HOUSTON EXPLORATION CO
424B3, 1998-05-15
OIL & GAS FIELD EXPLORATION SERVICES
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<PAGE>   1

                                               Filed Pursuant to Rule 424(b)(3) 
                                                     Registration No. 333-50235
 
PROSPECTUS
 
                        THE HOUSTON EXPLORATION COMPANY
 
                               OFFER TO EXCHANGE
 $1,000 PRINCIPAL AMOUNT OF 8 5/8% SENIOR SUBORDINATED NOTES DUE 2008, SERIES B
                FOR EACH $1,000 PRINCIPAL AMOUNT OF OUTSTANDING
              8 5/8% SENIOR SUBORDINATED NOTES DUE 2008, SERIES A
            ($100,000,000 IN AGGREGATE PRINCIPAL AMOUNT OUTSTANDING)
                             ---------------------
 
                  THE EXCHANGE OFFER WILL EXPIRE AT 5:00 P.M.,
             NEW YORK CITY TIME, ON JUNE 14, 1998, UNLESS EXTENDED
                             ---------------------
 
     The Houston Exploration Company, a Delaware corporation (the "Company"),
hereby offers, upon the terms and subject to the conditions set forth in this
Prospectus and the accompanying Letter of Transmittal, to exchange $1,000
principal amount of its 8 5/8% Senior Subordinated Notes Due 2008, Series B (the
"Exchange Notes"), in a transaction registered under the Securities Act of 1933,
as amended (the "Securities Act"), pursuant to a Registration Statement (as
defined herein) of which this Prospectus constitutes a part, for each $1,000
principal amount of the outstanding 8 5/8% Senior Subordinated Notes due 2008,
Series A (the "Old Notes"), of which $100,000,000 aggregate principal amount is
outstanding (the "Exchange Offer"). The Exchange Notes and the Old Notes are
sometimes referred to herein collectively as the "Notes."
 
     The Company will accept for exchange any and all Old Notes that are validly
tendered and not withdrawn prior to 5:00 p.m., New York City time, on the date
the Exchange Offer expires, which will be June 14, 1998 unless the Exchange
Offer is extended (the "Expiration Date"). Tenders of Old Notes may be withdrawn
at any time prior to 5:00 p.m., New York City time, on the Expiration Date. The
Exchange Offer is not conditioned upon any minimum principal amount of Old Notes
being tendered for exchange. However, the Exchange Offer is subject to certain
conditions that may be waived by the Company and to the terms and provisions of
the Registration Rights Agreement (as defined herein). See "The Exchange Offer."
Old Notes may be tendered only in denominations of $1,000 and integral multiples
thereof. The Company has agreed to pay the expenses of the Exchange Offer. There
will be no cash proceeds to the Company from the Exchange Offer. See "Use of
Proceeds."
 
     The Exchange Notes will be obligations of the Company entitled to the
benefits of the indenture relating to the Notes (the "Indenture"). The form and
terms of the Exchange Notes are identical in all material respects to the form
and terms of the Old Notes, except that (i) the offering of the Exchange Notes
has been registered under the Securities Act, (ii) the Exchange Notes will not
be subject to transfer restrictions and (iii) the Exchange Notes will not be
entitled to registration or other rights under the Registration Rights Agreement
(as defined herein) including the provision in the Registration Rights Agreement
for payment of Liquidated Damages (as defined in the Registration Rights
Agreement) upon failure by the Company to consummate the Exchange Offer or the
occurrence of certain other events. Following the Exchange Offer, any holders of
Old Notes will continue to be subject to the existing restrictions on transfer
thereof and, as a general matter, the Company will not have any further
obligation to such holders to provide for registration under the Securities Act
of transfers of the Old Notes held by them. To the extent that Old Notes are
tendered and accepted in the Exchange Offer, a holder's ability to sell
untendered and tendered but unaccepted Old Notes could be adversely affected.
See "The Exchange Offer -- Purpose and Effect of the Exchange Offer."
 
                                                        (continued on next page)
                             ---------------------
 
     SEE "RISK FACTORS" BEGINNING ON PAGE 16 FOR A DISCUSSION OF CERTAIN FACTORS
INVESTORS SHOULD CONSIDER IN CONNECTION WITH THE EXCHANGE OFFER AND AN
INVESTMENT IN THE EXCHANGE NOTES OFFERED HEREBY.
                             ---------------------
 
  THESE SECURITIES 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 PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
                               CRIMINAL OFFENSE.
                             ---------------------
 
                  The date of this Prospectus is May 15, 1998.
<PAGE>   2
 
     The Old Notes were sold by the Company on March 2, 1998, to Donaldson,
Lufkin & Jenrette Securities Corporation, Salomon Brothers Inc, PaineWebber
Incorporated, Chase Securities Inc. and Howard, Weil, Labouisse, Friedrichs
Incorporated (the "Initial Purchasers") in transactions not registered under the
Securities Act in reliance upon the exemption provided in Section 4(2) of the
Securities Act (the "Offering"). The Initial Purchasers placed the Old Notes
with qualified institutional buyers (as defined in Rule 144A under the
Securities Act) ("Qualified Institutional Buyers" or "QIBs"), each of whom
agreed to comply with certain transfer restrictions and other restrictions.
Accordingly, the Old Notes may not be reoffered, resold or otherwise transferred
in the United States unless such transaction is registered under the Securities
Act or an applicable exemption from the registration requirements of the
Securities Act is available. The Exchange Notes are being offered hereby in
order to satisfy the obligations of the Company under a registration rights
agreement among the Company and the Initial Purchasers relating to the Old Notes
(the "Registration Rights Agreement").
 
     The Exchange Notes will bear interest at a rate of 8 5/8% per annum,
payable semi-annually on January 1 and July 1 of each year, commencing July 1,
1998. Holders of Exchange Notes of record on June 15, 1998 will receive on July
1, 1998 an interest payment in an amount equal to (x) the accrued interest on
such Exchange Notes from the date of issuance thereof to July 1, 1998, plus (y)
the accrued interest on the previously held Old Notes from the date of issuance
of such Old Notes (March 2, 1998) to the date of exchange thereof. Interest will
not be paid on Old Notes that are accepted for exchange. The Notes mature on
January 1, 2008.
 
     The Old Notes were initially represented by three global Old Notes (the
"Global Old Notes") in registered form, registered in the name of Cede & Co., as
nominee for The Depository Trust Company ("DTC" or the "Depositary"), as
depositary. The Exchange Notes exchanged for Old Notes represented by the Global
Old Notes will be initially represented by a single global Exchange Note (the
"Global Exchange Note") in registered form, registered in the name of the
Depositary. See "Description of the Notes -- Book-Entry; Delivery; Form and
Transfer." References herein to "Global Notes" shall be references to the Global
Old Notes and the Global Exchange Note.
 
     Based on an interpretation of the Securities Act by the staff of the
Securities and Exchange Commission (the "SEC"), Exchange Notes issued pursuant
to the Exchange Offer in exchange for Old Notes may be offered for resale,
resold and otherwise transferred by a holder thereof (other than (i) a
broker-dealer who purchased such Old Notes directly from the Company for resale
pursuant to Rule 144A or any other available exemption under the Securities Act
or (ii) a person that is an "affiliate" (within the meaning of Rule 405 of the
Securities Act) of the Company), without compliance with the registration and
prospectus delivery provisions of the Securities Act, provided that the holder
is acquiring the Exchange Notes in its ordinary course of business and is not
participating, and has no arrangement or understanding with any person to
participate, in the distribution of the Exchange Notes. Holders of Old Notes
wishing to accept the Exchange Offer must represent to the Company that such
conditions have been met.
 
     Each broker-dealer that receives Exchange Notes for its own account
pursuant to the Exchange Offer must agree that it will deliver a prospectus in
connection with any resale of such Exchange Notes. The Letter of Transmittal
states that by so acknowledging and by delivering a prospectus, a broker-dealer
will not be deemed to admit that it is an "underwriter" within the meaning of
the Securities Act. This Prospectus, as it may be amended or supplemented from
time to time, may be used by a broker-dealer in connection with resales of
Exchange Notes received in exchange for Old Notes where such Old Notes were
acquired by such broker-dealer as a result of market-making activities or other
trading activities. The Company has agreed that, for a period of up to 180 days
after the Expiration Date, it will make this Prospectus available to any broker-
dealer for use in connection with any such resale. See "Plan of Distribution."
 
     The Exchange Notes will be a new issue of securities for which there
currently is no market. The Company does not intend to apply for listing or
quotation of the Exchange Notes on any securities exchange or stock market.
Although one of the Initial Purchasers has informed the Company that it
currently intends to make a market in the Exchange Notes, it is not obligated to
do so, and any such market-making may be discontinued at any time without
notice. Accordingly, there can be no assurance as to the development, liquidity
or maintenance of any market for the Exchange Notes. See "Risk Factors."
<PAGE>   3
 
     NO DEALER, SALESPERSON OR OTHER INDIVIDUAL HAS BEEN AUTHORIZED TO GIVE ANY
INFORMATION OR TO MAKE ANY REPRESENTATIONS NOT CONTAINED IN THIS PROSPECTUS IN
CONNECTION WITH THE EXCHANGE OFFER COVERED BY THIS PROSPECTUS. IF GIVEN OR MADE,
SUCH INFORMATION OR REPRESENTATIONS MUST NOT BE RELIED UPON AS HAVING BEEN
AUTHORIZED BY THE COMPANY. THIS PROSPECTUS DOES NOT CONSTITUTE AN OFFER TO SELL,
OR A SOLICITATION OF AN OFFER TO BUY, THE EXCHANGE NOTES IN ANY JURISDICTION
WHERE, OR TO ANY PERSON TO WHOM, IT IS UNLAWFUL TO MAKE SUCH OFFER OR
SOLICITATION. NEITHER THE DELIVERY OF THIS PROSPECTUS NOR ANY SALE MADE
HEREUNDER SHALL, UNDER ANY CIRCUMSTANCES, CREATE ANY IMPLICATIONS THAT THERE HAS
NOT BEEN ANY CHANGE IN THE FACTS SET FORTH IN THIS PROSPECTUS OR IN THE AFFAIRS
OF THE COMPANY SINCE THE DATE HEREOF.
 
                DISCLOSURE REGARDING FORWARD-LOOKING STATEMENTS
 
     This Prospectus includes "forward-looking statements" within the meaning of
Section 27A of the Securities Act and Section 21E of the Securities Exchange Act
of 1934, as amended (the "Exchange Act"). All statements other than statements
of historical facts included in this Prospectus, including without limitation,
statements under "Prospectus Summary," "Risk Factors" and "Management's
Discussion and Analysis of Financial Condition and Results of Operations"
regarding the planned capital expenditures, increases in oil and gas production,
the number of anticipated wells to be drilled in 1998 and thereafter, the
Company's financial position, business strategy and other plans and objectives
for future operations, are forward-looking statements. Although the Company
believes that the expectations reflected in such forward-looking statements are
reasonable, it can give no assurance that such expectations will prove to have
been correct. There are numerous uncertainties inherent in estimating quantities
of proved oil and natural gas reserves and in projecting future rates of
production and timing of development expenditures, including many factors beyond
the control of the Company. Reserve engineering is a subjective process of
estimating underground accumulations of oil and natural gas that cannot be
measured in an exact way, and the accuracy of any reserve estimate is a function
of the quality of available data and of engineering and geological
interpretation and judgment. As a result, estimates made by different engineers
often vary from one another. In addition, results of drilling, testing and
production subsequent to the date of an estimate may justify revisions of such
estimates and such revisions, if significant, would change the schedule of any
further production and development drilling. Accordingly, reserve estimates are
generally different from the quantities of oil and natural gas that are
ultimately recovered. Additional important factors that could cause actual
results to differ materially from the Company's expectations are disclosed under
"Risk Factors" and elsewhere in this Prospectus, including, without limitation,
in conjunction with the forward-looking statements included in this Prospectus.
All subsequent written and oral forward-looking statements attributable to the
Company or persons acting on its behalf are expressly qualified in their
entirety by such factors.
 
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<PAGE>   4
 
                               PROSPECTUS SUMMARY
 
     The following summary is qualified in its entirety by and should be read in
conjunction with the more detailed information and financial statements,
including the notes thereto, included elsewhere and incorporated by reference in
this Prospectus. Unless otherwise indicated, references to "Houston Exploration"
or the "Company" refer to The Houston Exploration Company and its subsidiaries
on a combined basis. Investors should carefully consider the information set
forth under "Risk Factors." Certain oil and gas industry terms used in this
Prospectus are defined in "Glossary of Oil and Gas Terms."
 
     This Prospectus contains certain forward-looking statements with respect to
the business of the Company and the industry in which it operates. These
forward-looking statements are subject to certain risks and uncertainties which
may cause actual results to differ significantly from such forward-looking
statements. See "Disclosure Regarding Forward-Looking Statements" and "Risk
Factors."
 
                                  THE COMPANY
 
     Houston Exploration is an independent natural gas and oil company engaged
in the exploration, development, exploitation and acquisition of domestic
natural gas and oil properties. The Company's offshore properties are located
primarily in the shallow waters (up to 600 feet) of the Gulf of Mexico, and its
onshore properties are located in South Texas, the Arkoma Basin, East Texas and
West Virginia. The Company has utilized its geological and geophysical expertise
to grow its reserve base through a combination of high potential exploratory
drilling in the Gulf of Mexico and lower risk, high impact exploitation and
development drilling onshore. The Company believes that the lower risk projects
and more stable production associated with its onshore properties complement its
high potential exploratory prospects in the Gulf of Mexico by balancing risk and
reducing volatility.
 
     The Company has achieved significant growth in net proved reserves,
production, revenues and EBITDA over the past five years. The Company has
increased net proved reserves at a compound annual rate of 30% from 92 Bcfe at
December 31, 1992 to 337 Bcfe at December 31, 1997. During this period, annual
production increased at a compound annual rate of 30% from 14 Bcfe in 1992 to 51
Bcfe in 1997. Average daily production during the month of December 1997 was 179
MMcfe per day. The Company's oil and gas revenues increased from $22 million in
1992 to $116 million in 1997, and its EBITDA increased from $17 million to $93
million over the same period. At December 31, 1997, Houston Exploration reported
net proved reserves of 337 Bcfe with a discounted present value of cash flows
before income taxes ("PV-10%") of $377 million.
 
     The Company believes that its primary strengths are its high quality
reserves, its substantial inventory of high potential exploration, exploitation
and development opportunities, its expertise in generating new prospects, its
geographic focus and its low-cost operating structure. Approximately 98% of the
Company's net proved reserves at December 31, 1997 were natural gas and
approximately 78% were classified as proved developed. The Company operates over
90% of its production.
 
     The geographic focus of the Company's operations in the Gulf of Mexico and
core onshore areas enables it to manage a large asset base with a relatively
small number of employees and to add and operate production at relatively low
incremental costs. The Company achieved lease operating expenses (excluding
severance taxes) of $0.28 per Mcfe of production and net general and
administrative expenses of $0.11 per Mcfe of production for the year ended
December 31, 1997. The Company believes that these expense levels are among the
lowest within its peer group.
 
BUSINESS STRATEGY
 
     The Company's strategy is to continue to increase its reserves, production
and cash flow by pursuing internally generated exploration prospects, primarily
in the Gulf of Mexico, by conducting development and exploitation drilling on
its onshore and offshore properties and by making selective opportunistic
acquisitions. Over the past five years, the Company has added 400 Bcfe of net
proved reserves through exploration, acquisitions, and exploitation and
development. During this period, the Company has produced a total of 151 Bcfe,
and total net proved reserves added due to extensions, discoveries and revisions
were approximately
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<PAGE>   5
 
168% of cumulative production. Total net proved reserves added during this
period including acquisitions were approximately 265% of cumulative production.
During 1997, the Company increased production by more than 60%, from 32 Bcfe in
1996 to 51 Bcfe in 1997. The Company focuses on the following elements in
implementing this strategy:
 
  High Potential Exploratory and Development Drilling in the Gulf of Mexico
 
     The Company plans to drill approximately 15 exploratory wells in the Gulf
of Mexico in 1998, the successful completion of any one of which could
substantially increase the Company's reserves. Over the past five years, the
Company has drilled 20 successful exploratory wells and 19 successful
development wells in the Gulf of Mexico, representing a historical success rate
of 74%. The Company believes it has assembled a four year inventory of
exploration and development drilling opportunities in the Gulf of Mexico,
principally in shallow waters. The Company holds interests in 79 lease blocks,
representing 394,093 gross (292,837 net) acres, in federal and state waters in
the Gulf of Mexico, of which 28 have current operations. The Company has a 100%
working interest in 38 of these lease blocks and a 50% or greater working
interest in 22 other lease blocks. The Company anticipates that approximately
$68 million of its $100 million 1998 capital expenditure budget (excluding
acquisitions) will be spent on offshore projects. In addition, the Company
intends to continue its participation in federal lease sales and to actively
pursue attractive farm-in opportunities as they become available. The Company's
management believes that the Gulf of Mexico area remains attractive for future
exploration and development activities due to the availability of geologic data,
remaining reserve potential and the infrastructure of gathering systems,
pipelines, platforms and providers of drilling services and equipment. Based on
1997 annual production, the Company's offshore reserves have a reserve to
production ratio of 5.4 years. During December 1997, average net production from
the Company's Gulf of Mexico properties was approximately 62 MMcfe per day.
 
  Lower Risk, High Impact Exploitation and Development Drilling Onshore
 
     The Company owns significant onshore natural gas and oil properties in
South Texas, the Arkoma Basin of Oklahoma and Arkansas, East Texas and West
Virginia, accounting for approximately 65% of its net proved reserves at
December 31, 1997. Complementing the Company's offshore properties, the
Company's onshore properties are characterized by relatively longer reserve
lives and more predictable production. Over the past five years, the Company has
drilled or participated in the drilling of 63 successful development wells and
six successful exploratory wells onshore representing a historical drilling
success rate of 76%. One example of the successful implementation of the
Company's onshore strategy is in the Charco Field in South Texas, where the
Company has increased net production from an average of 38 MMcfe per day in July
1996, immediately following its acquisition of such properties, to an average of
92 MMcfe per day in December 1997. During 1997, the Company produced 20 Bcfe,
net to the Company's interest, from the Charco Field and added 40 Bcfe in net
proved reserves. The Company has identified an extensive inventory of more than
100 potential onshore drilling locations, of which approximately 70 are located
in the Charco Field. The Company anticipates that approximately $32 million of
its $100 million 1998 capital expenditure budget (excluding acquisitions) will
be spent on onshore projects, including the drilling of approximately 25 wells.
Based on 1997 annual production, the Company's onshore reserves have a reserve
to production ratio of 7.4 years. During December 1997, average net production
from the Company's onshore properties was approximately 117 MMcfe per day.
 
  Opportunistic Acquisitions
 
     The Company's primary strategy of growing its reserves through the drillbit
is supplemented by the Company's continuing pursuit of opportunistic
acquisitions of properties with unexploited reserve potential. The Company
targets properties (i) that it can operate, (ii) that are either in the Gulf of
Mexico or onshore in existing core operating areas or in new geographic areas in
which the Company believes it can establish a substantial concentration of
properties and operations, and (iii) that provide a base for further exploration
and development. The Company has a successful track record of building its
reserves through opportunistic acquisitions onshore and in the Gulf of Mexico
and successfully exploiting those reserves. In particular, the
 
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<PAGE>   6
 
Company has drilled 25 successful wells (74% success rate) in the Charco Field
since acquiring its properties in the field in July 1996. See "-- Recent
Acquisition."
 
  High Percentage of Operated Properties
 
     The Company seeks to operate properties in which it has a significant
ownership interest. By operating these properties, the Company can manage
production performance while controlling operating expenses and the timing and
amount of capital expenditures. Properties operated by the Company account for
approximately 90% of its Gulf of Mexico production and approximately 95% of its
onshore production. The Company currently has two offshore jackup rigs and two
land rigs under long-term contracts, which allow the Company to manage the
timing of the drilling of its wells. The Company also pursues cost savings
through the use of outside contractors for much of its offshore field operations
activities. As a result of these and other factors, the Company achieved lease
operating expense (excluding severance taxes) of $0.28 per Mcfe of production
and net general and administrative expense of $0.11 per Mcfe of production for
the year ended December 31, 1997.
 
  Use of Advanced Technology for In-House Prospect Generation
 
     The Company generates virtually all of its exploration prospects utilizing
in-house geological and geophysical expertise. The Company uses advanced
technology, including 3-D seismic and in-house computer-aided exploration
technology, to reduce risks, lower costs and prioritize drilling prospects. The
Company has acquired approximately 2,400 square miles of 3-D seismic data,
including 3-D seismic surveys on 65 of its offshore lease blocks and on possible
lease and acquisition prospects, and 73,500 linear miles of offshore 2-D seismic
data. Since the acquisition of its Charco Field properties in 1996, the Company
has purchased and commenced interpretation of 3-D seismic data covering 148
square miles of the field. In 1998, the Company anticipates the acquisition of
30 square miles of 3-D seismic data on its recently acquired East Texas acreage.
The Company has 13 geologists/geophysicists with average industry experience of
approximately 28 years and 10 geophysical workstations for use in interpreting
3-D seismic data. The availability of 3-D seismic data for Gulf of Mexico
properties at reasonable costs has enabled the Company to identify exploration
and development prospects in the Company's existing inventory of properties and
to define possible lease and acquisition prospects.
 
  Geographically Focused Operations
 
     Focusing drilling activities on properties in relatively concentrated
offshore and onshore areas permits the Company to utilize its base of
geological, engineering, exploration and production experience in the regions.
The Company currently operates in five areas of geographic concentration -- the
Gulf of Mexico, South Texas, the Arkoma Basin, East Texas, and West
Virginia -- and continues to evaluate and may add additional core areas in the
future. The Company recently completed an acquisition that adds a new core area
of operations onshore in South Louisiana. See "-- Recent Acquisition." The
geographic focus of the Company's operations allows it to manage a large asset
base with a relatively small number of employees and enables the Company to add
production at relatively low incremental costs. For example, in the Charco
Field, the Company has reduced lease operating expense (excluding severance
taxes) by 50%, from $0.38 per Mcfe for the six month period beginning on July 1,
1996, when the Company acquired its Charco Field properties, and ending December
31, 1996 to $0.19 per Mcfe for the six month period ended December 31, 1997.
 
RECENT ACQUISITION
 
     On April 29, 1998, the Company completed the acquisition of natural gas and
oil properties located onshore in South Louisiana representing 41 Bcfe of net
proved reserves as of November 1, 1997 (the "Recent Acquisition"). The average
net production in December 1997 attributable to such properties was
approximately 14 MMcfe per day. The Company paid a purchase price of $53.9
million for the Recent Acquisition, subject to adjustment for production
revenues and operating expenses between November 1, 1997 and the April 29, 1998
closing date of the acquisition.
 
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<PAGE>   7
 
OWNERSHIP
 
     Houston Exploration commenced operations in January 1986 as a wholly owned
subsidiary of The Brooklyn Union Gas Company ("Brooklyn Union") and completed an
initial public offering of 7.13 million shares of common stock, par value $0.01
per share (the "Common Stock"), in September 1996. As of March 31, 1998, the
Company had 23.9 million shares of Common Stock outstanding, and the last
reported sale price on May 13, 1998 of the Company's Common Stock on the New
York Stock Exchange was $23.00. Brooklyn Union continues to indirectly own
approximately 64% of the outstanding shares of Common Stock of the Company.
Brooklyn Union distributes gas in an area of New York City with a population of
approximately four million. In September 1997, Brooklyn Union became a wholly
owned subsidiary of KeySpan Energy Corporation ("KeySpan"), which has an equity
market capitalization of $1.7 billion, based on the May 13, 1998 closing price
of $33.94 per share of its common stock on the New York Stock Exchange, and
reported revenues of $1.5 billion for the fiscal year ended September 30, 1997.
 
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<PAGE>   8
 
                       SUMMARY OF TERMS OF EXCHANGE OFFER
 
     The Exchange Offer relates to the exchange of up to $100,000,000 aggregate
principal amount of Exchange Notes for up to an equal aggregate principal amount
of Old Notes. The Exchange Notes will be obligations of the Company entitled to
the benefits of the Indenture. The form and terms of the Exchange Notes are
identical in all material respects to the form and terms of the Old Notes,
except that (i) the offering of the Exchange Notes has been registered under the
Securities Act, (ii) the Exchange Notes will not be subject to transfer
restrictions and (iii) the Exchange Notes will not be entitled to registration
or other rights under the Registration Rights Agreement including the provision
in the Registration Rights Agreement for the payment of Liquidated Damages upon
failure by the Company to consummate the Exchange Offer or the occurrence of
certain other events. See "Description of the Notes."
 
REGISTRATION RIGHTS
AGREEMENT.....................   The Old Notes were sold by the Company on March
                                 2, 1998 to the Initial Purchasers pursuant to a
                                 Purchase Agreement, dated February 25, 1998
                                 (the "Purchase Agreement"). Pursuant to the
                                 Purchase Agreement, the Company and the Initial
                                 Purchasers entered into the Registration Rights
                                 Agreement which, among other things, grants the
                                 holders of the Old Notes certain exchange and
                                 registration rights. The Exchange Offer is
                                 intended to satisfy certain obligations of the
                                 Company under the Registration Rights
                                 Agreement.
 
THE EXCHANGE OFFER............   $1,000 principal amount of Exchange Notes will
                                 be issued in exchange for each $1,000 principal
                                 amount of Old Notes validly tendered and
                                 accepted pursuant to the Exchange Offer. As of
                                 the date hereof, $100,000,000 in aggregate
                                 principal amount of Old Notes are outstanding.
                                 The Company will issue the Exchange Notes to
                                 tendering holders of Old Notes promptly
                                 following the Expiration Date. The terms of the
                                 Exchange Notes are identical in all material
                                 respects to the Old Notes except for certain
                                 transfer restrictions and registration rights
                                 relating to the Old Notes.
 
                                 No federal or state regulatory requirements
                                 must be complied with or approval obtained in
                                 connection with the Exchange Offer, other than
                                 the registration requirements under the
                                 Securities Act.
 
