commission.
 
          Each of the consolidated financial statements (including any related
     notes or schedules) included in the Noble Commission Filings was prepared
     in accordance with generally accepted accounting principles applied on a
     consistent basis (except as may be noted therein or in the notes or
     schedules thereto) and complied with all applicable rules and regulations
     of the Commission. Such consolidated financial statements fairly present
     the consolidated financial position of Noble and the Noble Subsidiaries as
     of the dates thereof and the results of operations, cash flows and changes
     in shareholders' equity for the periods then ended (subject, in the case of
     the unaudited interim financial statements, to normal year-end audit
     adjustments on a basis comparable with past periods). As of the date
     hereof, Noble has no liabilities, absolute or contingent, that may
     reasonably be expected to have a material adverse effect on the financial
     condition, results of operations or business of Noble and the Noble
     Subsidiaries, taken as a whole, that are not reflected in the Noble
     Commission Filings, except (i) those incurred in the ordinary course of
     business consistent with past operations and not relating to the borrowing
     of money, and (ii) those set forth in Section 2.1 (e) of the Noble
     Disclosure Letter.
 
          (f) Conduct of Business in the Ordinary Course; Absence of Certain
     Changes and Events. Since January 1, 1994, except as contemplated by this
     Agreement or as disclosed in the Noble Commission Filings filed with the
     Commission prior to the date hereof or as set forth in Section 2.1(f) of
     the Noble Disclosure Letter, Noble and the Noble Subsidiaries have
     conducted their business only in the ordinary and usual course, and there
     has not been (i) any material adverse change in the financial condition,
     results of operations or business of Noble and the Noble Subsidiaries,
     taken as a whole, or any condition, event or development that reasonably
     may be expected to result in any such material adverse change; (ii) any
     material change by Noble in its accounting methods, principles or
     practices; (iii) any revaluation by Noble or any of the Noble Subsidiaries
     of any of its or their assets, including, without limitation, writing down
     the value of inventory or writing off notes or accounts receivable other
     than in the ordinary course of business; (iv) any entry by Noble or any of
     the Noble Subsidiaries into any commitment or transaction material to Noble
     and the Noble Subsidiaries, taken as a whole; (v) any declaration, setting
     aside or payment of any dividends or distributions in respect of the Noble
     Common Stock, or any redemption, purchase or other acquisition of any of
     its securities or any securities of any of the Noble
 
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<PAGE>   97
 
     Subsidiaries; (vi) any damage, destruction or loss (whether or not
     covered by insurance) materially adversely affecting the properties or
     business of Noble and the Noble Subsidiaries, taken as a whole; (vii)
     any increase in indebtedness for borrowed money other than borrowings
     under existing credit facilities; (viii) any granting of a security
     interest or lien on any material property or assets of Noble and the
     Noble Subsidiaries, taken as a whole, other than (A) liens for taxes
     not due and payable or which are being contested in good faith; (B)
     maritime liens and mechanics', warehousemen's and other statutory liens
     incurred in the ordinary course of business; and (C) defects and
     irregularities in title and encumbrances which are not substantial in
     character or amount and do not materially impair the use of the
     property or asset in question (collectively, "Permitted Liens"); or
     (ix) any increase in or establishment of any bonus, insurance,
     severance, deferred compensation, pension, retirement, profit sharing,
     stock option (including, without limitation, the granting of stock
     options, stock appreciation rights, performance awards or restricted
     stock awards), stock purchase or other employee benefit plan or any
     other increase in the compensation payable or to become payable to any
     officers or key employees of Noble or any of the Noble Subsidiaries.
 
          (g) Litigation. Except as disclosed in the Noble Commission Filings or
     as set forth in Section 2.1(g) of the Noble Disclosure Letter, there are no
     claims, actions, suits, investigations, inquiries or proceedings pending
     or, to the knowledge of Noble, overtly threatened against or affecting
     Noble or any of the Noble Subsidiaries or any of their respective
     properties at law or in equity, or any of their respective employee benefit
     plans or fiduciaries of such plans, or before or by any federal, state,
     municipal or other governmental agency or authority, or before any
     arbitration board or panel, wherever located, that individually or in the
     aggregate if adversely determined would have a material adverse effect on
     the financial condition, results of operations or business of Noble and the
     Noble Subsidiaries, taken as a whole, or that involve the risk of criminal
     liability.
 
          (h) Employee Benefit Plans.
 
             (i) Section 2.1(h) of the Noble Disclosure Letter provides a
        description of each of the following which is sponsored, maintained or
        contributed to by Noble, a Noble Subsidiary or any corporation, trade,
        business or entity under common control with Noble or a Noble Subsidiary
        within the meaning of Section 414(b), (c), (m) or (o) of the Code or
        Section 4001 of ERISA (a "Noble ERISA Affiliate") for the benefit of its
        employees, or has been so sponsored, maintained or contributed to within
        six years prior to the Closing Date:
 
                (A) each "employee benefit plan," as such term is defined in
           Section 3(3) of the Employee Retirement Income Security Act of 1974,
           as amended ("ERISA"), ("Plan"); and
 
                (B) each personnel policy, stock option plan, collective
           bargaining agreement, bonus plan or arrangement, incentive award plan
           or arrangement, vacation policy, severance pay plan, policy or
           agreement, deferred compensation agreement or arrangement, executive
           compensation or supplemental income arrangement, consulting
           agreement, employment agreement and each other employee benefit plan,
           agreement, arrangement, program, practice or understanding that is
           not described in Section 2.1(h)(i)(A) ("Benefit Program or
           Agreement").
 
        True and complete copies of each of the Plans, Benefit Programs or
        Agreements, related trusts, if applicable, and all amendments thereto,
        have been furnished to Chiles.
 
             (ii) Except as otherwise set forth in Section 2.1(h) of the Noble
        Disclosure Letter,
 
                (A) None of Noble, any Noble Subsidiary or any Noble ERISA
           Affiliate contributes to or has an obligation to contribute to, or
           has at any time contributed to or had an obligation to contribute to,
           a plan subject to Title IV of ERISA, including, without limitation, a
           multiemployer plan within the meaning of Section 3(37) of ERISA;
 
                (B) Each Plan and each Benefit Program or Agreement has been
           administered, maintained and operated in all material respects in
           accordance with the terms thereof and in
 
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<PAGE>   98
 
           compliance with its governing documents and applicable law
           (including, where applicable, ERISA and the Code);
 
                (C) There is no matter pending with respect to any of the Plans
           before any governmental agency, and there are no actions, suits or
           claims pending (other than routine claims for benefits) or threatened
           against, or with respect to, any of the Plans or Benefit Programs or
           Agreements or their assets;
 
                (D) No act, omission or transaction has occurred which would
           result in imposition on Noble, any Noble Subsidiary or any Noble
           ERISA Affiliate of breach of fiduciary duty liability damages under
           Section 409 of ERISA, a civil penalty assessed pursuant to
           Subsections (c), (i) or (l) of Section 502 of ERISA or a tax imposed
           pursuant to Chapter 43 of Subtitle D of the Code; and
 
                (E) The execution and delivery of this Agreement and the
           consummation of the transactions contemplated hereby will not require
           Noble, any Noble Subsidiary or any Noble ERISA Affiliate to make a
           larger contribution to, or pay greater benefits under, any Plan or
           Benefit Program or Agreement than it otherwise would or create or
           give rise to any additional vested rights or service credits under
           any Plan or Benefit Program or Agreement.
 
             (iii) Termination of employment of any employee of Noble, any Noble
        Subsidiary or any Noble ERISA Affiliate immediately after consummation
        of the transactions contemplated by this Agreement would not result in
        payments under the Plans, Benefit Programs or Agreements which, in the
        aggregate, would result in imposition of the sanctions imposed under
        Sections 280G and 4999 of the Code.
 
             (iv) Each Plan which is an "employee welfare benefit plan," as such
        term is defined in Section 3(1) of ERISA, may be unilaterally amended or
        terminated in its entirety without liability except as to benefits
        accrued thereunder prior to such amendment or termination.
 
             (v) Except as set forth in Section 2.1(h) of the Noble Disclosure
        Letter, none of the employees of Noble, any of the Noble Subsidiaries or
        any Noble ERISA Affiliate are subject to union or collective bargaining
        agreements.
 
          (i) Taxes. Except as set forth in Section 2.1(i) of the Noble
     Disclosure Letter, all returns and reports, including, without limitation,
     information and withholding returns and reports ("Tax Returns"), of or
     relating to any foreign, federal, state or local tax, assessment or other
     governmental charge ("Taxes" or a "Tax") that are required to be filed on
     or before the Closing Date by or with respect to Noble or any of the Noble
     Subsidiaries, or any other corporation that is or was a member of an
     affiliated group (within the meaning of Section 1504(a) of the Code) of
     corporations of which Noble was a member for any period ending on or prior
     to the Closing Date, have been or will be duly and timely filed, and all
     Taxes, including interest and penalties, due and payable pursuant to such
     Tax Returns have been paid or, except as set forth in Section 2.1(i) of the
     Noble Disclosure Letter, adequately provided for in reserves established by
     Noble, except where the failure to file, pay or provide for would not have
     a material adverse effect on the financial condition, results of operations
     or business of Noble and the Noble Subsidiaries, taken as a whole. Except
     as set forth in Section 2.1(i) of the Noble Disclosure Letter, all U.S.
     Federal income Tax Returns of or with respect to Noble and the Noble
     Subsidiaries have been audited by the applicable governmental authority, or
     the applicable statute of limitations has expired, for all periods up to
     and including the taxable year ended December 31, 1989. Except as set forth
     in Section 2.1(i) of the Noble Disclosure Letter, there is no material
     claim against Noble or any of the Noble Subsidiaries with respect to any
     Taxes, and no material assessment, deficiency or adjustment has been
     asserted or proposed with respect to any Tax Return of or with respect to
     Noble or any of the Noble Subsidiaries that has not been adequately
     provided for in reserves established by Noble. The total amounts set up as
     liabilities for current and deferred Taxes in the consolidated financial
     statements included in the Noble Commission Filings have been prepared in
     accordance with generally accepted
 
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<PAGE>   99
 
     accounting principles and, except as set forth in Section 2.1(i) of the
     Noble Disclosure Letter, are sufficient to cover the payment of all
     material Taxes, including any penalties or interest thereon and whether or
     not assessed or disputed, that are, or are hereafter found to be, or to
     have been, due with respect to the operations of Noble and the Noble
     Subsidiaries through the periods covered thereby. Noble and each of the
     Noble Subsidiaries have (and as of the Closing Date will have) made all
     deposits (including estimated tax payments for taxable years for which the
     consolidated federal income tax return is not yet due) required with
     respect to Taxes. Except as set forth in Section 2.1(i) of the Noble
     Disclosure Letter, no waiver or extension of any statute of limitations as
     to any federal, local or foreign Tax matter has been given by or requested
     from Noble or any of the Noble Subsidiaries. Except for statutory liens for
     current Taxes not yet due, no liens for Taxes exist upon the assets of
     either Noble or the Noble Subsidiaries. Except as set forth in Section
     2.1(i) of the Noble Disclosure Letter, neither Noble nor any of the Noble
     Subsidiaries has filed consolidated income Tax Returns with any
     corporation, other than consolidated federal and state income Tax Returns
     by Noble, for any taxable period which is not now closed by the applicable
     statute of limitations. Except as set forth in Section 2.1(i) of the Noble
     Disclosure Letter, neither Noble nor any of the Noble Subsidiaries has any
     deferred intercompany gain as defined in Treasury Regulation Section
     1.1502-13.
 
          Noble has no present plan or intention after the Merger to (i)
     liquidate the Surviving Corporation, (ii) merge the Surviving Corporation
     with or into another corporation, (iii) sell or otherwise dispose of the
     stock of the Surviving Corporation, (iv) cause or permit the Surviving
     Corporation to sell or otherwise dispose of any of the assets of Chiles or
     the assets of Sub vested in the Surviving Corporation except for
     dispositions made in the ordinary course of business or transfers of assets
     to a corporation controlled by the Surviving Corporation within the meaning
     of Section 368(a)(2)(C) of the Code, (v) reacquire any of the stock issued
     to the Chiles stockholders pursuant to the Merger, or (vi) cause or permit
     the Surviving Corporation to discontinue the historic business of Chiles.
 
          (j) Environmental Matters. Except for matters disclosed in Section
     2.1(j) of the Noble Disclosure Letter and except for matters that in the
     aggregate would not have a material adverse effect on the financial
     condition, results of operations or business of Noble and the Noble
     Subsidiaries, taken as a whole, (i) the properties, operations and
     activities of Noble and the Noble Subsidiaries comply with all applicable
     Environmental Laws (as defined below); (ii) Noble and the Noble
     Subsidiaries and the properties and operations of Noble and the Noble
     Subsidiaries are not subject to any existing, pending or, to the knowledge
     of Noble, threatened action, suit, investigation, inquiry or proceeding by
     or before any governmental authority under any Environmental Law; (iii) all
     notices, permits, licenses, or similar authorizations, if any, required to
     be obtained or filed by Noble or the Noble Subsidiaries under any
     Environmental Law in connection with any aspect of the business of Noble or
     the Noble Subsidiaries, including without limitation those relating to the
     treatment, storage, disposal or release of a hazardous substance or solid
     waste, have been duly obtained or filed and will remain valid and in effect
     after the Merger, and Noble and the Noble Subsidiaries are in compliance
     with the terms and conditions of all such notices, permits, licenses and
     similar authorizations; (iv) Noble and the Noble Subsidiaries have
     satisfied and are currently in compliance with all financial responsibility
     requirements applicable to their operations and imposed by the U.S. Coast
     Guard and Minerals Management Service pursuant to OPA (as hereinafter
     defined) or by any other governmental authority under any other
     Environmental Law, and Noble and the Noble Subsidiaries have not received
     any notice of noncompliance with any such financial responsibility
     requirements; (v) to Noble's knowledge, there are no physical or
     environmental conditions existing on any property of Noble and the Noble
     Subsidiaries or resulting from Noble's and the Noble Subsidiaries'
     operations or activities, past or present, at any location, that would give
     rise to any on-site or off-site remedial obligations under any
     Environmental Laws; (vi) to Noble's knowledge, since the effective date of
     the relevant requirements of applicable Environmental Laws, all hazardous
     substances or solid wastes generated by Noble and the Noble Subsidiaries or
     used in connection with their properties or operations have been
     transported only by carriers authorized under Environmental Laws to
     transport such substances and wastes, and disposed of only at treatment,
     storage, and disposal facilities authorized under environmental laws to
     treat, store or dispose of such substances and wastes, and, to the
     knowledge of Noble, such carriers and facilities have been and are
     operating in compliance with such authorizations
 
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<PAGE>   100
 
     and are not the subject of any existing, pending, or overtly threatened
     action, investigation, or inquiry by any governmental authority in
     connection with any Environmental Laws; (vii) there has been no exposure of
     any person or property to hazardous substances, solid waste, or any
     pollutant or contaminant, nor has there been any release of hazardous
     substances, solid waste, or any pollutant or contaminant into the
     environment by Noble or the Noble Subsidiaries or in connection with their
     properties or operations that could reasonably be expected to give rise to
     any claim for damages or compensation; and (viii) Noble and the Noble
     Subsidiaries shall make available to Chiles all internal and external
     environmental audits and studies and all correspondence on substantial
     environmental matters in the possession of Noble and the Noble Subsidiaries
     relating to any of the current or former properties or operations of Noble
     and the Noble Subsidiaries; provided that neither Noble nor any of the
     Noble Subsidiaries shall be required to make available any such audits,
     studies or correspondence that may be subject to the attorney-client
     privilege or similar privilege.
 
          For purposes of this Agreement, the term "Environmental Laws" shall
     mean any and all laws, statutes, ordinances, rules, regulations, orders or
     determinations of any Governmental Authority pertaining to health or the
     environment currently in effect in any and all jurisdictions in which the
     party in question and its subsidiaries own property or conduct business,
     including without limitation, the Clean Air Act, as amended, the
     Comprehensive Environmental, Response, Compensation, and Liability Act of
     1980 ("CERCLA"), as amended, the Federal Water Pollution Control Act, as
     amended, the Occupational Safety and Health Act of 1970, as amended, the
     Resource Conservation and Recovery Act of 1976 ("RCRA"), as amended, the
     Safe Drinking Water Act, as amended, the Toxic Substances Control Act, as
     amended, the Hazardous & Solid Waste Amendments Act of 1984, as amended,
     the Superfund Amendments and Reauthorization Act of 1986, as amended, the
     Hazardous Materials Transportation Act, as amended, the Oil Pollution Act
     of 1990 ("OPA"), any state laws pertaining to the handling of oil and gas
     exploration and production wastes or the use, maintenance, and closure of
     pits and impoundments, and all other environmental conservation or
     protection laws. For purposes of this Agreement, the terms "hazardous
     substance" and "release" have the meanings specified in CERCLA, and the
     terms "solid waste" and "disposal" have the meanings specified in RCRA;
     provided, however, that to the extent the laws of the state in which the
     property is located establish a meaning for "hazardous substance,"
     "release," "solid waste" or "disposal" that is broader than that specified
     in either CERCLA or RCRA, such broader meaning shall apply. For purposes of
     this Agreement, the term "Governmental Authority" includes the United
     States, the state, county, city, and political subdivisions in which the
     party in question owns property or conducts business, and any agency,
     department, commission, board, bureau or instrumentality of any of them
     that exercises jurisdiction over the party in question.
 
          (k) Severance Payments. Except as set forth in Section 2.1(k) of the
     Noble Disclosure Letter, none of Noble or the Noble Subsidiaries will owe a
     severance payment or similar obligation to any of their respective
     employees, officers or directors as a result of the Merger or the
     transactions contemplated by this Agreement, nor will any of such persons
     be entitled to an increase in severance payments or other benefits as a
     result of the Merger or the transactions contemplated by this Agreement in
     the event of the subsequent termination of their employment.
 
          (l) Voting Requirements. The affirmative vote of the holders of a
     majority of the outstanding shares of Noble Common Stock is the only vote
     of the holders of any class or series of the capital stock of Noble
     necessary to approve the Noble Charter Amendment; and the affirmative vote
     of the holders of a majority of the shares of Noble Common Stock present at
     the Noble special stockholders' meeting convened in accordance with Section
     4.3 and entitled to vote thereon is the only vote of the holders of any
     class or series of the capital stock of Noble necessary to approve this
     Agreement.
 
          (m) Interim Operations of Sub. Sub was formed solely for the purpose
     of engaging in the transactions contemplated hereby, has engaged in no
     other business activities and has conducted its operations only as
     contemplated hereby.
 
                                       10
<PAGE>   101
 
     2.2 Representations and Warranties of Chiles. Chiles hereby represents and
         warrants to Noble that:
 
          (a) Organization and Compliance with Law. Each of Chiles and its
     consolidated subsidiaries (the "Chiles Subsidiaries") is a corporation duly
     organized, validly existing and in good standing under the laws of the
     jurisdiction in which it is chartered or organized and has all requisite
     corporate power and corporate authority and all necessary governmental
     authorizations to own, lease and operate all of its properties and assets
     and to carry on its business as now being conducted, except where the
     failure to be so organized, existing or in good standing or to have such
     governmental authority would not have a material adverse effect on the
     financial condition, results of operations or business of Chiles and the
     Chiles Subsidiaries, taken as a whole. Except as set forth in Section
     2.2(a) of the disclosure letter delivered by Chiles to Noble on the date
     hereof (the "Chiles Disclosure Letter"), each of Chiles and the Chiles
     Subsidiaries is duly qualified as a foreign corporation to do business, and
     is in good standing, in each jurisdiction in which the property owned,
     leased or operated by it or the nature of the business conducted by it
     makes such qualification necessary, except in such jurisdictions where the
     failure to be duly qualified does not and would not, either individually or
     in the aggregate, have a material adverse effect on the financial
     condition, results of operations or business of Chiles and the Chiles
     Subsidiaries, taken as a whole. Each of Chiles and the Chiles Subsidiaries
     is in compliance with all applicable laws, judgments, orders, rules and
     regulations, domestic and foreign, except where failure to be in such
     compliance would not have a material adverse effect on the financial
     condition, results of operations or business of Chiles and the Chiles
     Subsidiaries, taken as a whole. Chiles has heretofore delivered to Noble
     true and complete copies of Chiles's Certificate of Incorporation (the
     "Chiles Certificate") and bylaws as in existence on the date hereof.
 
        (b) Capitalization.
 
             (i) The authorized capital stock of Chiles consists of 60,000,000
        shares of Chiles Common Stock, par value $.01 per share, and 10,000,000
        shares of Chiles Preferred Stock, par value $1.00 per share. As of May
        31, 1994, there were issued and outstanding 38,131,780 shares of Chiles
        Common Stock, and 4,025,000 shares of Chiles Preferred Stock and no
        shares of Chiles Common Stock or Chiles Preferred Stock were held as
        treasury shares. A total of 3,400,000 shares of Chiles Common Stock have
        been reserved for issuance pursuant to the stock option plans described
        in Section 2.2(b)(ii). All issued shares of Chiles Common Stock are
        validly issued, fully paid and nonassessable and no holder thereof is
        entitled to preemptive rights. Except as set forth in Section 2.2(b) of
        the Chiles Disclosure Letter, Chiles is not a party to, and is not aware
        of, any voting agreement, voting trust or similar agreement or
        arrangement relating to any class or series of its capital stock, or any
        agreement or arrangement providing for registration rights with respect
        to any capital stock or other securities of Chiles.
 
             (ii) As of the date hereof, there are outstanding options (the
        "Chiles Options") to purchase an aggregate of 1,073,800 shares of Chiles
        Common Stock under the Amended and Restated 1990 Stock Option Plan (the
        "Chiles 1990 Plan"). There are no options outstanding under Chiles's
        1994 Stock Option Plan. Other than as set forth in this Section 2.2(b),
        there are not now, and at the Effective Time there will not be, any (A)
        shares of capital stock or other equity securities of Chiles outstanding
        other than Chiles Common Stock issued pursuant to the exercise of Chiles
        Options or upon the conversion of any convertible securities of Chiles
        outstanding on the date hereof as described herein or (B) outstanding
        options, warrants, scrip, rights to subscribe for, calls or commitments
        of any character whatsoever relating to, or securities or rights
        convertible into or exchangeable for, shares of any class of capital
        stock of Chiles, or contracts, understandings or arrangements to which
        Chiles is a party, or by which it is or may be bound, to issue
        additional shares of its capital stock or options, warrants, scrip or
        rights to subscribe for, or securities or rights convertible into or
        exchangeable for, any additional shares of its capital stock.
 
             (iii) Except as set forth in Section 2.2(b) of the Chiles
        Disclosure Letter, all outstanding shares of capital stock of the Chiles
        Subsidiaries are owned by Chiles or a wholly-owned subsidiary of Chiles,
        free and clear of all liens, charges, encumbrances, adverse claims and
        options of any nature which are material to Chiles and the Chiles
        Subsidiaries, taken as a whole.
 
                                       11
<PAGE>   102
 
          (c) Authorization and Validity of Agreement. Chiles has all requisite
     corporate power and authority to enter into this Agreement and to perform
     its obligations hereunder. The execution and delivery by Chiles of this
     Agreement and the consummation by it of the transactions contemplated
     hereby have been duly authorized by all necessary corporate action (subject
     only, with respect to the Merger, to approval of this Agreement by its
     stockholders as provided for in Section 3.3). On or prior to the date
     hereof the Board of Directors of Chiles has determined to recommend
     approval of the Merger to the stockholders of Chiles, and such
     determination is in effect as of the date hereof. This Agreement has been
     duly executed and delivered by Chiles and is the valid and binding
     obligation of Chiles, enforceable against Chiles in accordance with its
     terms.
 
          (d) No Approvals or Notices Required; No Conflict with Instruments to
     which Chiles or any of the Chiles Subsidiaries is a Party. Except as set
     forth in Section 2.2(d) of the Chiles Disclosure Letter, neither the
     execution and delivery of this Agreement nor the performance by Chiles of
     its obligations hereunder, nor the consummation of the transactions
     contemplated hereby by Chiles, will (i) conflict with the Chiles
     Certificate or the bylaws of Chiles or the charter or bylaws of any of the
     Chiles Subsidiaries; (ii) assuming satisfaction of the requirements set
     forth in clause (iii) below, violate any provision of law applicable to
     Chiles or any of the Chiles Subsidiaries; (iii) except for (A) requirements
     of Federal or state securities laws, (B) requirements arising out of the
     HSR Act, (C) requirements of notice filings in such foreign jurisdictions
     as may be applicable, and (D) the filing of articles of merger in
     accordance with the DGCL, require any consent or approval of, or filing
     with or notice to, any public body or authority, domestic or foreign, under
     any provision of law applicable to Chiles or any of the Chiles
     Subsidiaries; or (iv) require any consent, approval or notice under, or
     violate, breach, be in conflict with or constitute a default (or an event
     that, with notice or lapse of time or both, would constitute a default)
     under, or permit the termination of any provision of, or result in the
     creation or imposition of any lien upon any properties, assets or business
     of Chiles or any of the Chiles Subsidiaries under, any note, bond,
     indenture, mortgage, deed of trust, lease, franchise, permit,
     authorization, license, contract, instrument or other agreement or
     commitment or any order, judgment or decree to which Chiles or any of the
     Chiles Subsidiaries is a party or by which Chiles or any of the Chiles
     Subsidiaries or any of its or their assets or properties is bound or
     encumbered, except (A) those that have already been given, obtained or
     filed, (B) those that are required pursuant to bank loan agreements or
     leasing arrangements, as set forth in Section 2.2(d) of the Chiles
     Disclosure Letter, which will be obtained prior to the Effective Time, and
     (C) those that, in the aggregate, would not have a material adverse effect
     on the financial condition, results of operations or business of Chiles and
     the Chiles Subsidiaries, taken as a whole.
 
          (e) Commission Filings; Financial Statements. Chiles and each of the
     Chiles Subsidiaries have filed all reports, registration statements and
     other filings, together with any amendments required to be made with
     respect thereto, that they have been required to file with the Commission
     under the Securities Act and the Exchange Act. All reports, registration
     statements and other filings (including all notes, exhibits and schedules
     thereto and documents incorporated by reference therein) filed by Chiles
     with the Commission since January 1, 1992 through the date of this
     Agreement, together with any amendments thereto, are sometimes collectively
     referred to as the "Chiles Commission Filings." Chiles has heretofore
     delivered to Noble copies of the Chiles Commission Filings. As of the
     respective dates of their filing with the Commission, the Chiles Commission
     Filings complied in all material respects with the Securities Act, the
     Exchange Act and the rules and regulations of the Commission thereunder,
     and did not contain any untrue statement of a material fact or omit to
     state a material fact required to be stated therein or necessary to make
     the statements made therein, in light of the circumstances under which they
     were made, not misleading.
 
          All material contracts of Chiles and the Chiles Subsidiaries have been
     included in the Chiles Commission Filings, except for those contracts not
     required to be filed pursuant to the rules and regulations of the
     Commission.
 
          Each of the consolidated financial statements (including any related
     notes or schedules) included in the Chiles Commission Filings was prepared
     in accordance with generally accepted accounting principles applied on a
     consistent basis (except as may be noted therein or in the notes or
     schedules thereto) and
 
                                       12
<PAGE>   103
 
     complied with the rules and regulations of the Commission. Such
     consolidated financial statements fairly present the consolidated
     financial position of Chiles and the Chiles Subsidiaries as of the
     dates thereof and the results of operations, cash flows and changes in
     shareholders' equity for the periods then ended (subject, in the case
     of the unaudited interim financial statements, to normal year-end audit
     adjustments on a basis comparable with past periods). As of the date
     hereof, Chiles has no liabilities, absolute or contingent, that may
     reasonably be expected to have a material adverse effect on the
     financial condition, results of operations or business of Chiles and
     the Chiles Subsidiaries, taken as a whole, that are not reflected in
     the Chiles Commission Filings, except (i) those incurred in the
     ordinary course of business consistent with past operations and not
     relating to the borrowing of money, and (ii) those set forth in Section
     2.2(e) of the Chiles Disclosure Letter.
 
          (f) Conduct of Business in the Ordinary Course; Absence of Certain
     Changes and Events. Since January 1, 1994, except as contemplated by this
     Agreement or as disclosed in the Chiles Commission Filings filed with the
     Commission prior to the date hereof or as set forth in Section 2.2(f) of
     the Chiles Disclosure Letter, Chiles and the Chiles Subsidiaries have
     conducted their business only in the ordinary and usual course, and there
     has not been (i) any material adverse change in the financial condition,
     results of operations, or business of Chiles and the Chiles Subsidiaries,
     taken as a whole, or any condition, event or development that reasonably
     may be expected to result in any such material adverse change; (ii) any
     material change by Chiles in its accounting methods, principles or
     practices; (iii) any revaluation by Chiles or any of the Chiles
     Subsidiaries of any of its or their assets, including, without limitation,
     writing down the value of inventory or writing off notes or accounts
     receivable other than in the ordinary course of business; (iv) any entry by
     Chiles or any of the Chiles Subsidiaries into any commitment or transaction
     material to Chiles and the Chiles Subsidiaries, as a whole; (v) any
     declaration, setting aside or payment of any dividends or distributions in
     respect of the Chiles Common Stock or any redemption, purchase or other
     acquisition of any of its securities or any securities of any of the Chiles
     Subsidiaries; (vi) any damage, destruction or loss (whether or not covered
     by insurance) materially adversely affecting the properties or business of
     Chiles and the Chiles Subsidiaries, taken as a whole; (vii) any increase in
     indebtedness for borrowed money; (viii) any granting of a security interest
     or lien on any material property or assets of Chiles and the Chiles
     Subsidiaries, taken as a whole, other than Permitted Liens; or (ix) any
     increase in or establishment of any bonus, insurance, severance, deferred
     compensation, pension, retirement, profit sharing, stock option (including,
     without limitation, the granting of stock options, stock appreciation
     rights, performance awards or restricted stock awards), stock purchase or
     other employee benefit plan or any other increase in the compensation
     payable or to become payable to any officers or key employees of Chiles or
     any of the Chiles Subsidiaries.
 
          (g) Litigation. Except as disclosed in the Chiles Commission Filings
     or as set forth in Section 2.2(g) of the Chiles Disclosure Letter, there
     are no claims, actions, suits, investigations, inquiries or proceedings
     pending or, to the knowledge of Chiles, overtly threatened against or
     affecting Chiles or any of the Chiles Subsidiaries or any of their
     respective properties at law or in equity, or any of their respective
     employee benefit plans or fiduciaries of such plans, or before or by any
     federal, state, municipal or other governmental agency or authority, or
     before any arbitration board or panel, wherever located, that individually
     or in the aggregate if adversely determined would have a material adverse
     effect on the financial condition, results of operations or business of
     Chiles and the Chiles Subsidiaries, taken as a whole, or that involve the
     risk of criminal liability.
 
          (h) Employee Benefit Plans.
 
             (i) Section 2.2(h) of the Chiles Disclosure Letter provides a
        description of each Plan or Benefit Program or Agreement which is
        sponsored, maintained or contributed to by Chiles, a Chiles Subsidiary
        or any corporation, trade, business or entity under common control with
        Chiles or a Chiles Subsidiary within the meaning of Section 414(b), (c),
        (m) or (o) of the Code or Section 4001 of ERISA (an "Chiles ERISA
        Affiliate") for the benefit of its employees, or has been so sponsored,
        maintained or contributed to within six years prior to the Closing Date.
        True and
 
                                       13
<PAGE>   104
 
           complete copies of each of the Plans, Benefit Programs or Agreements,
           related trusts, if applicable, and all amendments thereto, have been
           furnished to Noble.
 
          (ii) Except as otherwise set forth in Section 2.2(h) of the Chiles
     Disclosure Letter,
 
                (A) None of Chiles, any Chiles Subsidiary or any Chiles ERISA
           Affiliate contributes to or has an obligation to contribute to, or
           has at any time contributed to or had an obligation to contribute to,
           a plan subject to Title IV of ERISA, including, without limitation, a
           multiemployer plan within the meaning of Section 3(37) of ERISA;
 
                (B) Each Plan and each Benefit Program or Agreement has been
           administered, maintained and operated in all material respects in
           accordance with the terms thereof and in compliance with its
           governing documents and applicable law (including, where applicable,
           ERISA and the Code);
 
                (C) There is no matter pending with respect to any of the Plans
           before any governmental agency, and there are no actions, suits or
           claims pending (other than routine claims for benefits) or threatened
           against, or with respect to, any of the Plans or Benefit Programs or
           Agreements or their assets;
 
                (D) No act, omission or transaction has occurred which would
           result in imposition on Chiles, any Chiles Subsidiary or any Chiles
           ERISA Affiliate of breach of fiduciary duty liability damages under
           Section 409 of ERISA, a civil penalty assessed pursuant to
           subSections (c), (i) or (l) of Section 502 of ERISA or a tax imposed
           pursuant to Chapter 43 of Subtitle D of the Code; and
 
                (E) Except as provided in Section 5.11, the execution and
           delivery of this Agreement and the consummation of the transactions
           contemplated hereby will not require Chiles, any Chiles Subsidiary or
           any Chiles ERISA Affiliate to make a larger contribution to, or pay
           greater benefits under, any Plan, Benefit Program or Agreement than
           it otherwise would or create or give rise to any additional vested
           rights or service credits under any Plan or Benefit Program or
           Agreement.
 
             (iii) Termination of employment of any employee of Chiles, any
        Chiles Subsidiary or any Chiles ERISA Affiliate immediately after
        consummation of the transactions contemplated by this Agreement would
        not result in payments under the Plans, Benefit Programs or Agreements
        which, in the aggregate, would result in imposition of the sanctions
        imposed under Sections 280G and 4999 of the Code.
 
             (iv) Each Plan which is an "employee welfare benefit plan," as such
        term is defined in Section 3(1) of ERISA, may be unilaterally amended or
        terminated in its entirety without liability except as to benefits
        accrued thereunder prior to such amendment or termination.
 
             (v) None of the employees of Chiles, any of the Chiles Subsidiaries
        or any Chiles ERISA Affiliate are subject to union or collective
        bargaining agreements.
 
          (i) Taxes. Except as set forth in Section 2.2(i) of the Chiles
     Disclosure Letter, all Tax Returns of or relating to any Tax that are
     required to be filed on or before the Closing Date by or with respect to
     Chiles or any of the Chiles Subsidiaries, or any other corporation that is
     or was a member of an affiliated group (within the meaning of Section 1504
     (a) of the Code) of corporations of which Chiles was a member for any
     period ending on or prior to the Closing Date, have been or will be duly
     and timely filed, and all Taxes, including interest and penalties, due and
     payable pursuant to such Tax Returns have been paid or adequately provided
     for in reserves established by Chiles, except where the failure to file,
     pay or provide for would not have a material adverse effect on the
     financial condition, results of operations or business of Chiles and the
     Chiles Subsidiaries, taken as a whole. Except as set forth in Section
     2.2(i) of the Chiles Disclosure Letter, all U.S. Federal income Tax Returns
     of or with respect to Chiles or any of the Chiles Subsidiaries have been
     audited by the applicable governmental authority, or the applicable
 
                                       14
<PAGE>   105
 
     statute of limitations has expired, for all periods up to and including the
     tax year ended December 31, 1989. There is no material claim against Chiles
     or any of the Chiles Subsidiaries with respect to any Taxes, and no
     material assessment, deficiency or adjustment has been asserted or proposed
     with respect to any Tax Return of or with respect to Chiles or any of the
     Chiles Subsidiaries that has not been adequately provided for in reserves
     established by Chiles. The total amounts set up as liabilities for current
     and deferred Taxes in the consolidated financial statements included in the
     Chiles Commission Filings have been prepared in accordance with generally
     accepted accounting principles and are sufficient to cover the payment of
     all material Taxes, including any penalties or interest thereon and whether
     or not assessed or disputed, that are, or are hereafter found to be, or to
     have been, due with respect to the operations of Chiles and the Chiles
     Subsidiaries through the periods covered thereby. Chiles and each of the
     Chiles Subsidiaries have (and as of the Closing Date will have) made all
     deposits (including estimated tax payments for taxable years for which the
     consolidated federal income tax return is not yet due) required with
     respect to Taxes. Except as set forth in Section 2.2(i) of the Chiles
     Disclosure Letter, no waiver or extension of any statute of limitations as
     to any federal, local or foreign Tax matter has been given by or requested
     from Chiles or any of the Chiles Subsidiaries. Except for statutory liens
     for current Taxes not yet due, no liens for Taxes exist upon the assets of
     either Chiles or the Chiles Subsidiaries. Except as set forth in Section
     2.2(i) of the Chiles Disclosure Letter, neither Chiles nor any of the
     Chiles Subsidiaries has filed consolidated income Tax Returns with any
     corporation, other than consolidated federal and state income Tax Returns
     by Chiles, for any taxable period which is not now closed by the applicable
     statute of limitations. Neither Chiles nor the Chiles Subsidiaries has any
     deferred intercompany gain as defined in Treasury Regulation Section
     1.1502-13.
 
          In the Merger, at least 90% of the fair market value of Chiles's net
     assets and at least 70% of the fair market value of Chiles's gross assets
     held immediately prior to the Merger will be vested in Sub. For purposes of
     this representation, amounts paid by Chiles to stockholders who receive
     cash or other property, amounts used by Chiles to pay reorganization
     expenses, and all redemptions and distributions (except for regular, normal
     dividends) made by Chiles will be included as assets of Chiles immediately
     prior to the Merger. As of the Closing Date, there is no plan or intention
     by the stockholders of Chiles to sell, exchange or otherwise dispose of a
     number of shares of Noble received in the Merger that would reduce the
     Chiles stockholders' ownership of Noble shares to a number of shares having
     a value, as of the date of the Merger, of less than 50% of the value of all
     of the formerly outstanding Shares as of the same date. For purposes of
     this representation, Shares exchanged for cash or other property or
     exchanged in lieu of fractional shares of Noble will be treated as
     outstanding Shares on the date of the Merger. Moreover, the shares of Noble
     held by the Chiles stockholders and otherwise sold, redeemed or disposed of
     prior or subsequent to the Merger will be considered in making this
     representation.
 
          (j) Environmental Matters. Except for matters disclosed in Section
     2.2(j) of the Chiles Disclosure Letter and except for matters that in the
     aggregate would not have a material adverse effect on the financial
     condition, results of operations or business of Chiles and the Chiles
     Subsidiaries, taken as a whole, (i) the properties, operations and
     activities of Chiles and the Chiles Subsidiaries comply with all applicable
     Environmental Laws; (ii) Chiles and the Chiles Subsidiaries and the
     properties and operations of Chiles and the Chiles Subsidiaries are not
     subject to any existing, pending or, to the knowledge of Chiles, threatened
     action, suit, investigation, inquiry or proceeding by or before any
     governmental authority under any Environmental Law; (iii) all notices,
     permits, licenses, or similar authorizations, if any, required to be
     obtained or filed by Chiles or the Chiles Subsidiaries under any
     Environmental Law in connection with any aspect of the business of Chiles
     or the Chiles Subsidiaries, including without limitation those relating to
     the treatment, storage, disposal or release of a hazardous substance or
     solid waste, have been duly obtained or filed and will remain valid and in
     effect after the Merger, and Chiles and the Chiles Subsidiaries are in
     compliance with the terms and conditions of all such notices, permits,
     licenses and similar authorizations; (iv) Chiles and the Chiles
     Subsidiaries have satisfied and are currently in compliance with all
     financial responsibility requirements applicable to their operations and
     imposed by the U.S. Coast Guard and Minerals Management Service pursuant to
     OPA (as hereinafter defined) or by any other governmental authority under
     any other Environmental Law, and Chiles and the Chiles Subsidiaries have
     not received any notice of noncompliance with any such financial
     responsibility
 
                                       15
<PAGE>   106
 
      requirements; (v) to Chiles's knowledge, there are no physical or
      environmental conditions existing on any property of Chiles and the
      Chiles Subsidiaries or resulting from Chiles's and the Chiles
      Subsidiaries' operations or activities, past or present, at any
      location, that would give rise to any on-site or off-site remedial
      obligations under any Environmental Laws; (vi) to Chiles's knowledge,
      since the effective date of the relevant requirements of applicable
      Environmental Laws, all hazardous substances or solid wastes generated
      by Chiles and the Chiles Subsidiaries or used in connection with their
      properties or operations have been transported only by carriers
      authorized under Environmental Laws to transport such substances and
      wastes, and disposed of only at treatment, storage, and disposal
      facilities authorized under environmental laws to treat, store or
      dispose of such substances and wastes, and, to the knowledge of Chiles,
      such carriers and facilities have been and are operating in compliance
      with such authorizations and are not the subject of any existing,
      pending, or overtly threatened action, investigation, or inquiry by any
      governmental authority in connection with any Environmental Laws; (vii)
      there has been no exposure of any person or property to hazardous
      substances, solid waste, or any pollutant or contaminant, nor has there
      been any release of hazardous substances, solid waste, or any pollutant
      or contaminant into the environment by Chiles or the Chiles
      Subsidiaries or in connection with their properties or operations that
      could reasonably be expected to give rise to any claim for damages or
      compensation; and (viii) Chiles and the Chiles Subsidiaries shall make
      available to Noble all internal and external environmental audits and
      studies and all correspondence on substantial environmental matters in
      the possession of Chiles and the Chiles Subsidiaries relating to any of
      the current or former properties or operations of Chiles and the Chiles
      Subsidiaries; provided that neither Chiles nor any of the Chiles
      Subsidiaries shall be required to make available any such audits,
      studies or correspondence that may be subject to the attorney-client
      privilege or similar privilege.
 
          (k) Severance Payments. Except as set forth in Section 2.2(k) of the
     Chiles Disclosure Letter, none of Chiles or the Chiles Subsidiaries will
     owe a severance payment or similar obligation to any of their respective
     employees, officers or directors as a result of the Merger or the
     transactions contemplated by this Agreement, nor will any of such persons
     be entitled to an increase in severance payments or other benefits as a
     result of the Merger or the transactions contemplated by this Agreement in
     the event of the subsequent termination of their employment.
 
          (l) Voting Requirements. The affirmative vote of the holders of a
     majority of the outstanding shares of Chiles Common Stock is the only vote
     of the holders of any class or series of the capital stock of Chiles
     necessary to approve this Agreement and the Merger.
 
                                  ARTICLE III
 
                COVENANTS OF CHILES PRIOR TO THE EFFECTIVE TIME
 
     3.1 Conduct of Business by Chiles Pending the Merger. Chiles covenants and
agrees that, from the date of this Agreement until the Effective Time, unless
Noble shall otherwise agree in writing or as otherwise expressly contemplated by
this Agreement or set forth in Section 3.1 of the Chiles Disclosure Letter:
 
          (a) the business of Chiles and the Chiles Subsidiaries shall be
     conducted only in, and Chiles and the Chiles Subsidiaries shall not take
     any action except in, the ordinary course of business and consistent with
     past practice; in addition, from and after the date of this Agreement,
     Chiles shall not, and shall not permit any of the Chiles Subsidiaries to,
     (i) enter into any new drilling contracts with respect to any of Chiles'
     drilling rigs unless in the good faith opinion of Chiles such contracts may
     reasonably be expected to have a duration of 90 days or less, or amend in
     any material respect adverse to Chiles or Noble any drilling contract or
     other material contract or agreement, without giving prior written notice
     to Noble, or (ii) mobilize any of Chiles' drilling rigs from the Gulf of
     Mexico or from the West African coast, without giving prior written notice
     to Noble;
 
          (b) Chiles shall not directly or indirectly do any of the following:
     (i) issue, sell, pledge, dispose of or encumber, or permit any Chiles
     Subsidiary to issue, sell, pledge, dispose of or encumber, (A) any capital
     stock of Chiles or any Chiles Subsidiary except upon the exercise of Chiles
     Options or upon conversion of
 
                                       16
<PAGE>   107
 
     any convertible securities of Chiles outstanding as of the date of this
     Agreement or (B) other than in the ordinary course of business and
     consistent with past practice and not relating to the borrowing of
     money, any assets of Chiles or any Chiles Subsidiary; (ii) amend or
     propose to amend the respective charters or bylaws of Chiles or any
     Chiles Subsidiary; (iii) split, combine or reclassify any outstanding
     capital stock, or declare, set aside or pay any dividend payable in
     cash, stock, property or otherwise with respect to its capital stock
     whether now or hereafter outstanding other than its regular quarterly
     cash dividends on the Chiles Preferred Stock; (iv) redeem, purchase or
     acquire or offer to acquire, or permit any of the Chiles Subsidiaries
     to redeem, purchase or acquire or offer to acquire, any of its or their
     capital stock; (v) except in the ordinary course of business and
     consistent with past practice, enter into any contract, agreement,
     commitment or arrangement with respect to any of the matters set forth
     in this Section 3.1(b); (vi) enter into, adopt or (except as may be
     required by law and except for an amendment to the Chiles 1990 Plan (or
     any option agreements existing thereunder) to provide the Board of
     Directors of Chiles with the power to take the actions required
     pursuant to Section 5.11) amend or terminate any bonus, profit sharing,
     compensation, severance, termination, stock option, stock appreciation
     right, restricted stock, performance unit, stock equivalent, stock
     purchase, pension, retirement, deferred compensation, employment,
     severance or other employee benefit agreement, trust, plan, fund or
     other arrangement for the benefit or welfare of any director, officer
     or employee; (vii) except as provided in Section 5.11 and except for
     normal increases in the ordinary course of business consistent with
     past practice that, in the aggregate, do not result in a material
     increase in benefits or compensation expense, increase in any manner
     the compensation or fringe benefits of any director, officer or
     employee; or (viii) except as provided in Section 5.11, pay to any
     director, officer or employee any benefit not required by any employee
     benefit agreement, trust, plan, fund or other arrangement as in effect
     on the date hereof;
 
          (c) Chiles shall use its reasonable efforts (i) to preserve intact the
     business organization of Chiles and each of the Chiles Subsidiaries, (ii)
     to maintain in effect any authorizations or similar rights of Chiles and
     each of the Chiles Subsidiaries, (iii) to keep available the services of
     its and their current officers and key employees, (iv) to preserve the
     goodwill of those having business relationships with it and the Chiles
     Subsidiaries, (v) to maintain and keep its properties and the properties of
     the Chiles Subsidiaries in as good a repair and condition as presently
     exists, except for deterioration due to ordinary wear and tear and damage
     due to casualty; and (vi) to maintain in full force and effect insurance
     comparable in amount and scope of coverage to that currently maintained by
     it and the Chiles Subsidiaries;
 
          (d) Chiles shall not make or agree to make, or permit any of the
     Chiles Subsidiaries to make or agree to make, new capital expenditures that
     in the aggregate exceed $500,000;
 
          (e) neither Chiles nor any of the Chiles Subsidiaries shall take, and
     Chiles will use its reasonable efforts to prevent any affiliate of Chiles
     from taking, any action that, in the judgment of Arthur Andersen & Co.,
     Chiles's independent auditors, would cause the Merger not to be treated as
     a "pooling of interests" for accounting purposes;
 
          (f) Chiles shall, and shall cause the Chiles Subsidiaries to, perform
     their respective obligations under any contracts and agreements to which
     any of them is a party or to which any of their assets is subject, except
     to the extent such failure to perform would not have a material adverse
     effect on Chiles and the Chiles Subsidiaries, taken as a whole, and except
     for such obligations as Chiles or the Chiles Subsidiaries in good faith may
     dispute; and
 
          (g) Chiles shall not, and shall not permit any of the Chiles
     Subsidiaries to, take any action that would, or that reasonably could be
     expected to, result in any of the representations and warranties set forth
     in this Agreement becoming untrue or any of the conditions to the Merger
     set forth in Article VI not being satisfied. Chiles promptly shall advise
     Noble orally and in writing of any change or event having, or which,
     insofar as reasonably can be foreseen, would have, a material adverse
     effect on Chiles and the Chiles Subsidiaries, taken as a whole.
 
     3.2 Joint Proxy Statement. Promptly after the date of this Agreement,
Chiles shall cooperate with Noble in preparing and shall file with the
Commission under the Exchange Act, and shall use its reasonable efforts to
 
                                       17
<PAGE>   108
 
have cleared by the Commission, a joint proxy statement (the "Proxy Statement")
with respect to the meeting of stockholders of Chiles referred to in Section 3.3
and Chiles shall cooperate with Noble in preparing the Registration Statement
(as defined below in Section 4.4). Chiles agrees that the Proxy Statement
(except with respect to information concerning Noble and the Noble Subsidiaries
furnished by or on behalf of Noble specifically for use therein, for which
information Noble shall be responsible) will comply as to form in all material
respects with the requirements of the Exchange Act and the rules and regulations
adopted thereunder, and the Registration Statement (with respect to information
concerning Chiles and the Chiles Subsidiaries provided by Chiles specifically
for use therein) and the Proxy Statement (except with respect to information
concerning Noble and the Noble Subsidiaries furnished by or on behalf of Noble
specifically for use therein, for which information Noble shall be responsible)
will not contain any untrue statement of a material fact or omit to state any
material fact required to be stated therein or necessary to make the statements
therein not misleading. Subject to the terms and conditions of Section 3.4, the
Proxy Statement shall contain the recommendation of the Board of Directors of
Chiles that the stockholders of Chiles vote to approve and adopt this Agreement.
Chiles will advise Noble promptly in writing if prior to the Effective Time it
shall obtain knowledge of any facts that would make it necessary to amend or
supplement the Proxy Statement (or the Registration Statement of which the Proxy
Statement is a part) in order to make the statements therein not misleading or
to comply with applicable law.
 
     3.3 Meeting of Stockholders of Chiles. Subject to the terms and conditions
set forth in Section 3.4, Chiles shall promptly take all action reasonably
necessary in accordance with the DGCL and the Chiles Certificate and bylaws to
convene a meeting of its stockholders to consider and vote upon the adoption and
approval of this Agreement. Subject to the terms and conditions set forth in
Section 3.4, the Board of Directors of Chiles (i) shall recommend at such
meeting that the stockholders of Chiles vote to adopt and approve this
Agreement; (ii) shall use its reasonable efforts to solicit from stockholders of
Chiles proxies in favor of such adoption and approval; and (iii) shall take all
other action reasonably necessary to secure a vote of its stockholders in favor
of the adoption and approval of this Agreement.
 
     3.4 No Shopping. From and after the date of this Agreement, neither Chiles
nor any Chiles Subsidiary shall, directly or indirectly, through any officer,
director, employee, representative or agent of Chiles or any of the Chiles
Subsidiaries, solicit or knowingly encourage, including by way of furnishing
information, the initiation of any inquiries or proposals regarding (i) any
merger, tender offer, sale of shares of capital stock or similar business
combination transactions involving Chiles or the Chiles Subsidiaries that would
have the effect of causing the holders of Chiles Common Stock immediately prior
to the effectiveness of such proposed transaction to own in the aggregate less
than 50% of the shares of the surviving or resulting entity entitled to vote
generally for the election of directors of the surviving or resulting entity, or
(ii) any sale of all or substantially all the assets of Chiles and the Chiles
Subsidiaries, taken as a whole (any of the foregoing transactions being referred
to herein as a "Chiles Acquisition Transaction"); provided, however, that
nothing in this Section 3.4 or elsewhere in this Agreement shall prevent the
members of the Board of Directors of Chiles in the exercise of their fiduciary
duties and after consulting with independent counsel, from considering,
negotiating and approving an unsolicited bona fide proposal that the Board of
Directors of Chiles determines in good faith, after consultation with its
financial advisors, may result in a transaction more favorable to Chiles'
stockholders than the transactions contemplated by this Agreement. If the Board
of Directors of Chiles receives a request for confidential information by a
potential bidder for Chiles and the Board of Directors determines, after
consultation with independent counsel, that the Board of Directors has a
fiduciary obligation to provide such information to a potential bidder, then
Chiles may, subject to a confidentiality agreement substantially similar to that
previously executed by Noble, provide such potential bidder with access to
information regarding Chiles. Chiles shall promptly notify Noble, orally and in
writing, if any such proposal or offer is made and shall, in any such notice,
indicate the identity and terms and conditions of any proposal or offer, or any
such inquiry or contact. Chiles shall keep Noble advised of the progress and
status of any such proposals or offers. The obligation of the Board of Directors
of Chiles to convene a meeting of its stockholders and to recommend the adoption
and approval of this Agreement to the stockholders of Chiles pursuant to Section
3.3 of this Agreement shall be subject to the fiduciary duties of the directors,
as determined by the directors after consultation with their independent
counsel, and nothing contained in this Section 3.4 or elsewhere in this
Agreement shall prevent the Board of Directors of Chiles from approving or
recommending
 
                                       18
<PAGE>   109
 
to the stockholders of Chiles any unsolicited offer or proposal by a third party
if required in the exercise of their fiduciary duties, as determined by the
directors after consultation with independent counsel.
 
     3.5 Affiliates' Agreements. Prior to the Closing Date, Chiles shall deliver
to Noble a letter identifying all persons whom it believes are, at the time this
Agreement is submitted for approval to the stockholders of Chiles, "affiliates"
of Chiles for purposes of Rule 145 under the Securities Act. Chiles shall use
its reasonable efforts to cause each such person to deliver to Noble on or prior
to the Closing Date a written agreement substantially in the form of Exhibit A.
Noble shall not be required to maintain the effectiveness of the Registration
Statement (as defined below) for the purpose of resale by stockholders of Chiles
who may be "affiliates" pursuant to Rule 145 under the Securities Act.
 
                                   ARTICLE IV
 
                 COVENANTS OF NOBLE PRIOR TO THE EFFECTIVE TIME
 
     4.1 Conduct of Business by Noble Pending the Merger. Noble covenants and
agrees that, from the date of this Agreement until the Effective Time, unless
Chiles shall otherwise agree in writing or as otherwise expressly contemplated
by this Agreement:
 
          (a) the business of Noble and the Noble Subsidiaries shall be
     conducted only in, and Noble and the Noble Subsidiaries shall not take any
     action except in, the ordinary course of business and consistent with past
     practice;
 
          (b) except as set forth in Section 4.1(b) of the Noble Disclosure
     Letter, Noble shall not directly or indirectly do any of the following: (i)
     issue, sell, pledge, dispose of or encumber, or permit any Noble Subsidiary
     to issue, sell, pledge, dispose of or encumber, (A) any capital stock of
     Noble or any Noble Subsidiary except upon the exercise of Noble Options or
     upon conversion of any convertible securities of Noble outstanding as of
     the date of this Agreement or pursuant to Noble's Thrift Plan, Noble
     (International) Employees' Retirement Savings Plan or Noble Field Hourly
     Employees' Retirement Plan or (B) other than in the ordinary course of
     business and consistent with past practice and not relating to the
     borrowing of money, any assets of Noble or any Noble Subsidiary; (ii) amend
     or propose to amend the respective charters or bylaws of Noble or any Noble
     Subsidiary, (iii) split, combine or reclassify any outstanding capital
     stock, or declare, set aside or pay any dividend payable in cash, stock,
     property or otherwise with respect to its capital stock whether now or
     hereafter outstanding other than its regular quarterly cash dividends on
     the $2.25 Noble Preferred Stock; (iv) redeem, purchase or acquire or offer
     to acquire, or permit any of the Noble Subsidiaries to redeem, purchase or
     acquire or offer to acquire, any of its or their capital stock; or (v)
     except in the ordinary course of business and consistent with past
     practice, enter into any contract, agreement, commitment or arrangement
     with respect to any of the matters set forth in this Section 4.1 (b);
 
          (c) except as set forth in Section 4.1(c) of the Noble Disclosure
     Letter, Noble shall use its reasonable efforts (i) to preserve intact the
     business organization of Noble and each of the Noble Subsidiaries, (ii) to
     maintain in effect any authorizations, or similar rights of Noble and each
     of the Noble Subsidiaries, (iii) to keep available the services of its and
     their current officers and key employees, (iv) to preserve the goodwill of
     those having business relationships with it and the Noble Subsidiaries, (v)
     to maintain and keep its properties and the properties of the Noble
     Subsidiaries in as good a repair and condition as presently exists, except
     for deterioration due to ordinary wear and tear and damage due to casualty,
     and (vi) to maintain in full force and effect insurance comparable in
     amount and scope of coverage to that currently maintained by it and the
     Noble Subsidiaries;
 
          (d) Noble shall not make or agree to make, or permit any of the Noble
     Subsidiaries to make or agree to make, any capital expenditure other than
     as previously disclosed in the Noble Commission Filings or those made in
     the ordinary course of business and consistent with past practice;
 
          (e) neither Noble nor any of the Noble Subsidiaries shall take, and
     Noble will use its reasonable efforts to prevent any affiliate of Noble
     from taking, any action that, in the judgment of Arthur Andersen
 
                                       19
<PAGE>   110
 
     & Co., Noble's independent auditors, would cause the Merger not to be
     treated as a "pooling of interests" for accounting purposes;
 
          (f) Noble shall, and shall cause the Noble Subsidiaries to, perform
     their respective obligations under any contracts and agreements to which
     any of them is a party or to which any of their assets is subject, except
     to the extent such failure to perform would not have a material adverse
     effect on Noble and the Noble Subsidiaries, taken as a whole, and except
     for such obligations as Noble or the Noble Subsidiaries in good faith may
     dispute; and
 
          (g) Noble shall not, and shall not permit any of the Noble
     Subsidiaries to, take any action that would, or that reasonably could be
     expected to, result in any of the representations and warranties set forth
     in this Agreement becoming untrue or any of the conditions to the Merger
     set forth in Article VI not being satisfied. Noble promptly shall advise
     Chiles orally and in writing of any change or event having, or which,
     insofar as reasonably can be foreseen, would have, a material adverse
     effect on Noble and the Noble Subsidiaries, taken as a whole.
 
     4.2 Joint Proxy Statement. Promptly after the date of this Agreement, Noble
shall cooperate with Chiles in preparing and shall file with the Commission
under the Exchange Act, and shall use its reasonable efforts to have cleared by
the Commission, the Proxy Statement with respect to the meeting of the
stockholders of Noble referred to in Section 4.3. Noble agrees that the Proxy
Statement (except with respect to information concerning Chiles and the Chiles
Subsidiaries furnished by or on behalf of Chiles specifically for use therein,
for which information Chiles shall be responsible) will comply as to form in all
material respects with the requirements of the Exchange Act and the respective
rules and regulations adopted thereunder, and the Proxy Statement (except with
respect to information concerning Chiles and the Chiles Subsidiaries furnished
by or on behalf of Chiles specifically for use therein, for which information
Chiles shall be responsible) will not contain any untrue statement of a material
fact or omit to state any material fact required to be stated therein or
necessary to make the statements therein not misleading. The Proxy Statement
shall contain the recommendation of the Board of Directors of Noble that the
stockholders of Noble vote to adopt the Noble Charter Amendment and approve this
Agreement. Noble will advise Chiles promptly in writing if prior to the
Effective Time it shall obtain knowledge of any facts that would make it
necessary to amend or supplement the Proxy Statement in order to make the
statements therein not misleading or to comply with applicable law.
 
     4.3 Meeting of Stockholders of Noble. Noble shall promptly take all action
reasonably necessary in accordance with the DGCL and the Noble Certificate and
bylaws to convene a meeting of its stockholders to consider and vote upon the
adoption of the Noble Charter Amendment and approval of this Agreement. The
Board of Directors of Noble (i) shall recommend at such meeting that the
stockholders of Noble vote to adopt and approve the matters referenced in the
preceding sentence; (ii) shall use its reasonable efforts to solicit from
stockholders of Noble proxies in favor of such adoption and approval; and (iii)
shall take all other action reasonably necessary to secure a vote of its
stockholders in favor of such adoption and approval.
 
     4.4 Registration Statement. Promptly after the date of this Agreement,
Noble will file a registration statement (the "Registration Statement") on Form
S-4 with the Commission under the Securities Act with respect to the offering,
sale and delivery of the shares of Noble Common Stock and $1.50 Noble Preferred
Stock to be issued pursuant to the Merger; and Noble will use its reasonable
efforts to cause such Registration Statement to become effective as soon as
practicable after filing. Noble agrees that the Registration Statement (except
with respect to information concerning Chiles and the Chiles Subsidiaries
furnished by or on behalf of Chiles specifically for use therein, for which
information Chiles shall be responsible) will comply as to form in all material
respects with the requirements of the Securities Act and the Exchange Act and
the respective rules and regulations adopted thereunder, and will not contain
any untrue statement of any material fact or omit to state any material fact
required to be stated therein or necessary to make the statements made therein
not misleading. Noble will advise Chiles in writing if prior to the Effective
Time it shall obtain knowledge of any fact that would, in its opinion, make it
necessary to amend or supplement the Registration Statement in order to make the
statements therein not misleading or to comply with applicable law.
 
                                       20
<PAGE>   111
 
     4.5 Reservation of Noble Stock. Subject to adoption by the stockholders of
Noble of the Noble Charter Amendment, Noble shall reserve for issuance, out of
its authorized but unissued capital stock, such number of shares of Noble Common
Stock and $1.50 Noble Preferred Stock as may be issuable upon consummation of
the Merger and such number of shares of Noble Common Stock as may be issuable
upon conversion of the $1.50 Noble Preferred Stock.
 
     4.6 Stock Exchange Listing. Subject to the adoption by the stockholders of
Noble of the Noble Charter Amendment, Noble shall use all reasonable efforts to
cause the shares of Noble Common Stock and $1.50 Noble Preferred Stock to be
issued in the Merger, the shares of Noble Common Stock to be reserved for
issuance upon the exercise of Chiles Options to be assumed by Noble in the
Merger, if any, and the shares of Noble Common Stock issuable upon conversion of
the $1.50 Noble Preferred Stock to be approved for listing on the NASDAQ
National Market System, subject to official notice of issuance, prior to the
Closing Date.
 
     4.7 Affiliates' Agreements. Noble shall use its reasonable efforts to cause
each person whom it believes is an "affiliate" of Noble within the meaning
thereof under Rule 405 under the Securities Act, to deliver to Noble on or prior
to the Closing Date a written agreement substantially in the form of Exhibit B
hereto.
 
     4.8 Registration Rights Agreement. At (and subject to the occurrence of)
the Closing, Noble agrees to execute and deliver a Registration Rights Agreement
to P.A.J.W. Corporation in substantially the form attached hereto as Exhibit F.
 
                                   ARTICLE V
 
                             ADDITIONAL AGREEMENTS
 
     5.1 Accountants Letters.
 
          (a) Chiles shall use its reasonable efforts to cause Arthur Andersen &
     Co. to deliver a letter dated as of the date of the Proxy Statement, and
     addressed to itself and Noble, in form and substance reasonably
     satisfactory to Noble and customary in scope and substance for agreed upon
     procedures letters delivered by independent public accountants in
     connection with registration statements and proxy statements similar to the
     Registration Statement and Proxy Statement.
 
          (b) Noble shall use its reasonable efforts to cause Arthur Andersen &
     Co. to deliver a letter dated as of the date of the Proxy Statement, and
     addressed to itself and Chiles, in form and substance reasonably
     satisfactory to Chiles and customary in scope and substance for agreed upon
     procedures letters delivered by independent public accountants in
     connection with registration statements and proxy statements similar to the
     Registration Statement and Proxy Statement.
 
     5.2 Filings; Consents; Reasonable Efforts. Subject to the terms and
conditions of this Agreement, Chiles and Noble shall (i) make all necessary
filings with respect to the Merger and this Agreement under the HSR Act, the
Securities Act, the Exchange Act and applicable blue sky or similar securities
laws and shall use all reasonable efforts to obtain required approvals and
clearances with respect thereto; (ii) obtain all consents, waivers, approvals,
authorizations and orders required in connection with the authorization,
execution and delivery of this Agreement and the consummation of the Merger; and
(iii) take, or cause to be taken, all appropriate action, and do, or cause to be
done, all things necessary, proper or advisable to consummate and make effective
as promptly as practicable the transactions contemplated by this Agreement.
 
     5.3 Notification of Certain Matters. Chiles shall give prompt notice to
Noble, and Noble shall give prompt notice to Chiles, orally and in writing, of
(i) the occurrence, or failure to occur, of any event which occurrence or
failure would be likely to cause any representation or warranty contained in
this Agreement to be untrue or inaccurate at any time from the date hereof to
the Effective Time, and (ii) any material failure of Chiles or Noble, as the
case may be, or any officer, director, employee or agent thereof, to comply with
or satisfy any covenant, condition or agreement to be complied with or satisfied
by it hereunder.
 
     5.4 Agreement to Defend. In the event any claim, action, suit,
investigation or other proceeding by any governmental body or other person or
other legal or administrative proceeding is commenced that questions
 
                                       21
<PAGE>   112
 
the validity or legality of the transactions contemplated hereby or seeks
damages in connection therewith, the parties hereto agree to cooperate and use
their reasonable efforts to defend against and respond thereto.
 
     5.5 Expenses. Whether or not the Merger is consummated, all costs and
expenses incurred in connection with this Agreement and the transactions
contemplated hereby shall be paid by the party incurring such expense, except
that expenses incurred in connection with printing and mailing the Registration
Statement and the Proxy Statement shall be shared equally by Noble and Chiles;
provided, however, that if this Agreement shall have been terminated pursuant to
Section 7.1 as a result of the willful breach by a party of any of its
representations, warranties, covenants or agreements set forth in this
Agreement, such breaching party shall pay the costs and expenses of the other
parties in connection with the transactions contemplated by this Agreement.
 
     5.6 Noble's Board of Directors. Noble's Board of Directors will take action
to increase the number of directors comprising the full Board of Directors of
Noble at the Effective Time to nine persons and the directors of Noble shall
elect two persons designated by Chiles to fill the two vacancies created by the
increase in the number of directors prior to the Effective Time. The designees
of Chiles shall be as set forth in Part I of Exhibit C. If, prior to the
Effective Time, any such designees shall decline or be unable to serve, Chiles
shall designate another person to serve in such person's stead in accordance
with the provisions of Part II of Exhibit C.
 
     5.7 Indemnification.
 
          (a) From and after the Effective Time, Noble and the Surviving
     Corporation shall, to the fullest extent permitted under applicable law,
     indemnify, defend and hold harmless each person who is now, or has been at
     any time prior to the date hereof or who becomes prior to the Effective
     Time, an officer, director or employee of Chiles or any of the Chiles
     Subsidiaries (the "Indemnified Parties") against all losses, claims,
     damages, costs, expenses, liabilities or judgments or amounts that are paid
     in settlement with the approval of the indemnifying party (which approval
     shall not be unreasonably withheld) of or in connection with any claim,
     action, suit, proceeding or investigation based in whole or in part on or
     arising in whole or in part out of the fact that such person is or was a
     director, officer or employee of Chiles or any of the Chiles Subsidiaries,
     whether pertaining to any matter existing or occurring at or prior to the
     Effective Time and whether reasserted or claimed prior to, or at or after,
     the Effective Time ("Indemnified Liabilities"), including without
     limitation all Indemnified Liabilities based in whole or in part on, or
     arising in whole or in part out of, or pertaining to this Agreement or the
     transactions contemplated hereby, AND SPECIFICALLY INCLUDING ANY
     INDEMNIFIED LIABILITY THAT MAY BE BASED ON THE SOLE OR CONTRIBUTORY
     NEGLIGENCE (WHETHER ACTIVE, PASSIVE, OR GROSS) OF ANY INDEMNIFIED PARTY, in
     each case to the full extent such corporations are permitted under the DGCL
     to indemnify their own directors, officers and employees, as the case may
     be (and the Surviving Corporation or Noble will pay expenses in advance of
     the final disposition of any such action or proceeding to each Indemnified
     Party to the full extent permitted by law). The defense of any such claim,
     action, suit, proceeding or investigation shall be conducted by Noble. If
     Noble has failed to conduct such defense, the Indemnified Parties may
     retain counsel satisfactory to them and the Surviving Corporation shall pay
     all reasonable fees and expenses of such counsel for the Indemnified
     Parties promptly as statements therefor are received. The party not
     conducting the defense will use reasonable efforts to assist in the
     vigorous defense of any such matter, provided that such party shall not be
     liable for any settlement of any claim effected without its written
     consent, which consent, however, shall not be unreasonably withheld. Any
     Indemnified Party wishing to claim indemnification under this Section 5.7,
     upon learning of any such claim, action, suit, proceeding or investigation,
     shall notify Noble (but the failure so to notify a party shall not relieve
     such party from any liability which it may have under this Section 5.7
     except to the extent such failure materially prejudices such party). If
     Noble and the Surviving Corporation are responsible for the attorneys' fees
     of the Indemnified Parties, then the Indemnified Parties as a group may
     retain only one law firm to represent them with respect to each such matter
     unless there is, under applicable standards of professional conduct, a
     conflict on any significant issue between the positions of any two or more
     Indemnified Parties.
 
                                       22
<PAGE>   113
 
          (b) The Surviving Corporation shall purchase and maintain for a period
     of six years after the Effective Time continuation coverage for Chiles's
     directors' and officers' liability insurance policy as in effect on the
     date hereof or obtain a directors' and officers' insurance policy with
     comparable coverage.
 
          (c) The provisions of this Section 5.7 are intended to be for the
     benefit of, and shall be enforceable by, the parties hereto and each
     Indemnified Party, his heirs and his representatives.
 
     5.8 Chiles Employee Benefits.
 
          (a) After the Effective Time, Noble shall provide those employees of
     Chiles and the Chiles Subsidiaries covered by the benefit plans of Chiles
     and the Chiles Subsidiaries with the same benefits in respect of future
     service that accrue in respect of future services to the employees of Noble
     who are employed in comparable positions. Noble and Chiles further agree
     that any present employees of Chiles and the Chiles Subsidiaries shall be
     credited for their service with Chiles for purposes of eligibility, benefit
     entitlement and vesting in the plans provided by Noble (other than for
     purposes of benefit accruals under any defined benefit pension plan). Those
     employees' benefits under Noble's medical benefit plan shall not be subject
     to any exclusions for any pre-existing conditions, and credit shall be
     received for any deductibles or out-of-pocket amounts previously paid.
 
          (b) The provisions of this Section 5.8 are intended to be for the
     benefit of, and shall be enforceable by, the parties hereto and each
     employee of Chiles or any of the Chiles Subsidiaries covered by benefit
     plans of Chiles or a Chiles Subsidiary.
 
     5.9 Post-Effective Time Mailing. As soon as practicable following the
Effective Time, Noble will cause to be mailed to each holder of certificates
that represented Shares immediately prior to the Effective Time, at such
holder's address as it appears on Chiles's stock transfer records, a letter of
transmittal and other information advising such holder of the consummation of
the Merger along with information and instructions to enable such holder to
effect the exchange of stock certificates as contemplated by Article I of this
Agreement.
 
     5.10 Tax Opinion. Noble covenants and agrees that during the two year
period following the Merger it will not cause or permit the Surviving
Corporation to sell or otherwise dispose of assets of Chiles vested in the
Surviving Corporation other than in the ordinary course of business having a
fair market value in excess of 10% of the fair market value of the net assets or
30% of the fair market value of the gross assets of Chiles as of the Effective
Time without first obtaining an opinion of counsel that such sale or disposition
will not affect the qualification of the Merger as a reorganization within the
meaning of Section 368(a) of the Code.
 
     5.11 Chiles Stock Options.
 
          (a) Chiles covenants and agrees to use its best efforts to take all
     action necessary to provide for the exchange of the Chiles Options for
     shares of Noble Common Stock as described in this Section 5.11(a),
     including, but not limited to, making any necessary amendments to the
     Chiles 1990 Plan and obtaining the consent of each holder of the Chiles
     Options to the exchange of such holder's options. Subject to obtaining the
     consent of each holder of the Chiles Options, and further subject to the
     consummation of the Merger and effective at the Effective Time, all then
     outstanding Chiles Options shall be cancelled in exchange for shares of
     Noble Common Stock. If all the currently outstanding Chiles Options remain
     outstanding immediately prior to the Effective Time, then such options
     shall be cancelled in exchange for an aggregate of 480,000 shares of Noble
     Common Stock. If any currently outstanding Chiles Options are exercised
     prior to the Effective Time, then the aggregate number of shares of Noble
     Common Stock specified in the immediately preceding sentence shall be
     reduced based on a formula that ascribes to such exercised option a
     proportionate value of the value of all the currently outstanding Chiles
     Options. The number of shares of Noble Common Stock to be received by each
     holder of a Chiles Option shall be based on a formula that provides that
     all holders of Chiles Options having the same exercise price per share and
     vesting schedule shall receive the same number of shares of Noble Common
     Stock per share of Chiles Common Stock purchasable under such Chiles
     Options.
 
                                       23
<PAGE>   114
 
          (b) If the consent to the exchange described in Section 5.11(a) by
     each of the holders of Chiles Options has not been obtained by Chiles prior
     to the Closing Date, then, in order to preserve that the Merger be treated
     as a "pooling of interests" for accounting purposes, the Chiles Options
     shall not be exchanged as provided in Section 5.11(a) and Noble will take
     such action as is necessary to assume, effective at the Effective Time,
     each Chiles Option that remains as of such time unexercised in whole or in
     part and to substitute shares of Noble Common Stock as purchasable under
     each such assumed option ("Assumed Option"), with such assumption and
     substitution to be effected as follows:
 
             (i) The Assumed Option shall not give the optionee additional
        benefits which he did not have under the Chiles Option before such
        assumption and shall be assumed on the same terms and conditions,
        including, without limitation, vesting schedule, as the Chiles Options
        being assumed, subject to Section 5.11(b)(ii) and (iii);
 
             (ii) The number of shares of Noble Common Stock purchasable under
        the Assumed Option shall be equal to the number of shares of Noble
        Common Stock that the holder of the Chiles Option being assumed would
        have received (without regard to any vesting schedule) upon consummation
        of the Merger had such Chiles Option been exercised in full immediately
        prior to consummation of the Merger; and
 
             (iii) The per share exercise price of such Assumed Option shall be
        an amount equal to the per share exercise price of the Chiles Option
        being assumed divided by 0.75.
 
          (c) If the Chiles Options are assumed by Noble pursuant to Section
     5.11(b), Noble shall take all corporate action necessary to reserve for
     issuance a sufficient number of shares of Noble Common Stock for delivery
     upon exercise of the Assumed Options, and, as soon as practicable after the
     Effective Time, Noble shall file a registration statement on Form S-8 (or
     other appropriate form) with respect to the shares of Noble Common Stock
     subject to the Assumed Options, and shall use its best efforts to maintain
     the effectiveness of such registration statement (and maintain the current
     status of any prospectus contained therein) for so long as any of the
     Assumed Options remain outstanding.
 
     5.12 Designation of $1.50 Noble Preferred Stock. Noble agrees to take such
action prior to the Effective Time, including the filing of a certificate of
designations with the Secretary of State of Delaware, to establish and create a
new series of Noble preferred stock designated the "$1.50 Convertible Preferred
Stock" from its authorized but unissued shares of preferred stock and having
substantially the same rights, privileges, preferences and voting power as
shares of Chiles Preferred Stock. The shares of $1.50 Noble Preferred Stock
issuable pursuant to the Merger to holders of Chiles Preferred Stock shall be
convertible into the consideration received by holders of Chiles Common Stock at
the Conversion Price (as defined in the certificate of designations of the
Chiles Preferred Stock) immediately after the Effective Time. The shares of
$1.50 Noble Preferred Stock and the shares of $2.25 Noble Preferred Stock shall
rank on a parity with each other in respect of the payment of dividends and upon
liquidation, dissolution or winding up of Noble.
 
                                   ARTICLE VI
 
                                   CONDITIONS
 
     6.1 Conditions to Obligation of Each Party to Effect the Merger. The
respective obligations of each party to effect the Merger shall be subject to
the fulfillment at or prior to the Closing Date of the following conditions:
 
          (a) This Agreement and the Noble Charter Amendment shall have been
     approved and adopted by the requisite vote of the stockholders of Noble,
     and this Agreement shall have been approved and adopted by the requisite
     vote of the stockholders of Chiles, as may be required by law, by the rules
     of the NASDAQ National Market System and the American Stock Exchange,
     respectively, and by any applicable provisions of their respective
     certificates of incorporation or bylaws;
 
          (b) The waiting period (and any extension thereof) applicable to the
     consummation of the Merger under the HSR Act shall have expired or been
     terminated;
 
                                       24
<PAGE>   115
 
          (c) No order shall have been entered and remain in effect in any
     action or proceeding before any foreign, federal or state court or
     governmental agency or other foreign, federal or state regulatory or
     administrative agency or commission that would prevent or make illegal the
     consummation of the Merger;
 
          (d) The Registration Statement shall be effective on the Closing Date,
     and all post-effective amendments filed shall have been declared effective
     or shall have been withdrawn; and no stop-order suspending the
     effectiveness thereof shall have been issued and no proceedings for that
     purpose shall have been initiated or, to the knowledge of the parties,
     threatened by the Commission;
 
          (e) There shall have been obtained any and all material permits,
     approvals and consents of securities or blue sky commissions of any
     jurisdiction, and of any other governmental body or agency, that reasonably
     may be deemed necessary so that the consummation of the Merger and the
     transactions contemplated thereby will be in compliance with applicable
     laws, the failure to comply with which would have a material adverse effect
     on the business, financial condition or results of operations of Noble, the
     Surviving Corporation and their subsidiaries, taken as a whole after
     consummation of the Merger;
 
          (f) The shares of Noble Common Stock and $1.50 Noble Preferred Stock
     issuable upon consummation of the Merger and the shares of Noble Common
     Stock issuable upon conversion of the $1.50 Noble Preferred Stock or upon
     exercise of any Assumed Options shall have been approved for listing on the
     NASDAQ National Market System, subject to official notice of issuance;
 
          (g) All approvals of private persons or corporations, (i) the granting
     of which is necessary for the consummation of the Merger or the
     transactions contemplated in connection therewith and (ii) the non-receipt
     of which would have a material adverse effect on the business, financial
     condition or results of operations of Noble, the Surviving Corporation and
     their subsidiaries, taken as a whole after the consummation of the Merger,
     shall have been obtained; and
 
          (h) Noble and Chiles shall have been advised in writing on the Closing
     Date by Arthur Andersen & Co. that, in accordance with generally accepted
     accounting principles, the Merger should be treated as a "pooling of
     interests" for accounting purposes.
 
     6.2 Additional Conditions to Obligations of Noble. The obligation of Noble
to effect the Merger is, at the option of Noble, also subject to the fulfillment
at or prior to the Closing Date of the following conditions:
 
          (a) The representations and warranties of Chiles contained in Section
     2.2 shall be accurate in all material respects as of the date of this
     Agreement and (except to the extent such representations and warranties
     speak specifically as of an earlier date) as of the Closing Date as though
     such representations and warranties had been made at and as of that time;
     all of the terms, covenants and conditions of this Agreement to be complied
     with and performed by Chiles on or before the Closing Date shall have been
     duly complied with and performed in all material respects; and a
     certificate to the foregoing effect dated the Closing Date and signed by
     the chief executive officer of Chiles shall have been delivered to Noble;
 
          (b) Since the date of this Agreement, no material adverse change in
     the financial condition, results of operations or business of Chiles and
     the Chiles Subsidiaries, taken as a whole, shall have occurred, and Chiles
     and the Chiles Subsidiaries shall not have suffered any damage, destruction
     or loss materially adversely affecting the properties or business of Chiles
     and the Chiles Subsidiaries, taken as a whole, and Noble shall have
     received a certificate signed by the chief executive officer of Chiles
     dated the Closing Date to such effect;
 
          (c) The Board of Directors of Noble shall have received from Simmons &
     Company International, financial advisor to Noble, a written opinion, dated
     as of the date of this Agreement, satisfactory in form and substance to the
     Board of Directors of Noble, to the effect that (i) the conversion ratio of
     0.75 of a share of Noble Common Stock to be issued for each share of Chiles
     Common Stock and (ii) the conversion ratio of one share of $1.50 Noble
     Preferred Stock to be issued for each share of Chiles Preferred Stock, in
     each case pursuant to the Merger, is fair to the stockholders of Noble from
     a financial
 
                                       25
<PAGE>   116
 
     point of view, which opinion shall have been confirmed in writing to
     such Board as of the date the Proxy Statement is first mailed to the
     stockholders of Noble and not subsequently withdrawn;
 
          (d) Chiles shall have received, and furnished written copies to Noble
     of, the Chiles affiliates' agreements pursuant to Section 3.5;
 
          (e) Noble shall have received from Vinson & Elkins L.L.P., counsel to
     Chiles, an opinion dated the Closing Date covering the matters set forth in
     Exhibit D;
 
          (f) Noble shall have received from Thompson & Knight, P.C. a written
     opinion dated as of the date that the Proxy Statement is first mailed to
     stockholders of Noble to the effect that (i) the Merger will be treated for
     U.S. federal income tax purposes as a reorganization within the meaning of
     Section 368(a) of the Code, (ii) Noble, Sub and Chiles will each be a party
     to that reorganization within the meaning of Section 368(b) of the Code,
     and (iii) Noble, Sub and Chiles shall not recognize any gain or loss for
     U.S. federal income tax purposes as a result of the Merger, and such
     opinion shall not have been withdrawn or modified in any material respect;
 
          (g) The Shareholder Voting Agreement dated April 23, 1990, as amended
     on May 24, 1991, among P.A.J.W. Corporation, OMI Investments, Inc., AWILCO
     Shipping and WILCO A/S shall have been terminated or shall terminate by its
     terms as of the Effective Time; and
 
          (h) Chiles and its agent in Nigeria, Hydrocarbon Services of Nigeria
     ("HSN"), shall have executed any documentation necessary to the reasonable
     satisfaction of Noble to permit the export of the drilling rigs of Chiles
     that have been imported by HSN and Chiles into Nigeria.
 
     6.3 Additional Conditions to Obligations of Chiles. The obligation of
Chiles to effect the Merger is, at the option of Chiles, also subject to the
fulfillment at or prior to the Closing Date of the following conditions:
 
          (a) The representations and warranties of Noble and Sub contained in
     Section 2.1 shall be accurate in all material respects as of the date of
     this Agreement and (except to the extent such representations and
     warranties speak specifically as of an earlier date) as of the Closing Date
     as though such representations and warranties had been made at and as of
     that time; all the terms, covenants and conditions of this Agreement to be
     complied with and performed by Noble on or before the Closing Date shall
     have been duly complied with and performed in all material respects; and a
     certificate to the foregoing effect dated the Closing Date and signed by
     the chief executive officer of Noble shall have been delivered to Chiles;
 
          (b) Since the date of this Agreement, no material adverse change in
     the results of operations, financial condition or business of Noble and the
     Noble Subsidiaries, taken as a whole, shall have occurred, and Noble and
     the Noble Subsidiaries shall not have suffered any damage, destruction or
     loss materially adversely affecting the properties or business of Noble and
     the Noble Subsidiaries, taken as a whole, and Chiles shall have received a
     certificate signed by the chief executive officer of Noble dated the
     Closing Date to such effect;
 
          (c) Chiles shall have received from Salomon Brothers Inc, financial
     advisor to Chiles, a written opinion, dated as of the date of this
     Agreement, satisfactory in form and substance to the Board of Directors of
     Chiles, to the effect that (i) the conversion ratio of 0.75 of a share of
     Noble Common Stock to be issued for each share of Chiles Common Stock and
     (ii) the conversion ratio of one share of $1.50 Noble Preferred Stock to be
     issued for each share of Chiles Preferred Stock, in each case pursuant to
     the Merger, is fair to the common and preferred stockholders of Chiles from
     a financial point of view, which opinion shall have been confirmed in
     writing to such Board as of the date the Proxy Statement is first mailed to
     the stockholders of Chiles and not subsequently withdrawn;
 
          (d) The Board of Directors of Noble shall have taken such action as
     may be necessary to elect the persons designated by Chiles on or pursuant
     to Exhibit C to the Noble Board of Directors effective as of the Effective
     Time;
 
                                       26
<PAGE>   117
 
          (e) Chiles shall have received from Thompson & Knight, P.C., counsel
     to Noble, an opinion dated the Closing Date covering the matters set forth
     in Exhibit E;
 
          (f) Noble shall have received, and furnished copies to Chiles of, the
     Noble affiliates' agreements pursuant to Section 4.7; and
 
          (g) Chiles shall have received from Vinson & Elkins L.L.P., a written
     opinion dated as of the date that the Proxy Statement is first mailed to
     stockholders of Chiles to the effect that (i) the Merger will be treated
     for U.S. federal income tax purposes as a reorganization within the meaning
     of Section 368(a) of the Code; (ii) Noble, Sub and Chiles will each be a
     party to that reorganization within the meaning of Section 368(b) of the
     Code; and (iii) the stockholders of Chiles shall not recognize any gain or
     loss for U.S. federal income tax purposes as a result of the Merger, other
     than to the extent such stockholders receive cash in lieu of fractional
     shares, and such opinion shall not have been withdrawn or modified in any
     material respect.
 
                                  ARTICLE VII
 
                                 MISCELLANEOUS
 
     7.1 Termination. This Agreement may be terminated and the Merger and the
other transactions contemplated herein may be abandoned at any time prior to the
Effective Time, whether prior to or after approval by the stockholders of Noble
or the stockholders of Chiles:
 
          (a) by mutual consent of Noble and Chiles;
 
          (b) by either Noble or Chiles if the Merger has not been effected on
     or before January 31, 1995;
 
          (c) by Noble if the condition set forth in Section 6.2(c) is not
     satisfied;
 
          (d) by Chiles if the condition set forth in Section 6.3(c) is not
     satisfied;
 
          (e) by either Noble or Chiles if a final, unappealable order of a
     judicial or administrative authority of competent jurisdiction to restrain,
     enjoin or otherwise prevent a consummation of this Agreement or the
     transactions contemplated in connection herewith shall have been entered;
 
          (f) by either Noble or Chiles if the required approval of the
     stockholders of Chiles or the stockholders of Noble provided for in
     Sections 3.3 and 4.3, respectively, is not received in a vote duly taken at
     their respective stockholders' meetings;
 
          (g) by Noble if (i) since the date of this Agreement there has been a
     material adverse change in the results of operations, financial condition
     or business of Chiles and the Chiles Subsidiaries, taken as a whole, or
     (ii) there has been a material breach of any representation or warranty or
     covenant set forth in this Agreement by Chiles which breach has not been
     cured within five business days following receipt by Chiles of notice of
     such breach;
 
          (h) by Chiles if (i) since the date of this Agreement there has been a
     material adverse change in the results of operations, financial condition
     or business of Noble and the Noble Subsidiaries, taken as a whole, or (ii)
     there has been a material breach of any representation or warranty or
     covenant set forth in this Agreement by Noble which breach has not been
     cured within five business days following receipt by Noble of notice of
     such breach; or
 
          (i) by Noble if the Board of Directors of Chiles exercises its right
     pursuant to Section 3.4 not to convene a meeting of the Chiles
     stockholders.
 
     7.2 Effect of Termination.
 
          (a) In the event of any termination of this Agreement pursuant to
     Section 7.1, (i) the provisions of the Confidentiality Agreements (as
     defined below) and the provisions of Section 5.5 shall survive any such
     termination, and (ii) such termination shall not relieve any party from
     liability for any breach of this Agreement.
 
                                       27
<PAGE>   118
 
          (b) In the event that either Noble or Chiles terminates this Agreement
     pursuant to Sections 7.1(a), 7.1(b), 7.1(d), 7.1(f), 7.1(g)(ii) or 7.1(i),
     and (i) this Agreement has either not been submitted to the stockholders of
     Chiles or the stockholders of Chiles have declined to approve this
     Agreement by the requisite vote, (ii) after the date of this Agreement but
     at or before the time this Agreement is terminated there shall have been a
     Chiles Acquisition Transaction proposed in writing to Chiles and (iii) any
     Chiles Acquisition Transaction (whether the same or different from the one
     referenced in clause (ii)) is consummated at any time within one year after
     the date of this Agreement, then Chiles shall promptly pay to Noble the sum
     of $6,000,000.
 
          (c) If this Agreement is terminated pursuant to Section 7.1(f) because
     of the failure of Noble to secure the approval of its stockholders as
     required under Section 4.3 and the conditions to closing set forth in
     Sections 6.1 and 6.2 (other than Sections 6.1(f), 6.1(h), 6.2(d), 6.2(e),
     6.2(f), 6.2(g) and 6.2(h)) have otherwise been satisfied, then Noble shall
     promptly, but in no event later than five business days after written
     request by Chiles, pay to Chiles an amount equal to $1,000,000 in
     immediately available funds as reimbursement for an agreed upon estimate of
     Chiles's out-of-pocket fees and expenses incurred in connection with the
     transactions contemplated hereby.
 
          (d) If this Agreement is terminated pursuant to Section 7.1(f) because
     of the failure of Chiles to secure the approval of its stockholders as
     required under Section 3.3 and the conditions to closing set forth in
     Sections 6.1 and 6.3 (other than Sections 6.1(f), 6.1(h), 6.3(d), 6.3(e),
     6.3(f), and 6.3(g)) have otherwise been satisfied, then Chiles shall
     promptly, but in no event later than five business days after written
     request by Noble, pay to Noble an amount equal to $1,000,000 in immediately
     available funds as reimbursement for an agreed upon estimate of Noble's
     out-of-pocket fees and expenses incurred in connection with the
     transactions contemplated hereby; provided, however, that if Chiles shall
     be obligated to make any payment to Noble pursuant to Section 7.2(b), then
     Chiles shall be entitled to offset from any amount due under Section 7.2(b)
     any amount paid to Noble pursuant to this Section 7.2(d).
 
     7.3 Waiver and Amendment. Any provision of this Agreement may be waived at
any time by the party that is, or whose stockholders are, entitled to the
benefits thereof. This Agreement may not be amended or supplemented at any time,
except by an instrument in writing signed on behalf of each party hereto,
provided that after this Agreement has been approved and adopted by the
stockholders of Noble and Chiles, this Agreement may be amended only as may be
permitted by applicable provisions of the DGCL. The waiver by any party hereto
of any condition or of a breach of another provision of this Agreement shall not
operate or be construed as a waiver of any other condition or subsequent breach.
The waiver by any party hereto of any of the conditions precedent to its
obligations under this Agreement shall not preclude it from seeking redress for
breach of this Agreement other than with respect to the condition so waived.
 
     7.4 Nonsurvival of Representations, Warranties and Agreements. None of the
representations, warranties, covenants or agreements in this Agreement or in any
instrument delivered pursuant to this Agreement shall survive the Effective
Time, except for the terms of Article I, the second paragraph of Section 2.1(i),
the third, fourth and fifth sentences of the second paragraph of Section 2.2(i),
Sections 5.7, 5.8, 5.10 and 5.11, Article VII, and the agreements of the
"affiliates" of Chiles and Noble delivered pursuant to Sections 3.5 and 4.7,
respectively hereof.
 
     7.5 Public Statements. Chiles and Noble agree to consult with each other
prior to issuing any press release or otherwise making any public statement with
respect to the transactions contemplated hereby, and shall not issue any such
press release or make any such public statement prior to such consultation,
except as may be required by law or applicable stock exchange policy.
 
     7.6 Assignment. This Agreement shall inure to the benefit of and will be
binding upon the parties hereto and their respective legal representatives,
successors and permitted assigns. Except as set forth in this Agreement, this
Agreement shall not be assignable by the parties hereto.
 
                                       28
<PAGE>   119
 
     7.7 Notices. All notices, requests, demands, claims and other
communications which are required to be or may be given under this Agreement
shall be in writing and shall be deemed to have been duly given if (i) delivered
in person or by courier, (ii) sent by telecopy or facsimile transmission, answer
back requested, or (iii) mailed, certified first class mail, postage prepaid,
return receipt requested, to the parties hereto at the following addresses:
 
<TABLE>
<S>               <C>
if to Chiles:     Chiles Offshore Corporation
                  1400 Broadfield Blvd., Suite 400
                  Houston, Texas 77084-5133
                  Attention: C. Ray Bearden

with a copy to:   Vinson & Elkins L.L.P.
                  2500 First City Tower
                  Houston, Texas 77002-6760
                  Attention: Keith R. Fullenweider

if to Noble:      Noble Drilling Corporation
                  10370 Richmond Avenue, Suite 400
                  Houston, Texas 77042
                  Attention: James C. Day

with a copy to:   Thompson & Knight, P.C.
                  1700 Pacific Avenue, Suite 3300
                  Dallas, Texas 75201
                  Attention: Robert D. Campbell
</TABLE>
 
or to such other address as any party shall have furnished to the other by
notice given in accordance with this Section 7.7. Such notices shall be
effective, (i) if delivered in person or by courier, upon actual receipt by the
intended recipient, (ii) if sent by telecopy or facsimile transmission, when the
answer back is received, or (iii) if mailed, upon the earlier of five days after
deposit in the mail and the date of delivery as shown by the return receipt
therefor.
 
     7.8 Governing Law. This Agreement shall be governed by and construed in
accordance with the substantive law of the State of Texas without giving effect
to the principles of conflicts of law thereof.
 
     7.9 Severability. If any term, provision, covenant or restriction of this
Agreement is held by a court of competent jurisdiction to be invalid, void or
unenforceable, the remainder of the terms, provision, covenants and restrictions
of this Agreement shall continue in full force and effect and shall in no way be
affected, impaired or invalidated.
 
     7.10 Counterparts. This Agreement may be executed in counterparts, each of
which shall be an original, but all of which together shall constitute one and
the same agreement.
 
     7.11 Headings. The Section headings herein are for convenience only and
shall not affect the construction hereof.
 
     7.12 Confidentiality Agreements. The Confidentiality Agreements entered
into between Noble and Chiles in May 1994 (the "Confidentiality Agreements") are
hereby incorporated by reference herein and made a part hereof.
 
     7.13 Entire Agreement; Third Party Beneficiaries. This Agreement and the
Confidentiality Agreements constitute the entire agreement and supersede all
other prior agreements and understandings, both oral and written, among the
parties or any of them, with respect to the subject matter hereof and neither
this nor any document delivered in connection with this Agreement confers upon
any person not a party hereto any rights or remedies hereunder except as
provided in Sections 5.7, 5.8 and 5.11.
 
     7.14 Disclosure Letters.
 
          (a) The Chiles Disclosure Letter, executed by Chiles as of the date
     hereof, and delivered to Noble on the date hereof, contains all disclosure
     required to be made by Chiles under the various terms and
 
                                       29
<PAGE>   120
 
     provisions of this Agreement. Each item of disclosure set forth in the
     Chiles Disclosure Letter specifically refers to the Article and Section
     of the Agreement to which such disclosure responds, and shall not be
     deemed to be disclosed with respect to any other Article or Section of
     the Agreement.
     
          (b) The Noble Disclosure Letter, executed by Noble as of the date
     hereof, and delivered to Chiles on the date hereof, contains all disclosure
     required to be made by Noble under the various terms and provisions of this
     Agreement. Each item of disclosure set forth in the Noble Disclosure Letter
     specifically refers to the Article and Section of the Agreement to which
     such disclosure responds, and shall not be deemed to be disclosed with
     respect to any other Article or Section of the Agreement.
 
     7.15 Stock Exchange. If any securities of Noble become listed and traded on
the New York Stock Exchange, references herein to the "NASDAQ National Market
System" shall be deemed changed to the "New York Stock Exchange" where the
context so requires; provided that, subject to Section 6.1(f) hereof, there
shall be no obligation on Noble to list the $1.50 Noble Preferred Stock on such
exchange.
 
     IN WITNESS WHEREOF, each of the parties has caused this Agreement to be
executed on its behalf by its officers thereunto duly authorized, all as of the
date first above written.
 
                                            NOBLE DRILLING CORPORATION
 
                                            By:    /s/  JAMES C. DAY
                                                -----------------------------
                                                        JAMES C. DAY
                                                  Chairman, President and
                                                  Chief Executive Officer
 
                                            NOBLE OFFSHORE CORPORATION
 
                                            By: /s/  BYRON L. WELLIVER
                                                -----------------------------
                                                     BYRON L. WELLIVER
                                                         President
 
                                            CHILES OFFSHORE CORPORATION
 
                                            By:   /s/  C. RAY BEARDEN
                                                -----------------------------
                                                       C. RAY BEARDEN
                                                         President
 
                                       30
<PAGE>   121
 
                                                                       EXHIBIT A
 
                          CHILES AFFILIATE'S AGREEMENT
 
Noble Drilling Corporation
10370 Richmond Avenue, Suite 400
Houston, Texas 77042
 
Gentlemen:
 
     I have been advised that as of the date hereof, I may be deemed to be an
"affiliate" of Chiles Offshore Corporation, a Delaware corporation ("Chiles"),
as that term is defined for purposes of paragraphs (c) and (d) of Rule 145 of
the Rules and Regulations (the "Rules and Regulations") of the Securities and
Exchange Commission (the "Commission") under the Securities Act of 1933, as
amended (the "Securities Act").
 
     Pursuant to the terms of the Agreement and Plan of Merger among Noble
Drilling Corporation, a Delaware corporation ("Noble"), Noble Offshore
Corporation, a newly formed Delaware corporation and a wholly-owned subsidiary
of Noble ("Noble Sub"), and Chiles, dated as of June 13, 1994 (the "Merger
Agreement") providing for, among other things, the merger of Chiles with and
into Noble Sub (the "Merger"), I will be entitled to receive shares of Common
Stock, par value $0.10 per share, of Noble ("Noble Stock"), in exchange for the
shares of Common Stock, par value $0.01 per share, of Chiles ("Chiles Common
Stock") owned by me at the effective time of the Merger as determined pursuant
to the Merger Agreement. I understand that the Merger will be treated as a
"pooling of interests" in accordance with generally accepted accounting
principles and that the staff of the Commission has issued certain guidelines
that should be followed to ensure the pooling of the entities.
 
     I hereby represent and warrant that, since 30 days before closing to and
including the date hereof, I have not sold, transferred or otherwise disposed of
any shares of Chiles Common Stock.
 
     In consideration of the agreements contained herein, Noble's reliance on
this letter in connection with the consummation of the Merger and for other good
and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, I hereby represent, warrant and agree that (i) I will not make any
sale, transfer or other disposition of Noble Stock received by me pursuant to
the Merger or otherwise owned by me until such time as financial statements that
include at least 30 days of combined operations of Chiles and Noble after the
Merger shall have been publicly reported, unless I shall have delivered to Noble
prior to any such sale, transfer or other disposition, a written opinion from
Arthur Andersen & Co., independent public accountants for Noble, or a written
no-action letter from the accounting staff of the Commission, in either case in
form and substance reasonably satisfactory to Noble, to the effect that such
sale, transfer or other disposition will not cause the Merger not to be treated
as a "pooling of interests" for accounting purposes, and (ii) I will not make
any sale, transfer or other disposition of any shares of Noble Stock received by
me pursuant to the Merger in violation of the Securities Act or the Rules and
Regulations. I have been advised that the issuance of the shares of Noble Stock
pursuant to the Merger will have been registered with the Commission under the
Securities Act on a Registration Statement on Form S-4. However, I have also
been advised that since I may be deemed to be an affiliate of Chiles at the time
the Merger is submitted for a vote of the stockholders of Chiles, the Noble
Stock received by me pursuant to the Merger can be sold by me only (i) pursuant
to an effective registration statement under the Securities Act, (ii) in
conformity with the volume and other limitations of Rule 145 promulgated by the
Commission under the Securities Act, or (iii) in reliance upon an exemption from
registration that is available under the Securities Act.
 
     I also understand that instructions will be given to Noble's transfer agent
with respect to the Noble Stock to be received by me pursuant to the Merger and
that there will be placed on the certificates representing such shares of Noble
Stock, or any substitutions therefor, a legend stating in substance as follows:
 
     "These shares were issued in a transaction to which Rule 145
     promulgated under the Securities Act of 1933 applies. These shares may
     only be transferred in accordance with the terms of such Rule and an
     Affiliate's Agreement between the original holder of such shares of
     Noble Drilling Corporation, a copy of which agreement is on file at
     the principal offices of Noble Drilling Corporation."
 
                                    Exh. A-1
<PAGE>   122
 
It is understood and agreed that the legend set forth above shall be removed
upon surrender of certificates bearing such legend by delivery of substitute
certificates without such legend if I shall have delivered to Noble an opinion
of counsel, in form and substance reasonably satisfactory to Noble, to the
effect that (i) the sale or disposition of the shares represented by the
surrendered certificates may be effected without registration of the offering,
sale and delivery of such shares under the Securities Act, and (ii) the shares
to be so transferred may be publicly offered, sold and delivered by the
transferee thereof without compliance with the registration provisions of the
Securities Act.
 
     By its execution hereof, Noble agrees that it will, as long as I own any
Noble Stock to be received by me pursuant to the Merger, take all reasonable
efforts to make timely filings with the Commission of all reports required to be
filed by it pursuant to the Securities Exchange Act of 1934, as amended, and
will promptly furnish upon written request of the undersigned a written
statement confirming that such reports have been so timely filed.
 
     If you are in agreement with the foregoing, please so indicate by signing
below and returning a copy of this letter to the undersigned, at which time this
letter shall become a binding agreement between us.
 
                                            Very truly yours,
 
                                            By: ___________________________
                                                Name:
                                                Title:
                                                Date:
                                                Address:
 
ACCEPTED this     day
of             , 1994
 
NOBLE DRILLING CORPORATION
 
By ___________________________
   Name:
   Title:
 
                                    Exh. A-2
<PAGE>   123
 
                                                                       EXHIBIT B
 
                          NOBLE AFFILIATE'S AGREEMENT
 
Noble Drilling Corporation
10370 Richmond Avenue, Suite 400
Houston, Texas 77042
 
Gentlemen:
 
     I have been advised that as of the date hereof, I may be deemed to be an
"affiliate" of Noble Drilling Corporation, a Delaware corporation ("Noble"), as
that term is defined for the purposes of Rule 405 under the Securities Act of
1933, as amended.
 
     Reference is made to the Agreement and Plan of Merger among Noble, Noble
Offshore Corporation, a newly formed Delaware corporation and a wholly-owned
subsidiary of Noble ("Noble Sub"), and Chiles Offshore Corporation, a Delaware
corporation ("Chiles"), dated as of June 13, 1994 (the "Merger Agreement")
providing for, among other things, the merger of Chiles with and into Noble Sub
(the "Merger"), pursuant to which all outstanding shares of Common Stock, $.01
par value per share, of Chiles outstanding immediately prior to the Merger will
be converted into the right to receive 0.75 of a share of Common Stock, $.10 par
value per share, of Noble ("Noble Common Stock"). I understand that the Merger
will be treated as a "pooling of interests" in accordance with generally
accepted accounting principles and that the staff of the Securities and Exchange
Commission (the "Commission") has issued certain guidelines that should be
followed to ensure the pooling of the entities for accounting purposes.
 
     In consideration for the foregoing, I hereby represent and warrant that,
since 30 days before closing to and including the date hereof, I have not sold,
transferred or otherwise disposed of any shares of Noble Common Stock. I further
hereby represent, warrant and agree that I will not make any sale, transfer or
other disposition of Noble Common Stock owned by me until such time as financial
statements that include at least 30 days of combined operations of Chiles and
Noble after the Merger shall have been publicly reported, unless I shall have
delivered to Noble prior to any such sale, transfer or other disposition, a
written opinion from Arthur Andersen & Co., independent public accountants for
Noble, or a written no-action letter from the accounting staff of the
Commission, in either case in form and substance reasonably satisfactory to
Noble, to the effect that such sale, transfer or other disposition will not
cause the Merger not to be treated as a "pooling of interests" for accounting
purposes.
 
                                            Very truly yours,
 
                                            By: ___________________________
                                                Name:
                                                Title:
                                                Date:
 
                                    Exh. B-1
<PAGE>   124
 
                                                                       EXHIBIT C
 
CHILES DESIGNEES:
 
                                     PART I
 
                  NAME                                     TERM
                  ----                                     ----
 
        Marc E. Leland                           through 1997 Annual Meeting of
                                                 Noble Stockholders
 
        Lawrence Chazen                          through 1996 Annual Meeting of
        (subject to approval of nominating       Noble Stockholders
        committee as set forth in Part II    
        below) or, at the option of Chiles,  
        a designee of Chiles determined prior
        to the filing of the Proxy Statement 
        with the Commission, selected in     
        accordance with Part II              
         
        
                                    PART II
 
     Any person that is to be designated by Chiles for election to the Board of
Directors of Noble pursuant to Section 5.6 of the Agreement must be a person
possessing suitable business and educational qualifications and personal
characteristics and must be approved by the nominating committee of the Board of
Directors of Noble in its reasonable discretion.
 
                                    Exh. C-1
<PAGE>   125
 
                                                                       EXHIBIT D
 
     (i) Chiles is a corporation duly incorporated, validly existing and in good
standing under the laws of the State of Delaware and has all requisite corporate
power and authority to carry on its business as now being conducted as described
in the Proxy Statement;
 
     (ii) The certificate of merger prepared for filing with the Secretary of
State of Delaware complies in all material respects with the requirements of the
DGCL, and upon filing of such certificate with the Secretary of State of
Delaware, the Merger will become effective in accordance with the applicable
provisions of the DGCL;
 
     (iii) The affirmative vote of the holders of a majority of the outstanding
shares of Chiles Common Stock is the only vote of the holders of any class or
series of the capital stock of Chiles necessary to approve the Agreement and the
Merger;
 
     (iv) Chiles has the requisite corporate power to merge with and into Sub as
contemplated by the Agreement;
 
     (v) The execution and delivery of the Agreement did not, and the
consummation of the Merger will not, violate any provisions of Chiles's
Certificate of Incorporation or Bylaws; and
 
     (vi) The Agreement has been duly and validly authorized, executed and
delivered by Chiles, and the Agreement is a valid and binding agreement of
Chiles enforceable in accordance with its terms, except as such enforceability
may be limited by bankruptcy, insolvency, reorganization, moratorium or other
similar laws or court decisions affecting creditors' rights generally and by
other general equitable principles.
 
                                    Exh. D-1
<PAGE>   126
 
                                                                       EXHIBIT E
 
     (i) Noble is a corporation duly incorporated, validly existing and in good
standing under the laws of the State of Delaware and has all requisite corporate
power and authority to carry on its business as now being conducted as described
in the Registration Statement;
 
     (ii) The certificate of merger prepared for filing with the Secretary of
State of Delaware complies in all material respects with the requirements of the
DGCL, and upon filing of such certificate with the Secretary of State of
Delaware, the Merger will become effective in accordance with the applicable
provisions of the DGCL;
 
     (iii) The appropriate filings have been made with respect to the Merger to
cause the Merger to become effective with the Secretary of State of the State of
Delaware;
 
     (iv) The affirmative vote of the holders of a majority of the outstanding
shares of Noble Common Stock is the only vote of the holders of any class or
series of the capital stock of Noble necessary to approve the Noble Charter
Amendment; and the affirmative vote of the holders of a majority of the shares
of Noble Common Stock present at the Noble special stockholders' meeting
convened in accordance with Section 4.3 of the Agreement and entitled to vote
thereon is the only vote of the holders of any class or series of the capital
stock of Noble necessary to approve the Agreement;
 
     (v) Sub has the requisite corporate power to merge with Chiles as
contemplated by the Agreement;
 
     (vi) The execution and delivery of the Agreement did not, and the
consummation of the Merger will not, violate any provision of the Certificates
of Incorporation or Bylaws of Noble or Sub;
 
     (vii) The Agreement has been duly and validly authorized, executed and
delivered by Noble and Sub, and the Agreement is a valid and binding agreement
of Noble and Sub enforceable in accordance with its terms, except as such
enforceability may be limited by bankruptcy, insolvency, reorganization,
moratorium or other similar laws or court decisions affecting creditors' rights
generally and by other general equitable principles;
 
     (viii) The Registration Statement has become effective under the Securities
Act and, to the knowledge of such counsel, no stop order suspending the
effectiveness of the Registration Statement has been issued and no proceedings
for such purpose have been initiated or are pending or threatened by the
Commission under the Securities Act; and
 
     (ix) The shares of Noble Common Stock and Noble Preferred Stock to be
delivered in connection with the Merger are duly authorized and reserved for
issuance and, when issued in accordance with the terms and conditions of the
Agreement, will be validly issued, fully paid and nonassessable.
 
                                    Exh. E-1
<PAGE>   127

                                                                       EXHIBIT F


                           NOBLE DRILLING CORPORATION

                         REGISTRATION RIGHTS AGREEMENT


         This REGISTRATION RIGHTS AGREEMENT dated as of _______________, 1994
(this "Agreement") by and between NOBLE DRILLING CORPORATION, a Delaware
corporation (the "Company"), and P.A.J.W. CORPORATION, a Delaware corporation
(the "Stockholder");

                              W I T N E S S E T H:

         WHEREAS, the Stockholder is the holder of 11,535,587 shares of the
common stock, par value $0.01 per share, of Chiles Offshore Corporation, a
Delaware corporation ("COC"), constituting approximately 30.3% of the currently
outstanding shares of such class of stock;

         WHEREAS, the Company, Noble Offshore Corporation, a newly formed,
wholly-owned subsidiary of the Company ("Sub"), and COC are parties to that
certain Agreement and Plan of Merger dated as of June 13, 1994 (the "Merger
Agreement") pursuant to which COC will be merged with and into Sub (the
"Merger") and all of the issued and outstanding capital stock of COC will be
converted into the right to receive capital stock of the Company (and cash in
lieu of fractional shares of common stock of the Company);

         WHEREAS, the ability of the Stockholder to freely trade the shares of
common stock, par value $.10 per share, of the Company ("Common Stock")
received by the Stockholder pursuant to the Merger may be limited by applicable
federal securities laws so that such shares of Common Stock may be less liquid
than the shares of Common Stock received pursuant to the Merger by other
stockholders of COC;

         WHEREAS, in order to improve the transferability of the Common Stock
to be received by the Stockholder pursuant to the Merger, the Stockholder has
requested the Company to provide to the Stockholder limited registration rights
with respect to the shares of Common Stock to be received by the Stockholder
pursuant to the Merger and the Company has agreed to provide such rights on the
terms and subject to the conditions herein; and

         WHEREAS, the execution and delivery of this Agreement by the Company
and the Stockholder is a condition to the obligation of the Company to effect
the Merger;

         NOW, THEREFORE, in consideration of the premises and the mutual
agreements herein set forth and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto,
intending to be legally bound, hereby agree as follows:
<PAGE>   128
                                   ARTICLE I

                              REGISTRATION RIGHTS

         The Company and the Stockholder covenant and agree as follows:

         1.1     Definitions.  For purposes of this Agreement:

         (a)     The terms "register," "registered" and "registration" refer to
a registration of securities effected by preparing and filing a registration
statement or similar document in compliance with the Securities Act (as defined
below), and the declaration or ordering of effectiveness of such registration
statement or document.

         (b)     The term "Registrable Securities" means (i) the Common Stock
received by the Stockholder pursuant to the Merger and (ii) a dividend or other
distribution with respect to, or in exchange for or in replacement of, such
Common Stock.

         (c)     The term "Restricted Securities" means the Registrable
Securities upon original issuance thereof, subject to the provisions of Section
1.2 hereof.

         (d)     The term "Person" means an individual, partnership,
corporation, trust or unincorporated organization, or government or agency or
political subdivision thereof.

         (e)     The term "Board" means the Board of Directors of the Company.

         (f)     The term "Commission" means the Securities and Exchange
Commission.

         (g)     The term "Securities Act" means the Securities Act of 1933, as
amended, and the term "Exchange Act" means the Securities Exchange Act of 1934,
as amended.

         (h)     The term "GECC Agreement" means that certain Registration
Rights Agreement dated as of January 29, 1988, between the Company and General
Electric Capital Corporation, as amended by the First Amendment thereto dated
February 5, 1993.

         (i)     The term "Beall Agreement" means that certain Registration
Agreement dated as of April 22, 1994, between the Company and Joseph E. Beall.

         1.2     Securities Subject to this Agreement.  The securities entitled
to the benefits of this Agreement are the Registrable Securities but with
respect to any particular Registrable Security, only so long as such security
continues to be a Restricted Security.  A Registrable Security ceases to be a
Restricted Security when (a) it has been effectively registered under the
Securities Act and disposed of in accordance with the registration statement
covering it, (b) it is sold pursuant to Rule 144 or Rule 145 (or any similar
provision then in force) under the Securities Act or (c) it has otherwise been
transferred by the Stockholder.





                                      -2-
<PAGE>   129
         1.3     Demand Registration.

         (a)     If the Company shall receive, at any time after the later of
(i) the expiration of the term of the GECC Agreement and (ii) the time when
financial statements that include at least 30 days of combined operations of
the Company and COC after the Merger have been publicly reported, and prior to
the fifth anniversary of the date of this Agreement, a written request from the
Stockholder that the Company file a registration statement under the Securities
Act covering the registration of Registrable Securities, then the Company
shall, subject to the limitations of Sections 1.3(c), 1.5 and 1.7 hereof,
effect the registration of all Registrable Securities that the Stockholder
requests to be registered within 30 days of the receipt by the Company of such
written request by means of a "shelf" registration statement on any appropriate
form under the Securities Act for an offering to be made on a continuous basis
pursuant to Rule 415 under the Securities Act.  The Company agrees to use its
best efforts to keep such shelf registration statement continuously effective
for a period of six months following the date on which such shelf registration
statement is declared effective (plus the number of days of any discontinuance
described below).

         (b)     If the Stockholder intends to distribute the Registrable
Securities covered by the request by means of an underwriting, it shall so
advise the Company as a part of its request made pursuant to this Section 1.3.

         (c)     The Company is obligated to effect two registrations pursuant
to this Section 1.3; provided, however, that (i) the Company shall only be
required to effect one registration of Registrable Securities under this
Section 1.3 within any two-year period; (ii) if the Stockholder has the
opportunity under Section 1.4 to register Registrable Securities during the
term of this Agreement prior to the time the Company has effected two
registrations pursuant to this Section 1.3, then the Company shall only be
obligated to effect one registration under this Section 1.3 during the term of
this Agreement; (iii) the Stockholder shall lose the right to demand one
registration pursuant to this Section if the number of Registrable Securities
then held by the Stockholder decreases to less than five percent of the then
outstanding Common Stock; and (iv) the Company shall not be obligated to effect
any registration requested pursuant to this Section 1.3 if the number of shares
of Registrable Securities then held by the Stockholder shall be less than one
percent of the then outstanding Common Stock.  A registration shall not be
deemed to have been effected (i) unless it has become effective and remained
effective for the period specified in Section 1.3(a) or until the Registrable
Securities registered under such registration statement have been sold, or
(ii), if, after it has become effective, such registration is terminated by a
stop order, injunction or other order of the Commission or other governmental
agency or court.

         (d)     Subject to Section 1.3(e), any holder of shares of Common
Stock of the Company that is a party to an agreement with the Company pursuant
to which such holder is granted registration rights under the Securities Act
shall also have the right to include such shares in any shelf registration
pursuant to this Section 1.3.

         (e)     If any of the Registrable Securities registered pursuant to
any shelf registration pursuant to this Section 1.3 are to be sold in one or
more underwritten offerings, and the managing underwriter or underwriters
deliver an opinion to the Company and the Stockholder





                                      -3-
<PAGE>   130
that the total number of shares of Common Stock which the Stockholder and any
other Persons intend to include in such offering exceeds the number of shares
that can be sold in such offering, there shall be included in such underwritten
offering the number of shares of Common Stock which in the opinion of such
underwriters can be sold, and such shares shall be allocated pro rata among the
holders of shares of Common Stock to be sold on the basis of the number of
shares of Common Stock to be registered; provided, that if shares of Common
Stock are being offered for the account of other Persons as well as the
Stockholder, a reduction in number of shares shall first be made from the
shares intended to be offered by such Persons other than the Stockholder.

         (f)     Anything in this Agreement to the contrary notwithstanding,
the Company shall not be required to register any Registrable Securities
pursuant to this Section 1.3 if the Stockholder had the opportunity to register
Registrable Securities pursuant to Section 1.4 hereof within the six months
immediately preceding such request, but declined to do so; provided, however,
that the provisions of this paragraph (f) shall not apply if the Stockholder
requested registration of such Registrable Securities pursuant to Section 1.4
hereof and 25 percent or more of such Registrable Securities were excluded from
the offering by the managing underwriter or underwriters thereof.

         1.4     Company Registration.  At any time within five years of the
date of this Agreement that the Company proposes to register (including for
this purpose a registration effected by the Company for stockholders other than
the Stockholder, except as set forth below with respect to shares offered
pursuant to the Beall Agreement) any shares of its Common Stock under the
Securities Act for sale within such five-year period (other than registration
of the Company's Common Stock for issuance or sale (a) pursuant to Section 1.3
hereof, (b) pursuant to the Beall Agreement or (c) in connection with (i)
employee or non-employee director compensation or benefit programs, (ii) an
exchange offer or an offering of securities solely to the existing stockholders
or employees of the Company or (iii) an acquisition, merger or other business
combination using a registration statement on Form S-4 or any successor or
other appropriate form), the Company will give prompt written notice (which, in
any event, shall be given no less than 15 days prior to the filing of a
registration statement with respect to such offering) to the Stockholder of its
intention so to do and, upon the written request of the Stockholder sent within
15 days after the effective date of any such notice, the Company will, subject
to the provisions of Sections 1.5 and 1.7 hereof, use its best efforts to cause
all Registrable Securities as to which the Stockholder shall have so requested
registration, to be registered under the Securities Act, all to the extent
necessary to permit the sale in such offering of the Registrable Securities so
registered on behalf of the Stockholder in the same manner as the Company (or
stockholder other than the Stockholder, as the case may be) proposes to offer
its shares of Common Stock.  The Company shall use its best efforts to cause
the managing underwriter or underwriters of a proposed underwritten offering to
permit the Registrable Securities requested by the Stockholder to be included
in the registration for such offering on the same terms and conditions as the
shares of Common Stock of the Company included therein.  Notwithstanding the
foregoing, if the managing underwriter or underwriters of such offering deliver
an opinion to the Company and the Stockholder that the total number of shares
of Common Stock which the Stockholder or the Company, and any other Person,
intend to include in such offering will in the good faith opinion of such
managing underwriter or underwriters materially and adversely affect the
success of such offering, then the number of shares of





                                      -4-
<PAGE>   131
Common Stock to be offered for the account of the Stockholder shall be reduced
pro rata based upon the number of shares of Common Stock proposed to be sold by
the Company, the Stockholder and other Persons to the extent necessary to
reduce the total number of shares of Common Stock to be included in such
offering to the number of shares recommended by such managing underwriter;
provided, that if shares of Common Stock are being offered for the account of
other Persons as well as the Company, such reduction shall first be made from
the shares of Common Stock intended to be offered by such Persons other than
the Stockholder.

         1.5     Obligations of the Company.  If and whenever the Company is
required by the provisions of this Agreement to use its best efforts to effect
the registration of any Registrable Securities, the Company shall as
expeditiously as reasonably practicable:

         (a)     Prepare and file with the Commission a registration statement
on an appropriate form under the Securities Act and use its best efforts to
cause such registration statement to become effective; provided, that before
filing a registration statement or prospectus or any amendments or supplements
thereto, including documents incorporated by reference after the initial filing
of any registration statement, as soon as practicable, the Company will furnish
to the Stockholder and the underwriters, if any, copies of all such documents
proposed to be filed, which documents will be subject to the review of the
Stockholder and the underwriters, and the Company will not file any
registration statement or amendment thereto, or any prospectus or any
supplement thereto (including such documents incorporated by reference) to
which the Stockholder or the underwriters, if any, shall reasonably object in
the light of the requirements of the Securities Act and any other applicable
laws and regulations.

         (b)     Prepare and file with the Commission such amendments and
post-effective amendments to a registration statement as may be necessary to
keep such registration statement effective for the applicable period; cause the
related prospectus to be filed pursuant to Rule 424(b) under the Securities
Act; cause such prospectus to be supplemented by any required prospectus
supplement and, as so supplemented, to be filed pursuant to Rule 424(b) under
the Securities Act; and comply with the provisions of the Securities Act with
respect to the disposition of all securities covered by such registration
statement during the applicable period in accordance with the intended methods
of disposition set forth in such registration statement or supplement to such
prospectus.

         (c)     Notify the Stockholder and the managing underwriters, if any,
promptly, and (if requested by any such Person) confirm such advice in writing,
(i) when a prospectus or any prospectus supplement or post-effective amendment
has been filed, and, with respect to a registration statement or any
post-effective amendment, when the same has become effective, (ii) of any
request by the Commission for amendments or supplements to a registration
statement or related prospectus or for additional information, (iii) of the
issuance by the Commission of any stop order suspending the effectiveness of a
registration statement or the initiation of any proceedings for that purpose,
(iv) if at any time the representations and warranties of the Company
contemplated by Section 1.5(l) cease to be true and correct, (v) of the receipt
by the Company of any notification with respect to the suspension of the
qualification of any of the Registrable Securities for sale in any jurisdiction
or the initiation of any proceeding for such purpose, (vi) of the happening of
any event which requires the making of any changes in a registration statement
or related prospectus so that such documents will not contain any untrue





                                      -5-
<PAGE>   132
statement of a material fact or omit to state any material fact required to be
stated therein or necessary to make the statements therein not misleading and
(vii) of the Company's reasonable determination that a post-effective amendment
to a registration statement would be appropriate or that there exist
circumstances not yet disclosed to the public which make further sales under
such registration statement inadvisable pending such disclosures and
post-effective amendment.

         (d)     Make reasonable efforts to obtain the withdrawal of any order
suspending the effectiveness of a registration statement, or the lifting of any
suspension of the qualification of any of the Registrable Securities for sale
in any jurisdiction, at the earliest possible moment.

         (e)     If requested by the managing underwriters or the Stockholder
in connection with an underwritten offering, immediately incorporate in a
prospectus supplement or post-effective amendment such information as the
managing underwriters and the Stockholder agree should be included therein
relating to such sale and distribution of Registrable Securities, including,
without limitation, information with respect to the number of shares of
Registrable Securities being sold to such underwriters and the purchase price
being paid therefor by such underwriters and with respect to any other terms of
the underwritten (or best efforts underwritten) offering of the Registrable
Securities to be sold in such offering; make all required filings of such
prospectus supplement or post-effective amendment as soon as notified of the
matters to be incorporated in such prospectus supplement or post- effective
amendment; and supplement or make amendments to any registration statement if
requested by the Stockholder or any underwriter of such Registrable Securities.

         (f)     Furnish to the Stockholder and each managing underwriter, if
any, without charge, at least one signed copy of the registration statement,
any post-effective amendment thereto, including financial statements and
schedules, all documents incorporated therein by reference and all exhibits
(including those incorporated by reference).

         (g)     Deliver without charge to the Stockholder and the
underwriters, if any, as many copies of the prospectus or prospectuses
(including each preliminary prospectus) and any amendment or supplement thereto
as such Persons may reasonably request; and the Company consents to the use of
such prospectus or any amendment or supplement thereto by the Stockholder and
the underwriters, if any, in connection with the offer and sale of the
Registrable Securities covered by such prospectus or any amendment or
supplement thereto.

         (h)     Prior to any public offering of Registrable Securities,
register or qualify or cooperate with the Stockholder, the underwriters, if
any, and respective counsel in connection with the registration or
qualification of such Registrable Securities for offer and sale under the
securities or Blue Sky laws of such jurisdictions as the Stockholder or an
underwriter reasonably requests in writing; keep each such registration or
qualification effective during the period such registration statement is
required to be kept effective and do any and all other acts or things necessary
or advisable to enable the disposition in such jurisdictions of the Registrable
Securities covered by the applicable registration statement; provided, however,
that the Company will not be required in connection therewith or as a condition
thereto to qualify generally to do business or subject itself to general
service of process in any such jurisdiction where it is not then so subject.





                                      -6-
<PAGE>   133
         (i)     Cooperate with the Stockholder and the managing underwriters,
if any, to facilitate the timely preparation and delivery of certificates
representing Registrable Securities to be sold and not bearing any restrictive
legends; and enable such Registrable Securities to be in such denominations and
registered in such names as the managing underwriters may request at least two
business days prior to any sale of Registrable Securities to the underwriters.

         (j)     Use its best efforts to cause the Registrable Securities
covered by the applicable registration statement to be registered with or
approved by such other governmental agencies or authorities as may be
necessary, if any, to consummate the disposition of such Registrable
Securities.

         (k)     Upon the occurrence of any event contemplated by Section
1.5(c) (ii) - (vii) above, prepare a supplement or post- effective amendment to
the applicable registration statement or related prospectus or any document
incorporated therein by reference or file any other required document so that,
as thereafter delivered to the purchaser of the Registrable Securities being
sold thereunder, such prospectus will not contain an untrue statement of a
material fact or omit to state any material fact necessary to make the
statements therein not misleading.

         (l)     Enter into such agreements (including an underwriting
agreement) and take all such other actions in connection therewith in order to
expedite or facilitate the disposition of such Registrable Securities and in
such connection, whether or not an underwriting agreement is entered into and
whether or not the Registrable Securities to be covered by such registration
are to be offered in an underwritten offering:  (i) make such representations
and warranties to the Stockholder with respect to the registration statement,
prospectus and documents incorporated by reference, if any, in form, substance
and scope as are customarily made by issuers to underwriters in underwritten
offerings and confirm the same if and when requested; (ii) obtain opinions of
counsel to the Company and updates thereof with respect to the registration
statement and the prospectus in the form, scope and substance which are
customarily delivered in underwritten offerings; (iii) in the case of an
underwritten offering, enter into an underwriting agreement in form, scope and
substance as is customary in underwritten offerings and obtain opinions of
counsel to the Company and updates thereof (which counsel and opinions (in
form, scope and substance) shall be reasonably satisfactory to the managing
underwriters and the Stockholder) addressed to the Stockholder and the
underwriters, if any, covering the matters customarily covered in opinions
delivered in underwritten offerings and such other matters as may be reasonably
requested by the Stockholder and such underwriters; (iv) obtain "cold comfort"
letters and updates thereof from the Company's independent certified public
accountants addressed to the Stockholder and the underwriters, if any, such
letters to be in customary form and covering matters of the type customarily
covered in "cold comfort" letters by accountants in connection with
underwritten offerings; (v) if any underwriting agreement is entered into, the
same shall set forth in full the indemnification provisions and procedures
customarily included in underwriting agreements in underwritten offerings; and
(vi) the Company shall deliver such documents and certificates as may be
requested by the Stockholder and the managing underwriters, if any, to evidence
compliance with clause (i) above and with any customary conditions contained in
the underwriting agreement or other agreement entered into by the Company.  The
above shall be done at each closing under such underwriting or similar
agreement or as and to the extent required thereunder.





                                      -7-
<PAGE>   134
         (m)     Make available for inspection by a representative of the
Stockholder, any underwriter participating in any disposition pursuant to such
registration, and any attorney or accountant retained by the Stockholder or
such underwriter, all financial and other records, pertinent corporate
documents and properties of the Company, and cause the Company's officers,
directors and employees to supply all information reasonably requested by any
such representative, underwriter, attorney or accountant in connection with
such registration; provided that any records, information or documents that are
designated by the Company in writing as confidential shall be kept confidential
by such Persons unless disclosures of such records, information or documents is
required by court or administrative order.

         (n)     Otherwise use its best efforts to comply with all applicable
rules and regulations of the Commission and make generally available to its
security holders earning statements satisfying the provisions of Section 11(a)
of the Securities Act, no later than 90 days after the end of any 12-month
period (i) commencing at the end of any fiscal quarter in which Registrable
Securities are sold to underwriters in a firm or best efforts underwritten
offering and (ii) beginning with the first day of the Company's first fiscal
quarter next succeeding each sale of Registrable Securities after the effective
date of a registration statement, which statements shall cover said 12-month
periods.

         (o)     If the Company, in the exercise of its reasonable judgment,
objects to any change reasonably requested by the Stockholder or the
underwriters, if any, to any registration statement or prospectus or any
amendments or supplements thereto (including documents incorporated or to be
incorporated therein by reference) as provided for in this Section 1.5, the
Company shall not be obligated to make any such change and the Stockholder may
withdraw its Registrable Securities from such registration, in which event (i)
the Company shall pay all registration expenses (including its counsel fees and
expenses) incurred in connection with such registration statement or amendment
thereto or prospectus or supplement thereto, (ii) in the case of a shelf
registration, the shelf registration statement or amendment thereto shall be
filed as soon as agreement with respect to any proposed change shall be reached
among all the applicable parties and (iii) in the case of a registration being
effected pursuant to Section 1.3, such registration shall not count as one of
the registrations the Company is obligated to effect pursuant to Section 1.3(c)
hereof.

         In connection with any registration of Registrable Securities, the
Company may require the Stockholder to furnish to the Company such information
regarding itself and the distribution of such securities as the Company may
from time to time reasonably request in writing.

         The Stockholder agrees by acquisition of Registrable Securities that,
upon receipt of any notice from the Company of the happening of any event of
the kind described in Section 1.5(c)(ii)-(vii) hereof, the Stockholder will
forthwith discontinue disposition of Registrable Securities covered by such
registration statement or prospectus until the Stockholder's receipt of the
copies of the supplemented or amended prospectus contemplated by Section
1.5(c)(i) hereof, or until it is advised in writing by the Company that the use
of the applicable prospectus may be resumed, and has received copies of any
additional or supplemental filings which are incorporated by reference in such
prospectus, and, if so directed by the Company, the Stockholder will deliver to
the Company (at the Company's expense) all copies, other than permanent file
copies then in the Stockholder's possession, of the prospectus covering such





                                      -8-
<PAGE>   135
Registrable Securities current at the time of receipt of such notice.  In the
event the Company shall give any such notice, the time period mentioned in
Section 1.3(a) shall be extended by the number of days during the time period
from and including the date of the giving of such notice pursuant to Section
1.5(c) hereof to and including the date when the Stockholder shall have
received the copies of the supplemented or amended prospectus contemplated by
Section 1.5(c) hereof.

         1.6     Expenses of Registration.  All expenses incurred in connection
with a registration, filing or qualification pursuant to Section 1.3 hereof
(other than fees and expenses of the Company's counsel), including, without
limitation, registration, filing and qualification fees, printers' and
accounting fees, and the fees and disbursements of counsel for the Stockholder,
shall be borne and paid by the Stockholder, pro rata in such proportion as the
number of Registrable Securities registered pursuant to such registration bears
to the total amount of securities registered pursuant thereto.  All expenses
incurred in connection with a registration pursuant to Section 1.4 (including,
but not limited to the expenses enumerated in the preceding sentence) shall be
borne by the Company, with the exception of fees and disbursements of the
Stockholder's counsel, which shall be borne by the Stockholder.  In addition,
the Stockholder shall bear and pay all underwriting discounts and selling
commissions attributable to sales of Registrable Securities.

         1.7     Underwritten Registrations.

         (a)     If any of the Registrable Securities covered by any
registration under Section 1.3 are to be sold in an underwritten offering, the
investment banker or investment bankers and manager or managers that will
administer the offering will be selected by the Stockholder; provided, that
such investment bankers and managers must be reasonably satisfactory to the
Company.

         (b)     The Stockholder may not participate in any underwritten
registration under Section 1.4 hereunder unless it (i) agrees to sell its
securities on the basis provided in any underwriting arrangements approved and
(ii) completes and executes all questionnaires, powers of attorney,
indemnities, underwriting agreements and other documents required under the
terms of such underwriting arrangements.  In connection with any underwritten
offering including securities being issued or sold by the Company, the Company
shall be entitled to approve the terms of the underwriting arrangements.

         1.8     Indemnification.  In the event any Registrable Securities are
included in a registration statement under this Agreement:

         (a)     To the extent permitted by law, the Company will indemnify and
hold harmless the Stockholder, the officers and directors of the Stockholder,
each underwriter of Registrable Securities and each other Person, if any, who
controls the Stockholder or such underwriter within the meaning of Section 15
of the Securities Act, against any losses, claims, damages, liabilities or
expenses, joint or several, to which any such Person may become subject under
the Securities Act or otherwise, insofar as such losses, claims, damages,
liabilities or expenses (or actions in respect thereof) arise out of or are
based upon (i) any untrue statement or alleged untrue statement of a material
fact contained in any registration statement under which such





                                      -9-
<PAGE>   136
Registrable Securities were registered under the Securities Act pursuant
hereto, or any post-effective amendment thereof, or the omission or alleged
omission therefrom of a material fact required to be stated therein or
necessary to make the statements therein not misleading, or (ii) any untrue
statement or alleged untrue statement of a material fact contained in any
preliminary prospectus, if used prior to the effective date of the registration
statement and not corrected in the final prospectus, or contained in the final
prospectus (as amended or supplemented, if the Company shall have filed with
the Commission any amendment thereof or supplement thereto), or the omission or
alleged omission therefrom of a material fact required to be stated therein or
necessary to make the statements therein not misleading; and will reimburse any
such Person for any legal or other expenses reasonably incurred by such Person
in connection with investigating or defending any such loss, claim, damage,
liability or expense; provided, however, that the indemnity agreement contained
in this Section 1.8(a) shall not apply to amounts paid in settlement of any
such loss, claim, damage, liability or expense if such settlement is effected
without the consent of the Company (which consent shall not be unreasonably
withheld); and provided further that the Company shall not be liable in any
such case to the extent that any such loss, claim, damage, liability or expense
arises out of or is based upon any such untrue statement or omission or alleged
untrue statement or omission which has been made in said registration
statement, preliminary prospectus, prospectus or amendment or supplement or
omitted therefrom in reliance upon and in conformity with information furnished
in writing to the Company by the Stockholder or such underwriter specifically
for use in the preparation thereof.

         (b)     To the extent permitted by law, the Stockholder will indemnify
and hold harmless the Company, each of its directors, each of its officers who
has signed the registration statement, each Person, if any, who controls the
Company within the meaning of Section 15 of the Securities Act, each
underwriter and each Person who controls any underwriter within the meaning of
Section 15 of the Securities Act, against any losses, claims, damages,
liabilities or expenses, joint or several, to which the Company or any such
Person, may become subject under the Securities Act or otherwise, and will
reimburse the Company or any such Person for any legal or other expenses
reasonably incurred by the Company or such Person in connection with
investigating or defending any such loss, claim, damage, liability or expense,
but only insofar as such losses, claims, damages, liabilities or expenses (or
actions in respect thereof) arise out of or are based upon any untrue statement
or omission or alleged untrue statement or omission of a material fact referred
to in clause (i) or (ii) of Section 1.8(a) hereof, in each case to the extent
(and only to the extent) that such untrue statement or omission or alleged
untrue statement or omission was made in reliance upon and in conformity with
information furnished in writing by or on behalf of the Stockholder
specifically for use in connection with such registration; provided, however,
that the indemnity agreement contained in this Section 1.8(b) shall not apply
to amounts paid in settlement of any such loss, claim, damage, liability or
expense if such settlement is effected without the consent of the Stockholder,
which consent shall not be unreasonably withheld.

         (c)     Promptly after receipt by an indemnified party under this
Section 1.8 of notice of the commencement of any action (including any
governmental action), such indemnified party will, if a claim in respect
thereof is to be made against an indemnifying party under this Section 1.8,
notify the indemnifying party in writing of the commencement thereof and the
indemnifying party shall have the right to participate in, and, to the extent
the indemnifying party so desires,





                                      -10-
<PAGE>   137
to assume the defense thereof with counsel mutually satisfactory to the
parties; provided, however, that an indemnified party shall have the right to
retain its own counsel, with the fees and expenses to be paid by the
indemnifying party, if representation of such indemnified party by the counsel
retained by the indemnifying party would be inappropriate due to actual or
potential differing interests between such indemnified party and any other
party represented by such counsel in such proceeding.  The failure so to notify
an indemnifying party within a reasonable time of the commencement of any such
action, if prejudicial to its ability to defend such action, shall relieve such
indemnifying party of any liability to the indemnified party under this Section
1.8, but the omission so to notify the indemnifying party will not relieve it
of any liability that it may have to any indemnified party otherwise than under
this Section 1.8.

         (d)     If the indemnification provided for in this Section 1.8 from
the indemnifying party is unavailable to an indemnified party hereunder in
respect of any losses, claims, damages, liabilities or expenses referred to
herein, then the indemnifying party, in lieu of indemnifying such indemnified
party, shall contribute to the amount paid or payable by such indemnified party
as a result of such losses, claims, damages, liabilities or expenses in such
proportion as is appropriate to reflect the relative fault of the indemnifying
party and indemnified parties in connection with the actions which resulted in
such losses, claims, damages, liabilities or expenses, as well as any other
relevant equitable considerations.  The relative fault of such indemnifying
party and indemnified parties shall be determined by reference to, among other
things, whether any action in question, including any untrue or alleged untrue
statement of a material fact or omission or alleged omission to state a
material fact, has been made by, or relates to information supplied by, such
indemnifying party or indemnified parties, and the parties' relative intent,
knowledge, access to information and opportunity to correct or prevent such
action.  The amount paid or payable by a party as a result of the losses,
claims, damages, liabilities and expenses referred to above shall be deemed to
include, subject to the limitations set forth in Section 1.8(c) hereof, any
legal or other fees or expenses reasonably incurred by such party in connection
with any investigation or proceeding.

         The parties hereto agree that it would not be just and equitable if
contribution pursuant to this Section 1.8(d) were determined by pro rata
allocation or by any other method of allocation which does not take into
account the equitable considerations referred to in the immediately preceding
paragraph.  No Person guilty of fraudulent misrepresentation (within the
meaning of Section 11(f) of the Securities Act) shall be entitled to
contribution from any Person who was not guilty of such fraudulent
misrepresentation.

         1.9     Reports Under Exchange Act.  With a view to making available
to the Stockholder the benefits of Rule 145 under the Securities Act and any
other rule or regulation of the Commission that may at any time permit the
Stockholder to sell securities of the Company to the public without
registration, the Company agrees to:

         (a)     file with the Commission in a timely manner all reports and
other documents required of the Company under the Securities Act and the
Exchange Act, and the rules and regulations adopted by the Commission
thereunder; and

         (b)     furnish to the Stockholder forthwith upon request (i) a
written statement by the Company as to whether it has complied with the
reporting requirements of Rule 144, (ii) a copy





                                      -11-
<PAGE>   138
of the most recent annual or quarterly report of the Company and such other
reports and documents filed by the Company pursuant to the Exchange Act and
(iii) such other information as may be reasonably requested in availing the
Stockholder of any rule or regulation of the Commission which permits the sale
of any securities without registration.

         1.10    Assignment of Registration Rights.  The right to cause the
Company to register Registrable Securities pursuant to this Agreement may not
be assigned, in whole or in part, by the Stockholder without the prior written
consent of the Company.

         1.11    Limitations on Subsequent Registration Rights.  From and after
the date of this Agreement, the Company shall not, without the prior written
consent of the Stockholder, enter into any agreement with any holder or
prospective holder of any securities of the Company which grants registration
rights under the Securities Act on terms and conditions more favorable than the
rights granted to the Stockholder in this Agreement.  The Company is not a
party to any currently subsisting agreement with respect to its securities
granting any registration rights to any Person, except the GECC Agreement and
the Beall Agreement.

         1.12    Hold-Back Agreements.

         (a)     If a registration statement is filed pursuant to Section 1.3
or 1.4 hereof, the Stockholder agrees not to effect any public sale or
distribution of the issue being registered or similar security of the Company,
including a sale pursuant to Rule 144 or Rule 145 under the Securities Act
(except as part of such underwritten registration), during the 14-day period
prior to, and during the 90-day period beginning on, the closing date of each
underwritten offering made pursuant to such registration statement, to the
extent timely notified in writing by the Company or the managing underwriters.

         (b)     The Company agrees (i) not to effect any public sale or
distribution of any securities similar to those being registered during the
14-day period prior to, and during the 90-day period beginning on, the
effective date of a registration statement filed pursuant to Section 1.3 or 1.4
hereof (except as part of such underwritten registration or in connection with
(A) employee or non-employee director compensation or benefit programs, (B) an
exchange offer or an offering of securities solely to the existing stockholders
or employees of the Company, or (C) an acquisition, merger or other business
combination using a registration statement on Form S-4 or any successor or
other appropriate form), and (ii) to cause each holder of its privately placed
securities purchased from the Company at any time on and after the date of this
Agreement to agree not to effect any public sale or distribution of any such
securities during such period, including a sale pursuant to Rule 144 under the
Securities Act (except as part of such underwritten registration, if
permitted).


                                   ARTICLE II

                                 MISCELLANEOUS

         2.1     Successors and Assigns; No Third Party Benefit.  This
Agreement shall be binding upon and inure to the benefit of the parties and
their respective permitted successors and assigns.





                                      -12-
<PAGE>   139
Nothing in this Agreement, express or implied, is intended to confer upon any
party other than the parties hereto and their respective permitted successors
and assigns any rights or remedies under or by reason of this Agreement, except
as expressly provided in this Agreement.

         2.2     Governing Law.  This Agreement shall be governed by, and
construed and enforced in accordance with, the substantive laws of the State of
Texas, without giving effect to the principles of conflicts of law thereof.

         2.3     Counterparts.  This Agreement may be executed by the parties
hereto in separate counterparts, each of which when so executed and delivered
shall be deemed an original, but all such counterparts shall together
constitute one and the same instrument.  Each counterpart may consist of a
number of copies hereof each signed by less than all, but together signed by
all, the parties hereto.

         2.4     Titles and Subtitles.  The titles and subtitles used in this
Agreement are inserted for convenience only and are not to be considered in
construing or interpreting this Agreement.

         2.5     Notices.  All notices and other communications provided for or
permitted hereunder shall be made in writing and shall be delivered by (a)
personal delivery, (b) expedited delivery service or (c) certified or
registered mail, postage prepaid.  Any such notice shall be deemed given upon
its receipt at the following address:

         (i)     If to the Stockholder, initially at Potomac Tower, Suite 1700,
1001 19th Street North, Arlington, Virginia 22209 and thereafter at such other
address, notice of which is given to the Company in accordance with this
Section 2.5; and

         (ii)    If to the Company, initially at 10370 Richmond Avenue, Suite
400, Houston, Texas 77042 and thereafter at such other address, notice of which
is given in accordance with this Section 2.5.

         2.6     Adjustments Affecting Registrable Securities.  The Company
will not take any action, or permit any change to occur, with respect to the
Registrable Securities which would adversely affect (a) the ability of the
Stockholders to include such Registrable Securities in a registration
undertaken pursuant to this Agreement or (b) the marketability of such
Registrable Securities in any such registration.

         2.7     Amendments and Waivers.  The provisions of this Agreement,
including the provisions of this sentence, may not be amended, modified or
supplemented, and waivers or consents to departures from the provisions hereof
(which may be generally or in a particular instance and either retroactively or
prospectively) may not be given, unless the Company has obtained the written
consent of the Stockholder.

         2.8     Severability.  If any provision or any portion of any
provision of this Agreement or the application of such provision or any portion
thereof to any Person or circumstance shall be held invalid or unenforceable,
the remaining portion of such provision, as it applies to other Persons or
circumstances and the remaining provisions, shall not be affected or impaired
thereby.





                                      -13-
<PAGE>   140
         2.9     Entire Agreement.  This Agreement is intended by the parties
as a final expression of their agreement and intended to be a complete and
exclusive statement of the agreement and understanding of the parties hereto in
respect of the subject matter herein contained.  There are no restrictions,
promises, warranties or undertakings, other than those set forth or referred to
herein, with respect to the registration rights granted by the Company with
respect to the securities received by the Stockholder pursuant to the Merger.
This Agreement supersedes all prior agreements and understandings between the
parties with respect to such subject matter.