RESALE........................   Based on existing interpretations of the
                                 Securities Act by the staff of the SEC set
                                 forth in several no-action letters to third
                                 parties, and subject to the immediately
                                 following sentence, the Company believes that
                                 Exchange Notes issued pursuant to the Exchange
                                 Offer in exchange for Old Notes may be offered
                                 for resale, resold and otherwise transferred by
                                 a holder thereof (other than (i) a broker-
                                 dealer who purchased such Old Notes directly
                                 from the Company for resale pursuant to Rule
                                 144A or any other available exemption under the
                                 Securities Act or (ii) a person that is an
                                 "affiliate" (within the meaning of Rule 405 of
                                 the Securities Act) of the Company), without
                                 compliance with the registration and prospectus
                                 delivery provisions of the Securities Act,
                                 provided that the holder is acquiring the
                                 Exchange Notes in its ordinary course of
                                 business and is not participating, and has no
                                 arrangement or understanding with any person to
                                 participate, in the distribution of the
                                 Exchange Notes. However, any purchaser of Notes
                                 who is an affiliate of the Company or who
                                 intends to participate in the Exchange Offer
                                 for the purpose of distributing the Exchange
 
                                        7
<PAGE>   9
 
                                 Notes, or any broker-dealer who purchased the
                                 Old Notes from the Company to resell pursuant
                                 to Rule 144A or any other available exemption
                                 under the Securities Act, (i) will not be able
                                 to rely on the interpretations by the staff of
                                 the SEC set forth in the above-mentioned
                                 no-action letters, (ii) will not be able to
                                 tender its Old Notes in the Exchange Offer and
                                 (iii) must comply with the registration and
                                 prospectus delivery requirements of the
                                 Securities Act in connection with any sale or
                                 transfer of the Notes unless such sale or
                                 transfer is made pursuant to an exemption from
                                 such requirements. The Company does not intend
                                 to seek its own no-action letter and there is
                                 no assurance that the staff of the SEC would
                                 make a similar determination with respect to
                                 the Exchange Notes as it has in such no-action
                                 letters to third parties. See "The Exchange
                                 Offer -- Purpose and Effect of the Exchange
                                 Offer" and "Plan of Distribution." Each
                                 broker-dealer that receives Exchange Notes for
                                 its own account pursuant to the Exchange Offer
                                 must acknowledge that it will deliver a
                                 prospectus in connection with any resale of
                                 such Exchange Notes. The Letter of Transmittal
                                 states that by so acknowledging and by
                                 delivering a prospectus, a broker-dealer will
                                 not be deemed to admit that it is an
                                 "underwriter" within the meaning of the
                                 Securities Act. This Prospectus, as it may be
                                 amended or supplemented from time to time, may
                                 be used by a broker-dealer in connection with
                                 resales of Exchange Notes received in
                                 connection with resales of Exchange Notes
                                 received in exchange for Old Notes where such
                                 Old Notes were acquired by such broker-dealer
                                 as a result of market-making activities or
                                 other trading activities. The Company has
                                 agreed that, for a period of up to 180 days
                                 after the Expiration Date, it will make this
                                 Prospectus available to any broker-dealer for
                                 use in connection with any such resale. See
                                 "Plan of Distribution."
 
EXPIRATION DATE...............   5:00 p.m., New York City time, on June 14,
                                 1998, unless the Exchange Offer is extended, in
                                 which case the term "Expiration Date" means the
                                 latest date and time to which the Exchange
                                 Offer is extended. See "The Exchange
                                 Offer -- Expiration Date; Extensions;
                                 Amendments."
 
ACCRUED INTEREST ON THE
  EXCHANGE NOTES AND THE
  OLD NOTES...................   The Exchange Notes will bear interest at a rate
                                 of 8 5/8% per annum, payable semiannually on
                                 January 1 and July 1 of each year, commencing
                                 July 1, 1998. Holders of Exchange Notes of
                                 record on June 15, 1998 will receive on July 1,
                                 1998 an interest payment in an amount equal to
                                 (x) the accrued interest on such Exchange Notes
                                 from the date of issuance thereof to July 1,
                                 1998, plus (y) the accrued interest on the
                                 previously held Old Notes from the date of
                                 issuance of such Old Notes (March 2, 1998) to
                                 the date of exchange thereof. Interest will not
                                 be paid on Old Notes that are accepted for
                                 exchange. The Notes mature on January 1, 2008.
 
CONDITIONS TO THE EXCHANGE
OFFER.........................   The Company may terminate the Exchange Offer if
                                 it determines that its ability to proceed with
                                 the Exchange Offer could be materially impaired
                                 due to the occurrence of certain conditions.
 
                                        8
<PAGE>   10
 
                                 The Company does not expect any of such
                                 conditions to occur, although there can be no
                                 assurance that such conditions will not occur.
                                 Holders of Old Notes will have certain rights
                                 under the Registration Rights Agreement should
                                 the Company fail to consummate the Exchange
                                 Offer. See "The Exchange Offer -- Conditions to
                                 the Exchange Offer."
 
PROCEDURES FOR TENDERING OLD
NOTES.........................   Each holder of Old Notes wishing to accept the
                                 Exchange Offer must complete, sign and date the
                                 Letter of Transmittal, or a facsimile thereof,
                                 in accordance with the instructions contained
                                 herein and therein, and mail or otherwise
                                 deliver such Letter of Transmittal, or such
                                 facsimile, together with the Old Notes to be
                                 exchanged and any other required documentation,
                                 to The Bank of New York, as Exchange Agent, at
                                 the address set forth herein and therein or
                                 effect a tender of Old Notes pursuant to the
                                 procedures for book-entry transfer as provided
                                 for herein and therein. By executing the Letter
                                 of Transmittal, each holder will represent to
                                 the Company that, among other things, the
                                 Exchange Notes acquired pursuant to the
                                 Exchange Offer are being acquired in the
                                 ordinary course of business of the person
                                 receiving such Exchange Notes, whether or not
                                 such person is the holder, that neither the
                                 holder nor any such other person has any
                                 arrangement or understanding with any person to
                                 participate in the distribution of such
                                 Exchange Notes and that neither the holder nor
                                 any such other person is an "affiliate," as
                                 defined in Rule 405 under the Securities Act,
                                 of the Company. See "The Exchange
                                 Offer -- Procedures for Tendering."
 
                                 Following consummation of the Exchange Offer,
                                 holders of Old Notes not tendered as a general
                                 matter will not have any further registration
                                 rights, and the Old Notes will continue to be
                                 subject to certain restrictions on transfer.
                                 Accordingly, the liquidity of the market for
                                 the Old Notes could be adversely affected. See
                                 "Risk Factors -- Absence of Public Market for
                                 the Notes and "-- Consequences of Exchange and
                                 Failure to Exchange" and "The Exchange
                                 Offer -- Consequences of Failure to Exchange."
 
SPECIAL PROCEDURES FOR
BENEFICIAL OWNERS.............   Any beneficial owner whose Old Notes are
                                 registered in the name of a broker, dealer,
                                 commercial bank, trust company or other nominee
                                 and who wishes to tender in the Exchange Offer
                                 should contact such registered holder promptly
                                 and instruct such registered holder to tender
                                 on his behalf. If such beneficial owner wishes
                                 to tender on his own behalf, such beneficial
                                 owner must, prior to completing and executing
                                 the Letter of Transmittal and delivering his
                                 Old Notes, either (a) make appropriate
                                 arrangements to register ownership of the Old
                                 Notes in such holder's name or (b) obtain a
                                 properly completed bond power from the
                                 registered holder or endorsed certificates
                                 representing the Old Notes to be tendered. The
                                 transfer of record ownership may take
                                 considerable time, and completion of such
                                 transfer prior to the Expiration Date may not
                                 be possible. See "The Exchange
                                 Offer -- Procedures for Tendering."
 
                                        9
<PAGE>   11
 
GUARANTEED DELIVERY
PROCEDURES....................   Holders of Old Notes who wish to tender their
                                 Old Notes and whose Old Notes are not
                                 immediately available, or who cannot deliver
                                 their Old Notes (or complete the procedure for
                                 book-entry transfer) and deliver a properly
                                 completed Letter of Transmittal and any other
                                 documents required by the Letter of Transmittal
                                 to the Exchange Agent prior to the Expiration
                                 Date may tender their Old Notes according to
                                 the guaranteed delivery procedures set forth in
                                 "The Exchange Offer -- Guaranteed Delivery
                                 Procedures."
 
WITHDRAWAL RIGHTS.............   Tenders of Old Notes may be withdrawn at any
                                 time prior to the Expiration Date by furnishing
                                 a written or facsimile transmission notice of
                                 withdrawal to the Exchange Agent containing the
                                 information set forth in "The Exchange
                                 Offer -- Withdrawal of Tenders."
 
ACCEPTANCE OF OLD NOTES AND
DELIVERY OF EXCHANGE NOTES....   Subject to certain conditions (as summarized
                                 above in "Conditions to the Exchange Offer" and
                                 described more fully in "The Exchange
                                 Offer -- Conditions to the Exchange Offer"),
                                 the Company will accept for exchange any and
                                 all Old Notes that are properly tendered in the
                                 Exchange Offer prior to the Expiration Date.
                                 See "The Exchange Offer -- Procedures for
                                 Tendering." The Exchange Notes issued pursuant
                                 to the Exchange Offer will be delivered
                                 promptly following the Expiration Date.
 
EXCHANGE AGENT................   The Bank of New York, the Trustee under the
                                 Indenture, is serving as the Exchange Agent
                                 (the "Exchange Agent") in connection with the
                                 Exchange Offer. The mailing address of the
                                 Exchange Agent is The Bank of New York, 101
                                 Barclay Street, 7E, New York, New York 10286,
                                 Attention: Marcia Brown. The overnight courier
                                 and hand delivery address for the Exchange
                                 Agent is The Bank of New York, Tender and
                                 Exchange Department, 101 Barclay Street,
                                 Corporate Trust Services Window, Ground Level,
                                 New York, New York 10286, Attention: Marcia
                                 Brown. For assistance and requests for
                                 additional copies of the Prospectus, the Letter
                                 of Transmittal or the Notice of Guaranteed
                                 Delivery, the telephone number for the Exchange
                                 Agent is (212) 815-3428, and the facsimile
                                 number for the Exchange Agent is (212) 815-6339
                                 (Eligible Institutions only). All
                                 communications should be directed to the
                                 attention of Marcia Brown.
 
EFFECT ON HOLDERS OF OLD
NOTES.........................   Holders of Old Notes who do not tender their
                                 Old Notes in the Exchange Offer will continue
                                 to hold their Old Notes and will be entitled to
                                 all the rights and limitations applicable
                                 thereto under the Indenture. All untendered,
                                 and tendered but unaccepted, Old Notes will
                                 continue to be subject to the restrictions on
                                 transfer provided for in the Old Notes and the
                                 Indenture. To the extent that Old Notes are
                                 tendered and accepted in the Exchange Offer,
                                 the trading market, if any, for the Old Notes
                                 could be adversely affected. See "Risk
                                 Factors -- Consequences of Exchange and Failure
                                 to Exchange."
 
     See "The Exchange Offer" for more detailed information concerning the terms
of the Exchange Offer.
 
                                       10
<PAGE>   12
 
                       SUMMARY OF TERMS OF EXCHANGE NOTES
 
     All capitalized terms used in this Prospectus with respect to the Notes and
not otherwise defined herein have the meanings set forth under "Description of
the Notes."
 
SECURITIES OFFERED............   $100,000,000 aggregate principal amount of
                                 8 5/8% Senior Subordinated Notes due 2008,
                                 Series B.
 
MATURITY DATE.................   January 1, 2008.
 
INTEREST RATE.................   Interest on the Exchange Notes will accrue at a
                                 rate of 8 5/8% per annum and will be payable
                                 semi-annually in arrears on each January 1 and
                                 July 1, commencing July 1, 1998.
 
MANDATORY REDEMPTION..........   The Company is not required to make mandatory
                                 redemption or sinking fund payments with
                                 respect to the Exchange Notes except as set
                                 forth under "Description of the
                                 Notes -- Repurchase at the Option of Holders."
 
OPTIONAL REDEMPTION...........   On or after January 1, 2003, the Company may
                                 redeem the Exchange Notes, at the redemption
                                 prices set forth herein, plus accrued and
                                 unpaid interest to the date of redemption.
                                 Notwithstanding the foregoing, at any time
                                 prior to January 1, 2001, the Company may
                                 redeem up to 35% of the original aggregate
                                 principal amount of the Exchange Notes with the
                                 net proceeds of an Equity Offering at a
                                 redemption price equal to 108.625% of the
                                 principal amount thereof, plus accrued and
                                 unpaid interest to the date of redemption;
                                 provided that at least 65% of the original
                                 aggregate principal amount of the Exchange
                                 Notes remains outstanding after such
                                 redemption. See "Description of the Notes --
                                 Optional Redemption."
 
RANKING.......................   The Exchange Notes will be general unsecured
                                 obligations of the Company, will rank
                                 subordinate in right of payment to all existing
                                 and future Senior Debt of the Company and will
                                 rank senior or pari passu in right of payment
                                 to all existing and future subordinated
                                 indebtedness of the Company. The Exchange Notes
                                 will be effectively subordinated to all
                                 liabilities, if any, of any subsidiaries of the
                                 Company. As of December 31, 1997, on a pro
                                 forma basis, the Company had $15.4 million of
                                 Senior Debt outstanding, $42.4 million of trade
                                 payables and other accrued liabilities, and no
                                 other senior subordinated indebtedness other
                                 than the Exchange Notes. On a pro forma basis,
                                 the Company would have had the capacity to
                                 borrow an additional $119.6 million of Senior
                                 Debt under the Credit Facility. See "Risk
                                 Factors -- Subordination of the Notes."
 
CHANGE OF CONTROL.............   Upon a Change of Control, each holder will have
                                 the right to require the Company to repurchase
                                 such holder's Exchange Notes at a price equal
                                 to 101% of the principal amount thereof plus
                                 accrued and unpaid interest to the date of
                                 repurchase. See "Description of the
                                 Notes -- Repurchase at the Option of Holders."
                                 There can be no assurance that the Company will
                                 have sufficient funds to repurchase the
                                 Exchange Notes in the event of a Change of
                                 Control.
 
                                       11
<PAGE>   13
 
CERTAIN COVENANTS.............   The Indenture pursuant to which the Exchange
                                 Notes will be issued contains certain covenants
                                 which, among other things, limit the ability of
                                 the Company and its Restricted Subsidiaries to:
                                 (i) incur additional indebtedness and issue
                                 preferred stock; (ii) repay certain other
                                 indebtedness; (iii) pay dividends or make
                                 certain other distributions; (iv) repurchase
                                 equity interests or make certain investments;
                                 (v) consummate certain asset sales; (vi) enter
                                 into certain transactions with affiliates;
                                 (vii) incur liens; (viii) merge or consolidate
                                 with any other person; (ix) sell, assign,
                                 transfer, lease, convey or otherwise dispose of
                                 all or substantially all of the assets of the
                                 Company and its Restricted Subsidiaries; (x)
                                 enter into agreements that restrict the ability
                                 of Restricted Subsidiaries to make certain
                                 distributions or payments or (xi) enter into
                                 guarantees of Indebtedness of the Company. In
                                 addition, under certain circumstances, the
                                 Company will be required to make an offer to
                                 purchase the Exchange Notes at a price equal to
                                 100% of the principal amount thereof, plus
                                 accrued and unpaid interest to the date of
                                 purchase, with the proceeds from certain asset
                                 sales. See "Description of the Notes -- Certain
                                 Covenants" and "-- Repurchase at the Option of
                                 Holders -- Asset Sales."
 
TRANSFER RESTRICTIONS.........   For a description of restrictions on transfer
                                 of the Exchange Notes, see "The Exchange
                                 Offer -- Purpose and Effect of the Exchange
                                 Offer."
 
                                  RISK FACTORS
 
     See "Risk Factors," beginning on page 16 hereof, for a discussion of
certain factors that should be considered in evaluating an investment in the
Exchange Notes.
 
                                       12
<PAGE>   14
 
                        SUMMARY COMBINED FINANCIAL DATA
 
     The summary combined financial data set forth below with respect to the
Company's combined statements of operations for each of the three years in the
period ended December 31, 1997 and with respect to the Company's combined
balance sheets as of December 31, 1997 are derived from the financial statements
of the Company that have been audited by Arthur Andersen LLP, independent public
accountants. The summary combined financial data should be read in conjunction
with the "Management's Discussion and Analysis of Financial Condition and
Results of Operations" and the Company's Financial Statements and Notes thereto
included elsewhere and incorporated by reference in this Prospectus.
 
<TABLE>
<CAPTION>
                                                                YEARS ENDED DECEMBER 31,
                                                              -----------------------------
                                                               1995       1996       1997
                                                              -------   --------   --------
                                                              (IN THOUSANDS, EXCEPT RATIOS)
<S>                                                           <C>       <C>        <C>
COMBINED STATEMENT OF OPERATIONS DATA:
Revenues:
  Natural gas and oil revenues..............................  $39,431   $ 64,864   $116,349
  Other.....................................................    1,778      1,040      1,297
                                                              -------   --------   --------
          Total revenues....................................   41,209     65,904    117,646
Expenses:
  Lease operating...........................................    5,005     10,800     14,146
  Severance tax.............................................      463      1,401      4,233
  Depreciation, depletion and amortization..................   21,969     33,732     59,081
  General and administrative, net...........................    3,486      6,249      5,825
  Nonrecurring charge(1)....................................   12,000         --         --
                                                              -------   --------   --------
          Total operating expenses..........................   42,923     52,182     83,285
Income (loss) from operations...............................   (1,714)    13,722     34,361
Interest expense, net.......................................    2,398      2,875        938
Income (loss) before income taxes...........................   (4,112)    10,847     33,423
Income tax provision (benefit)..............................   (3,809)     2,205     10,173
                                                              -------   --------   --------
Net income (loss)...........................................  $  (303)  $  8,642   $ 23,250
                                                              =======   ========   ========
OTHER DATA:
EBITDA(2)...................................................  $32,255   $ 47,454   $ 93,442
Capital expenditures(3).....................................   70,249    154,125    145,055
PRO FORMA DATA:(4)
Cash interest expense(5)....................................                       $  9,792
Ratio of EBITDA to cash interest expense....................                            9.5x
Ratio of net debt to EBITDA(6)..............................                            1.2x
</TABLE>
 
<TABLE>
<CAPTION>
                                                               AS OF DECEMBER 31, 1997
                                                              -------------------------
                                                               ACTUAL    AS ADJUSTED(7)
                                                              --------   --------------
                                                                   (IN THOUSANDS)
<S>                                                           <C>        <C>
BALANCE SHEET DATA:
Cash and cash equivalents...................................  $  4,745      $  4,245
Working capital (deficit)(8)................................    (5,401)       (5,901)
Property, plant and equipment, net..........................   443,738       443,738
Total assets................................................   491,391       493,766
Total long-term debt........................................   113,000       115,375(9)
Stockholders' equity........................................   256,187       256,187
</TABLE>
 
Footnotes on next page
 
                                       13
<PAGE>   15
 
- ---------------
 
(1) Represents a nonrecurring non-cash charge incurred in connection with the
    reorganization effective in February 1996. See Note 11 to the Company's
    Combined Financial Statements.
 
(2) EBITDA is defined as income (loss) from operations (before nonrecurring
    charges) plus depreciation, depletion and amortization. EBITDA should not be
    considered as an alternative to income (loss) from operations or net income
    (loss), as determined in accordance with generally accepted accounting
    principles, as a measure of the Company's operating performance or to net
    cash provided by operating, investing and financing activities, as
    determined in accordance with generally accepted accounting principles, as a
    measure of the Company's ability to meet cash needs. The Company believes
    that EBITDA is a measure commonly reported and widely used by investors and
    other interested parties as a measure of a company's operating performance
    and debt servicing ability because it assists in comparing performance on a
    consistent basis without regard to depreciation, depletion and amortization,
    which can vary significantly depending upon accounting methods (particularly
    when acquisitions are involved) or nonoperating factors (such as historical
    cost). Accordingly, this information has been disclosed herein to permit a
    more complete comparative analysis of the Company's operating performance
    relative to other companies and of the Company's debt servicing ability.
    However, EBITDA may not be comparable in all instances to other similar
    types of measures used.
 
(3) Capital expenditures reflected in the table consist of cash used for
    investments in property and equipment, and do not reflect non-cash capital
    expenditures in the year ended December 31, 1996 of $22.9 million reflecting
    the issuance of shares of the Company's Common Stock in consideration for
    its acquisition of natural gas and oil properties. Including the $22.9
    million in non-cash capital expenditures, the Company's capital expenditures
    for 1996 would have been approximately $177.0 million.
 
(4) Gives pro forma effect to the sale of the Old Notes and the application of
    the net proceeds therefrom as if it had occurred on January 1, 1997. Does
    not give effect to the Recent Acquisition.
 
(5) Pro forma cash interest is defined as (i) gross interest expense of $6.8
    million less (ii) amortization of debt issue costs of $0.3 million less
    (iii) interest on debt refinanced of $5.3 million plus (iv) interest on $100
    million of 8 5/8% Senior Subordinated Notes of $8.6 million.
 
(6) Net debt is defined as total debt less cash and cash equivalents at December
31, 1997.
 
(7) As adjusted to give effect to the sale of the Old Notes and the application
    of the net proceeds therefrom as if it had occurred on December 31, 1997;
    does not reflect any borrowings under the Credit Facility to fund the
    purchase price of the Recent Acquisition.
 
(8) Includes accrual for the minimum deferred purchase price of $8.8 million
    with respect to the Company's 1996 acquisition of certain offshore
    properties from Smith Offshore Exploration Company. See Note 12 to the
    Company's Combined Financial Statements. The Company paid the deferred
    purchase price in the first quarter of 1998 by delivering 520,777 shares of
    Common Stock with an aggregate value (determined by reference to a 20
    trading day average price of the Common Stock) of $8.8 million.
 
(9) The Company used the net proceeds from the sale of the Old Notes to repay
    indebtedness outstanding under the Credit Facility. As amended, the Credit
    Facility has a borrowing base of $135 million.
 
                                       14
<PAGE>   16
 
                             SUMMARY OPERATING DATA
 
<TABLE>
<CAPTION>
                                                                YEARS ENDED DECEMBER 31,
                                                              -----------------------------
                                                               1995       1996       1997
                                                              -------    -------    -------
<S>                                                           <C>        <C>        <C>
Production:
  Natural gas (MMcf)........................................   21,077     31,215     50,310
  Oil (MBbls)...............................................      100        118        171
  Total (MMcfe).............................................   21,677     31,923     51,336
Average sales prices:
  Natural Gas (per Mcf)(1)..................................  $  1.79    $  2.00    $  2.25
  Oil (per Bbl).............................................    16.54      21.53      18.33
Expenses (per Mcfe):
  Lease operating...........................................  $  0.23    $  0.34    $  0.28
  Severance tax.............................................     0.02       0.04       0.08
  Depreciation, depletion and amortization..................     1.01       1.06       1.15
  General and administrative, net...........................     0.16       0.20       0.11
</TABLE>
 
- ---------------
 
(1) Reflects the effects of hedging. Absent the effects of hedging, average
    realized natural gas prices would have been $1.53, $2.35 and $2.45 per Mcf
    for the years ended December 31, 1995, 1996 and 1997, respectively. See
    "Risk Factors -- Hedging Risks," "Management's Discussion and Analysis of
    Financial Condition and Results of Operations -- General" and
    "Business -- Marketing and Customers."
 
                    SUMMARY NATURAL GAS AND OIL RESERVE DATA
 
     The following table summarizes the estimates of the Company's historical
net proved natural gas and oil reserves as of the dates indicated and the
present value attributable to these reserves at such dates. The reserve and
present value data as of December 31, 1997 have been prepared by Netherland,
Sewell & Associates, Inc. ("NSA"), and Miller and Lents, Ltd. ("Miller and
Lents"), independent petroleum engineering consultants. The reserve data and
present values as of December 31, 1996 were prepared by NSA, Miller and Lents
and Ryder Scott Company and as of December 31, 1995, by NSA, Miller and Lents,
Ryder Scott Company and Huddleston & Co., Inc. For additional information
relating to the Company's natural gas and oil reserves, see "Business -- Natural
Gas and Oil Reserves" and Note 13 of the Notes to the Combined Financial
Statements of the Company included elsewhere and incorporated by reference in
this Prospectus. The reserves stated in the table below do not include any
reserves acquired in the Recent Acquisition.
 
<TABLE>
<CAPTION>
                                                                     AS OF DECEMBER 31,
                                                              --------------------------------
                                                                1995        1996        1997
                                                              --------    --------    --------
                                                              (IN THOUSANDS, EXCEPT OPERATING
                                                                           DATA)
<S>                                                           <C>         <C>         <C>
Net Proved Reserves:
  Natural gas (MMcf)........................................   195,946     320,474     330,601
  Oil (MBbls)...............................................       889       1,131       1,077
  Total (MMcfe).............................................   201,280     327,260     337,063
Present value of future net revenues before income
  taxes(1)..................................................  $206,574    $577,000    $377,065
Standardized measure of discounted future net cash
  flows(2)..................................................  $171,459    $452,582    $315,380
</TABLE>
 
- ---------------
 
(1) The present value of future net revenues attributable to the Company's
    reserves was prepared using prices in effect as of the end of the respective
    periods presented, discounted at 10% per annum on a pre-tax basis. Such
    amounts reflect the effects of the Company's hedging contracts and do not
    reflect the effects of Section 29 tax credits which were monetized in 1997.
    Average prices per Mcf of natural gas used in making such present value
    determinations as of December 31, 1995, 1996 and 1997 were $2.06, $3.41 and
    $2.31, respectively. Average prices per Bbl of oil used in making such
    present value determinations as of December 31, 1995, 1996 and 1997 were
    $17.29, $22.94 and $17.23, respectively.
 
(2) The standardized measure of discounted future net cash flows represents the
    present value of future net revenues after income tax discounted at 10%.
    Such amounts reflect the effects of the Company's hedging contracts.
 
                                       15
<PAGE>   17
 
                                  RISK FACTORS
 
     Holders of Old Notes should carefully consider the information set forth
below, as well as other information appearing in this Prospectus, before
tendering any Old Notes for exchange into Exchange Notes. Certain matters set
forth below also apply to the Old Notes and will continue to apply to any Old
Notes remaining outstanding after the Exchange Offer.
 
VOLATILITY OF NATURAL GAS AND OIL PRICES
 
     Revenues generated from the Company's operations are highly dependent upon
the price of, and demand for, natural gas and oil. Historically, the markets for
natural gas and oil have been volatile, and such markets are likely to continue
to be volatile in the future. Prices for natural gas and oil are subject to wide
fluctuation in response to relatively minor changes in the supply of and demand
for natural gas and oil, market uncertainty and a variety of additional factors
that are beyond the control of the Company. These factors include the level of
consumer product demand, weather conditions, domestic and foreign governmental
regulations, the price and availability of alternative fuels, political
conditions in the Middle East, the foreign supply of natural gas and oil, the
price of foreign imports and overall domestic and global economic conditions. It
is impossible to predict future natural gas and oil price movements with any
certainty. Declines in natural gas and oil prices also may reduce the amount of
natural gas and oil that the Company can produce economically.
 
     In order to reduce its exposure to short-term fluctuations in the price of
natural gas, the Company enters into hedging arrangements from time to time. The
Company's hedging arrangements apply to only a portion of its production and
provide only partial price protection against declines in natural gas prices. In
addition, the Company's hedging arrangements limit the benefit to the Company of
increases in the price of natural gas. See "-- Hedging Risks," "Management's
Discussion and Analysis of Financial Condition and Results of
Operations -- General" and "Business -- Marketing and Customers."
 
     The Company uses the full cost method of accounting for its investment in
natural gas and oil properties. Under the full cost method of accounting, all
costs of acquisition, exploration and development of natural gas and oil
reserves are capitalized into a "full cost pool" as incurred, and properties in
the pool are depleted and charged to operations using the unit-of-production
method based on the ratio of current production to total proved natural gas and
oil reserves. To the extent that such capitalized costs (net of accumulated
depreciation, depletion and amortization) less deferred taxes exceed the present
value (using a 10% discount rate) of estimated future net cash flows from proved
natural gas and oil reserves and the lower of cost or fair value of unproved
properties after income tax effects, such excess costs are charged to
operations. If a writedown is required, it would result in a charge to earnings
but would not have an impact on cash flows from operating activities. Once
incurred, a writedown of oil and gas properties is not reversible at a later
date even if oil and gas prices increase.
 
     As of December 31, 1997, the Company estimates, using prices in effect as
of such date, that the ceiling limitation imposed under full cost accounting
rules on total capitalized natural gas and oil property costs exceeded actual
capitalized costs. Natural gas prices have fluctuated substantially from prices
used in reserve valuations for the year ended December 31, 1997. Depending upon
natural gas prices and the results of the Company's drilling programs, the
Company may be required to write down the carrying value of its natural gas and
oil properties.
 