                                      -14-
<PAGE>   141
         IN WITNESS WHEREOF, the parties have caused this Agreement to be duly
executed as of the date first above written.

                                        NOBLE DRILLING CORPORATION



                                        By:__________________________________
                                           James C. Day, Chairman, President and
                                            Chief Executive Officer


                                        P.A.J.W. CORPORATION



                                        By:__________________________________
                                           Name:
                                           Title:





                                      -15-
<PAGE>   142
 
                           GLOSSARY OF DEFINED TERMS
 
<TABLE>
<CAPTION>
                                                                                        PAGE
                                                                                        ----
<S>                                                                                     <C>
Agreement.............................................................................    1
Noble.................................................................................    1
Sub...................................................................................    1
Chiles................................................................................    1
Merger................................................................................    1
Chiles Common Stock...................................................................    1
Noble Common Stock....................................................................    1
Chiles Preferred Stock................................................................    1
$1.50 Noble Preferred Stock...........................................................    1
Code..................................................................................    1
DGCL..................................................................................    1
Surviving Corporation.................................................................    1
Closing...............................................................................    1
Closing Date..........................................................................    1
Effective Time........................................................................    1
Shares................................................................................    2
Noble Subsidiaries....................................................................    4
Noble Disclosure Letter...............................................................    4
Noble Certificate.....................................................................    4
Noble Charter Amendment...............................................................    4
$2.25 Noble Preferred Stock...........................................................    4
Triton Agreement......................................................................    4
Noble Options.........................................................................    5
HSR Act...............................................................................    5
Commission............................................................................    6
Securities Act........................................................................    6
Exchange Act..........................................................................    6
Noble Commission Filings..............................................................    6
Permitted Liens.......................................................................    7
Noble ERISA Affiliate.................................................................    7
ERISA.................................................................................    7
Plan..................................................................................    7
Benefit Program or Agreement..........................................................    7
Tax Returns...........................................................................    8
Taxes.................................................................................    8
Tax...................................................................................    8
Environmental Laws....................................................................   10
CERCLA................................................................................   10
RCRA..................................................................................   10
OPA...................................................................................   10
Governmental Authority................................................................   10
Chiles Subsidiaries...................................................................   11
Chiles Disclosure Letter..............................................................   11
Chiles Certificate....................................................................   11
Chiles Options........................................................................   11
Chiles 1990 Plan......................................................................   11
Chiles Commission Filings.............................................................   12
Chiles ERISA Affiliate................................................................   13
Proxy Statement.......................................................................   18
Chiles Acquisition Transaction........................................................   18
Registration Statement................................................................   20
Indemnified Parties...................................................................   22
Indemnified Liabilities...............................................................   22
Assumed Option........................................................................   24
HSN...................................................................................   26
Confidentiality Agreements............................................................   29
</TABLE>
<PAGE>   143
 
                                                                     APPENDIX II
 
                        SIMMONS & COMPANY INTERNATIONAL
                        700 Louisiana Street, Suite 5000
                              Houston, Texas 77002
                                  713-236-9999
 
June 13, 1994
 
Board of Directors
Noble Drilling Corporation
10370 Richmond Avenue, Suite 400
Houston, Texas 77042
 
Members of the Board:
 
You have requested the opinion of Simmons & Company International ("Simmons") as
investment bankers as to the fairness, from a financial point of view, to the
holders of common stock and $2.25 convertible exchangeable preferred stock
("$2.25 Noble Preferred Stock") of Noble Drilling Corporation ("Noble" or the
"Company") of the consideration to be paid by Noble in the proposed merger of
Chiles Offshore Corporation ("Chiles") with and into Noble Offshore Corporation,
a wholly owned subsidiary of the Company (the "Noble Sub"), pursuant to the
Agreement and Plan of Merger (the "Agreement"), to be executed by Noble, the
Noble Sub and Chiles (the "Proposed Merger").
 
As more specifically set forth in the Agreement, in the Proposed Merger each
issued and outstanding share of common stock of Chiles ("Chiles Common Stock")
will be converted into the right to receive 0.75 of a share of common stock, par
value of $.10 per share, of Noble ("Noble Common Stock"). Each issued and
outstanding share of $1.50 convertible preferred stock of Chiles ("Chiles
Preferred Stock") will be converted into the right to receive one share of a new
series of $1.50 convertible preferred stock of Noble having substantially the
same rights, privileges, preferences, and voting power as the Chiles Preferred
Stock.
 
Simmons, as a specialized energy-related investment banking firm, is engaged in,
among other things, the valuation of businesses and their securities in
connection with mergers and acquisitions, the management and underwriting of
sales of equity and debt to the public, and private placements of equity and
debt. Simmons has previously rendered investment banking services to the Company
in connection with a number of transactions for which Simmons received customary
compensation. In addition, in the ordinary course of business, Simmons may
actively trade the securities of Noble and Chiles for its own account and for
the accounts of customers and, accordingly, may at any time hold a long or short
position in such securities.
 
In connection with rendering its opinion, Simmons has reviewed and analyzed,
among other things, the following: (i) the Agreement; (ii) the financial
statements and other information concerning the Company, including the Annual
Reports on Form 10-K of the Company for each of the years in the three year
period ended December 31, 1993, the common stock and senior notes prospectuses
of the Company dated September 30, 1993, the Current Report on Form 8-K of the
Company dated April 22, 1994, and the Quarterly Report on Form 10-Q of the
Company for the quarter ended March 31, 1994; (iii) certain near-term forecasts
and other internal information, primarily financial in nature, concerning the
business and operations of the Company, and reflecting its recent acquisitions,
furnished by the Company for purposes of Simmons' analysis; (iv) certain
publicly available information concerning the trading of, and the trading market
for, Noble Common Stock and the $2.25 Noble Preferred Stock; (v) certain
publicly available information concerning Chiles, including the Annual Reports
on Form 10-K of Chiles for each of the years in the three year period ended
December 31, 1993, the preferred stock prospectus of Chiles dated October 14,
1993, and the Quarterly Report on Form 10-Q of Chiles for the quarter ended
March 31, 1994; (vi) certain near-term forecasts and other internal information,
primarily financial in nature, concerning the business and operations of Chiles
furnished by Chiles for purposes of Simmons' analysis; (vii) certain publicly
available information concerning the trading of, and the trading market for,
Chiles Common Stock and Chiles Preferred Stock; (viii) certain publicly
available information with respect to certain other companies that Simmons
believes to be comparable to the Company or Chiles ("Comparable Companies") and
the trading markets for
<PAGE>   144
 
Board of Directors
Noble Drilling Corporation
June 13, 1994
Page 2
 
such Comparable Companies' securities; (ix) certain publicly available
information concerning estimates of the future operating and financial
performance of the Company, Chiles and Comparable Companies prepared by industry
experts unaffiliated with either the Company or Chiles; and (x) certain publicly
available information concerning the nature and terms of certain other
transactions considered relevant to the inquiry. Simmons has also met with
certain officers and employees of the Company and Chiles to discuss the
foregoing as well as other matters believed relevant to the inquiry.
 
In the review and analysis and in arriving at its opinion, Simmons has assumed
and relied upon the accuracy and completeness of all of the financial and other
information provided by the Company and Chiles, or publicly available, including
without limitation, information with respect to asset conditions, tax positions,
liability reserves and insurance coverages, and has not attempted independently
to verify any of such information. Simmons has not conducted a physical
inspection of any of the assets, properties or facilities of the Company or
Chiles, nor has Simmons made or obtained any independent valuations or
appraisals of any of such properties or facilities, other than certain publicly
available estimates (the "Analyst Reports"). We have also assumed, with your
permission, that the Proposed Merger be treated as a "pooling of interests" in
accordance with generally accepted accounting principles.
 
In conducting its analysis and arriving at its opinion as expressed herein,
Simmons has considered such financial and other factors as it deemed appropriate
under the circumstances including, among others, the following: (i) the
historical and current financial position and results of operations of the
Company and Chiles; (ii) the business prospects of the Company and Chiles; (iii)
the financial performance and historical and current market for the equity
securities of Noble, Chiles and Comparable Companies; (iv) the relative value of
each company's assets, based upon the Analyst Reports and information contained
in each company's balance sheet; (v) the respective contributions in terms of
assets, and current and prospective earnings and cash flow of Noble and Chiles
to the combined company, and the relative ownership of Noble after the Proposed
Merger by the current holders of Noble Common Stock and Chiles Common Stock;
(vi) the pro forma effect of the Proposed Merger on Noble's capitalization
ratios, earnings per share and cash flow per share; and (vii) the nature and
terms of certain other acquisition transactions that Simmons believes to be
relevant. Simmons' analyses reflect recent acquisitions and current
capitalization structures of the Company and Chiles. Simmons has also taken into
account other financial analyses and studies deemed appropriate, its assessment
of general economic, market and financial conditions, and its experience in
connection with similar transactions and securities valuation generally.
Simmons' opinion necessarily is based upon conditions as they exist and can be
evaluated on, and on the information made available at, the date hereof.
 
Simmons is acting as financial advisor to the Company in this transaction and
will receive a customary fee for its services.
 
Based upon and subject to the foregoing, Simmons is of the opinion, as
investment bankers, that the consideration to be paid by the Company in the
Proposed Merger is fair, from a financial point of view, to holders of Noble
Common Stock and the $2.25 Noble Preferred Stock.
 
Sincerely,
 
SIMMONS & COMPANY INTERNATIONAL
 
/s/ NICHOLAS L. SWYKA
- ---------------------------
    Nicholas L. Swyka
    Managing Director
 
NLS/sm
<PAGE>   145
 
                                                                    APPENDIX III
 
SALOMON BROTHERS INC
Seven World Trade Center
New York, New York 10048
 
212-783-7000
 
                                                             SALOMON BROTHERS
 
June 13, 1994
 
The Board of Directors
Chiles Offshore Corporation
1400 Broadfield Boulevard, Suite 400
Houston, Texas 77084
 
Members of the Board:
 
You have requested our opinion as investment bankers as to the fairness, from a
financial point of view, to the holders of shares of common stock, par value
$0.01 per share (the "Company Common Stock"), and to holders of shares of $1.50
Convertible Preferred Stock, par value $1.00 per share (the "Company Preferred
Stock"), of Chiles Offshore Corporation (the "Company") of the consideration to
be received by such stockholders in the proposed merger of the Company with
Noble Offshore Corporation ("Acquiror Sub"), a wholly-owned subsidiary of Noble
Drilling Corporation ("Acquiror"), pursuant to the Agreement and Plan of Merger,
dated as of June 13, 1994 (the "Agreement"), among Acquiror, Acquiror Sub and
the Company (the "Proposed Merger").
 
As more specifically set forth in the Agreement, and subject to the terms and
conditions thereof, in the Proposed Merger, each issued and outstanding share of
the Company Common Stock will be converted into the right to receive 0.75 of a
share of common stock, par value $0.10 per share, of Acquiror (the "Acquiror
Common Stock") and each issued and outstanding share of Company Preferred Stock
will be converted into the right to receive one share of a new series of $1.50
convertible preferred stock of Acquiror (the "Acquiror Preferred Stock").
Pursuant to the Agreement, cash will be exchanged in lieu of fractional shares
of the Acquiror Common Stock.
 
As you are aware, Salomon Brothers Inc has acted as financial advisor to the
Company in connection with the Merger and will receive a fee for our services.
Salomon Brothers Inc has previously rendered certain investment banking and
financial advisory services to the Company for which we have received customary
compensation. Salomon Brothers Inc has also previously rendered investment
banking and financial advisory services to Acquiror for which we have received
customary compensation. In addition, in the ordinary course of our business, we
may actively trade the securities of the Company and Acquiror for our own
account and for the accounts of customers and, accordingly, may at any time hold
a long or short position in such securities.
 
In connection with rendering our opinion we have reviewed and analyzed, among
other things, the following: (i) the Agreement; (ii) certain publicly available
information concerning the Company, including the Annual Reports on Form 10-K of
the Company for each of the three years in the three year period ended December
31, 1993 and the Quarterly Report on Form 10-Q of the Company for the quarter
ended March 31, 1994; (iii) certain internal information, primarily historical
financial in nature, concerning the business and operations of the Company
furnished to us by the Company for purposes of our analysis; (iv) certain
publicly available information concerning the trading of, and the trading market
for, the Company Common Stock; (v) certain publicly available information
concerning Acquiror, including the Annual Reports on Form 10-K
<PAGE>   146
 
The Board of Directors
Chiles Offshore Corporation
June 13, 1994
Page 2
 
                                                             SALOMON BROTHERS
 
of Acquiror for each of the three years in the three year period ended December
31, 1993 and the Quarterly Report on Form 10-Q of the Acquiror for the quarter
ended March 31, 1994; (vi) certain internal information, primarily historical
financial in nature, concerning the business and operations of Acquiror
furnished to us by Acquiror for purposes of our analysis; (vii) certain publicly
available information concerning the trading of, and the trading market for, the
Acquiror Common Stock; (viii) certain publicly available information with
respect to certain other companies that we believe to be comparable to the
Company or Acquiror and the trading markets for certain of such other companies'
securities; and (ix) certain publicly available information concerning the
nature and terms of certain other transactions that we consider relevant to our
inquiry. We have also met with certain officers and employees of the Company and
Acquiror to discuss the foregoing as well as other matters we believe relevant
to our inquiry.
 
In our review and analysis and in arriving at our opinion, we have assumed and
relied upon the accuracy and completeness of all of the financial and other
information provided to us or publicly available and have not attempted
independently to verify any of such information. We have not conducted a
physical inspection of any of the properties or facilities of the Company of
Acquiror, nor have we made or obtained any independent appraisals of any of such
properties or facilities. We have assumed that the Acquiror Preferred Stock will
have substantially identical rights, privileges, preferences and voting power as
those of the Company Preferred Stock. In addition, we have assumed that the
Proposed Merger will not be taxable for the holders of the Company Common Stock
and the Company Preferred Stock, and that the Proposed Merger will be accounted
for as a pooling of interests.
 
In conducting our analysis and arriving at our opinion as expressed herein, we
have considered such financial and other factors as we have deemed appropriate
under the circumstances including, among others, the following: (i) the
historical and current financial position and results of operations of the
Company and Acquiror; (ii) the business prospects of the Company and Acquiror;
(iii) the historical and current trading market for the Company Common Stock,
for the Acquiror Common Stock and for the equity securities of certain other
companies that we believe to be comparable to the Company and Acquiror; and (iv)
the nature and terms of certain other acquisition transactions that we believe
to be relevant. We have also taken into account our assessment of general
economic, market and financial conditions and our experience in connection with
similar transactions and securities valuation generally. Our opinion is
necessarily based upon conditions as they exist and can be evaluated on the date
hereof. Our opinion as expressed herein is, in any event, limited to the
fairness, from a financial point of view, to the holders of the Company Common
Stock and the Company Preferred Stock, of the consideration to be received by
such holders in the Proposed Merger and does not address the Company's
underlying business decision to effect the Proposed Merger.
 
Based upon and subject to the foregoing, we are of the opinion as investment
bankers that the consideration to be received by the holders of the Company
Common Stock and the Company Preferred Stock in the Proposed Merger is fair,
from a financial point of view, to such holders.
 
Very truly yours,
 
SALOMON BROTHERS INC
/s/  Salomon Brothers Inc
<PAGE>   147
 
                                    PART II
 
                     INFORMATION NOT REQUIRED IN PROSPECTUS
 
ITEM 20. INDEMNIFICATION OF DIRECTORS AND OFFICERS.
 
     Noble is a Delaware corporation. Under Section 145 of the Delaware General
Corporation Law (the "DGCL"), Noble has the power to indemnify its directors and
officers, subject to certain limitations.
 
     Reference is made to Article VI of the Bylaws of Noble, which provides for
indemnification of directors and officers of Noble under certain circumstances.
 
     Pursuant to the DGCL, the Restated Certificate of Incorporation of Noble
limits the personal liability of the directors of Noble to Noble or its
stockholders for monetary damages for breach of fiduciary duty under certain
circumstances.
 
     Noble also maintains insurance to protect itself and its directors,
officers, employees and agents against expenses, liabilities and losses incurred
by such persons in connection with their service in the foregoing capacities.
 
     The foregoing summaries are necessarily subject to the complete text of the
statute, bylaws, restated certificate of incorporation and insurance policy
referred to above and are qualified in their entirety by reference thereto.
 
ITEM 21. EXHIBITS AND FINANCIAL STATEMENT SCHEDULES.
 
     The following exhibits are filed as part of this Registration Statement:
 
<TABLE>
<CAPTION>
       NUMBER                                          EXHIBIT
       ------                                          -------
           <S>          <C>
           2.1*         -- Agreement and Plan of Merger dated as of June 13, 1994, among Noble
                           Drilling Corporation, Noble Offshore Corporation and Chiles
                           Offshore Corporation (included as Appendix I to the Joint Proxy
                           Statement/Prospectus forming a part of this Registration
                           Statement).
           2.2          -- Stock Purchase Agreement dated April 22, 1994, between Joseph E.
                           Beall, George H. Bruce, Triton Engineering Services Company and
                           Noble Drilling Corporation (filed as Exhibit 2.1 to Noble Drilling
                           Corporation's Form 8-K dated May 6, 1994 and incorporated herein by
                           reference).
           2.3          -- Assets Purchase Agreement dated as of August 20, 1993 (the "Western
                           Assets Purchase Agreement"), between Noble Drilling Corporation and
                           The Western Company of North America (filed as Exhibit 2.1 to Noble
                           Drilling Corporation's Registration Statement on Form S-3 (No.
                           33-67130) and incorporated herein by reference).
           2.4          -- Agreement dated as of October 7, 1993, among Noble Drilling
                           Corporation, Noble Drilling (U.S.) Inc., Noble International
                           Limited, The Western Company of North America and Offshore
                           International Ltd., amending the Western Assets Purchase Agreement
                           (filed as Exhibit 2.2 to Noble Drilling Corporation's Form 8-K
                           dated October 15, 1993 and incorporated herein by reference).
           2.5          -- Exchange Agreement dated as of June 4, 1993 (the "Exchange
                           Agreement"), by and among Noble Drilling Corporation, Grasso
                           Corporation, Offshore Logistics, Inc., PPI-Seahawk Services, Inc.
                           and Noble Production Services Inc. (filed as Exhibit 2.2 to Noble
                           Drilling Corporation's Registration Statement on Form S-3 (No.
                           33-67130) and incorporated herein by reference).
</TABLE>
 
                                      II-1
<PAGE>   148
 
<TABLE>
<CAPTION>
       NUMBER                                          EXHIBIT
       ------                                          -------
<S>                     <C>
           2.6          -- Amendment No. 1 dated October 29, 1993 to the Exchange Agreement by
                           and among Noble Drilling Corporation, Grasso Corporation, Offshore
                           Logistics, Inc., PPI-Seahawk Services, Inc. and Noble Production
                           Services Inc. (filed as Exhibit 2.4 to Noble Drilling Corporation's
                           Annual Report on Form 10-K for the year ended December 31, 1993 and
                           incorporated herein by reference).
           2.7          -- Assignment and Assumption Agreement made as of October 28, 1993, by
                           and between Noble Production Management Inc., Noble Production
                           Services Inc., OLOG Production Management Inc., PPI-Seahawk
                           Services, Inc. and Grasso Corporation (filed as Exhibit 2.7 to
                           Noble Drilling Corporation's Annual Report on Form 10-K for the
                           year ended December 31, 1993 and incorporated herein by reference).
           2.8          -- Assets Purchase Agreement dated as of August 20, 1993 (the "Portal
                           Assets Purchase Agreement"), between Noble Drilling Corporation and
                           Portal Rig Corporation (filed as Exhibit 2.3 to Noble Drilling
                           Corporation's Registration Statement on Form S-3 (No. 33-67130) and
                           incorporated herein by reference).
           2.9          -- Agreement dated as of October 25, 1993, among Noble Drilling
                           Corporation, Noble (Gulf of Mexico) Inc. and Portal Rig
                           Corporation, amending the Portal Assets Purchase Agreement (filed
                           as Exhibit 2.5 to Noble Drilling Corporation's Quarterly Report on
                           Form 10-Q for the three-month period ended September 30, 1993 and
                           incorporated herein by reference).
           4.1          -- Restated Certificate of Incorporation of Noble Drilling Corporation
                           dated August 29, 1985 (filed as Exhibit 3.7 to Noble Drilling
                           Corporation's Registration Statement on Form 10 (No. 0-13857) and
                           incorporated herein by reference).
           4.2          -- Certificate of Amendment of Restated Certificate of Incorporation
                           of Noble Drilling Corporation dated May 5, 1987 (filed as Exhibit
                           4.2 to Noble Drilling Corporation's Registration Statement on Form
                           S-3 (No. 33-67130) and incorporated herein by reference).
           4.3          -- Certificate of Amendment of Restated Certificate of Incorporation
                           of Noble Drilling Corporation dated June 1, 1987 (filed as Exhibit
                           4.3 to Noble Drilling Corporation's Registration Statement on Form
                           S-3 and incorporated herein by reference).
           4.4          -- Certificate of Amendment of Restated Certificate of Incorporation
                           of Noble Drilling Corporation dated April 28, 1988 (filed as
                           Exhibit 3.12 to Noble Drilling Corporation's Annual Report on Form
                           10-K for the year ended December 31, 1988 and incorporated herein
                           by reference).
           4.5          -- Certificate of Amendment of Restated Certificate of Incorporation
                           of Noble Drilling Corporation dated April 27, 1989 (filed as
                           Exhibit 3.13 to Noble Drilling Corporation's Annual Report on Form
                           10-K for the year ended December 31, 1989, as amended, and
                           incorporated herein by reference).
           4.6          -- Certificate of Amendment of Restated Certificate of Incorporation
                           of Noble Drilling Corporation dated August 1, 1991 (filed as
                           Exhibit 3.16 to Noble Drilling Corporation's Annual Report on Form
                           10-K for the year ended December 31, 1991 and incorporated herein
                           by reference).
           4.7          -- Certificate of Designations of $2.25 Convertible Exchangeable
                           Preferred Stock, par value $1.00 per share, of Noble Drilling
                           Corporation, dated as of November 18, 1991 (filed as Exhibit 3.17
                           to Noble Drilling Corporation's Annual Report on Form 10-K for the
                           year ended December 31, 1991 and incorporated herein by reference).
</TABLE>
 
                                      II-2
<PAGE>   149
 
<TABLE>
<CAPTION>
       NUMBER                                          EXHIBIT
       ------                                          -------
<S>                     <C>
           4.8**        -- Form of Certificate of Designations of $1.50 Convertible Preferred
                           Stock, par value $1.00 per share, of Noble Drilling Corporation.
           4.9*         -- Form of certificate to evidence shares of $1.50 Convertible
                           Preferred Stock of Noble Drilling Corporation.
           4.10         -- Composite copy of the Bylaws of Noble Drilling Corporation as
                           currently in effect (filed as Exhibit 4.8 to Noble Drilling
                           Corporation's Registration Statement on Form S-3 (No. 33-67130) and
                           incorporated herein by reference).
           4.11         -- Indenture governing the 9 1/4% Senior Notes Due 2003 of Noble
                           Drilling Corporation (filed as Exhibit 4.1 to Noble Drilling
                           Corporation's Quarterly Report on Form 10-Q for the three-month
                           period ended September 30, 1993 and incorporated herein by
                           reference).
           4.12         -- Form of Senior Notes (included in Section 2.02 of the Indenture
                           filed as Exhibit 4.1 to Noble Drilling Corporation's Quarterly
                           Report on Form 10-Q for the three-month period ended September 30,
                           1993 and incorporated herein by reference).
           5.1**        -- Opinion of Thompson & Knight, A Professional Corporation.
           8.1**        -- Opinion of Thompson & Knight, A Professional Corporation.
          10.1*         -- Credit Agreement dated as of June 16, 1994 among Noble Drilling
                           Corporation, First Interstate Bank of Texas, N.A., in its
                           individual capacity and as agent, and Credit Lyonnais Cayman Island
                           Branch.
          10.2*         -- Revolving Credit Note dated June 16, 1994 of Noble Drilling
                           Corporation in the amount of $12,500,000 in favor of Credit
                           Lyonnais Cayman Island Branch.
          10.3*         -- Revolving Credit Note dated June 16, 1994 of Noble Drilling
                           Corporation in the amount of $12,500,000 in favor of First
                           Interstate Bank of Texas, N.A.
          10.4*         -- Guaranty Agreement dated as of June 16, 1994 by and among Noble
                           Drilling (U.S.) Inc., Noble Drilling (West Africa) Inc. and Noble
                           Drilling (Mexico) Inc.
          12.1*         -- Statement regarding computation of ratios.
          23.1*         -- Consent of Arthur Andersen & Co.
          23.2*         -- Consent of Arthur Andersen & Co.
          23.3*         -- Consent of KPMG Peat Marwick.
          23.4**        -- Consent of Thompson & Knight, A Professional Corporation (contained
                           in its opinion to be filed as Exhibit 5.1).
          23.5**        -- Consent of Thompson & Knight, A Professional Corporation (contained
                           in its opinion to be filed as Exhibit 8.1).
          23.6*         -- Consent of Simmons & Company International.
          23.7*         -- Consent of Salomon Brothers Inc .
          24.1*         -- Power of attorney (included on the signature page of this
                           Registration Statement).
</TABLE>
 
                                      II-3
<PAGE>   150
 
<TABLE>
<CAPTION>
       NUMBER                                          EXHIBIT
       ------                                          -------
          <S>           <C>
          99.1*         -- Form of Proxy of Noble Drilling Corporation (relating to the
                           Special Meeting of the stockholders of Noble Drilling Corporation
                           described in the Joint Proxy Statement/Prospectus forming a part of
                           this Registration Statement).
          99.2*         -- Form of Proxy of Chiles Offshore Corporation (relating to the
                           Special Meeting of the stockholders of Chiles Offshore Corporation
                           described in the Joint Proxy Statement/Prospectus forming a part of
                           this Registration Statement).
</TABLE>
 
- ---------------
 
 * Filed herewith.
** To be filed by amendment.
 
ITEM 22. UNDERTAKINGS.
 
     (b) Filings incorporating subsequent Exchange Act documents by reference.
 
     The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act of 1933, each filing of the
Registrant's Annual Report pursuant to Section 13(a) or Section 15(d) of the
Securities Exchange Act of 1934 that is incorporated by reference in the
Registration Statement shall be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.
 
     (h) Acceleration of effectiveness.
 
     Insofar as indemnification for liabilities arising under the Securities Act
of 1933 may be permitted to directors, officers and controlling persons of the
Registrant pursuant to the foregoing provisions, or otherwise, the Registrant
has been advised that in the opinion of the Securities and Exchange Commission
such indemnification is against public policy as expressed in the Act and is,
therefore, unenforceable. In the event that a claim for indemnification against
such liabilities (other than the payment by the Registrant of expenses incurred
or paid by a director, officer or controlling person of the Registrant in the
successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Act and will be governed by the final adjudication of
such issue.
 
  Requests for information incorporated by reference; post-effective amendments.
 
     The undersigned Registrant hereby undertakes to respond to requests for
information that is incorporated by reference into the prospectus pursuant to
Items 4, 10(b), 11 or 13 of Form S-4, within one business day of receipt of such
request, and to send the incorporated documents by first class mail or other
equally prompt means. This includes information contained in documents filed
subsequent to the effective date of the Registration Statement through the date
of responding to the request.
 
     The undersigned Registrant hereby undertakes to supply by means of a
post-effective amendment all information concerning a transaction, and the
company being acquired involved therein, that was not the subject of and
included in the Registration Statement when it became effective.
 
                                      II-4
<PAGE>   151
 
                                   SIGNATURES
 
     Pursuant to the requirements of the Securities Act of 1933, the Registrant
has duly caused this Registration Statement to be signed on its behalf by the
undersigned, thereunto duly authorized, in the City of Houston, State of Texas,
on the 8th day of July, 1994.
 
                                            NOBLE DRILLING CORPORATION
 
                                            By:     /s/  JAMES C. DAY
                                               --------------------------------
                                                         James C. Day
                                                Chairman, President and Chief
                                                       Executive Officer
 
     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the dates indicated. Each person whose signature appears below
constitutes and appoints James C. Day and Byron L. Welliver, and each of them
(with full power to each of them to act alone), his true and lawful
attorney-in-fact and agent, with full power of substitution and resubstitution,
for him and in his name, place and stead, in any and all capacities to sign on
his behalf individually and in each capacity stated below any amendment,
including post-effective amendments, to this Registration Statement, and to file
the same, with all exhibits thereto and other documents in connection therewith
with the Securities and Exchange Commission, granting unto said
attorneys-in-fact and agents, and each of them, full power and authority to do
and perform each and every act and thing requisite and necessary to be done in
and about the premises, as fully to all intents and purposes as he might or
could do in person, hereby ratifying and confirming all that said
attorneys-in-fact and agents and either of them, or their substitutes, may
lawfully do or cause to be done by virtue hereof.
 
<TABLE>
<CAPTION>
                  SIGNATURE                               TITLE                     DATE
- ---------------------------------------------  ----------------------------    --------------
<S>                                            <C>                             <C>
              /s/  JAMES C. DAY                Chairman, President and           July 8, 1994
     -----------------------------------         Chief Executive Officer
                   James C. Day                  and Director (Principal
                                                 Executive Officer)
                                                 

           /s/  BYRON L. WELLIVER              Senior Vice President --          July 8, 1994
     -----------------------------------         Finance and Treasurer
                Byron L. Welliver                (Principal Financial
                                                 Officer)
                                                 

             /s/  ALAN KRENEK                 Controller (Principal             July 8, 1994
     -----------------------------------          Accounting Officer)
                  Alan Krenek                     

     -----------------------------------         
              Michael A. Cawley                Director

          /s/  TOMMY C. CRAIGHEAD              Director                          July 8, 1994
     -----------------------------------
               Tommy C. Craighead

          /s/  JOHNNIE W. HOFFMAN              Director                          July 8, 1994
     -----------------------------------
               Johnnie W. Hoffman

     -----------------------------------       Director
               James L. Fishel

           /s/  JOHN F. SNODGRASS              Director                          July 8, 1994
     -----------------------------------
                John F. Snodgrass

            /s/  BILL M. THOMPSON              Director                          July 8, 1994
     -----------------------------------
                 Bill M. Thompson
</TABLE>
 
                                      II-5
<PAGE>   152
 
                               INDEX TO EXHIBITS
 
<TABLE>
<CAPTION>
       NUMBER                                          EXHIBIT
       ------                                          -------
           <S>          <C>
           2.1*         -- Agreement and Plan of Merger dated as of June 13, 1994, among Noble
                           Drilling Corporation, Noble Offshore Corporation and Chiles
                           Offshore Corporation (included as Appendix I to the Joint Proxy
                           Statement/Prospectus forming a part of this Registration
                           Statement).
           2.2          -- Stock Purchase Agreement dated April 22, 1994, between Joseph E.
                           Beall, George H. Bruce, Triton Engineering Services Company and
                           Noble Drilling Corporation (filed as Exhibit 2.1 to Noble Drilling
                           Corporation's Form 8-K dated May 6, 1994 and incorporated herein by
                           reference).
           2.3          -- Assets Purchase Agreement dated as of August 20, 1993 (the "Western
                           Assets Purchase Agreement"), between Noble Drilling Corporation and
                           The Western Company of North America (filed as Exhibit 2.1 to Noble
                           Drilling Corporation's Registration Statement on Form S-3 (No.
                           33-67130) and incorporated herein by reference).
           2.4          -- Agreement dated as of October 7, 1993, among Noble Drilling
                           Corporation, Noble Drilling (U.S.) Inc., Noble International
                           Limited, The Western Company of North America and Offshore
                           International Ltd., amending the Western Assets Purchase Agreement
                           (filed as Exhibit 2.2 to Noble Drilling Corporation's Form 8-K
                           dated October 15, 1993 and incorporated herein by reference).
           2.5          -- Exchange Agreement dated as of June 4, 1993 (the "Exchange
                           Agreement"), by and among Noble Drilling Corporation, Grasso
                           Corporation, Offshore Logistics, Inc., PPI-Seahawk Services, Inc.
                           and Noble Production Services Inc. (filed as Exhibit 2.2 to Noble
                           Drilling Corporation's Registration Statement on Form S-3 (No.
                           33-67130) and incorporated herein by reference).
           2.6          -- Amendment No. 1 dated October 29, 1993 to the Exchange Agreement by
                           and among Noble Drilling Corporation, Grasso Corporation, Offshore
                           Logistics, Inc., PPI-Seahawk Services, Inc. and Noble Production
                           Services Inc. (filed as Exhibit 2.4 to Noble Drilling Corporation's
                           Annual Report on Form 10-K for the year ended December 31, 1993 and
                           incorporated herein by reference).
           2.7          -- Assignment and Assumption Agreement made as of October 28, 1993, by
                           and between Noble Production Management Inc., Noble Production
                           Services Inc., OLOG Production Management Inc., PPI-Seahawk
                           Services, Inc. and Grasso Corporation (filed as Exhibit 2.7 to
                           Noble Drilling Corporation's Annual Report on Form 10-K for the
                           year ended December 31, 1993 and incorporated herein by reference).
           2.8          -- Assets Purchase Agreement dated as of August 20, 1993 (the "Portal
                           Assets Purchase Agreement"), between Noble Drilling Corporation and
                           Portal Rig Corporation (filed as Exhibit 2.3 to Noble Drilling
                           Corporation's Registration Statement on Form S-3 (No. 33-67130) and
                           incorporated herein by reference).
           2.9          -- Agreement dated as of October 25, 1993, among Noble Drilling
                           Corporation, Noble (Gulf of Mexico) Inc. and Portal Rig
                           Corporation, amending the Portal Assets Purchase Agreement (filed
                           as Exhibit 2.5 to Noble Drilling Corporation's Quarterly Report on
                           Form 10-Q for the three-month period ended September 30, 1993 and
                           incorporated herein by reference).
           4.1          -- Restated Certificate of Incorporation of Noble Drilling Corporation
                           dated August 29, 1985 (filed as Exhibit 3.7 to Noble Drilling
                           Corporation's Registration Statement on Form 10 (No. 0-13857) and
                           incorporated herein by reference).
</TABLE>
<PAGE>   153
 
<TABLE>
<CAPTION>
         NUMBER                                          EXHIBIT
         ------                                          -------
          <S>           <C>         
           4.2          -- Certificate of Amendment of Restated Certificate of Incorporation
                           of Noble Drilling Corporation dated May 5, 1987 (filed as Exhibit
                           4.2 to Noble Drilling Corporation's Registration Statement on Form
                           S-3 (No. 33-67130) and incorporated herein by reference).
           4.3          -- Certificate of Amendment of Restated Certificate of Incorporation
                           of Noble Drilling Corporation dated June 1, 1987 (filed as Exhibit
                           4.3 to Noble Drilling Corporation's Registration Statement on Form
                           S-3 and incorporated herein by reference).
           4.4          -- Certificate of Amendment of Restated Certificate of Incorporation
                           of Noble Drilling Corporation dated April 28, 1988 (filed as
                           Exhibit 3.12 to Noble Drilling Corporation's Annual Report on Form
                           10-K for the year ended December 31, 1988 and incorporated herein
                           by reference).
           4.5          -- Certificate of Amendment of Restated Certificate of Incorporation
                           of Noble Drilling Corporation dated April 27, 1989 (filed as
                           Exhibit 3.13 to Noble Drilling Corporation's Annual Report on Form
                           10-K for the year ended December 31, 1989, as amended, and
                           incorporated herein by reference).
           4.6          -- Certificate of Amendment of Restated Certificate of Incorporation
                           of Noble Drilling Corporation dated August 1, 1991 (filed as
                           Exhibit 3.16 to Noble Drilling Corporation's Annual Report on Form
                           10-K for the year ended December 31, 1991 and incorporated herein
                           by reference).
           4.7          -- Certificate of Designations of $2.25 Convertible Exchangeable
                           Preferred Stock, par value $1.00 per share, of Noble Drilling
                           Corporation, dated as of November 18, 1991 (filed as Exhibit 3.17
                           to Noble Drilling Corporation's Annual Report on Form 10-K for the
                           year ended December 31, 1991 and incorporated herein by reference).
           4.8**        -- Form of Certificate of Designations of $1.50 Convertible Preferred
                           Stock, par value $1.00 per share, of Noble Drilling Corporation.
           4.9*         -- Form of certificate to evidence shares of $1.50 Convertible
                           Preferred Stock of Noble Drilling Corporation.
           4.10         -- Composite copy of the Bylaws of Noble Drilling Corporation as
                           currently in effect (filed as Exhibit 4.8 to Noble Drilling
                           Corporation's Registration Statement on Form S-3 (No. 33-67130) and
                           incorporated herein by reference).
           4.11         -- Indenture governing the 9 1/4% Senior Notes Due 2003 of Noble
                           Drilling Corporation (filed as Exhibit 4.1 to Noble Drilling
                           Corporation's Quarterly Report on Form 10-Q for the three-month
                           period ended September 30, 1993 and incorporated herein by
                           reference).
           4.12         -- Form of Senior Notes (included in Section 2.02 of the Indenture
                           filed as Exhibit 4.1 to Noble Drilling Corporation's Quarterly
                           Report on Form 10-Q for the three-month period ended September 30,
                           1993 and incorporated herein by reference).
           5.1**        -- Opinion of Thompson & Knight, A Professional Corporation.
           8.1**        -- Opinion of Thompson & Knight, A Professional Corporation.
</TABLE>
<PAGE>   154
 
<TABLE>
<CAPTION>
       NUMBER                                          EXHIBIT
       ------                                          -------
         <S>           <C>
          10.1*         -- Credit Agreement dated as of June 16, 1994 among Noble Drilling
                           Corporation, First Interstate Bank of Texas, N.A., in its
                           individual capacity and as agent, and Credit Lyonnais Cayman Island
                           Branch.
          10.2*         -- Revolving Credit Note dated June 16, 1994 of Noble Drilling
                           Corporation in the amount of $12,500,000 in favor of Credit
                           Lyonnais Cayman Island Branch.
          10.3*         -- Revolving Credit Note dated June 16, 1994 of Noble Drilling
                           Corporation in the amount of $12,500,000 in favor of First
                           Interstate Bank of Texas, N.A.
          10.4*         -- Guaranty Agreement dated as of June 16, 1994 by and among Noble
                           Drilling (U.S.) Inc., Noble Drilling (West Africa) Inc. and Noble
                           Drilling (Mexico) Inc.
          12.1*         -- Statement regarding computation of ratios.
          23.1*         -- Consent of Arthur Andersen & Co.
          23.2*         -- Consent of Arthur Andersen & Co.
          23.3*         -- Consent of KPMG Peat Marwick.
          23.4**        -- Consent of Thompson & Knight, A Professional Corporation (contained
                           in its opinion to be filed as Exhibit 5.1).
          23.5**        -- Consent of Thompson & Knight, A Professional Corporation (contained
                           in its opinion to be filed as Exhibit 8.1).
          23.6*         -- Consent of Simmons & Company International.
          23.7*         -- Consent of Salomon Brothers Inc .
          24.1*         -- Power of attorney (included on the signature page of this
                           Registration Statement).
          99.1*         -- Form of Proxy of Noble Drilling Corporation (relating to the
                           Special Meeting of the stockholders of Noble Drilling Corporation
                           described in the Joint Proxy Statement/Prospectus forming a part of
                           this Registration Statement).
          99.2*         -- Form of Proxy of Chiles Offshore Corporation (relating to the
                           Special Meeting of the stockholders of Chiles Offshore Corporation
                           described in the Joint Proxy Statement/Prospectus forming a part of
                           this Registration Statement).
</TABLE>
 
- ---------------
 
 * Filed herewith.
** To be filed by amendment.

<PAGE>   1
                                                                  EXHIBIT 4.9


 INCORPORATED UNDER THE                                       $1.50 CONVERTIBLE 
  LAWS OF THE STATE OF                                         PREFERRED STOCK
        DELAWARE



         NUMBER                                                     SHARES 
NP                               [NOBLE LOGO]



  THIS CERTIFICATE IS      NOBLE DRILLING CORPORATION               CUSIP 
   TRANSFERRABLE IN
OKLAHOMA CITY, OKLAHOMA                                        SEE REVERSE FOR 
 OR NEW YORK, NEW YORK                                       CERTAIN STATEMENTS,
                                                               RESTRICTIONS AND
                                                                  DEFINITIONS




THIS CERTIFIES THAT                                  is the owner of
FULLY PAID AND NON-ASSESSABLE SHARES OF $1.50 CONVERTIBLE PREFERRED STOCK, PAR
VALUE $1.00 PER SHARE, OF NOBLE DRILLING CORPORATION transferable on the books
of the Corporation by the holder hereof, in person or by duly authorized
attorney, upon surrender of this Certificate properly endorsed or accompanied
by a proper assignment.  This Certificate and the shares represented hereby are
issued and shall be held subject to all of the provisions of the Certificate of
Incorporation and the Bylaws of the Corporation, and all amendments thereto,
copies of which are on file at the principal office of the Corporation, to all
of which the holder of this Certificate by acceptance hereof assents.  This
Certificate is not valid until countersigned and registered by the Transfer
Agent and Registrar.

        IN WITNESS WHEREOF, the Corporation has caused the signatures of its
duly authorized officers and its facsimile seal to be hereunto affixed.

                                           DATED:

/s/  JAMES C. DAY
CHAIRMAN, PRESIDENT AND                    COUNTERSIGNED AND REGISTERED:
CHIEF EXECUTIVE OFFICER                        LIBERTY BANK AND TRUST
                                                COMPANY OF OKLAHOMA
                                                     CITY, N.A.


                            [NOBLE CORPORATE SEAL]                TRANSFER AGENT
                                                                   AND REGISTRAR


/s/  JULIE J. ROBERTSON
            SECRETARY                                       AUTHORIZED SIGNATURE
<PAGE>   2
                                  [NOBLE LOGO]

                           NOBLE DRILLING CORPORATION

         THE CORPORATION WILL FURNISH WITHOUT CHARGE TO EACH STOCKHOLDER WHO SO
REQUESTS THE POWERS, DESIGNATIONS, PREFERENCES AND RELATIVE, PARTICIPATING,
OPTIONAL OR OTHER SPECIAL RIGHTS OF EACH CLASS OF STOCK OR SERIES THEREOF OF
THE CORPORATION, AND THE QUALIFICATIONS, LIMITATIONS OR RESTRICTIONS OF SUCH
PREFERENCES AND/OR RIGHTS.

         THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO CERTAIN
RESTRICTIONS ON TRANSFER SET FORTH IN ARTICLE XI OF THE CORPORATION'S
CERTIFICATE OF INCORPORATION.  THE PURPOSE OF SAID ARTICLE XI IS TO LIMIT THE
OWNERSHIP AND CONTROL OF SHARES OF ANY CLASS OF STOCK OF THE CORPORATION BY
ALIENS (AS DEFINED) IN ORDER TO PERMIT THE CORPORATION TO BE A U.S. MARITIME
COMPANY (AS DEFINED).  THE CORPORATION WILL FURNISH WITHOUT CHARGE TO EACH
STOCKHOLDER WHO SO REQUESTS A COPY OF SAID ARTICLE XI.

         The following abbreviations, when used in the inscription on the face
of this certificate, shall be construed as though they were written out in full
according to applicable laws or regulations:

TEN COM -- as tenants in common   UNIF GIFT MIN ACT -- _____ Custodian _________
TEN ENT -- as tenants by the                           (Cust)          (Minor)
           entireties                                  under Uniform Gifts to
JT TEN  -- as joint tenants with                       Minors Act _____________
           right of survivorship                                    (State)
           and not as tenants                          
           in common

         Additional abbreviations may also be used though not in the above list.

         For value received, ____________________________________ hereby sell,
assign and transfer unto
PLEASE INSERT SOCIAL SECURITY OR OTHER
IDENTIFYING NUMBER OF ASSIGNEE

[Box]___________________________________________________________________________

________________________________________________________________________________
PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS INCLUDING POSTAL ZIP CODE OF ASSIGNEE

________________________________________________________________________________
Shares of the stock represented by the within Certificate, and do hereby 
irrevocably  constitute and appoint_____________________________________________

________________________________________________________________________________
Attorney to transfer the said Shares on the books of the within-named
Corporation with full power of substitution in the premises.

Dated, __________________
                                        ________________________________________
                                        NOTICE:  The signature to this 
                                        Assignment must correspond with the 
                                        name as written upon the face of the
                                        certificate, in every particular, 
                                        without alteration or enlargement, or 
                                        any change whatever.
 



<PAGE>   1





                                CREDIT AGREEMENT

                                  by and among

                     FIRST INTERSTATE BANK OF TEXAS, N. A.,
                                   AS AGENT,

                                 CERTAIN BANKS

                                      and

                           NOBLE DRILLING CORPORATION


                           Dated as of June 16, 1994
<PAGE>   2
                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                        Page
                                                                                        ----
<S>      <C>     <C>                                                                    <C>
ARTICLE I -- DEFINITIONS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1
         1.01    Certain Definitions  . . . . . . . . . . . . . . . . . . . . . . . . .   1
         1.02    Accounting Terms and Definitions . . . . . . . . . . . . . . . . . . .  29
                                                                                
ARTICLE II -- CREDIT FACILITIES . . . . . . . . . . . . . . . . . . . . . . . . . . . .  29
         2.01    Extensions of Credit . . . . . . . . . . . . . . . . . . . . . . . . .  29
         2.02    Extensions of Maturity . . . . . . . . . . . . . . . . . . . . . . . .  30
         2.03    Manner of Borrowing  . . . . . . . . . . . . . . . . . . . . . . . . .  31
         2.04    Conversions and Continuations  . . . . . . . . . . . . . . . . . . . .  33
         2.05    Use of Proceeds of Advances  . . . . . . . . . . . . . . . . . . . . .  34
         2.06    Fees . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  34
         2.07    Reduction or Termination of Revolving Credit Commitment  . . . . . . .  35
         2.08    Letters of Credit  . . . . . . . . . . . . . . . . . . . . . . . . . .  35
         2.09    Notice and Manner of Obtaining Letters of Credit . . . . . . . . . . .  36
         2.10    Obligation to Reimburse and to Prepay  . . . . . . . . . . . . . . . .  37
         2.11    Method of Payment  . . . . . . . . . . . . . . . . . . . . . . . . . .  38
         2.12    Prepayment; Compensation . . . . . . . . . . . . . . . . . . . . . . .  38
         2.13    Computation of Interest  . . . . . . . . . . . . . . . . . . . . . . .  39
         2.14    Increased Costs; Regulation  . . . . . . . . . . . . . . . . . . . . .  39
         2.15    Limitation on Types of Advances  . . . . . . . . . . . . . . . . . . .  41
         2.16    Substitute Base Rate Advances  . . . . . . . . . . . . . . . . . . . .  42
         2.17    The Facilities . . . . . . . . . . . . . . . . . . . . . . . . . . . .  42
                                                                                
ARTICLE III -- REPRESENTATIONS AND WARRANTIES . . . . . . . . . . . . . . . . . . . . .  43
         3.01    Legal Existence  . . . . . . . . . . . . . . . . . . . . . . . . . . .  43
         3.02    Corporate Power and Authority to Execute Documents . . . . . . . . . .  43
         3.03    Direct Benefit From Loans  . . . . . . . . . . . . . . . . . . . . . .  44
         3.04    Valid, Binding, Enforceable Obligations  . . . . . . . . . . . . . . .  44
         3.05    No Violation of Charter, By-Laws or Agreements . . . . . . . . . . . .  44
         3.06    No Violation of Laws, Rules or Orders  . . . . . . . . . . . . . . . .  44
         3.07    Loan Documents Do Not Violate Other Documents  . . . . . . . . . . . .  45
         3.08    Board of Directors Authorization . . . . . . . . . . . . . . . . . . .  45
         3.09    Financial Statements . . . . . . . . . . . . . . . . . . . . . . . . .  45
         3.10    No Undisclosed Liabilities . . . . . . . . . . . . . . . . . . . . . .  45
         3.11    Tax Returns and Payments . . . . . . . . . . . . . . . . . . . . . . .  46
         3.12    ERISA  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  46
         3.13    Environmental Laws . . . . . . . . . . . . . . . . . . . . . . . . . .  46
         3.14    Subsidiaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  47
         3.15    Not a Secured Purpose Credit . . . . . . . . . . . . . . . . . . . . .  47
         3.16    Investments and Obligations  . . . . . . . . . . . . . . . . . . . . .  47
         3.17    Consents Not Required  . . . . . . . . . . . . . . . . . . . . . . . .  47
         3.18    Litigation Pending . . . . . . . . . . . . . . . . . . . . . . . . . .  47
</TABLE>                                                                        





                                       i
<PAGE>   3
<TABLE>
<CAPTION>
                                                                                        Page 
                                                                                        ---- 
<S>      <C>     <C>                                                                    <C>  
         3.19    Material Fact Representations  . . . . . . . . . . . . . . . . . . . .  48  
         3.20    Borrower's Status  . . . . . . . . . . . . . . . . . . . . . . . . . .  48  
                                                                                             
ARTICLE IV -- AFFIRMATIVE COVENANTS . . . . . . . . . . . . . . . . . . . . . . . . . .  48  
         4.01    Reporting Obligations  . . . . . . . . . . . . . . . . . . . . . . . .  48  
         4.02    Payment of Taxes and Claims  . . . . . . . . . . . . . . . . . . . . .  51  
         4.03    Maintenance of Existence, Property and Records . . . . . . . . . . . .  51  
         4.04    Compliance With Laws . . . . . . . . . . . . . . . . . . . . . . . . .  52  
         4.05    Cure of Defects in Loan Documents  . . . . . . . . . . . . . . . . . .  52  
         4.06    Payment of Expenses  . . . . . . . . . . . . . . . . . . . . . . . . .  53  
         4.07    Inspection of Books, Property and Affairs  . . . . . . . . . . . . . .  53  
         4.08    Insurance  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  53  
         4.09    Payment of Fees  . . . . . . . . . . . . . . . . . . . . . . . . . . .  54  
         4.10    Cash Management  . . . . . . . . . . . . . . . . . . . . . . . . . . .  54  
         4.11    Guarantees and Notes . . . . . . . . . . . . . . . . . . . . . . . . .  54  
                                                                                             
ARTICLE V -- NEGATIVE COVENANTS . . . . . . . . . . . . . . . . . . . . . . . . . . . .  54  
         5.01    Limitations on Funded Debt . . . . . . . . . . . . . . . . . . . . . .  55  
         5.02    Limitations on Liens . . . . . . . . . . . . . . . . . . . . . . . . .  55  
         5.03    Restricted Payments  . . . . . . . . . . . . . . . . . . . . . . . . .  55  
         5.04    ERISA Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  55  
         5.05    Coverage Ratios  . . . . . . . . . . . . . . . . . . . . . . . . . . .  56  
         5.06    Tangible Net Worth . . . . . . . . . . . . . . . . . . . . . . . . . .  56  
         5.07    Leverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  56  
         5.08    Limitations on Investments . . . . . . . . . . . . . . . . . . . . . .  56  
         5.09    Subsidiary Stock Issuances, Charter Documents and Business                  
                   Termination  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  56  
         5.10    Mergers and Acquisitions . . . . . . . . . . . . . . . . . . . . . . .  57  
         5.11    Changes in Accounting Methods  . . . . . . . . . . . . . . . . . . . .  57  
         5.12    Changes in Business or Assets  . . . . . . . . . . . . . . . . . . . .  57  
         5.13    Discounting of Receivables . . . . . . . . . . . . . . . . . . . . . .  58  
         5.14    Transactions with Affiliates . . . . . . . . . . . . . . . . . . . . .  58  
         5.15    Limitation on Subsidiary Indebtedness and Preferred Stock  . . . . . .  58  
         5.16    Loan Proceeds  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  59  
         5.17    Limitation on Dividends and Other Payment Restrictions Affecting            
                   Subsidiaries . . . . . . . . . . . . . . . . . . . . . . . . . . . .  59  
         5.18    Limitation on Asset Sales  . . . . . . . . . . . . . . . . . . . . . .  60  
         5.19    Limitation on Sale and Lease-Back Transactions . . . . . . . . . . . .  60  
                                                                                             
ARTICLE VI -- DEFAULTS AND REMEDIES . . . . . . . . . . . . . . . . . . . . . . . . . .  60  
         6.01    Events of Default  . . . . . . . . . . . . . . . . . . . . . . . . . .  60  
         6.02    Cash Collateral Account  . . . . . . . . . . . . . . . . . . . . . . .  64  
         6.03    Additional Cross Default Provisions  . . . . . . . . . . . . . . . . .  64  
</TABLE>                                                       
                                                               
                                                               
                                                               
                                           ii                  
                                                               
                                                               
                                                               
                                                               
                                                               
<PAGE>   4
<TABLE>                                                              
<CAPTION>                                                                   

                                                                                          Page
                                                                                          ----
<S>      <C>   <C>                                                                        <C> 
ARTICLE VII -- TERMINATION OF LOANS . . . . . . . . . . . . . . . . . . . . . . . . . . .  65 
                                                                                              
ARTICLE VIII -- CONDITIONS PRECEDENT  . . . . . . . . . . . . . . . . . . . . . . . . . .  65 
         8.01    Conditions Precedent to Initial Loan . . . . . . . . . . . . . . . . . .  65 
         8.02    Conditions Precedent to Each Loan  . . . . . . . . . . . . . . . . . . .  67 
                                                                                              
ARTICLE IX -- THE AGENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  67 
         9.01    Authorization and Action . . . . . . . . . . . . . . . . . . . . . . . .  67 
         9.02    Agent's Reliance, Etc  . . . . . . . . . . . . . . . . . . . . . . . . .  69 
         9.03    First Interstate Bank and Affiliates . . . . . . . . . . . . . . . . . .  69 
         9.04    Lender Credit Decision . . . . . . . . . . . . . . . . . . . . . . . . .  69 
         9.05    Indemnification by Lenders . . . . . . . . . . . . . . . . . . . . . . .  70 
         9.06    Successor Agent  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  70 
                                                                                              
ARTICLE X -- MISCELLANEOUS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  71 
         10.01   No Waivers Except by Writing; Governing Law  . . . . . . . . . . . . . .  71 
         10.02   Usury Laws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  72 
         10.03   Notice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  73 
         10.04   Waivers of Certain Rights  . . . . . . . . . . . . . . . . . . . . . . .  73 
         10.05   Severability of Provisions . . . . . . . . . . . . . . . . . . . . . . .  75 
         10.06   Survival of Representations and Warranties; Unsatisfied Conditions . . .  75 
         10.07   Assignments  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  75 
         10.08   Gender and Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . .  77 
         10.09   Multiple Counterparts  . . . . . . . . . . . . . . . . . . . . . . . . .  77 
         10.10   Notices Received by Lender . . . . . . . . . . . . . . . . . . . . . . .  77 
         10.11   Debtor-Creditor Relationship . . . . . . . . . . . . . . . . . . . . . .  77 
         10.12   Agreement Controlling  . . . . . . . . . . . . . . . . . . . . . . . . .  77 
         10.13   Integration  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  77 
         10.14   WAIVER OF JURY TRIAL . . . . . . . . . . . . . . . . . . . . . . . . . .  78 
         10.15   Headings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  78 
         10.16   Submission to Jurisdiction . . . . . . . . . . . . . . . . . . . . . . .  78 
         10.17   Additional Liens . . . . . . . . . . . . . . . . . . . . . . . . . . . .  79 
         10.18   Bank Representations . . . . . . . . . . . . . . . . . . . . . . . . . .  79 
         10.19   Indemnification  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  80 
</TABLE>                                                                    

Schedule 1       -     Liens on Property of the Borrower or its Subsidiaries
Schedule 3.10    -     Liabilities                                          
Schedule 3.12    -     ERISA Matters                                        
Schedule 3.14    -     List of Subsidiaries                                 
Schedule 5.17    -     Restrictions on Intercompany Transfers               
                                                                            
Exhibit A        -     Revolving Note                                       
Exhibit B        -     Applications for Letters of Credit                   
Exhibit C        -     Assignment and Acceptance                            





                                            iii                                
                                                                            
                                                                            
                                                                            
                                                                            
                                                                            
<PAGE>   5
Exhibit D        -        Guaranty Agreement
Exhibit E        -        Intercompany Revolving Note
Exhibit F        -        Loan Formula Certificate
Exhibit G        -        Loan Request Form
Exhibit H        -        Quarterly Compliance Certificate





                                       iv
<PAGE>   6

                                CREDIT AGREEMENT



         THIS CREDIT AGREEMENT dated and effective as of June 16, 1994
(together with any and all amendments and supplements hereto and/or
restatements and modifications hereof, collectively referred to hereinafter as
the "Agreement"), by and among FIRST INTERSTATE BANK OF TEXAS, N. A., a
national banking association in its individual capacity and as agent for the
Banks (as hereinafter defined), each of the Banks party hereto listed on the
signature pages of this Agreement, and NOBLE DRILLING CORPORATION, a Delaware
corporation (the "Borrower").

                              W I T N E S S E T H:

         WHEREAS, each of the Borrower and its Subsidiaries have requested the
Banks to make certain loans to the Borrower for the purposes stated herein,
which loans are for the benefit of the Borrower and its Subsidiaries;

         WHEREAS, each of the Subsidiaries will benefit from the credit
facilities made available hereunder, and will have substantially improved
growth prospects because of such facilities; and

         WHEREAS, the Banks are willing to make such loans as herein provided,
upon the terms, agreements and covenants and subject to the conditions
hereinafter set forth and in reliance on the representations and warranties
herein made and referred to;

         NOW THEREFORE, to induce the Banks to make available the credit
facilities herein described and referenced, and for and in consideration of the
premises, covenants and agreements herein contained, in reliance on the
representations and warranties herein made, and for other good and valuable
considerations and reasonably equivalent value, the receipt and sufficiency of
which are hereby acknowledged by the parties hereto, the Agent, the Banks and
the Borrower agree as follows:

                            ARTICLE I -- DEFINITIONS

         1.01    Certain Definitions.  As used in this Agreement, the following
terms shall have the respective meanings indicated below:

         "Adjusted Eurodollar Rate" means, for any Eurodollar Advance during
any Interest Period therefor the rate per annum (rounded upwards, if necessary,
to the nearest 1/100 of 1%) determined by the Agent to be equal to the
Eurodollar Rate for such Eurodollar Advance for such Interest Period divided by
one minus the Reserve Requirement for such Eurodollar Advance in effect on the
first day of such Interest Period.  The Adjusted Eurodollar Rate shall be
computed on the basis of an actual number of days elapsed in a year consisting
of 360 days.
<PAGE>   7
         "Advance" means any advance of funds by the Banks to the Borrower
pursuant to this Agreement, and after each initial advance thereof, any portion
thereof remaining outstanding and unpaid; and each advance of funds by the
Banks to the Borrower for a particular selected Interest Period (except for
such Advances for which an Interest Period need not be specified), shall
constitute one "Advance" for purposes of determining the number of "Advances"
outstanding hereunder.

         "Affiliate" means any Person controlling, controlled by or under
common control with any other Person. For purposes of this definition "control"
(including "controlled by" and "under common control with") means the
possession, directly or indirectly, of the power to direct or cause the
direction of the management and policies of such Person, whether through the
ownership of voting securities or otherwise.  Without limiting the generality
of the foregoing, for purposes of this Agreement the Borrower and each of its
Subsidiaries shall be deemed to be Affiliates of each other.

         "Agent" means First Interstate Bank of Texas, National Association, in
its capacity as agent for the Banks pursuant to Article IX hereof, and not in
its individual capacity as a Bank, and any successor Agent appointed pursuant
to Article IX hereof.

         "Agent Fee" means the fee payable to First Interstate, provided in
that certain letter from the Borrower to First Interstate dated April 5, 1994.

         "Agreement" shall have the meaning assigned to that term in the
introduction hereto, and "Agreement", "hereof", "hereto" and "hereunder" and
words of similar import mean this Agreement as a whole, and not any particular
article, section or subsection.

         "Applicable Law" means the law in effect from time to time and
applicable to the transactions between the Banks and the Borrower (and, to the
extent applicable, the Significant Subsidiaries) pursuant to this Agreement,
the Notes and the other Loan Documents which lawfully permits the charging and
collection of the highest permissible lawful nonusurious rate of interest on
such transactions, including laws of the State of Texas, and to the extent
controlling, laws of the United States of America.  It is intended that Article
1.04, Title 79, Revised Civil Statutes of Texas, 1925, as amended, shall be
included in the laws of the State of Texas in determining Applicable Law; and
for the purpose of applying said Article 1.04, the interest ceiling applicable
to such transactions under said Article 1.04 shall be the indicated (weekly)
rate ceiling from time to time in effect.

         "Applicable Lending Office" means for each of the Banks, (i) for each
Type of Advance, the lending office designated for such Type of Advance below
each such Bank's name on the signature pages hereof or such other office of
each such Bank as each such Bank may from time to time specify to the Borrower
as the office by which its Advances of such Type are to be made and maintained.

         "Applicable Margin" means, for any Advance and on any day, and
effective as of the first day upon which the Agent shall have received the
financial statements and other information required to be delivered to the
Agent in Sections 4.01(a) and (c) hereof ("Current Information"),





                                       2
<PAGE>   8
and continuing in effect until new Current Information is received by Agent,
the sum of (i) the Operating Loss Increment, plus (ii) the per annum rate
provided in the intersection, in the following table, of (a) the Special
Purpose Fixed Charge Coverage Ratio for the four Quarterly Reporting Periods,
for which Current Information is available at the date of calculation of
Applicable Margin, immediately preceding the date of calculation of the
Applicable Margin and (b) the Type of Advance for which the Applicable Margin
is to be calculated:

<TABLE>
<CAPTION>
                                                               For a                         For a
           Special Purpose Fixed Charge                     Eurodollar                     Base Rate
              Charge Coverage Ratio                           Advance                       Advance
              ---------------------                           -------                       -------
 <S>                                                      <C>                          <C>
 (a) At least 1.51                                        1.50% per annum                0% per annum
 (b) At least 1.26 but less than 1.51                     1.75% per annum                0% per annum

 (c) Less than 1.26                                       2.0% per annum                .25% per annum
</TABLE>

; provided, that the Applicable Margin shall be fixed at 1.5% for Eurodollar
Advances, and shall be zero for Base Rate Advances, through December 31, 1994.

         "Applicable Rate" means, during the period that (i) an Advance is a
Eurodollar Advance, the Adjusted Eurodollar Rate, and (ii) an advance is a Base
Rate Advance, the Base Rate.

         "Application"  means the Application for an Irrevocable Standby Letter
of Credit, or the Application and Agreement for Commercial Letter of Credit, as
applicable, in form and substance substantially similar to that which is
attached hereto as Exhibit B, with the blanks therein properly and accurately
completed.

         "Asset Sale" means any direct or indirect sale, conveyance, transfer,
lease or other disposition (including, without limitation, by means of a Sale
and Lease-Back Transaction or by way of merger or consolidation) by the
Borrower or any Subsidiary to any Person other than the Borrower or a
Subsidiary, in one transaction, or a series of related transactions, of (i) any
capital stock of any Subsidiary, or (ii) any other Property or assets of the
Borrower or any Subsidiary, other than (A) sales of inventory of the Borrower
and the subsidiaries in the ordinary course of their business consistent with
past practices, (B) sales of obsolete or worn out equipment in the ordinary
course of business, (C) sales of directors' qualifying shares in a Subsidiary,
(D) any charter (bare-boat or otherwise) or other lease of Property entered
into by the Borrower or any Subsidiary in the ordinary course of business,
other than any charter or lease that provides for acquisition of such Property
by the charterer or lessee during or at the end of the term thereof, (E) the
issuance by the Borrower of its capital stock, (F) sales in the ordinary course
of business of drill pipe and associated equipment utilized in connection with
a drilling contract for the employment of a drilling rig, (G) a Restricted
Payment permitted by Section 5.03 hereof and (H) sales of the Grasso
Consideration (as defined in the Grasso Agreement) and any securities or
property acquired upon the exercise of the options or warrants included as a
part of the Grasso Consideration.  An Asset Sale shall include the requisition
of title to, seizure of or forfeiture of any Property or assets, or any actual
or constructive total loss or an agreed or compromised total loss of any
Property or assets.





                                       3
<PAGE>   9
         "Assignment and Acceptance" shall mean an assignment and acceptance
entered into by any of the Banks and an Eligible Assignee, and accepted by
Agent in a form of Exhibit C.

         "Authorized Representative" means the president or any vice president
or any senior or executive vice president with respect to the Borrower or any
Subsidiary thereof, as applicable.

         "Average Life" means, as of any date, with respect to any debt
security, the quotient obtained by dividing (i) the sum of the products of (x)
the number of years from such date to the date of each scheduled principal
payment (including any sinking fund or mandatory redemption payment
requirements) of such debt security multiplied in each case by (y) the amount
of such principal payments by (ii) the sum of all such principal payments.

         "Banks" means each of the lenders listed on the signature pages of
this Agreement, and each assignee thereof which becomes a party to this
Agreement pursuant to Section 10.07 hereof.

         "Base Rate" means, at the time any determination thereof is to be
made, the greater of (a) the fluctuating per annum rate of interest then most
recently announced by Agent in Houston, Texas as its prime rate, and (b) the
sum of the Federal Funds Rate plus .5% per annum.  The prime rate is a rate set
by Agent based upon various factors, including Agent's costs and desired
return, general economic conditions and other factors, and is used as a
reference point for pricing some loans.  Agent may price loans at, above or
below the prime rate.  Any change in the prime rate shall take effect hereunder
as of and on the opening of business on the date specified in the announcement
of such change.  A certificate in writing by any vice president of Agent as to
the prime rate as of any date or dates shall be prima facie evidence of such
fact.

         "Base Rate Advance" means any Advance that bears interest at a rate
based upon the Base Rate.  Changes in the rate of interest on Base Rate
Advances will take effect simultaneously with each change in the Base Rate.

         "Borrower" shall have the meaning assigned to that term in the 
introduction to this Agreement.

         "Borrowing Base" means, as of any time the determination thereof is to
be made, an amount equal to 75% of Eligible Accounts.

         "Borrowing Date" means a date upon which a Revolving Loan is to be
made pursuant to Section 2.03 hereof as established by the Loan Request Form.

         "Business Day" means (i) any day on which commercial banks are not
authorized or required to close in either Houston, Texas, or New York, New York
and (ii) with respect to all borrowings, payments, conversions, continuations,
Interest Periods, and notices in connection with Eurodollar Advances, any day
which is a Business Day described in clause (i) above which is also a day in
which dealings in Dollar deposits are carried out by the Applicable Lending
Office in the interbank eurodollar market where the eurodollar operations of
such Applicable Lending Office are customarily conducted.






                                       4
<PAGE>   10
         "Capital" means the sum of (i) Consolidated Funded Debt of Borrower
plus (ii) the Tangible Net Worth of Borrower, determined in accordance with
GAAP.

         "Capital Expenditure" means any payment made or obligation incurred by
Borrower or any of its Subsidiaries in respect of the purchase, capital lease
or other acquisition of assets other than current assets including any
expenditure that would be classified as a "capital expenditure" in accordance
with GAAP.  For purposes of this definition, a "Capital Expenditure" shall be
deemed to have occurred in an amount equal to the aggregate of all payments to
come due over the full term of a capital lease at the time that Borrower or any
of its Subsidiaries enters into such capital lease.

         "Capital Lease Obligation" means, at any time as to any Person with
respect to any Property leased by such Person as lessee, the amount of the
liability with respect to such lease that would be required at such time to be
capitalized and accounted for as a capital lease on the balance sheet of such
Person prepared in accordance with GAAP.

         "Cash Proceeds" means, with respect to any Asset Sale by any Person,
the aggregate consideration received for such Asset Sale by such Person in the
form of cash or cash equivalents (including any amounts of insurance or other
proceeds received in connection with an Asset Sale of the type described in the
last sentence of the definition thereof), including payments in respect of
deferred payment obligations when received in the form of cash or cash
equivalents (except to the extent that such obligations are financed or sold
with recourse to such Person or any subsidiary thereof).  For purposes of this
definition, "cash or cash equivalents" shall be deemed to include, for a period
not to exceed 12 months from the related Asset Sale, noncash consideration
received with respect to an Asset Sale to the extent that such noncash
consideration consists of publicly traded debt securities of a Person, which
securities are rated at least "BBB-" by S&P and at least "Baa3" by Moody's or
having a comparable rating from the successors of each of such rating agencies.

         "Change of Control" shall be deemed to have occurred at such time as
(i) a "person" or "group" within the meaning of Sections 13(d) or 14(d)(2) of
the Securities Exchange Act of 1934, as amended (the "1934 Act"), other than
the Borrower becomes the "beneficial owner" (as defined in Rule 13d-3 under the
1934 Act) of more than 20% of the Voting Stock of the Borrower, or (ii) a
person enters into an agreement with the Borrower to purchase, lease, or
otherwise acquire, all or substantially all of the assets of the Borrower or
(iii) during any period of two consecutive years (not including any period
prior to the execution of this Agreement), individuals who at the beginning of
such period constitute the Borrower's Board of Directors (and any new director,
whose election by the Borrower's stockholders was approved by a vote of at
least two-thirds of the directors then still in office who either were
directors at the beginning of the period or whose election or nomination for
election was so approved), cease for any reason to constitute a majority
thereof.

         "Code" means the Internal Revenue Code of 1986, as amended.

         "Collateral Account" shall have the meaning given to such term in
Section 6.02 hereof.





                                       5
<PAGE>   11
         "Commitment" means, with respect to each of the Banks, the obligation
of such Bank to make Loans to the Borrower and to participate in the issuance
of Letters of Credit under Article II hereof, up to the maximum amounts therein
stated.

         "Commitment Fee" shall have the meaning given to such term in Section
2.06 hereof.

         "Consolidated" shall mean, with reference to any item, such item of
the Borrower and its Subsidiaries, consolidated in accordance with GAAP.

         "Consolidated Cash Operating Income" means, for any period, total
operating income of Borrower and its Consolidated Subsidiaries for such period,
determined in accordance with GAAP, plus all noncash expenses for such period
for such Persons.

         "Consolidated Current Liabilities" of any Person means, as of any
date, the total liabilities (including tax and other proper accruals) of such
Person and its subsidiaries on a consolidated basis at such date which may
properly be classified as current liabilities in accordance with GAAP.

         "Consolidated EBITDA" means, without duplication, for the period of
four fiscal quarters ended immediately prior to the date of calculation of
Consolidated EBITDA, for the Borrower and the Borrower's Consolidated
Subsidiaries, the sum of the amount for such period of four fiscal quarters of
(i) Consolidated Net Income, plus (ii) depreciation and amortization and other
noncash expenses, including without limitation deferred tax expense, of the
Borrower and the Consolidated Subsidiaries on a consolidated basis, plus (iii)
Consolidated Interest Expense, minus (iv) any non-cash income included in
Consolidated Net Income.

         "Consolidated Fixed Charges" means, without duplication, as of the
date of calculation thereof, the amounts of (i) Consolidated Interest Expense
for the preceding four fiscal quarters, plus (ii) current scheduled maturities
of principal on Indebtedness (including the principal component of capitalized
leases) owed by the Borrower and its Consolidated Subsidiaries for the four
fiscal quarters immediately preceding the date of calculation of Consolidated
Fixed Charges, plus (iii) all dividends on Preferred Stock of Borrower which
dividends Borrower is obligated to pay (and an obligation to pay Preferred
Stock dividends shall be deemed to exist whether or not such dividends are
cumulative) by the terms of such Preferred Stock for the four fiscal quarters
immediately preceding the date of calculation of Consolidated Fixed Charges.

         "Consolidated Funded Debt" means Funded Debt of Borrower and its
Subsidiaries determined on a Consolidated basis.

         "Consolidated Interest Expense" means, for any period(s), for the
Borrower and its Consolidated Subsidiaries, the sum of all interest in respect
of Indebtedness accrued or capitalized during such period (whether or not
actually paid during such period).

         "Consolidated Net Income" means, for any period, all consolidated
gross revenues and other proper income credits of the Borrower and the
Consolidated Subsidiaries for such period, less all operating and non-operating
expenses and other proper income charges of the Borrower





                                       6
<PAGE>   12
and the Consolidated Subsidiaries (including interest charges and taxes on
income) for such period; provided however, there shall not be included in such
revenues (i) any income representing the excess of equity in any Subsidiary at
the date of acquisition over the investment in such Subsidiary, (ii) any equity
in the undistributed earnings of any Person which is not a Consolidated
Subsidiary, (iii) any earnings of any Subsidiary for any period prior to the
date such Subsidiary was acquired, (iv) any gains resulting from the write-up,
appraisal or revaluation of assets after December 31, 1993, (v) any amounts
received in respect of services not then yet performed, (vi) any gains or
losses on the sale or other disposition of investments or fixed or capital
assets, and any taxes on such excluded gains and any deductions or credits on
account of any such excluded losses, (vii) the proceeds of any life insurance
policy on the life of any officer, director or employee of Borrower or its
Affiliates, and (viii) any other gain which is classified as "extraordinary" in
accordance with GAAP.

         "Consolidated Net Tangible Assets" of any Person means, as of any
date, Consolidated Tangible Assets of such Person at such date, after deducting
therefrom (without duplication of deductions) all Consolidated Current
Liabilities of such Person at such date.

         "Consolidated Subsidiaries" means, when used in connection with the
Borrower or any of its Subsidiaries, any corporation or other Person the
accounts and financial information of which is at the time included in the
Consolidated financial statements of the Borrower or such Subsidiary prepared
in accordance with GAAP.

         "Consolidated Tangible Assets" of any Person means, as of any date,
the sum of the Property of such Person and its subsidiaries on a consolidated
basis at such date, after eliminating intercompany items, and after deducting
from such total, without duplication, (i) all Property that would be classified
as intangibles under GAAP (including, without limitation, goodwill,
organizational expenses, trademarks, trade names, copyrights, patents, licenses
and any rights in any thereof), and (ii) any prepaid expenses, deferred charges
and unamortized debt discount and expense, each such item determined in
accordance with GAAP.

         "Contingent Liabilities" means any and all guaranties,
indemnifications, endorsements, support letters, contingent agreements, make
whole agreements, investment or loan commitments, and other contingent
obligations in respect of, or any obligations to purchase or otherwise acquire,
Indebtedness or obligations of others.

         "Controlled Group" means all members of a controlled group of
corporations and all members of a controlled group of trades or businesses
(whether or not incorporated) under common control which, together with
Borrower, are treated as a single employer under Section 41(b) of the Code or
Section 4001 of ERISA.

         "Credit Maturity Date" means 12:00 noon Houston, Texas time on June 9,
1996, or such earlier date and time on which the obligation of Banks to make
Loans and provide Letters of Credit hereunder is terminated and all Obligations
are immediately due and payable by Borrower, or such later date as may result
from the extension of the Credit Maturity Date as set forth in Section 2.02
hereof, or as may be otherwise agreed in writing by Borrower and Banks.





                                       7
<PAGE>   13
         "Currency Hedge Obligations" means, at any time as to any Person, the
obligations of such Person at such time which were incurred in the ordinary
course of business pursuant to any foreign currency exchange agreement, option
or future contract or other similar agreement or arrangement designed to
protect against or manage such Person's or any of its subsidiaries' exposure to
fluctuations in foreign currency exchange rates.

         "Current Assets" of any Person means, as of any date, the total assets
of such Person and its subsidiaries on a consolidated basis at such date which
may properly be classified as current assets in accordance with GAAP.

         "Debt to Capital Ratio" means the ratio of Consolidated Funded Debt
(determined in accordance with GAAP), of the Borrower, to Capital.

         "Default Rate" means at any time a per annum rate of interest equal to
3% plus the Base Rate, but in no event to exceed the Maximum Rate.

         "Determining Lenders" means any combination of Banks having at least
66 2/3% of the aggregate principal amount of outstanding Advances and Letter of
Credit Liabilities hereunder or, if no Advances or Letters of Credit are
outstanding at the time of determination thereof, such term means any
combination of Banks having Specified Percentages equal to at least 66 2/3%.

         "Dollars" or "$" means lawful currency of the United States of America.

         "Eligible Accounts" means, as of any date the determination thereof is
to be made by Agent, without duplication, the sum of the accounts (as such term
is defined in the UCC) owed to Borrower or the Significant Subsidiaries (other
than Non-Recourse Subsidiaries) by Eligible Account Debtors which meet each of
the following requirements as of the time any determination thereof is to be
made: (i) such accounts arose from an enforceable order or contract, written or
oral, for the absolute sale or lease of inventory of Borrower or its
Consolidated Subsidiaries which has been shipped to an Eligible Account Debtor
and not returned, rejected, lost or damaged or for the rendering of services by
Borrower or its Consolidated Subsidiaries, which has been fully and
satisfactorily performed, each in the ordinary course of business of Borrower
or its Consolidated Subsidiaries; (ii) the amounts shown on the books of
Borrower or its Consolidated Subsidiaries at such time in respect of such
accounts are the actual amounts owed by the applicable Eligible Account Debtor
in respect of such account; (iii) the rights of Borrower or its Consolidated
Subsidiaries in and to such accounts and the proceeds thereof are not subject
to any prior assignment or any other lien, claim or encumbrance, or any set-off
or other encumbrance; (iv) such accounts are not evidenced by any promissory
note, trade acceptance, draft or other instruments; (v) such account shall be
due and payable not more than 90 days from the date of the invoice of same and
shall be billed within five days after the shipment of the goods or performance
of the services giving rise to such account have been made; provided however,
that accounts due and payable within 120 days from the date of invoice of same,
and promptly billed (in accordance with the foregoing) to The Shell Petroleum
Development Company of Nigeria Limited and payable in Dollars (not in Nigerian
Naira) shall constitute an Eligible Account for purposes of this clause (v);
(vi) such accounts comply with all applicable legal requirements, including,
where applicable, the Federal





                                       8
<PAGE>   14
Consumer Act (as the same may be amended or supplemented from time to time);
(vii) such account is not otherwise in default or dispute; (viii) such account
is not included in the borrowing base under, or as a basis for financing under,
another credit facility besides this Agreement; (ix) the sum of all accounts
owed to Borrower or its Consolidated Subsidiaries by the same Eligible Account
Debtor does not exceed 15% of the total Eligible Accounts, and if such excess
exists, then the amount of such excess shall not constitute an Eligible
Account, (x) such account is owed in Dollars, except for accounts owed in
British Pounds Sterling or Canadian Dollars; (xi) if such accounts are owed to
a Significant Subsidiary, such Significant Subsidiary has either (a) executed
the Guaranty or (b) in the case of Foreign Subsidiaries which are Significant
Subsidiaries, executed an Intercompany Revolving Credit Note which has been
delivered to the Agent and pledged thereto pursuant to the Security Agreement,
and (xii) such accounts shall be, in the reasonable business judgment of the
Agent, otherwise acceptable to the Agent.

         "Eligible Account Debtor" means, as of any time the determination
thereof is to be made by the Agent, a Person that meets all of the following
requirements: (i) said Person is not an Affiliate of the Borrower or its
Consolidated Subsidiaries; (ii) none of the following events shall have
occurred with respect to said Person: a proceeding shall have been filed
seeking dissolution, termination of existence, insolvency, business failure or
appointment of a receiver for all or any part of the property of, or assignment
for the benefit of creditors by, said Person, or the filing of a petition in
bankruptcy or the commencement of any proceeding under any bankruptcy or
insolvency laws by or against said Person; (iii) no more than 25% of the total
amount, expressed in the currency in which such account is payable, of said
Person's open account indebtedness to the Borrower and its Affiliates taken as
a whole, arises pursuant to an invoice or invoices of the Borrower or any of
its Affiliates, is otherwise more than 90 days past due; except that in the
case of accounts for which The Shell Petroleum Development Company of Nigeria
Limited is the account debtor and owes its obligation in Dollars, no more than
25% of the total Dollar amount of such Person's open account indebtedness is
more that 150 days past due; (iv) said Person does business in or has a
substantial investment in assets located in the United States of America,
except for (A) account debtors who would satisfy such criteria with respect to
Canada or the United Kingdom, or (B) account debtors, for whom services were
rendered or to which goods were sold outside of the United States, Canada or
the United Kingdom, which on their own or by way of an Affiliate maintain a
senior debt credit rating by S&P of BBB- or better or (C) state owned oil
companies; (v) said Person is not a domestic, federal, state, provincial,
county, city or municipal government or political subdivision, and (vi) said
Person shall be, in the reasonable business judgment of the Agent, otherwise
acceptable to the Agent.

         "Eligible Assignee" means any financial institution, commercial bank
or U.S. agency or affiliate of any bank.

         "Environmental Laws" means any and all laws, statutes, ordinances,
rules, regulations, orders, requirements or determinations of any Governmental
Authority pertaining to health or the environment in effect in any and all
jurisdictions in which any of the Borrower or any of its Subsidiaries is
conducting or at any time has conducted business, or where any Property of any





                                       9
<PAGE>   15
of the Borrower or its Subsidiaries is located or where any hazardous
substances generated by or disposed of by any of Borrower of any of its
Subsidiaries are located.

         "ERISA" means the Employee Retirement Income Security Act of 1974, as
amended, together with regulations thereunder, and any successor statute of
similar import.

         "ERISA Affiliate" means any Person that for purposes of Title IV of
ERISA is a member of a Controlled Group of Borrower, within the meaning of
Section 414(c) of the Code and the regulations and rulings thereunder.

         "ERISA Event" means (a) a reportable event, within the meaning of
Section 4043 of ERISA, unless the 30-day notice requirement with respect
thereto has been waived by the PBGC, (b) the issuance by the administrator of
any Plan of a notice of intent to terminate such Plan, pursuant to Section
4041(a)(2) of ERISA (including any such notice with respect to a plan amendment
referred to in Section 4041(e) of ERISA), (c) the cessation of operations at a
facility in the circumstances described in Section 4068(f) of ERISA, (d) the
withdrawal by Borrower, any Subsidiary of Borrower, or any ERISA Affiliate from
a Multiple Employer Plan during a Plan year for which it was a substantial
employer, as defined in Section 400(a)(2) of ERISA, (e) the failure by
Borrower, any Subsidiary of Borrower, or any ERISA Affiliate to make a payment
to a plan required under Section 302 of ERISA, (f) the adoption of an amendment
to a plan requiring the provision of security to such plan, pursuant to Section
307 of ERISA, or (g) the institution by the PBGC of proceedings to terminate a
plan, pursuant to Section 4042 of ERISA, or the occurrence of any event or
condition that constitutes grounds under Section 4042 of ERISA for the
termination of, or the appointment of a trustee to administer, a plan.

         "Eurodollar Advance" means any Advance that bears interest at a rate
based upon the Adjusted Eurodollar Rate.

         "Eurodollar Rate" shall mean, with respect to any Interest Period or
portion thereof, the rate per annum (rounded upwards, if necessary, to the
nearest 1/16th of 1%) shown on page 3750 of the Dow Jones & Company Telerate
screen or any successor page as the composite offered rate for London interbank
deposits with a period equal to such Interest Period (or portion thereof), as
shown under the heading "USD" as of 11:00 a.m. (London time) two Business Days
prior to the first day of such Interest Period; provided that if no such rate
appears, the rate shall be the rate per annum based on the rates at which
Dollar deposits with a period equal to such Interest Period (or portion
thereof) are displayed on page "LIBO" of the Reuters Monitor Money Rates
Service or such other page as may replace the LIBO page on that service for the
purpose of displaying London interbank offered rates of major banks as of 11:00
a.m. (London time) two Business Days prior to the first day of such Interest
Period; it being understood that if at least two such rates appear on such
page, the rate will be the arithmetic mean of such displayed rates; provided
that if fewer than two such rates are displayed, the rate shall be the rate per
annum equal to the average of the rates at which deposits in dollars are
offered to the Agent at approximately 11:00 a.m. (London time) two Business
Days prior to the first day of such Interest Period to prime banks in the
London interbank market in an amount approximately equal to the amount of the
Eurodollar Advance with a period equal to such Interest Period (or portion
thereof); it being understood that if at least two such quotations are
provided, the rate shall be





                                       10
<PAGE>   16
the arithmetic mean of such provided rates; and provided further that if fewer
than two such rates are provided, the rate shall be the arithmetic mean of the
rates quoted by major banks in New York City, selected by the Agent, at
approximately 11:00 a.m. (New York City time) on the first day of such Interest
Period to leading European banks in an amount approximately equal to the amount
of the Eurodollar Advance with a period equal to such Interest Period (or
portion thereof).

         "Event of Default" means any of the events specified in Section 6.01
hereof which has occurred and is continuing, provided that there has been
satisfied any requirement in connection with such event for the giving of
notice, or the lapse of time, or the happening of any further condition, event
or act, and "Default" shall mean any of such events, whether or not any such
requirement has been satisfied.

         "Excess Cash on Hand" means, at any date of determination of Special
Purpose Fixed Charges, the excess, if any (and such excess shall be deemed to
be zero if it would otherwise be a negative number), obtained by subtracting
(i) $25,000,000 from (ii) the sum, based on the most recent Consolidated
balance sheet of Borrower and its Subsidiaries delivered pursuant to Section
4.01 hereof, of (A) cash and (B) cash equivalents determined in accordance with
GAAP, and (C) Permitted Investments in marketable securities determined in
accordance with GAAP, provided that amounts included under the foregoing
clauses (A), (B) or (C) must be subject to withdrawal, sale or liquidation, as
applicable, without penalty, limitation or restriction.

         "Excess Proceeds" means that amount of Net Available Proceeds not
applied to the acquisition of Replacement Assets.

         "Facility Fee" means the fee payable by the Borrower to First
Interstate as described in Section 2.06(c) hereof.

         "Fair Market Value" means, with respect to the total consideration
received pursuant to any Asset Sale or by any Person as contemplated by Section
5.18 hereof or any noncash consideration received by any Person, the fair
market value of such consideration as determined in good faith by the board of
directors of the Borrower.

         "Fair Value" means, with respect to any asset or Property, the price
which could be negotiated in an arms-length free market transaction, for cash,
between a willing seller and a willing buying, neither of whom is under undue
pressure or compulsion to complete the transaction.

         "Federal Funds Rate" means for any period, a fluctuating interest rate
"per annum" equal for each day during such period to the weighted average of
the rates on overnight federal funds transactions with members of the Federal
Reserve System arranged by federal funds brokers, as published for such day
(or, if such day is not a Business Day, for the next preceding Business Day) by
the Federal Reserve Bank of New York, or, if such rate is not so published for
any day which is a Business Day, the average of the quotations for such day on
such transactions received by the Agent from three federal funds brokers of
recognized standing selected by it.





                                       11
<PAGE>   17
         "Financial Statements" means the copies delivered to the Agent of the
consolidated balance sheets of the Borrower as of December 31, 1993, and March
31, 1994, and the related consolidated statement of income and retained
earnings and cash flows of the Borrower for the period stated therein.

         "First Interstate" means First Interstate Bank of Texas, N.A. in its
individual capacity, and its successors and assigns.

         "Fixed Charge Coverage Ratio" means, as of the last day of any fiscal
quarter of the Borrower, the ratio of (i) Consolidated EBITDA of the Borrower
to (ii) Consolidated Fixed Charges of the Borrower.

         "Foreign Subsidiary" means a Subsidiary of the Borrower incorporated
under the laws of any jurisdiction other than the United States of America, any
state thereof or the District of Columbia.

         "Funded Debt" means for any Person (without duplication):  (i) all
indebtedness for the repayment of borrowed money, whether or nor represented by
bonds, debentures, notes, securities, bankers' acceptances or other evidences
of indebtedness, regardless of whether such indebtedness would be classified in
accordance with GAAP as a current liability or long-term debt, and (ii) all
reimbursement and repayment obligations then due in respect of a drawing of a
letter of credit, or guaranty, surety, indemnity, reimbursement or other
similar obligations then due.

         "GAAP" means United States generally accepted accounting principles,
applied on a consistent basis, as set forth in Opinions of the Accounting
Principles Board of the American Institute of Certified Public Accountants or
in statements of the Financial Accounting Standards Board or their successors
which are applicable in the circumstances as of the date of determination of
any item; and the requirement that such principles be applied on a "consistent
basis" shall mean that the accounting principles observed in a current period
be comparable in all material respects to those applied in a preceding period.

         "Governmental Authority" means any domestic or foreign federal, state,
province, county, city, municipality or political subdivision in which any of
the Borrower or any of its Subsidiaries, is located or which exercises
jurisdiction over any Property of the Borrower or any of its Subsidiaries, and
any agency, department, commission, board, tribunal, court, bureau or
instrumentality of any of them which exercises or has jurisdiction over any
such Property.

         "Governmental Requirement" means (without duplication) any law,
statute, code, ordinance, order, rule, regulation, judgment, decree,
injunction, franchise, permit, certificate, license, authorization or other
directive or requirement (including, without limitation, Environmental Laws,
energy regulations and occupational, safety and health standards or controls)
of any Governmental Authority.





                                       12
<PAGE>   18
         "Grasso Agreement" means the Exchange Agreement dated as of June 4,
1993, by and among the Borrower, Offshore Logistics, Inc., Grasso Corporation,
PP1-Seahawk Services, Inc. and Noble Production Services, Inc.

         "Guaranty" means that certain guaranty agreement entered into, dated,
executed and delivered by each of the Significant Subsidiaries other than (i)
Triton and (ii) a Foreign Subsidiary as of the date of this Agreement, in
substantially the form of Exhibit D attached hereto, and all guaranties in
substantially similar form executed subsequent to the date hereof pursuant to
Section 4.11.

         "Hazardous Materials" means all materials subject to any Environmental
Law, including without limitation materials listed in 49 CFR Section 172.101,
Hazardous Substances, explosive or radioactive materials, hazardous or toxic
wastes or substances, petroleum or petroleum distillates, asbestos, or material
containing asbestos.

         "Hazardous Substances" means "hazardous waste" as defined in the Clean
Water Act, as amended, 33 U.S.C. Section 1251 et seq., the Comprehensive
Environmental Response Compensation and Liability Act, as amended (including
the Superfund Amendments and Reauthorization Act), 41 U.S.C. Section 9601 et
seq., the Resource Conservation Recovery Act, 42 U.S.C. Section 6901 et seq.,
as amended, and the Toxic Substances Control Act, as amended, 15 U.S.C. Section
2601 et seq.

         "Indebtedness" means and includes, without duplication, (1) all items
which in accordance with GAAP, consistently applied, would be included on the
liability side of a balance sheet on the date as of which Indebtedness is to be
determined (excluding capital stock, surplus and surplus reserves, retained
earnings, minority interests and deferred liabilities), including, without
limiting the generality of the foregoing and without duplication, Funded Debt,
(2) Contingent Liabilities, and (3) indebtedness secured by any mortgage,
pledge, security interest or lien existing on any interest of the Person with
respect to which Indebtedness is being determined in property owned subject to
such mortgage, pledge, security interest or lien whether or not the
indebtedness secured thereby shall have been assumed.

         "Insolvent" means, with respect to any Person, that (i) the fair
saleable value of the assets of such Person does not exceed the amount that
would be required to be paid on or in respect to the existing debts and other
liabilities (including, without limitation, pending or overtly threatened
litigation in amounts in excess of effective insurance coverage and all other
contingent liabilities) of such Person as they mature, or (ii) the assets of
such Person constitute unreasonably small capital for such Person to carry out
its business as then being conducted or as proposed to be conducted including
the capital needs of such Person, taking into account the particular capital
requirements of the business conducted by such Person and projected capital
requirements and capital availability thereof, or (iii) the fair saleable value
of the assets of such Person is not greater than the total fair value of the
liabilities, including contingent, subordinated, absolute, fixed, or matured or
unmatured liabilities of such Person.

         "Intercompany Revolving Credit Note" means a revolving credit
promissory note, made by a Significant Subsidiary that is a Foreign Subsidiary
(other than Noble Drilling (Canada)





                                       13
<PAGE>   19
Ltd.) to the order of Borrower in the original principal amount of $20,000,000
or such lesser amount as is actually outstanding thereunder, evidencing loans
made or to be made by Borrower to such Subsidiary, in the form attached hereto
as Exhibit E.

         "Interest Payment Date" means (i) with respect to each of the Base
Rate Advances, the last Business Day of each March, June, September and
December, and (ii) with respect to each Eurodollar Advance, the last day of the
Interest Period applicable thereto.

         "Interest Period" means with respect to any Eurodollar Advance, the
period commencing on the date, as applicable, such Advance is made or converted
from an Advance of another Type or, in the case of each subsequent, successive
Interest Period applicable to a Eurodollar Advance, the last day of the next
preceding Interest Period with respect to such Advance, and ending on the
numerically corresponding day in the first, second or third calendar month
thereafter, as Borrower may select as provided in Section 2.03 hereof, except
that each such Interest Period which commences on the last Business Day of a
calendar month (or on any day for which there is no numerically corresponding
day in the appropriate subsequent calendar month) shall end on the last
Business Day of the appropriate subsequent calendar month.

         Notwithstanding the foregoing:

                 (a)      each Interest Period which would otherwise end on a
         day which is not a Business Day shall end on the next succeeding
         Business Day, except that if such succeeding Business Day falls in the
         next succeeding calendar month, than such Interest Period shall end on
         the next preceding Business Day;

                 (b)      no Interest Period for any Eurodollar Advance shall
         have a duration of less than one month, and if the Interest Period for
         any Eurodollar Advance would otherwise be a shorter period, such
         Advance shall not be available hereunder; and

                 (c)      no Interest Period may extend beyond the maturity of
         the Note or the Credit Maturity Date.

         "Interest Swap Obligations" means, with respect to any Person, the
obligations of such Person pursuant to any interest rate swap agreement,
interest rate cap, collar or floor agreement or other similar agreement or
arrangement designed to protect against or manage such Person's or any of its
subsidiaries' exposure to fluctuations in interest rates.

         "Investment" means any direct or indirect loan, advance, guaranty or
other extension of credit or capital contribution to (by means of transfers of
cash or other property to others or payments for Property or services for the
account or use of others, or otherwise), or purchase or acquisition of capital
stock, bonds, notes, debentures or other securities or evidences of
Indebtedness issued by, any other Person.  The amount of any Investment shall
be the original cost of such Investment, plus the cost of all additions
thereto, and minus the amount of any portion of such Investment repaid to such
person in cash as a repayment of principal or a return of capital, as the case
may be, but without any other adjustments for increases or decreases in value,
or write-ups, write-downs or write-offs with respect to such investment.  In
determining





                                       14
<PAGE>   20
the amount of any Investment involving a transfer of any Property other than
cash, such Property shall be valued at Fair Value at the time of such transfer
as determined in good faith by the board of directors (or comparable body) of
the Person making such transfer.

         "Law" means any constitution, statute, law, ordinance, regulation,
rule, order, writ, injunction or decree of any Tribunal.

         "Letter of Credit" means a letter of credit (as defined in the UCC)
issued by First Interstate at the request of the Borrower, naming a beneficiary
(as defined in the UCC) designated by the Borrower, all in accordance with the
provisions of Sections 2.08 and 2.09 hereof.

         "Letter of Credit Liabilities" means, at any time and in respect of
any Letter of Credit, the sum of (a) the undrawn face amount of such Letter of
Credit plus (b) the aggregate unpaid amount of all Reimbursement Obligations at
the time due and payable in respect of drawings made under such Letter of
Credit.

         "L/C Facility" means the credit facility provided by the Banks to the
Borrower, for the benefit of the Borrower and its Subsidiaries for the issuance
of Letters of Credit, all in accordance with Sections 2.08 and 2.09 hereof.

         "Lien" means any interest in Property securing an obligation owed to,
or a claim by, a Person other than the owner of the Property, whether such
interest is based on the common law, statute or contract, and whether such
obligation or claim is fixed or contingent, and including but not limited to a
lien, security interest or other interest arising from a mortgage, deed of
trust, assignment, encumbrance, pledge, security agreement, conditional sale,
trust receipt, lease, consignment, bailment for security purposes, or
conditional sale agreement, lease purchase agreement, sale and leaseback
arrangement or other similar title retention agreement.

         "Litigation" means any proceeding, claim, lawsuit, and/or
investigation conducted by or before any Tribunal.

         "Loan" means an extension of credit or financial accommodation by way
of a loan or Advance hereunder to the Borrower.

         "Loan Documents" means this Agreement, the Note, the Loan Formula
Certificates, the Guaranty, the Assignments and Acceptances, if any, the
Letters of Credit, the Applications, the Security Agreement, and all other
promissory notes, drafts, security agreements, reports, opinions, requests for
Advances, certificates and other instruments, documents, and agreements now or
hereafter executed and delivered pursuant to, or in connection with, this
Agreement.

         "Loan Formula Certificate" means a duly certified report, in form and
substance substantially similar to that which is attached hereto as Exhibit F,
with the blanks therein properly and accurately completed, and setting forth
the limitations on total Loans and the limitations on Letters of Credit in
Article II hereof, such certificate being executed by an Authorized
Representative of Borrower.





                                       15
<PAGE>   21
         "Loan Request Form" means a certificate, in substantially the form of
Exhibit G hereto, properly completed and signed by the Borrower requesting an
Advance attached to which is a Loan Formula Certificate.

         "Material Adverse Effect" means, with respect to any Person, a
material and adverse effect on (i) the business, financial condition or results
of operations of such Person, or (ii) its ability to fulfill, punctually and
completely, its obligations under each Loan Document.

         "Maximum Rate" means the maximum lawful nonusurious rate of interest
(if any) which under Applicable Law the Banks may charge the Borrower on the
Loans from time to time.  If, however, during any period interest accruing on
any Loan is not limited to any maximum lawful non-usurious rate of interest
under Applicable Law, then during each such period the "Maximum Rate" shall be
equal to a per annum rate of 3% plus the Base Rate from time to time in effect.

         "Moody's" means Moody's Investors Service, Inc. and its successors.

         "Multiemployer Plan" means a "multiemployer plan" as defined in
Section 4001(a)(3) of ERISA to which Borrower, any Subsidiary thereof, or any
ERISA Affiliate is making or accruing an obligation to make contributions, or
has within any of the preceding five plan years made or accrued an obligation
to make contributions, such plan being maintained pursuant to one or more
collective bargaining agreements.

         "Multiple Employer Plan" means a single employer plan, as defined in
Section 4001(a)(15) of ERISA, that (a) is maintained for employees of Borrower,
any Subsidiary of Borrower, or any ERISA Affiliate and at least one Person
other than Borrower, any Subsidiary of Borrower and any ERISA Affiliate, or (b)
was so maintained and in respect of which Borrower, any Subsidiary of Borrower,
or any ERISA Affiliate could have liability under Section 4064 or 4069 of ERISA
in the event such plan has been or were to be terminated.

         "Net Available Proceeds" means, as to any Asset Sale, the Cash
Proceeds therefrom (i) minus, without duplication, the sum of (A) reasonable
legal and title expenses, commissions and other reasonable fees and expenses
incurred, and all Federal, state, provincial, foreign, recording and local
taxes payable as a consequence of such Asset Sale, and (B) all payments to any
Person other than the Borrower or a Subsidiary on any Indebtedness of the
Company or its Subsidiaries which is secured by such assets, in accordance with
the terms of any Lien upon or with respect to such assets, or which must by its
terms, or in order to obtain a necessary consent to such Asset Sale, or by
applicable law, be repaid out of the proceeds from such Asset Sale, and (ii) in
the case of an Asset Sale by a Subsidiary, multiplied by the percentage of the
Voting Stock of such Subsidiary directly or indirectly owned by the Borrower.

         "NN-1 Rig Facility" means the outstanding United States Government
Ship Financing Bonds, Noble - National 1978 Series of NN-1 Limited Partnership
(as successor to Noble - National Joint Venture) issued September 13, 1978.

         "Non-Recourse Indebtedness" means any Indebtedness of a Non-Recourse
Subsidiary (a) in respect to which neither the Borrower nor any of its
Subsidiaries (other than a Non-Recourse





                                       16
<PAGE>   22
Subsidiary) is liable or obligated in any manner including, without limitation,
liabilities or obligations constituting Indebtedness of the Borrower or any of
its Subsidiaries (other than a Non-Recourse Subsidiary), and (b) the occurrence
of any event or existence of any condition under any agreement or instrument
relating to which shall not at any time have the effect of accelerating, or
permitting the acceleration of, the maturity of any Indebtedness of the
Borrower or of its Subsidiaries (other than a Non-Recourse Subsidiary) or
otherwise permitted any such Indebtedness to be declared to be due and payable,
or to be required to be prepaid, purchased or redeemed, prior to the stated
maturity thereof.

         "Non-Recourse Subsidiary" means a Subsidiary that (a) owns only
Property acquired by such Subsidiary after October 7, 1993 and (b) has no
Indebtedness other than Non-Recourse Indebtedness.

         "Notes" mean each Revolving Note made to the order of one of the Banks.

         "Obligations" means all obligations, indebtedness, accrued unpaid
interest, Letter of Credit Liabilities, fees, expenses, costs, indemnities and
liabilities of Borrower to Banks, including without limitation all Loans, now
existing or hereafter arising, whether direct, indirect, related, unrelated,
fixed, contingent, liquidated, unliquidated, joint, several, or joint and
several, under, or in connection with, this Agreement and the other Loan
Documents.

         "Operating Loss Increment" means, for each Quarterly Reporting Period,
if two consecutive Quarterly Operating Losses have occurred in the 12 month
period that includes such Quarterly Reporting Period ("Combined Operating
Losses"), then effective as of the first day after such Quarterly Reporting
Period and effective for the next succeeding twelve-month period, an amount
equal to .50% per annum; provided, that if additional Quarterly Operating
Losses occur in any 12 month period after Combined Operating Losses have
occurred, the Operating Loss Increment shall not at any time exceed in
aggregate .50% per annum.

         "Payment Office" shall mean the Agent's office located at 1000
Louisiana, 3rd Floor, Houston, Texas 77002, or the office of the duly appointed
successor to the Agent, as indicated in writing by such successor, to the
Borrower and the Banks.

         "PBGC" means the Pension Benefit Guaranty Corporation and any entity
succeeding to any or all of its functions under ERISA.

         "Pension Plan" means a "pension plan", as such term is defined in
Section 3(2) of ERISA, which is subject to Title IV of ERISA (other than a
multiemployer plan as defined in Section 4001(a)(3) of ERISA), and to which the
Borrower or any corporation, trade or business that is, along with the
Borrower, a member of a Controlled Group, may have liability, including any
liability by reason of having been a substantial employer within the meaning of
Section 4063 of ERISA at any time during the preceding five years, or by reason
of being deemed to be a contributing sponsor under Section 4069 of ERISA.

         "Permitted Subsidiary Indebtedness" means:





                                       17
<PAGE>   23
                 (i)      Indebtedness of the Borrower or any Subsidiary under
         Interest Swap Obligations; provided that (a) such Interest Swap
         Obligations are related to payment obligations on Indebtedness
         otherwise permitted by Section 5.01, and (b) the notional principal
         amount of such Interest Swap Obligations does not exceed the principal
         amount of the Indebtedness to which such Interest Swap Obligations
         relate;

                 (ii)     Indebtedness of the Borrower or any Subsidiary under
         Currency Hedge Obligations; provided that (a) such Currency Hedge
         Obligations are related to payment obligations on Indebtedness
         otherwise permitted by Section 5.01 or to the foreign currency cash
         flows reasonably expected to be generated by the Borrower and the
         Subsidiaries, and (b) the notional principal amount of such Currency
         Hedge Obligations does not exceed the principal amount of the
         Indebtedness or the amount of the foreign currency cash flows to which
         such Currency Hedge Obligations relate;

                 (iii)    Indebtedness of the Borrower or any Subsidiary
         outstanding on June 16, 1994 and listed on Schedule 3.10;

                 (iv)     Indebtedness of the Borrower or any Subsidiary in
         respect of performance bonds, surety bonds, appeal bonds and letters
         of credit issued for the account of the Borrower or any Subsidiary, in
         each case in the ordinary course of business;

                 (v)      Indebtedness of any Subsidiary to the Borrower or any
         Wholly-Owned Subsidiary (but only so long as it remains a Wholly-Owned
         Subsidiary);

                 (vi)     Non-Recourse Indebtedness of any Non-Recourse
         Subsidiary;

                 (vii)    other Indebtedness of the Borrower or any Subsidiary;
         provided that at the date such Indebtedness is incurred and after
         giving effect to the incurrence of such Indebtedness, the aggregate
         amount of all Indebtedness outstanding at such time under this clause
         (vii) shall not exceed $20,000,000; provided further that at the date
         any Indebtedness of a Subsidiary is incurred and after giving effect
         to the incurrence of such Indebtedness, (a) the outstanding secured
         Indebtedness of the Borrower (other than Indebtedness secured by Liens
         described under clauses (ix) and (xvii) of the definition of
         "Permitted Liens"), (b) all Indebtedness and the aggregate liquidation
         value of all Preferred Stock of any Subsidiary (other than a
         Non-Recourse Subsidiary) incurred and outstanding in accordance with
         Section 5.15 (other than of the type described in clauses (ix), (xiv)
         and (xvii) of the definition of "Permitted Liens"), and (c) the
         aggregate amount of all Capital Lease Obligations of the Borrower and
         its Subsidiaries, does not exceed 10% of the Borrower's Consolidated
         Net Tangible Assets;

                 (viii)   Permitted Refinancing Indebtedness; and

                 (ix)     Indebtedness of the Borrower's Subsidiaries arising
         under this Agreement in favor of the Banks.





                                       18
<PAGE>   24
So as to avoid duplication in determining the amount of Permitted Subsidiary
Indebtedness under any clause of this definition, guarantees of, or obligations
in respect of letters of credit supporting, Indebtedness otherwise included in
the determination of such amount shall not also be included.

         "Permitted Investments" means:

                 (i)      certificates of deposit, bankers' acceptances, time
         deposits, eurocurrency deposits and similar types of investments
         routinely offered by commercial banks with final maturities of one
         year or less issued by commercial banks having capital and surplus in
         excess of $100,000,000;

                 (ii)     commercial paper issued by any corporation, if such
         commercial paper has credit ratings of at least A-1 by S&P or at least
         P-1 by Moody's;

                 (iii)    U. S. Government Obligations with a maturity of four
         years or less;

                 (iv)     repurchase obligations for instruments of the type
         described in clause (iii) hereof; 

                 (v)      shares of money market mutual or similar funds 
         having assets in excess of $100,000,000;

                 (vi)     payroll advances in the ordinary course of business;

                 (vii)    other advances and loans to officers and employees of
         the Borrower or any Subsidiary, so long as the aggregate principal
         amount of such advances and loans does not exceed $500,000 at any one
         time outstanding;

                 (viii)   Investments in Replacement Assets;

                 (ix)     loans to or investments in (a) any Subsidiary (other
         than a Non-Recourse Subsidiary) by any other Subsidiary or by
         Borrower, other than loans to or investments in Subsidiaries
         constituting partnerships or joint ventures, or (b) Borrower by any
         Subsidiary; and

                 (x)      Investments in any partnerships or joint ventures,
         provided that the aggregate Investment in all such partnerships and
         joint ventures by the Borrower and its Subsidiaries, taken as a whole,
         does not at any time exceed 10% of Tangible Net Worth.

         "Permitted Liens" means:

                 (i)      Liens for taxes, assessments and other governmental
         charges or levies or liens arising under the General Maritime Law of
         the United States such as arise from necessaries provided by
         contractors or subcontractors, towage,





                                       19
<PAGE>   25
         general average or salvage, or the claims or demands of landlords,
         carriers, warehousemen, mechanics, laborers, materialmen and other
         like Persons, all of the foregoing arising by operation of law in the
         ordinary course of business for sums which are not yet due and
         payable, or such Liens the enforcement of which are, at all times,
         effectively and fully stayed and are being contested in good faith by
         appropriate proceedings diligently conducted, and for which reserves
         as required under generally accepted accounting principles shall have
         been established;

                 (ii)     deposits or pledges to secure the payment of
         workmen's compensation, unemployment insurance or other social security
         benefits or obligations, public or statutory obligations, surety or
         appeal bonds or other obligations of a like general nature incurred in
         the ordinary course of business;

                 (iii)    zoning restrictions, easements, licenses,
         restrictions on the use of real property or minor irregularities in
         title thereto which do not materially impair the use of such property
         in the operation of the business of the Borrower, or the Significant
         Subsidiaries or the value of such property;

                 (iv)     inchoate liens arising under ERISA to secure current
         service pension liabilities as they are incurred under the provisions
         of Plans from time to time in effect;

                 (v)      rights reserved to or vested in any municipality or
         governmental, statutory or public authority to control or regulate any
         property of the Borrower or the Significant Subsidiaries, or to use
         such property in a manner which does not materially impair the use of
         such property for the purposes for which it is held by the Borrower or
         the Significant Subsidiaries;

                 (vi)     Liens on Property of the Borrower or its Subsidiaries
         as set forth on Schedule 1 attached hereto;

                 (vii)    Liens on Property of a Person, other than Liens on
         Current Assets of such Person, existing at the time such Person has
         merged or consolidated with or into the Borrower or any Subsidiary
         thereof (and not incurred at a result of, or in anticipation of, such
         transaction); provided, that such Lien relates solely to the Property
         subject thereto;

                 (viii)   Liens on Property, other than Liens on Current
         Assets, existing at the time of the acquisition thereof (and not
         incurred as a result of, or in anticipation of, such transaction);
         provided, that such Lien relates solely to the Property subject
         thereto;

                 (ix)     Liens, other than Liens on Current Assets, to secure
         the payment of all or a part of the purchase price or construction
         costs of Property acquired or constructed after June 16, 1994;
         provided, that (a) the principal amount of





                                       20
<PAGE>   26
         Indebtedness secured by such Liens shall not exceed (i) 66 2/3%
         multiplied by (ii) the lesser of the cost or Fair Market Value of the
         Property so acquired or constructed; and (b) such Liens shall not
         encumber any other assets or Property of the Borrower or any
         Subsidiary thereof and shall attach to such Property within 90 days of
         the construction or acquisition of such Property;

                 (x)      Liens, other than Liens on Current Assets, in favor
         of the Lessor on Property subject to Capital Lease Obligations;
         provided, that such Liens secure Capital Lease Obligations which, when
         combined with (a) the outstanding secured Indebtedness of the Borrower
         (other than Indebtedness secured by Liens described in clauses (ix)
         and (xvii) of this definition), and (b) all Indebtedness of Borrower
         and its Consolidated Subsidiaries plus the aggregate liquidation value
         of all preferred stock of any Subsidiary (other than a Non-Recourse
         Subsidiary) incurred and outstanding in accordance with Section 5.15
         (other than of the type described in clauses (ix), (xiv) and (xvii)
         hereof), and (c) the aggregate amount of all Capital Lease Obligations
         of the Borrower and its Subsidiaries, does not exceed 10% of the
         Borrower's Consolidated Net Tangible Assets;

                 (xi)     Liens, other than Liens on Current Assets, securing
         Project Finance Indebtedness of the Borrower or any Subsidiary
         thereof; provided, that (a) the principal amount of Indebtedness
         secured by such Liens shall not exceed (i) 50% multiplied by (ii) the
         aggregate amount of capital expenditures to be made that directly
         relate to the repair, refurbishment, upgrade or improvement of the
         relevant asset or Property; (b) such Liens shall not encumber any
         other asset or Property of the Borrower or any Subsidiary thereof; (c)
         such Liens secure Project Finance Indebtedness which, when combined
         with (i) the outstanding secured Indebtedness of the Borrower (other
         than Indebtedness secured by Liens described under clauses (ix) and
         (xvii) hereof), (ii) all Indebtedness and the aggregate liquidation
         value of all preferred stock of any Subsidiary (other than a
         Non-Recourse Subsidiary) incurred and outstanding in accordance with
         Section 5.15 (other than of the type described in clauses (ix), (xiv)
         and (xvii) hereof), and (iii) the aggregate amount of all Capital
         Lease Obligations of the Borrower and its Subsidiaries, does not
         exceed 10% of the Borrower's Consolidated Net Tangible Assets; and (d)
         after giving effect to the occurrence of such Project Finance
         Indebtedness and any Lien created thereby, the ratio of (i) the Fair
         Value (as determined by a nationally recognized independent appraiser
         of drilling rigs) of the drilling rigs of the Borrower and its
         Consolidated Subsidiaries that are not subject to any Lien, to (ii)
         the aggregate amount of unsecured Indebtedness of the Borrower
         outstanding at such time and determined on a consolidated basis
         (including, without limitation, the Indebtedness under this
         Agreement), equals or exceeds 2.0 to 1.0;

                 (xii)    Liens securing Indebtedness of the Borrower or any
         Subsidiaries; provided, that such Liens secure Indebtedness which,
         when combined with (a) the outstanding secured Indebtedness of the
         Borrower and its Consolidated Subsidiaries (other than Indebtedness
         secured by Liens described in clauses (ix)





                                       21
<PAGE>   27
         and (xvii) hereof), (b) all Indebtedness plus the aggregate
         liquidation value of all Preferred Stock of any Subsidiary (other than
         a Non-Recourse Subsidiary) incurred and outstanding in accordance with
         Section 5.15 (other than of the type described in clauses (ix), (xiv)
         and (xvii) hereof, and (c) the aggregate amount of all Capital Lease
         Obligations of the Borrower and its Subsidiaries, does not exceed 10%
         of the Borrower's Consolidated Net Tangible Assets; provided further
         however, that no Liens otherwise permitted under this clause (xii)
         shall cover any Current Assets of Borrower or any of its Subsidiaries,
         except for Liens disclosed on Schedule 1 hereto, and Liens covering
         Current Assets of Triton which Current Assets secure working capital
         lines of credit of Triton.

                 (xiii)   Liens to secure any extension, renewal, refinancing
         or refunding (or successive extensions, renewals, refinancings or
         refundings), in whole or in part, of any Indebtedness secured by Liens
         referred to in clauses (vi), (vii) and (viii) of this definition;
         provided, that such Lien does not extend to any other Property of the
         Borrower or any Subsidiary thereof and the principal amount of the 
         Indebtedness secured by such Lien has not increased;

                 (xiv)    Liens granted by a Non-Recourse Subsidiary securing
         Non-Recourse Indebtedness of such Non-Recourse Subsidiary and Liens on
         the capital stock of a Non-Recourse Subsidiary securing Non-Recourse
         Indebtedness of such Non-Recourse Subsidiary;

                 (xv)     any charter or lease that would not constitute an
         Asset Sale pursuant to clause (D) of the definition of "Asset Sale";

                 (xvi)    leases or subleases of real property to other 
         Persons; and

                 (xvii)   Liens required under this Agreement in favor of the
         Banks.

         "Permitted Refinancing Indebtedness" means Indebtedness of the
Borrower or a Subsidiary thereof, incurred in exchange for, or the proceeds of
which are used to renew, extend, refinance, refund or repurchase, outstanding
Indebtedness of the Borrower or any Subsidiary thereof which outstanding
Indebtedness was incurred in accordance with, or is otherwise permitted by, the
terms of this Agreement, other than any such Indebtedness permitted pursuant to
clause (vii) of the definition of "Permitted Subsidiary Indebtedness"; provided
that (i) if the Indebtedness being renewed, extended, refinanced, refunded or
repurchased is pari passu with or subordinated in right of payment to the
Notes, then such Indebtedness is pari passu with or subordinated in right of
payment to, as the case may be, the Notes at least to the same extent as the
Indebtedness being renewed, extended, refinanced, refunded or repurchased, (ii)
such new Indebtedness is scheduled to mature later than the Indebtedness being
renewed, extended, refinanced, refunded or repurchased, (iii) such new
Indebtedness has an Average Life at the time such Indebtedness is incurred that
is greater than the Average Life of the Indebtedness being renewed, extended,
refinanced, refunded or repurchased and (iv) such new Indebtedness is in an
aggregate principal amount (or, if such Indebtedness is issued at a price less
than the principal amount thereof, the aggregate amount of gross proceeds
therefrom is) not





                                       22
<PAGE>   28
in excess of the aggregate principal amount then outstanding of the
Indebtedness being renewed, extended, refinanced, refunded or repurchased (or
if the Indebtedness being renewed, extended, refinanced, refunded or
repurchased was issued at a price less than the principal amount thereof, then
not in excess of the amount of liability in respect thereof determined in
accordance with GAAP); provided, further that Permitted Refinancing
Indebtedness shall not include (a) Indebtedness of a Subsidiary of the Borrower
that is incurred to renew, extend, refinance, refund or repurchase Indebtedness
of the Borrower and (b) Indebtedness (other than Non-Recourse Indebtedness of
the related Non-Recourse Subsidiary) that is incurred to renew, extend,
refinance, refund or repurchase Non-Recourse Indebtedness of such Non-Recourse
Subsidiary.

         "Person" means any individual, corporation, business trust,
association, company, limited liability entity, partnership, joint venture,
trust, unincorporated organization or governmental authority, or any agency,
tribunal, court, instrumentality or subdivision thereof, or any other form of
entity.
         "Plan" means any Pension Plan or Welfare Plan.

         "Preferred Stock" means one or more classes of capital stock of the
Borrower having a preferred or senior right, compared to some other class of
capital stock, to receive dividends or the proceeds from the voluntary or
involuntary liquidation of the Borrower.

         "Pricing Selection" means the Borrower's selection pursuant to this
Agreement of the Base Rate or the Adjusted Eurodollar Rate.

         "Prohibited Transaction" means a "prohibited transaction" within the
meaning of Section 4975 of the Code.

         "Project Finance Indebtedness" of a Person means any Indebtedness the
proceeds of which will be used solely to make capital expenditures to repair,
refurbish, upgrade or improve one or more drilling rigs already owned by such
Person or an Affiliate thereof, and such repairs, refurbishments, upgrades or
improvements are being made in connection with a drilling or workover contract
that has been entered into by such Person or an Affiliate thereof with a Person
that is not an Affiliate of such Person.

         "Property" means, with respect to any Person, any interest of such
Person in any kind of property or asset, whether real, personal or mixed, or
tangible or intangible, excluding capital stock in any other Person.

         "Pro Rata Share" means for each of the respective Banks, the Specified
Percentage.

         "Quarterly Compliance Certificate" means the certificate in form and
substance substantially similar to that which is attached hereto as Exhibit H,
with the blanks therein properly and accurately completed, and setting forth
the calculations demonstrating compliance with the financial covenants
contained in the Agreement, such certificate being signed by an Authorized
Representative of Borrower.





                                       23
<PAGE>   29
         "Quarterly Operating Loss" means Consolidated Cash Operating Income,
less depreciation and amortization, for any Quarterly Reporting Period, is a
deficit figure.

         "Quarterly Reporting Period" means each three-month period coinciding
with the period for which the Borrower submits to the SEC its quarterly report
on Form 10-Q or, in the case of the last three month period in any fiscal year
of the Borrower, its report on Form 10-K; provided, that if the Borrower is not
required to submit to the SEC quarterly reports on Form 10-Q, then Quarterly
Reporting Period means each March 31, June 30, September 30 or December 31,
except as Borrower and the Banks may otherwise agree in writing.

         "Regulation D" means Regulation D of the Board of Governors of the
Federal Reserve System as the same may be amended or supplemented from time to
time.

         "Regulatory Change" means, with respect to the Banks, any change after
the date of this Agreement in United States federal or state, or foreign
(including, without limitation, Canada and its provinces) laws or regulations
(including, without limitation, Regulation D) or the adoption or making after
such date of any interpretations, directives, or requests applying to a class
of banks including the Banks of or under any United States federal or state, or
any foreign, laws or regulations (whether or not having the force of law) by
any court or governmental or monetary authority charged with the interpretation
or administration thereof.

         "Reimbursement Obligations" means, collectively, the obligations of
the Borrower then outstanding, or which may thereafter arise in respect of
Letters of Credit then outstanding, to reimburse the Banks hereunder for the
amounts paid by the Banks in respect of drawings made under Letters of Credit.

         "Replacement Asset" means, with respect to any Asset Sale, the
Property or asset that, as determined by the Board of Directors of the Borrower
as evidenced by a resolution thereof, is used or useful in a line of business
of the Borrower or any Consolidated Subsidiary existing on the date of this
Agreement.

         "Reportable Event" shall have the meaning set forth therefor in ERISA.

         "Required Payment" means a repayment upon the Revolving Note in an
amount sufficient to reduce the sum of (i) the aggregate principal balance of
the Revolving Note and (ii) Total Letter of Credit Liabilities, to an amount
equal to or less than the then applicable Borrowing Base.

         "Reserve Requirement" means, for any Eurodollar Advance for any
Interest Period therefor, the then current maximum rate at which reserves
(including any basic, marginal, supplemental, emergency and other reserves) are
required to be maintained during such Interest Period under Regulation D by
member banks of the Federal Reserve System in New York City, New York, against
(a) in the case of Eurodollar Advances, "Eurocurrency Liabilities" (as such
term is defined in Regulation D), and (b) in general, but without duplication,
any category of deposits or liabilities as is or would be acquired, required,
incurred or desirable by Agent in





                                       24
<PAGE>   30
connection with Agent's funding of, or procuring the funding for, or the making
of, such Eurodollar Advances.  Each determination by Agent of the applicable
Reserve Requirement shall, in the absence of manifest error, be conclusive and
binding.

         "Restricted Payment" means to (i) declare or pay any dividend on, or
make any distribution in respect of, or purchase, redeem, retire or otherwise
acquire for value any capital stock of the Borrower or any Affiliates of the
Borrower, or warrants, rights or options to acquire such capital stock, other
than (x) dividends payable solely in the common stock of the Borrower or such
Affiliate, as the case may be, or in warrants, rights or options to acquire
such common stock, (y) dividends or distributions by a Subsidiary to the
Borrower or to a Wholly Owned Subsidiary (except a Non-Recourse Subsidiary),
and (z) conversion of Preferred Stock outstanding on June 16, 1994, into common
stock of the Borrower, (ii) make any principal payment on, or redeem,
repurchase, defease or otherwise acquire or retire for value, prior to any
scheduled principal payment, scheduled sinking fund payment or other stated
maturity, Indebtedness of the Borrower or any Subsidiary which is subordinated
in right of payment to the Notes or (iii) make any Investment (other than
Permitted Investments and Investments made by the Borrower in Wholly Owned
Subsidiaries (or any Person that will be a Wholly Owned Subsidiary as a result
of such Investment) except Non-Recourse Subsidiaries, or by a Subsidiary in the
Borrower or one or more Wholly Owned Subsidiaries (or any Person that will be a
Wholly Owned Subsidiary as a result of such Investment) except Non-Recourse
Subsidiaries) in any Person.

         "Revolving Loan Commitment" means the commitment of the Banks to make
Revolving Loans as set forth in Section 2.03 hereof, up to the maximum
aggregate amount of the Total Credit Commitment less $5,000,000, or such lesser
amount, as such commitment shall exist from time to time.

         "Revolving Loans" means the Loans to be made to the Borrower pursuant
to the provisions of Article II hereof.

         "Revolving Note" means the Revolving Note of the Borrower payable to
the order of each of the Banks, in substantially the form attached hereto as
Exhibit A, having the blanks therein appropriately completed and duly executed,
and otherwise in form and substance satisfactory to the Banks, together with
any and all renewals, extensions, rearrangements and/or increases.

         "Sale and Lease-Back Transaction" means, with respect to any Person,
any direct or indirect arrangement pursuant to which Property is sold or
transferred by such Person or a subsidiary of such Person and is thereafter
leased back from the purchaser or transferee thereof by such Person or one of
its subsidiaries.

         "SEC" means the Securities and Exchange Commission or any successor to
the function of such agency.

         "Security" means "security" as defined in the Securities Act of 1933,
as amended.





                                       25
<PAGE>   31
         "Security Agreement" means that certain Security Agreement dated as of
even date herewith, executed by the Borrower as "debtor" in favor of the Agent,
for the benefit of the Banks, as secured party, and creating a security
interest in each Intercompany Revolving Credit Note.

         "Significant Subsidiaries" means each Subsidiary of the Borrower that,
at any date of determination of the Subsidiaries that constitute Significant
Subsidiaries, either (i) has total assets, determined in accordance with GAAP
as of the most recent date for which a consolidating balance sheet of Borrower
and its Subsidiaries is available, of at least $10,000,000, or (ii) is listed
on Schedule 3.14 attached hereto, or (iii) has been designated, in a written
notice by Borrower delivered to Agent, as a "Significant Subsidiary", or (iv)
had total revenue (excluding revenues from Affiliates), determined in
accordance with GAAP as of the most recent date for which a consolidating
income statement from Borrower and its Consolidated Subsidiaries is available,
of at least 5% of Consolidated total revenues of Borrower and its Subsidiaries.

         "S&P" means Standard & Poor's Corporation or its successors.

         "Special Purpose Fixed Charge Coverage Ratio" means, as of the last
day of any fiscal quarter of the Borrower, the ratio of (i) Consolidated EBITDA
of the Borrower to (ii) Special Purpose Fixed Charges of the Borrower.

         "Special Purpose Fixed Charges" means, without duplication, as of the
date of calculation thereof, the amounts of (i) Consolidated Interest Expense
for the preceding four fiscal quarters, plus (ii) current scheduled maturities
of principal on Indebtedness (including the principal component of capitalized
leases) owed by the Borrower and its Consolidated Subsidiaries for the four
fiscal quarters immediately preceding the date of calculation of Special
Purpose Fixed Charges, plus (iii) all dividends on Preferred Stock of Borrower
which dividends Borrower is obligated to pay (and an obligation to pay
Preferred Stock dividends shall be deemed to exist whether or not such
dividends are cumulative) by the terms of such Preferred Stock for the four
fiscal quarters immediately preceding the date of calculation of Special
Purpose Fixed Charges, plus (iv) all Capital Expenditures made by the Borrower
or its Consolidated Subsidiaries over the four fiscal quarters immediately
preceding the date of calculation of Special Purpose Fixed Charges, less Excess
Cash on Hand (except that the amount determined for this clause (iv) shall be
deemed to be zero if it would otherwise be a negative number).

         "Specified Percentage" means, as to any of the Banks, the percentage
indicated beside its name on the signature pages hereof, or as adjusted or
specified in any Assignment and Acceptance.

         "Subsidiary" means any corporation or other Person (whether now
existing or hereafter created) of which more than 50% of the issued and
outstanding securities having ordinary voting power for the election of
directors, or more than 50% of the beneficial ownership interest, is now or
hereafter owned or controlled, directly or indirectly, by the Borrower or any
Subsidiary thereof, with the voting power and ownership of the Borrower and all
Subsidiaries aggregated together to determine whether a Person is a Subsidiary,
and "Subsidiary" shall include, without limiting the generality of the
foregoing, the Significant Subsidiaries.





                                       26
<PAGE>   32
         "Tangible Net Worth" means, at any date of determination thereof, the
Consolidated total assets of the Borrower and its Subsidiaries (valued at cost
less normal depreciation) at such date, less the sum, determined on a
Consolidated basis for the Borrower and its Subsidiaries, of (i) all
intangibles at such date, (ii) all liabilities at such date, and (iii) all
other notes, accounts or other receivables owed to Borrower by any Affiliate,
all determined on a Consolidated basis.  For purposes of this definition, the
term "intangibles" shall include, without limitation, (a) deferred charges, (b)
the amount of any write-up after December 31, 1993, in the book value of any
assets contained in any balance sheet resulting from revaluation thereof
(except as permitted by GAAP), or any write-up in excess of the cost of such
assets acquired and (c) the aggregate of all amounts appearing on the assets
side of any such balance sheet for franchises, licenses, permits, patents,
patent applications, copyrights, trademarks, trade names, goodwill, treasury
stock, experimental or organizational expenses and other like intangibles.  For
purposes of this definition, the term "liabilities" shall include as of the
date of determination of Tangible Net Worth, without limitation, (1)
Indebtedness, (2) deferred liabilities, and (3) obligations under leases which
have been capitalized or should have been capitalized in accordance with GAAP.

         "Total Credit Commitment" means $30,000,000, or such lesser amount as
the Banks and the Borrower may otherwise agree on from time to time in writing.

         "Total Letter of Credit Liabilities" means the aggregate outstanding
amount of all Letter of Credit Liabilities in respect of all Letters of Credit.

         "Tribunal" means any court, tribunal or governmental department,
commission, board, bureau, agency, or instrumentality of any state, province,
commonwealth, nation, territory, possession, county, parish, or municipality,
whether now or hereafter constituted and/or existing.

         "Triton" means Triton Engineering Services Company, a Texas
corporation, and its Subsidiaries.

         "Type" means any type of Advance (that is, a Base Rate Advance or a
Eurodollar Advance).

         "UCC" means the Uniform Commercial Code as adopted and amended in the
State of Texas.

         "UCP" means the Uniform Customs and Practice for Documentary Credits
(1993 Revision), International Chamber of Commerce Publication No. 500, as
amended and in effect from time to time.

         "U.S. Government Obligations" means securities that are (i) direct
obligations of the United States of America for the payment of which its full
faith and credit is pledged, (ii) obligations of a Person controlled or
supervised by and acting as an agency or instrumentality of the United States
of America the payment of which is unconditionally guaranteed as a full faith
and credit obligation by the United States of America, which, in either case
under clauses (i) or (ii) are not callable or redeemable at the option of the
issuer thereof or (iii) depository receipts issued by a bank or trust company
as custodian with respect to any





                                       27
<PAGE>   33
such U.S. Government Obligations or a specific payment of interest on or
principal of any such U.S. Government Obligation held by such custodian for the
account of the holder of a depository receipt; provided that (except as
required by law) such custodian is not authorized to make any deduction from
the amount payable to the holder of such depository receipt from any amount
received by the custodian in respect of the U.S. Government Obligation or the
specific payment of interest on or principal of the U.S. Government Obligation
evidenced by such depository receipt.

         "Voting Stock" means, with respect to any Person, securities of any
class or classes of capital stock in such Person entitling the holders thereof
(whether at all times or at the times that such class of capital stock has
voting power by reason of the happening of any contingency) to vote in the
election of members of the board of directors (or comparable body) of such
Person.

         "Welfare Plan" means a "welfare plan", as such term is defined in
Section 3(1) of ERISA.

         "Wholly-Owned Subsidiary" means any Subsidiary 100% of whose capital
stock (of every class or type, including warrants, rights, options and
instruments convertible into capital stock), except shares required as
directors' qualifying shares, is owned directly or indirectly by the Borrower.

         1.02    Accounting Terms and Definitions.  (a) Unless otherwise
specified herein, all accounting terms used herein shall be interpreted, all
accounting determinations hereunder shall be made, and all financial statements
required to be delivered hereunder shall be prepared, in accordance with GAAP
as in effect from time to time, applied on a basis consistent (except for
changes approved by Borrower's independent certified public accountants) with
the most recent financial statement of Borrower delivered to the Agent.  All
other terms used herein shall have the meanings as otherwise stated herein or
as otherwise defined in the Code.

         (b)     All terms defined in this Agreement shall have their defined
meanings when used in each of the other Loan Documents, unless any such
instruments shall expressly indicate otherwise, and when required by the
context, each term shall include the plural as well as the singular.
Definitions of each Person specifically defined herein or in each other Loan
Document shall mean and include herein and therein, unless otherwise expressly
provided to the contrary, the successor, assigns, heirs and legal
representatives of each such Person.  Unless the context otherwise requires or
unless otherwise expressly provided, references to this Agreement and each
other Loan Document shall include all amendments and modifications thereof or
thereto, as applicable and as in effect from time to time.

         (c)     Each reference herein to a section, or any subdivision
thereof, shall refer to the applicable section or subdivision thereof, of this
Agreement, unless another instrument is thereby expressly referenced.  The
headings in this Agreement and the other Loan Documents are inserted for
convenience only and shall be ignored when construing any such instruments.





                                       28
<PAGE>   34
                        ARTICLE II -- CREDIT FACILITIES

         2.01    Extensions of Credit.  (a) Subject to the terms and conditions
of this Agreement, each of the Banks severally agrees to lend to the Borrower,
and the Borrower has the right to borrow from each of the Banks, from time to
time during the period from the date hereof to and including the Credit
Maturity Date, amounts not to exceed at any one time outstanding such Bank's
Specified Percentage of the Revolving Loan Commitment, provided, however, that
(i) the sum of the aggregate principal amount of all Revolving Loans by the
Banks at any one time outstanding together with all Letter of Credit
Liabilities shall not exceed the lesser of (a) the Total Credit Commitment, and
(b) the Borrowing Base in effect from time to time, and (ii) the aggregate
principal amount of all Revolving Loans by the Banks at any one time
outstanding shall not exceed the lesser of (a) $25,000,000 and (b) the Total
Credit Commitment and (iii) all Letter of Credit Liabilities shall not exceed
$5,000,000.  The credit described in the preceding sentence shall be a
revolving credit entitling the Borrower to borrow, prepay and reborrow by means
of Advances of any Type in accordance with the terms hereof.  Each Type of
Advance shall be made at Agent's Applicable Lending Office for such Type of
Advance.

         (b)     All Loans under this Agreement shall be made by the Banks
simultaneously and in proportion to their Specified Percentages of the
Revolving Loan Commitment.  None of the Banks shall be responsible for any
default by any other Bank regarding that other Bank's obligation to make a Loan
and participate in the issuance of a Letter of Credit hereunder.  The Agent
shall make such minor technical adjustments among the Banks as may be necessary
or appropriate with respect to the allocation of final Loans and participations
in the Letters of Credit or repayments among the Banks in order that such Loans
and participations in the Letters of Credit and repayments of the Note or other
Obligations, which shall have been divided among the Banks on the basis of
their Pro Rata Shares, correspond exactly to the Commitments and the Loans and
participation in the Letters of Credit or repayments of the Note or other
Obligations severally due from or to each of the Banks.

         (c)     Notwithstanding any terms or provisions to the contrary herein
contained or referenced, the Banks shall have no commitment to make any Loan to
Borrower or to issue any Letter of Credit on behalf of Borrower if at the time
of the request therefor any of the following conditions shall have occurred and
be continuing: (i) any representation or warranty made herein or in any other
Loan Document (other than those representations and warranties that are by
their express terms limited to the date of the instrument in which they are
initially made or in respect to which each such change shall be and has been
communicated, in writing to the Agent and approved, in writing, by the Agent)
is not true and correct in all material respects at such time as though made on
and as of such time; (ii) there has been a material adverse change in the
condition, financial or otherwise, of Borrower and the Significant Subsidiaries
taken as a whole; (iii) there exists, or will exist, upon the making of such
Loan, a Default or an Event of Default; or (iv) with respect to any Revolving
Loan, the Agent shall not have timely received a Loan Formula Certificate
appropriately completed, duly executed and accompanied by any required
documentation.

         2.02    Extensions of Maturity.  Upon written request by the Borrower
received by the Agent at least 90 days but not more than 120 days prior to each
one year anniversary hereof





                                       29
<PAGE>   35
until the Credit Maturity Date, the Banks (by unanimous written consent only)
and the Borrower shall review the credit facilities provided for herein, and
the Banks (by unanimous written consent only, expressed to Borrower within 60
days of receipt of Borrower's written request for extension of the Credit
Maturity Date) and the Borrower, at that time, may mutually agree to extend the
Credit Maturity Date for one year from the date of the Credit Maturity Date as
set forth herein.  No credit extensions beyond the two one-year extensions
will be considered hereunder, and in no event shall the Credit Maturity Date be
later than June 9, 1998.  If, at the time of any of the above described reviews
of the credit facilities provided herein, all of the Banks and the Borrower do
not mutually agree to extend the Credit Maturity Date, then such date shall not
be extended, and the undertaking to review and consider the credit facilities
and the extension of the Credit Maturity Date as set forth herein above shall
not be construed to create hereby any obligation on the part of the Banks to
renew or extend the Credit Maturity Date, such determination to renew and
extend the Credit Maturity Date being in the sole and absolute discretion of
the Banks.

         2.03    Manner of Borrowing.  (a) The Borrower shall give to the Agent
on or before 12:00 noon Houston, Texas time at least three Business Days prior
to the requested date for a Eurodollar Advance and at least one Business Day
prior to the requested date for a Base Rate Advance, written notice in the form
of a Loan Request Form for each requested Revolving Loan hereunder, specifying
the amount of such Advance, the Pricing Selection and the desired Interest
Period.  Each Advance shall be in the aggregate principal amount of $1,000,000
or an integer multiple thereof.

         (b)     Each Loan Request Form shall be irrevocable and binding on the
Borrower, and the Borrower agrees hereby to indemnify each of the Banks against
any cost, loss or expense incurred by any such Bank as a result of any failure
to fulfill, on or before the date specified for a borrowing, the conditions to
such borrowing set forth herein, including, without limitation, any cost, loss
or expense incurred by reason of the liquidation or reemployment of deposits or
other funds acquired by any such Bank to fund the Loan to be made by such Bank
as part of such borrowing.  Any such costs, losses or expenses incurred by any
of the Banks shall be accompanied by the Agent's written summary explanation
thereof.

         (c)     Upon receipt of the Loan Request Form, the Agent shall give
each of the Banks telephonic notice (confirmed in writing) of the requested
Loan, of each of the Banks' Specified Percentage thereof, of the applicable
interest rate and of any other matters set forth in the Loan Request Form.
Each of the Banks shall, before 10:30 A.M. Houston, Texas time on the requested
Borrowing Date, make available (for the account of the Agent) to the Agent at
its Payment Office, in same day funds the amount of such Bank's Specified
Percentage of the Loan.  Upon the Agent's receipt of such funds and fulfillment
of the applicable conditions set forth in Article VIII hereof, the Agent will,
at or prior to 12:00 noon, make the amount of the requested Loan available to
the Borrower by deposit of the proceeds of such Loan to Borrower's demand
deposit account maintained with the Agent in Houston, Texas.

         (d)     Unless the Agent shall have received notice from any of the
Banks prior to the requested borrowing date that such Bank will not make
available to the Agent funds in the amount of such Bank's Specified Percentage
of the Loan, the Agent may assume that such Bank





                                       30
<PAGE>   36
has made such portion available to the Agent on the Borrowing Date in
accordance with Section 2.03(c) and the Agent may, in reliance upon such
assumption, make available to the Borrower on such date a corresponding amount.
If and to the extent that such Bank shall not have so made such Specified
Percentage available to the Agent and the Agent shall have so made such
corresponding amount available to the Borrower, Agent shall use its best
efforts to promptly notify such Bank and the Borrower of such failure to pay
(although any failure by Agent to effect such notice shall not void the rights
of the Agent or the Banks, or the Banks' or the Borrower's obligation to
reimburse, as hereinafter set forth, such Bank and the Borrower severally agree
to repay to the Agent, forthwith on demand such corresponding amount together
with interest thereon, for each day from the date such amount is made available
to the Borrower until the date such amount is repaid to the Agent, at (i) in
the case of the Borrower, the interest rate applicable at the time to the
Eurodollar Advance or the Base Rate Advance, as the case may be, comprising
such Loan and (ii) in the case of such Bank, the Federal Funds Rate; provided,
however, that the Agent shall not be entitled to recover more than one
satisfaction from Borrower and such Bank of such amount funded, together with
interest thereon.  If such Bank shall repay to the Agent such corresponding
amount, such amount so repaid shall constitute such Bank's advance as part of
the Loan for purposes of this Agreement and Borrower shall thereupon be
obligated to repay such advance in accordance with the terms and conditions
hereof.

         (e)     If no Interest Period with respect to any Advance is specified
by the Borrower in the Loan Request Form, then the Borrower shall be deemed to
have requested the shortest Interest Period available under the terms hereof
with respect to such Advance.  Each Loan shall be evidenced by a promissory
note of the Borrower in the form of a Note, dated the date of this Agreement
and payable on or before the Credit Maturity Date all as set forth therein.
Each of the Banks may endorse on a schedule attached to each Note held by it an
appropriate notation evidencing each Advance and each payment made on account
of the principal and interest on such Advance; provided, however, that the
failure to make such a notation on any Note with respect to any Advance shall
not limit or otherwise affect the obligation of the Borrower hereunder or under
any Note with respect to any Advance or any other obligations, and payments of
principal or interest on each Advance shall not be affected by the failure to
make a notation thereof on said schedule.

         (f)     Each Advance shall bear interest on the unpaid balance of the
principal amount thereof from the date such Advance is made until paid in full
at a varying per annum rate of interest equal from day to day to the sum of (i)
the Applicable Rate, plus (ii) the Applicable Margin, each such change in the
rate of interest charged on each outstanding Advance to become effective,
without notice to the Borrower or any other Person, on the effective date of
each change in the Applicable Rate, the Applicable Margin or the Operating Loss
Increment, as the case may be.  As a result of the means of and timing for
calculation for the Operating Loss Increment, the Borrower may be required from
time to time to pay additional interest on an Advance with respect to which the
Borrower had previously paid certain accrued unpaid interest, and Borrower
shall pay to the Agent, for the benefit of the Banks, upon demand by the Agent
such additional interest on Advances (whether or not such Advances are then
outstanding) as results from the determination that the Operating Loss
Increment applied to a prior period of time.





                                       31
<PAGE>   37
         (g)     Accrued and unpaid interest on all Advances shall be due and
payable as follows:  (i)  in the case of each Base Rate Advance, or Eurodollar
Advance, on each Interest Payment Date, and (ii)  in the case of any Advance,
when such Advance shall be due (whether at maturity, by reason of prepayment,
scheduled due date, acceleration or otherwise), or converted into an Advance of
another Type but only to the extent accrued on the amount then due or
converted.  All unpaid principal and accrued unpaid interest shall be due and
payable on the Credit Maturity Date.

         (h)     Without duplication of the provisions of Section 2.04 hereof,
all past due principal, and, to the maximum extent permitted by Applicable Law,
all past due interest on Advances under this Agreement, the Notes and other
amounts herein and under each other Loan Document due, shall bear interest on
the amounts thereof from time to time remaining unpaid (both before and after
judgment) at the Default Rate.

         (i)     In no event shall the sum of (X) the aggregate unpaid
principal amount of the Revolving Loans outstanding and (Y) the Total Letter of
Credit Liabilities exceed the lesser of (A) the Total Credit Commitment and (B)
the Borrowing Base.

         (j)     In the event that, at any time or from time to time, the sum
of (i) the aggregate principal amount of the Revolving Loans and (ii) Total
Letter of Credit Liabilities exceeds the lesser of (a) the Total Credit
Commitment and (b) the Borrowing Base in effect at such time, then the Borrower
shall, within five (5) Business Days after submission of a Loan Formula
Certificate evidencing same, make a Required Payment in an amount such that no
such excess shall exist, provided that if necessary to cover any such excess
after prepaying the Revolving Loans in full, the Borrower shall pay to the
Banks for credit to the Collateral Account an amount such that no such excess
will exist.  The Agent shall give to the Borrower written notice of each
determination that any Eligible Account submitted for inclusion in or included
in the Borrowing Base is unacceptable or deficient, for the reasons specified
in the notice and that such Eligible Account is therefore not a part or no
longer a part of the Borrowing Base, and the Borrower shall within 30 days
after such notice, make a Required Payment.  In addition to the foregoing,
should the aggregate unpaid principal balance under the Notes at any time
exceed the Borrowing Base then in effect, the Borrower shall within five (5)
Business Days after demand by the Agent, make a Required Payment.