UNCERTAINTY OF RESERVE INFORMATION AND FUTURE NET REVENUE ESTIMATES
 
     There are numerous uncertainties inherent in estimating natural gas and oil
reserves and their estimated values, including many factors beyond the control
of the producer. The reserve data set forth in this Prospectus represents only
estimates. Reservoir engineering is a subjective process of estimating
underground accumulations of natural gas and oil that cannot be measured in an
exact manner. Estimates of economically recoverable natural gas and oil reserves
and of future net cash flows necessarily depend upon a number of variable
factors and assumptions, such as historical production from the area compared
with production from other producing areas, the assumed effects of regulations
by governmental agencies and assumptions concerning future natural gas and oil
prices, future operating costs, severance and excise taxes, development
                                       16
<PAGE>   18
 
costs and workover and remedial costs, all of which may in fact vary
considerably from actual results. For these reasons, estimates of the
economically recoverable quantities of natural gas and oil attributable to any
particular group of properties, classifications of such reserves based on risk
of recovery, and estimates of the future net cash flows expected therefrom
prepared by different engineers or by the same engineers but at different times
may vary substantially and such reserve estimates may be subject to downward or
upward adjustment based upon such factors. Actual production, revenues and
expenditures with respect to the Company's reserves will likely vary from
estimates, and such variances may be material. See "Business -- Natural Gas and
Oil Reserves."
 
RESERVE REPLACEMENT RISK
 
     In general, the volume of production from natural gas and oil properties
declines as reserves are depleted. The rate of decline depends on reservoir
characteristics, and varies from the steep decline rate characteristic of Gulf
of Mexico reservoirs, where the Company has a significant portion of its
production, initial steep decline followed by relatively slower decline in South
Texas to the relatively slow decline rate characteristic of the longer-lived
fields in the Arkoma Basin, East Texas and West Virginia. The proved reserves of
the Company will decline as reserves are produced, except to the extent the
Company acquires properties containing proved reserves or conducts successful
exploration and development activities, or both. The Company's future natural
gas and oil production is, therefore, highly dependent upon its level of success
in finding or acquiring additional reserves. The business of exploring for,
developing or acquiring reserves is capital intensive. To the extent cash flow
from operations is reduced and external sources of capital become limited or
unavailable, the Company's ability to make the necessary capital investment to
maintain or expand its asset base of natural gas and oil reserves would be
impaired. In addition, there can be no assurance that the Company's future
exploration, development and acquisition activities will result in additional
proved reserves or that the Company will be able to drill productive wells at
acceptable costs.
 
DRILLING RISKS
 
     Drilling involves numerous risks, including the risk that no commercially
productive natural gas or oil reservoirs will be encountered. The cost of
drilling, completing and operating wells is often uncertain, and drilling
operations may be curtailed, delayed or canceled as a result of a variety of
factors, including unexpected drilling conditions, pressure or irregularities in
formations, equipment failures or accidents, adverse weather conditions and
shortages or delays in the delivery of equipment. The Company's future drilling
activities may not be successful and, if unsuccessful, such failure will have an
adverse effect on the Company's future results of operations and financial
condition.
 
OPERATING RISKS OF NATURAL GAS AND OIL OPERATIONS
 
     The natural gas and oil business involves certain operating hazards such as
well blowouts, collapse or failure of wellbore or tubulars, explosions,
uncontrollable flows of oil, natural gas or well fluids, fires, formations with
abnormal pressures, pollution, releases of toxic gas and other environmental
hazards and risks, any of which could result in substantial losses to the
Company. The Company's offshore operations also are subject to the additional
hazards of marine operations, such as severe weather, capsizing and collision.
The availability of a ready market for the Company's natural gas and oil
production also depends on the proximity of reserves to, and the capacity of,
natural gas and oil gathering systems, pipelines and trucking or terminal
facilities. In addition, the Company may be liable for environmental damages
caused by previous owners of property purchased or leased by the Company. As a
result, substantial liabilities to third parties or governmental entities may be
incurred, the payment of which could reduce or eliminate the funds available for
exploration, development or acquisitions or result in the loss of the Company's
properties. In accordance with customary industry practices, the Company
maintains insurance against some, but not all, of such risks and losses. The
Company does not carry business interruption insurance. The occurrence of such
an event not fully covered by insurance could have a material adverse effect on
the financial condition and results of operations of the Company.
 
                                       17
<PAGE>   19
 
     Most of the Company's natural gas is transported through gas gathering
systems and gas pipelines which are not owned by the Company. Transportation
space on such gathering systems and pipelines is occasionally limited and at
times unavailable due to repairs or improvements being made to such facilities
or due to such space being utilized by other gas shippers with priority
transportation agreements. While the Company's ability to market its natural gas
has been subject to limitations or delays only on a very infrequent basis, if
transportation space is restricted or is unavailable, the Company's cash flow
from the affected properties could be adversely affected.
 
ACQUISITION RISKS
 
     The successful acquisition of producing properties requires an assessment
of recoverable reserves, future oil and gas prices, operating costs, potential
environmental and other liabilities and other factors. The accuracy of such
assessments is inherently uncertain. In connection with such as assessment, the
Company performs a review of the subject properties that it believes to be
generally consistent with industry practice, which generally includes on-site
inspections and the review of reports filed with the Minerals Management Service
for environmental compliance. Such a review, however, will not reveal all
existing or potential problems nor will it permit a buyer to become sufficiently
familiar with the properties to fully assess their deficiencies and
capabilities. Inspections may not always be performed on every platform or well,
and structural or environmental problems are not necessarily observable even
when an inspection is undertaken. As a result of the foregoing factors, the
Company may suffer the loss of one or more acquired properties due to title
deficiencies or may be required to make significant expenditures to cure
environmental contamination with respect to acquired properties. Even when
problems are identified, the seller may be unwilling or unable to provide
effective contractual protection against all or part of such problems. The
Company is generally not entitled to contractual indemnification for
environmental liabilities and acquires structures on a property on an "as is"
basis.
 
SUBSTANTIAL CAPITAL REQUIREMENTS
 
     The Company's business is capital intensive and to maintain its base of
proved oil and gas reserves, a significant amount of cash flow from operations
must be invested in property acquisitions, development or exploration
activities. The Company makes, and will continue to make, substantial capital
expenditures for the exploration, development, acquisition and production of
natural gas and oil reserves. Historically, the Company has financed these
expenditures primarily with cash generated by operations, proceeds from bank
borrowings and the Company's initial public offering ("IPO") and, prior to the
Company's IPO, capital contributions by Brooklyn Union. The Company plans to
incur capital expenditures (excluding acquisitions) of approximately $100
million in 1998. Management believes that the Company will have sufficient cash
provided by operating activities and borrowings under the Credit Facility to
fund planned capital expenditures in 1998. If revenues or the Company's
borrowing base decrease as a result of lower natural gas and oil prices,
operating difficulties or declines in reserves, the Company may have limited
ability to expend the capital necessary to undertake or complete future drilling
programs or acquisition opportunities. Without such investment, the Company's
oil and gas reserves would decline. There can be no assurance that additional
debt or equity financing or cash generated by operations will be available to
meet these requirements. See "Management's Discussion and Analysis of Financial
Condition and Results of Operations -- Liquidity and Capital Resources."
 
HEDGING RISKS
 
     From time to time, the Company enters into hedging arrangements relating to
a portion of its natural gas production. These hedges have in the past involved
fixed arrangements and other arrangements at a variety of fixed prices and with
a variety of other provisions including price floors and ceilings. The Company
may in the future enter into natural gas futures contracts, options, collars and
swaps. The Company's hedging activities, while intended to reduce the Company's
sensitivity to changes in market prices of natural gas, are subject to a number
of risks including instances in which (i) production is less than expected, (ii)
there is a widening of price differentials between delivery points required by
fixed price delivery contracts to the extent they differ
 
                                       18
<PAGE>   20
 
from those on the Company's production or (iii) the Company's counterparties to
its futures contract will be unable to meet the financial terms of the
transaction. While the use of hedging arrangements limits the risk of declines
in natural gas prices, it may limit the benefit to the Company of increases in
the price of natural gas. See "Management's Discussion and Analysis of Financial
Condition and Results of Operations -- Liquidity and Capital Resources."
 
EFFECTS OF LEVERAGE
 
     The Company's senior credit facility (the "Credit Facility") provides for a
commitment of $150 million and has a current borrowing base of $135 million. The
Company had availability of approximately $15.4 million under the Credit
Facility at December 31, 1997. See "Management's Discussion and Analysis of
Financial Condition and Results of Operations -- Liquidity and Capital
Resources."
 
     On a pro forma basis giving effect to the sale of the Old Notes, the
Company's outstanding indebtedness at December 31, 1997 would have been $115.4
million, without giving effect to borrowings that would be required to fund the
Pending Acquisition, if completed. The Company's level of indebtedness has
several important effects on its operations, including (i) a substantial portion
of the Company's cash flow from operations must be dedicated to the payment of
interest on its indebtedness and will not be available for other purposes, (ii)
the covenants contained in the Credit Facility and the Indenture require the
Company to meet certain financial tests, and other restrictions limit its
ability to borrow additional funds or to dispose of assets and may affect the
Company's flexibility in planning for, and reacting to, changes in business
conditions and (iii) the Company's ability to obtain additional financing in the
future for working capital, capital expenditures, acquisitions, general
corporate purposes or other purposes may be impaired. Moreover, future
acquisition or development activities may require the Company to alter its
capitalization significantly. These changes in capitalization may significantly
alter the leverage of the Company. The Company's ability to meet its debt
service obligations and to reduce its total indebtedness will be dependent upon
the Company's future performance, which will be subject to general economic
conditions and to financial, business and other factors affecting the operations
of the Company, many of which are beyond its control. There can be no assurance
that the Company's future performance will not be adversely affected by such
economic conditions and financial, business and other factors. See "Management's
Discussion and Analysis of Financial Condition and Results of
Operations -- Liquidity and Capital Resources."
 
SUBORDINATION OF THE NOTES
 
     The Notes are subordinated in right of payment to all existing and future
Senior Debt of the Company, which includes all indebtedness under the Credit
Facility. After giving pro forma effect to the sale of the Old Notes and the
application of the net proceeds therefrom, the Company would have had $15.4
million of Senior Debt outstanding and would have had up to $119.6 million of
additional borrowing capacity available under the Credit Facility which, if
borrowed, would be included as Senior Debt. In the event of a liquidation,
dissolution, reorganization, bankruptcy or any similar proceeding regarding the
Company, the assets of the Company will be available to pay obligations on the
Notes only after Senior Debt of the Company has been paid in full. Additional
Senior Debt may be incurred by the Company from time to time, subject to certain
restrictions imposed by the Indenture and the Credit Facility. Accordingly,
there may not be sufficient funds remaining to pay amounts due on all or any of
the Notes. See "Description of the Notes -- Ranking and Subordination."
 
     In addition to being subordinated to all existing and future Senior Debt of
the Company, the Notes will not be secured by any of the Company's or its
Subsidiaries' assets, as the case may be.
 
PAYMENT UPON A CHANGE OF CONTROL
 
     Upon the occurrence of a Change of Control, each holder of the Notes may
require the Company to purchase all or a portion of such holder's Notes at 101%
of the principal amount of the Notes, together with accrued and unpaid interest
and Liquidated Damages, if any, to the date of purchase. The occurrence of a
Change of Control may result in a default under the Credit Facility which
prohibits the purchase of the Notes
 
                                       19
<PAGE>   21
 
by the Company unless and until such time as the Company's indebtedness under
the Credit Facility is repaid. The Indenture requires that prior to such a
purchase, the Company must either repay all outstanding Senior Debt or obtain
any required consents to such purchase. If a Change of Control were to occur,
the Company may not have the financial resources to repay all of the Senior
Debt, the Notes and the other indebtedness that would become payable upon the
occurrence of such Change of Control. See "Description of the Notes --
Repurchase at the Option of Holders -- Change of Control."
 
FRAUDULENT CONVEYANCE
 
     The incurrence of indebtedness (such as the Notes) is subject to review
under relevant federal and state fraudulent conveyance statutes in a bankruptcy
or reorganization case or a lawsuit by or on behalf of other creditors of the
Company. To the extent that a court were to find that (i) the Notes were
incurred with the intent to hinder, delay or defraud any present or future
creditor or that the Company contemplated insolvency with a design to favor one
or more creditors to the exclusion in whole or in part of others or (ii) the
Company did not receive fair consideration or reasonably equivalent value for
issuing the Notes and, at the time thereof, the Company (a) was insolvent or
rendered insolvent by reason of the issuance of the Notes, (b) was engaged or
about to engage in a business or transaction for which its remaining assets
constituted unreasonably small capital or (c) intended to incur, or believed
that it would incur, debts beyond its ability to pay such debts as they matured,
a court could avoid or subordinate the Notes in favor of other creditors.
 
     On the basis of historical financial information, recent operating history
as discussed in "Management's Discussion and Analysis of Financial Condition and
Results of Operations" and other information currently available to it, the
Company believes that the Notes are being incurred for proper purposes and in
good faith and that, after giving effect to indebtedness incurred in connection
with the issuance of the Notes, the Company is solvent, will have sufficient
capital for carrying on its business and will be able to pay its debts as such
debts become absolute and mature. There can be no assurance, however, that a
court passing on such questions would reach the same conclusions and, if not, a
court could, among other things, void all or a portion of the Company's
obligations to holders of Notes and/or subordinate the Company's obligations
under the Notes to a greater extent than would otherwise be the case.
 
DEPENDENCE ON KEY PERSONNEL
 
     The Company depends to a large extent on the services of certain key
management personnel. The loss of the services of such management personnel
could have a material adverse effect on the Company's operations. The Company
believes that its success is also dependent upon its ability to continue to
employ and retain skilled technical personnel. See "Management -- Employment
Agreements."
 
GOVERNMENT REGULATION AND ENVIRONMENTAL MATTERS
 
     The Company's business is regulated by certain local, state and federal
laws and regulations relating to the exploration for, and the development,
production, marketing, pricing, transportation and storage of, natural gas and
oil. The Company's business is also subject to extensive and changing
environmental and safety laws and regulations governing plugging and
abandonment, the discharge of materials into the environment or otherwise
relating to environmental protection. In addition, the Company is subject to
changing and extensive tax laws, and the effect of newly enacted tax laws cannot
be predicted. The implementation of new, or the modification of existing, laws
or regulations, including regulations which may be promulgated under the Oil
Pollution Act of 1990, could have a material adverse effect on the Company. See
"Business -- Abandonment Costs," "-- Regulation" and "-- Environmental Matters"
for a more complete description of the laws and regulations relating to the
Company's business.
 
COMPETITION
 
     The Company encounters competition from other oil and gas companies in all
areas of its operations, including the acquisition of producing properties. The
Company's competitors include major integrated oil and gas companies and
numerous independent oil and gas companies, individuals and drilling and income
 
                                       20
<PAGE>   22
 
programs. Many of its competitors are large, well-established companies with
substantially larger operating staffs and greater capital resources than the
Company's and which, in many instances, have been engaged in the oil and gas
business for a much longer time than the Company. Such companies may be able to
pay more for productive natural gas and oil properties and exploratory prospects
and to define, evaluate, bid for and purchase a greater number of properties and
prospects than the Company's financial or human resources permit. The Company's
ability to acquire additional properties and to discover reserves in the future
will be dependent upon its ability to evaluate and select suitable properties
and to consummate transactions in this highly competitive environment.
 
RELATIONSHIP WITH KEYSPAN AND POTENTIAL CONFLICTS OF INTEREST
 
     There may be conflicts of interest arising in the future between the
Company and KeySpan and its subsidiaries in a number of areas relating to their
past and ongoing relationships, including dividends, acquisitions of natural gas
and oil businesses or properties, transfers of assets, insurance matters,
marketing, financial commitments, registration rights and issuances and sales of
capital stock of the Company. As of March 31, 1998, Brooklyn Union, a wholly
owned subsidiary of KeySpan, indirectly owned approximately 64% of the Company's
outstanding Common Stock. The Company's Chairman of the Board, Robert B. Catell,
is also the Chairman of the Board of Directors and Chief Executive Officer of
Brooklyn Union. In addition, two other directors of the Company, Craig G.
Matthews and James Q. Riordan, are the President and a director of Brooklyn
Union, respectively. As a result of KeySpan's beneficial holdings of Common
Stock, KeySpan is in a position to control the election of the entire Board of
Directors of the Company and is able to control the outcome of the vote on all
matters requiring the vote of the Company's stockholders. See "Certain
Transactions."
 
CONSEQUENCES OF EXCHANGE AND FAILURE TO EXCHANGE
 
     Holders of Old Notes who do not exchange their Old Notes for Exchange Notes
pursuant to the Exchange Offer will continue to be subject to the restrictions
on transfer of such Old Notes, as set forth in the legend thereon, as a
consequence of the issuance of the Old Notes pursuant to exemptions from, or in
transactions not subject to, the registration requirements of the Securities Act
and applicable state securities laws. In general, the Old Notes may not be
offered or sold, unless registered under the Securities Act, except pursuant to
an exemption from, or in a transaction not subject to, the Securities Act and
applicable state securities laws. The Company does not currently anticipate that
it will register the Old Notes under the Securities Act. In addition, upon the
consummation of the Exchange Offer holders of Old Notes which remain outstanding
will not be entitled to any rights to have such Old Notes registered under the
Securities Act or to any similar rights under the Registration Rights Agreement,
subject to certain exceptions. To the extent that Old Notes are tendered and
accepted in the Exchange Offer, a holder's ability to sell untendered, or
tendered but unaccepted, Old Notes could be adversely affected.
 
ABSENCE OF PUBLIC MARKET FOR THE NOTES
 
     The Old Notes are currently owned by a relatively small number of
beneficial owners. The Old Notes have not been registered under the Securities
Act or any state securities laws and, unless so registered and to the extent not
exchanged for the Exchange Notes, may not be offered or sold except pursuant to
an exemption from, or in a transaction not subject to, the registration
requirements of the Securities Act and applicable state securities laws. Any Old
Notes tendered and exchanged in the Exchange Offer will reduce the aggregate
principal amount of Old Notes outstanding. Following the consummation of the
Exchange Offer, holders who did not tender their Old Notes generally will not
have any further registration rights under the Registration Rights Agreement,
and such Old Notes will continue to be subject to certain restrictions on
transfer. Accordingly, the liquidity of the market for such Old Notes could be
adversely affected. The Old Notes are currently eligible for sale pursuant to
Rule 144A in the Private Offerings, Resale and Trading through Automatic
Linkages (PORTAL) market of the National Association of Securities Dealers, Inc.
Because the Company anticipates that most holders will elect to exchange their
Old Notes for Exchange Notes due to the restrictions on the resale of Old Notes
under the Securities Act, the Company anticipates that the liquidity of
 
                                       21
<PAGE>   23
 
the market for any Old Notes remaining after the consummation of the Exchange
Offer may be substantially limited.
 
     The Exchange Notes will constitute a new issue of securities for which
there is currently no active trading market. If the Exchange Notes are traded
after their initial issuance, they may trade at a discount from their initial
offering price, depending upon prevailing interest rates, the market for similar
securities and other factors including general economic conditions and the
current financial condition, results of operations and business prospects of the
Company. Although the Exchange Notes will generally be permitted to be resold or
otherwise transferred by non-affiliates of the Company without compliance with
the registration and prospectus delivery requirements of the Securities Act, the
Company does not intend to apply for a listing or quotation of the Exchange
Notes on any securities exchange or stock market. Although one of the Initial
Purchasers has informed the Company that it currently intends to make a market
in the Exchange Notes, it is not obligated to do so, and any such market-making
may be discontinued at any time without notice. In addition, such market-making
activity will be subject to the limits imposed under the Exchange Act.
Accordingly, there can be no assurance as to the development, liquidity or
maintenance of any market for the Exchange Notes. If no trading market develops
or is maintained for the Exchange Notes, holders may experience difficulty in
reselling the Exchange Notes or may be unable to sell them.
 
     The liquidity of, and trading market for, the Old Notes or the Exchange
Notes also may be adversely affected by general declines in the market for
similar securities. Such a decline may adversely affect such liquidity and
trading markets independent of the financial performance of, and prospects for,
the Company.
 
                                       22
<PAGE>   24
 
                                  THE COMPANY
 
     Houston Exploration is an independent natural gas and oil company engaged
in the exploration, development and acquisition of domestic natural gas and oil
properties. The Company's offshore properties are located primarily in the
shallow waters (up to 600 feet) of the Gulf of Mexico, and its onshore
properties are located in South Texas, the Arkoma Basin, East Texas and West
Virginia. At December 31, 1997, the Company had net proved reserves of 337 Bcfe.
Approximately 98% of the Company's net proved reserves on such date were natural
gas and approximately 78% of net proved reserves were classified as proved
developed. The Company operates over 90% of its production. The Company believes
its primary strengths are its high quality reserves, its substantial inventory
of exploration and development opportunities, its in-house expertise in
generating new prospects, and its geographic focus and low-cost operating
structure.
 
     The Company was incorporated in Delaware in December 1985 to conduct
certain of the natural gas and oil exploration and development activities in
Brooklyn Union. The Company initially focused primarily on the exploration and
development of high potential prospects in the Gulf of Mexico. Effective
February 29, 1996, Brooklyn Union implemented a reorganization of its
exploration and production assets by transferring to Houston Exploration certain
onshore producing properties and developed and undeveloped acreage. Subsequent
to the reorganization, the Company has expanded its focus to include lower risk
exploitation and development drilling on the onshore properties transferred, in
addition to seeking opportunistic acquisitions both onshore and offshore. On
July 2, 1996, the Company acquired certain natural gas and oil properties and
associated pipelines located in Zapata County, Texas from TransTexas Gas
Corporation and TransTexas Transmission Corporation (together, "TransTexas") for
a net purchase price of approximately $56 million. In September 1996, the
Company completed its IPO of 7,130,000 shares of Common Stock. Concurrently with
the completion of its IPO, the Company completed the acquisition of
substantially all of the natural gas and oil properties and related assets of
Smith Offshore Exploration Company ("Soxco") for a net purchase price consisting
of approximately $20.3 million in cash and 762,387 shares of Common Stock with
an aggregate value (determined by reference to the IPO price) of $11.8 million.
In addition, the Company agreed to pay to Soxco effective January 31, 1998 a
deferred purchase price, payable in shares of the Company's Common Stock, of not
more than $17.6 million and not less than $8.8 million as determined by Soxco's
probable reserves as of December 31, 1995 that are produced or classified as
proved prior to December 31, 1997. The Company paid the deferred purchase price
in the first quarter of 1998 by delivering 520,777 shares of Common Stock with
an aggregate value (determined by reference to a 20 trading day average price of
the Common Stock) of $8.8 million. As of March 31, 1998, THEC Holdings Corp., a
wholly owned subsidiary of Brooklyn Union, owned approximately 64% of the
outstanding shares of Common Stock. Brooklyn Union, which in September 1997
became a wholly owned subsidiary of KeySpan, distributes natural gas in an area
of New York City with a population of four million.
 
     The Company's principal executive offices are located at 1100 Louisiana,
Suite 2000, Houston, Texas 77002 and its telephone number is (713) 830-6800.
 
                                       23
<PAGE>   25
 
                               THE EXCHANGE OFFER
 
PURPOSE AND EFFECT OF THE EXCHANGE OFFER
 
     The Old Notes were sold by the Company on March 2, 1998 to the Initial
Purchasers pursuant to a Purchase Agreement, dated February 25, 1998, between
the Company and the Initial Purchasers (the "Purchase Agreement"). The Initial
Purchasers subsequently resold all of the Old Notes to Qualified Institutional
Buyers, each of whom agreed to comply with certain transfer restrictions and
other conditions. As a condition to the purchase of the Old Notes by the Initial
Purchasers, the Company entered into a registration rights agreement with the
Initial Purchasers (the "Registration Rights Agreement"), which requires, among
other things, that promptly following the issuance and sale of the Old Notes,
the Company file with the SEC the Registration Statement with respect to the
Exchange Notes, use its best efforts to cause the Registration Statement to
become effective under the Securities Act and, upon the effectiveness of the
Registration Statement, offer to the holders of the Old Notes the opportunity to
exchange their Old Notes for a like principal amount of Exchange Notes, which
will be issued without a restrictive legend and may be reoffered and resold by
the holder without restrictions or limitations under the Securities Act subject
to certain exceptions described below. A copy of the Registration Rights
Agreement has been filed as an exhibit to the Registration Statement of which
this Prospectus is a part. The term "holder" with respect to the Exchange Offer
means any person in whose name Old Notes are registered on the Company's books
or any other person who has obtained a properly completed bond power from the
registered holder or any person whose Old Notes are held of record by the
Depositary who desires to deliver such Old Notes by book-entry transfer of the
Depositary.
 
     Based on existing interpretations of the Securities Act by the staff of the
SEC set forth in several no-action letters to third parties, and subject to the
immediately following sentence, the Company believes that Exchange Notes issued
pursuant to the Exchange Offer in exchange for Old Notes may be offered for
resale, resold and otherwise transferred by a holder thereof (other than (i) a
broker-dealer who purchased such Old Notes directly from the Company for resale
pursuant to Rule 144A or any other available exemption under the Securities Act
or (ii) a person that is an "affiliate" (within the meaning of Rule 405 of the
Securities Act) of the Company), without compliance with the registration and
prospectus delivery provisions of the Securities Act, provided that the holder
is acquiring the Exchange Notes in its ordinary course of business and is not
participating, and has no arrangement or understanding with any person to
participate, in the distribution of the Exchange Notes. However, any purchaser
of Old Notes who is an affiliate of the Company or who intends to participate in
the Exchange Offer for the purpose of distributing the Exchange Notes, or any
broker-dealer who purchased the Old Notes from the Company to resell pursuant to
Rule 144A or any other available exemption under the Securities Act, (i) will
not be able to rely on the interpretations by the staff of the SEC set forth in
the above-mentioned no-action letters, (ii) will not be able to tender its Old
Notes in the Exchange Offer and (iii) must comply with the registration and
prospectus delivery requirements of the Securities Act in connection with any
sale or transfer of the Old Notes unless such sale or transfer is made pursuant
to an exemption from such requirements. Accordingly, any holder who tenders in
the Exchange Notes must comply with the registration and prospectus delivery
requirements of the Securities Act in connection with a secondary resale
transaction. See "Plan of Distribution."
 
     As a result of the filing and effectiveness of the Registration Statement
of which this Prospectus is a part, the Company will not be required to pay an
increased interest rate on the Old Notes. Following the consummation of the
Exchange Offer, holders of Old Notes not tendered will not have any further
registration rights except in certain limited circumstances requiring the filing
of a Shelf Registration Statement (as defined herein), and the Old Notes will
continue to be subject to certain restrictions on transfer. See "Description of
the Notes -- Registered Exchange Offer; Registration Rights." Accordingly, the
liquidity of the market for the Old Notes could be adversely affected.
 
TERMS OF THE EXCHANGE OFFER
 
     Upon the terms and subject to the conditions set forth in this Prospectus
and in the Letter of Transmittal, the Company will accept all Old Notes properly
tendered and not withdrawn prior to 5:00 p.m. New York City
                                       24
<PAGE>   26
 
time, on the Expiration Date. After authentication of the Exchange Notes by the
Trustee or an authenticating agent, the Company will issue and deliver $1,000
principal amount of Exchange Notes in exchange for each $1,000 principal amount
of outstanding Old Notes accepted in the Exchange Offer. Holders may tender some
or all of their Old Notes pursuant to the Exchange Offer in denominations of
$1,000 and integral multiples thereof.
 