         (k)     The Notes, in addition to the applicable terms and provisions
hereof and referenced herein, shall otherwise be subject to, and governed by
the terms and provisions therein set forth and referenced and such terms and
provisions incorporated herein for all purposes.

         2.04    Conversions and Continuations.  The Borrower shall have the
right from time to time to convert all or a part of one Loan or Type of Advance
into another Loan or Type of Advance or to continue all or part of any Loan by
giving Agent written notice pursuant to a Loan Request Form at least three (3)
and not more than seven (7) Business Days before conversion into or
continuation of an Advance, specifying:  (i) the conversion or continuation
date, (ii) the amount of the Loan or Advance to be converted or continued,
(iii) in the case of conversions, the Loan or Type of Advance to be converted
into, and (iv) in the case of a





                                       32
<PAGE>   38
continuation of or conversion into a Eurodollar Advance, the duration of the
Interest Period applicable thereto; provided that neither Base Rate Advances
nor Eurodollar Advances may be converted to, or, on the last day(s) of the then
current Interest Period(s) for outstanding Eurodollar Advances, continued as,
as applicable, Eurodollar Advances, after the occurrence of an Event of Default
or Default, or so long as any Regulatory Change has the consequences described
in Section 2.14, or when any of the conditions referred to in Section 8.02(a),
(b), (c) and (d) are not then met.  Eurodollar Advances shall only be converted
or continued on the last day of the Interest Period for such Eurodollar
Advances.  All notices given under this Section shall be irrevocable and shall
be given not later than 12:00 noon, Houston, Texas time, on the day which is
not less than the number of Business Days specified above for such notice.  If
Borrower shall fail to give to Agent the notice as specified above for
continuation or conversion of a Eurodollar Advance prior to the end of the
Interest Period with respect thereto, then such Eurodollar Advance, on the last
day of the Interest Period for such Eurodollar Advance shall automatically be
converted into a Base Rate Advance.  Upon the occurrence of an Event of
Default, the Agent may convert all Eurodollar Advances to Base Rate Advances,
and the Borrower agrees to pay any and all costs and expenses associated with
or related to such conversion(s) of its Eurodollar Advances.  The provisions of
the immediately preceding sentence notwithstanding, however, (i) the provisions
of such sentence shall not limit in any respect the obligation of the Borrower
to pay interest at the Default Rate on all past due principal and, to the
maximum extent permitted by Applicable Law, all past due interest, whether by
acceleration or otherwise, as provided herein, and (ii) after the occurrence
and during the continuance of an Event of Default, all Base Rate Advances shall
bear interest at a rate per annum equal to the Default Rate rather than the
Base Rate.

         2.05    Use of Proceeds of Advances.  The proceeds of each Advance
shall be used by the Borrower solely for its working capital needs.

         2.06    Fees.

         (a)     Commitment Fee.  The Borrower agrees to pay to the Agent for
the account of each of the Banks a commitment fee equal to .375% per annum on
the average daily unused portion of the Total Credit Commitment (determined by
subtracting the aggregate amount of all outstanding Revolving Loans then
outstanding and the face amount of Letters of Credit issued and outstanding and
the aggregate of any amounts advanced under any Letter of Credit and not yet
reimbursed from the Total Credit Commitment) computed on the basis of the
actual number of days elapsed over a year of 365 or 366 days, as the case may
be.  Such commitment fee with respect to the Total Credit Commitment shall
accrue from and including the date hereof to but excluding the Credit Maturity
Date (including all extensions thereof) and shall be payable quarterly in
arrears commencing on the last Business Day of June, 1994 and continuing on the
last Business Day of each September, December, March and June thereafter until
the Credit Maturity Date (including all extensions thereof).  Pursuant to
Section 2.07 hereof, the Borrower shall have the right to permanently reduce
the Total Credit Commitment; and any such permanent reduction or termination of
the Total Credit Commitment shall proportionately reduce or terminate the
commitment fee otherwise payable pursuant to this Section 2.06(a) as of the
date on which the Total Credit Commitment is so permanently reduced or
terminated.





                                       33
<PAGE>   39
         (b)     Letter of Credit Fees and Commissions.  The Borrower agrees to
pay to the Agent for the account of First Interstate a fee for issuing the
Letters of Credit (calculated separately for each Letter of Credit) equal to
.125% per annum of the maximum liability of the Banks existing from time to
time under such Letter of Credit, payable quarterly in arrears on the last
Business Day of each June, September, December and March during the period that
such Letter of Credit is outstanding.  The Borrower additionally agrees to pay
to the Agent for the benefit of the Banks in proportion to their Specified
Percentages commissions for issuing the Letters of Credit (calculated
separately for each Letter of Credit) equal to 1.125% per annum of the maximum
liability of the Banks existing from time to time under such Letter of Credit.
All such fees shall be payable quarterly in arrears on the last Business Day of
each March, June, September and December up to, but including on, the Credit
Maturity Date, and Borrower shall also pay such other fees as First Interstate
may customarily charge and set forth in the Application.  To the extent that
any outstanding Letter of Credit is amended, the Borrower shall pay to the
Agent for the account of First Interstate an amendment commission of $30 per
amendment.

         (c)     Fee at Closing.  Borrower shall pay at closing to the Agent
for the account of each of the Banks party hereto at closing a fee in the
amount of .5% of the Total Credit Commitment.

         2.07    Reduction or Termination of Revolving Credit Commitment.
Subject to the provisions hereof, the Borrower may at any time or from time to
time permanently reduce the Total Credit Commitment or permanently terminate in
whole the Total Credit Commitment by giving not less than two (2) Business
Days' prior written notice to such effect to the Agent, provided that (a) any
partial reduction of the Total Credit Commitment shall be in an aggregate
amount of not less than $1,000,000 and (b) unless the Borrower shall provide to
the Agent for the benefit of the Banks cash in an amount sufficient to satisfy
and secure the payment in full of all Letter of Credit Liabilities in excess of
the Total Credit Commitment as so reduced, in no event shall Borrower be
entitled to terminate or reduce the Total Credit Commitment if, after giving
effect thereto, the Total Credit Commitment would be less than the sum of the
aggregate amount of all outstanding Revolving Loans plus the Total Letter of
Credit Liabilities.

         2.08    Letters of Credit.  Subject to all the terms of this
Agreement, prior to the Credit Maturity Date First Interstate agrees to issue,
renew and extend Letters of Credit, and each of the Banks agrees to maintain a
participation interest, to the extent of the Specified Percentage of each, in
all such Letters of Credit; provided that in no event shall Total Letter of
Credit Liabilities exceed nor shall any Letter of Credit be issued, renewed or
extended which would result in Total Letter of Credit Liabilities exceeding,
the lesser of (i) $5,000,000, (ii) the Total Credit Commitment, and (iii) the
Borrowing Base.  Each Letter of Credit shall be issued by First Interstate with
the Banks each participating based on their respective Specified Percentages,
shall be for the account of the Borrower or any of its Subsidiaries, shall have
an expiration date prior to the Credit Maturity Date and shall be for the
purpose of securing the contractual obligations of the Borrower or any of its
Subsidiaries, provided however, that neither the Agent, First Interstate nor
any of the other Banks shall be obligated to issue any Letter of Credit if the
face amount thereof would exceed the various limits on the Total Letter of
Credit Liabilities as set forth in this Agreement.  If First Interstate makes a
payment under any Letter of Credit and the





                                       34
<PAGE>   40
Borrower has not made available to First Interstate sufficient funds to honor
such payment, each of the Banks other than First Interstate will forthwith upon
request forward to or deposit with Agent for the account of First Interstate an
amount equal to its Specified Percentage of such payment, with interest as set
forth in Section 2.10 hereof.  Such deposit by the Banks shall not relieve the
Borrower from its reimbursement obligations under the applicable Application or
hereunder.

         2.09    Notice and Manner of Obtaining Letters of Credit.  (a)  The
beneficiary, amount and date of issuance, renewal, extension or reissuance of a
Letter of Credit pursuant to this Agreement shall be designated in an
Application therefor, together with a Loan Request Form, delivered by Borrower
to the Agent and to First Interstate at least four Business Days prior to the
requested date of such issuance, renewal, extension or reissuance.  All Letters
of Credit issued hereunder shall expire on or before the Credit Maturity Date,
except that Letters of Credit may be issued which expire no later than one year
after the Credit Maturity Date, provided that the Borrower shall have first
provided (prior to such issuance) to the Agent for the benefit of the Banks,
cash in an amount sufficient to satisfy and secure the payment in full of all
Letter of Credit Liabilities that could be due within such one year period
after the Credit Maturity Date.

         (b)     The Borrower assumes all risks of the acts or omissions of
beneficiaries of any of the Letters of Credit with respect to their use of the
Letters of Credit.  Except in the case of bad faith, gross negligence, or
wilful misconduct on the part of the Agent or any of its employees or
corespondents, neither the Agent nor its correspondents shall be responsible
for the validity or genuineness of certificates or other documents, even if
such certificates or other documents should in fact prove to be invalid,
fraudulent or forged; for errors, omissions, interruptions or delays in
transmissions or delivery of any messages by mail, telex, or otherwise, whether
or not they be in code; for errors in translations or for errors in
interpretation of technical terms; or for any other consequences arising from
causes beyond the Agent's control or the control of the Agent's correspondents,
nor shall the Agent be responsible for any error, neglect, or default of any of
the Agent's correspondents; and none of the above shall affect, impair or
prevent the vesting of any of the Agent's rights or powers hereunder or under
the Application, all of which rights shall be cumulative.  The Agent and the
Agent's correspondents may accept certificates or other documents that appear
on their face to be in order, without responsibility for further investigation.
In furtherance and not in limitation of the foregoing provisions, the Borrower
agrees that any reasonable action taken by the Agent or by any correspondent of
the Agent in good faith in accordance with any Letter of Credit, or any related
drafts, certificates, documents or instruments, shall be binding on the
Borrower and shall not put the Agent or the Agent's correspondents under any
resulting liability to the Borrower.

         (c)     The Borrower agrees that the UCP shall be binding on the
Borrower, its Subsidiaries, the Agent and the Banks with respect to Letters of
Credit, except to the extent otherwise expressly agreed in writing.
Notwithstanding the foregoing, but without limiting the effect of Section
2.09(d) hereof: (i) the Agent is authorized to make payments under Letters of
Credit upon the presentation of the documents provided for therein and without
regard to whether the Borrower or any of its Subsidiaries has failed to fulfill
any of its respective obligations under any of the Loan Documents or any other
Default has occurred; (ii) the Agent shall be entitled to rely upon any
certificate, notice, demand or other communication (whether





                                       35
<PAGE>   41
by cable telegram, telecopy, telex or otherwise), believed by it to be genuine
and to have been signed or sent by the proper Person or Persons, and upon
advice of legal counsel selected by First Interstate (and no such reliance or
failure shall place First Interstate under any liability to the Borrower or
limit or otherwise affect any obligations of Borrower under this Agreement);
(iii) any action, inaction or omission on the part of First Interstate under or
in connection with the Letters of Credit or the related instruments or
documents, if in good faith and in conformity with such laws, regulations or
customs as First Interstate may reasonably deem to be applicable, shall be
binding upon the Borrower (and shall not place First Interstate under any
liability to the Borrower or limit or otherwise affect the Borrower's
obligations under this Agreement); and (iv) notwithstanding any change or
modification in any Letter of Credit or any instruments or documents called for
thereunder, including waiver of noncompliance of any such instruments or
documents with the terms of any Letter of Credit, this Agreement shall be
binding on the Borrower and its Subsidiaries with regard to such Letter of
Credit as so changed or modified, and to any action taken by First Interstate
relative thereto.

         (d)     Without affecting any rights the Agent or the Banks may have
under applicable law (including under the UCP), the Borrower agrees that
neither the Agent, the Banks nor any of their respective officers or directors
shall be liable or responsible for, and the obligations of the Borrower to
First Interstate hereunder shall not in any manner be affected by: (x) the use
which may be made of any Letter of Credit or the proceeds thereof by the
beneficiary or any other Person or any other act or omission of any beneficiary
or other Person; (y) the validity, sufficiency, enforceability or genuineness
of documents other than the Letter of Credit, or of any endorsement(s) thereon,
even if such documents should, in fact, prove to be in any or all respects
invalid, insufficient, fraudulent or forged or any statement therein proves to
be untrue or inaccurate in any respect whatsoever; or (z) any other
circumstances whatsoever in making or failing to make payment under any Letter
of Credit, except that the Borrower shall have a claim against First
Interstate, and First Interstate shall be liable to the Borrower, to the
extent, but only to the extent, of any direct, as opposed to consequential,
damages suffered by the Borrower which the Borrower proves are caused by First
Interstate's willful misconduct or gross negligence in determining whether
documents presented under any Letter of Credit complied with the terms of such
Letter of Credit or First Interstate's willful failure to pay under such Letter
of Credit after the presentation to it of documents strictly complying with the
terms and conditions of such Letter of Credit.  In furtherance and not in
limitation of the foregoing, First Interstate may accept documents that appear
on their face to be in order, without responsibility of further investigation.

         2.10    Obligation to Reimburse and to Prepay.  The Borrower's
obligations with respect to each and every Letter of Credit shall be absolute,
irrevocable and unconditional and shall be performed strictly in accordance
herewith.  Upon receipt by First Interstate of any demand for payment under
such Letter of Credit, First Interstate shall promptly notify the Borrower of
the amount to be paid pursuant to such demand and the respective payment date.
If the Borrower does not provide First Interstate with funds, in the amount and
on the date necessary to satisfy First Interstate's obligation under a Letter
of Credit which has been presented for payment by the holder thereof (whether
at or prior to the expiration of such Letter of Credit), then the Banks, if
possible under the terms thereof, shall advance funds as a Base Rate Advance in
an amount necessary to satisfy First Interstate's payment obligation under such
Letter of Credit.





                                       36
<PAGE>   42
If such Loan is not permissible hereunder, then amounts owed to First
Interstate, as a result of payments by First Interstate pursuant to any Letter
of Credit presented for payment, shall be immediately due and payable by the
Borrower and shall bear interest at the Default Rate until paid in full by the
Borrower.  Each of the Banks shall, if such Base Rate Advance cannot be made
and if the Borrower does not make such payments with respect to such Letter of
Credit, make a payment to First Interstate, with interest at the Federal Funds
Rate from the date First Interstate made demand for such payment from the
Banks, equal to such Bank's Specified Percentage of the Letter of Credit
presented for payment.  The Agent's determination of the amounts owed to First
Interstate by the Borrower for the benefit of the Banks in connection with
payments by First Interstate pursuant to a Letter of Credit presented for
payment shall, absent manifest error, be presumed correct by and with respect
to Borrower.  Any repayments by Borrower to First Interstate on account of a
disbursement under any Letter of Credit shall be for the pro rata benefit of
those Banks which advanced funds to First Interstate in accordance with their
respective Specified Percentage participation interests in the applicable
Letter of Credit.  With respect to the Borrower's reimbursement obligations and
without limitation as to any other provision hereof, each participating Bank
may, to the fullest extent permitted by law, exercise all rights of payment
(including set off) with respect to such participation as if such Bank were the
direct creditor of the Borrower.

         2.11    Method of Payment.  All payments of principal, interest and
other amounts to be paid by the Borrower hereunder, under the Notes and under
any other Loan Document shall be made, in Dollars to Agent at the Applicable
Lending Office and by wire transfer of immediately available funds, no later
than 12:00 noon Houston, Texas time at such Applicable Lending Office on the
date on which payment shall become due, and each such payment made after such
time on such due date shall be deemed to have been made on the next succeeding
Business Day.  Whenever any payment hereunder, under the Notes or under any
other Loan Document shall be stated to be due on a day that is not a Business
Day, such payment may be made on the next succeeding Business Day and interest
or Commitment Fees, as the case may be, shall continue to accrue during such
extension.

         2.12    Prepayment; Compensation.  (a) Subject to Section 2.12(b)
hereof, Borrower may, upon at least one Business Day's prior written notice to
Agent in the case of Base Rate Advances, and at least three Business Days prior
written notice to Bank in the case of any Eurodollar Advance, prepay the Notes
in whole at any time or from time to time in part, such prepaid amounts to be
delivered to each of the Banks in accordance with the Specified Percentages but
with accrued interest to the date of prepayment on the amount so prepaid;
provided that (i) each Eurodollar Advance prepaid, or converted in accordance
with Sections 2.14 or 2.16, on a day other than the last day of the Interest
Period for such Advance, must be accompanied by the payment described in
Section 2.12(b), and (ii) each partial prepayment shall be in the principal
amount of $US 1,000,000 or an integer multiple thereof.

         (b)  The Borrower shall pay to Agent, upon the request of any of the
Banks, such amount or amounts as shall be sufficient (in the reasonable opinion
of any such Bank) to compensate them for any loss, cost, damages, liabilities
or expense incurred by each as a result of (i) any payment, prepayment or
conversion of a Eurodollar Advance on a date other than the last day of an
Interest Period for such Advance; or (ii) any failure by the Borrower to
borrow, convert,





                                       37
<PAGE>   43
or prepay a Eurodollar Advance on the date for such borrowing, conversion, or
prepayment, specified in the relevant notice of borrowing, prepayment, or
conversion under this Agreement.

         2.13    Computation of Interest.  Interest on Eurodollar Advances
shall be computed on the basis of a year of 360 days and the actual number of
days elapsed (including the first day but excluding the last day) occurring in
the period for which payable, unless such calculation would result in a
usurious rate or amount of interest under Applicable Law, in which case
interest shall be calculated on the basis of a year of 365 or 366 days, as the
case may be, and the actual number of days elapsed (including the first day but
excluding the last day) occurring in the period for which payable.  Interest on
Base Rate Advances shall be computed on the basis of a year of 365 or 366 days,
as the case may be, and the actual number of days elapsed (including the first
day but excluding the last day) occurring in the period for which payable.

         2.14    Increased Costs; Regulation.  (a)  Borrower agrees, that if
the effect of any change in any applicable law, rule, regulation, guideline or
requirement (whether or not having the force of law) or in the interpretation
or administration thereof by any central bank or other governmental agency
charged with the administration thereof (other than an increase in the rate of
tax on net income of any of the Banks) is

         (i)     to increase the cost to any of the Banks of honoring their
                 respective commitments to lend hereunder or of making or
                 maintaining any Loans hereunder;

         (ii)    to reduce any of the Banks' return hereunder or on its
                 capital, or to reduce the principal, interest, or other sums
                 received or receivable by any of the Banks hereunder by virtue
                 of any Loans hereunder or otherwise;

         (iii)   to require the inclusion of any commitment or Loans hereunder,
                 in whole or in part, in calculations related to any of the
                 Banks' capitalization or reserve requirements or to change the
                 requirements of such calculation or to increase any of the
                 Banks' capital or reserve requirements thereby, as a result of
                 any of which the profitability to any of the Banks of this
                 Agreement or any Loans hereunder is adversely affected; or

         (iv)    to impose any other condition or change affecting this
                 Agreement or any of such extensions of credit or liabilities
                 or commitments;

then Borrower shall pay to the Agent for the benefit of each of the Banks so
affected such additional amount as shall compensate such Banks for any of the
foregoing additional costs or reductions ("Additional Costs").  The Agent shall
use its best efforts to deliver promptly to the Borrower a written summary
overview of the Additional Costs.  Such Additional Costs shall be due and
payable on the next succeeding Interest Payment Date following the event
causing such additional cost or reduction to each such Bank (and the additional
amount or amounts determined by each such Bank shall be conclusive and binding
on Borrower except in the case of manifest error).





                                       38
<PAGE>   44
         (b)     Without limiting the effect of the foregoing provisions of
this Section, in the event that, by reason of any Regulatory Change, (i) any of
the Banks incur Additional Costs based on or measured by the excess above a
specified level of the amount of a category of deposits or other liabilities of
such Bank which includes deposits by reference to which the interest rate on
Eurodollar Advances or any other Loans is determined as provided in this
Agreement or a category of extensions of credit or other assets of such Bank
which includes Eurodollar Advances, or other Loans or other financial
accommodations, or (ii) any of the Banks becomes subject to restrictions on the
amount of such a category of liabilities or assets which it may hold, or (iii)
the extension or funding by any of the Banks of any Advance, Letter of Credit
or other financial accommodation hereunder, or the performance of any agreement
or obligation by any of the Banks hereunder would be prohibited or materially
restricted, then, if such Bank so elects, by notice to the Borrower, the
obligation of any of the Banks to make additional such Loans or Advances of
such Type or other financial accommodations hereunder shall be suspended until
such Regulatory Change ceases to be in effect.

         (c)     Determinations and allocations by the Agent on behalf of any
of the Banks for purposes of this Section of the effect of any Regulatory
Change on such Bank's costs of maintaining its obligations to make Loans or of
making or maintaining Loans or on amounts receivable by it in respect of Loans,
and of the additional amounts required to compensate any of the Banks in
respect of any Additional Costs, shall, in the absence of manifest error, be
conclusive and binding.

         (d)     Notwithstanding any other provision of this Agreement, in the
event that any governmental or central bank consent, approval, authorization or
license necessary to enable the Borrower to comply with its obligations under
any Loans, shall be modified, revoked, withdrawn or withheld, or in the event
that it becomes unlawful or impossible for any of the Banks or the Applicable
Lending Office of Agent to honor its obligation to make, maintain or continue
Eurodollar Advances hereunder, then Agent, upon notification thereof by the
affected Banks, shall promptly notify the Borrower thereof and (A) such Bank's
obligation to make or continue the affected Type of Advance or Loan and to
convert other Types of Advances into the affected Type of Advance or Loan
hereunder shall be suspended until such time as such Bank may again make and
maintain such affected type of Advance or Loan (in which case the provisions of
Section 2.16 hereof shall be applicable) and (B) such Bank may immediately
terminate the affected Loans, and in any such event the total principal amount
of the Loans and all accrued unpaid interest thereon, immediately shall become
due and payable without presentment, demand, or any other notice of any kind,
all of which are hereby expressly waived, and such payment then due shall be
deemed a prepayment for purposes of this Article II; provided however, such
Bank agrees that it will use reasonable efforts to designate an alternate
lending office with respect to any Eurodollar Advance affected by the matters
or circumstances described in this Section 2.14 to avoid the results provided
in this Section 2.14, so long as such designation is not disadvantageous to
such Bank as determined by it in its sole discretion.

         (e)     Each Bank shall notify Agent, which shall notify the Borrower,
of any event that for which such Bank intends to request compensation under
this Section 2.14 as promptly as practicable, but in any event within 90 days,
after such Bank obtains actual knowledge thereof; provided, that (i) if such
Bank fails to give such notice within 90 days after it obtains actual





                                       39
<PAGE>   45
knowledge of such an event, such Bank shall, with respect to compensation
payable pursuant to this Section 2.14 in respect of any costs resulting from
such event, only be entitled to payment under this Section 2.14 for costs
incurred from and after the date 90 days prior to the date that such Bank does
give such notice and (ii) such Bank will designate a different Applicable
Lending Office for the Loans affected by such event if such designation will
avoid the need for, or reduce the amount of, such compensation and will not, in
the sole opinion of such Bank, be disadvantageous to such Bank, except
that such Bank shall have no obligation to designate an Applicable Lending
Office located in the United States of America. Each Bank will furnish to the
Borrower a certificate setting forth the basis and amount of each request by
such Bank for compensation under this Section 2.14.  Determinations and
allocations by a Bank for purposes of this Section 2.14 of the effect of any
Regulatory Change pursuant to this Section 2.14 on its rate of return on or
costs of maintaining Loans or its obligation to make Loans, or on amounts
receivable by it in respect of Loans, and of the amounts required to compensate
such Bank under this Section 2.14, shall, absent manifest error, be conclusive.

         2.15    Limitation on Types of Advances.  Anything herein to the
contrary notwithstanding, if with respect to any Eurodollar Advances for any
Interest Period therefor:

                 (a)      any of the Banks determines that quotations of
         interest rates for the relevant deposits referred to as "Eurocurrency
         Liabilities" in Regulation D in Section 1.01 hereof are not being
         provided in the relative amounts or for the relative maturities for
         purposes of determining the rate of interest for such Advances as
         provided in this Agreement; or

                 (b)      any of the Banks determines that the relevant rates
         of interest referred to in the definition of "Eurodollar Rate" in
         Section 1.01 hereof on the basis of which the rate of interest for
         such Advances for such Interest Period is to be determined do not
         accurately reflect the cost to such Banks of making or maintaining
         such Advances for such Interest Period;

then the Agent may give to the Borrower notice thereof no later than 12:00
p.m., Houston, Texas time on the Business Day following the day of receipt by
Agent of a properly completed Loan Request Form, which notice shall specify the
relevant Type of Advances and the relevant amounts or periods, and so long as
such condition remains in effect, Banks shall be under no obligation to make
additional Advances of such Type or to convert Advances of any other Type into
Advances of such Type.

         2.16    Substitute Base Rate Advances.  If the obligation of any Bank
to make, convert and/or continue any Type of Eurodollar Advances shall be
suspended pursuant to Section 2.14 or 2.15 hereof (Advances of such Type being
herein called "Affected Advances" and such Type being herein called the
"Affected Type"), all Advances that would otherwise be made, converted and/or
continued by Bank of the Affected Type shall be made, converted and/or
continued instead as Base Rate Advances (and, if an event referred to in
Section 2.14 or 2.15 hereof has occurred and Agent so requests by notice to the
Borrower, all Affected Advances then outstanding shall be automatically
converted into Base Rate Advances and, to the extent that Affected Advances are
so made as (or converted into) Base Rate Advances, all payments of





                                       40
<PAGE>   46
principal which would otherwise be applied to such Bank's Affected Advances
shall be applied instead to its Base Rate Advances as determined by Agent.  Any
payment, prepayment or conversion required hereunder which occurs on a day
other than the last day of an Interest Period, shall be subject to the payment
obligations of Section 2.12 hereof.

         2.17    The Facilities.  Notwithstanding any term or provision
contained in any Loan Document and related documentation to the contrary, it is
hereby agreed that in no event shall Chapter 15 of Subtitle 3, Title 79,
Revised Civil Statutes of Texas, 1925, as amended, apply to any Loan Document
or related documentation or the loan transactions provided for hereunder in any
manner.  All payments by Borrower on account of the Notes, an Application, the
L/C Facility and related documentation, or other amounts payable by Borrower
pursuant to the terms of this Agreement shall be made in Dollars and in
immediately available funds in Houston, Harris County, Texas, at the Payment
Office of the Agent not later than 12:00 noon, Houston time, on the day such
payment shall become due, and any payments received after such time shall be
deemed received on the next following Business Day.  In any case where a
payment of principal of or interest on a Loan or a Reimbursement Obligation is
due on a day which is not a Business Day, the Borrower shall be entitled to
delay such payment until the next succeeding Business Day, but interest shall
continue to accrue at the rate then effective under the Notes or with respect
to such Reimbursement Obligation, as applicable, until the payment is, in fact,
made.  Except for Required Payments, which shall be applied as herein provided,
each payment received by the Agent on the Notes or any Letters of Credit
presented for payment, shall be applied first to Reimbursement Obligations,
second to fees, expenses and other like obligations due under this Agreement or
the other Loan Documents, third to accrued, earned and unpaid interest and the
remainder, if any, to principal portions then due.

         2.18    Taxes.

         (a)     Payments Free and Clear.  Any and all payments by the Borrower
under this Agreement or any of the other Loan Documents shall be made free and
clear of and without deduction for any and all present or future taxes, levies,
imposts, deductions, charges or withholdings, and all liabilities with respect
thereto, excluding, in the case of each of the Banks and the Agent, taxes
imposed on its income, and franchise or similar taxes imposed on it, by (i) any
jurisdiction (or political subdivision thereof) of which the Agent or such
Bank, as the case may be, is a citizen or resident or in which such Bank has a
permanent establishment (or is otherwise engaged in the active conduct of its
business through an office or a branch) which is such Bank's Applicable Lending
Office, (ii) the jurisdiction (or any political subdivision thereof) in which
the Agent or such Bank is organized, or (iii) any jurisdiction (or political
subdivision thereof) in which such Bank or the Agent is presently doing
business which taxes are imposed solely as a result of doing business in such
jurisdiction (all such non-excluded taxes, levies, imposts, deductions,
charges, withholdings and liabilities so arising out of payments by the
Borrower being hereinafter referred to as "Taxes").  If the Borrower shall be
required by law to deduct any Taxes from or in respect of any sum payable
hereunder to the Banks or the Agent (i) the sum payable shall be increased by
the amount necessary so that after making all required deductions (including
deductions applicable to additional sums payable under this Section 2.18) such
Bank or the Agent (as the case may be) shall receive an amount equal to the sum
it would have received had no such deductions been made, (ii) the Borrower
shall make





                                       41
<PAGE>   47
such deductions and (iii) the Borrower shall pay the full amount deducted
to the relevant taxing authority or other Governmental Authority in accordance
with applicable law.

         (b)     Other Taxes.  In addition, the Borrower agrees to pay any
present or future stamp or documentary taxes or any other excise or property
taxes, charges or similar levies that arise from any payment made hereunder or
from the execution, delivery or registration of, or otherwise with respect to,
this Agreement, any Assignment and Acceptance or any other Loan Document
(hereinafter referred to as "Other Taxes").

         (c)     Receipts.  Within 30 days after the date of any payment of
Taxes or Other Taxes withheld by the Borrower in respect of any payment to any
of the Banks or the Agent, the Borrower will furnish to the Agent the original
or a certified copy of a receipt evidencing payment thereof.

         (d)     Survival.  Without prejudice to the survival of any other
agreement contained herein, the agreements and obligations contained in this
Section 2.18 shall survive the payment in full of principal and interest
hereunder.

                 ARTICLE III -- REPRESENTATIONS AND WARRANTIES

         The Borrower hereby represents and warrants to each of the Banks as
follows:

         3.01    Legal Existence.  Borrower and each of the Significant
Subsidiaries is a corporation duly organized, validly existing and in good
standing under the laws of the jurisdictions under which they are incorporated,
and each is duly qualified to do business as of the date hereof in all
jurisdictions wherein the property owned or the business transacted by each
would require such qualification, except where the failure to so qualify would
not have a Material Adverse Effect on the Borrower or any of the Significant
Subsidiaries.

         3.02    Corporate Power and Authority to Execute Documents.  Borrower
and each of the Significant Subsidiaries party to any of the Loan Documents has
all requisite corporate power and authority to create, issue, execute, deliver,
carry out and comply with this Agreement and the other Loan Documents to which
each is a party.  The Borrower and each of the Significant Subsidiaries have
all requisite corporate power and authority and all necessary licenses,
permits, franchises and other authorizations to own and operate its property
and to carry on its business as now conducted and as proposed to be conducted,
except where the failure to have such licenses, permits, franchises or other
authorizations would not have a Material Adverse Effect on the Borrower and the
Significant Subsidiaries taken as a whole.

         3.03    Direct Benefit From Loans.  The Borrower and the Significant
Subsidiaries have each received, or, upon its execution thereof, will receive
direct benefit from the making and execution of this Agreement and the other
Loan Documents to which it is a party.  All proceeds of the Revolving Loans
will be used for working capital purposes of the Borrower or by the Borrower
for the benefit of its Subsidiaries.





                                       42
<PAGE>   48
         3.04    Valid, Binding, Enforceable Obligations.  The Borrower and
each of the Significant Subsidiaries have duly and effectively taken all
corporate action requisite for the due creation, execution, issuance, delivery
and performance of this Agreement and all other Loan Documents to which it is a
party, and this Agreement and each of the other Loan Documents to which it is a
party, when executed, will constitute a legally valid and binding obligation of
the Borrower and each of such Significant Subsidiaries, enforceable against
each such Person in accordance with their respective terms except as limited by
bankruptcy, reorganization, moratorium or other similar laws and judicial
decisions affecting the enforcement of creditors' rights generally and by
general equitable principles.

         3.05    No Violation of Charter, By-Laws or Agreements. Neither the
Borrower nor any of the Significant Subsidiaries is in violation of any term of
its certificate of incorporation or articles of incorporation, as appropriate,
or by-laws.  Neither Borrower nor any of its Subsidiaries is in default or
violation of any term of any indenture, mortgage, deed of trust, promissory
note, loan agreement, note agreement or other material agreement including, but
without limitation, any lease, to which it is a party or by which it or any of
its property may be bound or subject, the violation of which would have a
Material Adverse Effect on the Borrower and the Significant Subsidiaries taken
as a whole.

         3.06    No Violation of Laws, Rules or Orders.  Neither the Borrower
nor any of its Subsidiaries is:

                 (i)      in violation of any laws, ordinances, statutes,
         rules, regulations, franchises, certificates, permits or other
         Governmental Requirements to which it is subject, the violation of
         which would have a Material Adverse Effect on the Borrower and the
         Significant Subsidiaries taken as a whole; or

                 (ii)     in default with respect to any judgment, order, writ,
         injunction, decree or demand of any court, arbitrator or governmental
         body which individually or in the aggregate would have a Material
         Adverse Effect on Borrower and the Significant Subsidiaries taken
         as a whole.

         3.07    Loan Documents Do Not Violate Other Documents. Neither the
execution and delivery by the Borrower or any of the Significant Subsidiaries
of this Agreement or any other Loan Document to which it is a party nor the
consummation of the transactions herein and therein contemplated, nor the
performance of, or compliance with, the terms and provisions hereof and
thereof, does or will breach or violate any provision of its certificate of
incorporation or articles of incorporation or bylaws, or any applicable law,
statute, rule or regulation or any judgment, decree, writ, injunction,
franchise, order or permit applicable to the Borrower or any of the Significant
Subsidiaries or their respective assets or properties, or does or will conflict
or be inconsistent with, or does or will result in any breach or default of,
any of the terms, covenants, conditions or provisions of, or constitute a
default under, or result in the creation or imposition of any Lien, security
interest, charge or encumbrance upon any of the property or assets of the
Borrower or any of the





                                       43
<PAGE>   49
Significant Subsidiaries pursuant to the terms of any indenture, mortgage, deed
of trust, loan agreement, or other instrument to which the Borrower or any of
the Significant Subsidiaries is a party or by which the Borrower or any of the
Significant Subsidiaries or any of their respective properties may be bound,
the contravention, conflict, inconsistency, breach or default of which will
have a Material Adverse Effect on Borrower and the Significant Subsidiaries
taken as a whole, or affect their respective abilities to perform, promptly and
fully, their respective obligations hereunder or under any of the other Loan
Documents.

         3.08    Board of Directors Authorization.  The Boards of Directors of
the Borrower and each of the Significant Subsidiaries, acting pursuant to a
duly called and constituted meeting, after proper notice, or pursuant to a
valid and unanimous written consent, has determined that entry into and
performance of this Agreement and each of the other Loan Documents to which any
of the Borrower or any of the Significant  Subsidiaries is a party, directly or
indirectly benefits each of such Persons, and that adequate and fair
consideration has been received by the Borrower and each Significant Subsidiary
to execute and perform this Agreement and each of the other Loan Documents to
which each of such Persons is a party.

         3.09    Financial Statements.  The Financial Statements, which have
been delivered to the Bank, were prepared in accordance with generally accepted
accounting principles, consistently applied, and present fairly in all material
respects the Consolidated financial condition and results of operations of the
Borrower and each of its Subsidiaries as at the date and for the period covered
thereby.  Since March 31, 1994, no Material Adverse Effect has occurred with
respect to the Borrower and its Subsidiaries taken as a whole.

         3.10    No Undisclosed Liabilities.  As of the date hereof, neither
the Borrower nor any of its respective Subsidiaries has any liabilities or
Indebtedness, direct or contingent, except as disclosed in the Financial
Statements or as disclosed to the Banks in Schedule 3.10 attached hereto, and
except for liabilities or Indebtedness which, in the aggregate, do not exceed
$1,000,000.

         3.11    Tax Returns and Payments.  All tax returns required to be
filed by the Borrower or the Significant Subsidiaries in any jurisdiction have
been filed; all taxes, assessments, fees and other governmental charges upon
the Borrower or any of the Significant Subsidiaries and upon their respective
properties, income or franchises, which are due and payable have been paid,
other than those which are being contested in good faith and as to which the
Borrower or the Significant Subsidiaries, as required by GAAP, have established
adequate reserves determined in accordance with GAAP, except where the failure
to file such return or pay such taxes, assessments, fees and other governmental
charges or record adequate reserves (i) would not have a material adverse
effect on the condition, financial or otherwise, of the Borrower and the
Significant Subsidiaries taken as a whole, and (ii) does not involve unpaid
amounts in the aggregate, with respect to the Borrower and its Subsidiaries, in
excess of $1,000,000.

         3.12    ERISA.  Except as disclosed on Schedule 3.12, each Plan of the
Borrower and its Subsidiaries satisfies the minimum funding standards under all
Laws applicable thereto, no ERISA Event has occurred with respect to any such
Plan and no such Plan has an accumulated funding deficiency thereunder.
Neither the Borrower nor any of its Subsidiaries has incurred any material
liability to the PBGC with respect to any Plan.  Neither the Borrower nor any
of its Subsidiaries has participated in any prohibited transactions with
respect to any Plan or trust





                                       44
<PAGE>   50
created thereunder, and the consummation of the transactions contemplated
hereby, and by the other Loan Documents, will not involve any Prohibited
Transactions.  Neither the Borrower nor any of its Subsidiaries is a
participant in, or obligated to contribute to, a Multiemployer Plan.

         3.13    Environmental Laws.  None of the real property in which the
Borrower or any of its subsidiaries has an interest (whether leased or owned)
or the operations currently conducted thereon by such Person or, to the
knowledge of the Borrower, conducted by any current or prior owner or operator
thereof, (a) violates or has violated any applicable Environmental Laws the
violation of which could reasonably be expected to result in a Material Adverse
Effect on the Borrower and the Significant Subsidiaries taken as a whole, or
result in costs not otherwise covered by insurance from a Person that is not an
Affiliate of the insured, penalties, fines or damages payable by the Borrower
or any of its Subsidiaries in an aggregate amount in excess of $10,000,000 or
more, or (b) subject, except as disclosed in writing to the Banks or the in
Borrower's Form 10-K for the period ended December 31, 1993, to any pending or
threatened investigation or proceedings by any Tribunal or to remedial
obligations under any Environmental Law.  All licenses have been obtained or
filed that are required under any Environmental Law in connection with the use
by the Borrower or any Significant Subsidiary of such real property (including
without limitation past or present treatment, storage, disposal and release of
any Hazardous Materials into the environment).  No Hazardous Materials have
been disposed of or otherwise released by Borrower or any of its Subsidiaries
on or to any real property, lake, ocean, bay, sea or river, in which any
operations of the Borrower or any of its Subsidiaries are conducted, except in
compliance in all material respects with Environmental Laws.  None of the
Borrower or any of its Subsidiaries has any liability which would be material
to the Borrower and its Subsidiaries taken as a whole, with respect to any
release of any Hazardous Materials into the environment.  The use which each of
the Borrower and its Subsidiaries makes or intends to make of their respective
properties that consists of interests in real property (whether leased or
owned) on which any of its operations are conducted will not result in the
unlawful or unauthorized disposal or other release of any Hazardous Materials,
except in compliance in all material respects with applicable Environmental
Laws.

         3.14    Subsidiaries.  Borrower has no Subsidiaries except as listed
on Schedule 3.14.  Each of the Significant Subsidiaries is a Wholly-Owned
Subsidiary of the Borrower.  Schedule 3.14 contains a complete and accurate
listing of each Significant Subsidiary of the Borrower showing (i) its complete
name, (ii) its jurisdictional organization, (iii) its street and mailing
address, which is its principal place of business and executive office, and
(iv) all interests in such Significant Subsidiary owned by the Borrower or any
of its Subsidiaries.  None of the Significant Subsidiaries has issued or
outstanding any warrants, options, rights or other obligations to issue or
purchase any shares of their respective capital stock or other securities.  The
outstanding shares of capital stock of each of the Significant Subsidiaries
have been duly authorized and validly issued and are fully paid and
nonassessable.

         3.15    Not a Secured Purpose Credit.  None of the proceeds of any
Loan will be used for the purpose of purchasing or carrying any "margin stock"
(within the meaning of Regulation U of the Board of Governors of the Federal
Reserve System) where such Loan will be secured by margin stock, directly or
indirectly, or for the purpose of extending credit secured by margin stock,
directly or indirectly, to any Person or entity for the purpose of purchasing
or carrying





                                       45
<PAGE>   51
any such margin stock or for the purpose of reducing or retiring any
indebtedness which was originally incurred to purchase or carry a margin stock
or for any other purpose which might constitute this transaction (or any aspect
hereof) a "purpose credit" secured by margin stock, directly or indirectly,
within the meaning of said Regulation U, as now in effect or as hereafter
amended.

         3.16    Investments and Obligations.  As of the date hereof, neither
the Borrower nor any of the Significant Subsidiaries has made any investments
in, advances to, or  guaranties of the obligations of, any Person, except as
disclosed in the Borrower's report on Form 8-K filed May 6, 1994, the report on
Form 10-K for the year ended December 31, 1993 or in the Borrower's report on
Form 10-Q for the fiscal quarter ended March 31, 1994.

         3.17    Consents Not Required.  Except for those consents which have
already been obtained, no consent of any other Person and no consent, license,
permit, approval, or authorization of, exemption by, or registration or
declaration with, any Tribunal is required in connection with the execution,
delivery, performance, validity,  or enforceability of this Agreement or any of
the Loan Documents.

         3.18    Litigation Pending.  Except for the Litigation disclosed on
the Borrower's report on Form 10-K for the year ended December 31, 1993, or in
the Borrower's report on Form 10-Q for the fiscal quarter ended March 31, 1994,
there is no Litigation pending or, to the knowledge of the Borrower, overtly
threatened against the Borrower or any of the Significant Subsidiaries which,
if adversely determined, would have a Material Adverse Effect on the Borrower
and the Significant Subsidiaries taken as a whole.

         3.19    Material Fact Representations.  Neither the Loan Documents nor
any other agreement, document, certificate, or written statement furnished to
the Banks by or on behalf of the Borrower or any of the Significant
Subsidiaries in connection with the transactions contemplated in any of the
Loan Documents contains any untrue statement of material fact.  As of the date
of this Agreement, there are no material facts or conditions relating to the
making of the Loans, or the establishment of the L/C Facility, and/or the
financial condition and business of the Borrower or any of the Significant
Subsidiaries which have not been fully disclosed, in writing, to the Banks.

         3.20    Borrower's Status.  Neither Borrower nor any of its
Subsidiaries is an "investment company" or a company "controlled by an
investment company" within the meaning of the Investment Company Act of 1940,
as amended.  Neither the Borrower nor any of its Subsidiaries is a "holding
company" or a "subsidiary company" of a "holding company" or an "affiliate" of
a "holding company" or a "subsidiary company" of a "holding company", or a
"public utility" within the meaning of the Public Utility Holding Company Act
of 1935, as amended.

                      ARTICLE IV -- AFFIRMATIVE COVENANTS

         So long as any of the Notes remain unpaid, any Letters of Credit
remain outstanding or the Banks have any commitment hereunder to make Loans or
any Obligations hereunder or in connection herewith remain unpaid, the Borrower
covenants, that it will do, or where applicable cause to be done, the
following:





                                       46
<PAGE>   52
         4.01    Reporting Obligations.  The Borrower will furnish to the Agent
three copies of each of the following (and all financial statements furnished
under this Subsection 4.01 shall be prepared in accordance with GAAP
consistently applied throughout the periods involved):

         (a)     As soon as available, but in any event within 120 days after
the end of each fiscal year of the Borrower, (i) a Loan Formula Certificate,
(ii) a Quarterly Compliance Certificate for the Borrower's fourth fiscal
quarter, and (iii) a copy of the Consolidated financial report of the Borrower,
including the Consolidated and consolidating balance sheet of the Borrower as
of the close of such fiscal year, the related Consolidated and consolidating
statement of income and the related Consolidated and consolidating statement of
changes in cash flows of the Borrower for such fiscal year, setting forth in
comparative form the figures for the preceding fiscal year, all such
Consolidated financial statements to be accompanied by an unqualified opinion
of independent certified public accountants selected by the Borrower (from
among the "big six" national accounting firms), that such financial statements
fairly present in all material respects the financial condition and results of
operations of the Borrower as of the close of the period covered by the report;

         (b)     Within three Business Days of delivery thereof to the
Securities and Exchange Commission, copies of all filings by the Borrower
therewith (including, without limitation, all filings on Form 10-K, Form 10-Q,
Form 8-K, all prospectuses, all amendments to the foregoing and all proxy
materials filed therewith);

         (c)     As soon as available, but in any event within 60 days after
the end of each fiscal quarter of each fiscal year of the Borrower (other than
the fourth quarter of each such fiscal year), (i) a Loan Formula Certificate,
(ii) a Quarterly Compliance Certificate, and (iii) a Consolidated balance sheet
as at the close of such quarter, a Consolidated statement of income and a
Consolidated statement of changes in cash flows of the Borrower for such
quarter and for the period ending with such quarter, setting forth in
comparative form the corresponding figures for the corresponding quarter and
period of the preceding fiscal year, all certified by an Authorized
Representative of the Borrower as fairly presenting in all material respects
the financial position, results of operations and changes in cash flows of the
Borrower and its Subsidiaries as at the date thereof and for the period then
ending;

         (d)     As soon as available, but in any event within 30 days after
the end of each calendar month in each fiscal year of the Borrower beginning
with the calendar month ended April 30, 1994, an aging schedule of accounts
receivable of the Borrower and the Significant Subsidiaries as of the last day
of the preceding month, in form reasonably satisfactory to the Banks, and
setting forth all information necessary to determine (i) whether the accounts
of the Borrower and the Significant Subsidiaries are Eligible Accounts, (ii)
whether the account debtors thereon are Eligible Account Debtors, and (iii) the
total amount of the Borrowing Base, all certified by an Authorized
Representative of the Borrower, as presenting fairly in all material respects
the Borrower's and the Significant Subsidiaries' aging schedule of accounts
receivable, the financial position as at the date thereof and for the period
then ended and the other information set forth therein;





                                       47
<PAGE>   53
         (e)     Promptly, but in any event within five Business Days, (i)
after becoming aware of a Default or Event of Default, the Borrower shall give
a verbal notification to the Agent specifying the nature and period of
existence thereof and what action it is taking or proposes to take with respect
thereto and, immediately thereafter, a written confirmation to the Agent of
such matters, and (ii) after the release thereof, the Borrower shall deliver to
Agent a copy of all press releases;

         (f)     Promptly, but in any event within five Business Days, after
becoming aware that any Person has given notice of, or taken any other action
with respect to, a claimed default under any indenture, mortgage, deed of
trust, promissory note, loan agreement, note agreement, operating or joint
venture agreement or any other material agreement or undertaking, to which the
Borrower or any of the Significant Subsidiaries is a party and pursuant to
which any of them are or, if the obligation evidenced or represented by any
such agreement or undertaking could (as a result of such default) be
accelerated, could be obligated in an amount of at least $1,000,000, the
Borrower will give a verbal notification to the Bank specifying the notice
given or action taken by such Person and the nature of the claimed default and
what action the Borrower and the applicable Significant Subsidiary is taking or
proposes to take with respect thereto and, immediately thereafter, a written
confirmation to the Agent of such matters;

         (g)     Promptly, but in any event within ten Business Days, after
becoming aware of any action, suit or proceeding pending or overtly threatened
against or affecting the Borrower or any Significant Subsidiary before any
Tribunal which, if adversely determined (i) could individually or in the
aggregate, result in a monetary judgment of $1,000,000 or more not otherwise
fully covered by insurance; provided, that claims for personal injury or death
asserted individually or in the aggregate by Jones Act seamen (including
related general maritime law claims such as allegations of unseaworthiness or
demands for maintenance and cure) or employees of Borrower or its Subsidiaries,
of up to $1,250,000 at any one time outstanding, need not be reported to Agent
pursuant to this Section 4.01(g), or (ii) if other than a monetary judgment is
requested, whether in the alternative or in addition to the monetary remedies
therein sought, could materially and adversely affect the property, business,
operation, or condition, financial or otherwise, of the Borrower and any of the
Significant Subsidiaries taken as a whole, the Borrower will give a verbal
notification to the Agent specifying the nature thereof, whether the alleged
liability therein is covered by insurance then in effect and, if so covered,
the monetary coverage thereof, and what action the Borrower or any of the
Significant Subsidiaries is taking or proposes to take with respect thereto and
immediately thereafter, a written confirmation to the Agent of such matters;

         (h)     Promptly, but in any event within ten Business Days, after
becoming aware of the occurrence of any event or circumstance which more than
likely would have a Material Adverse Effect on the Borrower and the Significant
Subsidiaries taken as a whole, give a verbal notification to the Agent
specifying such event or occurrence and, immediately thereafter, a written
confirmation to the Agent of such matters;

         (i)     Promptly after the filing thereof with the United States
Secretary of Labor, the Internal Revenue Service or the PBGC by the Borrower
or any of the Significant Subsidiaries, the Borrower will furnish to the Agent
and the Banks copies of each annual and other reports





                                       48
<PAGE>   54
with respect to each Plan or any trust created thereunder, and (ii) immediately
upon becoming aware of the occurrence of (A) the termination or requested or
intended termination of a Plan, or (B) any event that would be a "reportable
event" as such term is defined in Section 4043 of ERISA, or of any Prohibited
Transaction, in connection with, or if it were applicable to, any Plan or any
trust created thereunder, the Borrower will communicate a verbal notification
to the Agent specifying the nature thereof, and, with respect thereto, and,
when known, any action taken by the Internal Revenue Service and immediately
thereafter, a written confirmation to the Agent of such matters;

         (j)     Promptly, but no later than 15 days, after the date that the
Borrower or any of the Significant Subsidiaries changes its name (or uses any
name other than previously disclosed in writing to the Agent), or the address
and/or location of its chief executive office or principal place of business or
the place where it keeps its books and records or its inventory, written
notification to the Agent of such changes and all relevant information with
regard thereto;

         (k)     Promptly, as required pursuant to Section 2.03, the Loan
Request Forms and related Loan Formula Certificates;

         (l)     Promptly, but in any event prior to the last day of each
fiscal year of the Borrower, (i) Consolidated operating budget, including,
without limitation, a projected income statement, balance sheet and Capital
Expenditures budget, for the Borrower and its Subsidiaries for the next
succeeding fiscal year thereof, setting forth all material projected cash flows
for such period and the assumptions used in preparing such budget, and (ii) a
Consolidated Capital Expenditures budget for the Borrower and its Subsidiaries
for the next succeeding fiscal year thereof, setting forth all projected
capital expenditures for such period and the assumptions used in preparing such
budget; and

         (m)     Within ten Business Days (or, if because of the nature of the
request a longer period of time is required, as promptly as reasonably
possible) after a reasonable request by the Agent, all other reports and
information (or true and correct copies thereof) regarding the operation,
financial and business condition of the Borrower and its Subsidiaries (or all
of them).  All writings heretofore or hereafter exhibited or delivered to the
Bank by or on behalf of the Borrower or any of the Significant Subsidiaries are
and will be genuine and what they purport to be.

         4.02    Payment of Taxes and Claims.  The Borrower will, and will
cause each of the Significant Subsidiaries to pay and discharge, before they
become delinquent:

                 (a)      all taxes, assessments and governmental charges or
         levies imposed upon any of them or upon their respective income or
         property or any part thereof; and

                 (b)      all claims of any kind (including claims for labor,
         materials, supplies and rent) which, if unpaid, might result in the
         creation of a Lien upon any of their respective properties;





                                       49
<PAGE>   55
provided, that items of the foregoing description need not be paid (i) if such
failure to pay any of same could not have a Material Adverse Effect on Borrower
or any of the Significant Subsidiaries, or (ii) if (A) being contested in good
faith by appropriate proceedings diligently conducted if such proceedings do
not involve any likelihood of the sale, forfeiture or loss of any such property
or any interest therein while such proceedings are pending, and (B) provided
further that book reserves adequate under GAAP shall have been established
generally therefor and (C) provided further that the owing Person's title to,
and its right to use, its property is not materially adversely affected
thereby.

         4.03    Maintenance of Existence, Property and Records. The Borrower
will, and will cause each of the Significant Subsidiaries to:

                 (a)      maintain its existence, rights and franchises as
         necessary to conduct properly its business, and continue to be or
         become (as the case may be) duly authorized and qualified to transact
         business in each jurisdiction wherein the property owned or the
         business transacted by it makes such qualification necessary, except
         where the failure to maintain such authorization or qualification, in
         any jurisdiction, or in all jurisdictions in the aggregate, does not
         have a Material Adverse Effect on the Borrower and the Significant
         Subsidiaries taken as a whole;

                 (b)      maintain property owned, leased or otherwise used by
         it in good and workable condition at all times (normal wear and tear
         excepted) and make all repairs, replacements, additions, betterments
         and improvements to such property as are necessary or desirable to
         continue its business as then normally conducted; and

                 (c)      maintain and keep books of records and accounts, all
         in accordance with GAAP, of all dealings and transactions in relation
         to its business and activity.

         4.04    Compliance With Laws.  The Borrower will, and will cause each
of its Subsidiaries to, observe and comply with:

                 (a)      all laws, statutes, codes, acts, ordinances, rules,
         regulations, directions and requirements of all Federal, state,
         county, municipal and other governments, departments, commissions,
         boards, courts, authorities, officials and officers, domestic and
         foreign, applicable to it and where the failure to observe or comply
         would have a Material Adverse Effect on the Borrower and the
         Significant Subsidiaries taken as a whole; and

                 (b)      all orders, judgments, decrees, injunctions,
         certificates, franchises, permits, licenses and authorizations of all
         Federal, state, county, municipal and other governments, departments,
         commissions, boards, courts, authorities, officials and officers,
         domestic and foreign, applicable to it and where the failure to
         observe or comply would have a Material Adverse Effect on the Borrower
         and the Significant Subsidiaries taken as a whole, and against which
         it shall maintain such reserves as are appropriate under GAAP.





                                       50
<PAGE>   56
         4.05    Cure of Defects in Loan Documents.  The Borrower will, and
will cause each of the Significant Subsidiaries, to cure promptly and cause to
be cured promptly any defects in the creation, issuance, execution and delivery
of this Agreement and the other Loan Documents; and upon request of the Agent
and at the Borrower's expense, the Borrower will promptly execute and deliver,
and cause to be executed and delivered, to the Banks, all such additional
documents, agreements and/or instruments in compliance with or accomplishment
of the covenants and agreements of this Agreement and the other Loan Documents,
and/or to create, perfect, preserve, extend and/or maintain any and all Liens
created pursuant to the Loan Documents as valid and perfected Liens in favor of
the Banks to secure the Obligations, all as reasonably requested by the Agent.

         4.06    Payment of Expenses.  The Borrower will pay all reasonable
out-of-pocket costs, expenses, legal fees and related disbursements incurred by
or on behalf of the Agent in connection with the preparation, review,
negotiation and administration of, this Agreement and the other Loan Documents
or in connection herewith or therewith, including, without limitation, any and
all amendments, supplements, modifications, extensions, restatements, waivers
and consents.  In the event that this Agreement or any of the Loan Documents
must be renegotiated or restructured after the date hereof following the
occurrence of an Event of Default, Borrower will pay all reasonable
out-of-pocket costs, expenses, legal fees and related disbursements incurred by
or on behalf of the Agent or any of the Banks in connection therewith.  Upon
request, the Borrower will reimburse promptly the Agent and the Banks for all
reasonable amounts expended, advanced or incurred by the Agent or the Banks to
satisfy or collect any obligation of the Borrower, or enforce any of the Banks'
rights against any Person, arising under or in connection with this Agreement
or any other Loan Document (whether or not any legal proceeding is instituted),
which amounts will include, but not be limited to, all court costs, reasonable
attorneys' fees, fees of auditors and accountants, and investigation expenses
reasonably incurred by or on behalf of the Agent or the Banks to third parties
in connection with any such matters, together with interest at a per annum rate
equal to the lesser of (a) the Default Rate and (b) the Maximum Rate, on each
such amount expended by the Agent or the Banks, with interest on unpaid amounts
to accrue commencing ten days after written demand for payment of such amount
is made by the Agent or the Banks, until the date it is repaid to the Agent and
to the Banks; and the foregoing obligations of the Borrower shall survive the
payment, in full, of all amounts owed on the Notes and of all Reimbursement
Obligations.  All payments of amounts owing under this Section 4.06 shall be
applied first to accrued, unpaid interest, with the balance, if any, being
applied to principal.

         4.07    Inspection of Books, Property and Affairs.  At any and all
reasonable times, upon request from the Agent, the Borrower will, and will
cause each of its Subsidiaries, to permit any officer, employee, agent or
representative of, or designated by, the Agent or any of the Banks:

                 (a)      to examine, at the Banks' cost and expense, its books
         of accounts, records, reports and other papers (and to make copies and
         extracts therefrom);

                 (b)      to inspect, at the Banks' cost and expense, all of
         its property and all related information and reports; and





                                       51
<PAGE>   57
                 (c)      to discuss its business and affairs with its
         officers, auditors and its independent certified public accountants.

         4.08    Insurance.  The Borrower and each of the Significant
Subsidiaries now maintains, and the Borrower will and will cause each of the
Significant Subsidiaries to continue to maintain with financially sound and
reputable insurers, insurance with respect to their respective properties and
businesses against such liabilities, casualties, risks and contingencies and in
such types and amounts as is customary in the case of corporations engaged in
the same or similar business or having similar property and assets similarly
situated, including without limitation, insurance with respect to fire,
tornado, casualty, other hazards normally insured, liability on account of
damages to Persons or property, products liability coverage, public liability,
employee fidelity coverage, and worker's compensation, but in no event shall
the foregoing provisions require the Borrower or any of the Significant
Subsidiaries to maintain insurance coverage that is neither customary to
Persons (or their operations) engaged in the same or similar businesses or
operations or having property and assets similarly situated nor generally
available to such businesses for comparable operations, nor, in the reasonable
business judgment of the Borrower or any of the Significant Subsidiaries,
prohibitive in expense and/or coverage requirements for its issuance; provided,
however, in each of the foregoing instances in which insurance may not be in
effect, the Borrower will and will cause each of the Significant Subsidiaries
to take all reasonable steps, actions and precautions and, where appropriate,
provide for such reserves and other contingencies, to minimize the effect of
any casualty, liability or property loss that could foreseeably occur or result
therefrom, which would be of any material consequence; and the Borrower and
each or any of the Significant Subsidiaries (as the Agent may request) will
within 60 days after the end of each fiscal year of the Borrower, furnish or
cause to be furnished to the Agent from time to time a summary of the insurance
coverage of the Borrower or any of the Significant Subsidiaries in form,
substance and detail reasonably satisfactory to the Agent and, upon request by
the Agent, copies of applicable policies, together with evidence of the payment
of all premiums therefor.

         4.09    Payment of Fees.  Borrower will pay to the Agent on a timely
basis all Facility Fees, Commitment Fees and other fees required hereunder.

         4.10    Cash Management.  In connection with the Loans, Borrower will
and will cause the Significant Subsidiaries, which generate Eligible Accounts
constituting a part of the Borrowing Base, other than Foreign Subsidiaries,
doing business in the United States to use the lockbox facilities of Agent, to
which Borrower and such Subsidiaries will deposit and maintain all proceeds of
their respective accounts.

         4.11    Guarantees and Notes.  If, at any time after the date hereof,
there exists any Significant Subsidiary (i) that is not a Foreign Subsidiary,
then the Borrower shall cause each such Person (except for Triton) to execute
and deliver to the Agent (a) a guaranty in the form of the Guaranty and (b) a
written opinion of counsel for each such Subsidiary in form and substance
satisfactory to the Agent and its counsel, and (ii) that is also a Foreign
Subsidiary, such Foreign Subsidiary (except for Noble Drilling (Canada) Ltd.)
shall execute and deliver to Agent (a) an Intercompany Revolving Credit Note to
evidence loans made by Borrower thereto





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<PAGE>   58
from time to time, and (b) a written opinion of counsel for each such
Subsidiary in form and substance satisfactory to the Agent and its counsel.

                        ARTICLE V -- NEGATIVE COVENANTS

         So long as any of the Notes remains unpaid, any Letters of Credit
remain outstanding or the Banks have any commitment to make any Loans, or any
Obligations hereunder or in connection herewith remain unpaid, the Borrower
covenants with the Banks:

         5.01    Limitations on Funded Debt.  The Borrower will not, and will
not permit any of its Subsidiaries (other than a Non- Recourse Subsidiary), to,
directly or indirectly, create, incur, assume, suffer to exist, guarantee or in
any manner become or be liable for or permit to be outstanding any Funded Debt,
unless (i) no Event of Default has occurred and is continuing, and (ii)
immediately after the date of such transaction and after giving effect to the
creation, incurrence, assumption, existence or guaranty thereof or liability
therefor, (a) no Event of Default would arise as a result of such creation,
incurrence, assumption, existence or guaranty, and (b) without limiting the
generality of the foregoing, no violation of Section 5.07 hereof exists or
would result therefrom.

         5.02    Limitations on Liens.  The Borrower will not, and will not
permit any of its Subsidiaries to, directly or indirectly, create, incur,
assume or suffer to exist any Liens on or with respect to any Property of the
Borrower or such Subsidiary or any interest therein or any income or profits
therefrom, whether owned at the date hereof or hereafter acquired, other than
Permitted Liens.

         5.03    Restricted Payments.  (a) The Borrower will not, and will not
permit any of its Subsidiaries to, make any Restricted Payment if at the time
thereof, and after giving effect thereto (the amount of any such payment to be
made other than in cash to be determined by the board of directors of the
Person making such payment, which determination shall be conclusive and
evidenced by resolutions of such board of directors), (i) any Event of Default
shall have occurred and be continuing or would result therefrom, (ii) the
incurrence of at least $1.00 of additional Funded Debt would not be permitted
under Section 5.01 hereof, and (iii) the effectuation of the Restricted Payment
would, after giving effect to such Restricted Payment, violate Section 5.06
hereof.

         (b)     The provisions of this Section 5.03 shall not prevent the
Borrower or any Subsidiary from paying a dividend on the capital stock thereof
within 60 days after the declaration thereof if, on the date of declaration,
the Borrower or such Subsidiary could have paid such dividend in compliance
with the other provisions of this Section 5.03 and the other provisions of this
Agreement.





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<PAGE>   59
         5.04    ERISA Limits.  The Borrower will not at any time permit any
Plan to:

                 (a)      engage in any "prohibited transaction" as such term
         is defined in Section 4975 of the Internal Revenue Code of 1986, as
         amended, involving any amount in excess of $250,000;

                 (b)      incur any "accumulated funding deficiency" as such
         term is defined in Section 302 of ERISA; or

                 (c)      terminate any such Plan in a manner which could
         result in the imposition of a Lien on the property of any of the
         Borrower or any of the Significant Subsidiaries pursuant to Section
         4068 of ERISA.

Furthermore, Borrower will not and will not permit any of the Significant
Subsidiaries to participate in or become obligated to contribute to any
Multiemployer Plan.
         
         5.05    Coverage Ratios.  (a)  The Borrower will not as of the last
day of each (three month) fiscal quarter of the Borrower permit the Borrower's
Special Purpose Fixed Charge Coverage Ratio to be less than 1.1 to 1.0;
provided, however, that for each of the Borrower's (three month) fiscal
quarters ended June 30, 1994, and September 30, 1994, Consolidated EBITDA and
Special Purpose Fixed Charges shall be calculated based solely on the
cumulative financial information for the Borrower's 1994 fiscal quarters then
ended, without regard to and as if there were no business, financial
information or results of operations for the Borrower for 1993.

         (b)  The Borrower will not as of the last day of each (three month)
fiscal quarter of the Borrower permit the Borrower's Fixed Charge Coverage
Ratio to be less than 1.75 to 1.0; provided, however, that for each of the
Borrower's (three month) fiscal quarters ended June 30, 1994, and September 30,
1994, Consolidated EBITDA and Consolidated Fixed Charges shall be calculated
based solely on the cumulative financial information for the Borrower's 1994
fiscal quarters then ended, without regard to and as if there were no business,
financial information or results of operations for the Borrower for 1993.

         5.06    Tangible Net Worth.  The Borrower will not, as of the last day
of each fiscal quarter of the Borrower, allow its Tangible Net Worth to be less
than the sum of (i) $280,000,000, plus (ii) 50% of any positive Consolidated
Net Income computed on a cumulative basis for the period beginning April 30,
1994 and ending on the last day of the fiscal quarter immediately preceding the
date of any determination (no negative adjustment will be made in the event
Consolidated Net Income is a deficit figure for any fiscal period) plus (iii)
85% of the aggregate amount of net noncash proceeds, and 100% of the net cash
proceeds, to the Borrower from the issuance or sale after April 30, 1994, and
determined as of the last day of each fiscal quarter subsequent to March 31,
1994, of (x) shares of common stock of the Borrower or warrants, rights or
options to purchase or acquire shares, of its common stock and (y) shares of
Preferred Stock of the Borrower; provided, that the foregoing 85% rate shall
increase to 100% at such time as the aggregate of all net noncash proceeds from
the sale by





                                       54
<PAGE>   60
Borrower of its common stock, or warrants, rights or options to purchase or
acquire such common stock, exceeds $300,000,000.

         5.07    Leverage.  The Borrower will not, as of the last day of each
(three month) fiscal quarter thereof, allow its Debt to Capital Ratio to exceed
.35.

         5.08    Limitations on Investments.  The Borrower will not and will
not permit any of its Consolidated Subsidiaries to make nor permit to remain
outstanding any Investments except for (i) Permitted Investments, and (ii)
mergers and acquisitions permitted under Section 5.10 hereof.

         5.09    Subsidiary Stock Issuances, Charter Documents and Business
Termination.

         (a) The Borrower will not permit any of the Significant Subsidiaries
to issue, sell or commit to issue or sell any shares of its capital stock of
any class, or other equity or investment security, except for qualifying shares
issued to members of the boards of directors to satisfy a statutory
qualification for service as a director.

         (b)     The Borrower will not and will not permit any of the
Significant Subsidiaries to (i) amend or otherwise modify their respective
corporate charters or otherwise change their respective corporate structures in
any manner which will have a material adverse effect on their respective
condition, financial or otherwise, or which will have a material adverse effect
upon their respective abilities to perform, promptly and fully, their
respective obligations hereunder or under any of the other Loan Documents, or
(ii) take any action with a view toward its dissolution, liquidation or
termination, or, in fact, dissolve, liquidate or terminate its existence.

         5.10    Mergers and Acquisitions.  The Borrower will not and will not
permit any of the Significant Subsidiaries to, form a Subsidiary (except upon
compliance with Section 4.11 hereof with respect to such newly formed
Subsidiary), nor consolidate with or merge into, or acquire any Person (either
all or substantially all of its assets or all of its capital stock) or permit
any Person to consolidate with or merge into, or acquire it, unless, in regard
to any and all of the foregoing and so long as no Default or Event of Default
then exists, the Borrower is the surviving or acquiring party, as the case may
be, or if a Significant Subsidiary is a party to such merger and the Borrower
is not, then the Significant Subsidiary is the surviving or acquiring party, as
the case may be, the Agent is promptly notified in writing, at least thirty
days in advance, of such transaction, such transaction does not materially and
adversely affect the condition, financial, business or otherwise, of the
Borrower and the Significant Subsidiaries taken as a whole, and prior to any
such transaction, the Borrower shall execute and cause to be executed such
additional agreements or guaranties as the Agent may reasonably request to
conform with the provisions hereof and the transactions contemplated under this
Agreement and the other Loan Documents.

         5.11    Changes in Accounting Methods.  The Borrower will not, and
will not permit any of its Consolidated Subsidiaries to, make any material
change in their respective present accounting methods, including, without
limiting the generality of the foregoing, any change which could affect the
calculation of any financial covenants or terms herein including the Fixed
Charge Coverage Ratio, the Tangible Net Worth, the Special Purpose Fixed Charge
Coverage





                                       55
<PAGE>   61
Ratio and the Debt to Capital Ratio, or change its fiscal year ending date from
December 31, unless such changes are required for conformity with GAAP or by
Regulation S-X as promulgated by the Securities and Exchange Commission and, in
such event, the Borrower will give prior written notice of each such change to
the Agent.

         5.12    Changes in Business or Assets.  The Borrower will not and will
not permit any of the Significant Subsidiaries to engage in, or use any of
their respective properties in, any business other than (i) all aspects of
domestic and international offshore contract oil and gas drilling, including
without limitation, consulting, managing, well-site supervising, turnkey
drilling services, production management services, remote logistics,
engineering services and the ownership and operation of drilling facilities and
equipment, (ii) the ownership of interests in oil and gas properties, provided
that such ownership shall not constitute a significant part of the total assets
of Borrower and its Consolidated Subsidiaries taken as a whole, (iii) the
manufacture and sale or lease of drilling rigs to the energy industry, (iv) the
ownership and acquisition of properties or businesses in connection with the
foregoing and (v) any of their or their Subsidiaries' respective businesses as
now conducted, or the use of any of their or their Subsidiaries' respective
properties as now used.

         5.13    Discounting of Receivables.  The Borrower will not and will
not permit the Significant Subsidiaries, except to minimize losses or bona fide
debts previously contracted, to grant liens upon or security interests in, or
to discount or sell with recourse, or sell for less than the greater of the
face or market value thereof, a portion of its notes receivable, accounts
receivable, contract receivables or any other receivables owed to it.

         5.14    Transactions with Affiliates.  The Borrower will not, and will
not permit any of its Subsidiaries to, directly or indirectly, enter into or
permit to exist any transaction or series of related transactions (including,
but not limited to, the purchase, sale, lease or exchange of property or
assets, the making of any Investment, the giving of any guarantee or the
rendering of any service) with any Affiliate of the Borrower other than the
Borrower or a Wholly-Owned Subsidiary, unless such transaction or series of
related transactions is on terms no less favorable to the Borrower or such
Subsidiary than those that could be obtained in a comparable arm's length
transaction with a Person that is not such an Affiliate.

         5.15    Limitation on Subsidiary Indebtedness and Preferred Stock.
The Borrower will not permit any Subsidiary thereof to, directly or indirectly,
create, incur, assume, guarantee or otherwise become liable with respect to the
payment of (collectively, "incur"), any Indebtedness or to issue or suffer to
exist any Preferred Stock, other than:

                 (i)      Permitted Subsidiary Indebtedness;

                 (ii)     Indebtedness of a Subsidiary of Borrower which
         represents the assumption by such Subsidiary of Indebtedness (other
         than Non-Recourse Indebtedness) of another Subsidiary of Borrower in
         connection with a merger of such Subsidiaries, provided that no
         Subsidiary of Borrower or any successor (by way of merger) thereto
         existing on June 16, 1994, shall assume or otherwise incur any
         Indebtedness of an entity which is





                                       56
<PAGE>   62
         not a Subsidiary of Borrower on June 16, 1994, except to the extent
         that such Subsidiary would be permitted to incur such Indebtedness
         under this Agreement;

                 (iii)    Indebtedness or Preferred Stock of any Person
         existing at the time such Person becomes a Subsidiary of Borrower;
         provided, that such Indebtedness was not incurred in anticipation of
         such corporation becoming a Subsidiary of Borrower and would otherwise
         be permitted pursuant to Section 5.05 or Section 5.07;

                 (iv)     Indebtedness or Preferred Stock issued to and held by
         the Borrower or a Wholly-Owned Subsidiary other than a Non-Recourse
         Subsidiary, so long as the transfer of such Indebtedness or Preferred
         Stock to a Person other than the Borrower or any Wholly-Owned
         Subsidiary would be deemed to constitute the issuance of such
         Indebtedness or Preferred Stock by the issuer thereof;

                 (v)      Indebtedness or Preferred Stock issued in exchange
         for, or the proceeds of which are used to refinance, repurchase or
         redeem, Indebtedness or Preferred Stock described in clause (iii) of
         this Section 5.15 or securing Indebtedness outstanding under the
         Indenture (the "Retired Indebtedness or Stock"), provided that the
         Indebtedness or the Preferred Stock so issued has (A) a principal
         amount or liquidation value, as the case may be, not in excess of the
         principal amount or liquidation value of the Retired Indebtedness or
         Stock, (B) a final redemption date later than the stated maturity or
         final redemption date (if any) of the Retired Indebtedness or Stock
         and (C) an Average Life at the time of issuance of such Indebtedness
         or Preferred Stock that is greater than the Average Life of the
         Retired Indebtedness or Stock; or

                 (vi)     Indebtedness or preferred stock of a Subsidiary of
         Borrower, which, when combined with (A) the aggregate amount of all
         other outstanding Indebtedness of the Subsidiaries of Borrower plus
         the aggregate liquidation value of all preferred stock of any
         Subsidiary of Borrower, in either case excluding any Non-Recourse
         Subsidiary (other than Indebtedness secured by Liens described under
         clause (ix) and (xvii) of the definition of "Permitted Liens"),plus
         (B) the aggregate amount of all Indebtedness of the Borrower secured
         by Liens (other than of the type described in clauses (ix), (xiv) and
         (xvii) of the definition of "Permitted Liens"),plus (C) the aggregate
         amount of all Capital Lease Obligations of the Borrower and its
         Subsidiaries shall not exceed 10% of the Borrower's Consolidated Net
         Tangible Assets.

                 "Indenture" means the Indenture dated as of October 1, 1993,
between the Borrower and Texas Commerce Bank National Association as trustee,
and covering the 9 1/4% Senior Notes due 2003.

         5.16    Loan Proceeds.  The Borrower will not lend or advance any
proceeds of any Loan hereunder to any Subsidiary thereof which has neither
executed the Guaranty nor an Intercompany Revolving Credit Note which has been
pledged and delivered to the Agent for the benefit of the Banks.





                                       57
<PAGE>   63
         5.17    Limitation on Dividends and Other Payment Restrictions
Affecting Subsidiaries.  The Borrower will not, and will not permit any
Subsidiary to, directly or indirectly, create, enter into any agreement with
any Person, or otherwise cause or suffer to exist or become effective any
consensual encumbrance or restriction which by its terms expressly restricts
the ability of any Subsidiary to (i) pay dividends, in cash or otherwise, or
make any other distributions on its capital stock, (ii) pay any Indebtedness
owed to the Borrower or any Subsidiary, (iii) make loans or advances to the
Borrower or any Subsidiary or (iv) transfer any of its Property or any assets
to the Borrower or any Subsidiary, except encumbrances or restrictions
contained in any agreement or instrument (a) existing on the date hereof and
listed on Schedule 5.17; (b) relating to any property acquired by the Borrower
or any of its Subsidiaries after the date hereof, provided that such
encumbrance or restriction relates only to the property which is acquired; (c)
relating to any Funded Debt of any Subsidiary at the date  of  acquisition  of
such  Subsidiary  by  the  Borrower or  any  Subsidiary  of the





                                       58
<PAGE>   64
Borrower; provided that such Funded Debt was not incurred in connection with or
anticipation of such acquisition; (d) arising pursuant to an agreement
effecting a refinancing of Funded Debt issued pursuant to an agreement referred
to in the foregoing clauses (a) through (c), so long as the encumbrances and
restrictions contained in any such refinancing agreement are no more
restrictive than the encumbrances and restrictions contained in such
agreements; (e) which constitute customary provisions restricting subletting or
assignment of any lease of the Borrower or any Subsidiary or provisions in
agreements that restrict the assignment of such agreement or any rights
thereunder; or (f) which constitute restrictions on the sale or other
disposition of any property securing Indebtedness as a result of a Permitted
Lien on such Property.

         5.18    Limitation on Asset Sales.  The Borrower shall not engage in,
and shall not permit any Subsidiary (other than a Non-Recourse Subsidiary) to
engage in, any Asset Sale unless:

                 (i)      except in the case of an Asset Sale resulting from
         the requisition of title to, seizure or forfeiture of any Property or
         assets or any actual or constructive total loss or an agreed or
         compromised total loss, the consideration received by the Borrower or
         such Subsidiary for such Asset Sale at the time thereof is at least
         equal to the Fair Market Value of the property; and

                 (ii)     the Net Available Proceeds of an Asset Sale engaged
         in by such Person are applied to the acquisition of one or more
         Replacement Assets within 270 days after the related Asset Sale,
         provided that no Asset Sale or Asset Sales shall be permitted, and the
         occurrence of any such Asset Sale or Asset Sales shall constitute a
         breach of this Section 5.18, if the Excess Proceeds from all Asset
         Sales exceeds $15,000,000 on the 271st day after the related Asset
         Sale.

         5.19    Limitation on Sale and Lease-Back Transactions.  The Borrower
will not, and will not permit any Subsidiary (other than a Non-Recourse
Subsidiary) to, directly or indirectly, enter into, assume, guarantee or
otherwise become liable with respect to any Sale and Lease-Back Transaction if
the lease obligations of the Borrower or any such Subsidiary created or
incurred in connection with such Sale and Lease-Back Transaction constitute
Capital Lease Obligations, unless such Sale and Lease-Back Transaction would
not result in an Event of Default arising hereunder, including without limiting
the generality of the foregoing, under Sections 5.05 or 5.07 hereof.  Any Sale
and Lease-Back Transaction that the Borrower or any Subsidiary enters into that
does not result in the creation or incurrence of any Capital Lease Obligation
of the Borrower or any Subsidiary, shall be deemed to constitute an Asset Sale.


                      ARTICLE VI -- DEFAULTS AND REMEDIES

         6.01    Events of Default.  If any of the following events shall occur
and be continuing (each an "Event of Default"):

         (a)     The Borrower shall fail to pay or prepay any principal of or
interest on any of the Notes as and when due, or the Borrower or any of the
Significant Subsidiaries shall fail to pay





                                       59
<PAGE>   65
any other Obligation hereunder or under any other Loan Document within three
days of the date when due; or

         (b)(i)  Any representation or warranty made by the Borrower herein or
by any of the Significant Subsidiaries in any other Loan Document to which the
Borrower or any of the Significant Subsidiaries, is a party, shall prove to
have been incorrect or untrue in any material respect as of the date hereof or
thereof; or (ii) any representation, financial statement, report, certificate
or written or electronic data furnished or made by or at the request of the
Borrower or any of the Significant Subsidiaries (or any officer, accountant or
attorney of the Borrower or any of the Significant Subsidiaries) hereunder or
thereunder proves to have been incorrect, misleading or untrue in any material
respect as of the date as of which the facts therein set forth were stated or
certified, and 10 days shall have elapsed since the day that the Agent sent
notice of such matter to the Borrower; or

         (c)     Default shall be made in the due observance or performance of,
or compliance with, (i) any of the covenants or agreements contained in Article
V hereof, (ii) the covenants in Section 4.01 hereof, and such default shall
continue unremedied for a period of five days after such default becomes known
to Borrower, (iii) any other covenants or agreements contained in this
Agreement or in any of the other Loan Documents, and such default shall
continue unremedied for a period of 30 days after such default becomes known to
Borrower or (iv) the occurrence of any event or circumstance which constitutes
an "event of default" under any of the other Loan Documents; or

         (d)     a Change of Control shall have occurred; or

         (e)     The Borrower or any of the Significant Subsidiaries shall (i)
dissolve or terminate its existence (except for mergers of Significant
Subsidiaries expressly permitted hereunder), or (ii) discontinue its usual
business, or (iii) apply for or consent to the appointment of a receiver,
trustee, custodian or liquidator of it or of all or a substantial part of its
property, or (iv) generally fail to pay its debts as they come due in the
ordinary course of business, or (v) commence, or file an answer admitting the
material allegations of or consenting to, or default in a petition filed
against it in, any case, proceeding or other action under any existing or
future law of any jurisdiction, domestic or foreign, relating to bankruptcy,
insolvency, reorganization or relief of debtors, or seeking to have an order
for relief entered with respect to it under the Federal Bankruptcy Code, or
seeking reorganization, arrangement, adjustment, winding-up, liquidation,
dissolution, composition or other similar relief with respect to it or its
debt; or

         (f)     A receiver, conservator, liquidator, custodian or trustee of
the Borrower or any of its Subsidiaries or any of their respective properties
is appointed by the order or decree of any court or agency or supervisory
authority having jurisdiction, and such decree or order remains in effect for
more than 60 days; or the Borrower or any of its Subsidiaries obtains an order
for relief under the Federal Bankruptcy Code; or any of the property of the
Borrower or any of its Subsidiaries is sequestered by court order and such
order remains in effect for more than 60 days; or a petition is filed or a
proceeding is commenced against the Borrower or any of its Subsidiaries under
any bankruptcy, reorganization, arrangement, insolvency, readjustment of





                                       60
<PAGE>   66
debt, dissolution or liquidation law of any jurisdiction, whether now or
hereafter in effect, and is not dismissed within 60 days after such filing; or

         (g)     The occurrence of any event, circumstance or condition which
would constitute a default for Borrower or any of its Subsidiaries of any
agreement, contract, promissory note, bond, debenture, promissory note, loan
agreement, indenture, other evidence of Indebtedness, lien instrument or the
like to which the Borrower or any of its Subsidiaries is a party or by which
any of its properties are subject and which evidences or relates to a Funded
Debt or Funded Debts of the Borrower which Funded Debt, exceeds $5,000,000 for
any single Indebtedness or in an aggregate amount in excess of $10,000,000 for
all Indebtedness, whether or not a party thereto exercises any of its rights
and remedies with respect to any such default; provided however, that an event
of default under the NN-1 Rig Facility shall not constitute an Event of Default
under this Subsection (g); or

         (h)     The levy or execution of any attachment, execution or other
process against any material part of the properties or interests in property of
the Borrower or any of the Significant Subsidiaries, which is not timely and
completely stayed by appropriate proceedings and/or bonding requirements; or

         (i)     Any court shall find or rule, or the Borrower or any of the
Significant Subsidiaries shall assert or claim, that this Agreement or any of
the Loan Documents executed in connection herewith does not or will not
constitute the legal, valid, binding and enforceable obligations of the party
or parties (as applicable) thereto; or

         (j)     The entry by a court of competent jurisdiction of one or more
judgments or orders against the Borrower or any Subsidiary in an uninsured or
unindemnified aggregate amount in excess of $5,000,000 which remains
undischarged or unsatisfied for a period of 30 consecutive days after the
principal right to appeal therefrom has expired; or

         (k)     The Borrower or any of the Significant Subsidiaries shall have
concealed, removed, or permitted to be concealed or removed, any part of its
property, with intent to hinder, delay or defraud its creditors or any of them,
or made or suffered a transfer of any of its property which may be fraudulent
under any bankruptcy, fraudulent conveyance or similar law; or shall have made
any transfer of its property to or for the benefit of a creditor at a time when
other creditors similarly situated have not been paid, or shall have suffered
or permitted, while Insolvent, any creditor to obtain a Lien upon any of its
property through legal proceedings or distraint or other process which is not
vacated within sixty days from the date thereof; or

         (l)     The destruction or occurrence of substantial damage to a
material part of the properties or assets of the Borrower and the Significant
Subsidiaries, taken as a whole, for which there is no or substantially no
insurance coverage in respect of and/or for which no or substantially no
insurance coverage will be paid in respect thereto; or

         (m)     With respect to any Plan as to which any of the Borrower or
any other member of the Controlled Group may have a liability, (i) there shall
exist a deficiency in excess of $1,000,000 in the Plan's assets available to
satisfy the benefits guaranteeable under ERISA with





                                       61
<PAGE>   67
respect to such Plan, (a) steps are undertaken to terminate such Plan, (b) such
Plan is terminated, or (c) any Reportable Event which presents a material risk
of termination with respect to such Plan shall occur, or (ii) a failure to
contribute funds occurs with respect to any Plan sufficient to give rise to a
Lien under Section 302(f) of ERISA; or

         (n)     The Borrower or any of its Subsidiaries shall be required
under any Environmental Law (i) to implement any remedial, neutralization, or
stabilization process or program, the cost of which could reasonably be
expected to result in or constitute a Material Adverse Effect on the Borrower
and its Consolidated Subsidiaries taken as a whole, or (ii) to pay any penalty,
fine or damages in an aggregate amount of $10,000,000 or more, for which there
is no insurance coverage;

then the Agent, may, with the consent of the Determining Lenders, or shall,
upon the direction of the Determining Lenders, declare the unpaid principal
portion of the Obligations to be forthwith due and payable, whereupon the said
portion of the Obligations and all other portions of the Obligations then
accrued, earned and unpaid shall become immediately due and payable by the
Borrower without demand, presentment for payment, notice of non-payment,
protest, notice of protest, notice of intent to accelerate maturity, notice of
acceleration of maturity or any other notice of any kind to the Borrower or any
of the Significant Subsidiaries, or any other Person liable thereon or with
respect thereto, all of which are hereby expressly waived by the Borrower and
each of the Significant Subsidiaries and each other Person liable thereon or
with respect thereto, anything contained herein or in any of the other
documents or instruments to the contrary notwithstanding; and upon the
happening of any Event of Default referred to in Section 6.1(e) or Section
6.1(f), the unpaid principal portion of the Obligations and all other portions
of the Obligations then accrued, earned and unpaid shall become automatically
due and payable by the Borrower without demand, presentment for payment, notice
of nonpayment, protest, notice of protest, notice of intent to accelerate
maturity, notice of acceleration of maturity or any other notice of any kind to
the Borrower or any of the Significant Subsidiaries or any other Person liable
thereon or with respect thereto, all of which are expressly waived by the
Borrower and each of the Significant Subsidiaries and each other Person liable
thereon or with respect thereto, anything contained herein or in any document
or instrument to the contrary notwithstanding.  Further, upon any Default or
Event of Default, each of the Banks shall have all other rights and remedies as
set forth herein and in the other Loan Documents and as otherwise provided at
law or in equity, all such rights and remedies being cumulative, including, but
without limitation, the right, without prior notice to the Borrower or any of
the Significant Subsidiaries or any other Person liable with respect to the
Obligations, to set-off and apply any and all deposits (general or special,
time or demand, provisional or final) at any time held or any other
indebtedness at any time owing by any of the Banks to, or for the credit or
account of, the Borrower or any of the Significant Subsidiaries against any
indebtedness owed to the Banks by the Borrower or any Significant Subsidiary
party to the Guaranty, irrespective of whether or not the Agent or such Banks
shall have made demand under this Agreement or any other Loan Document;
provided, that any exercise of said set-off by any Bank shall be subsequently
followed by notice from such Bank to the Borrower of such right exercised, but
the failure to give such notice shall in no manner affect the right of the
Banks in respect to set-offs and corresponding applications of funds.





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         6.02    Cash Collateral Account.  Without limiting its obligations
under, or the terms and provisions of, Section 6.01 hereof, the Borrower hereby
agrees that upon the occurrence and during the continuance of any Event of
Default, the Borrower shall, upon demand by the Agent pay (in the case of any
Event of Default specified in paragraph 6.01(e) or 6.01(f) hereof, forthwith,
without any demand or the taking of any other action by the Banks) to the Agent
for the benefit of the Banks an amount in immediately available funds equal to
the then aggregate undrawn face amount of all Letters of Credit.  All amounts
received by the Agent pursuant to this Section 6.02 or pursuant to any required
prepayment under Section 2.03 (and all investments of such amounts and earnings
therein and proceeds thereof) shall be held by the Agent in a cash collateral
account with the Agent entitled "the Noble Drilling Corporation Letter of
Credit Cash Collateral Account" (the "Collateral Account") as collateral for
the prompt payment and performance when due of all Letter of Credit
Liabilities, and following the satisfaction of all Letter of Credit
Liabilities, as additional collateral for all other Obligations.  The balance
in the Collateral Account from time to time (including all earnings thereon and
proceeds thereof) shall be invested and reinvested by the Agent in the name of
the Agent in interest bearing obligations (but maturing not later than 15 days
after the date acquired) as the Borrower shall from time to time specify to the
Agent, and the Borrower hereby authorizes and directs the Agent to collect and
receive any earnings and proceeds of any such obligations and to credit the net
amount of all such receipts to the Collateral Account.  If and to the extent so
requested by the Borrower from time to time, Agent will reduce the Collateral
Account (and liquidate any investments therein to the extent necessary) in an
amount equal to the lesser of (a) the excess, if any, of the then outstanding
balance in the Collateral Account over the Total Letter of Credit Liabilities
and (b) the minimum amount necessary to be held in the Collateral Account so
that the Borrower will not be obligated because of Section 2.03 to make a
Required Payment, and pay such amount to the Borrower, provided that no such
reduction or payment shall be made if a Default has occurred and is continuing
or would result therefrom.  The proceeds of all dispositions or collections of
collateral, in connection with the Agent's exercise on behalf of the Banks of
their rights as a secured party or pursuant to the foregoing, will be applied
to such of the Obligations, in such order and in such manner, and in all
respects to such of the promissory notes and other Indebtedness constituting a
part of the Obligations, as the Agent shall see fit and determine (with respect
to the Borrower) in its sole and absolute discretion.  At such time as no
Default or Event of Default is continuing hereunder, the Agent shall, upon
demand of the Borrower, return to the Borrower the proceeds of the Collateral
Account not previously applied to the Obligations.

         6.03    Additional Cross Default Provisions.  The occurrence of a
Default or an Event of Default under this Agreement, the Loan Documents, or any
default under the terms of any security agreement, guaranty, agreement or
instrument securing the Obligations will constitute an Event of Default
hereunder.

                      ARTICLE VII -- TERMINATION OF LOANS

         Upon the occurrence of any Default and so long as such continues to
exist, the Agent may, without prior notice to the Borrower or any of the
Significant Subsidiaries or any other Person, terminate, temporarily or
permanently as chosen by the Agent, (i) the Revolving Loan Commitment, (ii) the
L/C Facility and any obligation of First Interstate (or any other Person
hereunder) or commitment to issue Letters of Credit, and (iii) the obligations
of the Banks to





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advance any Loans or extend any other type of credit or financial
accommodations hereunder, unless and until the Agent shall reinstate same (on
additional conditions, if any, submitted by the Banks or the Determining
Lenders, as may be required under Article IX hereof) in writing; provided,
however, upon the occurrence of any Default referred to in Sections 6.01(e) or
6.01(f), or upon acceleration of the maturity of the Notes, (a) the Revolving
Loan Commitment, (b) the L/C Facility and any obligation or commitment to issue
Letters of Credit, and (c) any and all obligations of the Banks hereunder to
make any Loans or extend any other type of credit or financial accommodations
hereunder shall automatically be permanently terminated; provided further,
however, notwithstanding any such termination of such obligation of the Banks,
all covenants, agreements, obligations, liens and undertakings of each of the
Borrower and the Significant Subsidiaries shall remain in full force and
effect, except that, the Commitment Fee payable pursuant hereto shall not
accrue during any period while the Revolving Loan Commitment has been
terminated.

                      ARTICLE VIII -- CONDITIONS PRECEDENT

         8.01    Conditions Precedent to Initial Loan.  The obligation of First
Interstate to issue the initial Letters of Credit and the obligation of the
Banks to make the initial Loan hereunder, in addition to the matters set forth
in Section 2.03 hereof, shall be subject to the completion of the following
conditions precedent, which shall be completed to the reasonable satisfaction
of the Agent:

         (a)     The Agent shall have received the Notes, and prior to the
issuance of each Letter of Credit, an Application all duly executed and
delivered by the Borrower.

         (b)     The Guaranty shall have been duly and validly executed and
delivered to the Agent in form and substance reasonably satisfactory to the
Agent.

         (c)     The Agent shall have received, certified by the Secretary of
each of the Borrower, the Significant Subsidiaries signing the Guaranty and the
Foreign Subsidiaries that are Significant Subsidiaries, with respect to each
such Person, (i) copies of resolutions of its Board of Directors authorizing
the creation, issuance, execution, delivery and performance of each of this
Agreement, the Notes, the Applications and all other Loan Documents to which
each is a party which resolutions shall recite, in part, that its Board of
Directors found, in its judgment, that (A) adequate value and fair
consideration was received by each such Person for entry into and performance
of such agreements and (B) the incurrence of obligations evidenced by such
agreements are in the best interest of each such Person and may be expected to
benefit each such Person, directly or indirectly, (ii) certificate of
incumbency of authorized representatives of each such Person, signed by the
Secretary of each such Person, which certificate shall recite the names of the
Persons authorized to execute and deliver each of this Agreement, the Notes and
all other Loan Documents to which the Borrower and each of the Significant
Subsidiaries is a party and to perform the obligations hereunder and
thereunder, display specimen signatures of such Persons, and state that the
Agent and the Banks may conclusively rely on such certificate until it shall
receive and has had reasonable time to act upon subsequent certificates of the
Secretary of each such Person, as applicable, amending the prior certificate
and submitting the names and signatures of the Persons specified in such
further certificate, and (iii) a copy of the





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certificate of incorporation or articles of incorporation as may be appropriate
and bylaws of each such Person, with all amendments as in force as of the date
hereof.

         (d)     The Agent shall have received from Thompson & Knight, a
Professional Corporation, legal counsel for the Borrower and each of the
Significant Subsidiaries, a favorable written opinion, dated as of the date
hereof and addressed to the Agent and to the Banks, in form, substance and
scope satisfactory and acceptable to the Agent.

         (e)     The Agent shall have received from each of (i) the Borrower
and the Significant Subsidiaries, certificates of existence and certificates of
good standing issued from the respective jurisdictions of their incorporation,
and (ii) with respect to the Borrower and each of the Significant Subsidiaries
party to the Guaranty, certificates of good standing and authority to transact
business as a foreign corporation from all jurisdictions wherever the ownership
of their assets or the conduct of their business requires such qualification,
in each case, issued as of the most recent date practicable except where the
failure so to qualify would not have a Material Adverse Effect on such Person
failing so to qualify.

         (f)     The Agent shall have received (i) a Loan Formula Certificate
appropriately completed and duly executed by the Borrower as well as a summary
aging report with respect to accounts receivable of the Borrower and the
Significant Subsidiaries, both completed as of April 30, 1994, and (ii) those
items of information listed in Section 4.01(d) hereof, containing information
as of April 30, 1994.

         (g)     The Agent shall have received evidence satisfactory to it that
all of the insurance requirements applicable to the Borrower, the Significant
Subsidiaries and their businesses and properties as set forth in Section 4.08
hereof have been met.

         (h)     The Agent (i) shall have received for the Banks the Facility
Fee provided for in Section 2.06(c), in immediately available funds and (ii)
the Agent Fee.

         (i)     The Borrower shall have presented proof to the Agent that all
revolving credit facilities for Funded Debt of the Borrower or its Subsidiaries
except for Non-Recourse Subsidiaries have been terminated and repaid in full,
except for Noble Drilling (Canada) Ltd.'s Canadian dollar credit facility
providing for up to C$1,000,000 in revolving credit.

         (j)     The Agent shall have received all exhibits, annexes and
schedules herein referenced and such additional reports, certificates,
documents, statements, agreements and instruments, including without limitation
the Security Agreement, in form and substance reasonably satisfactory to the
Agent, as the Agent shall have reasonably requested from any of the Borrower,
the Significant Subsidiaries and their counsel.

         (k)     The Borrower shall have executed and delivered to the Agent
for the benefit of the Banks, such security agreements, financing statements
and other lien instruments, as the Agent may require to obtain perfected first
priority liens on Intercompany Revolving Credit Notes.





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         8.02    Conditions Precedent to Each Loan. At the time of the making
by the Banks of each Loan or issuance by First Interstate of a Letter of
Credit, including the initial Loan or Letter of Credit but not including
continuations or conversions pursuant to Section 2.04 (before as well as after
giving effect to such Loan and to the proposed use of proceeds thereof):

         (a)  Borrower shall have duly executed and delivered the Notes.

         (b)  There shall exist no Default or Event of Default.

         (c)  Except for facts timely disclosed to the Agent from time to time
in writing, not materially more adverse to the Borrower and its Subsidiaries
than those existing on the date of the initial Loan hereunder, all
representations and warranties contained herein and in the other Loan Documents
executed and delivered on or after the date hereof shall be true and correct in
all material respects with the same effect as though such representations and
warranties had been made on and as of the date of such Loan.

         (d)  The Agent shall have received such other documents, including
such other guaranties and Intercompany Revolving Credit Notes as may be
required under Section 4.11 hereof, as Agent or any of the Banks or counsel to
the Agent may reasonably request, all in form and substance satisfactory to the
Agent.

                            ARTICLE IX -- THE AGENT

         9.01    Authorization and Action.  (a)  Each of the Banks hereby
appoints and irrevocably authorizes Agent to take such action as Agent on its
behalf and to exercise such powers under this Agreement and the other Loan
Documents as are delegated to Agent by the terms of the Loan Documents,
together with such powers as are reasonably incidental thereto.  The Agent, its
Affiliates and their respective officers, shareholders, directors, employees
and agents shall not (i) have any duties or responsibilities except those
expressly set forth in this Agreement and in the Loan Documents, and shall not
by reason of this Agreement or any of the Loan Documents be a trustee for any
of the Banks; (ii) be responsible to any of the Banks for any recitals,
statements, representations or warranties contained in this Agreement, any of
the Loan Documents or any certificate or other document referred to or provided
for in, or received by any of them under, this Agreement or any of the other
Loan Documents or for any failure by any Person to perform any of its
obligations hereunder or thereunder; and shall have no duty to inquire or pass
upon any of the foregoing matters; (iii) be required to initiate or conduct any
litigation or collection proceedings hereunder or under any of the Loan
Documents except to the extent requested by the Determining Lenders; (iv) be
responsible for any mistake of law or fact or any action taken or permitted to
be taken by it hereunder or under any of the Loan Documents or any other
document or instrument referred to or provided for herein or therein or in
connection herewith or therewith, including pursuant to its own negligence,
except for its own gross negligence or willful misconduct; (v) be bound by or
obliged to recognize any agreement among or between the Borrower and any one or
more of the Banks (other than this Agreement and the Loan Documents) regardless
of whether the Agent has knowledge of the existence of any such Agreement or
the terms and provisions thereof; (vi) be charged with notice or knowledge of
any fact or information not herein set out or provided to the Agent in





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accordance with the terms of this Agreement or any of the Loan Documents; (vii)
be responsible for any delay, error, omission or default of any third party
mail, telegraph, telecopy or operator; or (viii) be responsible for the edicts
or acts of any Governmental Authority.  The Agent may employ agents and
attorneys in fact and shall not be responsible for the negligence or misconduct
of any such agents or attorneys in fact selected by it with reasonable care.
As to any matters not expressly provided for by this Agreement and the other
Loan Documents (including without limitation enforcement or collection of the
Notes), Agent shall not be required to exercise any discretion or take any
action, but shall be required to act or to refrain from acting (and shall be
fully protected in so acting or refraining from acting) upon the instructions
of Determining Lenders (or all of the Banks, if required under Section 9.01(b)
hereof) and such instructions shall be binding upon all of the Banks; provided,
however, that Agent shall not be required to take any action which may subject
Agent to personal liability or which is contrary to any Loan Document or
applicable law.  Agent agrees to give to each of the Banks notice of each
notice given to it by the Borrower pursuant to the terms of this Agreement, and
to distribute to each of the Banks in like funds all amounts delivered to Agent
by the Borrower for the ratable benefit of each in accordance with the
Specified Percentage of each such Bank, except that funds provided by the
Borrower pursuant to Section 6.02 hereof to collateralize the Letter of Credit
Liabilities shall be held by Agent in accordance with Section 6.02 hereof.

         (b)  Upon any occasion requiring or permitting an approval, consent,
waiver, election or other action on the part the Determining Lenders, action
shall be taken by the Agent for and on behalf of, or for the benefit of all
Banks, upon the direction of the Determining Lenders, and any such action shall
be binding on all Banks.  Unless all Banks agree in writing, no amendment,
modification, consent or waiver shall be effective which

                 (i)      increases the amount of the Loans or the availability
         of Letters of Credit, or increases the Commitment or Specified
         Percentage of any Bank;

                 (ii)     reduces the interest, principal or commitment fees
         owing hereunder or under the Notes;

                 (iii)    extends the fixed date on which any sum is due
         hereunder or under the Notes;

                 (iv)     waives an Event of Default arising from a failure to
         pay principal or interest on a Loan within the applicable grace
         period, if any;

                 (v)      changes the provisions of this Section 9.01; or

                 (vi)     releases in whole or in part any Guaranty or any
         collateral, if any, securing the obligations arising hereunder.

         9.02    Agent's Reliance, Etc.  Neither Agent, nor any of its
directors, officers, agents, employees, or representatives shall be liable for
any action taken or omitted to be taken by it or them under or in connection
with this Agreement or any other Loan Documents, except for its or their own
gross negligence or willful misconduct.  Without limiting the generality of the





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foregoing, Agent (a) may treat the payee of any Note as the holder thereof
until Agent receives written notice of the assignment or transfer thereof
signed by such payee and in form satisfactory to Agent; (b) may consult with
legal counsel (including counsel for Borrower or any of its Subsidiaries),
independent public accountants, and other experts selected by it, and shall not
be liable for any action taken or omitted to be taken in good faith by it in
accordance with the advice of such counsel, accountants, or experts; (c) makes
no warranty or representation to any of the Banks and shall not be responsible
to any of the Banks for any statements, warranties, or representations made in
or in connection with this Agreement or any other Loan Documents; (d) shall not
have any duty to ascertain or to inquire as to the performance or observance of
any of the terms, covenants or conditions of this Agreement or any other Loan
Documents on the part of Borrower or its Subsidiaries or to inspect the
Properties (including the books and records) of Borrower or its Subsidiaries;
(e) shall not be responsible to any of the Banks for the due execution,
legality, validity, enforceability, genuineness, sufficiency, or value of this
Agreement, any other Loan Documents, or any other instrument or document
furnished pursuant hereto or thereto; and (f) shall incur no liability under or
in respect of this Agreement or any other Loan Documents by acting upon any
notice, consent, certificate, or other instrument or writing (which may be by
telegram, cable, telex, or telecopy) believed by it to be genuine and signed or
sent by the proper party or parties.

         9.03    First Interstate Bank and Affiliates.  With respect to its
Commitment, its Advances, and any Loan Documents, First Interstate shall have
the same rights under this Agreement and the other Loan Documents as any other
of the Banks and may exercise the same as though it were not Agent.  First
Interstate and its Affiliates may accept deposits from, lend money to, act as
trustee under indentures of, and generally engage in any kind of business with,
any of the Borrower or its Affiliates, any Affiliate thereof, and any Person
who may do business therewith, all as if First Interstate were not Agent and
without any duty to account therefor to any of the Banks.

         9.04    Lender Credit Decision.  Each Bank acknowledges that it has,
independently and without reliance upon Agent or any other of the Banks, and
based on the financial statements referred to in Section 3.09 hereof or
financial statements (in the case of assignees after the date hereof) delivered
subsequent to the date hereof, and such other documents and information as it
has deemed appropriate, made its own credit analysis and decision to enter into
this Agreement and the other Loan Documents.  Each Bank also acknowledges that
it will, independently and without reliance upon Agent or any other of the
Banks and based on such documents and information as it shall deem appropriate
at the time, continue to make its own credit decisions in taking or not taking
action under this Agreement and the other Loan Documents.

         9.05    Indemnification by Lenders.  Each of the Banks severally, and
not jointly, agrees to indemnify and hold harmless Agent, in accordance with
the Specified Percentage of each and to the extent not reimbursed by the
Borrower, from and against any and all liabilities, obligations, losses,
damages, penalties, actions, judgments, suits, costs, expenses, or
disbursements of any kind or nature whatsoever which may be imposed on,
incurred by, or asserted against Agent in any way relating to or arising out of
any Loan Documents or any action taken or omitted by Agent thereunder,
including any negligence of Agent; provided, however, that none of the Banks
shall be liable for any portion of such liabilities, obligations,





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losses, damages, penalties, actions, judgments, suits, costs, expenses, or
disbursements resulting from Agent's gross negligence or willful misconduct.
Without limitation of the foregoing, each of the Banks agrees, severally and
not jointly, to reimburse Agent, based on its Specified Percentage of the total
obligation, promptly upon demand for any out-of-pocket expenses (including
attorneys' fees) incurred or accrued by Agent in connection with the
preparation, execution, delivery, administration, modification, amendment, or
enforcement (whether through negotiation, legal proceedings or otherwise) of,
or legal advice in respect of rights or responsibilities under, the Loan
Documents.  The indemnity provided in this Section 9.05 shall survive the
termination of this Agreement.

         9.06    Successor Agent.  Agent may resign at any time by giving
written notice thereof to each of the Banks and to the Borrower, and may be
removed at any time with or without cause by the action of the Determining
Lenders.  Upon any such resignation or removal, Determining Lenders shall have
the right to appoint a successor Agent.  If no successor Agent shall have been
so appointed and shall have accepted such appointment within 30 days after a
retiring Agent's giving of notice of resignation or within 30 days after notice
to a removed Agent of such removal, then the retiring or removed Agent may, on
behalf of the Banks, appoint a successor Agent, which shall be a commercial
bank organized under the laws of the United States of America or of any State
of the United States of America and having a combined capital and surplus of at
least $50,000,000 and not in receivership or conservatorship.  Upon the
acceptance of any appointment as Agent hereunder by a successor Agent, such
successor Agent shall thereupon succeed to and become vested with all the
rights and duties of the retiring or removed Agent, and the retiring or removed
Agent shall be discharged from its duties and obligations under the Loan
Documents, provided that if the retiring or removed Agent is unable to appoint
a successor Agent, Agent shall, after the expiration of a 60 day period from
the date of notice, be relieved of all obligations as Agent hereunder.
Notwithstanding any Agent's resignation or removal hereunder, the provisions of
this Article shall continue to inure to its benefit as to any actions taken or
omitted to be taken by it while it was Agent under this Agreement.

         9.07    Sharing of Payments.  If any of the Banks shall obtain any
payment (whether voluntary, involuntary, through the exercise of any right of
set-off, or otherwise) on account of its Advances in excess of its Pro Rata
Share of payments made by Borrower, such Bank shall forthwith purchase
participations in Advances made by the other Lenders as shall be necessary to
share the excess payment pro rata with each of them; provided, however, that if
any of such excess payment is thereafter recovered from the purchasing Bank,
its purchase from each Bank shall be rescinded and each Bank shall repay the
purchase price to the extent of such recovery together with a Pro Rata Share of
any interest or other amount paid or payable by the purchasing Bank in respect
of the total amount so recovered.  Borrower agrees that any Bank so purchasing
a participation from another Bank pursuant to this Section 9.07 may, to the
fullest extent permitted by law, exercise all its rights of payment (including
the right of set-off) with respect to such participation as fully as if such
Bank were the direct creditor of Borrower in the amount of such participation.

         9.08    Right of Set-off.  Upon the occurrence and during the
continuance of any Event of Default, each of the Banks is hereby authorized at
any time and from time to time, to the





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fullest extent permitted by law, to set-off and apply any and all deposits
(general or special, time or demand, provisional or final) at any time held and
other indebtedness at any time owing by such Bank to or for the credit or the
account of Borrower against any and all of the obligations of Borrower now or
hereafter existing under this Agreement and the other Loan Documents, whether
or not the Agent or any of the Banks shall have made any demand under this
Agreement or the other Loan Documents.  Each of the Banks shall promptly notify
Borrower after any such set-off and application, provided that the failure to
give such notice shall not affect the validity of such set-off and application.
The rights of each Lender under this Section 9.08 are in addition to other
rights (including, without limitation, other rights of set-off) which each of
the Banks may have.

                           ARTICLE X -- MISCELLANEOUS

         10.01   No Waivers Except by Writing; Governing Law.  No failure or
delay on the part of the Agent in exercising any power or right hereunder or
under any other Loan Document shall operate as a waiver thereof, nor shall any
single or partial exercise of any such right or power, or any abandonment or
discontinuance of steps to enforce such a right or powers preclude any other or
further exercise thereof or the exercise of any other right or power.  No
modification or waiver of any provision of this Agreement or any other Loan
Document nor consent to any departure by the Borrower, the Significant
Subsidiaries or any other Person thereof shall in any event be effective unless
the same shall be in writing, and then such waiver or consent shall be
effective only in the specific instance and for the purpose of which given.
Notwithstanding the foregoing, Article IX may be amended at any time, in whole
or in part, by written agreement of the Determining Lenders alone (except that
Section 9.01(b) may be amended only by unanimous written consent of all of the
Banks), and no consent of the Borrower shall be required to effectuate any such
amendment of Article IX.  No notice to or demand on the Borrower, the
Significant Subsidiaries or any other Person in any case shall entitle the
Borrower, the Significant Subsidiaries or such other Person to any other or
further notice or demand in similar or other circumstances.  This Agreement and
the other Loan Documents shall be deemed to be contracts under the internal
laws of the State of Texas and for all purposes shall be construed and enforced
in accordance with the laws of the State of Texas, and, to the extent
applicable, the laws of the United States of America.

         10.02   Usury Laws.  It is the intent of the Banks, the Borrower and
each of the Significant Subsidiaries in the execution and performance of this
Agreement, the Notes and the other Loan Documents to which each is a party to
remain in strict compliance with all Applicable Law, from time to time in
effect, including, without limitation, usury laws.  In furtherance thereof, the
Banks, the Borrower and each of the Significant Subsidiaries party hereto
stipulate and agree that none of the terms and provisions contained in this
Agreement, the Notes, the Applications or any of the other Loan Documents shall
ever be construed to create a contract to pay, for the use, forbearance or
detention of money, interest at a rate in excess of the Maximum Rate.

         Neither the Borrower, the Significant Subsidiaries nor any other
Person obligated hereon or in respect hereto shall ever be required to pay
unearned interest on any Loan or on any other extension of credit or on any
other indebtedness owed to the Banks, or to pay interest on any





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such amounts at a rate in excess of the Maximum Rate, or in an amount in excess
of the maximum amount of interest permitted to be charged under Applicable Law,
and the provisions of this Section 10.02 shall control over all other
provisions of this Agreement, the Applications, the Notes and the other Loan
Documents which may be in apparent conflict herewith.  For purposes of this
Agreement "interest" shall include the aggregate of all charges which
constitute interest under Applicable Law that are contracted for, charged,
reserved, received or paid under the Notes, this Agreement or any of the Loan
Documents.  If the maturity of any Loan or any other extension of credit or
other indebtedness owed by the Borrower hereunder or under any of the other
Loan Documents is prepaid or accelerated for any reason, or if under any other
contingency, the effective rate or amount of interest which would otherwise be
payable under this Agreement, the Notes or any of the other Loan Documents,
would exceed the Maximum Rate or maximum amount of interest that the Banks or
any of their respective successors or assigns is allowed by Applicable Law to
charge, contract for, take or receive, or in the event the Bank or any of its
successors or assigns shall charge, contract for, take, reserve or receive
monies that are deemed to constitute interest which would, in the absence of
this provision, increase the effective rate or amount of interest payable under
this Agreement, the Notes or any of the other Loan Documents to a rate or
amount in excess of that permitted to be charged, contracted for, taken,
reserved or received under the Applicable Law then in effect, then the
principal amount of the Notes or other extension of credit or other
indebtedness, or the amount of interest which would otherwise be payable
thereunder, shall be reduced to the amount allowed under said laws as now or
hereafter construed by the courts having jurisdiction, and all such monies so
charged, contracted for, taken, reserved or received that are deemed to
constitute interest in excess of the Maximum Rate or maximum amount of interest
permitted by Applicable Law shall be immediately returned to or credited to the
account of the Borrower or other paying Person upon such determination.
Borrower and the Banks further stipulate and agree that, without limitation of
the foregoing, all calculations of the rate or amount of interest contracted
for, charged, taken, reserved or received under this Agreement, the Notes or
any of the other Loan Documents which are made for the purpose of determining
whether such rate or amount exceeds the Maximum Rate or the maximum amount of
interest under Applicable Law, shall be made, to the extent permitted by
Applicable Law, by amortizing, prorating, allocating and spreading during the
period of the full stated term of the Notes or other extension of credit, all
interest at any time contracted for, charged, taken, reserved or received from
the Borrower or otherwise by the Banks.

         10.03   Notice.  All notices required or made hereunder shall be
deemed to have been given (i) five Business Days after being deposited in the
United States mail (certified, return receipt requested) or (ii) one Business
Day after being sent by telecopy to any party hereto at its address and
telecopy number given below, or at any other address of which it shall have
notified the other party hereto in writing.  All notices, requests and demands
shall be given to or made upon the respective parties hereto as follows:





                                       71
<PAGE>   77
 If to Borrower or to any of    Noble Drilling Corporation
 its Subsidiaries:              10370 Richmond Avenue, Suite 400
                                Houston, TX  77042
                                Telecopy No. (713) 974-3181
                                Attention:  Byron L. Welliver
                                            Sr. Vice President -- Finance 
                                            and Treasurer

 With a copy to:                Thompson & Knight, a Professional Corporation
                                1700 Pacific Avenue, Suite 3300
                                Dallas, TX 75201
                                Telecopy No. (214) 969-1751
                                Attention:  Robert D. Campbell, Esq.

If to Agent                     First Interstate Bank of Texas, National
or First Interstate:            Association
                                1000 Louisiana, 3rd Floor
                                Houston, TX  77002
                                Telecopy No. (713) 250-7029
                                Attention:  Carol Birkofer
                                            Assistant Vice President

 With a copy to:                Fulbright & Jaworski L.L.P.
                                1301 McKinney, Suite 5100
                                Houston, TX 77010-3095
                                Telecopy No. (713) 651-5246
                                Attention:  Joshua P. Agrons, Esq.

But actual notice to any party hereto, however given or received, shall always
be effective.  So long as no Event of Default is continuing, copies of
information required under Section 4.01 hereof, Loan Request Forms and
documents related to routine borrowing activities need not be provided to the
legal counsels listed above.

         10.04   Waivers of Certain Rights.  (a) Each of the Borrower, the
Significant Subsidiaries and all sureties, endorsers and guarantors of any of
the Obligations specifically waives any notice of the creation, advancement,
increase, existence, extension or renewal of, or indulgence with respect to,
the Obligations or any part thereof, and of non-payment thereof, or default
thereon, and waives demand, notice of demand, notice of protest, protest,
presentment for payment, presentment, notice of intent to accelerate maturity,
notice of acceleration and any and all other notices with respect to the
Obligations, and waives notice of the amount of the Obligations outstanding at
any time, and agrees that the maturity of the Obligations, and any part
thereof, may be accelerated by the Banks in their sole discretion without
notice to, or consent by, the Borrower, the Significant Subsidiaries or any
other Person, and may be extended or renewed by the Banks as may be agreed by
the Borrower and the Banks without notice to, or consent by, any Persons other
than the Borrower.  The Borrower and each such other Person agree that no
renewal, increase or extension of, or any indulgence with respect to, the
Obligations or





                                       72
<PAGE>   78
any part thereof, no release, substitution or exchange of any security for the
Obligations, or any part hereof, no release of any Person primarily or
secondarily liable on the Obligations or any part thereof, no delay in the
enforcement of payment of the Obligations or any part thereof, and no delay or
omission or lack of diligence or care in exercising any right or power with
respect to the Obligations or any security thereof or guaranty therefor in
connection with the Obligations shall in any manner impair, affect or prejudice
the rights of the Banks hereunder, in connection herewith or in respect to any
Note or Loan Documents executed by the Borrower or any other Person in favor of
the Banks.  The Borrower and each such other Person specifically agree it shall
not be necessary or required, and that neither the Borrower nor any other
Person shall be entitled to require, that the Agent or the Banks file suit or
proceed to obtain or assert a claim for personal judgment against any Person
(including the Borrower) or that the Agent or the Banks proceed against or
foreclose against or seek to realize upon any of the security now or hereafter
existing for the Obligations or file suit or proceed to obtain or assert a
claim for personal judgment against any other party obligated on the
Obligations before, or as a condition of, or any time after enforcing the
liability of the Borrower or any other Person on the Obligations, or
foreclosing upon or otherwise selling or disposing or utilizing any collateral
for the purpose of paying the Obligations or by any part thereof.  The Borrower
and each such other Person expressly waives any right to the benefit of, or to
require or control applications of any security or the proceeds of any security
now existing or hereafter obtained by the Banks as security for the
Obligations, or any part thereof, and agrees that the Banks shall have no duty
or obligation insofar as the Borrower or such other Person is concerned to
apply upon the Obligations, any monies, payments or other property any time
received by or paid to the Agent or the Banks, except as the Banks shall
determine in their sole discretion or as the Banks otherwise may be obligated
pursuant to the terms of this Agreement.

         (b)     To the maximum extent not prohibited by applicable law from
time to time in effect, Borrower hereby knowingly, voluntarily and
intentionally (and after Borrower has consulted with its own attorney)
irrevocably and unconditionally waives the provisions of the Texas Deceptive
Trade Practices-Consumer Protection Act (Texas Business and Commerce Code,
Chapter 17, Subtitle E, Sections 17.41-17.63).

        (c)     THIS AGREEMENT, TOGETHER WITH THE OTHER WRITTEN DOCUMENTS
REQUIRED BY SECTION 8 HEREOF, REPRESENTS AND CONSTITUTES THE FINAL AGREEMENT 
BY AND AMONG THE BORROWER, THE AGENT AND THE BANKS AND MAY NOT BE ALTERED, 
MODIFIED OR CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR 
SUBSEQUENT ORAL AGREEMENTS OF THE BORROWER WITH THE AGENT OR THE BANKS.  
THERE ARE NO WRITTEN OR ORAL AGREEMENTS OR COMMITMENTS AMONG THE BORROWER, 
THE AGENT AND THE BANKS. THIS PROVISION SHALL CONSTITUTE NOTICE TO THE 
BORROWER UNDER SECTION 26.02 OF THE TEXAS BUSINESS & COMMERCE CODE OF THE 
PROVISIONS THEREOF AND HEREOF.

         10.05   Severability of Provisions.  Any provision of this Agreement,
or any other Loan Document, or any portion or portions of such provisions, held
by a court of competent jurisdiction to be invalid, illegal or ineffective
shall not impair, invalidate or nullify the remainder of this Agreement or any
of the other Loan Documents, but the effect thereof shall be confined to such
provision or the portion or portions thereof so held to be invalid, illegal or
ineffective.





                                       73
<PAGE>   79
         10.06   Survival of Representations and Warranties; Unsatisfied
Conditions.  Except as otherwise expressly set forth herein, all
representations and warranties of the Borrower herein shall survive the date of
this Agreement and the making of each Loan hereunder.  Except to the extent, if
at all, expressly waived by the Agent, any condition precedent not timely
performed by or on behalf of the Borrower prior to or at a corresponding
borrowing date shall survive such date, unless otherwise expressly stated in
this Agreement, and shall be deemed to constitute a covenant by the Borrower to
accomplish such condition as promptly as possible.  All payment obligations
hereunder or referenced herein shall survive the termination of this Agreement.

         10.07   Assignments.  (a)  This Agreement shall be binding upon and
inure to the benefit of the parties hereto and their respective successors and
assigns, except that neither the Borrower, any Subsidiary thereof nor any
Person acting on their behalf may assign any of their rights hereunder.

         (b)  Each of the Banks may, transfer and assign to one or more
Eligible Assignees, all or a portion of its rights and obligations under this
Agreement pursuant to an Assignment and Acceptance, provided, however, that (i)
an Eligible Assignee must purchase and acquire in aggregate an interest of at
least $10,000,000, (ii) the assignee shall pay to the Agent a processing
recordation fee of $2,500.00, and (iii) the Borrower shall have consented to
such assignment, such consent not to be unreasonably withheld.  In no event
shall any Bank own a Specified Percentage in excess of that owned by the Bank
which serves as "Agent", without the prior written consent of the Borrower and
all of the other Banks.  Any such assignment shall become effective upon the
recording by the Agent of such assignment in a register kept for such purposes
by the Agent of the resultant effect thereof, and the principal amount
outstanding of the Loans owed to the assignor and assignee, the Agent hereby
agreeing to effect such recordation no later than five (5) Business Days after
its receipt of an Assignment and Acceptance executed by all parties thereto.
Promptly after receipt of an Assignment and Acceptance executed by all parties
thereto, the Agent shall send to the Borrower a copy of such executed
Assignment and Acceptance.  Upon receipt of such executed Assignment and
Acceptance, the Borrower will, at its own expense, execute and deliver new
Notes to the assignor and/or assignee, as appropriate, in accordance with their
respective interests as they appear on such register.  Upon the effectiveness
of any assignment pursuant to this subsection, the assignee shall be deemed
automatically to have become a party hereto, if not already a party hereto, and
shall become one of the "Banks", if not already one of the "Banks", for all
purposes of this Agreement and the other Loan Documents.  The assignor shall be
relieved of its obligations hereunder to the extent of such assignment (and if
the assigning Bank no longer holds any rights or obligations under this
Agreement, such assigning Bank shall cease to be one of the "Banks" hereunder).
The Agent will prepare on the last Business Day of each month during which an
assignment has become effective pursuant to this subsection a new schedule
giving effect to all such assignments effected during such month, and more
promptly provide the same to the Borrower, and the Banks.

         (c)  Each of the Banks may transfer, grant or assign participations in
all or any part of such Bank's interests hereunder pursuant to this subsection
to any Person provided that (i) such Banks shall remain one of the "Banks" for
all purposes of this Agreement and the transferee of such participation shall
not constitute one of the "Banks" hereunder; (ii)  no participant under





                                       74
<PAGE>   80
any such participation shall have rights to approve any amendment to or waiver
this Agreement, the Notes or any of the Loan Documents except to the extent
such amendment or waiver would (A) extend the Credit Maturity Date, (B) reduce
the interest rate (other than as a result of waiving the applicability of any
post fault increases and interest rates) or fees applicable to any of the
Loans, Letters of Credit or commitments hereunder in which such participant is
participating, or postpone the payment of any thereof, or (C) release all or
substantially all of any collateral or guaranties supporting any of the Loans
or Letters of Credit in which such participant is participating.  In the case
of any such participation, the participant shall not have any rights in this
Agreement or any of the Loan Documents (the participant's rights against the
granting Bank in respect of such participation to be those set forth in the
agreement with such Bank creating such participation),  and all amounts payable
by the Borrower hereunder shall be determined as if such Bank had not sold such
participation.  Notwithstanding anything in this Section 10.07(c) to the
contrary, the purchase by each of the Banks of a participation in the Letters
of Credit and any subsequent assignment of all or any part of such Bank's
Specified Percentage in any Letter of Credit and its related Letter of Credit
liabilities pursuant to Section 10.07(b) shall not be considered a
participation pursuant to this Section 10.07(c).

         (d)  Anything contained in this Section 10.07 to the contrary
notwithstanding, no transfer or assignment of the interest or obligations of
any of the Banks hereunder or grant of participations therein shall be
permitted as such transfer, assignment or grant would require the Borrower or
any guarantor party to the Guaranty to file a registration statement with the
Securities and Exchange Commission or to qualify any of the Loans under the
"Blue Sky" laws of any state.

         (e)  Each of the Banks initially part of this Agreement hereby
represents, and each Person becomes one of the Banks pursuant to an assignment
permitted hereunder will, upon its becoming a party to this Agreement represent
that it is a Eligible Assignee, and that it will make or acquire Loans only for
its own account in the ordinary course of its business; provided, however, that
subject to the preceding subsections 10.07(b) through (d), the disposition of
any promissory notes or other evidences of or interests in the Obligations held
by such Banks shall at all times be within its exclusive control.

         (f)  The entries in the register described herein above shall be
conclusive in the absence of manifest error and the Borrower, the Agent and the
Bank issuing Letters of Credit may treat each person whose name is recorded in
such register pursuant to the terms hereof as one of the Banks hereunder for
all purposes of this Agreement and the other Loan Documents.  Such register
shall be available for inspection by the Borrower and any of the Banks at any
reasonable time and from time to time upon reasonable prior notice.

         10.08   Gender and Usage.  As used herein and when required by the
context, each number (singular and plural) shall include all numbers and each
gender shall include all genders.  The words "herein," "hereof," "hereby,"
"hereto," "hereunder" and words of similar import shall mean and refer to this
Agreement rather than to any specified provision of this Agreement.

         10.09   Multiple Counterparts.  This Agreement may be executed in any
number of counterparts, all of which, taken together, shall constitute one and
the same instrument.





                                       75
<PAGE>   81
         10.10   Notices Received by Lender.  Any instrument in writing, telex,
telegram, telecopy or cable received by the Agent in connection with any Loan
hereunder, which purports to be dispatched or signed by or on behalf of the
Borrower shall conclusively be deemed to have been signed by such party, and
Agent and the Banks may rely thereon and shall have no obligation, duty or
responsibility to determine the validity or genuineness thereof or authority of
the Person or Persons executing or dispatching the same.

         10.11   Debtor-Creditor Relationship.  None of the terms of this
Agreement or of any other Loan Document executed in conjunction herewith or
related hereto shall be deemed to give the Agent or the Banks the rights or
powers to exercise control over the business or affairs of the Borrower.  The
relationship between the Borrower and the Banks created by this Agreement is
only that of debtor and creditor.

         10.12   Agreement Controlling.  To the extent that any provision of
the Loan Documents (other than this Agreement) are expressly in direct conflict
with the provisions of this Agreement, the provisions of this    Agreement
shall control and govern.  In all other regards, all provisions of the Loan
Documents are intended to be read and integrated in a harmonious and consistent
manner, including defined terms herein and therein.

         10.13   Integration.  This Agreement, together with all other Loan
Documents, embodies the entire agreement between the parties thereto relating
to the subject matter hereof and thereof, and may be amended or supplemented
only by an instrument in writing executed jointly by an authorized officer of
each of the Borrower, the Determining Lenders or all Banks, as may be required
hereunder, and the Agent.

         10.14   WAIVER OF JURY TRIAL.  THE PARTIES HERETO WAIVE ALL RIGHT TO
TRIAL BY JURY IN ANY PROCEEDING ENFORCING OR DEFENDING ANY RIGHTS UNDER THIS
AGREEMENT, THE OTHER LOAN DOCUMENTS OR RELATING THERETO.  THE BORROWER
ACKNOWLEDGES THAT THE PROVISIONS OF THIS SECTION HAVE BEEN BARGAINED FOR AND
THAT IT HAS BEEN REPRESENTED BY COUNSEL IN CONNECTION THEREWITH.  THE BORROWER,
THE BANKS AND THE AGENT ALSO WAIVE ANY BOND OR SURETY OR SECURITY UPON SUCH
BOND WHICH MIGHT, BUT FOR THIS WAIVER, BE REQUIRED OF THE AGENT OR ANY OF THE
BANKS.  THE SCOPE OF THIS WAIVER IS INTENDED TO BE ALL-ENCOMPASSING OF ANY AND
ALL DISPUTES THAT MAY BE FILED IN ANY COURT AND THAT RELATE TO THE SUBJECT
MATTER OF THIS TRANSACTION, INCLUDING WITHOUT LIMITATION, CONTRACT CLAIMS, TORT
CLAIMS, BREACH OF DUTY CLAIMS, AND ALL OTHER COMMON LAW AND STATUTORY CLAIMS.
THE BORROWER, THE AGENT AND THE BANKS ACKNOWLEDGE THAT THIS WAIVER IS A
MATERIAL INDUCEMENT TO ENTER INTO A BUSINESS RELATIONSHIP, THAT EACH HAS
ALREADY RELIED ON THE WAIVER IN ENTERING INTO THIS AGREEMENT AND THAT EACH WILL
CONTINUE TO RELY ON THE WAIVER IN ITS RELATED FUTURE DEALINGS.  THE BORROWER,
THE AGENT AND THE BANKS FURTHER WARRANT AND REPRESENT THAT EACH HAS REVIEWED
THIS WAIVER WITH ITS LEGAL COUNSEL, AND THAT EACH KNOWINGLY AND VOLUNTARILY IS
WAIVING ITS JURY TRIAL RIGHTS





                                       76
<PAGE>   82
FOLLOWING CONSULTATION WITH LEGAL COUNSEL.  THIS WAIVER IS IRREVOCABLE, MEANING
THAT IT MAY NOT BE MODIFIED EITHER ORALLY OR IN WRITING, AND THE WAIVER SHALL
APPLY TO ANY SUBSEQUENT AMENDMENTS, RENEWALS, SUPPLEMENTS OR MODIFICATIONS TO
THIS AGREEMENT, THE OTHER LOAN DOCUMENTS, OR TO ANY  OTHER DOCUMENTS OR
AGREEMENTS RELATING TO THE LOAN OR ANY LETTERS OF CREDIT.  IN THE EVENT OF
LITIGATION, THIS AGREEMENT MAY BE FILED AS A WRITTEN CONSENT TO A TRIAL BY THE
COURT UNDER THIS AGREEMENT AND THE OTHER LOAN DOCUMENTS.

         10.15   Headings.  All headings used herein are for the convenience of
the parties only and shall not be used in construing the meaning or intent of
the terms or provisions hereof.

         10.16   Submission to Jurisdiction.  To the extent not expressly
prohibited by law from time to time in effect, the Borrower hereby irrevocably
and unconditionally:

                 (i)      submits for itself and its property in any legal
         action or proceeding relating to any of this Agreement, the Notes and
         the Loan Documents or for recognition and enforcement of any judgment
         in respect thereof, to the non-exclusive general jurisdiction of the
         Courts of Harris County, Texas, the Courts of the United States of
         America for the Southern District of Texas, Houston Division and
         Appellate Courts from any thereof;

                 (ii)     consents that any such action or proceeding may be
         brought in such courts, and waives any objection that it may now or
         hereafter have to the venue of any such action or proceeding in any
         such court or that any such action or proceeding was brought in an
         inconvenient court and agrees not to plead or claim the same;

                 (iii)    agrees that service of process in any such action or
         proceeding may be effected by mailing a copy thereof by registered or
         certified mail (or any substantially similar form of mail), postage
         prepaid, to Borrower at its address set forth in Section 10.03 hereof
         or at such other address of which Agent shall have been notified
         pursuant thereto; and

                (iv)     agrees that nothing herein shall impair the right of
         the Bank to effect service of process in any other manner permitted    
         by law or shall limit the right to sue in any other jurisdiction.

         10.17   Additional Liens.  In the event that an Event of Default has
occurred and is continuing under this Agreement, the Borrower agrees that it
shall, and it shall cause each of the Significant Subsidiaries to grant to the
Agent for the benefit of each of the Banks, a security interest in all of the
accounts and accounts receivable, and all proceeds of each of the foregoing, of
each of such Persons and further agrees to execute and cause to be executed
such financing statements as the Agent may require to perfect the security
interest of the Agent for the benefit of each of the banks in all such
jurisdictions (whether in the United States or abroad) as the





                                       77
<PAGE>   83
Agent may require; and (ii) the Agent is authorized to exercise absolute
dominion and control over any and all lockbox or other controlled accounts
containing proceeds of the accounts of the Borrower or any of its Subsidiaries,
and to apply any such proceeds therein, as the Agent shall determine from time
to time, toward payment of the Obligations, and to block access by the Borrower
or any of its Subsidiaries to any of the proceeds in any such lockbox or other
accounts, until all of the Obligations are fully and finally paid in full.

         10.18   Bank Representations.  Each of the Banks represents that it is
either (i) a corporation organized under the laws of the United States of
America or any state thereof or (ii) it is entitled to complete exemption from
United States withholding tax imposed on or with respect to any payments,
including fees, to be made to it pursuant to this Agreement (A) under
applicable provisions of a tax convention to which the United States of America
is a party or (B) because it is acting through a branch, agency or office in
the United States of America and any payment to be received by it hereunder is
effectively connected with a trade or business in the United States of America.
Each of the Banks that is not a corporation organized under the laws of the
United States of America or any state thereof agrees to provide to the Borrower
and the Agent on the effective date of any sale of an interest in the Loans
(the "Effective Date"), or on the date of its delivery of the Assignment and
Acceptance pursuant to which it becomes one of the Banks, and at such other
times as required by United States law or as the Borrower or the Agent shall
reasonably request, two accurate and complete original signed copies of either
(a) Internal Revenue Service Form 4224 (or successor form) certifying that all
payments to be made to it hereunder will be effectively connected to a United
States trade or business (the "Form 4224 Certification") or (B) Internal
Revenue Service Form 1001 (or successor form) certifying that it is entitled to
the benefit of a provision of a tax convention to which the United States of
America is a party which completely exempts from United States withholding tax
all payments to be made to it hereunder (the "Form 1001 Certification").  In
addition, each Bank agrees that if it previously filed a Form 4224
Certification it will deliver to the Borrower and the Agent a new Form 4224
Certification prior to the first payment date occurring in each of its
subsequent taxable years; and if it previously filed a Form 1001 Certification,
it will deliver to the Borrower and the Agent a new certification prior to the
first payment date falling in the third year following the previous filing of
such certification.  Each of the Banks also agrees to deliver to the Borrower
and the Agent such other or supplemental forms as may at any time be required
as a result of changes in applicable law or regulations in order to confirm or
maintain in effect its entitlement to exemption from United States withholding
tax on any payments hereunder, provided that the circumstances of the Banks at
the relevant time and applicable laws permit it to do so.  If one of the Banks
determines, as a result of any change in either (i) applicable law, regulation
or treaty, or in any official interpretation thereof or (ii) its circumstances,
that it is unable to submit any form or certificate that it is obligated to
submit pursuant to this Section, or that it is required to withdraw or cancel
any such form or certificate previously submitted, it shall promptly notify the
Borrower and the Agent of such fact.  If any of the Banks are organized under
the laws of a jurisdiction outside the United States of America, unless the
Borrower and the Agent have received a Form 1001 Certification or Form 4224
Certification satisfactory to them indicating that all payments to be made to
such Banks hereunder are not subject to United States withholding tax, the
Borrower shall withhold taxes from such payments at the applicable statutory
rate, provided that such withholding shall not increase the amount of payments
for the account of such Banks to be made by the Borrower





                                       78
<PAGE>   84
pursuant to Subsection 2.18.  Each of the Banks agrees to indemnify and hold
harmless from any United States taxes, penalties, interest and other expenses,
costs and losses incurred or payable by (i) the Agent as a result of such
Bank's failure to submit any form or certificate that it is required to provide
pursuant to this Section or (ii) the Borrower or the Agent as a result of their
reliance on any such form or certificate which it has provided to them pursuant
to this Section.

         10.19   Indemnification.  (a) In addition to any liability that the
Borrower might otherwise have, the Borrower does hereby indemnify and agree to
hold harmless the Agent, each of the Banks and their respective "controlling
persons" (within the meaning of Section 20(a) of the Securities Exchange Act of
1934, as amended), officers, directors, shareholders, employees, agents,
insurers and assigns from and against any and all liabilities, obligations,
losses, damages, penalties, actions, judgments, suits, costs expenses or
disbursements of any kind or nature whatsoever which may be imposed on,
incurred by, or asserted against the Agent or any of the Banks by reason of or
in connection with (i) any actual or proposed use by the Borrower of the
proceeds of any extension of credit by the Banks hereunder, (ii) the execution
and delivery or transfer of, or payment under, any Letter of Credit, (iii) any
of the Loan Documents or any action taken or omitted to be taken by Agent
hereunder, and (iv) any investigation, litigation, or other proceeding
(including any threatened investigation or proceeding) relating to the
foregoing, and the Borrower shall reimburse the Agent and each of the Banks
upon demand for any such expenses incurred in connection with any such
investigation or proceeding; but excluding any such losses, liabilities,
claims, damages or expenses incurred by reason of the gross negligence or
willful misconduct of the Person to be indemnified.

         (b)     WITHOUT LIMITING ANY PROVISION OF THIS AGREEMENT, IT IS THE
EXPRESS INTENTION OF THE PARTIES HERETO THAT EACH PERSON TO BE INDEMNIFIED
UNDER THIS SECTION 10.19 SHALL BE INDEMNIFIED AND HELD HARMLESS AGAINST ANY AND
ALL LOSSES, LIABILITIES, CLAIMS OR DAMAGES ARISING OUT OF OR RESULTING FROM THE
SOLE OR CONTRIBUTORY ORDINARY NEGLIGENCE OR SUCH PERSON, BUT SUCH INDEMNITEE
SHALL NOT BE INDEMNIFIED WITH RESPECT TO THE GROSS NEGLIGENCE OR WILLFUL
MISCONDUCT OF SUCH PERSON.  Without prejudice to the survival of any other
obligations of the Borrower hereunder and the Notes, the Obligations of the
Borrower under this Section 10.19 shall survive the termination of this
Agreement and the payment or assignment of any of the Notes.





                                       79
<PAGE>   85
         IN WITNESS WHEREOF, the parties have caused this Agreement to be duly
executed and delivered by their proper and duly authorized officers as of the
day and year first above written.

                              BORROWER:
                              
                              NOBLE DRILLING CORPORATION
                              
                              
                              By:         /s/   BYRON L. WELLIVER
                                  ______________________________________________
                                     Byron L. Welliver, Sr. Vice President -
                                           Finance and Treasurer
                              
                              AGENT:
                              
                              FIRST INTERSTATE BANK OF TEXAS, N. A.,
                                 as Agent
                              
                              
                              By:         /s/  CAROL D. BIRKOFER
                                  ______________________________________________
                                    Carol D. Birkofer, Assistant Vice President

                              
Specified Percentage:         BANKS:
50% (resulting in a total     
commitment of $15,000,000)    FIRST INTERSTATE BANK OF TEXAS, N. A.
                              
                              
                              By:         /s/  CAROL D. BIRKOFER
                                  ______________________________________________
                                    Carol D. Birkofer, Assistant Vice President
                              
                              Applicable Lending Office for Base Rate Advances
                              
                              1000 Louisiana Street, 3rd Floor
                              Houston, Texas  77002
                              Telecopy No. (713) 250-7029

                              Applicable Lending Office for Eurodollar Advances

                              1000 Louisiana Street, 3rd Floor
                              Houston, Texas  77002
                              Telecopy No. (713) 250-7029





                                       80
<PAGE>   86
Specified Percentage:         CREDIT LYONNAIS CAYMAN ISLAND BRANCH
50% (resulting in a total
commitment of $15,000,000)
                              By:         /s/  XAVIER RATOUIS
                                  _________________________________________
                              Print Name:      Xavier Ratouis
                              Print Title:  Authorized signature
                                                              

                              Applicable Lending Office for Base Rate Advances

                              c/o Credit Lyonnais Houston Representative Office
                              1000 Louisiana, Suite 5360
                              Houston, Texas  77002

                              Applicable Lending Office for Eurodollar Advances

                              c/o Credit Lyonnais Houston Representative Office
                              1000 Louisiana, Suite 5360
                              Houston, Texas  77002
                                    




                                       81
<PAGE>   87

                          NOBLE DRILLING CORPORATION

                                  SCHEDULE 1
                      LIENS IN EXISTENCE AT CLOSING DATE


LIENS IN FAVOR OF ROYAL BANK OF CANADA:

      Noble Drilling (Canada) Ltd. -- U.S. $1,000,000 line of credit:

           Following rigs:

            Rig           Description     
           -----      ---------------------------------

           N134       Lee C. Moore/National 1320 UE
           GD501      Lee C. Moore/Gardner Denver GD500
           GD502      Dreco/Gardner Denver GD500
           E1501      Dreco/Continential Emsco C-1
           E1502      Lee C. Moore/Continental Emsco C-1

           Land and buildings in Nisku Industrial Park in Edmonton

           Assignment of accounts receivable of Noble Drilling (Canada) Ltd.


LIEN IN FAVOR OF GUARANTY BANK & TRUST COMPANY OF MORGAN CITY:
DEBTOR: NOBLE DRILLING COMPANY

     Ten (10) acre tract adjoining Bayou Black in Terrebone Parish,
     Louisiana, together with a shop building.

    
LIEN IN FAVOR OF UNITED STATES GOVERNMENT:
DEBTOR: NN-1 LIMITED PARTNERSHIP

     NN-1, jackup rig


LIEN IN FAVOR OF BOISE CASCADE CORPORATION:
DEBTOR: TRITON TOOL AND SUPPLY, INC.

     17.235 acre tract and associated buildings located in Harris
     County, Texas.

LIEN IN FAVOR OF NATIONSBANK OF TEXAS N.A.; MARINE MIDLAND BANK, N.A.;
  BANK OF AMERICA NATIONAL TRUST AND SAVINGS ASSOCIATION; AND NORWEST       
  BANK MINNESOTA, NATIONAL ASSOCIATION:
LETTERS OF CREDIT ISSUED BY NOBLE (GULF OF MEXICO) INC.

     Joe Alford (Portal 201)

     Lester Pettus (Portal 202)

                                    
<PAGE>   88
                        NOBLE DRILLING CORPORATION

                               SCHEDULE 3.10
                 INDEBTEDNESS OUTSTANDING AT CLOSING DATE


<TABLE>
<CAPTION>
                                                                                                   (U.S. $000's)
                                                                                   ----------------------------------------------
                                                  Interest            Interest        Amount          Amount Due          Amount
         Loan Description                           Basis               Rate       Outstanding     within One Year      Available
         ----------------                         --------            --------     -----------     --------------       ---------
<S>                                             <C>                    <C>          <C>               <C>               <C>
9 1/4% Senior Notes Due 2003                     
    Obligor: Noble Drilling Company                9.25%                9.25%       $125,000               0                 0

Royal Bank of Canada
  Canadian Line of Credit                       RB Prime +.75           7.50%              0               0            $1,000(1)
    Obligor: Noble Drilling (Canada) Ltd.     

U.S. Government -- Guaranteed Ship                 8.95%                8.95%          2,586          $  520                 0
  Financing Sinking Fund Bonds
    Obligor: NN -- 1 Limited Partnership

Guaranty Bank & Trust Company                    Prime +1.00            8.25%             98              26                 0
  of Morgan City
    Obligor: Noble Drilling Corporation

Boise Cascade Corporation                          8.25%                8.25%          1,571           1,571                 0
    Obiligor: Triton Tool and Supply, Inc. 

Joseph E. Beall
    Obligor: Noble Drilling Corporation      NationsBank Prime         7.25%           3,938           3,938                 0

George H. Bruce
    Obligor: Noble Drilliing Corporation     NationsBank Prime         7.25%              62              62                 0
                                                                                    --------          ------            ------
Total                                                                               $133,255          $6,117            $1,000
                                                                                    --------          ------            ------
                                                                                    --------          ------            ------

</TABLE>

(1) Margined to 75% of receivables outstanding less than ninety days.

GUARANTEES

1. Guarantee by Noble Drilling International Inc. in favor of Royal Bank of
   Canada for Noble Drilling (Canada) Ltd. U.S. $1,000,000 credit line.

2. Guarantees by Noble Drilling (U.K.) Limited and Noble Drilling (Canada) Ltd.
   in favor of Royal Bank of Canada for Resolute Insurance Group Ltd. 
   U.S. $683,009 letter of credit facility.

LETTERS OF CREDIT

1. Resolute Insurance Group Ltd. U.S. $683,009 letter of credit in favor of
   Insurance Company of North America and/or INA.

2. Noble International Limited U.S. $937,200 letter of credit in favor of Pemex
   Exploration and Production.

3. Noble Drilling International Inc. and/or Noble International Limited 
   U.S. $100,000 and U.S. $200,000 letters of credit in favor of Qatar General
   Petroleum Corporation.