     Each holder of Old Notes who wishes to exchange Old Notes for Exchange
Notes in the Exchange Offer will be required to represent that (i) it is not an
affiliate of the Company, (ii) any Exchange Notes to be received by it were
acquired in the ordinary course of its business and (iii) it has no arrangement
or understanding with any person to participate in the distribution (within the
meaning of the Securities Act) of the Exchange Notes.
 
     Each broker-dealer that receives Exchange Notes for its own account in
exchange for Old Notes, where such Old Notes were acquired by such broker-dealer
as a result of market-making activities or other trading activities, must
acknowledge that it will deliver a prospectus in connection with any resale of
such Exchange Notes. See "Plan of Distribution."
 
     The form and terms of the Exchange Notes are identical in all material
respects to the form and terms of the Old Notes, except that (i) the offering of
the Exchange Notes has been registered under the Securities Act, (ii) the
Exchange Notes will not be subject to transfer restrictions and (iii) certain
provisions relating to an increase in the stated interest rate on the Old Notes
provided for under certain circumstances will be eliminated. The Exchange Notes
will evidence the same debt as the Old Notes. The Exchange Notes will be issued
under and entitled to the benefits of the Indenture.
 
     As of the date of this Prospectus, $100,000,000 aggregate principal amount
of the Old Notes is outstanding. In connection with the issuance of the Old
Notes, the Company arranged for the Old Notes to be issued and transferable in
book-entry form through the facilities of the Depositary, acting as depositary.
The Exchange Notes will also be issuable and transferable in book-entry form
through the Depositary.
 
     This Prospectus, together with the accompanying Letter of Transmittal, is
initially being sent to all registered holders of the Old Notes as of the close
of business on May 14, 1998. The Company intends to conduct the Exchange Offer
in accordance with the applicable requirements of the Exchange Act, and the
rules and regulations of the SEC thereunder, including Rule 14e-1, to the extent
applicable. The Exchange Offer is not conditioned upon any minimum aggregate
principal amount of Old Notes being tendered, and holders of the Old Notes do
not have any appraisal or dissenters' rights under the General Corporation Law
of the State of Delaware or under the Indenture in connection with the Exchange
Offer. The Company shall be deemed to have accepted validly tendered Old Notes
when, as and if the Company has given oral or written notice thereof to the
Exchange Agent. See "-- Exchange Agent." The Exchange Agent will act as agent
for the tendering holders for the purpose of receiving Exchange Notes from the
Company and delivering Exchange Notes to such holders.
 
     If any tendered Old Notes are not accepted for exchange because of an
invalid tender or the occurrence of certain other events set forth herein,
certificates for any such unaccepted Old Notes will be returned, at the
Company's cost, to the tendering holder thereof as promptly as practicable after
the Expiration Date.
 
     Holders who tender Old Notes in the Exchange Offer will not be required to
pay brokerage commissions or fees or, subject to the instructions in the Letter
of Transmittal, transfer taxes with respect to the exchange of Old Notes
pursuant to the Exchange Offer. The Company will pay all charges and expenses,
other than certain applicable taxes, in connection with the Exchange Offer. See
"-- Solicitation of Tenders, Fees and Expenses."
 
     NEITHER THE BOARD OF DIRECTORS OF THE COMPANY NOR THE COMPANY MAKES ANY
RECOMMENDATION TO HOLDERS OF OLD NOTES AS TO WHETHER TO TENDER OR REFRAIN FROM
TENDERING ALL OR ANY PORTION OF THEIR OLD NOTES PURSUANT TO THE EXCHANGE OFFER.
MOREOVER, NO ONE HAS BEEN AUTHORIZED TO MAKE ANY SUCH RECOMMENDATION. HOLDERS OF
OLD NOTES MUST MAKE THEIR OWN DECISION WHETHER TO TENDER PURSUANT TO THE
EXCHANGE OFFER AND, IF SO, THE AGGRE-
                                       25
<PAGE>   27
 
GATE AMOUNT OF OLD NOTES TO TENDER AFTER READING THIS PROSPECTUS AND THE LETTER
OF TRANSMITTAL AND CONSULTING WITH THEIR ADVISORS, IF ANY, BASED ON THEIR OWN
FINANCIAL POSITION AND REQUIREMENTS.
 
EXPIRATION DATE; EXTENSIONS; AMENDMENTS
 
     The term "Expiration Date" shall mean 5:00 p.m., New York City time, on
June 14, 1998 unless the Company, in its sole discretion, extends the Exchange
Offer, in which case the term "Expiration Date" shall mean the latest date to
which the Exchange Offer is extended. The Company may extend the Exchange Offer
at any time and from time to time by giving oral or written notice to the
Exchange Agent and by timely public announcement.
 
     The Company expressly reserves the right, in its sole discretion (i) to
delay acceptance of any Old Notes, to extend the Exchange Offer or to terminate
the Exchange Offer and to refuse to accept Old Notes not previously accepted, if
any of the conditions set forth herein under "-- Conditions of the Exchange
Offer" shall have occurred and shall not have been waived by the Company (if
permitted to be waived by the Company), by giving oral or written notice of such
delay, extension or termination to the Exchange Agent and (ii) to amend the
terms of the Exchange Offer in any manner. Any such delay in acceptance,
extension, termination or amendment will be followed as promptly as practicable
by oral or written notice thereof by the Company to the registered holders of
the Old Notes. If the Exchange Offer is amended in a manner determined by the
Company to constitute a material change, the Company will promptly disclose such
amendment in a manner reasonably calculated to inform the holders of such
amendment and the Company will extend the Exchange Offer to the extent required
by law.
 
     Without limiting the manner in which the Company may choose to make public
announcements of any delay in acceptance, extension, termination or amendment of
the Exchange Offer, the Company shall have no obligation to publish, advise, or
otherwise communicate any such public announcement, other than by making a
timely release thereof to the Dow Jones News Service.
 
INTEREST ON THE EXCHANGE NOTES
 
     The Exchange Notes will bear interest at a rate of 8 5/8% per annum,
payable semi-annually on January 1 and July 1 of each year, commencing July 1,
1998. Holders of Exchange Notes of record on June 15, 1998 will receive on July
1, 1998 an interest payment in an amount equal to (x) the accrued interest on
such Exchange notes from the date of issuance thereof to July 1, 1998, plus (y)
the accrued interest on the previously held Old Notes from the date of issuance
of such Old Notes (March 2, 1998) to the date of exchange thereof. Interest will
not be paid on Old Notes that are accepted for exchange. The Notes mature on
January 1, 2008.
 
PROCEDURES FOR TENDERING
 
     Each holder of Old Notes wishing to accept the Exchange Offer must
complete, sign and date the Letter of Transmittal, or a facsimile thereof, in
accordance with the instructions contained herein and therein, and mail or
otherwise deliver such Letter of Transmittal, or such facsimile, together with
the Old Notes to be exchanged and any other required documentation, to The Bank
of New York, as Exchange Agent, at the address set forth herein and therein or
effect a tender of Old Notes pursuant to the procedures for book-entry transfer
as provided for herein and therein. By executing the Letter of Transmittal, each
holder will represent to the Company, that, among other things, the Exchange
Notes acquired pursuant to the Exchange Offer are being acquired in the ordinary
course of business of the person receiving such Exchange Notes, whether or not
such person is the holder, that neither the holder nor any such other person has
any arrangement or understanding with any person to participate in the
distribution of such Exchange Notes and that neither the holder nor any such
other person is an "affiliate," as defined in Rule 405 under the Securities Act,
of the Company.
 
     Any financial institution that is a participant in the Depositary's
Book-Entry Transfer Facility system may make book-entry delivery of the Old
Notes by causing the Depositary to transfer such Old Notes into the Exchange
Agent's account in accordance with the Depositary's procedure for such transfer.
Although delivery
                                       26
<PAGE>   28
 
of Old Notes may be effected through book-entry transfer into the Exchange
Agent's account at the Depositary, the Letter of Transmittal (or facsimile
thereof), with any required signature guarantees and any other required
documents, must, in any case, be transmitted to and received by the Exchange
Agent at its address set forth herein under "-- Exchange Agent" prior to 5:00
p.m., New York City time, on the Expiration Date. DELIVERY OF DOCUMENTS TO THE
DEPOSITARY IN ACCORDANCE WITH ITS PROCEDURES DOES NOT CONSTITUTE DELIVERY TO THE
EXCHANGE AGENT.
 
     Only a holder may tender its Old Notes in the Exchange Offer. To tender in
the Exchange Offer, a holder must complete, sign and date the Letter of
Transmittal or a facsimile thereof, have the signatures thereof guaranteed if
required by the Letter of Transmittal, and mail or otherwise deliver such Letter
of Transmittal or such facsimile, together with the Old Notes (unless such
tender is being effected pursuant to the procedure for book-entry transfer) and
any other required documents, to the Exchange Agent, prior to 5:00 p.m., New
York City time, on the Expiration Date.
 
     The Tender by a holder will constitute an agreement between such holder,
the Company and the Exchange Agent in accordance with the terms and subject to
the conditions set forth herein and in the Letter of Transmittal. If less than
all of the Old Notes are tendered, a tendering holder should fill in the amount
of Old Notes being tendered in the appropriate box on the Letter of Transmittal.
The entire amount of Old Notes delivered to the Exchange Agent will be deemed to
have been tendered unless otherwise indicated.
 
     THE LETTER OF TRANSMITTAL WILL INCLUDE REPRESENTATIONS TO THE COMPANY THAT,
AMONG OTHER THINGS, (1) THE EXCHANGE NOTES ACQUIRED PURSUANT TO THE EXCHANGE
OFFER ARE BEING ACQUIRED IN THE ORDINARY COURSE OF BUSINESS OF THE PERSON
RECEIVING SUCH EXCHANGE NOTES (WHETHER OR NOT SUCH PERSON IS THE HOLDER), (2)
NEITHER THE HOLDER NOR ANY SUCH OTHER PERSON IS ENGAGED IN, INTENDS TO ENGAGE IN
OR HAS ANY ARRANGEMENT OR UNDERSTANDING WITH ANY PERSON TO PARTICIPATE IN THE
DISTRIBUTION OF SUCH EXCHANGE NOTES, (3) NEITHER THE HOLDER NOR ANY SUCH OTHER
PERSON IS AN "AFFILIATE," AS DEFINED IN RULE 405 UNDER THE SECURITIES ACT, OF
THE COMPANY AND (4) IF THE TENDERING HOLDER IS A BROKER OR DEALER (AS DEFINED IN
THE EXCHANGE ACT) (A) IT ACQUIRED THE OLD NOTES FOR ITS OWN ACCOUNT AS A RESULT
OF MARKET-MAKING ACTIVITIES OR OTHER TRADING ACTIVITIES AND (B) IT HAS NOT
ENTERED INTO ANY ARRANGEMENT OR UNDERSTANDING WITH THE COMPANY OR ANY
"AFFILIATE" THEREOF (WITHIN THE MEANING OF RULE 405 UNDER THE SECURITIES ACT) TO
DISTRIBUTE THE EXCHANGE NOTES TO BE RECEIVED IN THE EXCHANGE OFFER. IN THE CASE
OF A BROKER-DEALER THAT RECEIVES EXCHANGE NOTES FOR ITS OWN ACCOUNT IN EXCHANGE
FOR OLD NOTES WHICH WERE ACQUIRED BY IT AS A RESULT OF MARKET-MAKING OR OTHER
TRADING ACTIVITIES, THE LETTER OF TRANSMITTAL WILL ALSO INCLUDE AN
ACKNOWLEDGMENT THAT THE BROKER-DEALER WILL DELIVER A COPY OF THIS PROSPECTUS IN
CONNECTION WITH THE RESALE BY IT OF EXCHANGE NOTES RECEIVED PURSUANT TO THE
EXCHANGE OFFER, HOWEVER, BY SO ACKNOWLEDGING AND BY DELIVERING A PROSPECTUS,
SUCH HOLDER WILL NOT BE DEEMED TO ADMIT THAT IT IS AN "UNDERWRITER" WITHIN THE
MEANING OF THE SECURITIES ACT. SEE "PLAN OF DISTRIBUTION."
 
     THE METHOD OF DELIVERY OF OLD NOTES AND THE LETTER OF TRANSMITTAL AND ALL
OTHER REQUIRED DOCUMENTS TO THE EXCHANGE AGENT IS AT THE ELECTION AND RISK OF
THE HOLDERS. INSTEAD OF DELIVERY BY MAIL, IT IS RECOMMENDED THAT HOLDERS USE AN
OVERNIGHT OR HAND DELIVERY SERVICE. IN ALL CASES, SUFFICIENT TIME SHOULD BE
ALLOWED TO ENSURE DELIVERY TO THE EXCHANGE AGENT PRIOR TO THE EXPIRATION DATE.
NO LETTER OF TRANSMITTAL OR OLD NOTES SHOULD BE SENT TO THE COMPANY. HOLDERS MAY
ALSO REQUEST THAT THEIR RESPECTIVE BROKERS, DEALERS, COMMERCIAL BANKS, TRUST
COMPANIES OR NOMINEES EFFECT SUCH TENDER FOR HOLDERS, IN EACH CASE AS SET FORTH
HEREIN AND IN THE LETTER OF TRANSMITTAL.
 
     Any beneficial owner whose Old Notes are registered in the name of his
broker, dealer, commercial bank, trust company or other nominee and who wishes
to tender should contact such registered holder promptly and instruct such
registered holder to tender on his behalf. If such beneficial owner wishes to
tender on his own behalf, such beneficial owner must, prior to completing and
executing the Letter of Transmittal and delivering his Old Notes, either make
appropriate arrangements to register ownership of the Old Notes in such owner's
 
                                       27
<PAGE>   29
 
name or obtain a properly completed bond power from the registered holder. The
transfer of record ownership may take considerable time.
 
     Signatures on a Letter of Transmittal or a notice of withdrawal, as the
case may be, must be guaranteed by a member firm of a registered national
securities exchange or of the National Association of Securities Dealers, Inc.,
a commercial bank or trust company having an office or correspondent in the
United States or an "eligible guarantor institution" within the meaning of Rule
17Ad-15 under the Exchange Act (each an "Eligible Institution"), unless the Old
Notes tendered pursuant thereto are tendered (i) by a registered holder who has
not completed the box entitled "Special Registration Instructions" or "Special
Delivery Instructions" of the Letter of Transmittal or (ii) for the account of
an Eligible Institution. If the Letter of Transmittal is signed by a person
other than the registered holder listed therein, such Old Notes must be endorsed
or accompanied by appropriate bond powers which authorize such person to tender
the Old Notes on behalf of the registered holder, in either case signed as the
name of the registered holder or holders appears on the Old Notes. If the Letter
of Transmittal or any Old Notes or bond powers are signed or endorsed by
trustees, executors, administrators, guardians, attorneys-in-fact, officers of
corporations or others acting in a fiduciary or representative capacity, such
person should so indicate when signing, and unless waived by the Company.
evidence satisfactory to the Company of their authority to so act must be
submitted with such Letter of Transmittal.
 
     All questions as to the validity, form, eligibility (including time of
receipt), acceptance and withdrawal of the tendered Old Notes will be determined
by the Company in its sole discretion, which determination will be final and
binding, The Company reserves the absolute right to reject any and all Old Notes
not properly tendered or any Old Notes the Company's acceptance of which would,
in the opinion of counsel for the Company, be unlawful. The Company also
reserves the absolute right to waive an irregularities or conditions of tender
as to particular Old Notes. The Company's interpretation of the terms, and
conditions of the Exchange Offer (including the instructions in the Letter of
Transmittal) will be final and binding on all parties. Unless waived, any
defects or irregularities in connection with tenders of Old Notes must be cured
within such time as the Company shall determine. Although the Company intends to
notify holders of defects or irregularities with respect to tenders of Old
Notes, neither the Company, the Exchange Agent nor any other person shall be
under any duty to give notification of defects or irregularities with respect to
tenders of Old Notes, nor shall any of them incur any liability for failure to
give such notification. Tenders of Old Notes will not be deemed to have been
made until such irregularities have been cured or waived. Any Old Notes received
by the Exchange Agent that the Company determines are not properly tendered or
the tender of which is otherwise rejected by the Company and as to which the
defects or irregularities have not been cured or waived by the Company will be
returned by the Exchange Agent to the tendering holder unless otherwise provided
in the Letter of Transmittal, as soon as practicable following the Expiration
Date.
 
     In addition, the Company reserves the right in its sole discretion (a) to
purchase or make offers for any Old Notes that remain outstanding subsequent to
the Expiration Date, or, as set forth under "-- Conditions of the Exchange
Offer," terminate the Exchange Offer and (b) to the extent permitted by
applicable law, to purchase Old Notes in the open market, in privately
negotiated transactions or otherwise. The terms of any such purchases or offers
may differ from the terms of the Exchange Offer.
 
BOOK-ENTRY TRANSFER
 
     The Company understands that the Exchange Agent will make a request
promptly after the date-of this Prospectus to establish accounts with respect to
the Old Notes at the DTC (the "Book-Entry Transfer Facility") for the purpose of
facilitating the Exchange Offer, and subject to the establishment thereof, any
financial institution that is a participant in the Book-Entry Transfer
Facility's system may make book-entry deliver of Old Notes by causing such
BookEntry Transfer Facility to transfer such Old Notes into the Exchange Agent's
account with respect to the Old Notes in accordance with the Book-Entry Transfer
Facility's procedures for such transfer. ALTHOUGH DELIVERY OF OLD NOTES MAY BE
EFFECTED THROUGH BOOK-ENTRY TRANSFER INTO THE EXCHANGE AGENT'S ACCOUNT AT THE
BOOK-ENTRY TRANSFER FACILITY, AN APPROPRIATE LETTER OF TRANSMITTAL PROPERLY
COMPLETED AND DULY EXECUTED WITH ANY REQUIRED SIGNATURE GUARANTEE AND ALL OTHER
REQUIRED DOCUMENTS MUST IN EACH CASE BE TRANSMITTED TO AND RECEIVED OR CONFIRMED
BY THE EXCHANGE AGENT AT
                                       28
<PAGE>   30
 
ITS ADDRESS SET FORTH BELOW ON OR PRIOR TO THE EXPIRATION DATE, OR, IF THE
GUARANTEED DELIVERY PROCEDURES DESCRIBED BELOW ARE COMPLIED WITH, WITH THE TIME
PERIOD PROVIDED UNDER SUCH PROCEDURES. DELIVERY OF DOCUMENTS TO THE BOOK-ENTRY
TRANSFER FACILITY DOES NOT CONSTITUTE DELIVERY TO THE EXCHANGE AGENT.
 
GUARANTEED DELIVERY PROCEDURES
 
     Holders who wish to tender their Old Notes and (i) whose Old Notes are not
immediately available, or (ii) who cannot deliver their Old Notes, the Letter of
Transmittal or any other required documents to the Exchange Agent prior to the
Expiration Date, or who cannot complete the procedure for book-entry transfer on
a timely basis, may effect a tender if:
 
          (a) the tender is made through an Eligible Institution;
 
          (b) prior to the Expiration Date, the Exchange Agent receives from
     such Eligible Institution a properly completed and duly executed Notice of
     Guaranteed Delivery (by facsimile transmittal, mail or hand delivery)
     setting forth the name and address of the holder, the certificate number or
     numbers of such holder's Old Notes and the principal amount of such Old
     Notes tendered, stating that the tender is being made thereby, and
     guaranteeing that, within three New York Stock Exchange ("NYSE") trading
     days after the Expiration Date, the Letter of Transmittal (or facsimile
     thereof), together with the certificate(s) representing the Old Notes to be
     tendered in proper form for transfer (or confirmation of a book-entry
     transfer into the Exchange Agent's account at the Depositary of Old Notes
     delivered electronically) and any other documents required by the Letter of
     Transmittal, will be deposited by the Eligible Institution with the
     Exchange Agent; and
 
          (c) such properly completed and executed Letter of Transmittal (or
     facsimile thereof), together with the certificate(s) representing all
     tendered Old Notes in proper form for transfer (or confirmation of a
     book-entry transfer into the Exchange Agent's account at the Depositary of
     Old Notes delivered electronically) and all other documents required by the
     Letter of Transmittal are received by the Exchange Agent within three NYSE
     trading days after the Expiration Date.
 
     Upon request to the Exchange Agent, a Notice of Guaranteed Delivery will be
sent to holders who wish to tender their Old Notes according to the guaranteed
delivery procedures set forth above.
 
WITHDRAWAL OF TENDERS
 
     Except as otherwise provided herein, tenders of Old Notes may be withdrawn
at any time prior to 5:00 p.m., New York City time, on the Expiration Date.
 
     For a withdrawal to be effective, a written or facsimile transmission
notice of withdrawal must be received by the Exchange Agent at its address set
forth herein prior to 5:00 p.m., New York City time, on the Expiration Date. Any
such notice of withdrawal must (i) specify the name of the person having
deposited the Old Notes to be withdrawn (the "Depositor"), (ii) identify the Old
Notes to be withdrawn (including the certificate number or numbers and principal
amount of such Old Notes or, in the case of Old Notes transferred by book-entry
transfer, the name and number of the account at the Depositary to be credited),
(iii) be signed by the Depositor in the same manner as the original signature on
the Letter of Transmittal, by which such Old Notes were tendered (including any
required signature guarantee) or be accompanied by documents of transfer
sufficient to permit the Trustee with respect to the Old Notes to register the
transfer of such Old Notes into the name of the Depositor withdrawing the tender
and (iv) specify the name in which any such Old Notes are to be registered, if
different from that of the Depositor. All questions as to the validity, form and
eligibility (including time of receipt) of such withdrawal notices will be
determined by the Company, whose determination shall be final and binding on all
parties. Any Old Notes so withdrawn will be deemed not to have been validly
tendered for purposes of the Exchange Offer, and no Exchange Notes will be
issued with respect thereto unless the Old Notes so withdrawn are validly
retendered. Any Old Notes that have been tendered but are not accepted for
exchange will be returned to the holder thereof without cost to such holder as
soon as practicable after withdrawal, rejection of tender or termination of the
Exchange Offer.
 
                                       29
<PAGE>   31
 
Properly withdrawn Old Notes may be retendered by following one of the
procedures described above under "-- Procedures for Tendering" at any time prior
to the Expiration Date.
 
CONDITIONS TO THE EXCHANGE OFFER
 
     Notwithstanding any other term of the Exchange Offer, the Company will not
be required to accept for exchange, or to Exchange Notes for, any Old Notes, and
may terminate or amend the Exchange Offer as provided herein before the
acceptance of such Old Notes if, in the Company's judgment, any of the following
conditions has occurred or exists or has not been satisfied: (i) that the
Exchange Offer, or the making of any exchange by a holder, violates applicable
law or any applicable interpretation of the staff of the SEC, (ii) that any
action or proceeding shall have been instituted or threatened in any court or by
or before any governmental agency or body with respect to the Exchange Offer,
(iii) that there has been adopted or enacted any law, statute, rule or
regulation that can reasonably be expected to impair the ability of the Company
to proceed with the Exchange Offer, (iv) that there has been declared by United
States federal or Texas or New York state authorities a banking moratorium; or
(v) that trading on the New York Stock Exchange or generally in the United
States over-the-counter market has been suspended by order of the SEC or any
other governmental agency, in each of clauses (i) through (iv) which, in the
Company's judgment, would reasonably be expected to impair the ability of the
Company to proceed with the Exchange Offer.
 
     If the Company determines that it may terminate the Exchange Offer for any
of the reasons set forth above, the Company may (i) refuse to accept any Old
Notes and return any Old Notes that have been tendered to the holders thereof,
(ii) extend the Exchange Offer and retain all Old Notes tendered prior to the
Expiration Date of the Exchange Offer, subject to the rights of such holders of
tendered Old Notes to withdraw their tendered Old Notes or (iii) waive such
termination event with respect to the Exchange Offer and accept all properly
tendered Old Notes that have not been withdrawn. If such waiver constitutes a
material change in the Exchange Offer, the Company will disclose such change by
means of a supplement to this Prospectus that will be distributed to each
registered holder, and the Company will extend the Exchange Offer for a period
of five to ten business days, depending upon the significance of the waiver and
the manner of disclosure to the registered holders, if the Exchange Offer would
otherwise expire during such period.
 
EXCHANGE AGENT
 
     The Bank of New York, the Trustee under the Indenture, has been appointed
as Exchange Agent for the Exchange Offer. In such capacity, the Exchange Agent
has no fiduciary duties and will be acting solely on the basis of directions of
the Company. Requests for assistance and requests for additional copies of this
Prospectus or of the Letter of Transmittal should be directed to the Exchange
Agent addressed as follows:
 
                      The Bank of New York, Exchange Agent
 
<TABLE>
<S>                             <C>                             <C>
  By Registered or Certified      By Facsimile Transmission:    By Overnight or Hand Delivery:
              Mail:
     The Bank of New York         (for Eligible Institutions         The Bank of New York
                                            only):
    101 Barclay Street, 7E              (212) 815-6339                101 Barclay Street
   New York, New York 10286         Attention: Marcia Brown     Corporate Trust Services Window
    Attention: Marcia Brown                                              Ground Level
                                     Confirm by Telephone:         New York, New York 10286
                                        (212) 815-3428              Attention: Marcia Brown
</TABLE>
 
     DELIVERY OF THE LETTER OF TRANSMITTAL TO AN ADDRESS OTHER THAN AS SET FORTH
ABOVE OR TRANSMISSION OF INSTRUCTIONS VIA FACSIMILE OTHER THAN AS SET FORTH
ABOVE WILL NOT CONSTITUTE A VALID DELIVERY OF SUCH LETTER OF TRANSMITTAL.
 
                                       30
<PAGE>   32
 
SOLICITATION OF TENDERS; FEES AND EXPENSES
 
     The expenses of soliciting tenders pursuant to the Exchange Offer will be
borne by the Company. The principal solicitation pursuant to the Exchange Offer
is being made by mail. Additional solicitations may be made by officers and
regular employees of the Company and its affiliates in person, by telegraph,
telephone or telecopier.
 
     The Company has not retained any dealer-manager in connection with the
Exchange Offer and will not make any payments to brokers, dealers or other
persons soliciting acceptances of the Exchange Offer. The Company will, however,
pay the Exchange Agent reasonable and customary fees for its services and will
reimburse the Exchange Agent for its reasonable out-of-pocket costs and expenses
in connection therewith and will indemnify the Exchange Agent for all losses and
claims incurred by it as a result of the Exchange Offer. The Company may also
pay brokerage houses and other custodians, nominees and fiduciaries the
reasonable out-of-pocket expenses incurred by them in forwarding copies of this
Prospectus, Letters of Transmittal and related documents to the beneficial
owners of the Old Notes and in handling or forwarding tenders for exchange.
 
     The expenses to be incurred in connection with the Exchange Offer,
including fees and expenses of the Exchange Agent and Trustee and accounting and
legal fees and printing costs, will be paid by the Company.
 