4. Noble (Gulf of Mexico) Inc. $6,411,554 and U.S. $5,803,268 letters of credit
   in favor of Atlantic Ritchfield Company.
<PAGE>   89
                          NOBLE DRILLING CORPORATION

                                SCHEDULE 3.12
                        ERISA MATTERS AT CLOSING DATE


        The following table sets forth disclosure of ERISA matters for Noble
Drilling Corporation as of the closing date:

                             Nothing to disclose.

<PAGE>   90
 
                           NOBLE DRILLING CORPORATION
 
                                 SCHEDULE 3.14
                            LISTING OF SUBSIDIARIES
 
     The following table sets forth the direct and indirect subsidiaries of
Noble Drilling Corporation as of the closing date:
 
<TABLE>
<CAPTION>
                            SUBSIDIARY                                   INCORPORATION
- ---------------------------------------------------------------------------------------------
<S>                                                                <C>
NN-1 Limited Partnership(1)                                        Texas
Noble Properties Inc.(2)                                           Oklahoma
Noble Drilling International Inc.                                  Delaware
Noble Drilling (U.S.) Inc.(2)                                      Delaware
Noble Drilling Services Inc.(2)                                    Delaware
Noble Production Management Inc.(2)                                Delaware
Noble Drilling (West Africa) Inc.(2)                               Delaware
Noble Drilling (Mexico) Inc.(3)                                    Delaware
Noble (Gulf of Mexico) Inc.(3)                                     Delaware
Mexico Offshore Drilling Services Inc.(3)                          Delaware
Bawden Drilling Inc.(4)                                            Delaware
Noble Offshore Corporation(2)                                      Delaware
Noble Drilling (Canada) Ltd.(4)                                    Alberta
Drillhawk Service & Supply Ltd.(4)                                 Alberta
Noble Offshore Ltd.(4)                                             Alberta
372733 Alberta Inc.(4)                                             Alberta
Noble International Limited(4)                                     Cayman Islands
Noble Drilling International Ltd.(4)                               Bermuda
Noble Drilling (Europe) Ltd.(4)                                    Bermuda
Noble Holdings Limited(4)                                          Bermuda
Interco Oilfield Supply Ltd.(4)                                    Bermuda
International Directional Services Ltd.(4)                         Bermuda
Noble International Services Ltd.(4)                               Bermuda
Resolute Insurance Group Ltd.(4)                                   Bermuda
Bawden Drilling International Ltd.(4)                              Bermuda
Noble Drilling (UK) Limited(4)                                     Scotland
Noble Offshore Services Ltd.(4)                                    Scotland
Noble Engineering Services Ltd.(4)                                 Scotland
Noble Drilling (Malaysia) SDN. BHD(6)                              Malaysia
Noble Services SDN. BHD(4)                                         Brunei
Noble Enterprises Limited(4)                                       Cayman Islands
Noble Drilling Limited(4)                                          Cayman Islands
Noble Drilling International Services PTE Ltd.(4)                  Singapore
Noble Drilling Arabia Ltd.(4)                                      Saudia Arabia
Bawden Drilling (Guatemala) Ltd.(4)                                Bermuda
Noble Drilling (West Africa) Ltd.(5)                               Bermuda
Noble Drilling (Nigeria) Ltd.(5)                                   Nigeria
Noble Drilling de Venezuela C.A.(4)                                Venezuela
Triton Engineering Services Company(2)                             Texas
Triton USA, Inc.(7)                                                Delaware
Triton International, Inc.(7)                                      Delaware
Triton Tool and Supply, Inc.(7)                                    Texas
Triton International Limited(7)                                    Cayman Islands
Triton Engineering Services Company, S.A.(7)                       Texas
Triton Engineering Services Company Limited(7)                     UK Registered Company
Triton Turn-Key, Inc.(7)                                           Texas
Threadneedle Oil Company(7)                                        Texas
Triton/Faja de Oro Joint Venture(8)                                Mexico Registered Company
</TABLE>
 
- ---------------
 
(1) General Partnership interest owned 50% by Noble Drilling Corporation. Noble
    Drilling Corporation's sharing percentage in Noble-National Joint Ventures'
    distributions from operations is 90 percent.
(2) 100% owned by Noble Drilling Corporation.
(3) 100% direct or indirect subsidiary of Noble Drilling (U.S.) Inc.
(4) Direct or indirect subsidiary of Noble Drilling International Inc.
(5) 100% owned by Noble Drilling (West Africa) Inc.
(6) 70% owned indirectly by Noble Drilling International Inc.
(7) 100% owned by Triton Energy Services Company.
(8) Joint venture owned 50% by Triton Engineering Services Company.
<PAGE>   91
 
                           NOBLE DRILLING CORPORATION
 
                                 SCHEDULE 5.17
        CERTAIN ENCUMBRANCES OR RESTRICTIONS CONTAINED IN ANY AGREEMENT
                 OR INSTRUMENT AND EXISTING ON THE CLOSING DATE
 
     Limited Partnership Agreement dated as of January 16, 1992, between Noble
Drilling Corporation and National Enerdrill Corporation relating to NN -- 1
Limited Partnership, a Texas limited partnership.
<PAGE>   92
                                   EXHIBIT A

                          FORM OF REVOLVING CREDIT NOTE


$_____________                                                    June __, 1994


        NOBLE DRILLING CORPORATION, a Delaware corporation (the "Borrower"),
for value received, promises to pay to the order of ___________________________
(the "Bank"), at the offices of FIRST INTERSTATE BANK OF TEXAS, N.A. (the 
"Agent"), at 1000 Louisiana, 3rd Floor, Houston, Texas 77002, the principal sum
of _______________________________________________________________________
DOLLARS ($________________), or such lesser amount as shall equal the aggregate
unpaid principal amount of the Revolving Loans made by Bank hereunder to the
Borrower under the Credit Agreement, as hereafter defined, in lawful money of
the United States of America and in immediately available funds, on the dates
and in the principal amounts provided in the Credit Agreement referred to
below, and to pay interest on the unpaid principal amount as provided in the
Credit Agreement for such Revolving Loans made by the Bank to the Borrower
under the Credit Agreement, at such office, in like money and funds, for the
period commencing on the date of each such Revolving Loan until such Revolving
Loan shall be paid in full, at the rates per annum and on the dates provided in
the Credit Agreement.

         In addition to and cumulative of any payments required to be made
against this Note pursuant to the Credit Agreement, this Note, including all
principal and accrued interest then unpaid shall be due and payable on June __,
1996, its final maturity.  All payments shall be applied first to accrued
unpaid interest and the balance to principal, except as otherwise expressly
provided in the Credit Agreement.  Prepayments on this Note shall be applied in
the manner set forth in the Credit Agreement.

         This Note is one of the Notes referred to in the Credit Agreement
dated as of the ___ day of June, 1994, by and among the Borrower and First
Interstate Bank of Texas, N. A., individually, and as Agent, and the financial
institutions party thereto (including the Bank) (such Credit Agreement,
together with all amendments or supplements thereto, being the "Credit
Agreement").  This Note evidences the Revolving Loans made by the Bank
thereunder and shall be governed by the Credit Agreement.  Capitalized terms
used in this Note and not defined in this Note, but which are defined in the
Credit Agreement, have the respective meanings herein as are assigned to them
in the Credit Agreement.

        This Note is a revolving credit note and it is contemplated that by
reason of prepayments hereon there may be times when no indebtedness is owing
hereunder; but 





                                                _______________________________
                                                    Initials for Identification
                                      A-1
<PAGE>   93
notwithstanding such occurrence, this Note shall remain valid and shall be in
full force and effect as to each principal advance made hereunder subsequent to
each such occurrence.

         The Bank is hereby authorized by the Borrower to endorse on Schedule A
(or a continuation thereof) attached to this Note, the Type of each Revolving
Loan, the amount and date of each payment or prepayment of principal of each
such Revolving Loan received by the Bank and the Interest Periods and interest
rates applicable to each Revolving Loan, provided that any failure by the Bank
to make any such endorsement shall not affect the obligations of the Borrower
under the Credit Agreement or under this Note in respect of such Revolving
Credit Loans.

        It is the intent of the Bank and the Borrower in the execution and
performance of this Note to remain in strict compliance with Applicable Law
from time to time in effect.  In furtherance thereof, the Bank and the Borrower
stipulate and agree that none of the terms and provisions contained in this
Note, or in the Credit Agreement or any document securing or otherwise relating
to this Note, shall ever be construed to create a contract to pay for the use,
forbearance or detention of money with interest at a rate or in an amount in
excess of the maximum rate or amount of interest permitted to be charged under
Applicable Law.  For purposes of this Note "interest" shall include the
aggregate of all charges which constitutes interest under Applicable Law that
are contracted for, charged, reserved, received or paid under this Note.  The
Borrower shall never be required to pay unearned interest and shall never be
required to pay interest at a rate or in an amount in excess of the maximum
rate or amount or interest that may be lawfully charged under Applicable Law,
and the provisions of this paragraph shall control over all other provisions of
this Note, the Credit Agreement and any other instrument pertaining to or
securing this Note, which may be in apparent conflict herewith.  If this Note
is prepaid, or if the maturity of this Note is accelerated for any reason, or
if under any other contingency the effective rate or amount of interest which
would otherwise be payable under this Note would exceed the maximum rate or
amount of interest the Bank or the holder of this Note is allowed by Applicable
Law to charge, contract for, take, reserve or receive, or in the event that the
Bank or any holder of this Note shall charge, contract for, take, reserve or
receive monies deemed to constitute interest which would, in the absence of
this provision, increase the effective rate or amount of interest payable under
this Note to a rate or amount in excess of that permitted to be charged,
contracted for, taken, reserved or received under Applicable Law then in
effect, then the principal amount of this Note or the amount of interest which
would otherwise be payable under this Note or both shall be reduced to the
amount allowed under Applicable Law as now or hereinafter construed by the
courts having jurisdiction, and all such monies so charged, contracted for,
taken, reserved or received are deemed to constitute interest in excess of the
maximum rate or maximum amount of interest permitted by Applicable Law shall
immediately be returned to or credited to the account of the Borrower upon such
determination.  The Bank and the Borrower further stipulate and agree that
without limitation of the foregoing, all calculations of the rate or the amount
of interest contracted for, charged, taken, reserved or received under this
Note which 



                                                                 
                                                 _______________________________
                                                     Initials for Identification
                                     A-2
<PAGE>   94
are made for the purpose of determining whether such rate or amount exceeds the
maximum lawful rate or amount, shall be made to the extent permitted by 
Applicable Law, by amortizing, prorating, allocating and spreading during the 
period of the full stated term of this Note, all interest at any time 
contracted for, charged, taken, reserved or received from the Borrower or
otherwise by the Bank or the holders of this Note.

         The Borrower and all sureties, endorsers and guarantors of this Note
waive demand, presentment for payment, notice of nonpayment, protest, notice of
protest, notice of intent to accelerate maturity, notice of acceleration of
maturity and all other notices, filing of suit and diligence in collecting this
Note or enforcing any of the security herefor, and agree to any substitution,
exchange or release of any such security or guaranty, release of any party
primarily or secondarily liable hereon and further agree that it will not be
necessary for any holder hereof, in order to enforce payment of this Note by
such holder, to first institute suit or exhaust its remedies against any
security herefor or guarantor hereof, and consent to any one or more extensions
or postponements of time of payment of this Note on any terms or any other
indulgences with respect hereto, without notice thereof to any of them.  Each
such person agrees that his, her or its liability on or with respect to this
Note shall not be affected by any release of or change in any guaranty or
security at any time existing or by any failure to perfect or maintain
perfection of any lien against or security interest in any such security or the
partial or complete enforceability of any guaranty or other surety obligation,
in each case in whole or in part, with or without notice and before or after
maturity.

         The Credit Agreement, as at any time amended, provides for the
acceleration of the maturity of this Note upon the occurrence of certain events
and for prepayment of Revolving Loans upon the terms and conditions specified
therein.  Reference is hereby made to the Credit Agreement for all other
pertinent purposes.

         This Note is issued pursuant to and is entitled to the benefits of the
Credit Agreement.

         THIS NOTE SHALL BE CONSTRUED IN ACCORDANCE WITH AND BE GOVERNED BY THE
INTERNAL LAWS OF THE STATE OF TEXAS AND THE UNITED STATES OF AMERICA FROM TIME
TO TIME IN EFFECT.

                                        NOBLE DRILLING CORPORATION



                                        By:____________________________________
                                        Byron L. Welliver, Senior Vice
                                        President - Finance and Treasurer




                                              _________________________________
                                                    Initials for Identification
                                    A-3

<PAGE>   95

                                   EXHIBIT C

                                    FORM OF

                           ASSIGNMENT AND ACCEPTANCE

                       Dated:  __________________, 199___


         Reference is made to the Credit Agreement dated as of June __, 1994
(as restated, amended, modified, supplemented and in effect from time to time,
the "Credit Agreement"), between NOBLE DRILLING CORPORATION, a Delaware
corporation ("Borrower"), FIRST INTERSTATE BANK OF TEXAS, N.A., individually,
as one of the Banks and as agent, and the financial institutions parties
thereto (the "Lenders").  Capitalized terms used herein and not otherwise
defined shall have the meanings assigned to such terms in the Credit Agreement.
This Assignment and Acceptance, between the Assignor (as defined and set forth
on Schedule I hereto and made a part hereof) and the Assignee (as defined and
set forth on Schedule I hereto and made a part hereof) is dated as of the
Effective date (as set forth on Schedule I hereto and made a part hereof).

         1.      The Assignor hereby irrevocably sells and assigns to the
Assignee without recourse to the Assignor, and the Assignee hereby irrevocably
purchases and assumes from the Assignor without recourse to the Assignor, as of
the Effective Date, an undivided interest (the "Assigned Interest") in and to
all the Assignor's rights and obligations under the Credit Agreement respecting
the credit facilities contained in the Credit Agreement as set forth on
Schedule I (herein referred to as the "Assigned Interests"), in a principal
amount for each Loan, and in and to Assignor's participation interests in the
Letters of Credit and unpaid Reimbursement Obligations, as set forth on
Schedule I.  The purchase hereby of the Assignee Interest by the Assignee
constitutes a purchase of a participation interest in each Letter of credit
outstanding on the date hereof, and in all outstanding Reimbursement
Obligations then due and payable by Borrower, in an amount equal to such
Assignee's Specified Percentage (as set forth on Schedule I attached hereto).

         2.      The assignor (i) represents and warrants that it owns the
Assigned Interest free and clear from any lien or adverse claim; (ii) other
than the representation and warranty set forth in clause (i) above, makes no
representation or warranty and assumes no responsibility with respect to any
statements, warranties or representations made in or in connection with the
Credit Agreement or any other instrument, document or agreement delivered in
connection therewith, or the execution, legality, validity, enforceability,
genuineness, sufficiency or value of the Credit Agreement, or any other
instrument or document furnished pursuant thereto, other than that it is the
legal and beneficial owner of the interest being assigned by it hereunder and
that such interest is fee and clear of any adverse claim; (iii) makes no
representation or warranty and assumes no responsibility with respect to the
financial condition of the Borrower or its Subsidiaries or the performance or
observance by the Borrower or its Subsidiaries of any





                                      C-1
<PAGE>   96
of its respective obligations under the Credit Agreement, or any other
instrument or document furnished pursuant thereto; and (iv) attaches the Notes
held by it evidencing the Assigned Loans and requests that the Agent exchange
such Note(s) for a new Note or Notes payable to the Assignor (if the Assignor
has retained any interest in the Assigned Loans) and new Notes payable to the
Assignee in the respective amounts which reflect the assignment being made
hereby (and after giving effect to any other assignments which have become
effective on the Effective Date).

         3.      The Assignee (i) represents and warrants that it is legally
authorized to enter into this Assignment and Acceptance and that it is an
Eligible Assignee under the Credit Agreement; (ii) confirmed that it has
received a copy of the Credit Agreement, together with copies of the financial
statements referred to in Section 3.09 or if later, the most recent financial
statements delivered pursuant to Section 4.01 thereof, and such other documents
and information as it has deemed appropriate to make its own credit analysis;
(iii) agrees that it will, independently and without reliance upon the Agent,
the Assignor or any other Lender and based on such documents and information as
it shall deem appropriate at the time, continue to make its own credit
decisions in taking or not taking action under the Credit Agreement; (iv)
appoints and authorizes the Agent to take such to take such action as agent on
its behalf and to exercise such powers under the Credit Agreement as are
delegated to the Agent by the terms thereof, together with such powers as are
reasonably incidental thereto; (v) agrees that it will be bound by the
provisions of the Credit Agreement and will perform in accordance with its
terms all the obligations which by the terms of the Credit Agreement are
required to be performed by it as a Lender and hereby makes the Lender
representations set forth in Section 10.18 of the Credit Agreement; and (vi) if
the Assignee is organized under the laws of a jurisdiction outside the United
States, attaches the forms prescribed by the Internal Revenue Service of the
United States and required pursuant to Section 10.18 of the Credit Agreement
certifying as to the Assignee's exemption from United States withholding taxes
with respect to all payments to be made to the Assignee under the Credit
Agreement or such other documents as are necessary to indicate that all such
payments are subject to such tax at a rate reduced by an applicable tax treaty.

         4.      Following the execution of this Assignment and Acceptance, it
will be delivered to the Agent and the Borrower for acceptance by each of them
and recording by the Agent pursuant to Section 10.07 of the Credit Agreement,
effective as of the Effective Date (which Effective Date shall, unless
otherwise agreed to by the Agent, be at least five Business Days after the
execution of this Assignment and Acceptance).

         5.      Upon acceptance and recording by the Agent, all payments under
the Credit Agreement in respect of the Assigned Interest (including without
limitation, all payments of principal, interest and fees with respect thereto)
for the period up to, but not including the Effective Date, shall be made to
the Assignor, and for the period from and after the Effective Date shall be
made to the Assignee.  Assignor and Assignee hereby agree that if Assignor
receives any of the payments referred to in the preceding sentence which should
have been





                                      C-2
<PAGE>   97
made to Assignee, or if Assignee receives any of the payments referred to in
the previous sentence which should have been made to Assignor, such payments
shall promptly be paid by Assignor to Assignee, or by Assignee to Assignor, as
the case may be, in full.

         6.      From and after the Effective Date, (i) the Assignee shall be a
party to the Credit Agreement and, to the extent provided in this Assignment
and Acceptance and Section 10.07 of the Credit Agreement, have the rights and
obligations of one of the Banks thereunder, and (ii) the Assignor shall, to the
extent provided in this Assignment and Acceptance and Section 10.07 of the
Credit Agreement, relinquish its rights and be released from its rights and be
released from its obligations under the Credit Agreement.

         7.      THIS ASSIGNMENT AND ACCEPTANCE SHALL BE GOVERNED BY, AND
CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF TEXAS.

         IN WITNESS WHEREOF, the parties hereto have caused this assignment and
Acceptance to be executed by their respective duly authorized officers on
Schedule I hereto.

                                        ________________________________________
                                                      as Assignor


                                        By:_____________________________________
                                        Print Name:_____________________________
                                        Print Title:____________________________


                                        ________________________________________
                                                      as Assignee


                                        By:_____________________________________
                                        Print Name:_____________________________
                                        Print Title:____________________________


                                        AGREED AND CONSENTED TO:

                                        NOBLE DRILLING CORPORATION


                                        By:_____________________________________
                                        Print Name:_____________________________
                                        Print Title:____________________________






                                      C-3
<PAGE>   98

                                        FIRST INTERSTATE BANK OF TEXAS, N.A.,


                                        By:_____________________________________
                                        Print Name:_____________________________
                                        Print Title:____________________________







                                      C-4
<PAGE>   99
                    SCHEDULE I TO ASSIGNMENT AND ACCEPTANCE
                        RESPECTING THE CREDIT AGREEMENT,
                        DATED AS OF JUNE __, 1994 AMONG
                         NOBLE DRILLING CORPORATION AND
                     FIRST INTERSTATE BANK OF TEXAS, N.A.,
                        AS AGENT AND AS AN ISSUING BANK,
                          AND THE BANKS PARTY THERETO


Assignor:_______________________________________

Assignee:_______________________________________

Effective Date of Assignment:___________________________________

<TABLE>
<CAPTION>
                                                                                  Specified Percentage
                                                                                (to at least 8 decimals)
                                                                                shown as a percentage of
              Assigned                                   Total Amount              aggregate original
             Obligations                                   Assigned                 principal amount
             -----------                                   --------                   of all Banks  
                                                                                      ------------
 <S>                                                 <C>                                 <C>
 Revolving Credit Loans (sum of                      $_______________.__                 _____%
 Commitment for Loans and
 outstanding amounts)

 Participation in Outstanding                        $_______________.__                 _____%
 Letters of Credit and Unpaid
 Reimbursement Obligations
</TABLE>


 Assignee's Base Rate                    Address for Notice:
 Lending Office

 ___________________________________     ______________________________________
 ___________________________________     ______________________________________
 ___________________________________     ______________________________________
 ___________________________________     ______________________________________
 ___________________________________     ______________________________________
 ___________________________________     ______________________________________
                                    




                                      C-5
<PAGE>   100
 Assignee's Eurodollar                      Telex No.:__________________________
 Lending Office
                                            Telecopy No.:_______________________

 ________________________________________
 ________________________________________
 ________________________________________
 




                                      C-6
<PAGE>   101

                                   EXHIBIT D


                               GUARANTY AGREEMENT

         THIS GUARANTY AGREEMENT ("Guaranty") is executed by each of the
corporations signatory hereto (collectively, the "Guarantors", and each
individually a "Guarantor"), in favor of First Interstate Bank of Texas, N.A.,
a national banking association in its individual capacity and as agent for the
Banks party to that certain Credit Agreement dated as of June __, 1994 between
Noble Drilling Corporation, a Delaware corporation ("Borrower") and such Banks.

         WHEREAS, each Guarantor hereby acknowledges and agrees that the
financial accommodations to be made to Borrower pursuant to the Credit
Agreement (as hereinafter defined) will materially benefit Borrower and each
Guarantor, and in recognition of this fact, each Guarantor desires to secure
the payment of any and all indebtedness, obligations and liabilities to Agent
or to Banks now, heretofore or hereafter arising under, or in connection with
the Guaranteed Indebtedness (as hereinafter defined);

         WHEREAS, the Banks are not willing to make the loans under the Credit
Agreement or otherwise extend credit to Borrower unless the Guarantors
unconditionally and irrevocably guarantee payment of all present and future
indebtedness and obligations of the Borrower to the Banks,

         NOW, THEREFORE, in consideration of credit and financial
accommodations extended or to be extended to the Borrower, by and for other
good, fair and valuable considerations and reasonably equivalent value, the
receipt and sufficiency of which are hereby acknowledged, the Guarantors hereby
agree as follows:


                                   ARTICLE I

                          NATURE AND SCOPE OF GUARANTY

         Section 1.01.  Guaranty of Obligation.  Guarantors hereby irrevocably,
jointly and severally, and unconditionally guarantee to the Agent and to each
of the Banks and their respective successors and assigns, when due (and
howsoever such due date or maturity shall arise), (i) the due and punctual
payment of the Guaranteed Debt as that term is hereinafter defined; and (ii)
the performance of all other obligations, liabilities, covenants and agreements
under the Credit Agreement.  Guarantors hereby irrevocably and unconditionally
covenant and agree that each is jointly and severally liable for the Guaranteed
Debt as primary obligor.





                                      D-1
<PAGE>   102
         Section 1.02.  Definitions.

         (a)     As used herein, the following capitalized terms shall have the
following meanings:

         "Agent" means First Interstate Bank of Texas, N.A., as agent for the
Banks party to the Credit Agreement, or such Person as is successor thereto as
"agent" for the Banks.

         "Banks" means each of the banks party to the Credit Agreement and such
banks' respective successors and assigns.

         "Borrower" means Noble Drilling Corporation, a Delaware corporation.

         "Credit Agreement" means that certain Credit Agreement dated as of
June __, 1994, by and among Borrower, the Agent, and the banks party thereto,
which provides for a revolving credit facility of up to $25,000,000 and for the
issuance of Letters of Credit in the face amount of up to $5,000,000.

         "Debtor Laws" means any federal, or state bankruptcy, insolvency,
reorganization, moratorium, fraudulent transfer, fraudulent conveyance,
preferential transfer or similar laws and judicial decisions, relating to or
affecting the enforcement of creditors' rights generally.

         "Guaranteed Debt" means:

         (a)     all principal, interest, reasonable attorneys' fees,
commitment fees, other fees, reimbursement obligations arising in connection
with letters of credit issued in connection with the Credit Agreement,
liabilities for costs and expenses and other indebtedness, obligations and
liabilities of Borrower to the Agent or to the Banks at any time arising under
the Credit Agreement, including, without limitation, all indebtedness,
obligations and liabilities arising under the Notes and each and every
scheduled payment of principal and/or interest as provided therein, and under
any renewals, extensions, increases, refinancings and rearrangements of the
Notes.

         (b)  all post petition interest on indebtedness, obligations and
liabilities of Borrower described in clause (a) above in the event of
bankruptcy of Borrower, or any of the Guarantors; and

         (c)     all costs, expenses and fees, including, without limitation,
court costs and reasonable attorneys' fees, arising in connection with the
enforcement or collection (whether or not any proceeding is commenced in
connection therewith) of any or all amounts, indebtedness, obligations and
liabilities of Borrower to the Agent or to the Banks described in clauses (a)
and (b) above.





                                      D-2
<PAGE>   103
         "Notes" means each of the revolving notes made by Borrower to the
order of each of the Banks, executed pursuant to the Credit Agreement.

         (b)     Capitalized items used and not otherwise defined herein shall
have the meanings set forth therefor in the Credit Agreement.

         Section 1.03.  Indebtedness Not Reduced by Offset.  The Guaranteed Debt
shall not be reduced, discharged or released because or by reason of any
existing or future offset, claim or defense of Borrower or any other Person,
against Agent or Banks or against payment of the Guaranteed Debt, whether such
offset, claim or defense arises in connection with the Guaranteed Debt (or the
transactions creating the Guaranteed Debt) or otherwise.  Without limiting the
foregoing or the Guarantors' liability hereunder, to the extent that the Agent
or any of the Banks advances funds or extends credit to Borrower, and does not
receive payments or benefits thereon in the amounts and at the time required or
provided by applicable agreements or Laws, each of the Guarantors is absolutely
liable to make such payments to (and confer such benefits on) each of the Banks
and the Agent, on a timely basis.

         Section 1.04.  "Borrower" to Include New Corporations.  The term
"Borrower" as used herein shall include any successor corporation, partnership,
association or other entity formed as a result of any reformation by, or merger
or reorganization of, Noble Drilling Corporation, a Delaware corporation.

         Section 1.05.  Payment by Guarantors.  If all or any part of the
Guaranteed Debt shall not be punctually paid when due, whether at maturity or
earlier by acceleration or otherwise, Guarantors shall, immediately upon demand
by the Agent or the Banks, and without presentment, protest, notice of protest,
notice of non-payment, notice of intention to accelerate, notice of
acceleration or any other notice whatsoever, pay in lawful money of the United
States of America, the amount due on the Guaranteed Debt to Agent at Agent's
principal office in Houston, Texas.  Such demand(s) may be made at any time
coincident with or after the time for payment of all or part of the Guaranteed
Debt is due, but not punctually paid, and may be made from time to time with
respect to the same or different items of Guaranteed Debt.  Such demand shall
be deemed made, given and received in accordance with Section 5.02 hereof.

         Section 1.06.  No Duty to Pursue Others.  It shall not be necessary for
the Agent or the Banks (and each of the Guarantors hereby waives any rights
which Guarantors may have to require the Agent or the Banks), in order to
enforce such payment by any of the Guarantors, first to (i) institute suit or
exhaust its rights against Borrower or other Persons now or hereafter liable on
the Guaranteed Debt, or any other Person, (ii) enforce the Agent's or the
Banks' rights against any security which shall ever have been given to secure
the Guaranteed Debt, (iii) enforce the Agent's or the Banks' rights against any
other guarantors of the Guaranteed Debt, (iv) join Borrower, or any other
Persons now or hereafter liable on the Guaranteed Debt in any action seeking to
enforce this Guaranty Agreement, (v) exhaust





                                      D-3
<PAGE>   104
any rights available to the Agent or to the Banks against any security or
guarantor which shall ever have been given to secure the Guaranteed Debt, or
(vi) resort to any other means of obtaining payment of the Guaranteed Debt.
Neither the Agent nor the Banks shall be required to mitigate damages or take
any other action to reduce, collect or enforce the Guaranteed Debt.

         Section 1.07.  Waiver of Notices, etc.  Each of the Guarantors agrees
to the provisions of the Notes, the Credit Agreement and the other Loan
Documents, and, except as specifically set forth in this Guaranty Agreement,
hereby waives notice of (i) any loans or advances, or the issuance of any
Letters of Credit, by the Agent or by the Banks to or at the request of
Borrower, (ii) acceptance of this Guaranty Agreement, (iii) any amendment,
modification, extension for any period, increase, refinancing or rearrangement
of the Notes or any supplement, modifications, amendment and/or restatement of
the Credit Agreement or of any of the other Loan Documents, (iv) the occurrence
of any breach by Borrower, or any Default or Event of Default, (v) the Agent's
or any of the Banks' transfer or disposition of the Guaranteed Debt, or any
part thereof, (vi) the sale or foreclosure (or posting or advertising for sale
or foreclosure) of any collateral for the Guaranteed Debt, (vii) protest, proof
of non-payment or default by Borrower, or (viii) any other action at any time
taken or omitted by the Agent or the Banks, and, generally, all demands and
notices of every kind in connection with this Guaranty Agreement, the Credit
Agreement and the other Loan Documents.

         Section 1.08.  Nature of Guaranty.  This Guaranty Agreement is an
irrevocable, absolute and continuing guaranty of payment and not a guaranty of
collection.  This Guaranty Agreement may not be revoked by any of the
Guarantors and shall continue to be effective with respect to any Guaranteed
Debt arising or created after any attempted revocation by any of the
Guarantors.  The fact that at any time or from time to time the Guaranteed Debt
may be increased, reduced or paid in full shall not release, discharge or
reduce the obligations of Guarantors with respect to the indebtedness or
obligations of Borrower, to the Agent or the Banks thereafter incurred (or
other Guaranteed Debt thereafter arising) under the Notes or otherwise.  This
Guaranty may be enforced by the Agent or the Banks and by any subsequent holder
or holders of the Guaranteed Debt and shall not be discharged by the assignment
or negotiation of all or part of the Guaranteed Debt.  Guarantors guarantee
that the Guaranteed Debt will be paid strictly in accordance with the terms of
the Notes, the Credit Agreement and the other Loan Documents, regardless of any
law of any tribunal affecting any such terms or the rights of the Agent or the
Banks with respect thereto.  The liability of the Guarantors under this
Guaranty Agreement shall be irrevocable, absolute and unconditional
irrespective of any change in the time, manner or place of payment of, or in
any other term of, all or any part of the Guaranteed Debt under the Notes, the
Credit Agreement or the other Loan Documents, or any other amendment, waiver of
or any consent to the departure from the Notes, the Credit Agreement or the
other Loan Documents.





                                      D-4
<PAGE>   105
         Section 1.09.  Payment of Expenses.  In the event that any of the
Guarantors breaches or fails to timely perform any provisions of this Guaranty
Agreement, each of the Guarantors agrees to pay to the Agent or to the Banks
all costs and expenses (including court costs and reasonable attorneys' fees)
incurred by the Agent or by the Banks in the enforcement hereof or the
preservation of the Banks' rights hereunder.  The covenant contained in this
Section 1.09 shall survive the payment of the Guaranteed Debt.

         Section 1.10.  Effect of Bankruptcy.  Pursuant to any Debtor Laws, or
any judgment, order or decision thereunder, in the event that, within four
years after the payment thereof, any of the Banks or the Agent must rescind or
restore any payment, or any part thereof, received by the any of the Banks or
the Agent in satisfaction of the Guaranteed Debt, as set forth herein, then any
prior release or discharge from the terms of this Guaranty Agreement given to
any of the Guarantors by any of the Banks or the Agent shall be without effect,
and this Guaranty Agreement shall remain in full force and effect.  Each of the
Guarantors' obligations hereunder shall not be discharged except by Guarantors'
performance of such obligations and then only to the extent of such
performance.  The covenant contained in this Section 1.10 shall survive the
payment of the Guaranteed Debt, and any portion thereof.


                                   ARTICLE II

              EVENTS AND CIRCUMSTANCES NOT REDUCING OR DISCHARGING
                          ANY GUARANTORS' OBLIGATIONS

         Each of the Guarantors hereby agrees that the liability of Guarantors
under this Guaranty Agreement is irrevocable, absolute and unconditional.  Each
of the Guarantors consents and agree to each of the following, and each of the
Guarantors further agrees that each of the Guarantors' obligations under this
Guaranty Agreement shall not be released, diminished, impaired, reduced or
adversely affected by any of the following, and waives any common law,
equitable or statutory, or other rights (including, without limitation, rights
to notice) which any such Guarantors might otherwise have as a result of or in
connection with any of the following:

         Section 2.01.  Modifications, etc.  Any renewal, extension for any
period, increase, amendment, modification, alteration, supplement or
rearrangement of all or any part of the Guaranteed Debt, the Notes, the Credit
Agreement or of any of the other Loan Documents or understandings or agreements
between Borrower, and the Agent or the Banks, or any other Persons, pertaining
to the Guaranteed Debt;

         Section 2.02.  Adjustment, etc.  Any adjustment, indulgence,
forbearance or compromise that might be granted or given by the Agent or the
Banks to Borrower, or any one or more of the Guarantors or any other guarantor
of the Guaranteed Debt;





                                      D-5
<PAGE>   106
         Section 2.03.  Condition of Borrower or Guarantors.  The insolvency,
bankruptcy, arrangement, adjustment, composition, liquidation, disability,
dissolution or lack of power of Borrower, or any other Person now or hereafter
liable for the payment of all or part of the Guaranteed Debt, including any of
the Guarantors; or any dissolution of Borrower, or any one or more of the
Guarantors or any other guarantor of the Guaranteed Debt, or any sale, lease or
transfer of any or all of the assets or properties of Borrower, or any one or
more of the Guarantors or any other guarantor of the Guaranteed Debt, or any
changes in the shareholders, partners, members or other composition of
Borrower, or any one or more of the Guarantors or any other guarantor of the
Guaranteed Debt; or any reorganization of Borrower, or any one or more of the
Guarantors or any other guarantor of the Guaranteed Debt;

         Section 2.04.  Invalidity of Guaranteed Debt.  The invalidity,
illegality or unenforceability of all or any part of the Guaranteed Debt, the
Notes, the Credit Agreement or any of the other Loan Documents, for any reason
whatsoever, including without limitation the fact that (i) the Guaranteed Debt,
or any part thereof, exceeds the amount permitted by Law, (ii) the act of
creating the Guaranteed Debt or any part thereof is ultra vires, (iii) the
officers, partners or representatives executing the Notes, the Credit Agreement
or the other Loan Documents acted in excess of their authority, (iv) the
Guaranteed Debt violates applicable usury Laws, (v) Borrower has valid
defenses, claims or offsets (whether at law, in equity or by agreement) which
render the Guaranteed Debt wholly or partially uncollectible from Borrower,
(vi) the creation, performance or repayment of the Guaranteed Debt (or the
execution, delivery and performance of any Loan Document) is illegal,
uncollectible or unenforceable, or (vii) the Notes, the Credit Agreement or any
of the other Loan Documents have been forged or otherwise are irregular or not
genuine or authentic;

         Section 2.05.  Release of Obligors.  Any full or partial release of the
liability of Borrower on the Guaranteed Debt or any part thereof, or any other
Person now or hereafter liable, whether directly or indirectly, jointly,
severally, or jointly and severally, to pay, perform, guarantee or assure the
payment of the Guaranteed Debt or any part thereof, it being recognized,
acknowledged and agreed by Guarantors that any Guarantors may be required to
pay the Guaranteed Debt in full without assistance or support of any other
Person, and none of the Guarantors has been induced to enter into this Guaranty
on the basis of a contemplation, belief, understanding or agreement that the
Agent or any of the Banks will look solely to other Persons to perform the
Guaranteed Debt;

         Section 2.06.  Other Security.  The taking or accepting of any other
security, collateral or guaranty, or other assurance of payment, for all or any
part of the Guaranteed Debt;

         Section 2.07.  Release of Collateral, etc.  Any release, surrender,
exchange, subordination, deterioration, waste, loss or impairment (including
without limitation negligent or unreasonable impairment) of any collateral,
property or security, at any time





                                      D-6
<PAGE>   107
existing in connection with, or assuring or securing payment of, all or any
part of the Guaranteed Debt;

         Section 2.08.  Care and Diligence.  The failure of the Agent or the
Banks or any other party to exercise diligence or reasonable care in the
preservation, protection, enforcement, sale or other handling or treatment of
all or any part of such collateral, property or security;

         Section 2.09.  Status of Liens.  The fact that any collateral, security
or Lien contemplated or intended to be given, created or granted as security
for the repayment of the Guaranteed Debt shall not be properly perfected or
created or continuously perfected or in existence, or shall prove to be
unenforceable or subordinate to any other Lien, it being recognized and agreed
by Guarantors that none of the Guarantors is entering into this Guaranty
Agreement in reliance on, or in contemplation of the benefits of, the validity,
enforceability, collectability or value of any collateral for the Guaranteed
Debt;

         Section 2.10.  Offset.  The Guaranteed Debt guaranteed hereby, and the
liabilities and obligations of each of the Guarantors to the Agent and the
Banks hereunder, shall not be reduced, discharged or released because of or by
reason of any existing or future right of offset, recoupment, claim or defense
of Borrower against the Agent or the Banks, or any other Person, or against
payment of the Guaranteed Debt, whether such right of offset, recoupment, claim
or defense arises in connection with the Guaranteed Debt (or the transactions
creating the Guaranteed Debt) or otherwise;

         Section 2.11.  Incorporation/Merger.  The reorganization, merger or
consolidation of Borrower, into or with any other corporation, partnership or
other entity or form;

         Section 2.12.  Preference.  Any payment by Borrower, to the Agent or
the Banks is held to constitute a preference under Debtor Laws, or for any
reason the Agent or any of the Banks is required to refund such payment or pay
such amount to Borrower, or any other Person; or

         Section 2.13.  Other Actions Taken or Omitted.  Any other action taken
or omitted to be taken with respect to the Guaranteed Debt, the Notes, the
Credit Agreement or any of the other Loan Documents, or the security and
collateral therefor, whether or not such action or omission prejudices
Guarantors or increases the likelihood that Guarantors will be required to pay
the Guaranteed Debt pursuant to the terms hereof including, without limitation,
any Advances made by the Agent or the Banks to Borrower, following any Default
or Event of Default; it is the unambiguous and unequivocal intention of each of
the Guarantors that each of the Guarantors shall be absolutely obligated to pay
the Guaranteed Debt when due, notwithstanding any occurrence, circumstance,
event, action, or omission whatsoever, whether contemplated or uncontemplated,
and whether or not otherwise or particularly described herein, except for the
full and final payment and satisfaction of the Guaranteed Debt.





                                      D-7
<PAGE>   108
                                  ARTICLE III

                   REPRESENTATIONS, WARRANTIES AND COVENANTS

         To induce Banks to enter into the Credit Agreement and the other Loan
Documents and to induce Banks to make the loans and otherwise extend credit to
Borrower, each of the Guarantors represents, warrants and covenants to each of
the Agents and the Banks that:

         Section 3.01.  Familiarity and Reliance.  Each of the Guarantors is
familiar with, and has independently reviewed books and records regarding, the
financial condition of Borrower; however, none of the Guarantors are relying on
such financial condition or any collateral as an inducement to enter into this
Guaranty Agreement.

         Section 3.02.  No Representation by Banks.  Neither the Agent nor the
Banks nor any other Person has made any representation, warranty or statement
to any of the Guarantors in order to induce each of the Guarantors to execute
this Guaranty Agreement except as heretofore provided in the recitals of this
Guaranty Agreement.

         Section 3.03.  Benefit.  Each of the Guarantors is a direct or indirect
subsidiary of the Borrower, and such entity derives benefit from its
relationship with the Borrower in connection with the ownership and operation
of the business of the Borrower and its Subsidiaries, and as a result thereof,
each of the Guarantors has received, or will receive, direct or indirect
benefit and reasonably equivalent value from the making of this Guaranty
Agreement.

         Section 3.04.  Determination of Benefit.  The Board of Directors of
each of the Guarantors has determined that this Guaranty Agreement directly or
indirectly benefits each of the Guarantors and is in the best interests of each
of the Guarantors.

         Section 3.05.  Legality.  The execution, delivery and performance by
each of the Guarantors of this Guaranty Agreement and the consummation of the
transactions contemplated hereunder do not, and will not, contravene or violate
any Law to which any of the Guarantors is subject or constitute a default (or
an event which with notice or lapse of time or both would constitute a default)
under, or result in the breach of, any Lien to which any of the Guarantors is a
party or which may be applicable to each of the Guarantors or any of their
respective assets.  This Guaranty Agreement is a legal and binding obligation
of each of the Guarantors and is enforceable in accordance with its terms,
except as limited by Debtor Laws.

         Section 3.06.  Use of Proceeds; Margin Stock.  None of the proceeds
from the Loans will be used, for the purpose of purchasing or carrying any
"margin stock" as defined in Regulations G, T, U or X, or for the purpose of
maintaining, reducing or retiring any Indebtedness which was originally
incurred to purchase or carry a "margin stock" or for any other purpose which
might constitute this transaction a "purpose credit" within the meaning





                                      D-8
<PAGE>   109
of Regulations G, T, U or X.  Guarantors have not taken and will not take any
action which might cause any of the Loan Documents to violate or be subject to
Regulations G, T, U or X, or any other regulations of the Board of Governors of
the Federal Reserve System or to violate Section 8 of the Securities Exchange
Act of 1934 or any rule or regulation thereunder, in each case as now or
hereafter may be in effect at the time such proceeds were used.

         Section 3.07.  Loan Documents.  To the extent that each of the
Guarantors is a party to any of the Loan Documents, each such Loan Document is
the legal and binding obligation of such Person, enforceable in accordance with
its terms.  None of the Guarantors have or has asserted, and none are aware of,
any claims, defenses, offset rights or similar rights or remedies with respect
to, or any defect in, the Loan Documents, which in any manner or effect would
diminish or impair any rights, Liens, privileges, benefits and remedies of the
Agent or the Banks as contemplated by the Loan Documents, or would preclude the
Agent or the Banks from enforcing and collecting the Obligations in the amount
and manner as provided in the Loan Documents.  None of the Guarantors has
revoked any of its obligations under any Loan Document to which it is a party,
and none has requested and/or received a release or termination of its
obligations thereunder.  The Agent and the Banks are authorized to rely upon
all representations, warranties, statements and other information, with respect
to the Borrower and its Affiliates, set forth in the Loan Documents, as true
and correct on the date hereof.  Each of the Guarantors hereby represents and
warrants that the representations and warranties pertaining to it as set forth
in the Credit Agreement are true and correct on the date hereof.

         Section 3.08.  Survival.  All representations and warranties made by
each of the Guarantors herein shall survive the execution hereof.


                                   ARTICLE IV

                     SUBORDINATION OF CERTAIN INDEBTEDNESS

         Section 4.01.  Subordination of All Guarantors Claims.  As used herein,
the term "Guarantors Claims" shall mean all debts and liabilities of Borrower,
to any of the Guarantors, whether such debts and liabilities now exist or are
hereafter incurred or arise, or whether the obligations of Borrower, thereon be
direct, contingent, primary, secondary, several, joint and several, or
otherwise, and irrespective of whether such debts or liabilities be evidenced
by notes, contract, open account, or otherwise, and irrespective of the person
or persons in whose favor such debts or liabilities may, at their inception,
have been, or may hereafter be created, or the manner in which they have been
or may hereafter be acquired by any of the Guarantors.  After the occurrence of
a Default, and so long thereafter as such Default continues, until the
Guaranteed Debt shall be paid and satisfied in full and the Guarantors shall
have performed all obligations hereunder, none of the Guarantors shall receive
or collect, directly or indirectly, from Borrower any amount upon the
Guarantors





                                      D-9
<PAGE>   110
Claims.  The Guarantors Claims shall not include all rights and claims of any
of the Guarantors against the Borrower (arising as a result of subrogation or
otherwise) as a result of any Guarantor's payment of all or a portion of the
Guaranteed Debt.  UNTIL ALL OF THE OBLIGATIONS HAVE BEEN PAID AND PERFORMED IN
FULL, EACH OF THE GUARANTORS EXPRESSLY AND SPECIFICALLY WAIVES ANY AND ALL
RIGHTS, WHETHER ARISING BY LAW OR AGREEMENT OR OTHERWISE, TO REIMBURSEMENT,
CONTRIBUTION, SUBROGATION, EXONERATION AND INDEMNIFICATION, AND TO PARTICIPATE
IN ANY CLAIM OR REMEDY OF ANY OF THE AGENT OR THE BANKS OR ANY OTHER PERSON
AGAINST BORROWER, OR ANY OTHER PERSON, WITH RESPECT TO THE GUARANTEED DEBT.
EACH OF THE GUARANTORS HAS CONSULTED WITH LEGAL COUNSEL OF ITS OWN CHOOSING AS
TO THE EFFECT OF THE FOREGOING WAIVERS.  If any Guarantor shall make payment to
Lender of all or any portion of the Obligations, and if all of the Obligations
shall be finally paid in full, Agent will, at such Guarantor's request and
expense, execute and deliver to such Guarantor (without recourse,
representation or warranty) appropriate documents necessary to evidence the
transfer by subrogation to such Guarantor of an interest in the Obligations
resulting from such payment by such Guarantor; provided that such transfer
shall be subject to Section 1.10 above.

         Section 4.02.  Claims in Bankruptcy.  In the event of receivership,
bankruptcy, reorganization, arrangement, debtor's relief, or other insolvency
proceedings involving Borrower as debtor, the Agent and the Banks shall have
the right to prove the claims of the Banks (and of the Agent, if any) in any
such proceeding so as to establish its rights hereunder and receive directly
from the receiver, trustee or other court custodian dividends, distributions
and payments which would otherwise be payable upon Guarantors Claims.  Each of
the Guarantors hereby assigns such dividends, distributions and payments to the
Agent for the benefit of the Banks.  Should the Agent or the Banks receive, for
application upon the Guaranteed Debt, any such dividend or payment which is
otherwise payable to any of the Guarantors, and which, as between Borrower and
Guarantors, shall constitute a credit upon the Guarantors Claims, then upon
payment to Banks in full of the Guaranteed Debt, each of the Guarantors shall
become subrogated to the rights of the Agent and the Banks to the extent that
such payments to the Agent and the Banks on the Guarantors Claims have
contributed toward the liquidation of the Guaranteed Debt, and such subrogation
shall be with respect to that proportion of the Guaranteed Debt which would
have been unpaid if Agent and the Banks had not received dividends or payments
upon the Guarantors Claims.

         Section 4.03.  Payments Held in Trust.  In the event that,
notwithstanding Sections 4.01 and 4.02 above, any of the Guarantors should
receive any funds, payment, claim or distribution which is prohibited by such
Sections, each of the Guarantors, unless otherwise directed in writing by the
Agent or the Banks, agree to immediately notify the Agent of receipt of same
and to hold in trust for the Banks an amount equal to the amount of all funds,
payments, claims or distributions so received, and agree that it shall have
absolutely no dominion over the amount of such funds, payments, claims or
distributions, except to





                                      D-10
<PAGE>   111
pay them promptly to the Agent for the benefit of the Banks, and Guarantors
covenant to immediately pay the same to the Agent for the benefit of the Banks.

         Section 4.04.  Liens Subordinate.  Each of the Guarantors agrees that
any Liens upon the assets and properties of Borrower, securing payment of the
Guarantors Claims shall be and remain inferior and subordinate to any Liens
upon the assets and properties of Borrower securing payment of the Guaranteed
Debt, regardless of whether such Liens in favor of any of the Guarantors or the
Agent for the benefit of the Banks presently exist or are hereafter created or
attach.  Without the prior written consent of the Agent, none of the Guarantors
shall (i) exercise or enforce any rights it may have against Borrower, or (ii)
foreclose, repossess, sequester or otherwise take steps or institute any action
or proceedings (judicial or otherwise, including without limitation the
commencement of, or joinder in, any liquidation, bankruptcy, rearrangement,
debtor's relief or insolvency proceeding) to enforce any Liens on assets of
Borrower, held by any of the Guarantors.


                                   ARTICLE V

                                 MISCELLANEOUS

         Section 5.01.  Waiver.  No failure to exercise, and no delay in
exercising, on the part of the Agent or the Banks, any right hereunder shall
operate as a waiver thereof, nor shall any single or partial exercise thereof
preclude any other or further exercise thereof or the exercise of any other
right.  The rights of the Agent and the Banks hereunder shall be in addition to
all other rights provided by law.  No modification or waiver of any provision
of this Guaranty Agreement, nor consent to departure therefrom, shall be
effective unless in writing and signed by Banks and no such consent or waiver
shall extend beyond the particular case and purpose involved.  No notice or
demand given in any case shall constitute a waiver of the right to take other
action in the same, similar or other instances without such notice or demand.

         Section 5.02.  Notices.  Except for telephonic notices permitted
herein, any notices or other communications required or permitted to be given
by this Agreement or any other Loan Documents and instruments referred to
herein must be (i) given in writing and personally delivered or mailed by
prepaid certified or registered mail, or (ii) made by telex or telecopy
delivered or transmitted, to the party to whom such notice of communication is
directed, to the address of such party as follows:  (a) if to Guarantors, c/o
Noble Drilling Corporation, 10370 Richmond Avenue, Suite 400, Houston, Texas
77042, Fax Number: (713) 974-3181, Attention:  Byron L. Welliver, Sr. Vice
President - Finance and Treasurer, with copy to Thompson & Knight, a
Professional Corporation, 1700 Pacific Avenue, Suite 3300, Dallas, Texas 75201,
Fax Number: (214) 969-1751, Attention: Robert D. Campbell, Esq.; and (b) if to
Agent, as set forth therefor in the Credit Agreement, and if to the Banks, then
in care of the Agent, all with copy to Fulbright & Jaworski L.L.P., 1301
McKinney, Suite 5100, Houston, Texas 77010, Fax Number: (713) 651-5246,
Attention: Joshua P. Agrons;





                                      D-11
<PAGE>   112
provided however, the failure of any of the Guarantors, Agent or the Banks to
provide a copy of any notice or other communication to the other party's
counsel as specified in the foregoing clause shall not affect the
effectiveness, legitimacy and significance of any notice or other communication
sent by any of the Guarantors to the Agent or the Banks, or the Agent of any of
the Guarantors, so long as such notice or other communication is otherwise in
compliance with this Section 5.02.  Any notice to be mailed or personally
delivered may be mailed or delivered to the principal offices of the party to
whom such notice is addressed.  Any such notice or other communication shall be
deemed to have been given (whether actually received or not) on the day it is
mailed or personally delivered as aforesaid or, if transmitted by telex, on the
day that such notice is transmitted as aforesaid; provided, however, that any
telephonic or other notice received by a party after 11:00 a.m. (Houston, Texas
time) on any day shall be deemed to have been given on the next succeeding day.
Any party may change its address for purposes of this Agreement by giving
notice of such change to the other party pursuant to this Article 5.02.

         Section 5.03.  Entirety and Amendments.  This Guaranty Agreement
embodies the entire agreement between the parties and supersedes all prior
agreements and understandings, if any, relating to the subject matter hereof
and this Guaranty Agreement may be amended only by an instrument in writing
executed by the parties hereto.

         Section 5.04.  Parties Bound; Assignment.  This Guaranty Agreement
shall be binding upon and inure to the benefit of the parties hereto and their
respective successors, assigns and legal representatives; provided, however,
none of the Guarantors may, without the prior written consent of the Agent,
assign any of its rights, duties or obligations hereunder.

         Section 5.05.  Multiple Parties.  Anyone signing this Guaranty
Agreement shall be bound thereby, whether or not any other party signs this
Guaranty Agreement or is released therefrom at any time.  It is specifically
agreed that the Agent may enforce the provisions hereof with respect to one or
more of the Guarantors without seeking to enforce the same as to all or any
other such parties, and each of the Guarantors hereby waives any requirement of
joinder of all or any other of the other parties hereto in any suit or
proceeding to enforce the provisions hereof.  The obligations created by this
Guaranty Agreement shall be joint and several (and not merely joint) with
respect to each of the Guarantors.

         Section 5.06.  Headings.  Section headings are for convenience of
reference only and shall in no way affect the interpretation of this Guaranty
Agreement.

         Section 5.07.  Rights and Remedies.  If any of the Guarantors becomes
liable for any indebtedness owing by any of the Borrower to the Agent or to the
Banks, by endorsement or otherwise, other than under this Guaranty Agreement,
such liability shall not be in any manner impaired or affected hereby and the
rights of the Agent and the Banks hereunder shall be cumulative of any and all
other rights of the Agent or the Banks hereunder that Banks may have against
any of the Guarantors.  The exercise by the Agent or the Banks of





                                      D-12
<PAGE>   113
any right under this Guaranty Agreement, the Credit Agreement, any of the other
Loan Documents, any other instrument, document or agreement, or at law or in
equity, shall not preclude the concurrent or subsequent exercise of any other
right.

         Section 5.08.  Multiple Counterparts.  This Guaranty Agreement may be
executed in any number of counterparts, all of which taken together shall
constitute one and the same agreement, and any of the parties hereto may
execute this Guaranty Agreement by signing any such counterpart.

         Section 5.09.  Choice of Law.  THIS GUARANTY SHALL BE CONSTRUED IN
ACCORDANCE WITH AND GOVERNED BY THE INTERNAL LAWS OF THE STATE OF TEXAS.

         Section 5.10.  Submission to Jurisdiction.  To the extent not expressly
prohibited by law from time to time in effect, each of the Guarantors hereby
irrevocably and unconditionally:  (i) submits for itself and its property in
any legal action or proceeding relating to this Guaranty Agreement or for
recognition and enforcement of any judgment in respect thereof, to the
non-exclusive general jurisdiction of the Courts of Harris County, Texas, the
Courts of the United States of America for the Southern District of Texas,
Houston Division and Appellate Courts from any thereof; (ii) consents that any
such action or proceeding may be brought in such courts, and waives any
objection that it may now or hereafter have to the venue of any such action or
proceeding in any such court or that any such action or proceeding was brought
in an inconvenient court and agrees not to plead or claim the same; (iii)
agrees that service of process in any such action or proceeding may be effected
by mailing a copy thereof by registered or certified mail (or any substantially
similar form of mail), postage prepaid, to Guarantor at its address set forth
in Section 5.02 of this Guaranty Agreement or at such other address of which
Agent shall have been notified pursuant thereto; and (iv) agrees that nothing
herein shall impair the right of Agent to effect service of process in any
other manner permitted by law or shall limit the right to sue in any other
jurisdiction.

         EXECUTED effective as of the day and year first above written.

                                  GUARANTORS:


                                  NOBLE DRILLING (U.S.), INC.


                                  By:_____________________________________
                                              Byron L. Welliver 
                                              Senior Vice President     





                                      D-13
<PAGE>   114
                                  NOBLE DRILLING (WEST AFRICA), INC.


                                  By:_____________________________________
                                               Byron L. Welliver 
                                               Senior Vice President      


                                  NOBLE DRILLING (MEXICO), INC.


                                  By:_____________________________________
                                               Alan Krenek
                                               Treasurer





                                      D-14
<PAGE>   115

                                   EXHIBIT E

               FORM OF INTERCOMPANY REVOLVING CREDIT DEMAND NOTE


$20,000,000.00                                                 ________, 199__


         For value received, ___________________________________________, a
___________________ corporation (the "Borrower"), promises to pay on demand, or
if no demand be sooner made then on or before June __, 1996, to the order of
Noble Drilling Corporation, a Delaware corporation ("Noble"), at its principal
executive offices located at 10370 Richmond Avenue, Suite 400, Houston, Texas
77042, the principal sum of TWENTY MILLION AND N0/100 DOLLARS ($20,000,000.00),
or such lesser amount as shall equal the aggregate unpaid principal amount of
the loans made by Noble hereunder on or after the date hereof to the Borrower,
in lawful money of the United States of America and in immediately available
funds.

         All payments shall be applied first to accrued unpaid interest and the
balance to principal.  Prepayments shall be permitted on this Note without
premium or penalty.

         All past due principal and interest on this Note shall bear interest
from maturity thereof until paid at a per annum rate equal to the Default Rate
provided in the Credit Agreement.  Accrued interest on past due principal and
interest shall be payable on demand.

         This Note is one of the Intercompany Revolving Credit Notes referred
to in the Credit Agreement dated as of June __, 1994, by and among Noble, First
Interstate Bank of Texas, National Association, as Agent (the "Agent"), and the
financial institutions party thereto (such Credit Agreement, together with all
amendments or supplements thereto, being the "Credit Agreement"), and, as such,
will be pledged to the Agent by Noble to secure the various obligations of
Noble under the Credit Agreement.  Capitalized terms used in this Note and not
defined in this Note, but which are defined in the Credit Agreement, have the
respective meanings herein as are assigned to them in the Credit Agreement.

         This Note is a revolving credit note evidencing intercompany loans
made from time to time on or after the date hereof by Noble to Borrower, and it
is contemplated that by reason of prepayments hereon there may be times when no
indebtedness is owing hereunder; but notwithstanding such occurrence, this Note
shall remain valid and shall be in full force and effect as to each principal
advance made hereunder subsequent to each such occurrence.

         It is the intent of Noble and the Borrower in the execution and
performance of this Note to remain in strict compliance with Applicable Law
from time to time in effect.  In furtherance thereof, Noble and the Borrower
stipulate and agree that none of the terms and provisions





                                      E-1
<PAGE>   116
contained in this Note shall ever be construed to create a contract to pay for
the use, forbearance or detention of money with interest at a rate or in an
amount in excess of the maximum rate or amount of interest permitted to be
charged under Applicable Law.  For purposes of this Note, "interest" shall
include the aggregate of all charges that constitutes interest under Applicable
Law that are contracted for, charged, reserved, received or paid under this
Note.  Borrower shall never be required to pay unearned interest and shall
never be required to pay interest at a rate or in an amount in excess of the
maximum rate or amount or interest that may be lawfully charged under
Applicable Law, and the provisions of this paragraph shall control over all
other provisions of this Note which may be in apparent conflict herewith.  If
this Note is prepaid, or if the maturity of this Note is accelerated for any
reason, or if under any other contingency the effective rate or amount of
interest which would otherwise be payable under this Note would exceed the
maximum rate or amount of interest Noble or the holder of this Note is allowed
by Applicable Law to charge, contract for, take, reserve or receive, or in the
event that Noble or any holder of this Note shall charge, contract for, take,
reserve or receive monies deemed to constitute interest which would, in the
absence of this provision, increase the effective rate or amount of interest
payable under this Note to a rate or amount in excess of that permitted to be
charged, contracted for, taken, reserved or received under Applicable Law then
in effect, then the principal amount of this Note or the amount of interest
which would otherwise be payable under this Note or both shall be reduced to
the amount allowed under Applicable Law as now or hereinafter construed by the
courts having jurisdiction, and all such monies so charged, contracted for,
taken, reserved or received as are deemed to constitute interest in excess of
the maximum rate or maximum amount of interest permitted by Applicable Law
shall immediately be returned to or credited to the account of the Borrower
upon such determination.  Noble and the Borrower further stipulate and agree
that without limitation of the foregoing, all calculations of the rate or the
amount of interest contracted for, charged, taken, reserved or received under
this Note which are made for the purpose of determining whether such rate or
amount exceeds the maximum lawful rate or amount, shall be made to the extent
permitted by Applicable Law, by amortizing, prorating, allocating and spreading
during the period of the full stated term of this Note, all interest at any
time contracted for, charged, taken, reserved or received from the Borrower or
otherwise by Noble or any holder of this Note.

         The Borrower and all sureties, endorsers and guarantors of this Note
waive demand, presentment for payment, notice of nonpayment, protest, notice of
protest, notice of intent to accelerate maturity, notice of acceleration of
maturity and all other notices, filing of suit and diligence in collecting this
Note or enforcing any of the security herefor, and agree to any substitution,
exchange or release of any such security or guaranty or the release of any
party primarily or secondarily liable hereon and further agree that it will not
be necessary for any holder hereof, in order to enforce payment of this Note by
such holder, to first institute suit or exhaust its remedies against any
security herefor or guarantor hereof, and consent to any one or more extensions
or postponements of time of payment of this Note on any terms or any other
indulgences with respect hereto, without notice thereof to any of them.  Each
such person agrees that his, her or its liability on or with respect to this
Note shall not be affected by any





                                      E-2
<PAGE>   117
release of or change in any guaranty or security at any time existing or by any
failure to perfect or maintain perfection of any lien against or security
interest in any such security or the partial or complete enforceability of any
guaranty or other surety obligation, in each case in whole or in part, with or
without notice and before or after maturity.

         To the extent not expressly prohibited by law from time to time in
effect, the Borrower hereby irrevocably and unconditionally:  (i) submits for
itself and its property in any legal action or proceeding relating to this Note
or for recognition and enforcement of any judgment in respect thereof, to the
non-exclusive general jurisdiction of the Courts of Harris County, Texas, the
Courts of the United States of America for the Southern District of Texas,
Houston Division and Appellate Courts from any thereof; (ii) consents that any
such action or proceeding may be brought in such courts, and waives any
objection that it may now or hereafter have to the venue of any such action or
proceeding in any such court or that any such action or proceeding was brought
in an inconvenient court and agrees not to plead or claim the same; (iii)
agrees that service of process in any such action or proceeding may be effected
by mailing a copy thereof by registered or certified mail (or any substantially
similar form of mail), postage prepaid, to Borrower at its address set forth in
the first paragraph of this Note or at such other address of which Noble shall
have been notified pursuant thereto; and (iv) agrees that nothing herein shall
impair the right of Noble to effect service of process in any other manner
permitted by law or shall limit the right to sue in any other jurisdiction.

         THIS NOTE SHALL BE CONSTRUED IN ACCORDANCE WITH AND BE GOVERNED BY THE
INTERNAL LAWS OF THE STATE OF TEXAS.

                                        BORROWER:


                                        _______________________________________


                                        By:_____________________________________
                                        Name:___________________________________
                                        Title:__________________________________





                                      E-3
<PAGE>   118


                           NOBLE DRILLING CORPORATION

                            Loan Formula Certificate


Agent:         First Interstate Bank of Texas, N.A.

Dated as of:   ______________________, 199_.

Borrower:      Noble Drilling Corporation

         This Loan Formula Certificate is delivered pursuant to that certain
Credit Agreement dated as of June __, 1994 (as renewed, extended, amended or
modified, the "Credit Agreement") among the Borrower, the Agent and the Banks
party thereto.  Unless otherwise defined herein, capitalized terms used and not
otherwise defined herein shall have the meanings set forth therefor in the
Credit Agreement.

<TABLE>
<S>      <C>                                                  <C>                         <C>
1.       Total Accounts Receivable per ------------  199--                                --------------------
         Aging Report         

2.       Total US and UK Accounts Receivable                                     
                                                                                          --------------------
         Less:   A)   Portion greater than 90 days
                      from invoice                            -------------------
                 B)   Amount exceeding 15% of Line 1
                      from same account                       -------------------
                 C)   Accounts with 25% concentration of
                      past dues                               -------------------
                 D)   Other ineligible accounts               -------------------

3.       Total Eligible US and UK Accounts                                                --------------------

4.       Total Other International Accounts (billed in
         US $)                                                -------------------
         Less    A)   Portion greater than 90 days from
                      invoice (Portion greater than 120 days
                      for Shell Nigeria)                      -------------------
                 B)   Amount exceeding 15% of Line 1
                      from same account                       -------------------
                 C)   Accounts with 25% concentration
                      past 90 days (Past 150 days for
                      Shell Nigeria)                          -------------------
                 D)   Other ineligible accounts               -------------------
</TABLE>
<PAGE>   119
<TABLE>
<S>     <C>                                                                               <C>
5.       Total Eligible Other International Accounts                                      --------------------

6.       Total Eligible Accounts (Line 3 + Line 5)                                        --------------------

7.       75% of Line 6                                                                    --------------------

8.       Revolving Loan Commitment
         (Lesser of Line 7 and $25,000,000)                                               --------------------

9.       Aggregate Principal Balance of Revolving Notes                                   --------------------

10.      AVAILABILITY UNDER REVOLVING LOAN
         (LINE 8 - LINE 9)                                                                --------------------

11.      ADDITIONAL AMOUNT REQUESTED UNDER REVOLVER                                       --------------------


12.      Letter of Credit Commitment
         (Lesser of (x) $5,000,000 and
         (y) Line 7 - Line 9 - Line 11)                                                   --------------------

13.      Aggregate Letters of Credit Issued                                               --------------------

14.      AVAILABILITY UNDER LETTER OF CREDIT FACILITY                                     --------------------

15.      ADDITIONAL AMOUNT REQUESTED TO ISSUE UNDER
         LETTER OF CREDIT                                                                 --------------------
</TABLE>

16.      The undersigned, an Authorized Representative of Borrower, hereby
         certifies that:

                 (i)    He is familiar with and knowledgeable of all the terms,
         agreements, provisions, warranties, representations and covenants of
         the Credit Agreement and the other Loan Documents;

                 (ii)   His name appears on the specimen of signatures and
         incumbency certificate delivered to the Agent by the Borrower and now
         in effect, and he is authorized to execute this Certificate on behalf
         of the Borrower;

                 (iii)  All of the figures and information set forth herein and
         in any schedules attached hereto are, to the best of his knowledge,
         true and correct as of the date of this Certificate and have been
         prepared, presented, computed and calculated in accordance with the
         respective provisions of the Credit Agreement;





                                      -2-
<PAGE>   120
                 (iv)   As of and on the date of this Certificate, to the best
         of his knowledge, no condition, event or act which constitutes a
         Default or an Event of Default under the Credit Agreement exists, or
         will exist upon the making of any Revolving Loan requested above,
         except as follows:

         ______________________________________________________________________

         ______________________________________________________________________;

                 (v)    The representations and warranties of the Borrower made
         or referred to in the Credit Agreement and the other Loan Documents
         (other than those representations and warranties that are by their
         express terms limited to the date of the instrument in which they are
         initially made or in respect to which each such change shall be and
         has been communicated, in writing, to the Agent and approved, in
         writing, by the Agent) are, to the best of his knowledge, true and
         correct in all material respects as of and on the date of this
         Certificate, except as follows:

         ______________________________________________________________________
                                                                             
         __________________________________________________________; and

                 (vi)   There has been, to the best of his knowledge, no
         Material Adverse Effect has occurred with respect to Borrower on a
         Consolidated basis, since the date of the financial statements
         (audited or unaudited, as the case may be) of the Borrower most
         recently prepared and delivered to Agent, except as follows:

         ______________________

         ______________________________________________________________________.


                                        NOBLE DRILLING CORPORATION


                                        By:_____________________________________
                                        Name:___________________________________
                                        Title:__________________________________





                                      -3-
<PAGE>   121


                           NOBLE DRILLING CORPORATION

                               Loan Request Form


Agent:        First Interstate Bank of Texas, N.A.

Dated as of:  ___________________, 199__.

Borrower:     Noble Drilling Corporation

         This Loan Request Form is delivered pursuant to that certain Credit
Agreement dated as of June _, 1994 (as renewed, extended, amended or modified,
the "Credit Agreement") among the Borrower, the Agent and the other banks party
thereto.  Unless otherwise defined herein, capitalized terms used and not
otherwise defined herein shall have the meanings set forth therefor in the
Credit Agreement.  This Loan Request Form is used to request a Loan, the
issuance of a Letter of Credit or the conversion of a Loan to another Type.

         1.      Borrower hereby requests the following Loan or financial
accommodation:

<TABLE>
<CAPTION>
 A.  Type of Loan                   Amount                   Interest Period                  Rate
     ------------                   ------                   ---------------                  ----
 <S>                          <C>                         <C>                           <C>
 ___________________          ___________________         ______________________        ________________
 
 ___________________          ___________________         ______________________        ________________

 ___________________          ___________________         ______________________        ________________
</TABLE>

<TABLE>
<CAPTION>
B.    Letter of Credit                             Beneficiary                          Expiry Date
      ----------------                             -----------                          -----------
          Amount                                                                 
          ------
<S>                                        <C>                                  <C>
______________________________             _____________________________        ______________________________
</TABLE>


         2.      Borrower hereby requests the following conversions of Loans:

<TABLE>
<CAPTION>
  Present Loan                                        Amount of                Requested
  ------------                                        ---------                ---------
     Type                   Date of Loan                Loan                   Loan Type              Interest Paid
     ----                   ------------                ----                   ---------              -------------        
<S>                   <C>                         <C>                      <C>                     <C>          
_________________        __________________       _________________        _________________       __________________
                         
_________________        __________________       _________________        _________________       __________________

_________________        __________________       _________________        _________________       __________________
</TABLE>
<PAGE>   122
         3.      The Borrowing Date for the Loan(s), if any, contemplated in
paragraph 1(A) hereof is ____________, 19__ (which must comply with Section
2.03 of the Credit Agreement).

         4.      The Borrower hereby requests that the Loan requested in
numbered paragraph 1(A) hereof be disbursed into the accounts of Borrower at
the Agent, as follows:

<TABLE>
<CAPTION>
            Account No.                                               Amount
            -----------                                               ------
<S>                                                      <C>
____________________________________                     $__________________________.__
               --
____________________________________                      __________________________.__
               --
____________________________________                      __________________________.__
               --
              Total*                                     $                          .  
                                                          =============================            
</TABLE>                                                                       


*Must equal total Advance Requested.

         5.      The requested Loan, or the requested face amount of the Letter
of Credit, when added to the sum of (A) the aggregate unpaid principal amount
of outstanding Revolving Loans, and (B) the Total Letter of Credit Liabilities,
does not exceed the lesser of (Y) the Total Credit Commitment and (Z) the
Borrowing Base.

         6.      On the date hereof, the representations and warranties made by
Borrower in the Loan Documents are true and correct in all material respects,
except for such representations and warranties as are by their express terms
limited to a specific date.  No Default or Event of Default has occurred and is
continuing on the date hereof.

         7.      The terms and provisions of the Loan Formula Certificate to
which this Loan Request Form is attached, and which is executed by the same
Authorized Representative as executed this Loan Request Form, are incorporated
by reference herein.

                                        NOBLE DRILLING CORPORATION


                                        By:_____________________________________
                                        Print Name:_____________________________
                                        Print Title:____________________________





                                      -2-
<PAGE>   123

                        Quarterly Compliance Certificate
               For the Fiscal Quarter Ended _____________________

                           NOBLE DRILLING CORPORATION


         Reference is hereby made to that certain Credit Agreement dated as of
June ___, 1994 (as renewed, extended, amended or modified, the "Credit
Agreement"), among Noble Drilling Corporation (the "Borrower"), First
Interstate Bank of Texas, N.A. in its individual capacity and as agent (the
"Agent") for the other banks party thereto.  Each capitalized term used but not
otherwise expressly defined herein shall have the meaning set forth therefor in
the Credit Agreement.  This Quarterly Compliance Certificate is issued pursuant
to Section ______ of the Credit Agreement, for the purposes therein stated.