     The Company will pay all transfer taxes, if any, applicable to the exchange
of Old Notes pursuant to the Exchange Offer. If, however, certificates
representing Exchange Notes or Old Notes for principal amounts not tendered or
accepted for exchange are to be delivered to, or are to be registered or issued
in the name of, any person other than the registered holder of the Old Notes
tendered, or if tendered Old Notes are registered in the name of any person
other than the person signing the Letter of Transmittal, or if a transfer tax is
imposed for any reason other than the exchange of Old Notes pursuant to the
Exchange Offer, then the amount of any such transfer taxes (whether imposed on
the registered holder or any other persons) will be payable by the tendering
holder. If satisfactory evidence of payment of such taxes or exemption therefrom
is not submitted with the Letter of Transmittal, the amount of such transfer
taxes will be billed by the Company directly to such tendering holder.
 
ACCOUNTING TREATMENT
 
     The Exchange Notes will be recorded at the same carrying value as the Old
Notes, as reflected in the Company's accounting records on the date of the
exchange. Accordingly, no gain or loss for accounting purposes will be
recognized by the Company as a result of the consummation of the Exchange Offer.
The expenses of the Exchange Offer will be amortized by the Company over the
term of the Exchange Notes.
 
CONSEQUENCES OF FAILURE TO EXCHANGE
 
     Participation in the Exchange Offer is voluntary. Holders of the Old Notes
are urged to consult their financial and tax advisors in making their own
decisions as to what action to take.
 
     As a result of the making of, and upon acceptance for exchange of all
validly tendered Old Notes pursuant to the terms of, this Exchange Offer, the
Company will have fulfilled a covenant contained in the Registration Rights
Agreement. Holders of the Old Notes who do not tender their Old Notes in the
Exchange Offer will continue to hold such Old Notes and will be entitled to all
the rights, and subject to the limitations applicable thereto, under the
Indenture and the Registration Rights Agreement, except for any such rights
under the Registration Rights Agreement that by their terms terminate or cease
to have further effect as a result of the malting of this Exchange Offer. See
"Description of the Notes." All untendered Old Notes will continue to be subject
to the restrictions on transfer set forth in the Indenture. The Old Notes may
not be offered, resold, pledged or otherwise transferred, prior to the date that
is two years after the later of March 2, 1998 (the date of the issuance of the
Old Notes) and the last date on which the Company or any "affiliate" (within the
meaning of Rule 144 of the Securities Act) of the Company was the owner of such
Old Note except (i) to the Company, (ii) pursuant to a registration statement
which has been declared effective under the Securities Act, (iii) to Qualified
Institutional Buyers in reliance upon the exemption from the registration
 
                                       31
<PAGE>   33
 
requirements of the Securities Act provided by Rule 144A, (v) to institutional
"accredited investors" (as defined in Rule 501 (a) (1), (2), (3) or (7) under
the Securities Act) in transactions exempt from the registration requirements of
the Securities Act, (v) in transactions complying with the provisions of
Regulation S under the Securities Act or (vi) pursuant to any other available
exemption from the registration requirements under the Securities Act. To the
extent that Old Notes are tendered and accepted in the Exchange Offer, the
liquidity of the trading market for untendered Old Notes could be adversely
affected.
 
     The Company may in the future seek to acquire untendered Old Notes in the
open market or through privately negotiated transactions, through subsequent
exchange offers or otherwise. The Company intends to make any such acquisitions
of Old Notes in accordance with the applicable requirements of the Exchange Act
and the rules and regulations of the SEC thereunder, including Rule 14e-1, to
the extent applicable. The Company has no present plan to acquire any Old Notes
that are not tendered in the Exchange Offer or to file a registration statement
to permit resales of any Old Notes that are not tendered in the Exchange Offer.
 
                                USE OF PROCEEDS
 
     The Company will not receive any cash proceeds from the issuance of the
Exchange Notes offered hereby. In consideration for issuing the Exchange Notes
as contemplated in this Prospectus, the Company will receive in exchange Old
Notes in like principal amount. The form and terms of the Exchange Notes are
identical in all material respects to the form and terms of the Old Notes,
except that (i) the offering of the Exchange Notes has been registered under the
Securities Act, (ii) the Exchange Notes will not be subject to transfer
restrictions and (iii) the holders of the Exchange Notes will not be entitled to
registration or other rights under the Registration Rights Agreement including
the payment of Liquidated Damages upon failure by the Company to consummate the
Exchange Offer or the occurrence of certain other events. The Old Notes
surrendered in exchange for Exchange Notes will be retired and canceled and
cannot be reissued. Accordingly, issuance of the Exchange Notes will not result
in a change in the indebtedness of the Company.
 
                                 CAPITALIZATION
 
     The following table sets forth the capitalization of the Company as of
December 31, 1997 on an actual basis and as adjusted to give effect to the sale
of the Old Notes and the application of the net proceeds therefrom. This table
should be read in conjunction with "Use of Proceeds," "Management's Discussion
and Analysis of Financial Condition and Results of Operations," and the Combined
Financial Statements included elsewhere and incorporated by reference in this
Prospectus.
 
<TABLE>
<CAPTION>
                                                              AS OF DECEMBER 31, 1997
                                                              -----------------------
                                                               ACTUAL     AS ADJUSTED
                                                              --------    -----------
                                                                  (IN THOUSANDS)
<S>                                                           <C>         <C>
Long-term debt:
  Credit Facility...........................................  $113,000     $ 15,375(1)
  8 5/8% Senior Subordinated Notes due 2008.................        --      100,000
                                                              --------     --------
          Total long-term debt..............................   113,000      115,375
                                                              --------     --------
Stockholders' equity:
  Common Stock, $.01 par value, 23,360,903 shares issued and
     outstanding............................................       234          234
  Additional paid-in capital................................   221,907      221,907
  Retained earnings.........................................    34,046       34,046
                                                              --------     --------
          Total stockholders' equity........................   256,187      256,187
                                                              --------     --------
          Total capitalization..............................  $369,187     $371,562
                                                              ========     ========
</TABLE>
 
- ---------------
 
(1) On an as adjusted basis, the Company would have had the capacity to borrow
    an additional $119.6 million under the Credit Facility.
 
                                       32
<PAGE>   34
 
                        SELECTED COMBINED FINANCIAL DATA
 
     The selected financial data set forth below with respect to the Company's
combined statements of operations for each of the five years in the period ended
December 31, 1997 and with respect to the Company's combined balance sheets as
of December 31, 1993, 1994, 1995, 1996 and 1997 are derived from the financial
statements of the Company that have been audited by Arthur Andersen LLP,
independent public accountants. The financial data should be read in conjunction
with the "Management's Discussion and Analysis of Financial Condition and
Results of Operations" and the Company's Combined Financial Statements and Notes
thereto included elsewhere and incorporated by reference in this Prospectus.
 
<TABLE>
<CAPTION>
                                                                YEARS ENDED DECEMBER 31,
                                                --------------------------------------------------------
                                                  1993        1994        1995        1996        1997
                                                --------    --------    --------    --------    --------
                                                             (IN THOUSANDS, EXCEPT RATIOS)
<S>                                             <C>         <C>         <C>         <C>         <C>
COMBINED STATEMENT OF OPERATIONS DATA:
Revenues:
  Natural gas and oil revenues................  $ 37,462    $ 41,755    $ 39,431    $ 64,864    $116,349
  Other.......................................       799         467       1,778       1,040       1,297
                                                --------    --------    --------    --------    --------
         Total revenues.......................    38,261      42,222      41,209      65,904     117,646
Expenses:
  Lease operating.............................     4,173       4,858       5,005      10,800      14,146
  Severance tax...............................       304         486         463       1,401       4,233
  Depreciation, depletion and amortization....    23,225      25,365      21,969      33,732      59,081
  General and administrative, net.............     2,454       3,460       3,486       6,249       5,825
  Nonrecurring charge(1)......................        --          --      12,000          --          --
                                                --------    --------    --------    --------    --------
         Total operating expenses.............    30,156      34,169      42,923      52,182      83,285
Income (loss) from operations.................     8,105       8,053      (1,714)     13,722      34,361
Interest expense, net.........................     1,764       2,102       2,398       2,875         938
                                                --------    --------    --------    --------    --------
Income (loss) before income taxes.............     6,341       5,951      (4,112)     10,847      33,423
Income tax provision (benefit)................     1,790         597      (3,809)      2,205      10,173
                                                --------    --------    --------    --------    --------
Net income (loss).............................  $  4,551    $  5,354    $   (303)   $  8,642    $ 23,250
                                                ========    ========    ========    ========    ========
OTHER FINANCIAL DATA:
EBITDA(2).....................................  $ 31,330    $ 33,418    $ 32,255    $ 47,454    $ 93,442
Capital expenditures..........................    58,557      64,996      70,249     154,125     145,055
Ratio of earnings to fixed charges(3).........       3.3x        2.2x        N/M         2.2x        5.0x
</TABLE>
 
<TABLE>
<CAPTION>
                                                                   AS OF DECEMBER 31,
                                                --------------------------------------------------------
                                                  1993        1994        1995        1996        1997
                                                --------    --------    --------    --------    --------
                                                                     (IN THOUSANDS)
<S>                                             <C>         <C>         <C>         <C>         <C>
COMBINED BALANCE SHEET DATA:
Property, plant and equipment, net............  $127,911    $169,714    $216,678    $359,124    $443,738
Total assets..................................   165,031     201,678     247,496     401,285     491,391
Long-term debt................................    46,600      65,650      71,862      65,000     113,000
Stockholders' equity..........................    65,575      88,866     103,236     233,300     256,187
</TABLE>
 
- ---------------
 
(1) Represents a nonrecurring non-cash charge incurred in connection with the
    reorganization effective in February 1996. See Note 11 to the Company's
    Combined Financial Statements.
 
(2) EBITDA is defined as income (loss) from operations (before nonrecurring
    charges) plus depreciation, depletion and amortization. EBITDA should not be
    considered as an alternative to income (loss) from operations or net income
    (loss), as determined in accordance with generally accepted accounting
    principles, as a measure of the Company's operating performance or to net
    cash provided by operating, investing and financing activities, as
    determined in accordance with generally accepted accounting principles, as a
    measure of the Company's ability to meet cash needs. The Company believes
    that EBITDA is a measure commonly reported and widely used by investors and
    other interested parties as a measure of a company's operating performance
    and debt servicing ability because it assists in comparing performance on a
    consistent basis without regard to depreciation, depletion and amortization,
    which can vary significantly depending upon accounting methods (particularly
    when acquisitions are involved) or nonoperating factors (such as historical
    cost). Accordingly, this information has been disclosed herein to permit a
    more complete comparative analysis of the Company's operating performance
    relative to other companies and of the Company's debt servicing ability.
    However, EBITDA may not be comparable in all instances to other similar
    types of measures used.
 
(3) For purposes of determining the ratio of earnings to fixed charges, earnings
    are defined as income (loss) before tax plus fixed charges, adjusted to
    exclude capitalized interest. Fixed charges consist of interest expense,
    whether expensed or capitalized, and the estimated interest component of
    rent expense. Due to the $12 million nonrecurring non-cash charge incurred
    in the year ended December 31, 1995, earnings did not cover fixed charges by
    $7.0 million. If the $12 million non-cash charge is excluded, the ratio of
    earnings to fixed charges would have been 1.9x.
                                       33
<PAGE>   35
 
                      MANAGEMENT'S DISCUSSION AND ANALYSIS
                OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS
 
     The following discussion is intended to assist in an understanding of the
Company's historical financial position and results of operations for each year
of the three-year period ended December 31, 1997. The Company's historical
combined financial statements and notes thereto included elsewhere and
incorporated by reference into this Prospectus contain detailed information that
should be referred to in conjunction with the following discussion.
 
GENERAL
 
     Houston Exploration was incorporated in December 1985 to conduct certain of
the natural gas and oil exploration and development activities of Brooklyn
Union. The Company initially focused primarily on the exploration and
development of high potential prospects in the Gulf of Mexico. Effective
February 29, 1996, Brooklyn Union implemented a reorganization of its
exploration and production assets by transferring to Houston Exploration certain
onshore producing properties and developed and undeveloped acreage. Subsequent
to the reorganization, the Company has expanded its focus to include lower risk
exploitation and development drilling on the onshore properties transferred or
acquired, in addition to seeking opportunistic acquisitions both onshore and
offshore. On July 2, 1996, the Company acquired certain natural gas and oil
properties and associated pipelines located in Zapata County, Texas (the
"TransTexas Acquisition") from TransTexas. In September 1996, the Company
completed its IPO of 7,130,000 shares of its Common Stock at $15.50 per share,
resulting in net cash proceeds of approximately $101.0 million. Concurrently
with the completion of the IPO, the Company completed the acquisition of
substantially all of the natural gas and oil properties and related assets of
Soxco (the "Soxco Acquisition"). As of December 31, 1997, THEC Holdings Corp., a
wholly owned subsidiary of Brooklyn Union, owned approximately 65% of the
outstanding shares of Common Stock. At December 31, 1997, the Company had net
proved reserves of 337 Bcfe, 98% of which were natural gas and 78% of which were
classified as proved developed.
 
     The Company's revenue, profitability and future rate of growth are
substantially dependent upon prevailing prices for natural gas, oil and
condensate, which are dependent upon numerous factors beyond the Company's
control, such as economic, political and regulatory developments and competition
from other sources of energy. The energy markets have historically been highly
volatile, and future decreases in natural gas and oil prices could have a
material adverse effect on the Company's financial position, results of
operations, quantities of natural gas and oil reserves that may be economically
produced, and access to capital.
 
     The Company uses the full cost method of accounting for its investment in
natural gas and oil properties. Under the full cost method of accounting, all
costs of acquisition, exploration and development of natural gas and oil
reserves are capitalized into a "full cost pool" as incurred, and properties in
the pool are depleted and charged to operations using the unit-of-production
method based on the ratio of current production to total proved natural gas and
oil reserves. To the extent that such capitalized costs (net of accumulated
depreciation, depletion and amortization) less deferred taxes exceed the present
value (using a 10% discount rate) of estimated future net cash flows from proved
natural gas and oil reserves and the lower of cost or fair value of unproved
properties, such excess costs are charged to operations. If a writedown is
required, it would result in a charge to earnings but would not have an impact
on cash flows from operating activities. Once incurred, a writedown of oil and
gas properties is not reversible at a later date even if oil and gas prices
increase.
 
     As of December 31, 1997, the Company estimates, using prices in effect as
of such date, that the ceiling limitation imposed under full cost accounting
rules on total capitalized natural gas and oil property costs exceeded actual
capitalized costs. Natural gas prices have fluctuated substantially from prices
used in reserve valuations for the year ended December 31, 1997. Depending upon
natural gas prices and the results of the Company's drilling programs, the
Company may be required to write down the carrying value of its natural gas and
oil properties.
 
     In February 1997, the Financial Accounting Standards Board ("FASB") issued
Statement of Financial Accounting Standards ("SFAS") No. 128, "Earnings Per
Share." The statement specifies the computation, presentation, and disclosure
requirements for earnings per share ("EPS") and is designed to improve the EPS
                                       34
<PAGE>   36
 
information provided in the financial statements by simplifying the existing
computation. Primary EPS has been replaced with Basic EPS which is calculated by
dividing net income by the weighted average number of shares of common stock
outstanding during the year. No dilution for any potentially dilutive securities
is included. Fully diluted EPS is now called Diluted EPS and assumes the
conversion of all options, contingent shares and other potentially dilutive
securities. The Company adopted SFAS No. 128 in its December 31, 1997 financial
statements and has presented Diluted EPS for the years 1995 and 1996 which were
previously not required as the dilutive effect of options and contingent shares
was less than 3%. See Note 1 to the Company's Combined Financial Statements.
 
     In February 1997, the FASB issued SFAS No. 129, "Disclosure of Information
About Capital Structure," which consolidates the existing requirements to
disclose certain information about an entity's capital structure, for both
public and nonpublic entities. In June 1997, FASB issued SFAS No. 130,
"Reporting Comprehensive Income," which establishes standards for reporting and
display of comprehensive income and its components. Also issued in June of 1997
was SFAS No. 131, "Disclosures About Segments of an Enterprise and Related
Information," which specifies and revises guidelines for determining an entity's
operating and geographic segments and the type and level of financial
information about those segments to be disclosed. The Company adopted the
provisions of SFAS Nos. 129, 130 and 131 in its 1997 financial statements. The
adoption of SFAS Nos. 129, 130 and 131 did not have a material effect on its
results of operations or the calculation of net income.
 
     The Company incurs certain production gas volume imbalances in the ordinary
course of business and utilizes the entitlements method to account for its gas
imbalances. Under this method, income is recorded based on the Company's net
revenue interest in production or nominated deliveries. Deliveries in excess of
these amounts are recorded as liabilities, while under deliveries are reflected
as assets. Production imbalances are valued using market value. Management does
not believe that the Company has any material overproduced gas balances.
 
     The Company receives reimbursement for administrative and overhead expenses
incurred on the behalf of other working interest owners of properties operated
by the Company. In addition, the Company capitalizes general and administrative
costs and interest expense directly related to its acquisition, exploration and
development activities.
 
     The Company's combined historical financial statements include the
historical results of operations associated with the onshore producing
properties and developed and undeveloped acreage transferred to the Company by
Fuel Resources Inc. ("FRI"), a subsidiary of Brooklyn Union, in the February
1996 reorganization implemented by Brooklyn Union. Accordingly, the Company's
historical results of operations reflect a nonrecurring charge of $12 million
incurred in the year ended December 31, 1995 with respect to remuneration to
which certain employees of FRI were entitled for the increase in the value of
the transferred properties prior to the reorganization. See Notes 1 and 11 to
the Company's Combined Financial Statements.
 
                                       35
<PAGE>   37
 
RESULTS OF OPERATIONS
 
     The following table sets forth the Company's historical natural gas and oil
production data during the periods indicated:
 
<TABLE>
<CAPTION>
                                                          YEARS ENDED DECEMBER 31,
                                                        -----------------------------
                                                         1995       1996       1997
                                                        -------    -------    -------
<S>                                                     <C>        <C>        <C>
Production:
  Natural gas (MMcf)..................................   21,077     31,215     50,310
  Oil (MBbls).........................................      100        118        171
  Total (MMcfe).......................................   21,677     31,923     51,336
Average sales prices:
  Natural gas (per Mcf)(1)............................  $  1.79    $  2.00    $  2.25
  Oil (per Bbl).......................................    16.54      21.53      18.33
Expenses (per Mcfe):
  Lease operating.....................................  $  0.23    $  0.34    $  0.28
  Severance tax.......................................     0.02       0.04       0.08
  Depreciation, depletion and amortization............     1.01       1.06       1.15
  General and administrative, net.....................     0.16       0.20       0.11
</TABLE>
 
- ---------------
 
(1) Reflects the effects of hedging. Absent the effects of hedging, average
    realized natural gas prices would have been $1.53, $2.35 and $2.45 per Mcf
    for the years ended December 31, 1995, 1996 and 1997, respectively.
 
RECENT FINANCIAL AND OPERATING RESULTS
 
  Comparison of Years Ended December 31, 1996 and 1997
 
     Production. Houston Exploration's production increased 61% from 31,923
MMcfe in 1996 to 51,336 MMcfe in 1997. The increase in production was
attributable to added production from both the TransTexas and the Soxco
Acquisitions, which were completed during the second half of 1996, combined with
newly developed offshore production brought on-line during the second and third
quarters of 1997 and the successful development drilling and workover programs
begun in the latter half of 1996 and continuing through the fourth quarter of
1997 on the Charco Field properties acquired in the TransTexas Acquisition.
Production in the Charco Field increased 179% from approximately 33,000 Mcfe per
day in December 1996 to approximately 92,000 Mcfe per day in December 1997 as 22
development wells were successfully completed and brought on-line during 1997.
 
     Natural Gas and Oil Revenues. Natural gas and oil revenues increased 79%
from $64.9 million in 1996 to $116.3 million in 1997 as a result of the 61%
increase in production combined with a 13% increase in average realized natural
gas prices, from $2.00 per Mcf in 1996 to $2.25 per Mcf for the year ended 1997.
 
     As a result of hedging activities, the Company realized an average gas
price of $2.25 per Mcf for 1997, which was 92% of the $2.45 per Mcf that
otherwise would have been received, resulting in a $9.9 million decrease in
natural gas revenues for the year ended December 31, 1997. During 1996, the
average realized gas price was $2.00 per Mcf which was 85% of the unhedged
average gas price of $2.35, resulting in a decrease in natural gas revenues of
$11.1 million for the year ended 1996.
 
     Lease Operating Expenses and Severance Tax. Lease operating expenses
increased 31% from $10.8 million in 1996 to $14.1 million in 1997. On an Mcfe
basis, lease operating expenses decreased from $0.34 in 1996 to $0.28 in 1997.
The increase in lease operating expenses during 1997 is primarily attributable
to properties acquired in the TransTexas Acquisition and the significant
expansion of operations in the Charco Field combined with the effects of an
industry-wide increase in operating costs. The decrease in the lease operating
expenses per Mcfe resulted from the substantial increase in production during
1997. Severance tax, which is a function of volume and revenues generated from
onshore production, increased 202% from $1.4 million, or $0.04 per Mcfe, in 1996
to $4.2 million, or $0.08 per Mcfe, in 1997. The increase in severance tax is
due to the
 
                                       36
<PAGE>   38
 
increase in production from the onshore Charco Field properties combined with
higher gas prices in 1997 as compared to 1996.
 
     Depreciation, Depletion and Amortization. Depreciation, depletion and
amortization expense increased 75% from $33.7 million in 1996 to $59.1 million
in 1997. Depreciation, depletion and amortization expense per Mcfe increased 9%
from $1.06 in 1996 to $1.15 in 1997. The increase in depreciation, depletion and
amortization expense was a result of the increased production from acquired as
well as newly developed properties combined with an increased depletion rate.
The increase in the depletion rate is attributable partly to the industry-wide
increase in costs of drilling goods and services, platform and facilities
construction combined with a relatively modest increase in reserves given the
increased capital expenditures from the Company's exploration and development
activities during 1997.
 
     General and Administrative Expenses. General and administrative expenses,
net of overhead reimbursements received from other working interest owners of
$1.0 million and $0.9 million, in 1996 and 1997, respectively, decreased 7% from
$6.2 million in 1996 to $5.8 million in 1997. After excluding the one-time
charge of $0.8 million taken in September 1996 in conjunction with the IPO for
the buyout and termination of stock options granted to certain officers and
directors of Brooklyn Union, general and administrative expense increased 7%
from $5.4 million in 1996 to $5.8 million in 1997. The increase in general and
administrative expense reflects the overall growth and expansion of the Company
and its operations since the second half of 1996 and continuing through the end
of 1997. The Company capitalized general and administrative expenses directly
related to oil and gas exploration and development activities of $5.3 million
and $7.2 million, respectively, in 1996 and 1997. The increase in capitalized
general and administrative expense directly corresponds with the growth of the
Company's technical workforce and the implementation of an incentive
compensation plan. On an Mcfe basis, general and administrative expenses
decreased 45% from $0.20 in 1996 to $0.11 in 1997. The lower rate per Mcfe
during 1997 reflects the increase in the Company's production.
 
     Income Tax Provision. The provision for income taxes increased from an
expense of $2.2 million in 1996 to an expense of $10.2 million in 1997 due to
the increase in pretax income offset by the benefit received from Section 29 tax
credits.
 
     Operating Income and Net Income. Operating income increased 151% to $34.4
million in 1997 from $13.7 million in 1996. Net income increased 171% from $8.6
million in 1996 to $23.3 million in 1997. The significant increase in operating
income and net income was attributable primarily to higher production volumes
and higher net realized natural gas prices combined with lower lease operating
expenses.
 
  Comparison of Years Ended December 31, 1995 and 1996
 
     Production. Houston Exploration's production increased 47% from 21,677
MMcfe in 1995 to 31,923 MMcfe in 1996. The 1996 production increase is
attributed to commencement of production from newly developed offshore
properties during the first half of the year and the Company's two significant
acquisitions during the second half of the year: (i) the TransTexas Acquisition,
which was completed on July 2, 1996, and (ii) the Soxco Acquisition, which was
completed on September 25, 1996 concurrently with the closing of the IPO.
 
     Natural Gas and Oil Revenues. Natural gas and oil revenues increased 65%
from $39.4 million in 1995 to $64.9 million in 1996 as a result of the 47%
increase in production and an increase in average realized natural gas prices of
12% from $1.79 per Mcf in 1995 to $2.00 Mcf in 1996.
 
     As a result of hedging activities, the Company realized an average gas
price of $2.00 per Mcf for 1996, compared to an average price of $2.35 per Mcf
that otherwise would have been received, resulting in a $11.1 million decrease
in natural gas revenues for the year ended December 31, 1996. During 1995, the
average realized gas price was $1.79 per Mcf compared to an unhedged average gas
price of $1.53, resulting in an increase in natural gas revenues of $5.6 million
for the year ended December 31, 1995.
 
     Lease Operating Expenses and Severance Tax. Lease operating expenses
increased 116% from $5.0 million in 1995 to $10.8 million in 1996. On an Mcfe
basis, lease operating expenses increased from $0.23 in 1995 to $0.34 in 1996.
Of the $5.8 million increase in lease operating expenses during 1996, $2.2
million relates
                                       37
<PAGE>   39
 
directly to properties acquired in the TransTexas Acquisition at the beginning
of the third quarter and includes certain one-time expenses incurred in taking
over operations of these properties, and the remaining $3.6 million reflects
higher initial operating costs associated with bringing new facilities and wells
on-line. Severance tax, which is a function of volume and revenues generated
from onshore production, increased 180% from $0.5 million, or $0.02 per Mcfe, in
1995 to $1.4 million, or $0.04 per Mcfe, in 1996. The increase in severance tax
resulted from the addition of production from the onshore Charco Field
properties combined with an increase in net realized natural gas prices during
the fourth quarter of 1996.
 
     Depreciation, Depletion and Amortization. Depreciation, depletion and
amortization expense increased 53% from $22.0 million in 1995 to $33.7 million
in 1996. The increase was attributable to the increase in production during
1996. Depreciation, depletion and amortization expense per Mcfe increased from
$1.01 in 1995 to $1.06 in 1996, primarily as a result of exploratory drilling
which did not add significant new reserves during the period.
 
     General and Administrative Expenses. General and administrative expenses,
net of overhead reimbursements received from other working interest owners of
$1.2 million and $1.0 million for 1995 and 1996, respectively, increased 77%
from $3.5 million in 1995 to $6.2 million in 1996. The Company capitalized
general and administrative expenses directly related to oil and gas exploration
and development activities of $4.1 million and $5.3 million, respectively, in
1995 and 1996. The increase in net general and administrative expenses during
1996 is a result of certain one-time expenses incurred in conjunction with the
combination of offshore and onshore operations and an $0.8 million charge taken
in conjunction with the IPO for the buyout and termination of options to
purchase Common Stock granted to certain officers and directors of Brooklyn
Union under the Company's 1994 Incentive Plan. On an Mcfe basis, general and
administrative expenses increased from $0.16 in 1995 to $0.20 in 1996, or $0.17
per Mcfe excluding the $0.8 million buyout of the options issued under the 1994
Incentive Plan.
 
     Nonrecurring Charge. During 1995, the Company incurred a $12.0 million
nonrecurring charge to reflect the amount of remuneration paid to former
employees of FRI. During 1996 the Company did not incur additional charges
related to the remuneration paid to former FRI employees. See "-- General" and
Note 11 to the Company's Combined Financial Statements.
 
     Income Tax Provision. Income tax expense increased from a benefit of $3.8
million in 1995 to an expense of $2.2 million in 1996. Included in the provision
for 1995 was a credit of $4.2 million related to the $12.0 million nonrecurring
charge. For 1996, the primary difference between the Company's statutory tax
rate of 35% and its effective rate of 20% was due to the utilization of Section
29 credits received for specific onshore properties.
 
     Net Income. The Company's net income increased from a loss of $0.3 million
in 1995 to net income of $8.6 million in 1996. Excluding the effects of the
$12.0 million charge ($7.8 million net of tax), the Company's net income
increased 15% from $7.5 million in 1995 to $8.6 million in 1996. The increase in
net income resulted from increased production from newly developed properties
and production from properties acquired in the TransTexas and Soxco
Acquisitions, combined with an increase in realized natural gas prices. Both
lease operating and general and administrative expenses increased from the prior
year due to certain one-time charges and interest expense reflects third quarter
borrowings, which were repaid with proceeds from the IPO.
 
LIQUIDITY AND CAPITAL RESOURCES
 
     The Company has historically funded its operations, acquisitions, capital
expenditures and working capital requirements from cash flows from operations,
bank borrowings and, prior to the IPO, capital contributions from Brooklyn
Union. See also "Risk Factors -- Effects of Leverage."
 
     As of December 31, 1997, the Company had a working capital deficit of $5.4
million (which includes the accrued liability of $8.8 million for the Soxco
minimum deferred purchase price which is payable in shares of Common Stock
during the first quarter of 1998) and $15.4 million of available borrowing base
under its Credit Facility. Net cash provided by operating activities for the
year ended December 31, 1997 was $97.3 million
 
                                       38
<PAGE>   40
 
compared to $54.1 million for the year ended December 31, 1996. The Company's
cash position was increased during the year ended December 31, 1997 by
borrowings of $79.0 million under the Company's Credit Facility. Funds used in
investing and financing activities consisted of $145.1 million for investments
in property and equipment and principal payments of $31.0 million on long-term
borrowing under the Credit Facility. As a result of these activities, cash and
cash equivalents increased $1.9 million from $2.8 million at December 31, 1996
to $4.7 million at December 31, 1997.
 
     Over the past three years, the Company has spent $390 million (including
$96.9 million expended on the TransTexas and the Soxco acquisitions) to add 294
Bcfe of net proved reserves, representing a finding and development cost of
$1.33 per Mcfe. The Company's primary sources of funds for each of the past
three years are reflected in the following table:
 
<TABLE>
<CAPTION>
                                                          YEARS ENDED DECEMBER 31,
                                                       ------------------------------
                                                        1995        1996       1997
                                                       -------    --------    -------
                                                               (IN THOUSANDS)
<S>                                                    <C>        <C>         <C>
Net cash provided by operating activities............  $55,778    $ 54,065    $97,292
Net borrowings (repayments) under Credit Facility....    6,212      (6,862)    48,000
Proceeds from sale of common stock...................       --     101,014        297
Capital contributions from Brooklyn Union............    6,873       6,342         --
</TABLE>
 
     The Company's natural gas and oil capital expenditures for each of the past
three years are reflected in the following table:
 
<TABLE>
<CAPTION>
                                                         YEARS ENDED DECEMBER 31,
                                                      -------------------------------
                                                       1995        1996        1997
                                                      -------    --------    --------
                                                              (IN THOUSANDS)
<S>                                                   <C>        <C>         <C>
OFFSHORE:
  Acquisitions of properties........................  $18,236    $ 58,578    $ 30,700
  Development.......................................   32,228      25,399      19,826
  Exploration.......................................    6,355      27,398      42,219
                                                      -------    --------    --------
                                                       56,819     111,375      92,745
ONSHORE:
  Acquisitions of properties........................  $ 2,803    $ 59,513    $  9,920
  Development.......................................    8,935       5,844      39,418
  Exploration.......................................      869          --       1,900
                                                      -------    --------    --------
                                                       12,607      65,357      51,238
                                                      -------    --------    --------
          Total.....................................  $69,426    $176,732    $143,983
                                                      =======    ========    ========
</TABLE>
 
     The Company's capital expenditure budget for 1998 of $100 million includes
$55 million and $45 million, respectively, for exploration and development.
These amounts include development costs associated with recently acquired
properties and amounts that are contingent upon drilling success. The Company
will continue to evaluate its capital spending plans through the year. No
significant abandonment or dismantlement costs are anticipated through 1998.
Actual levels of capital expenditures may vary significantly due to a variety of
factors, including drilling results, natural gas prices, industry conditions and
outlook and future acquisitions of properties. The Company believes cash flows
from operations and borrowings under its Credit Facility will be sufficient to
fund these expenditures. The Company will continue to selectively seek
acquisition opportunities for proved reserves with substantial exploration and
development potential both offshore and onshore. The size and timing of capital
requirements for acquisitions is inherently unpredictable. The Company expects
to fund exploration and development through a combination of cash flow from
operations, borrowings under its Credit Facility, or the issuance of equity or
debt securities.
 
     If the Pending Acquisition is completed, the Company intends to pay the
estimated $54.9 million purchase price of the Pending Acquisition using funds
borrowed under the Credit Facility. The Company does not presently intend to
increase its capital expenditure budget if the Pending Acquisition is completed.
 
                                       39
<PAGE>   41
 
     The Company has entered into the Credit Facility with a syndicate of
lenders led by Chase Bank of Texas, National Association ("Chase") which
provides a maximum loan amount of $150 million, subject to borrowing base
limitations, on a revolving basis. The Credit Facility had a borrowing base of
$130 million prior to the sale of the Old Notes, which was reduced to $115
million upon completion of the sale of the Old Notes and subsequently increased
to $135 million. At December 31, 1997, $113 million was borrowed and $1.6
million was committed under outstanding letter of credit obligations. The Credit
Facility matures on July 1, 2000. Advances under the Credit Facility bear
interest, at the Company's election at (i) a fluctuating rate ("Base Rate")
equal to the higher of the Federal Funds Rate plus 0.5% or Chase's prime rate or
(ii) a fixed rate ("Fixed Rate") equal to a quoted LIBOR rate plus a margin
between 0.375% and 1.125% depending on the amount outstanding under the Credit
Facility. Interest is due at calendar quarters for Base Rate loans and at the
earlier of maturity or three months from the date of the loan for Fixed Rate
loans. The Credit Facility contains covenants of the Company, including certain
restrictions on liens and financial covenants which require the Company to,
among other things, maintain (i) an interest coverage ratio of 2.5 to 1.0 of
earnings before interest, taxes and depreciation to cash interest ("EBITDA") and
(ii) a total debt to capitalization ratio of less than 60%. The Credit Facility
also restricts the Company's ability to purchase or redeem its capital stock or
to pledge its oil and gas properties or other assets. As of December 31, 1997
the Company was in compliance with all Credit Facility covenants. The borrowing
base under the Credit Facility is determined by Chase in its discretion in
accordance with Chase's then current standards and practices for similar oil and
gas loans taking into account such factors as Chase deems appropriate.
 
     For a description of certain bonding requirements related to offshore
production proposed by the Minerals Management Service, see
"Business -- Environmental Matters."
 
     The Company utilizes derivative commodity instruments to hedge future sales
prices on a portion of its natural gas production to achieve a more predictable
cash flow, as well as to reduce its exposure to adverse price fluctuations of
natural gas. While the use of these hedging arrangements limits the downside
risk of adverse price movements, they may limit future revenues from favorable
price movements. The use of hedging transactions also involves the risk that the
counterparties will be unable to meet the financial terms of such transactions.
Hedging instruments used are swaps, collars and options, and are generally
placed with major financial institutions that the Company believes are minimal
credit risks. The Company accounts for these transactions as hedging activities
and, accordingly, gains or losses are included in natural gas and oil revenues
in the period the hedged production occurs. Unrealized gains and losses on these
contracts, if any, are deferred and offset in the balance sheet against the
related settlement amounts.
 
     As of December 31, 1997, the Company had entered into commodity price
hedging contracts with respect to its gas production as listed below. Natural
gas production during the month of December 1997 was 5,419 MMcf (5,570 MMMBtu).
 
<TABLE>
<CAPTION>
                          FIXED PRICE SWAPS              COLLARS                       OPTIONS
                         --------------------   --------------------------   ----------------------------
                                                                NYMEX
                                                              CONTRACT
                                      NYMEX                     PRICE                   NYMEX
                          VOLUME     CONTRACT    VOLUME    ---------------    VOLUME    STRIKE
        PERIOD           (MMMBTU)     PRICE     (MMMBTU)   FLOOR   CEILING   (MMMBTU)   PRICE    PUT/CALL
        ------           ---------   --------   --------   -----   -------   --------   ------   --------
<S>                      <C>         <C>        <C>        <C>     <C>       <C>        <C>      <C>
January 1998...........     355        $2.07     1,860     $2.73    $3.88      155      $2.01       Put
February 1998..........     340        $2.07     1,120     $2.65    $3.16      140      $2.01       Put
February 1998..........                                                        560      $3.50      Call
March 1998.............     355        $2.07       930     $2.25    $2.75      155      $2.01       Put
</TABLE>
 
                                       40
<PAGE>   42
 
     Subsequent to December 31, 1997, the Company entered into additional
commodity price hedging contracts as listed below (as of April 14, 1998):
 
<TABLE>
<CAPTION>
                          FIXED PRICE SWAPS              COLLARS                       OPTIONS
                         --------------------   --------------------------   ----------------------------
                                                                NYMEX
                                                              CONTRACT
                                      NYMEX                     PRICE                   NYMEX
                          VOLUME     CONTRACT    VOLUME    ---------------    VOLUME    STRIKE
        PERIOD           (MMMBTU)     PRICE     (MMMBTU)   FLOOR   CEILING   (MMMBTU)   PRICE    PUT/CALL
        ------           ---------   --------   --------   -----   -------   --------   ------   --------
<S>                      <C>         <C>        <C>        <C>     <C>       <C>        <C>      <C>
March 1998.............      --           --       930     $2.20    $2.58       --         --        --
April 1998.............      --           --       900     $2.20    $2.58       --         --        --
May 1998...............      --           --     3,410     $2.26    $2.70       --         --        --
June 1998..............      --           --     3,300     $2.26    $2.70       --         --        --
July 1998..............      --           --     2,790     $2.25    $2.70       --         --        --
August 1998............      --           --     2,790     $2.25    $2.70       --         --        --
September 1998.........      --           --     2,700     $2.25    $2.70       --         --        --
October 1998...........      --           --       930     $2.20    $2.50       --         --        --
</TABLE>
 
     As of April 30, 1998, the Company had no commodity hedging contracts
extending beyond October 1998. The Company has entered into basis swaps with
respect to more than 50% of its indicated NYMEX hedged volume.
 
     These hedging transactions are settled based upon the average of the
reported settlement prices on the New York Mercantile Exchange (the "NYMEX") for
the last three trading days of a particular contract month (the "settlement
price"). With respect to any particular swap transaction, the counterparty is
required to make a payment to the Company in the event that the settlement price
for any settlement period is less than the swap price for such transaction, and
the Company is required to make payment to the counterparty in the event that
the settlement price for any settlement period is greater than the swap price
for such transaction. For any particular collar transaction, the counterparty is
required to make a payment to the Company if the settlement price for any
settlement period is below the floor price for such transaction, and the Company
is required to make payment to the counterparty if the settlement price for any
settlement period is above the ceiling price for such transaction. For any
particular floor transaction, the counterparty is required to make a payment to
the Company if the settlement price for any settlement period is below the floor
price for such transaction. The Company is not required to make any payment in
connection with a floor transaction. For option contracts, the Company has the
option, but not the obligation, to buy contracts at the strike price up to the
day before the last trading day for that NYMEX contract.
 
     The Company periodically enters into basis swaps (either as part of a
particular hedging transaction or separately) tied to a particular NYMEX-based
transaction to eliminate basis risk. Because substantially all of the Company's
natural gas production is sold under spot contracts, that have historically
correlated with the swap price, the Company believes that it has no material
basis risk with respect to gas swaps that are not coupled with basis swaps.
 
                                       41
<PAGE>   43
 
                                    BUSINESS
 
OVERVIEW
 
     Houston Exploration is an independent natural gas and oil company engaged
in the exploration, development, exploitation and acquisition of domestic
natural gas and oil properties. The Company's offshore properties are located
primarily in the shallow waters (up to 600 feet) of the Gulf of Mexico, and its
onshore properties are located in South Texas, the Arkoma Basin, East Texas and
West Virginia. The Company has utilized its geological and geophysical expertise
to grow its reserve base through a combination of high potential exploratory
drilling in the Gulf of Mexico and lower risk, high impact exploitation and
development drilling onshore. The Company believes that the lower risk projects
and more stable production associated with its onshore properties complement its
high potential exploratory prospects in the Gulf of Mexico by balancing risk and
reducing volatility.
 
     The Company has achieved significant growth in net proved reserves,
production, revenues and EBITDA over the past five years. The Company has
increased net proved reserves at a compound annual rate of 30% from 92 Bcfe at
December 31, 1992 to 337 Bcfe at December 31, 1997. During this period, annual
production increased at a compound annual rate of 30% from 14 Bcfe in 1992 to 51
Bcfe in 1997. Average daily production during the month of December 1997 was 179
MMcfe per day. The Company's oil and gas revenues and EBITDA have increased from
$22 million in 1992 to $116 million in 1997, and its EBITDA increased from $17
million to $93 million in the same period. At December 31, 1997, Houston
Exploration reported net proved reserves of 337 Bcfe with a discounted present
value of cash flows before income taxes ("PV-10%") of $377 million.
 
     The Company believes that its primary strengths are its high quality
reserves, its substantial inventory of high potential exploration, exploitation
and development opportunities, its expertise in generating new prospects, its
geographic focus and its low-cost operating structure. Approximately 98% of the
Company's net proved reserves at December 31, 1997 were natural gas and
approximately 78% were classified as proved developed. The Company operates over
90% of its production.
 
     The geographic focus of the Company's operations in the Gulf of Mexico and
core onshore areas enables it to manage a large asset base with a relatively
small number of employees and to add and operate production at relatively low
incremental costs. The Company achieved lease operating expenses (excluding
severance taxes) of $0.28 per Mcfe of production and net general and
administrative expenses of $0.11 per Mcfe of production for the year ended
December 31, 1997. The Company believes that these expense levels are among the
lowest within its peer group.
 
BUSINESS STRATEGY
 
     The Company's strategy is to continue to increase its reserves, production
and cash flow by pursuing internally generated exploration prospects, primarily
in the Gulf of Mexico, by conducting development and exploitation drilling on
its onshore and offshore properties and by making selective opportunistic
acquisitions. Over the past five years, the Company has added 400 Bcfe of net
proved reserves through exploration, acquisitions and exploitation and
development. During this period, the Company has produced a total of 151 Bcfe,
and total net proved reserves added due to extensions, discoveries and revisions
were approximately 168% of cumulative production. Total net proved reserves
added during this period including acquisitions were approximately 265% of
cumulative production. During 1997, the Company increased production by more
than 60%, from 32 Bcfe in 1996 to 51 Bcfe in 1997. The Company focuses on the
following elements in implementing this strategy:
 
  High Potential Exploratory and Development Drilling in the Gulf of Mexico
 
     The Company plans to drill approximately 15 exploratory wells in the Gulf
of Mexico in 1998, the successful completion of any one of which could
substantially increase the Company's reserves. Over the past five years, the
Company has drilled 20 successful exploratory wells and 19 successful
development wells in the Gulf of Mexico, representing a historical success rate
of 74%. The Company believes it has assembled a four
                                       42
<PAGE>   44
 
year inventory of exploration and development drilling opportunities in the Gulf
of Mexico, principally in shallow waters. The Company holds interests in 79
lease blocks, representing 394,093 gross (292,837 net) acres, in federal and
state waters in the Gulf of Mexico, of which 28 have current operations. The
Company has a 100% working interest in 38 of these lease blocks and a 50% or
greater working interest in 22 other lease blocks. The Company anticipates that
approximately $68 million of its $100 million 1998 capital expenditure budget
(excluding acquisitions) will be spent on offshore projects. In addition, the
Company intends to continue its participation in federal lease sales and to
actively pursue attractive farm-in opportunities as they become available. The
Company's management believes that the Gulf of Mexico area remains attractive
for future exploration and development activities due to the availability of
geologic data, remaining reserve potential and the infrastructure of gathering
systems, pipelines, platforms and providers of drilling services and equipment.
Based on 1997 annual production, the Company's offshore reserves have a reserve
to production ratio of 5.4 years. During December 1997, average net production
from the Company's Gulf of Mexico properties was approximately 62 MMcfe per day.
 
  Lower Risk, High Impact Exploitation and Development Drilling Onshore
 
     The Company owns significant onshore natural gas and oil properties in
South Texas, the Arkoma Basin of Oklahoma and Arkansas, East Texas and West
Virginia, accounting for approximately 65% of its net proved reserves at
December 31, 1997. Complementing the Company's offshore properties, the
Company's onshore properties are characterized by relatively longer reserve
lives and more predictable production. Over the past five years, the Company has
drilled or participated in the drilling of 63 successful development wells and
six successful exploratory wells onshore representing a historical drilling
success rate of 76%. One example of the successful implementation of the
Company's onshore strategy is in the Charco Field in South Texas, where the
Company has increased net production from an average of 38 MMcfe per day in July
1996, immediately following its acquisition of such properties, to an average 92
MMcfe per day in December 1997. During 1997, the Company produced 20 Bcfe, net
to the Company's interest, from the Charco Field and added 40 Bcfe in net proved
reserves. The Company has identified an extensive inventory of more than 100
potential onshore drilling locations, of which approximately 70 are located in
the Charco Field. The Company anticipates that approximately $32 million of its
$100 million 1998 capital expenditure budget (excluding acquisitions) will be
spent on onshore projects, including the drilling of approximately 25 wells.
Based on 1997 annual production, the Company's onshore reserves have a reserve
to production ratio of 7.4 years. During December 1997, average net production
from the Company's onshore properties was approximately 117 MMcfe per day.
 
  Opportunistic Acquisitions
 
     The Company's primary strategy to grow its reserves through the drillbit is
supplemented by the Company's continuing pursuit of opportunistic acquisitions
of properties with unexploited reserve potential. The Company targets properties
(i) that it can operate, (ii) that are either in the Gulf of Mexico or onshore
in existing core operating areas or in new geographic areas in which the Company
believes it can establish a substantial concentration of properties and
operations, and (iii) that provide a base for further exploration and
development. The Company has a successful track record of building its reserves
through opportunistic acquisitions onshore and in the Gulf of Mexico and
successfully exploiting those reserves. In particular, the Company has drilled
25 successful wells (74% success rate) in the Charco Field since acquiring its
properties in the field in July 1996. See "Prospectus Summary -- Recent
Acquisition."
 
  High Percentage of Operated Properties
 
     The Company seeks to operate properties in which it has a significant
ownership interest. By operating these properties, the Company can manage
production performance while controlling operating expenses and the timing and
amount of capital expenditures. Properties operated by the Company account for
approximately 90% of its Gulf of Mexico production and approximately 95% of its
onshore production. The Company currently has two offshore jackup rigs and two
land rigs under long-term contracts, which allow the Company to manage the
timing of the drilling of its wells. The Company also pursues cost savings
through the use of outside contractors for much of its offshore field operations
activities. As a result of these and other factors, the
 
                                       43
<PAGE>   45
 
Company achieved lease operating expense (excluding severance taxes) of $0.28
per Mcfe of production and net general and administrative expense of $0.11 per
Mcfe of production for the year ended December 31, 1997.
 
  Use of Advanced Technology for In-House Prospect Generation
 
     The Company generates virtually all of its exploration prospects utilizing
in-house geological and geophysical expertise. The Company uses advanced
technology, including 3-D seismic and in-house computer-aided exploration
technology, to reduce risks, lower costs and prioritize drilling prospects. The
Company has acquired approximately 2,400 square miles of 3-D seismic data,
including 3-D seismic surveys on 65 of its offshore lease blocks and on possible
lease and acquisition prospects, and 73,500 linear miles of offshore 2-D seismic
data. Since the acquisition of its Charco Field properties in 1996, the Company
has purchased and commenced interpretation of 3-D seismic data covering 148
square miles of the field. In 1998, the Company anticipates the acquisition of
30 square miles of 3-D seismic data on its recently acquired East Texas acreage.
The Company has 13 geologists/geophysicists with average industry experience of
approximately 28 years and 10 geophysical workstations for use in interpreting
3-D seismic data. The availability of 3-D seismic data for Gulf of Mexico
properties at reasonable costs has enabled the Company to identify exploration
and development prospects in the Company's existing inventory of properties and
to define possible lease and acquisition prospects.
 
  Geographically Focused Operations
 
     Focusing drilling activities on properties in relatively concentrated
offshore and onshore areas permits the Company to utilize its base of
geological, engineering, exploration and production experience in the regions.
The Company currently operates in five areas of geographic concentration -- the
Gulf of Mexico, South Texas, the Arkoma Basin, East Texas, and West
Virginia -- and continues to evaluate and may add additional core areas in the
future. The Company recently completed an acquisition that adds a new core area
of operations onshore in South Louisiana. See "Prospectus Summary -- Recent
Acquisition." The geographic focus of the Company's operations allows it to
manage a large asset base with a relatively small number of employees and
enables the Company to add production at relatively low incremental costs. For
example, in the Charco Field, the Company has reduced lease operating expense
(excluding severance taxes) by 50%, from $0.38 per Mcfe for the six month period
beginning on July 1, 1996, when the Company acquired its Charco Field
properties, and ending December 31, 1996 to $0.19 per Mcfe for the six month
period ended December 31, 1997.
 
     The following table sets forth information regarding the Company's reserves
associated with its properties in the Gulf of Mexico, the Charco Field in South
Texas and the Company's other onshore properties:
 
<TABLE>
<CAPTION>
                                                                NET PROVED RESERVES
                                                               AT DECEMBER 31, 1997
                                             PERCENT OF    -----------------------------
                                               TOTAL         GAS        OIL       TOTAL
                                              RESERVES     (MMCF)     (MBBLS)    (MMCFE)
                                             ----------    -------    -------    -------
<S>                                          <C>           <C>        <C>        <C>
Gulf of Mexico.............................     35%        112,739       869     117,953
Charco Field...............................     38%        126,575        50     126,875
Other Onshore..............................     27%         91,287       158      92,235
                                                           -------     -----     -------
                                                           330,601     1,077     337,063
                                                           =======     =====     =======
</TABLE>
 
GULF OF MEXICO PROPERTIES
 
     The Company holds interests in 79 offshore blocks, of which 28 have current
operations, and operates 18 of these blocks, accounting for approximately 90% of
the Company's offshore production. The following table lists the Company's
average working interest, net proved reserves and the operator for the Company's
eight
 
                                       44
<PAGE>   46
 
largest offshore properties as of December 31, 1997, representing 77% of the
Company's Gulf of Mexico proved reserves and 65% of its offshore production:
 
<TABLE>
<CAPTION>
                                             NET PROVED RESERVES AT DECEMBER 31, 1997
                                       ----------------------------------------------------
                                                                     AVERAGE
                                         GAS       OIL      TOTAL    WORKING
                FIELD                  (MMCF)    (MBBLS)   (MMCFE)   INTEREST    OPERATOR
                -----                  -------   -------   -------   --------   -----------
<S>                                    <C>       <C>       <C>       <C>        <C>
East Cameron Blocks 82/83............   18,526     140     19,366      97.8%    Company
Mustang Island Blocks 858/868........   18,343     329     20,317      79.0%    Company
West Cameron Blocks 76/77/60/61
  Unit...............................   10,826      73     11,264      10.9%    Third Party
Matagorda Island Block 651...........   10,586       6     10,622      79.6%    Company
High Island Block 38.................    7,655      79      8,129      40.0%    Third Party
Mustang Island Block 807.............    7,892      23      8,030     100.0%    Company
Mustang Island Block 759.............    6,591      15      6,681      25.0%    Third Party
Mustang Island Block 785.............    5,914      --      5,914      72.5%    Company
All Other Gulf of Mexico (10
  fields)............................   26,406     204     27,630
                                       -------     ---     -------
          Total Gulf of Mexico.......  112,739     869     117,953
                                       =======     ===     =======
</TABLE>
 
     During 1997, the Company drilled six successful exploratory wells and one
successful development well on its Gulf of Mexico properties. During this same
period, the Company drilled three exploratory wells and one development well
that were not successful. Capital spending associated with the Company's Gulf of
Mexico properties during 1997 was $92.7 million, including $42.2 million for
exploratory drilling, $19.8 million for development drilling and $30.7 million
for leasehold and lease acquisitions. During 1997, the Company acquired one
producing property, Mustang Island 868, for $2.6 million.
 
     During 1998, the Company intends to focus on exploratory drilling in the
Gulf of Mexico and plans to drill approximately 15 exploratory wells, along with
limited development drilling. The Company's planned exploratory projects are
located in East Cameron Blocks 82/83, West Cameron Block 174, Mustang Island
Blocks A-113/114 and 138/139, High Island Block 115, South Timbalier Block 318
and Brazos Block A-40. As of April 14, 1998, the Company was drilling or
participating in the drilling of exploratory wells on East Cameron Block 83 and
Galveston Island Block 144. The Company drilled one unsuccessful exploratory
well in the first quarter of 1998. The following is a summary description of the
Company's exploration and development activity during 1997. The Company is the
operator of each of these properties except for High Island Block 38 and Eugene
Island Block 64.
 
     Mustang Island Blocks 858/868. The Company holds an 82.5% working interest
in Mustang Island Block 858 and a 65% working interest in Mustang Island Block
868. The property has three producing wells, the first of which commenced
production in July 1996. During November 1997, the Company completed the
workover of one well and commenced drilling on a development well and an
exploratory well on the property. At December 31, 1997, the Company was
continuing to drill both wells toward targeted objectives at depths between
14,000 and 15,000 feet; the exploratory well was logged and determined to be
unproductive in January 1998, and the development well encountered mechanical
difficulties and was plugged and abandoned in late February 1998. During
December 1997, the block produced at an average rate of 6,100 Mcfe/d, net to the
Company, which reflects production downtime due to drilling rigs on location. In
December 1997, the Company completed the purchase of a 65% working interest in
Mustang Island Block 868, a neighboring block which includes the platform and
facilities used for production from Mustang Island Block 858. The Company
believes the acquisition will enable it to control and improve the efficiency of
operations for the two properties. The Company owns substantial leasehold
interests in adjacent blocks and is planning additional exploratory and
development drilling during 1998.
 
     East Cameron Blocks 82/83. The Company holds an average working interest of
97.8% in East Cameron Blocks 82 and 83. The property currently has one producing
platform on Block 82 and two satellite platforms. In February 1997, the Company
began drilling an exploratory well on Block 83, which was successfully
 
                                       45
<PAGE>   47
 
completed in June 1997 after experiencing a period of uncontrolled gas flow.
During December 1997, the production from the combined platforms averaged 12,200
Mcfe/d, net to the Company.
 
     Mustang Island Block 807. The Company holds a 100% working interest in
Mustang Island Block 807. The Block has one well, the initial discovery well,
which during December 1997 produced at an average of 4,500 Mcfe/d, net to the
Company. Platform construction was completed during the first months of 1997 and
initial production began in June 1997.
 
     Galveston Island Blocks 252/272. The Company holds an average working
interest of 43.9% in Galveston Island Block 252/272. The property has two
platforms and one satellite platform at Galveston Island Block 272. In late
February 1997, the Company began drilling an exploratory well which was
successfully completed and brought on-line in May 1997. During December 1997,
the platforms were producing at a combined rate averaging 4,100 Mcfe/d, net to
the Company.
 