I.   CALCULATION OF SPECIAL PURPOSE FIXED CHARGE COVERAGE RATIO AS OF
     __________, 199_, ON A CONSOLIDATED AND ROLLING FOUR QUARTERS BASIS
     SECTION 5.05 (A)

     A.     (1)   Net Income                             ___________
            (2)   Plus:     Depreciation, Amortization,
                            Noncash Expense              ___________
                            Interest Expense             ___________
            (3)   Less:     Noncash Income               ___________
            (4)   EBITDA                                            ___________

     B.     (1)   Interest Expense                       ___________

            (2)   Plus:     Scheduled Maturities         ___________
                            Preferred Dividends          ___________
                            Capital Expenditures
                             less cash
                             balances in
                             excess of $25m              ___________

            (3)   Fixed Charges                                     ___________
 
            (4)   ACTUAL SPECIAL PURPOSE FIXED
                   CHARGE COVERAGE RATIO                            ___________
 
            (5)   Minimum Required Ratio                                   1.10
 
     C.     (1)   Applicable Margin:

<TABLE>
<CAPTION>
 Special Purpose Fixed                              For a Eurodollar                     For a Base
 Charge Coverage Ratio                                   Advance                        Rate Advance
 ---------------------                                   -------                        ------------
 <S>                                               <C>                                  <C>
 (a) At least 1.51                                 1.50% per annum                      0% per annum
</TABLE>
<PAGE>   124
<TABLE>
 <S>                                               <C>                                 <C>
 (b) At least 1.26 but less than 1.51              1.75% per annum                      0% per annum

 (c) Less than 1.26                                2.00% per annum                     .25% per annum
</TABLE>

     Note:  Applicable Margin fixed at 1.50% for Eurodollar Advances and zero
     for Base Rate Advances, through 12/31/94.

            (2)   APPLICABLE MARGIN
                  ________________________________________________

II.  CALCULATION OF FINANCIAL COVENANTS AS OF _____________, 199__

     A.     SECTION 5.05 (B) FIXED CHARGE COVERAGE RATIO

            Rolling Four Quarters Basis:

            (1)   Net Income                            ___________
            (2)   Plus:     Depreciation, Amortization,
                            Noncash Expense             ___________
                            Interest Expense            ___________
            (3)   Less:     Noncash Income              ___________
            (4)   EBITDA                                           ___________
 
            (5)   Interest Expense                      ___________
            (6)   Plus:     Scheduled Maturities        ___________
                            Preferred Dividends         ___________
            (7)   Fixed Charges                                    ___________
 
            (8)   Actual Fixed Charge Coverage Ratio               ___________
            (9)   Minimum Required Ratio                                  1.75

     B.     SECTION 5.06 TANGIBLE NET WORTH

            (1)   Consolidated Total Assets             ___________
            (2)   Less:     Intangibles                 ___________
            (3)   Less:     Total Liabilities
                              and Accruals              ___________
            (4)   Actual Consolidated Tangible
                   Net Worth                                       ___________

            Minimum Base Required:
            (1)   Base as of 4/30/94 (last calculation) $280,000,000 
                               
            (2)   Plus:     50% of Consolidated
                              Net Income                ___________
            (3)   Plus:     100% of Net Cash Proceeds





                                       2
<PAGE>   125
                             from Equity Offerings      ___________
            (4)   Plus:     85% of Net Non-Cash
                              Proceeds from
                              Equity Offerings          ___________
            (5)   Minimum Required Tangible
                   Net Worth                                       ___________

     C.     SECTION 5.07 LEVERAGE

            (1)   Consolidated Funded Debt              ___________
            (2)   Capital                               ___________

            (3)   Actual Debt to Capital Ratio                     ___________

            (4)   Maximum Allowed:                                        0.35

III.        The undersigned, an Authorized Representative of Borrower, hereby
            certifies that:

            (i)   He is familiar with and knowledgeable of all the terms,
     agreements, provisions, warranties, representations and covenants of the
     Credit Agreement and the other Loan Documents;

            (ii)  His name appears on the specimen of signatures and incumbency
     certificate delivered to the Agent by the Borrower and now in effect, and
     he is authorized to execute this Certificate on behalf of the Borrower;

            (iii) All of the figures and information set forth herein and in
     any schedules attached hereto are, to the best of his knowledge, true and
     correct as of the date of this Certificate and have been prepared,
     presented, computed and calculated in accordance with the respective
     provisions of the Credit Agreement;

            (iv)  As of and on the date of this Certificate, to the best of his
     knowledge, no condition, event or act which constitutes a Default or an
     Event of Default under the Credit Agreement exists, or will exist upon the
     making of any Revolving Loan requested above, except as follows:
     _________________________

     ________________________________________________________________________;

            (v)   The representations and warranties of the Borrower made or
     referred to in the Credit Agreement and the other Loan Documents (other
     than those representations and warranties that are by their express terms
     limited to the date of the instrument in which they are initially made or
     in respect to which each such change shall be and has been communicated,
     in writing, to the bank and approved, in writing, by the Agent) are, to
     the best of his knowledge, true and correct in all material respects as of
     and on the date of this Certificate, except as follows:
     _________________________

     ___________________________________________________________________; and





                                       3
<PAGE>   126
            (vi)  There has been, to the best of his knowledge, no material
     adverse change in the condition, financial or otherwise, of the Borrower
     on a consolidated basis, since the date of the financial statements
     (audited or unaudited, as the case may be) of the Borrower most recently
     prepared and delivered to Agent, except as follows:

     ___________________________________________________________________.

     Dated as of this ____ day of ____________, 199__.


                                           NOBLE DRILLING CORPORATION


                                        By:_____________________________________
                                        Name:___________________________________
                                        Title:__________________________________




                                       4

<PAGE>   1
                                                                   EXHIBIT 10.2


                            REVOLVING CREDIT NOTE


$12,500,000.00                                                    June 16, 1994


         NOBLE DRILLING CORPORATION, a Delaware corporation (the "Borrower"),
for value received, promises to pay to the order of CREDIT LYONNAIS CAYMAN
ISLAND BRANCH (the "Bank"), at the offices of FIRST INTERSTATE BANK OF TEXAS,
N. A. (the "Agent"), at 1000 Louisiana, 3rd Floor, Houston, Texas 77002, the
principal sum of TWELVE MILLION FIVE HUNDRED THOUSAND AND NO/100 DOLLARS
($12,500,000.00), or such lesser amount as shall equal the aggregate
unpaid principal amount of the Revolving Loans made by Bank hereunder to the
Borrower under the Credit Agreement, as hereafter defined, in lawful money of
the United States of America and in immediately available funds, on the dates
and in the principal amounts provided in the Credit Agreement referred to
below, and to pay interest on the unpaid principal amount as provided in the
Credit Agreement for such Revolving Loans made by the Bank to the Borrower
under the Credit Agreement, at such office, in like money and funds, for the
period commencing on the date of each such Revolving Loan until such Revolving
Loan shall be paid in full, at the rates per annum and on the dates provided in
the Credit Agreement.

         In addition to and cumulative of any payments required to be made
against this Note pursuant to the Credit Agreement, this Note, including all
principal and accrued interest then unpaid shall be due and payable on June 15,
1996, its final maturity.  All payments shall be applied first to accrued
unpaid interest and the balance to principal, except as otherwise expressly
provided in the Credit Agreement.  Prepayments on this Note shall be applied in
the manner set forth in the Credit Agreement.

         This Note is one of the Notes referred to in the Credit Agreement
dated as of the 16th day of June, 1994, by and among the Borrower and First
Interstate Bank of Texas, N. A., individually, and as Agent, and the financial
institutions party thereto (including the Bank) (such Credit Agreement,
together with all amendments or supplements thereto, being the "Credit
Agreement").  This Note evidences the Revolving Loans made by the Bank
thereunder and shall be governed by the Credit Agreement.  Capitalized terms
used in this Note and not defined in this Note, but which are defined in the
Credit Agreement, have the respective meanings herein as are assigned to them
in the Credit Agreement.

         This Note is a revolving credit note and it is contemplated that by
reason of prepayments hereon there may be times when no indebtedness is owing
hereunder; but notwithstanding such occurrence, this Note shall remain valid
and shall be full force and effect as to each principal advance made hereunder
subsequent to each occurrence.




                                                               BW
                                                 _______________________________
                                                   Initials for Identification
                                      
<PAGE>   2
         The Bank is hereby authorized by the Borrower to endorse on Schedule A
(or a continuation thereof) attached to this Note, the Type of each Revolving
Loan, the amount and date of each payment or prepayment of principal of each
such Revolving Loan received by the Bank and the Interest Periods and interest
rates applicable to each Revolving Loan, provided that any failure by the Bank
to make any such endorsement shall not affect the obligations of the Borrower
under the Credit Agreement or under this Note in respect of such Revolving
Credit Loans.

         It is the intent of the Bank and the Borrower in the execution and
performance of this Note to remain in strict compliance with Applicable Law
from time to time in effect.  In furtherance thereof, the Bank and the Borrower
stipulate and agree that none of the terms and provisions contained in this
Note, or in the Credit Agreement or any document securing or otherwise relating
to this Note, shall ever be construed to create a contract to pay for the use,
forbearance or detention of money with interest at a rate or in an amount in
excess of the maximum rate or amount of interest permitted to be charged under
Applicable Law.  For purposes of this Note "interest" shall include the
aggregate of all charges which constitutes interest under Applicable Law that
are contracted for, charged, reserved, received or paid under this Note.  The
Borrower shall never be required to pay unearned interest and shall never be
required to pay interest at a rate or in an amount in excess of the maximum
rate or amount or interest that may be lawfully charged under Applicable Law,
and the provisions of this paragraph shall control over all other provisions of
this Note, the Credit Agreement and any other instrument pertaining to or
securing this Note, which may be in apparent conflict herewith.  If this Note
is prepaid, or if the maturity of this Note is accelerated for any reason, or
if under any other contingency the effective rate or amount of interest which
would otherwise be payable under this Note would exceed the maximum rate or
amount of interest the Bank or the holder of this Note is allowed by Applicable
Law to charge, contract for, take, reserve or receive, or in the event that the
Bank or any holder of this Note shall charge, contract for, take, reserve or
receive monies deemed to constitute interest which would, in the absence of
this provision, increase the effective rate or amount of interest payable under
this Note to a rate or amount in excess of that permitted to be charged,
contracted for, taken, reserved or received under Applicable Law then in
effect, then the principal amount of this Note or the amount of interest which
would otherwise be payable under this Note or both shall be reduced to the
amount allowed under Applicable Law as now or hereinafter construed by the
courts having jurisdiction, and all such monies so charged, contracted for,
taken, reserved or received are deemed to constitute interest in excess of the
maximum rate or maximum amount of interest permitted by Applicable Law shall
immediately be returned to or credited to the account of the Borrower upon such
determination.  The Bank and the Borrower further stipulate and agree that
without limitation of the foregoing, all calculations of the rate or the amount
of interest contracted for, charged, taken, reserved or received under this
Note which are made for the purpose of determining whether such rate or amount
exceeds the maximum lawful rate or amount, shall be made to the extent
permitted by Applicable Law, by amortizing, prorating, allocating and spreading
during the period of the full stated term of this Note, all



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                                                 _______________________________
                                                   Initials for Identification
                                       -2-
<PAGE>   3
interest at any time contracted for, charged, taken, reserved or received from
the Borrower or otherwise by the Bank or the holders of this Note.

         The Borrower and all sureties, endorsers and guarantors of this Note
waive demand, presentment for payment, notice of nonpayment, protest, notice of
protest, notice of intent to accelerate maturity, notice of acceleration of
maturity and all other notices, filing of suit and diligence in collecting this
Note or enforcing any of the security herefor, and agree to any substitution,
exchange or release of any such security or guaranty, release of any party
primarily or secondarily liable hereon and further agree that it will not be
necessary for any holder hereof, in order to enforce payment of this Note by
such holder, to first institute suit or exhaust its remedies against any
security herefor or guarantor hereof, and consent to any one or more extensions
or postponements of time of payment of this Note on any terms or any other
indulgences with respect hereto, without notice thereof to any of them.  Each
such person agrees that his, her or its liability on or with respect to this
Note shall not be affected by any release of or change in any guaranty or
security at any time existing or by any failure to perfect or maintain
perfection of any lien against or security interest in any such security or the
partial or complete enforceability of any guaranty or other surety obligation,
in each case in whole or in part, with or without notice and before or after
maturity.

         The Credit Agreement, as at any time amended, provides for the
acceleration of the maturity of this Note upon the occurrence of certain events
and for prepayment of Revolving Loans upon the terms and conditions specified
therein.  Reference is hereby made to the Credit Agreement for all other
pertinent purposes.

         This Note is issued pursuant to and is entitled to the benefits of the
Credit Agreement.

         THIS NOTE SHALL BE CONSTRUED IN ACCORDANCE WITH AND BE GOVERNED BY THE
INTERNAL LAWS OF THE STATE OF TEXAS AND THE UNITED STATES OF AMERICA FROM TIME
TO TIME IN EFFECT.

                                        NOBLE DRILLING CORPORATION


                                                /s/  BYRON L. WELLIVER
                                        By:_____________________________________
                                        Byron L. Welliver, Senior Vice
                                        President - Finance and Treasurer





                                        

                                     -3-

<PAGE>   1
                                                                 EXHIBIT 10.3

                               REVOLVING CREDIT NOTE


$12,500,000.00                                                  June 16, 1994


        NOBLE DRILLING CORPORATION, a Delaware corporation (the "Borrower"),
for value received, promises to pay to the order of FIRST INTERSTATE BANK OF
TEXAS, N.A.  (the "Bank"), at the offices of FIRST INTERSTATE BANK OF TEXAS, 
N.A. (the "Agent"), at 1000 Louisiana, 3rd Floor, Houston, Texas 77002, the
principal sum of TWELVE MILLION FIVE HUNDRED THOUSAND AND NO/100 DOLLARS 
DOLLARS ($12,500,000.00), or such lesser amount as shall equal the aggregate
unpaid principal amount of the Revolving Loans made by Bank hereunder to the
Borrower under the Credit Agreement, as hereafter defined, in lawful money of
the United States of America and in immediately available funds, on the dates
and in the principal amounts provided in the Credit Agreement referred to
below, and to pay interest on the unpaid principal amount as provided in the
Credit Agreement for such Revolving Loans made by the Bank to the Borrower
under the Credit Agreement, at such office, in like money and funds, for the
period commencing on the date of each such Revolving Loan until such Revolving
Loan shall be paid in full, at the rates per annum and on the dates provided in
the Credit Agreement.

         In addition to and cumulative of any payments required to be made
against this Note pursuant to the Credit Agreement, this Note, including all
principal and accrued interest then unpaid shall be due and payable on June 15,
1996, its final maturity.  All payments shall be applied first to accrued
unpaid interest and the balance to principal, except as otherwise expressly
provided in the Credit Agreement.  Prepayments on this Note shall be applied in
the manner set forth in the Credit Agreement.

         This Note is one of the Notes referred to in the Credit Agreement
dated as of the 16th day of June, 1994, by and among the Borrower and First
Interstate Bank of Texas, N. A., individually, and as Agent, and the financial
institutions party thereto (including the Bank) (such Credit Agreement,
together with all amendments or supplements thereto, being the "Credit
Agreement").  This Note evidences the Revolving Loans made by the Bank
thereunder and shall be governed by the Credit Agreement.  Capitalized terms
used in this Note and not defined in this Note, but which are defined in the
Credit Agreement, have the respective meanings herein as are assigned to them
in the Credit Agreement.

        This Note is a revolving credit note and it is contemplated that by
reason of prepayments hereon there may be times when no indebtedness is owing
hereunder; but notwithstanding such occurrence, this Note shall remain valid
and shall be in full force and effect as to each principal advance made
hereunder subsequent to each such occurrence.





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                                              _______________________________
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<PAGE>   2
         The Bank is hereby authorized by the Borrower to endorse on Schedule A
(or a continuation thereof) attached to this Note, the Type of each Revolving
Loan, the amount and date of each payment or prepayment of principal of each
such Revolving Loan received by the Bank and the Interest Periods and interest
rates applicable to each Revolving Loan, provided that any failure by the Bank
to make any such endorsement shall not affect the obligations of the Borrower
under the Credit Agreement or under this Note in respect of such Revolving
Credit Loans.

        It is the intent of the Bank and the Borrower in the execution and
performance of this Note to remain in strict compliance with Applicable Law
from time to time in effect.  In furtherance thereof, the Bank and the Borrower
stipulate and agree that none of the terms and provisions contained in this
Note, or in the Credit Agreement or any document securing or otherwise relating
to this Note, shall ever be construed to create a contract to pay for the use,
forbearance or detention of money with interest at a rate or in an amount in
excess of the maximum rate or amount of interest permitted to be charged under
Applicable Law.  For purposes of this Note "interest" shall include the
aggregate of all charges which constitutes interest under Applicable Law that
are contracted for, charged, reserved, received or paid under this Note.  The
Borrower shall never be required to pay unearned interest and shall never be
required to pay interest at a rate or in an amount in excess of the maximum
rate or amount or interest that may be lawfully charged under Applicable Law,
and the provisions of this paragraph shall control over all other provisions of
this Note, the Credit Agreement and any other instrument pertaining to or
securing this Note, which may be in apparent conflict herewith.  If this Note
is prepaid, or if the maturity of this Note is accelerated for any reason, or
if under any other contingency the effective rate or amount of interest which
would otherwise be payable under this Note would exceed the maximum rate or
amount of interest the Bank or the holder of this Note is allowed by Applicable
Law to charge, contract for, take, reserve or receive, or in the event that the
Bank or any holder of this Note shall charge, contract for, take, reserve or
receive monies deemed to constitute interest which would, in the absence of
this provision, increase the effective rate or amount of interest payable under
this Note to a rate or amount in excess of that permitted to be charged,
contracted for, taken, reserved or received under Applicable Law then in
effect, then the principal amount of this Note or the amount of interest which
would otherwise be payable under this Note or both shall be reduced to the
amount allowed under Applicable Law as now or hereinafter construed by the
courts having jurisdiction, and all such monies so charged, contracted for,
taken, reserved or received are deemed to constitute interest in excess of the
maximum rate or maximum amount of interest permitted by Applicable Law shall
immediately be returned to or credited to the account of the Borrower upon such
determination.  The Bank and the Borrower further stipulate and agree that
without limitation of the foregoing, all calculations of the rate or the amount
of interest contracted for, charged, taken, reserved or received under this
Note which are made for the purpose of determining whether such rate or amount
exceeds the maximum lawful rate or amount, shall be made to the extent
permitted by Applicable Law, by amortizing, prorating, allocating and spreading
during the period of the full stated term of this Note, all




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                                                 _______________________________
                                                     Initials for Identification
                                      -2-
<PAGE>   3
interest at any time contracted for, charged, taken, reserved or
received from the Borrower or otherwise by the Bank or the holders of this
Note.

         The Borrower and all sureties, endorsers and guarantors of this Note
waive demand, presentment for payment, notice of nonpayment, protest, notice of
protest, notice of intent to accelerate maturity, notice of acceleration of
maturity and all other notices, filing of suit and diligence in collecting this
Note or enforcing any of the security herefor, and agree to any substitution,
exchange or release of any such security or guaranty, release of any party
primarily or secondarily liable hereon and further agree that it will not be
necessary for any holder hereof, in order to enforce payment of this Note by
such holder, to first institute suit or exhaust its remedies against any
security herefor or guarantor hereof, and consent to any one or more extensions
or postponements of time of payment of this Note on any terms or any other
indulgences with respect hereto, without notice thereof to any of them.  Each
such person agrees that his, her or its liability on or with respect to this
Note shall not be affected by any release of or change in any guaranty or
security at any time existing or by any failure to perfect or maintain
perfection of any lien against or security interest in any such security or the
partial or complete enforceability of any guaranty or other surety obligation,
in each case in whole or in part, with or without notice and before or after
maturity.

         The Credit Agreement, as at any time amended, provides for the
acceleration of the maturity of this Note upon the occurrence of certain events
and for prepayment of Revolving Loans upon the terms and conditions specified
therein.  Reference is hereby made to the Credit Agreement for all other
pertinent purposes.

         This Note is issued pursuant to and is entitled to the benefits of the
Credit Agreement.

         THIS NOTE SHALL BE CONSTRUED IN ACCORDANCE WITH AND BE GOVERNED BY THE
INTERNAL LAWS OF THE STATE OF TEXAS AND THE UNITED STATES OF AMERICA FROM TIME
TO TIME IN EFFECT.

                                        NOBLE DRILLING CORPORATION



                                        By:  /s/ BYRON L. WELLIVER      
                                            _______________________________
                                      
                                            Byron L. Welliver, Senior Vice
                                           President - Finance and Treasurer




                                     -3-

<PAGE>   1

                                                                 EXHIBIT 10.4


                               GUARANTY AGREEMENT

         THIS GUARANTY AGREEMENT ("Guaranty") is executed by each of the
corporations signatory hereto (collectively, the "Guarantors", and each
individually a "Guarantor"), in favor of First Interstate Bank of Texas, N.A.,
a national banking association in its individual capacity and as agent for the
Banks party to that certain Credit Agreement dated as of June 16, 1994 between
Noble Drilling Corporation, a Delaware corporation ("Borrower") and such Banks.

         WHEREAS, each Guarantor hereby acknowledges and agrees that the
financial accommodations to be made to Borrower pursuant to the Credit
Agreement (as hereinafter defined) will materially benefit Borrower and each
Guarantor, and in recognition of this fact, each Guarantor desires to secure
the payment of any and all indebtedness, obligations and liabilities to Agent
or to Banks now, heretofore or hereafter arising under, or in connection with
the Guaranteed Indebtedness (as hereinafter defined);

         WHEREAS, the Banks are not willing to make the loans under the Credit
Agreement or otherwise extend credit to Borrower unless the Guarantors
unconditionally and irrevocably guarantee payment of all present and future
indebtedness and obligations of the Borrower to the Banks,

         NOW, THEREFORE, in consideration of credit and financial
accommodations extended or to be extended to the Borrower, by and for other
good, fair and valuable considerations and reasonably equivalent value, the
receipt and sufficiency of which are hereby acknowledged, the Guarantors hereby
agree as follows:


                                   ARTICLE I

                          NATURE AND SCOPE OF GUARANTY

         Section 1.01.  Guaranty of Obligation.  Guarantors hereby irrevocably,
jointly and severally, and unconditionally guarantee to the Agent and to each
of the Banks and their respective successors and assigns, when due (and
howsoever such due date or maturity shall arise), (i) the due and punctual
payment of the Guaranteed Debt as that term is hereinafter defined; and (ii)
the performance of all other obligations, liabilities, covenants and agreements
under the Credit Agreement.  Guarantors hereby irrevocably and unconditionally
covenant and agree that each is jointly and severally liable for the Guaranteed
Debt as primary obligor.





                              
<PAGE>   2
         Section 1.02.  Definitions.

         (a)     As used herein, the following capitalized terms shall have the
following meanings:

         "Agent" means First Interstate Bank of Texas, N.A., as agent for the
Banks party to the Credit Agreement, or such Person as is successor thereto as
"agent" for the Banks.

         "Banks" means each of the banks party to the Credit Agreement and such
banks' respective successors and assigns.

         "Borrower" means Noble Drilling Corporation, a Delaware corporation.

         "Credit Agreement" means that certain Credit Agreement dated as of
June 16, 1994, by and among Borrower, the Agent, and the banks party thereto,
which provides for a revolving credit facility of up to $25,000,000 and for the
issuance of Letters of Credit in the face amount of up to $5,000,000.

         "Debtor Laws" means any federal, or state bankruptcy, insolvency,
reorganization, moratorium, fraudulent transfer, fraudulent conveyance,
preferential transfer or similar laws and judicial decisions, relating to or
affecting the enforcement of creditors' rights generally.

         "Guaranteed Debt" means:

         (a)     all principal, interest, reasonable attorneys' fees,
commitment fees, other fees, reimbursement obligations arising in connection
with letters of credit issued in connection with the Credit Agreement,
liabilities for costs and expenses and other indebtedness, obligations and
liabilities of Borrower to the Agent or to the Banks at any time arising under
the Credit Agreement, including, without limitation, all indebtedness,
obligations and liabilities arising under the Notes and each and every
scheduled payment of principal and/or interest as provided therein, and under
any renewals, extensions, increases, refinancings and rearrangements of the
Notes.

         (b)  all post petition interest on indebtedness, obligations and
liabilities of Borrower described in clause (a) above in the event of
bankruptcy of Borrower, or any of the Guarantors; and

         (c)     all costs, expenses and fees, including, without limitation,
court costs and reasonable attorneys' fees, arising in connection with the
enforcement or collection (whether or not any proceeding is commenced in
connection therewith) of any or all amounts, indebtedness, obligations and
liabilities of Borrower to the Agent or to the Banks described in clauses (a)
and (b) above.

         "Notes" means each of the revolving notes made by Borrower to the
order of each of the Banks, executed pursuant to the Credit Agreement.



                                      -2-
<PAGE>   3
         (b)     Capitalized items used and not otherwise defined herein shall
have the meanings set forth therefor in the Credit Agreement.

         Section 1.03.  Indebtedness Not Reduced by Offset.  The Guaranteed Debt
shall not be reduced, discharged or released because or by reason of any
existing or future offset, claim or defense of Borrower or any other Person,
against Agent or Banks or against payment of the Guaranteed Debt, whether such
offset, claim or defense arises in connection with the Guaranteed Debt (or the
transactions creating the Guaranteed Debt) or otherwise.  Without limiting the
foregoing or the Guarantors' liability hereunder, to the extent that the Agent
or any of the Banks advances funds or extends credit to Borrower, and does not
receive payments or benefits thereon in the amounts and at the time required or
provided by applicable agreements or Laws, each of the Guarantors is absolutely
liable to make such payments to (and confer such benefits on) each of the Banks
and the Agent, on a timely basis.

         Section 1.04.  "Borrower" to Include New Corporations.  The term
"Borrower" as used herein shall include any successor corporation, partnership,
association or other entity formed as a result of any reformation by, or merger
or reorganization of, Noble Drilling Corporation, a Delaware corporation.

         Section 1.05.  Payment by Guarantors.  If all or any part of the
Guaranteed Debt shall not be punctually paid when due, whether at maturity or
earlier by acceleration or otherwise, Guarantors shall, immediately upon demand
by the Agent or the Banks, and without presentment, protest, notice of protest,
notice of non-payment, notice of intention to accelerate, notice of
acceleration or any other notice whatsoever, pay in lawful money of the United
States of America, the amount due on the Guaranteed Debt to Agent at Agent's
principal office in Houston, Texas.  Such demand(s) may be made at any time
coincident with or after the time for payment of all or part of the Guaranteed
Debt is due, but not punctually paid, and may be made from time to time with
respect to the same or different items of Guaranteed Debt.  Such demand shall
be deemed made, given and received in accordance with Section 5.02 hereof.

        Section 1.06.  No Duty to Pursue Others.  It shall not be necessary for
the Agent or the Banks (and each of the Guarantors hereby waives any rights
which Guarantors may have to require the Agent or the Banks), in order to
enforce such payment by any of the Guarantors, first to (i) institute suit or
exhaust its rights against Borrower or other Persons now or hereafter liable on
the Guaranteed Debt, or any other Person, (ii) enforce the Agent's or the
Banks' rights against any security which shall ever have been given to secure
the Guaranteed Debt, (iii) enforce the Agent's or the Banks' rights against any
other guarantors of the Guaranteed Debt, (iv) join Borrower, or any other
Persons now or hereafter liable on the Guaranteed Debt in any action seeking to
enforce this Guaranty Agreement, (v) exhaust any rights available to the Agent
or to the Banks against any security or guarantor which shall ever have been
given to secure the Guaranteed Debt, or (vi) resort to any other means of
obtaining payment of the Guaranteed Debt. Neither the Agent nor the Banks shall
be required to mitigate damages or take any other action to reduce, collect or
enforce the Guaranteed Debt.





                                      -3-
<PAGE>   4
         Section 1.07.  Waiver of Notices, etc.  Each of the Guarantors agrees
to the provisions of the Notes, the Credit Agreement and the other Loan
Documents, and, except as specifically set forth in this Guaranty Agreement,
hereby waives notice of (i) any loans or advances, or the issuance of any
Letters of Credit, by the Agent or by the Banks to or at the request of
Borrower, (ii) acceptance of this Guaranty Agreement, (iii) any amendment,
modification, extension for any period, increase, refinancing or rearrangement
of the Notes or any supplement, modifications, amendment and/or restatement of
the Credit Agreement or of any of the other Loan Documents, (iv) the occurrence
of any breach by Borrower, or any Default or Event of Default, (v) the Agent's
or any of the Banks' transfer or disposition of the Guaranteed Debt, or any
part thereof, (vi) the sale or foreclosure (or posting or advertising for sale
or foreclosure) of any collateral for the Guaranteed Debt, (vii) protest, proof
of non-payment or default by Borrower, or (viii) any other action at any time
taken or omitted by the Agent or the Banks, and, generally, all demands and
notices of every kind in connection with this Guaranty Agreement, the Credit
Agreement and the other Loan Documents.

         Section 1.08.  Nature of Guaranty.  This Guaranty Agreement is an
irrevocable, absolute and continuing guaranty of payment and not a guaranty of
collection.  This Guaranty Agreement may not be revoked by any of the
Guarantors and shall continue to be effective with respect to any Guaranteed
Debt arising or created after any attempted revocation by any of the
Guarantors.  The fact that at any time or from time to time the Guaranteed Debt
may be increased, reduced or paid in full shall not release, discharge or
reduce the obligations of Guarantors with respect to the indebtedness or
obligations of Borrower, to the Agent or the Banks thereafter incurred (or
other Guaranteed Debt thereafter arising) under the Notes or otherwise.  This
Guaranty may be enforced by the Agent or the Banks and by any subsequent holder
or holders of the Guaranteed Debt and shall not be discharged by the assignment
or negotiation of all or part of the Guaranteed Debt.  Guarantors guarantee
that the Guaranteed Debt will be paid strictly in accordance with the terms of
the Notes, the Credit Agreement and the other Loan Documents, regardless of any
law of any tribunal affecting any such terms or the rights of the Agent or the
Banks with respect thereto.  The liability of the Guarantors under this
Guaranty Agreement shall be irrevocable, absolute and unconditional
irrespective of any change in the time, manner or place of payment of, or in
any other term of, all or any part of the Guaranteed Debt under the Notes, the
Credit Agreement or the other Loan Documents, or any other amendment, waiver of
or any consent to the departure from the Notes, the Credit Agreement or the
other Loan Documents.

         Section 1.09.  Payment of Expenses.  In the event that any of the
Guarantors breaches or fails to timely perform any provisions of this Guaranty
Agreement, each of the Guarantors agrees to pay to the Agent or to the Banks
all costs and expenses (including court costs and reasonable attorneys' fees)
incurred by the Agent or by the Banks in the enforcement hereof or the
preservation of the Banks' rights hereunder.  The covenant contained in this
Section 1.09 shall survive the payment of the Guaranteed Debt.




                                      -4-
<PAGE>   5
         Section 1.10.  Effect of Bankruptcy.  Pursuant to any Debtor Laws, or
any judgment, order or decision thereunder, in the event that, within four
years after the payment thereof, any of the Banks or the Agent must rescind or
restore any payment, or any part thereof, received by the any of the Banks or
the Agent in satisfaction of the Guaranteed Debt, as set forth herein, then any
prior release or discharge from the terms of this Guaranty Agreement given to
any of the Guarantors by any of the Banks or the Agent shall be without effect,
and this Guaranty Agreement shall remain in full force and effect.  Each of the
Guarantors' obligations hereunder shall not be discharged except by Guarantors'
performance of such obligations and then only to the extent of such
performance.  The covenant contained in this Section 1.10 shall survive the
payment of the Guaranteed Debt, and any portion thereof.


                                   ARTICLE II

              EVENTS AND CIRCUMSTANCES NOT REDUCING OR DISCHARGING
                          ANY GUARANTORS' OBLIGATIONS

         Each of the Guarantors hereby agrees that the liability of Guarantors
under this Guaranty Agreement is irrevocable, absolute and unconditional.  Each
of the Guarantors consents and agree to each of the following, and each of the
Guarantors further agrees that each of the Guarantors' obligations under this
Guaranty Agreement shall not be released, diminished, impaired, reduced or
adversely affected by any of the following, and waives any common law,
equitable or statutory, or other rights (including, without limitation, rights
to notice) which any such Guarantors might otherwise have as a result of or in
connection with any of the following:

         Section 2.01.  Modifications, etc.  Any renewal, extension for any
period, increase, amendment, modification, alteration, supplement or
rearrangement of all or any part of the Guaranteed Debt, the Notes, the Credit
Agreement or of any of the other Loan Documents or understandings or agreements
between Borrower, and the Agent or the Banks, or any other Persons, pertaining
to the Guaranteed Debt;

         Section 2.02.  Adjustment, etc.  Any adjustment, indulgence,
forbearance or compromise that might be granted or given by the Agent or the
Banks to Borrower, or any one or more of the Guarantors or any other guarantor
of the Guaranteed Debt;

         Section 2.03.  Condition of Borrower or Guarantors.  The insolvency,
bankruptcy, arrangement, adjustment, composition, liquidation, disability,
dissolution or lack of power of Borrower, or any other Person now or hereafter
liable for the payment of all or part of the Guaranteed Debt, including any of
the Guarantors; or any dissolution of Borrower, or any one or more of the
Guarantors or any other guarantor of the Guaranteed Debt, or any sale, lease or
transfer of any or all of the assets or properties of Borrower, or any one or
more of the Guarantors or any other guarantor of the Guaranteed Debt, or any
changes in the shareholders, partners, members or other composition of
Borrower, or any one or more of the Guarantors or any other guarantor of the
Guaranteed Debt; or any reorganization of Borrower, or any one or more of the
Guarantors or any other guarantor of the Guaranteed Debt;




                                      -5-
<PAGE>   6
         Section 2.04.  Invalidity of Guaranteed Debt.  The invalidity,
illegality or unenforceability of all or any part of the Guaranteed Debt, the
Notes, the Credit Agreement or any of the other Loan Documents, for any reason
whatsoever, including without limitation the fact that (i) the Guaranteed Debt,
or any part thereof, exceeds the amount permitted by Law, (ii) the act of
creating the Guaranteed Debt or any part thereof is ultra vires, (iii) the
officers, partners or representatives executing the Notes, the Credit Agreement
or the other Loan Documents acted in excess of their authority, (iv) the
Guaranteed Debt violates applicable usury Laws, (v) Borrower has valid
defenses, claims or offsets (whether at law, in equity or by agreement) which
render the Guaranteed Debt wholly or partially uncollectible from Borrower,
(vi) the creation, performance or repayment of the Guaranteed Debt (or the
execution, delivery and performance of any Loan Document) is illegal,
uncollectible or unenforceable, or (vii) the Notes, the Credit Agreement or any
of the other Loan Documents have been forged or otherwise are irregular or not
genuine or authentic;

         Section 2.05.  Release of Obligors.  Any full or partial release of the
liability of Borrower on the Guaranteed Debt or any part thereof, or any other
Person now or hereafter liable, whether directly or indirectly, jointly,
severally, or jointly and severally, to pay, perform, guarantee or assure the
payment of the Guaranteed Debt or any part thereof, it being recognized,
acknowledged and agreed by Guarantors that any Guarantors may be required to
pay the Guaranteed Debt in full without assistance or support of any other
Person, and none of the Guarantors has been induced to enter into this Guaranty
on the basis of a contemplation, belief, understanding or agreement that the
Agent or any of the Banks will look solely to other Persons to perform the
Guaranteed Debt;

         Section 2.06.  Other Security.  The taking or accepting of any other
security, collateral or guaranty, or other assurance of payment, for all or any
part of the Guaranteed Debt;

        Section 2.07.  Release of Collateral, etc.  Any release, surrender,
exchange, subordination, deterioration, waste, loss or impairment (including
without limitation negligent or unreasonable impairment) of any collateral,
property or security, at any time existing in connection with, or assuring or
securing payment of, all or any part of the Guaranteed Debt;

         Section 2.08.  Care and Diligence.  The failure of the Agent or the
Banks or any other party to exercise diligence or reasonable care in the
preservation, protection, enforcement, sale or other handling or treatment of
all or any part of such collateral, property or security;

         Section 2.09.  Status of Liens.  The fact that any collateral, security
or Lien contemplated or intended to be given, created or granted as security
for the repayment of the Guaranteed Debt shall not be properly perfected or
created or continuously perfected or in existence, or shall prove to be
unenforceable or subordinate to any other Lien, it being recognized and agreed
by Guarantors that none of the Guarantors is entering into this Guaranty
Agreement in reliance on, or in contemplation of the





                                      -6-
<PAGE>   7
benefits of, the validity, enforceability, collectability or value of
any collateral for the Guaranteed Debt;

         Section 2.10.  Offset.  The Guaranteed Debt guaranteed hereby, and the
liabilities and obligations of each of the Guarantors to the Agent and the
Banks hereunder, shall not be reduced, discharged or released because of or by
reason of any existing or future right of offset, recoupment, claim or defense
of Borrower against the Agent or the Banks, or any other Person, or against
payment of the Guaranteed Debt, whether such right of offset, recoupment, claim
or defense arises in connection with the Guaranteed Debt (or the transactions
creating the Guaranteed Debt) or otherwise;

         Section 2.11.  Incorporation/Merger.  The reorganization, merger or
consolidation of Borrower, into or with any other corporation, partnership or
other entity or form;

         Section 2.12.  Preference.  Any payment by Borrower, to the Agent or
the Banks is held to constitute a preference under Debtor Laws, or for any
reason the Agent or any of the Banks is required to refund such payment or pay
such amount to Borrower, or any other Person; or

         Section 2.13.  Other Actions Taken or Omitted.  Any other action taken
or omitted to be taken with respect to the Guaranteed Debt, the Notes, the
Credit Agreement or any of the other Loan Documents, or the security and
collateral therefor, whether or not such action or omission prejudices
Guarantors or increases the likelihood that Guarantors will be required to pay
the Guaranteed Debt pursuant to the terms hereof including, without limitation,
any Advances made by the Agent or the Banks to Borrower, following any Default
or Event of Default; it is the unambiguous and unequivocal intention of each of
the Guarantors that each of the Guarantors shall be absolutely obligated to pay
the Guaranteed Debt when due, notwithstanding any occurrence, circumstance,
event, action, or omission whatsoever, whether contemplated or uncontemplated,
and whether or not otherwise or particularly described herein, except for the
full and final payment and satisfaction of the Guaranteed Debt.

                                  ARTICLE III

                   REPRESENTATIONS, WARRANTIES AND COVENANTS

         To induce Banks to enter into the Credit Agreement and the other Loan
Documents and to induce Banks to make the loans and otherwise extend credit to
Borrower, each of the Guarantors represents, warrants and covenants to each of
the Agents and the Banks that:

         Section 3.01.  Familiarity and Reliance.  Each of the Guarantors is
familiar with, and has independently reviewed books and records regarding, the
financial condition of Borrower; however, none of the Guarantors are relying on
such financial condition or any collateral as an inducement to enter into this
Guaranty Agreement.




                                      -7-
<PAGE>   8
         Section 3.02.  No Representation by Banks.  Neither the Agent nor the
Banks nor any other Person has made any representation, warranty or statement
to any of the Guarantors in order to induce each of the Guarantors to execute
this Guaranty Agreement except as heretofore provided in the recitals of this
Guaranty Agreement.

         Section 3.03.  Benefit.  Each of the Guarantors is a direct or indirect
subsidiary of the Borrower, and such entity derives benefit from its
relationship with the Borrower in connection with the ownership and operation
of the business of the Borrower and its Subsidiaries, and as a result thereof,
each of the Guarantors has received, or will receive, direct or indirect
benefit and reasonably equivalent value from the making of this Guaranty
Agreement.

         Section 3.04.  Determination of Benefit.  The Board of Directors of
each of the Guarantors has determined that this Guaranty Agreement directly or
indirectly benefits each of the Guarantors and is in the best interests of each
of the Guarantors.

         Section 3.05.  Legality.  The execution, delivery and performance by
each of the Guarantors of this Guaranty Agreement and the consummation of the
transactions contemplated hereunder do not, and will not, contravene or violate
any Law to which any of the Guarantors is subject or constitute a default (or
an event which with notice or lapse of time or both would constitute a default)
under, or result in the breach of, any Lien to which any of the Guarantors is a
party or which may be applicable to each of the Guarantors or any of their
respective assets.  This Guaranty Agreement is a legal and binding obligation
of each of the Guarantors and is enforceable in accordance with its terms,
except as limited by Debtor Laws.

         Section 3.06.  Use of Proceeds; Margin Stock.  None of the proceeds
from the Loans will be used, for the purpose of purchasing or carrying any
"margin stock" as defined in Regulations G, T, U or X, or for the purpose of
maintaining, reducing or retiring any Indebtedness which was originally
incurred to purchase or carry a "margin stock" or for any other purpose which
might constitute this transaction a "purpose credit" within the meaning
of Regulations G, T, U or X.  Guarantors have not taken and will not take any
action which might cause any of the Loan Documents to violate or be subject to
Regulations G, T, U or X, or any other regulations of the Board of Governors of
the Federal Reserve System or to violate Section 8 of the Securities Exchange
Act of 1934 or any rule or regulation thereunder, in each case as now or
hereafter may be in effect at the time such proceeds were used.

         Section 3.07.  Loan Documents.  To the extent that each of the
Guarantors is a party to any of the Loan Documents, each such Loan Document is
the legal and binding obligation of such Person, enforceable in accordance with
its terms.  None of the Guarantors have or has asserted, and none are aware of,
any claims, defenses, offset rights or similar rights or remedies with respect
to, or any defect in, the Loan Documents, which in any manner or effect would
diminish or impair any rights, Liens, privileges, benefits and remedies of the
Agent or the Banks as contemplated by the Loan Documents, or would preclude the
Agent or the Banks from enforcing and collecting the Obligations in the amount
and manner as provided in the Loan Documents.  None of the Guarantors has
revoked any of its obligations under any Loan





                                      -8-
<PAGE>   9
Document to which it is a party, and none has requested and/or received
a release or termination of its obligations thereunder.  The Agent and the
Banks are authorized to rely upon all representations, warranties, statements
and other information, with respect to the Borrower and its Affiliates, set
forth in the Loan Documents, as true and correct on the date hereof.  Each of
the Guarantors hereby represents and warrants that the representations and
warranties pertaining to it as set forth in the Credit Agreement are true and
correct on the date hereof.

         Section 3.08.  Survival.  All representations and warranties made by
each of the Guarantors herein shall survive the execution hereof.


                                   ARTICLE IV

                     SUBORDINATION OF CERTAIN INDEBTEDNESS

        Section 4.01.  Subordination of All Guarantors Claims.  As used herein,
the term "Guarantors Claims" shall mean all debts and liabilities of Borrower,
to any of the Guarantors, whether such debts and liabilities now exist or are
hereafter incurred or arise, or whether the obligations of Borrower, thereon be
direct, contingent, primary, secondary, several, joint and several, or
otherwise, and irrespective of whether such debts or liabilities be evidenced
by notes, contract, open account, or otherwise, and irrespective of the person
or persons in whose favor such debts or liabilities may, at their inception,
have been, or may hereafter be created, or the manner in which they have been
or may hereafter be acquired by any of the Guarantors.  After the occurrence of
a Default, and so long thereafter as such Default continues, until the
Guaranteed Debt shall be paid and satisfied in full and the Guarantors shall
have performed all obligations hereunder, none of the Guarantors shall receive
or collect, directly or indirectly, from Borrower any amount upon the
Guarantors Claims.  The Guarantors Claims shall not include all rights and
claims of any of the Guarantors against the Borrower (arising as a result of
subrogation or otherwise) as a result of any Guarantor's payment of all or a
portion of the Guaranteed Debt.  UNTIL ALL OF THE OBLIGATIONS HAVE BEEN PAID
AND PERFORMED IN FULL, EACH OF THE GUARANTORS EXPRESSLY AND SPECIFICALLY WAIVES
ANY AND ALL RIGHTS, WHETHER ARISING BY LAW OR AGREEMENT OR OTHERWISE, TO
REIMBURSEMENT, CONTRIBUTION, SUBROGATION, EXONERATION AND INDEMNIFICATION, AND
TO PARTICIPATE IN ANY CLAIM OR REMEDY OF ANY OF THE AGENT OR THE BANKS OR ANY
OTHER PERSON AGAINST BORROWER, OR ANY OTHER PERSON, WITH RESPECT TO THE
GUARANTEED DEBT. EACH OF THE GUARANTORS HAS CONSULTED WITH LEGAL COUNSEL OF ITS
OWN CHOOSING AS TO THE EFFECT OF THE FOREGOING WAIVERS.  If any Guarantor shall
make payment to Lender of all or any portion of the Obligations, and if all of
the Obligations shall be finally paid in full, Agent will, at such Guarantor's
request and expense, execute and deliver to such Guarantor (without recourse,
representation or warranty) appropriate documents necessary to evidence the
transfer by subrogation to such Guarantor of an interest in the Obligations
resulting from such payment by such Guarantor; provided that such transfer
shall be subject to Section 1.10 above.





                                      -9-
<PAGE>   10
         Section 4.02.  Claims in Bankruptcy.  In the event of receivership,
bankruptcy, reorganization, arrangement, debtor's relief, or other insolvency
proceedings involving Borrower as debtor, the Agent and the Banks shall have
the right to prove the claims of the Banks (and of the Agent, if any) in any
such proceeding so as to establish its rights hereunder and receive directly
from the receiver, trustee or other court custodian dividends, distributions
and payments which would otherwise be payable upon Guarantors Claims.  Each of
the Guarantors hereby assigns such dividends, distributions and payments to the
Agent for the benefit of the Banks.  Should the Agent or the Banks receive, for
application upon the Guaranteed Debt, any such dividend or payment which is
otherwise payable to any of the Guarantors, and which, as between Borrower and
Guarantors, shall constitute a credit upon the Guarantors Claims, then upon
payment to Banks in full of the Guaranteed Debt, each of the Guarantors shall
become subrogated to the rights of the Agent and the Banks to the extent that
such payments to the Agent and the Banks on the Guarantors Claims have
contributed toward the liquidation of the Guaranteed Debt, and such subrogation
shall be with respect to that proportion of the Guaranteed Debt which would
have been unpaid if Agent and the Banks had not received dividends or payments
upon the Guarantors Claims.

        Section 4.03.  Payments Held in Trust.  In the event that,
notwithstanding Sections 4.01 and 4.02 above, any of the Guarantors should
receive any funds, payment, claim or distribution which is prohibited by such
Sections, each of the Guarantors, unless otherwise directed in writing by the
Agent or the Banks, agree to immediately notify the Agent of receipt of same
and to hold in trust for the Banks an amount equal to the amount of all funds,
payments, claims or distributions so received, and agree that it shall have
absolutely no dominion over the amount of such funds, payments, claims or
distributions, except to pay them promptly to the Agent for the benefit of the
Banks, and Guarantors covenant to immediately pay the same to the Agent for the
benefit of the Banks.

         Section 4.04.  Liens Subordinate.  Each of the Guarantors agrees that
any Liens upon the assets and properties of Borrower, securing payment of the
Guarantors Claims shall be and remain inferior and subordinate to any Liens
upon the assets and properties of Borrower securing payment of the Guaranteed
Debt, regardless of whether such Liens in favor of any of the Guarantors or the
Agent for the benefit of the Banks presently exist or are hereafter created or
attach.  Without the prior written consent of the Agent, none of the Guarantors
shall (i) exercise or enforce any rights it may have against Borrower, or (ii)
foreclose, repossess, sequester or otherwise take steps or institute any action
or proceedings (judicial or otherwise, including without limitation the
commencement of, or joinder in, any liquidation, bankruptcy, rearrangement,
debtor's relief or insolvency proceeding) to enforce any Liens on assets of
Borrower, held by any of the Guarantors.






                                      -10 -
<PAGE>   11
                                   ARTICLE V

                                 MISCELLANEOUS

         Section 5.01.  Waiver.  No failure to exercise, and no delay in
exercising, on the part of the Agent or the Banks, any right hereunder shall
operate as a waiver thereof, nor shall any single or partial exercise thereof
preclude any other or further exercise thereof or the exercise of any other
right.  The rights of the Agent and the Banks hereunder shall be in addition to
all other rights provided by law.  No modification or waiver of any provision
of this Guaranty Agreement, nor consent to departure therefrom, shall be
effective unless in writing and signed by Banks and no such consent or waiver
shall extend beyond the particular case and purpose involved.  No notice or
demand given in any case shall constitute a waiver of the right to take other
action in the same, similar or other instances without such notice or demand.

        Section 5.02.  Notices.  Except for telephonic notices permitted
herein, any notices or other communications required or permitted to be given
by this Agreement or any other Loan Documents and instruments referred to
herein must be (i) given in writing and personally delivered or mailed by
prepaid certified or registered mail, or (ii) made by telex or telecopy
delivered or transmitted, to the party to whom such notice of communication is
directed, to the address of such party as follows:  (a) if to Guarantors, c/o
Noble Drilling Corporation, 10370 Richmond Avenue, Suite 400, Houston, Texas
77042, Fax Number: (713) 974-3181, Attention:  Byron L. Welliver, Sr. Vice
President - Finance and Treasurer, with copy to Thompson & Knight, a
Professional Corporation, 1700 Pacific Avenue, Suite 3300, Dallas, Texas 75201,
Fax Number: (214) 969-1751, Attention: Robert D. Campbell, Esq.; and (b) if to
Agent, as set forth therefor in the Credit Agreement, and if to the Banks, then
in care of the Agent, all with copy to Fulbright & Jaworski L.L.P., 1301
McKinney, Suite 5100, Houston, Texas 77010, Fax Number: (713) 651-5246,
Attention: Joshua P. Agrons; provided however, the failure of any of the
Guarantors, Agent or the Banks to provide a copy of any notice or other
communication to the other party's counsel as specified in the foregoing clause
shall not affect the effectiveness, legitimacy and significance of any notice
or other communication sent by any of the Guarantors to the Agent or the Banks,
or the Agent of any of the Guarantors, so long as such notice or other
communication is otherwise in compliance with this Section 5.02.  Any notice to
be mailed or personally delivered may be mailed or delivered to the principal
offices of the party to whom such notice is addressed.  Any such notice or
other communication shall be deemed to have been given (whether actually
received or not) on the day it is mailed or personally delivered as aforesaid
or, if transmitted by telex, on the day that such notice is transmitted as
aforesaid; provided, however, that any telephonic or other notice received by a
party after 11:00 a.m. (Houston, Texas time) on any day shall be deemed to have
been given on the next succeeding day. Any party may change its address for
purposes of this Agreement by giving notice of such change to the other party
pursuant to this Article 5.02.




                                      -11-

<PAGE>   12
         Section 5.03.  Entirety and Amendments.  This Guaranty Agreement
embodies the entire agreement between the parties and supersedes all prior
agreements and understandings, if any, relating to the subject matter hereof
and this Guaranty Agreement may be amended only by an instrument in writing
executed by the parties hereto.

         Section 5.04.  Parties Bound; Assignment.  This Guaranty Agreement
shall be binding upon and inure to the benefit of the parties hereto and their
respective successors, assigns and legal representatives; provided, however,
none of the Guarantors may, without the prior written consent of the Agent,
assign any of its rights, duties or obligations hereunder.

         Section 5.05.  Multiple Parties.  Anyone signing this Guaranty
Agreement shall be bound thereby, whether or not any other party signs this
Guaranty Agreement or is released therefrom at any time.  It is specifically
agreed that the Agent may enforce the provisions hereof with respect to one or
more of the Guarantors without seeking to enforce the same as to all or any
other such parties, and each of the Guarantors hereby waives any requirement of
joinder of all or any other of the other parties hereto in any suit or
proceeding to enforce the provisions hereof.  The obligations created by this
Guaranty Agreement shall be joint and several (and not merely joint) with
respect to each of the Guarantors.

         Section 5.06.  Headings.  Section headings are for convenience of
reference only and shall in no way affect the interpretation of this Guaranty
Agreement.

        Section 5.07.  Rights and Remedies.  If any of the Guarantors becomes
liable for any indebtedness owing by any of the Borrower to the Agent or to the
Banks, by endorsement or otherwise, other than under this Guaranty Agreement,
such liability shall not be in any manner impaired or affected hereby and the
rights of the Agent and the Banks hereunder shall be cumulative of any and all
other rights of the Agent or the Banks hereunder that Banks may have against
any of the Guarantors.  The exercise by the Agent or the Banks of any right
under this Guaranty Agreement, the Credit Agreement, any of the other Loan
Documents, any other instrument, document or agreement, or at law or in equity,
shall not preclude the concurrent or subsequent exercise of any other right.

         Section 5.08.  Multiple Counterparts.  This Guaranty Agreement may be
executed in any number of counterparts, all of which taken together shall
constitute one and the same agreement, and any of the parties hereto may
execute this Guaranty Agreement by signing any such counterpart.

         Section 5.09.  Choice of Law.  THIS GUARANTY SHALL BE CONSTRUED IN
ACCORDANCE WITH AND GOVERNED BY THE INTERNAL LAWS OF THE STATE OF TEXAS.

         Section 5.10.  Submission to Jurisdiction.  To the extent not expressly
prohibited by law from time to time in effect, each of the Guarantors hereby
irrevocably and unconditionally:  (i) submits for itself and its property in
any legal action or proceeding




                                      -12-
<PAGE>   13
relating to this Guaranty Agreement or for
recognition and enforcement of any judgment in respect thereof, to the
non-exclusive general jurisdiction of the Courts of Harris County, Texas, the
Courts of the United States of America for the Southern District of Texas,
Houston Division and Appellate Courts from any thereof; (ii) consents that any
such action or proceeding may be brought in such courts, and waives any
objection that it may now or hereafter have to the venue of any such action or
proceeding in any such court or that any such action or proceeding was brought
in an inconvenient court and agrees not to plead or claim the same; (iii)
agrees that service of process in any such action or proceeding may be effected
by mailing a copy thereof by registered or certified mail (or any substantially
similar form of mail), postage prepaid, to Guarantor at its address set forth
in Section 5.02 of this Guaranty Agreement or at such other address of which
Agent shall have been notified pursuant thereto; and (iv) agrees that nothing
herein shall impair the right of Agent to effect service of process in any
other manner permitted by law or shall limit the right to sue in any other
jurisdiction.

         EXECUTED effective as of the day and year first above written.

                                  GUARANTORS:


                                  NOBLE DRILLING (U.S.), INC.


                                  By:  /s/ BYRON L. WELLIVER
                                     ________________________________________
                                           Byron L. Welliver 
                                         Senior Vice President     


                                  NOBLE DRILLING (WEST AFRICA), INC.


                                  By:  /s/ BYRON L. WELLIVER
                                     ________________________________________
                                           Byron L. Welliver 
                                         Senior Vice President      


                                  NOBLE DRILLING (MEXICO), INC.


                                  By:  /s/ ALAN KRENEK
                                     ________________________________________
                                           Alan Krenek
                                            Treasurer



                                      -13-

<PAGE>   1



                                            EXHIBIT 12.1

                             NOBLE DRILLING CORPORATION AND SUBSIDIARIES
                     STATEMENT OF COMPUTATION OF EARNINGS (DEFICIENCY) AVAILABLE
                                       TO COVER FIXED CHARGES
                                             (Unaudited)
                                            (In thousands)

<TABLE>
<CAPTION>
                                                   Three months 
                                                      ended
                                                    March 31,                      Year ended December 31,
                                                 ------------------    -----------------------------------------------------
                                                  1994       1993       1993        1992       1991       1990        1989
                                                 -------    -------    -------    --------    --------   -------    -------

<S>                                              <C>        <C>        <C>        <C>         <C>         <C>        <C>
Noble-Historical                
Earnings available for fixed charges:
  Income (loss) from continuing operations      
    before income taxes and extraordinary items  $ 5,670    $ 4,244    $21,620    $ (5,844)   $(11,285)   $(7,541)   $ (9,286)
Add-fixed charges                                  3,052      1,087      5,715       8,148      14,994      3,450       3,110
Deduct-capitalized interest                                                                    (1,054)      (614)
                                                 -------    -------    -------    --------    --------    -------    --------
      Total                                        8,722      5,331     27,335       2,304       2,655     (4,705)     (6,176)
                                                 -------    -------    -------    --------    --------    -------    --------
Fixed charges:
  Interest and related costs                       2,921      1,010      5,314       7,140      13,408      3,061       2,781
  Amortization of debt expense                        79                    92         678       1,140
  Rental expense factor representative
    of interest factor                                52         77        309         330         446        389         329
                                                 -------    -------    -------    --------    --------    -------    --------
      Total                                        3,052      1,087      5,715       8,148      14,994      3,450       3,110
                                                 -------    -------    -------    --------    --------    -------    --------
Ratio of earnings to fixed charges                  2.86       4.90       4.78
Deficiency of earnings available to cover
  combined fixed charges                         $          $          $          $  5,844    $ 12,339    $ 8,155    $  9,286
                                                 =======    =======    =======    ========    ========    =======    ========

Chiles-Historical
Earnings available for fixed charges:
  Income (loss) from continuing operations
    before income taxes and extraordinary items  $ 3,995    $(3,483)   $ 2,795    $(30,738)   $(25,472)   $(2,762)   $(10,531)
Add-fixed charges                                     51        879      3,233       6,384       8,412      4,865       8,343
Deduct-capitalized interest                                                                                  (302)
                                                 -------    -------    -------    --------    --------    -------    --------
                                                   4,046     (2,604)     6,028     (24,354)    (17,060)     1,801      (2,188)
                                                 -------    -------    -------    --------    --------    -------    --------
Fixed charges:
  Interest and related costs                                    809      2,632       5,456       6,917      4,218       8,199
  Amortization of debt expense                                             332         642         758         45          23
  Rental expense factor representative of
    interest factor                                   51         70        269         286         737        602         121
                                                 -------    -------    -------    --------    --------    -------    --------
                                                      51        879      3,233       6,384       8,412      4,865       8,343
                                                 -------    -------    -------    --------    --------    -------    --------
Ratio of earnings to fixed charges                 79.33                  1.86                                      
Deficiency of earnings available to cover
  combined fixed charges                         $          $ 3,483    $          $ 30,738    $ 25,472    $ 3,064    $ 10,531
                                                 =======    =======    =======    ========    ========    =======    ========

</TABLE>

<PAGE>   2

<TABLE>
<CAPTION>


                                                   Three months 
                                                      ended
                                                    March 31,               Year ended December 31,
                                                 ------------------    --------------------------------
                                                  1994       1993       1993        1992       1991    
                                                 -------    -------    -------    --------    -------- 
                                                                                                       
<S>                                              <C>        <C>        <C>        <C>         <C>      
Noble and Chiles-Pro Forma Combined                                                                    
Earnings available for fixed charges:
  Income (loss) from continuing operations
    before income taxes and extraordinary items  $ 9,665    $   761    $24,415    $(36,282)   $(36,757)
Add-fixed charges                                  3,103      1,966      8,948      14,532      23,406
Deduct-capitalized interest                                                                     (1,054)
                                                 -------    -------    -------    --------    --------  
      Total                                       12,768      2,727     33,363     (21,750)    (14,405)
                                                 -------    -------    -------    --------    --------  
Fixed charges:
  Interest and related costs                       2,921      1,819      7,946      12,596      20,325
  Amortization of debt expense                        79                   424       1,320       1,898
  Rental expense factor representative of
    interest factor                                  103        147        578         616       1,183
                                                 -------    -------    -------    --------    --------  
      Total                                        3,103      1,966      8,948      14,532      23,406
                                                 -------    -------    -------    --------    --------  
Ratio of earnings to fixed charges                  4.11       1.39       3.73
Deficiency of earnings available to cover
    combined fixed charges                       $          $          $          $ 36,282    $ 37,811
                                                 =======    =======    =======    ========    ======== 
Noble (A), Chiles and Triton-Pro Forma Combined
Earnings available for fixed charges:
  Income (loss) from continuing operations
    before income taxes and extraordinary items  $10,570               $24,003
Add-fixed charges                                  3,188                17,032
Deduct-capitalized interest
                                                 -------               ------- 
      Total                                       13,758                41,035
                                                 -------               ------- 
Fixed charges:
  Interest and related costs                       2,921                15,554
  Amortization of debt expense                        79                   424
  Rental expense factor representative of
    interest factor                                  188                 1,054
                                                 -------               ------- 
      Total                                        3,188                17,032
                                                 -------               ------- 
Ratio of earnings to fixed charges                  4.32                  2.41
Deficiency of earnings available to cover
  combined fixed charges                         $                     $
                                                 =======               =======

</TABLE>

     A)  Noble historical amounts were adjusted to include the effects of the
         Western Acquisition as if it had occurred on January 1, 1993.

<PAGE>   1
 
                   CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
     As independent public accountants, we hereby consent to the incorporation
by reference in this Registration Statement of our report dated January 27, 1994
related to the audited consolidated historical financial statements of Noble
Drilling Corporation and subsidiaries and the related schedules included in the
Noble Drilling Corporation Form 10-K for the year ended December 31, 1993 and
incorporated by reference in this Registration Statement, and to all references
to our Firm included in this Registration Statement.



/s/  ARTHUR ANDERSEN & CO.

 
Houston, Texas
July 8, 1994

<PAGE>   1
 
                   CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
     As independent public accounts, we hereby consent to the incorporation by
reference in this Registration Statement of our report dated February 7, 1994
(except with respect to the matter discussed in Note 9, as to which the date is
March 24, 1994) related to the audited consolidated financial statements of
Chiles Offshore Corporation and subsidiaries and the related schedules included
in the Chiles Offshore Corporation Form 10-K for the year ended December 31,
1993 and incorporated by reference in this Registration Statement, and to all
references to our Firm included in this Registration Statement.

 
/s/  ARTHUR ANDERSEN & CO.

 
Houston, Texas
July 8, 1994

<PAGE>   1
                                                                  Exhibit 23.3


                CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS


We consent to the incorporation by reference in the registration statement on
Form S-4 filed by Noble Drilling Corporation of our report dated March 4, 1994,
with respect to the consolidated balance sheets of Triton Engineering Services
Company and subsidiaries as of December 31, 1993 and 1992, and the related
consolidated statements of income, stockholders' equity and cash flows for each
of the years in the two-year period ended December 31, 1993, which report
appears in the Form 8-K of Noble Drilling Corporation dated June 30, 1994.


/s/  KPMG Peat Marwick

 
Houston, Texas
July 8, 1994



<PAGE>   1
                                                                  EXHIBIT 23.6

                  CONSENT OF SIMMONS & COMPANY INTERNATIONAL


        We hereby consent to the use of our name, to the summarization of our
letter dated June 13, 1994 and to the other references to us in the Joint
Proxy Statement/Prospectus of Noble Drilling Corporation and Chiles Offshore
Corporation, and to the inclusion of such letter as Appendix II to such Joint
Proxy Statement/Prospectus, which Joint Proxy Statement/Prospectus is part of
this Registration Statement on Form S-4 of Noble Drilling Corporation. By
giving such consent, we do not thereby admit that we are experts with respect
to any part of such Registration Statement within the meaning of the term
"expert" as used in the Securities Act of 1933, as amended, or the rules and
regulations of the Securities and Exchange Commission promulgated thereunder,
or are within the class of persons whose consent is required thereunder.


                                           SIMMONS & COMPANY INTERNATIONAL 


                                           By     /s/  Nicholas L. Swyka
                                             ----------------------------------
                                                      Managing Director

Houston, Texas
July 8, 1994



<PAGE>   1
                                                                  EXHIBIT 23.7

SALOMON BROTHERS INC                                   SALOMON BROTHERS
Seven World Trade Center
New York, New York 10048
212-783-7000


                       CONSENT OF SALOMON BROTHERS INC


        We hereby consent to the use of our name, to the summarization of our
letter dated June 13, 1994 and to the other references to us in the Joint Proxy
Statement/Prospectus of Noble Drilling Corporation and Chiles Offshore
Corporation, and to the inclusion of such letter as Appendix III to such Joint
Proxy Statement/Prospectus, which Joint Proxy Statement/Prospectus is part of
this Registration Statement on Form S-4 of Noble Drilling Corporation. By
giving such consent, we do not thereby admit that we are experts with respect
to any part of such Registration Statement within the meaning of the term
"expert" as used in the Securities Act of 1933, as amended, or the rules and
regulations of the Securities and Exchange Commission promulgated thereunder,
or are within the class of persons whose consent is required thereunder.


                                           SALOMON BROTHERS INC 


                                           /s/  SALOMON BROTHERS INC

New York, New York
July 8, 1994



<PAGE>   1
                                                                    EXHIBIT 99.1

[NOBLE LOGO]

                                  [Proxy Card]


                           NOBLE DRILLING CORPORATION

          THIS PROXY IS SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS

         The undersigned hereby appoints James C. Day and Byron L. Welliver,
and each of them, proxies with power of substitution in each, and hereby
authorizes them to represent and to vote, as designated below, all shares of
Common Stock ("Common Stock") of Noble Drilling Corporation (the "Company")
standing in the name of the undersigned on ____________, 1994, at the special
meeting of stockholders to be held on ____________, 1994 at 10:00 a.m., local
time, at Houston, Texas, and at any adjournment thereof and especially to vote
on the items of business specified below, as more fully described in the notice
of the meeting and the proxy statement accompanying the same, receipt of which
is hereby acknowledged.

1.   FOR ( )      AGAINST ( )      ABSTAIN ( )    Approval of (a) the Agreement 
                                                  and Plan of Merger (the 
                                                  "Merger Agreement"), as more 
                                                  fully described in the 
                                                  accompanying Joint Proxy
                                                  Statement/Prospectus, and
                                                  pursuant to which, among 
                                                  other things, (i) Chiles
                                                  Offshore Corporation 
                                                  ("Chiles") would merge with
                                                  and into a newly formed,
                                                  wholly owned subsidiary of 
                                                  the Company and (ii) each
                                                  issued and outstanding share
                                                  of Common Stock of Chiles
                                                  would be converted into the
                                                  right to receive 0.75 of a
                                                  share of Common Stock of the
                                                  Company and each issued and
                                                  outstanding share of $1.50
                                                  Convertible Preferred Stock
                                                  of Chiles would be converted
                                                  into the right to receive one
                                                  share of a new series of 
                                                  $1.50 Convertible Preferred
                                                  Stock of the Company, and (b)
                                                  the issuance of shares of
                                                  Common Stock of the Company
                                                  and the new series of $1.50
                                                  Convertible Preferred Stock
                                                  of the Company pursuant to
                                                  the Merger Agreement.

2.   FOR ( )      AGAINST ( )      ABSTAIN ( )    Adoption of the amendment to
                                                  the Company's Restated
                                                  Certificate of Incorporation
                                                  to increase the number of
                                                  authorized shares of Common
                                                  Stock from 75,000,000 to
                                                  200,000,000.

3.   FOR ( )      AGAINST ( )      ABSTAIN ( )    Approval of amendments to the 
                                                  Noble Drilling Corporation 
                                                  1991 Stock Option and 
                                                  Restricted Stock Plan to (i) 
                                                  increase from 1,900,000 to 
                                                  5,200,000 the aggregate 
                                                  number of shares of Common
                                                  Stock available for issuance
                                                  thereunder, (ii) limit to
                                                  2,600,000 the total number of
                                                  shares of Common Stock that
                                                  may be made subject to grants
                                                  of options and stock 
                                                  appreciation rights or awards
                                                  of restricted stock under the
                                                  Plan to any one person and
                                                  (iii) provide for 
                                                  administration of the Plan by
                                                  directors who are "outside"
                                                  directors within the meaning
                                                  of federal tax laws.

4.   In their discretion, the proxies are authorized to vote upon such other
     business or matters as may properly come before the meeting or any
     adjournment thereof.

                  (CONTINUED AND TO BE SIGNED ON REVERSE SIDE)
<PAGE>   2
                            [Reverse of Proxy Card]

         THIS PROXY, WHEN DULY EXECUTED AND RETURNED, WILL BE VOTED IN THE
MANNER DESIGNATED HEREIN BY THE UNDERSIGNED STOCKHOLDER.  IF THIS PROXY IS DULY
EXECUTED AND RETURNED, BUT WITHOUT A CLEAR VOTING DESIGNATION, IT WILL BE VOTED
FOR ITEMS 1, 2 and 3.

         The undersigned hereby revokes any proxy or proxies heretofore given
to represent or vote such Common Stock and hereby ratifies and confirms all
actions that said proxies, their substitutes, or any of them, may lawfully take
in accordance with the terms hereof.



                                   Dated:_________________________________, 1994

                                   _____________________________________________

                                   _____________________________________________
                                   Signature(s) of Stockholder(s)

                                   This proxy should be signed exactly as your 
                                   name appears hereon.  Joint owners should 
                                   both sign.  If signed as attorney, executor, 
                                   guardian or in some other representative
                                   capacity, or as officer of a corporation, 
                                   please indicate your capacity or title.

                                   PLEASE COMPLETE, DATE AND SIGN THIS PROXY 
                                   AND RETURN IT PROMPTLY IN THE ENCLOSED 
                                   ENVELOPE, WHICH REQUIRES NO POSTAGE IF 
                                   MAILED IN THE UNITED STATES.

<PAGE>   1
                             FRONT SIDE OF PROXY

                                    PROXY
                         CHILES OFFSHORE CORPORATION
             SPECIAL MEETING OF SHAREHOLDERS - ____________, 1994
                  PROXY SOLICITED BY THE BOARD OF DIRECTORS

     The undersigned hereby appoints C. Ray Bearden and Robert F. Fulton as
Proxies, each with the power to appoint his substitute, and hereby authorizes
each of them to represent and to vote as designated below, all the shares of
Common Stock of Chiles Offshore Corporation, held of record by the undersigned
on ___________, 1994, at the Special Meeting of Shareholders of Chiles Offshore
Corporation to be held on ____________, 1994 in the ____________ Room of the
______________ at _______________, commencing at 10:00 a.m., local time, or any
adjournment or postponement thereof.

     The undersigned hereby revokes any proxy to vote said shares heretofore
given.  THE UNDERSIGNED ACKNOWLEDGES THAT THIS PROXY, WHEN PROPERLY EXECUTED,
WILL BE VOTED IN THE MANNER DIRECTED HEREIN BY THE UNDERSIGNED SHAREHOLDER AND
THAT IF NO DIRECTION IS MADE, THIS PROXY WILL BE VOTED IN FAVOR OF PROPOSAL 1.

     Please sign exactly as name appears on your stock certificates.  When
shares are held by joint tenants, both should sign.  When signing as attorney,
executor, administrator, trustee or guardian, please give full title as such. 
If a corporation, please sign in full corporate name by the President or an 
other authorized officer.  If a partnership, please sign in partnership name by
an authorized person.

     I plan to attend the meeting (Please check if yes)     (  )

1.   Authorization, approval and adoption of the Agreement and Plan of Merger
     dated June 13, 1994, pursuant to which Chiles Offshore Corporation will be
     merged with and into wholly owned subsidiary of Noble Drilling Corporation.

           (  )  FOR        (  )  AGAINST          (  )  ABSTAIN

                         (continued on reverse side)

<PAGE>   2
                              BACK SIDE OF PROXY

2.     IN THEIR DISCRETION, THE PROXIES ARE AUTHORIZED TO VOTE UPON SUCH OTHER
       BUSINESS AS MAY PROPERLY COME BEFORE THE MEETING, OR ANY ADJOURNMENT OR
       POSTPONEMENT THEREOF.


                                    If you receive more than one proxy card,
                                    please sign and return all cards in the
                                    accompanying envelope.

                                                 Date ____________________, 1994

                                                 _______________________________
                                                           Signature

                                                 _______________________________
                                                    Signature if held jointly


This proxy may be revoked at any time prior to the voting of the proxy by the
execution and submission of a revised proxy, by written notice to the Secretary
of the Company or by voting in person at the meeting.


                  PROXY SOLICITED BY THE BOARD OF DIRECTORS
                PLEASE MARK, SIGN, DATE AND RETURN THIS PROXY
                     PROMPTLY USING THE ENCLOSED ENVELOPE



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