     East Cameron Block 185. The Company acquired a 100% working interest in
East Cameron Block 185 in March 1996. The Company successfully drilled and
completed an exploratory well during the third quarter of 1997, and completed
the workover of another well on the property. During December 1997, production
averaged 5,300 Mcfe/d, net to the Company.
 
     Mustang Island Block 738. The Company holds a 49.9% working interest in
Mustang Island Block 738. The property has two producing wells which came
on-line in March 1996. During the fourth quarter of 1997, the Company drilled an
additional development well which was unsuccessful. During December 1997,
production averaged 1,100 Mcfe/d, net to the Company.
 
     High Island Block 38. The Company holds a 40% working interest in High
Island Block 38. The Company participated in the successful drilling of an
exploratory well that was completed in the third quarter of 1997. Production
facilities were completed in January 1998 and initial production began in late
January at an initial flow rate between 4,400 and 7,300 Mcfe/d, net to the
Company.
 
     Eugene Island Block 64. The Company acquired a 25% working interest in
Eugene Island Block 64 and participated in the drilling of an exploratory well
which was successfully completed in November 1997. Production facilities were
completed and initial production commenced in the first quarter of 1998.
 
ONSHORE PROPERTIES
 
     The Company also owns significant onshore natural gas and oil properties in
South Texas, the Arkoma Basin of Oklahoma and Arkansas, East Texas and West
Virginia. These properties represent interests in 1,104 gross (732 net) wells,
approximately 95% of which the Company is the operator of record, and 166,463
gross (126,611 net) acres.
 
     The following table lists the Company's average working interest and net
proved reserves for the Company's core onshore areas of operation as of December
31, 1997, representing 99% of the Company's onshore reserves:
 
<TABLE>
<CAPTION>
                                                             NET PROVED RESERVES AT
                                                                DECEMBER 31, 1997
                                              AVERAGE     -----------------------------
                                              WORKING       GAS        OIL       TOTAL
                   FIELD                      INTEREST    (MMCF)     (MBBLS)    (MMCFE)
                   -----                      --------    -------    -------    -------
<S>                                           <C>         <C>        <C>        <C>
Charco Field (South Texas)..................    95%       126,575      50       126,875
Chismville/Massard Field (Arkansas).........    73%        48,079      --        48,079
Wilburton, Panola and Surrounding Fields
  (Oklahoma)................................    23%         7,666      --         7,666
Willow Springs and Surrounding Fields (East
  Texas)....................................    53%         9,731      91        10,277
Appalachian Area (West Virginia)............    60%        25,811      67        26,213
</TABLE>
 
     During 1997, the Company participated in the drilling of 33 successful
development wells and two successful exploratory wells on its onshore
properties. During this same period, the Company participated in
 
                                       46
<PAGE>   48
 
the drilling of eight development wells and two exploratory wells that were not
successful. Capital spending associated with the Company's onshore drilling
program during 1997 was approximately $51.2 million, including $39.4 million for
development, $1.9 million for exploration and $9.9 million for leasehold and
lease acquisitions. During 1997 the Company did not make any acquisitions of
onshore producing properties.
 
     For 1998 the Company has budgeted funds to drill approximately 15 wells in
the Charco Area of South Texas, five wells in the Arkoma Basin, two wells in
East Texas and two wells in West Virginia. The Company has identified enough
additional development and exploratory projects on its existing acreage to
maintain an active drilling program for the next four to six years.
 
     The following is a description of several of the Company's most significant
onshore properties:
 
     Charco Field. The Charco Field is located in Zapata County, Texas. The
Company acquired its properties in the Charco Field in July 1996 in the
TransTexas Acquisition. The Company owns a 95% working interest in the
approximately 165 active wells on such properties, all of which are operated by
the Company. During December 1997, the Company's Charco Field properties had
average production of 92,000 Mcfe/d, net to the Company. The Company has
purchased and commenced interpretation of 3-D seismic data covering 148 square
miles of its Charco Field properties. The Company commenced an active drilling
and workover program beginning in the fourth quarter of 1996 to fully exploit
this property and currently has two drilling rigs under long-term contract.
During 1997, the Company successfully drilled and completed 22 development wells
and drilled five unsuccessful development wells. Subsequent to year end, the
Company has drilled five successful and one unsuccessful development well and is
currently drilling two new development wells.
 
     Chismville/Massard Field. The Chismville/Massard Field is located in Logan
and Sebastian Counties, Arkansas. The Company owns working interests in
approximately 149 active wells, of which it operates 80 wells. Working interests
range from 11% to 100% and average approximately 73%. During 1997, the Company
successfully completed eight gross (5.8 net) development wells and three gross
(2.9 net) unsuccessful development wells. During December 1997, production
averaged 11,700 Mcfe/d, net to the Company.
 
     Willow Springs and Surrounding Fields. The Willow Springs Field is located
in Gregg County, Texas, with surrounding fields located in Panola and Harrison
Counties, Texas. The Company owns working interests in 63 active wells, of which
it operates 20 wells. Working interests range from 3% to 100% and average
approximately 53%. During 1997, the Company participated in the drilling of one
gross (0.4 net) successful development well in this area. During December 1997,
production averaged 3,100 Mcfe/d, net to the Company.
 
     Wilburton, Panola and Surrounding Fields. The Wilburton and Panola Fields
are located in Latimer County, Oklahoma. The Company owns working interest in 51
active wells, of which it operates 18 wells. Working interests range from 1% to
63% and average approximately 23%. During 1997, the Company participated in the
successful drilling of two exploratory wells in which it had a small combined
working interest of 8%. In 1998, the Company participated in one successful
development well, currently being completed, in which it has a working interest
of 11%. During December 1997, production averaged 5,000 Mcfe/d, net to the
Company.
 
     Appalachian Area. The Belington, Clarksburg and Seneca Upshur Fields are
located in Barbour, Randolph, Upshur and Mingo Counties, West Virginia. The
Company owns working interests in 670 wells, substantially all of which are
operated by the Company. Working interests range from 6% to 100% and average
approximately 60%. During 1997, the Company drilled and successfully completed
two development wells in this area. During December 1997, production averaged
5,200 Mcfe/d, net to the Company.
 
ADDITIONAL FUTURE PROJECTS
 
     In addition to the properties described above, the Company has accumulated
a large inventory of offshore leases comprised of 251,307 undeveloped gross
(215,514 net) acres. These leases are under review by the Company's geologists
and geophysicists based upon 3-D seismic data acquired in recent years. The
Company
                                       47
<PAGE>   49
 
has established a team of geologists and geophysicists to continually evaluate
unleased acreage offshore which will be available at upcoming lease sales. The
Company is also actively pursuing farm-ins from other companies, interests in
other companies' joint ventures and potential acquisitions. Finally, the Company
is also evaluating its producing properties for workovers and recompletions
which it will undertake in the next several years.
 
NATURAL GAS AND OIL RESERVES
 
     The following table summarizes the estimates of the Company's historical
net proved reserves as of December 31, 1995, 1996 and 1997, and the present
values attributable to these reserves at such dates. The reserve data and
present values as of December 31, 1997 were prepared by Netherland, Sewell &
Associates, Inc. ("NSA") and Miller and Lents, Ltd. ("Miller and Lents"),
independent petroleum engineering consultants. The reserve data and present
values as of December 31, 1996 and 1995 were prepared by NSA, Miller and Lents,
Ryder Scott Company ("Ryder Scott") and Huddleston & Co., Inc. ("Huddleston").
 
<TABLE>
<CAPTION>
                                                                AS OF DECEMBER 31,
                                                          ------------------------------
                                                            1995       1996       1997
                                                          --------   --------   --------
                                                                  (IN THOUSANDS)
<S>                                                       <C>        <C>        <C>
Net Proved Reserves(1):
  Natural gas (MMcf)....................................   195,946    320,474    330,601
  Oil (MBbls)...........................................       889      1,131      1,077
  Total (MMcfe).........................................   201,280    327,260    337,063
Present value of future net revenues before income
  taxes(2)..............................................  $206,574   $577,000   $377,065
Standardized measure of discounted future net cash
  flows(3)..............................................  $171,459   $452,582   $315,380
</TABLE>
 
- ---------------
 
(1) NSA and Miller and Lents prepared reserve data and present values with
    respect to properties comprising approximately 73% and 27%, respectively, of
    the present values attributable to the Company's proved reserves as of
    December 31, 1997. NSA, Miller and Lents, Ryder Scott and Huddleston
    prepared reserve data and present values with respect to properties
    comprising approximately 47%, 30%, 23%, and 0%, respectively, of the present
    values attributable to the Company's proved reserves as of December 31,
    1996, and 14%, 52%, 32%, and 2%, respectively, of the present values
    attributable to the Company's proved reserves as of December 31, 1995.
 
(2) The present value of future net revenues attributable to the Company's
    reserves was prepared using prices in effect at the end of the respective
    periods presented, discounted at 10% per annum on a pretax basis. Average
    prices per Mcf of natural gas, used in making such present value
    determinations as of December 31, 1995, 1996 and 1997 were $2.06, $3.41 and
    $2.31, respectively. Average prices per Bbl of oil used in making such
    present value determinations as of December 31, 1995, 1996 and 1997 were
    $17.29, $22.94 and $17.23, respectively. Such amounts reflect the effects of
    the Company's hedging contracts.
 
(3) The standardized measure of discounted future net cash flows represents the
    present value of future net revenues after income tax discounted at 10% per
    annum. Such amounts reflect the effects of the Company's hedging contracts.
 
     In accordance with applicable requirements of the Commission, estimates of
the Company's proved reserves and future net revenues are made using sales
prices estimated to be in effect as of the date of such reserve estimates and
are held constant throughout the life of the properties (except to the extent a
contract specifically provides for escalation). Estimated quantities of proved
reserves and future net revenues therefrom are affected by gas prices, which
have fluctuated widely in recent years. There are numerous uncertainties
inherent in estimating natural gas and oil reserves and their estimated values,
including many factors beyond the control of the producer. The reserve data set
forth in this Prospectus represent only estimates. Reservoir engineering is a
subjective process of estimating underground accumulations of natural gas and
oil that cannot be measured in an exact manner. The accuracy of any reserve
estimate is a function of the quality of available data and of engineering and
geological interpretation and judgment. As a result, estimates of different
 
                                       48
<PAGE>   50
 
engineers, including those used by the Company, may vary. In addition, estimates
of reserves are subject to revision based upon actual production, results of
future development and exploration activities, prevailing natural gas and oil
prices, operating costs and other factors, which revision may be material.
Accordingly, reserve estimates are often different from the quantities of
natural gas and oil that are ultimately recovered and are highly dependent upon
the accuracy of the assumptions upon which they are based. The Company's
estimated proved reserves have not been filed with or included in reports to any
federal agency.
 
     The present value of future net revenues before income taxes and the
standardized measure of discounted future net cash flows set forth in this
Prospectus do not reflect any adjustment for after program-payout working
interests held by the Company's President and Chief Executive Officer in certain
properties of the Company. The amounts expected to be payable in respect of such
after program-payout working interests would not have a material effect on the
information presented. See "Certain Transactions."
 
DRILLING ACTIVITY
 
     The following table sets forth the drilling activity of the Company on its
properties for the years ended December 31, 1995, 1996 and 1997.
 
<TABLE>
<CAPTION>
                                                       YEAR ENDED DECEMBER 31,
                                            ---------------------------------------------
                                                1995            1996            1997
                                            ------------    ------------    -------------
                                            GROSS    NET    GROSS    NET    GROSS    NET
                                            -----    ---    -----    ---    -----    ----
<S>                                         <C>      <C>    <C>      <C>    <C>      <C>
OFFSHORE DRILLING ACTIVITY:
Exploratory:
  Productive..............................    1      1.0      6      4.2      6       3.7
  Non-Productive..........................   --      --       4      2.2      3       2.3
                                             --      ---     --      ---     --      ----
          Total...........................    1      1.0     10      6.4      9       6.0
Development:
  Productive..............................    7      2.8      1      0.5      1       0.2
  Non-Productive..........................   --      --      --      --       1       0.8
                                             --      ---     --      ---     --      ----
          Total...........................    7      2.8      1      0.5      2       1.0
ONSHORE DRILLING ACTIVITY:
Exploratory:
  Productive..............................    3      0.5      1      0.1      2       0.1
  Non-Productive..........................   --      --       3      2.2      2       0.6
                                             --      ---     --      ---     --      ----
          Total...........................    3      0.5      4      2.3      4       0.7
Development:
  Productive..............................   12      7.4      9      6.5     33      29.1
  Non-Productive..........................    5      2.5      1      1.0      8       7.7
                                             --      ---     --      ---     --      ----
          Total...........................   17      9.9     10      7.5     41      36.8
</TABLE>
 
                                       49
<PAGE>   51
 
PRODUCTIVE WELLS
 
     The following table sets forth the number of productive wells in which the
Company owned an interest as of December 31, 1997.
 
<TABLE>
<CAPTION>
                                            COMPANY                             TOTAL
                                            OPERATED       NON-OPERATED       PRODUCTIVE
                             COMPANY         WELLS             WELLS            WELLS
                            OPERATED     --------------    -------------    --------------
                            PLATFORMS    GROSS     NET     GROSS    NET     GROSS     NET
                            ---------    -----    -----    -----    ----    -----    -----
<S>                         <C>          <C>      <C>      <C>      <C>     <C>      <C>
OFFSHORE
Gas.......................     18          56      35.8      12      2.6       68     38.4
Oil.......................     --          --        --       4      0.5        4      0.5
                               --         ---     -----     ---     ----    -----    -----
          Total...........     18          56      35.8      16      3.1       72     38.9
                               --         ---     -----     ---     ----    -----    -----
ONSHORE
Gas.......................                949     695.6     151     33.6    1,100    729.2
Oil.......................                  2       1.9       2      0.5        4      2.4
                                          ---     -----     ---     ----    -----    -----
          Total...........                951     697.5     153     34.1    1,104    731.6
                                          ---     -----     ---     ----    -----    -----
</TABLE>
 
     Productive wells consist of producing wells capable of production,
including gas wells awaiting connections. Wells that are completed in more than
one producing horizon are counted as one well.
 
ACREAGE DATA
 
     The following table sets forth the approximate developed and undeveloped
acreage in which the Company held a leasehold mineral or other interest as of
December 31, 1997. Undeveloped acreage includes leased acres on which wells have
not been drilled or completed to a point that would permit the production of
commercial quantities of natural gas and oil, regardless of whether or not such
acreage contains proved reserves:
 
<TABLE>
<CAPTION>
                                               DEVELOPED ACRES      UNDEVELOPED ACRES
                                              ------------------    ------------------
                                               GROSS       NET       GROSS       NET
                                              -------    -------    -------    -------
<S>                                           <C>        <C>        <C>        <C>
Offshore(1).................................  142,786     77,323    251,307    215,514
Onshore.....................................  157,132    120,914      9,331      5,697
                                              -------    -------    -------    -------
          Total.............................  299,918    198,237    260,638    221,211
                                              =======    =======    =======    =======
</TABLE>
 
- ---------------
 
(1) Offshore includes acreage in federal and state waters.
 
MARKETING AND CUSTOMERS
 
     Substantially all of the Company's production is sold at market prices. The
Company sold 38% and 27% of its natural gas production in 1997 and 1996,
respectively, to H&N Gas Ltd., an unaffiliated third party. Prior to October
1996, the Company agreed, subject to certain conditions, to sell substantially
all of its subsequently developed or acquired gas production, to an affiliate of
Brooklyn Union, PennUnion Energy Services, L.L.C. ("PennUnion"). The gas sales
agreement with PennUnion was terminated in September 1996 when Brooklyn Union
sold its interest in PennUnion; however, PennUnion still remains a purchaser of
the Company's natural gas production. The gas production sold to PennUnion is
sold at market prices, based upon an index price adjusted to reflect the point
of delivery of such production. During 1996 and 1995 sales to PennUnion and
BRING Gas Services Corp. ("BRING"), predecessor to PennUnion and then an
affiliate of Brooklyn Union, accounted for 40% and 46% of total revenues,
respectively. In 1997, sales to PennUnion accounted for less than 10% of total
revenues. The Company believes that the prices at which it sold gas to PennUnion
and BRING were similar to those it would be able to obtain in the open market.
No customer other than H&N Gas Ltd., PennUnion and BRING purchased more than 10%
of the Company's natural gas production during the past three years. The Company
believes that the loss of any such customer
 
                                       50
<PAGE>   52
 
would not have a material adverse effect on the Company's operations. See Note 9
to the Company's Combined Financial Statements.
 
     The Company enters into commodity swaps with unaffiliated third parties for
portions of its natural gas production to achieve more predictable cash flows
and to reduce its exposure to short-term fluctuations in gas prices. See
"Management's Discussion and Analysis of Financial Condition and Results of
Operations -- General."
 
     Most of the Company's natural gas is transported through gas gathering
systems and gas pipelines which are not owned by the Company. Transportation
space on such gathering systems and pipelines is occasionally limited and at
times unavailable due to repairs or improvements being made to such facilities
or due to such space being utilized by other gas shippers with priority
transportation agreements. While the Company's inability to market its natural
gas has been subject to limitations or delays only on an infrequent basis, if
transportation space is restricted or is unavailable, the Company's cash flow
from the affected properties could be adversely affected. See "-- Regulation"
and "Risk Factors -- Operating Risks of Natural Gas and Oil Operations."
 
ABANDONMENT COSTS
 
     The Company is responsible for the payment of abandonment costs on the
natural gas and oil properties pro rata to its working interest. The Company
provides for its expected future abandonment liabilities by accruing for such
costs as a component of depletion, depreciation and amortization as the
properties are produced. As of December 31, 1997, total undiscounted abandonment
costs estimated to be incurred through the year 2008 were approximately $7.0
million for properties in the federal and state waters and are not considered
significant for onshore properties. Estimates of abandonment costs and their
timing may change due to many factors including actual drilling and production
results, inflation rates, and changes in environmental laws and regulations.
 
     The Minerals Management Service ("MMS") requires lessees of Outer
Continental Shelf properties to post bonds in connection with the plugging and
abandonment of wells located offshore and the removal of all production
facilities. Operators in the Outer Continental Shelf waters of the Gulf of
Mexico are currently required to post an area wide bond of $3 million or
$500,000 per producing lease. The Company is presently exempt from any
requirement by MMS to provide supplemental bonding on its offshore leases,
although no assurance can be made that it will continue to satisfy the
requirements for such exemption in the future. Whether or not the Company
qualifies for such exemption, the Company does not believe that the cost of any
such bonding requirements will materially affect the Company's financial
condition or results of operations. Under certain circumstances, the MMS has the
authority to suspend or terminate operations on federal leases for failure to
comply with applicable bonding requirements or other regulations applicable to
plugging and abandonment. Any such suspensions or terminations of the Company's
operations could have a material adverse effect on the Company's financial
condition and results of operations.
 
TITLE TO PROPERTIES
 
     As is customary in the oil and gas industry, the Company makes only a
cursory review of title to farmout acreage and to undeveloped natural gas and
oil leases upon execution of the contracts. Prior to the commencement of
drilling operations, a thorough title examination is conducted and curative work
is performed with respect to significant defects. To the extent title opinions
or other investigations reflect title defects, the Company, rather than the
seller of the undeveloped property, is typically responsible for curing any such
title defects at its expense. If the Company were unable to remedy or cure any
title defect of a nature such that it would not be prudent to commence drilling
operations on the property, the Company could suffer a loss of its entire
investment in the property. The Company has obtained title opinions on
substantially all of its producing properties and believes that it has
satisfactory title to such properties in accordance with standards generally
accepted in the oil and gas industry. Prior to completing an acquisition of
producing natural gas and oil leases, the Company obtains title opinions on the
most significant leases. The Company's natural gas and oil properties are
subject to customary royalty interests, liens for current taxes and other
 
                                       51
<PAGE>   53
 
burdens which the Company believes do not materially interfere with the use of
or affect the value of such properties.
 
THIRD PARTY CONTRACTORS
 
     In an effort to control costs, the Company entered into a contract with
Operators & Consulting Services, Inc. ("OCS") pursuant to which OCS provides
professional services to the Company in the areas of drilling, production and
construction for offshore properties. OCS provides (i) engineering and field
supervision for well design, drilling, completion and workover operations; (ii)
supervision of the daily production operations and field personnel to operate
and maintain production facilities; and (iii) coordination and review of third
party engineering and fabrication work, and installation supervision of
platforms, production facilities and pipelines. The Company has maintained this
contractual relationship with OCS since 1989.
 
COMPETITION
 
     The Company encounters competition from other oil and gas companies in all
areas of its operations, including the acquisition of producing properties. The
Company's competitors include major integrated oil and gas companies and
numerous independent oil and gas companies, individuals and drilling and income
programs. Many of its competitors are large, well-established companies with
substantially larger operating staffs and greater capital resources than the
Company's and which, in many instances, have been engaged in the oil and gas
business for a much longer time than the Company. Such companies may be able to
pay more for productive natural gas and oil properties and exploratory prospects
and to define, evaluate, bid for and purchase a greater number of properties and
prospects than the Company's financial or human resources permit. The Company's
ability to acquire additional properties and to discover reserves in the future
will be dependent upon its ability to evaluate and select suitable properties
and to consummate transactions in this highly competitive environment.
 
OPERATING HAZARDS AND UNINSURED RISKS
 
     The Company's operations are subject to hazards and risks inherent in
drilling for and production and transportation of natural gas and oil, such as
fires, natural disasters, explosions, encountering formations with abnormal
pressures, blowouts, cratering, pipeline ruptures, and spills, any of which can
result in loss of hydrocarbons, environmental pollution, personal injury claims,
and other damage to properties of the Company and others. Additionally, certain
of the Company's natural gas and oil operations are located in an area that is
subject to tropical weather disturbances, some of which can be severe enough to
cause substantial damage to facilities and possibly interrupt production. As
protection against operating hazards, the Company maintains insurance coverage
against some, but not all, potential losses. The Company's coverages include,
but are not limited to, operator's extra expense, to include loss of well,
blowouts and certain costs of pollution control, physical damage on certain
assets, employer's liability, comprehensive general liability, automobile and
worker's compensation. The Company believes that its insurance is adequate and
customary for companies of a similar size engaged in operations similar to those
of the Company, but losses could occur for uninsurable or uninsured risks or in
amounts in excess of existing insurance coverage. The occurrence of an event
that is not fully covered by insurance could have an adverse impact on the
Company's financial condition and results of operations.
 
REGULATION
 
     The availability of a ready market for natural gas and oil production
depends upon numerous factors beyond the Company's control. These factors
include regulation of natural gas and oil production, federal and state
regulations governing environmental quality and pollution control, state limits
on allowable rates of production by a well or proration unit, the supply of
natural gas and oil available for sale, the availability of adequate pipeline
and other transportation and processing facilities and the marketing of
competitive fuels. For example, a productive natural gas well may be "shut-in"
because of an oversupply of natural gas or the lack of an available natural gas
pipeline in the areas in which the Company may conduct operations.
 
                                       52
<PAGE>   54
 
     Regulation of Oil and Gas Exploration and Production. Exploration and
production operations of the Company are subject to various types of regulation
at the federal, state and local levels. Such regulation includes requiring
permits for the drilling of wells, maintaining bonding requirements in order to
drill or operate wells, and regulating the location of wells, the method of
drilling and casing wells, the surface use and restoration of properties upon
which wells are drilling and the plugging and abandonment of wells. The
Company's operations are also subject to various conservation laws and
regulations. These include the regulation of the size of drilling and spacing
units or proration units and the density of wells which may be drilled and
unitization or pooling of oil and gas properties. In this regard, some states
allow the forced pooling or integration of tracts to facilitate exploration
while other states rely on voluntary pooling of lands and leases. In addition,
state conservation laws establish maximum rates of production from natural gas
and oil wells, generally prohibit the venting or flaring of natural gas and
impose certain requirements regarding the ratability of production. The effect
of these regulations is to limit the amounts of natural gas and oil the
Company's operator or the Company can produce from its wells, and to limit the
number of wells or the locations of which the Company can drill. Legislation
affecting the oil and gas industry also is under constant review for amendment
or expansion. Generally, state-established allowables have been influenced by
overall natural gas market supply and demand in the United States, as well as
the specific "nominations" for natural gas from the parties who produce or
purchase gas from the field and other factors deemed relevant by the agency. The
Company cannot predict whether further changes will be made in how these states
set allowables or what impact, if any, such further changes might have. In
addition, numerous departments and agencies, both federal and state, are
authorized by statute to issue rules and regulations binding on the oil and gas
industry and its individual members, some of which carry substantial penalties
for failure to comply. The regulatory burden on the oil and gas industry
increases the Company's cost of doing business and, consequently, affects its
profitability. Inasmuch as such laws and regulations are frequently expanded,
amended or reinterpreted, the Company is unable to predict the future cost or
impact of complying with such regulations.
 
     Natural Gas Marketing and Transportation. Federal legislation and
regulatory controls in the United States have historically affected the price of
the natural gas produced by the Company and the manner in which such production
is marketed. The Federal Energy Regulatory Commission (the "FERC") has
jurisdiction over the transportation and sale for resale of natural gas in
interstate commerce by natural gas companies under the Natural Gas Act of 1938
(the "NGA"). Although maximum selling prices of natural gas were formerly
regulated under the NGA and the Natural Gas Policy Act of 1978 (the "NGPA"), on
July 26, 1989, the Natural Gas Wellhead Decontrol Act of 1989 (the "Decontrol
Act") amended the NGPA to remove completely by January 1, 1993 price and
non-price controls for all "first sales" of domestic natural gas, which include
all sales by the Company of its own production. Consequently, sales of the
Company's natural gas production currently may be made at market prices, subject
to applicable contract provisions. The FERC's jurisdiction over natural gas
transportation was unaffected by the Decontrol Act.
 
     In July 1994, the FERC eliminated a regulation that had rendered virtually
all sales of natural gas by pipeline and distribution company affiliates, such
as the Company, to be deregulated first sales. Although several parties
challenged the FERC's action, in 1996 the United States Court of Appeals for the
District of Columbia Circuit (the "D.C. Circuit Court") upheld the FERC's
elimination of the regulation. As a result, all sales by the Company of gas for
resale in interstate commerce, other than sales by the Company of its own
production, are now subject to NGA jurisdiction. This includes, for example,
sales for resale of gas purchased from third parties. The Company does not
anticipate this change will have any significant current adverse effects in
light of the market based sales authority under existing blanket certificates.
Such sales are subject to the future possibility of greater federal oversight,
however, including the possibility the FERC might prospectively impose more
restrictive conditions on such sales.
 
     The FERC also regulates interstate natural gas transportation rates and
service conditions, which affect the marketing of natural gas produced by the
Company, as well as the revenues received by the Company for sales of such
natural gas. Since the latter part of 1985, the FERC has endeavored to make
interstate natural gas transportation more accessible to natural gas buyers and
sellers on an open and nondiscriminatory basis. The FERC's efforts have
indirectly but significantly altered the marketing and pricing of natural gas.
Commencing in April 1992, the FERC issued Order Nos. 636, 636-A and 636-B
(collectively, "Order
 
                                       53
<PAGE>   55
 
No. 636"), which, among other things, required interstate pipelines to
"restructure" to provide transportation separate or "unbundled" from the
pipelines' sales of natural gas. Also, Order No. 636 required pipelines to
provide open-access transportation on a basis that is equal for all natural gas
supplies. In most instances, the result of the Order No. 636 and related
initiatives has been to substantially reduce or bring to an end the interstate
pipelines' traditional role as wholesalers of natural gas in favor of providing
only storage and transportation services. The FERC has issued final orders in
the individual pipeline restructuring proceedings relating to the implementation
of Order No. 636, and has performed a series of one year reviews to determine
whether refinements are required regarding individual pipeline implementations
of Order No. 636. While a number of the individual pipeline restructuring
proceedings were appealed to the federal courts of appeal, only a few are
currently pending on appeal and those cases generally deal with limited
pipeline-specific issues.
 
     Several parties appealed various parts of Order No. 636, and in July 1996
the D.C. Circuit Court issued its decision in those appeals. The D.C. Circuit
Court largely upheld the basic tenets of Order No. 636, including the
requirements that interstate pipelines "unbundle" their sales of gas from
transportation and provide open-access transportation on a basis that is equal
for all gas suppliers. The D.C. Circuit Court remanded several relatively narrow
issues for further explanation by the FERC. On remand, in Order No. 636-C, the
FERC reaffirmed the holding of Order No. 636 that pipelines should be entitled
to recover 100 percent of their prudently incurred GSR costs. In addition, the
FERC reduced the contract matching cap for the right-of-first-refusal mechanism
to five years. The FERC also decided not to limit a pipeline's no-notice service
to its bundled sales customers at the time of restructuring, and reaffirmed that
pipelines should focus on individual customers, rather than customer classes, in
mitigating the effects of SFV rate design. Order No. 636-C is currently pending
on rehearing the FERC.
 
     Although Order No. 636 does not regulate natural gas producers such as the
Company, the FERC has stated that Order No. 636 is intended to foster increased
competition within all phases of the natural gas industry. It is unclear what
impact, if any, increased competition within the natural gas industry under
Order No. 636 will have on the Company and its natural gas marketing efforts.
While Order No. 636 could provide the Company with additional market access and
more fairly applied transportation service rates, terms and conditions, it could
also subject the Company to more restrictive pipeline imbalance tolerances and
greater penalties for violation of those tolerances. The Company does not
believe, however, that it will be affected by Order No. 636, or by any action
taken by the FERC on rehearing of Order No. 636-C, materially differently than
other natural gas producers and marketers with which it competes.
 
     The FERC issued a statement of policy in January 1996 concerning
alternatives to its traditional cost-of-service ratemaking methodology. This
policy statement articulates the criteria that the FERC will use to evaluate
proposals to charge market-based rates for the transportation of natural gas,
and also provides that the FERC will consider proposals for negotiated rates for
individual shippers of natural gas so long as a cost-of-service-based rate also
is available. In a related policy statement, the FERC also requested comments on
whether it should allow gas pipelines the flexibility to negotiate the terms and
conditions of transportation service with prospective shippers. The Company
cannot predict what further action the FERC will take on these matters; however,
the Company does not believe that it will be affected by any action taken
materially differently than other natural gas producers and marketers with which
it competes.
 
     The FERC has recently commenced a reexamination of certain of its
transportation-related policies, including the manner in which interstate
pipeline shippers may release interstate pipeline capacity under Order No. 636
for resale in the secondary markets. The Company cannot predict what action the
FERC will take on these matters, nor can it accurately predict whether the
FERC's actions will achieve the goal of increasing competition in markets in
which the Company's natural gas is sold. However, the Company does not believe
that it will be affected by any action taken materially differently than other
natural gas producers and marketers with which it competes.
 
     The FERC has also issued a policy statement on how interstate natural gas
pipelines can recover the costs of new pipeline facilities. While the FERC's
policy statement on new construction cost recovery affects the Company only
indirectly, in its present form, the new policy should enhance competition in
natural gas markets and facilitate construction of gas supply laterals. The FERC
has also issued numerous decisions that
 
                                       54
<PAGE>   56
 
address how it intends to regulate natural gas gathering facilities owned (or
previously owned but either "spun down" to an affiliate or "spun off" to a
non-affiliate) by interstate pipeline companies after Order No. 636.
Specifically, the FERC has approved the spin down or spin off by numerous
interstate pipelines of their gathering facilities. These approvals were given
despite the strong protests of a number of producers concerned that any
diminution in FERC's oversight of interstate pipeline-related gathering services
might result in a denial of open access or otherwise subject producers to a
pipeline's monopoly power. The FERC has stated that in the future it may
regulate gathering activities if a gatherer acts in concert with its pipeline
affiliate in a manner that frustrates the FERC's effective regulation of a
pipeline. It is unclear what effect the FERC's new gathering policy will have on
producers such as the Company and the Company cannot predict what further action
the FERC will take in this regard.
 
     On February 28, 1996, the FERC issued a Statement of Policy regarding the
application of its jurisdiction under the NGA and OCSLA over new natural gas
facilities and services on the Outer Continental Shelf. In its Policy Statement,
the FERC concluded that it will retain its existing primary function test to
determine whether particular facilities on the Outer Continental Shelf
constitute gathering facilities exempt from the FERC's NGA jurisdiction.
However, the FERC added a new factor to its primary function test for facilities
that are designed to collect gas produced in water depths of 200 meters or more.
Such facilities now will be presumed to qualify as gathering facilities up to
the point or points of potential connection with the interstate pipeline grid.
Downstream of that point, the facilities will be evaluated under the existing
primary function test. Existing interstate pipelines and gathering facilities
would retain their present status barring some change in circumstances. On June
14, 1996, the Commission dismissed all requests for rehearing of its February
28, 1996 order. With respect to this policy statement, the Company does not
believe that it will be affected by any action taken materially differently than
other natural gas producers and marketers with which it competes.
 
     The Fifth Circuit Court of Appeals recently remanded a FERC decision which
declared certain offshore facilities to be subject to its jurisdiction. The
Fifth Circuit decision required the FERC to revisit its methodology for
determining whether it has jurisdiction over offshore natural gas pipeline
facilities. It is not clear whether a revised FERC policy regarding its
jurisdiction over offshore natural gas pipeline facilities will have a material
effect on producers such as the Company and the Company cannot predict what this
new policy would entail.
 
     On July 17, 1996, the FERC issued Order No. 587 which revised the FERC's
regulations to require interstate natural gas pipelines to follow standardized
procedures issued by the Gas Industry Standards Board ("GISB") for certain
business practices, i.e., nominations, allocations, balancing, measurement,
invoicing, capacity release and electronic communication between the pipelines
and those with whom they do business. On January 30, 1997, in Order No. 587-B,
the FERC incorporated into its regulations a second set of GISB standards that
would, inter alia, require interstate pipelines to conduct business transactions
and provide other information according to Internet protocols and to abide by
certain business practice standards dealing with nomination, flowing gas and
capacity release. On March 4, 1997, the FERC issued Order No. 587-C which
amended the FERC's regulations to adopt standards requiring interstate pipelines
to publish certain information on Internet web pages and to implement new
business practice standards covering nominations and flowing gas. The intent of
these standards adopted pursuant to Order Nos. 587, et seq., is to establish a
more efficient and integrated pipeline grid which will reduce the variations in
pipeline business practices and allow buyers to obtain and transport gas from
all potential sources of supply more easily and efficiently. The FERC has denied
requests for rehearing of Order Nos. 587, et seq. An appeal of Order No. 587 is
pending before the D.C. Circuit Court. With respect to GISB issues, the Company
does not believe that it will be affected by any action taken materially
differently than other natural gas producers and marketers with which it
competes.
 
     Additional proposals and proceedings that might affect the natural gas
industry are considered from time to time by Congress, the FERC, state
regulatory bodies and the courts. The Company cannot predict when or if any such
proposals might become effective, or their effect, if any, on the Company's
operations. The natural gas industry historically has been very heavily
regulated; therefore, there is no assurance that the generally less stringent
regulatory approach recently pursued by the FERC and Congress will continue
indefinitely into the future.
                                       55
<PAGE>   57
 
     Offshore Leasing. Certain operations the Company conducts are on federal
oil and gas leases, which the MMS administers. The MMS issues such leases
through competitive bidding. These leases contain relatively standardized terms
and require compliance with detailed MMS regulations and orders pursuant to the
Outer Continental Shelf Lands Act ("OCSLA") (which are subject to change by the
MMS). For offshore operations, lessees must obtain MMS approval for exploration
plans and development and production plans prior to the commencement of such
operations. In addition to permits required from other agencies (such as the
Coast Guard, the Army Corps of Engineers and the Environmental Protection
Agency), lessees must obtain a permit from the MMS prior to the commencement of
drilling. The MMS has promulgated regulations requiring offshore production
facilities located on the Outer Continental Shelf to meet stringent engineering
and construction specifications, and has recently proposed additional
safety-related regulations concerning the design and operating procedures for
Outer Continental Shelf production platforms and pipelines. The MMS also has
issued regulations restricting the flaring or venting of natural gas, and has
recently proposed to amend such regulations to prohibit the flaring of liquid
hydrocarbons and oil without prior authorization. Similarly, the MMS has
promulgated other regulations governing the plugging and abandonment of wells
located offshore and the removal of all production facilities. To cover the
various obligations of lessees on the Outer Continental Shelf, the MMS generally
requires that lessees post substantial bonds or other acceptable assurances that
such obligations will be met. The cost of such bonds or other surety can be
substantial and there is no assurance that the Company can obtain bonds or other
surety in all cases. See "-- Environmental Matters."
 
     In addition, the MMS is conducting an inquiry into certain contract
settlement agreements from which producers on MMS leases have received
settlement proceeds that are royalty bearing and the extent to which producers
have paid the appropriate royalties on those proceeds. The MMS has recently
issued a final rule governing valuation for royalty purposes of gas produced
from federal and Indian leases to primarily address allowances for
transportation of gas. The amendments clarify the methods by which gas royalties
and deductions for gas transportation are calculated. The Company does not
believe that these amended regulations will affect the Company materially
differently than other natural gas producers and marketers with which it
competes.
 
     The MMS has recently issued a notice of proposed rulemaking in which it
proposes to amend its regulations governing the calculation of royalties and the
valuation of natural gas produced from federal leases. The principal feature in
the amendments, as proposed, would establish an alternative market-index based
method to calculate royalties on certain natural gas production sold to
affiliates or pursuant to non-arm's-length contracts. The MMS has proposed this
rulemaking to facilitate royalty valuation in light of changes in the natural
gas marketing environment. The Company cannot predict what action the MMS will
take on these matters, nor can it predict at this state of the rulemaking
proceeding how the Company might be affected by amendments to the regulations.
 
     The OCSLA requires that all pipelines operating on or across the Outer
Continental Shelf provide open-access, non-discriminatory service. Although the
FERC has opted not to impose the regulations of Order No. 509, which implements
these requirements to the OCSLA, on gatherers and other nonjurisdictional
entities, the FERC has retained the authority to exercise jurisdiction over
those entities if necessary to permit non-discriminatory access to services on
the Outer Continental Shelf. If the FERC were to apply Order No. 509 to
gatherers in the Outer Continental Shelf, eliminate the exemption of gathering
lines, and redefine its jurisdiction over gathering lines, then these acts could
result in a reduction in available pipeline space for existing shippers, such as
the Company, in the Gulf of Mexico and elsewhere.
 
     Oil Sales and Transportation Rates. Sales of crude oil, condensate and gas
liquids by the Company are not regulated and are made at market prices. The
price the Company receives from the sale of these products is affected by the
cost of transporting the products to market. Effective as of January 1, 1995,
the FERC implemented regulations establishing an indexing system for
transportation rates for oil pipelines, which would generally index such rates
to inflation, subject to certain conditions and limitations. These regulations
were affirmed by the D.C. Circuit Court on May 10, 1996. Because of the
uncertainty surrounding the indexing methodology, as well as the possibility of
the use of cost-of-service ratemaking and market-based rates, the
 
                                       56
<PAGE>   58
 
Company is not able at this time to predict the effects of these regulations, if
any, on the Company's oil producing operations.
 
     Safety Regulation. The Company's gathering operations are subject to safety
and operational regulations relating to the design, installation, testing,
construction, operation, replacement, and management of facilities. Pipeline
safety issues have recently been the subject of increasing focus in various
political and administrative arenas at both the state and federal levels. In
addition, the major federal pipeline safety law is subject to change this year
as it is considered for reauthorization by Congress. For example, federal
legislation addressing pipeline safety issues has been introduced, which, if
enacted, would establish a federal "one call" notification system. Additional
pending legislation would, among other things, increase the frequency with which
certain pipelines must be inspected, as well as increase potential civil and
criminal penalties for violations of pipeline safety requirements. The Company
believes its operations, to the extent they may be subject to current natural
gas pipeline safety requirements, comply in all material respects with such
requirements. The Company cannot predict what effect, if any, the adoption of
this or other additional pipeline safety legislation might have on its
operations, but the industry could be required to incur additional capital
expenditures and increased costs depending upon future legislative and
regulatory changes.
 
ENVIRONMENTAL MATTERS
 
     The Company's operations are subject to federal, state and local laws and
regulations governing the discharge of materials into the environment or
otherwise relating to environmental protection. These laws and regulations may
require the acquisition of a permit before drilling commences, restrict the
types, quantities and concentration of various substances that can be released
into the environment in connection with drilling and production activities,
limit or prohibit drilling activities on certain lands lying within wilderness,
wetlands and other protected areas, require remedial measures to prevent
pollution from former operations, such as pit closure and plugging abandoned
wells, and impose substantial liabilities for pollution resulting from the
Company's operations. In addition, these laws, rules and regulations may
restrict the rate of oil and natural gas production below the rate that would
otherwise exist. The regulatory burden on the oil and gas industry increases the
cost of doing business and consequently affects its profitability. Changes in
environmental laws and regulations occur frequently, and any changes that result
in more stringent and costly waste handling, disposal and clean-up requirements
could have a significant impact on the operating costs of the Company, as well
as the oil and gas industry in general. Management believes that the Company is
in substantial compliance with current applicable environmental laws and
regulations and that continued compliance with existing requirements will not
have a material adverse impact on the Company.
 
     The Comprehensive Environmental Response, Compensation and Liability Act
("CERCLA"), also known as the "Superfund" law, imposes liability, without regard
to fault or the original conduct, on certain classes of persons who are
considered to be responsible for the release of a "hazardous substance" into the
environment. These persons include the owner or operator of the disposal site or
sites where the release occurred and companies that disposed or arranged for the
disposal of the hazardous substances. Under CERCLA, such persons may be subject
to joint and several liability for the costs of cleaning up the hazardous
substances that have been released into the environment, for damages to natural
resources and for the costs of certain health studies, and it is not uncommon
for neighboring landowners and other third parties to file claims for personal
injury and property damage allegedly caused by the release of hazardous
substances.
 
     The Oil Pollution Act of 1990 (the "OPA"), as amended by the Coast Guard
Authorization Act of 1996, (collectively, "OPA"), and regulations thereunder
impose a variety of requirements on "responsible parties" related to the
prevention of oil spills and liability for damages resulting from such spills in
"waters of the United States." A "responsible party" includes the owner or
operator of a facility or vessel, or the lessee or permittee of the area in
which an offshore facility is located. The term "waters of the United States"
has been broadly defined to include not only the waters of the Gulf of Mexico
but also inland water bodies, including wetlands, playa lakes and intermittent
streams. The OPA also requires owners and operators of offshore facilities to
establish and maintain evidence of oil spill financial responsibility ("OSFR")
for costs attributable to oil spills. Under the Coast Guard Authorization Act of
1996, the definition of offshore facility includes facilities located in coastal
inland waters, such as bays or estuaries. OPA requires a minimum of $35 million
in
                                       57
<PAGE>   59
 
OSFR for offshore facilities located on the Outer Continental Shelf and a
minimum of $10 million for offshore facilities located landward of the seaward
boundary of a State. This amount is subject to upward regulatory adjustment up
to $150 million. Responsible parties for more than one offshore facility are
required to provide OSFR only for their offshore facility requiring the highest
OSFR. On March 25, 1997, the Minerals Management Service proposed regulations
for establishing the amount of OSFR to be required for particular facilities.
Under the proposed rule, the amount of OSFR will increase as the volume of a
facility's worst-case oil spill increases. Accordingly, for Outer Continental
Shelf facilities with worst-case spills of less than 35,000 barrels, only $35
million in OSFR will be required; for worst-case spills of over 35,000 barrels,
$70 million will be required; for worst-case spills of over 70,000 barrels, $105
million will be required; and for worst-case spills of over 105,000 barrels,
$150 million will be required. In addition, all OSFR below $150 million remains
subject to upward regulatory adjustment if warranted by the particular
operational, environmental, human health or other risks involved with a
facility. Although the current environmental regulation has had no material
adverse effect of the Company, the impact of the recently adopted and proposed
regulatory changes, and of future environmental regulatory developments such as
stricter environmental regulation and enforcement policies, cannot presently be
quantified.
 
     OPA imposes a variety of additional requirements on responsible parties for
vessels or oil and gas facilities related to the prevention of oil spills and
liability for damages resulting from such spills in waters of the United States.
OPA assigns liability to each responsible party for oil spill removal costs and
a variety of public and private damages from oil spills. While liability limits
apply in some circumstances, a party cannot take advantage of liability limits
if the spill is caused by gross negligence or willful misconduct or resulted
from violation of a federal safety, construction or operating regulation. If a
party fails to report a spill or to cooperate fully in the cleanup, liability
limits likewise do not apply. OPA establishes a liability limit for offshore
facilities of all removal costs plus $75 million. Few defenses exist to the
liability for oil spills imposed by OPA. OPA also imposes other requirements on
facility operators, such as the preparation of an oil spill contingency plan.
Failure to comply with ongoing requirements or inadequate cooperation in a spill
event may subject a responsible party to civil or criminal enforcement actions.
As of this date, the Company is not the subject of any civil or criminal
enforcement actions under the OPA.
 
     In addition, the OCSLA authorizes regulations relating to safety and
environmental protection applicable to lessees and permittees operating in the
Outer Continental Shelf. Specific design and operational standards may apply to
Outer Continental Shelf vessels, rigs, platforms, vehicles and structures.
Violations of lease conditions or regulations issued pursuant to OCSLA can
result in substantial civil and criminal penalties, as well as potential court
injunctions curtailing operations and the cancellation of leases. Such
enforcement liabilities can result from either governmental or private
prosecution. As of this date, the Company is not the subject of any civil or
criminal enforcement actions under OCSLA.
 
     The Federal Water Pollution Control Act ("FWPCA") imposes restrictions and
strict controls regarding the discharge of produced waters and other oil and gas
wastes into navigable waters. Permits must be obtained to discharge pollutants
to state and federal waters. The FWPCA provides for civil, criminal and
administrative penalties for any unauthorized discharges of oil and other
hazardous substances in reportable quantities and, along with the OPA, imposes
substantial potential liability for the costs of removal, remediation and
damages. State laws for the control of water pollution also provide varying
civil, criminal and administrative penalties and liabilities in the case of a
discharge of petroleum or its derivatives into state waters. In January 1995,
the U.S. Environmental Protection Agency ("EPA") issued general permits
prohibiting the discharge of produced water and produced sand derived from oil
and gas point source facilities to coastal waters in Louisiana and Texas,
effective February 8, 1995. However, concurrent with this action, EPA Region VI
issued an administrative order effectively delaying the prohibition on
discharges of produced water and produced sands to January 1, 1997, unless an
earlier compliance date is required by the State. Although the costs to comply
with zero discharge mandates under federal or state law may be significant, the
entire industry will experience similar costs and the Company believes that
these costs will not have a material adverse impact on the Company's financial
conditions and operations. Some oil and gas exploration and production
facilities are required to obtain permits for their storm water discharges.
Costs may be associated with treatment of wastewater or developing storm water
pollution prevention plans. Further, the Coastal Zone Management Act
 
                                       58
<PAGE>   60
 
authorizes state implementation and development of programs of management
measures for nonpoint source pollution to restore and protect coastal waters.
 
EMPLOYEES
 
     As of December 31, 1997, the Company had 104 full time employees, 60 of
whom are located at the Company's headquarters in Houston, Texas and the
remainder of whom are located at field offices. None of the Company's employees
are represented by a labor union. The Company contracts with OCS to conduct all
of the day to day operations of the Company's offshore properties. See "-- Third
Party Contractors."
 
OFFICES
 
     The Company currently leases approximately 71,100 square feet of office
space in Houston, Texas, where its principal offices are located. In addition,
the Company maintains field operations offices in the areas where it operates
onshore properties.
 
LEGAL PROCEEDINGS
 
     The properties purchased in the TransTexas Acquisition are subject to a
judgment lien imposed on substantially all of TransTexas' properties in the
aggregate amount of $18 million. TransTexas has agreed to indemnify the Company
with respect to any loss arising from such judgment lien. TransTexas has
appealed the judgment to which such liens relate, and has posted a bond to
ensure payment of such judgment pending the completion of such appeal. The bond,
in the approximate amount of $18 million, is secured by an irrevocable letter of
credit. The $18 million judgment against TransTexas has been reversed, a
decision which, if upheld, will result in the release of the related judgment
lien. As a result of such arrangements, the Company believes that the properties
purchased in the TransTexas Acquisition are not subject to any material risk
that any such judgment against TransTexas will not be paid.
 
     The Company is not a party to any other material pending legal proceedings,
other than ordinary routine litigation incidental to its business that
management believes will not have a material adverse effect on its financial
condition or results of operations.
 
                                       59
<PAGE>   61
 
                                   MANAGEMENT
 
DIRECTORS
 
     The names of the Directors of the Company, and certain additional
information with respect to each of them, are set forth below.
 
<TABLE>
<CAPTION>
                                                                                      YEAR FIRST
                                                                                       BECAME A
                NAME                   AGE          POSITION WITH THE COMPANY          DIRECTOR
                ----                   ---          -------------------------         ----------
<S>                                    <C>    <C>                                     <C>
James G. Floyd.......................  61     President and Chief Executive Officer
                                              and Director                               1986
Robert B. Catell.....................  60     Chairman of the Board of Directors         1986
Gordon F. Ahalt......................  69     Director                                   1996
Russell D. Gordy.....................  46     Director                                   1986
Craig G. Matthews....................  54     Director                                   1993
James Q. Riordan.....................  70     Director                                   1996
Lester H. Smith......................  55     Director                                   1996
Donald C. Vaughn.....................  61     Director                                   1997
</TABLE>
 
     James G. Floyd has been President and Chief Executive Officer and a
Director of the Company since 1986. Mr. Floyd was President of Seagull E&P Inc.
("Seagull") and a Director of Seagull Energy Corporation, Seagull's parent, from
1981 to 1986. Mr. Floyd was general manager of the offshore division of Houston
Oil and Minerals Corporation ("Houston Oil and Minerals") from 1978 to 1981. Mr.
Floyd joined Houston Oil and Minerals in 1972 after five years as an independent
geologist. Mr. Floyd began his career with Amoco Production Company in 1962. Mr.
Floyd holds a B.S. and an M.S. in geology from the University of Florida.
 
     Robert B. Catell has been Chairman of the Board of Directors of the Company
since 1986. Mr. Catell has been Chairman of the Board and Chief Executive
Officer of Brooklyn Union since 1996 and of KeySpan since September 1997 and was
Chief Executive Officer and President of Brooklyn Union from 1991 to 1996. Mr.
Catell has been associated with Brooklyn Union since 1958 and has been an
officer of Brooklyn Union since 1974. He is also the Chairman of the Board of
Taylor Gas Liquids, Ltd., a publicly traded royalty trust based in Canada. Mr.
Catell received both his Bachelor's and Master's Degrees in Mechanical
Engineering from City College of New York. He holds a Professional Engineer's
License in New York State, and attended Columbia University's Executive
Development Program and Harvard Business School's Advanced Management Program.
Mr. Catell is Trustee of Brooklyn Law School, Independence Savings Bank and
Kingsborough Community College Foundation, Inc.; Chairman and Director of
Alberta Northeast Inc. and Boundary Gas, Inc.; Past Chairman of Energy
Association of New York State; Director and Past Chairman, American Gas
Association; Director of The Business Council of New York State, Inc., Gas
Research Institute, New York City Partnership and New York State Energy Research
and Development Authority.
 
     Gordon F. Ahalt has been a Director of the Company since 1996. Mr. Ahalt
has been President of G.F.A. Inc., a petroleum industry financial and management
consulting firm, since 1982. Mr. Ahalt is a consultant to Brooklyn Union and
W.H. Reaves Co., Inc. Mr. Ahalt serves as a Director for the Bancroft and
Ellsworth Convertible Funds, the Harbinger Group and Cal Dive International. Mr.
Ahalt received a B.S. in Petroleum Engineering in 1951 from the University of
Pittsburgh, attended New York University's Business School and is a graduate of
Harvard Business School's Advanced Management Program. He worked for Amoco
Corporation from 1951 to 1955, Chase Manhattan Bank from 1955 to 1972, White
Weld & Co., Inc. from 1972 to 1973, Chase Manhattan Bank from 1974 through 1976,
served as President and Chief Executive Officer of International Energy Bank
London from 1977 to 1979 and as Chief Financial Officer of Ashland Oil Inc. from
1980 to 1981.
 
     Russell D. Gordy has been a Director of the Company since 1986. Mr. Gordy
has been Managing General Partner of S.G. Interests, a private firm specializing
in oil and gas investments, since 1992. Prior to forming S.G. Interests, Mr.
Gordy was Managing Partner of Northwind Exploration, a private oil and gas firm
 
                                       60
<PAGE>   62
 
formed in 1981 to specialize in exploration along the Texas and Louisiana Gulf
Coast. From 1974 to 1981 Mr. Gordy served in various financial capacities for
Houston Oil and Minerals. Mr. Gordy holds a B.B.A. in accounting from Sam
Houston State University and is a C.P.A. Mr. Gordy is a member of the Board of
Directors, or equivalent governing body in the case of partnerships or limited
liability companies, of SG Interests I-IV, Gordy Oil Company, Gordy Gas
Corporation, San Juan Compression, L.L.C., SG Interests, Inc., SG Methane
Company, Inc., Gainee Gas Company L.L.C., Rock Creek Ranch, Inc. and Lone Star
Land & Cattle Company.
 
     Craig G. Matthews has been a Director of the Company since 1993. Mr.
Matthews has been President and Chief Operating Officer of Brooklyn Union since
May 1996 and of KeySpan since September 1997, was Executive Vice President of
Brooklyn Union from 1994 to 1996, and was Executive Vice President and Chief
Financial Officer of Brooklyn Union from 1991 to 1994. Mr. Matthews joined
Brooklyn Union in 1965. He graduated from Rutgers University in 1965 with a
Bachelor's Degree in Civil Engineering, and acquired an M.S. Degree in
Industrial Management from Polytechnic University. Mr. Matthews is a member of
the Board of Directors for the Brooklyn Philharmonic, the Public Utilities
Reports, Inc., the Brooklyn Chamber of Commerce, Neighborhood Housing Services,
Greater Jamaica Development Corp., Regional Plan Association, Polytechnic
University, Prospect Park Alliance, the National and New York Advisory Board of
the Salvation Army and Inform. Mr. Matthews is the Treasurer of the Society of
Gas Lighters.
 
     James Q. Riordan has been a Director of the Company since 1996 and a
Director of KeySpan and its predecessor, Brooklyn Union, since 1991. Mr. Riordan
is the retired Vice Chairman and Chief Financial Officer of Mobil Corp. He
joined Mobil Corp. in 1957 as Tax Counsel and was named Director and Chief
Financial Officer in 1969. Mr. Riordan served as Vice Chairman of Mobil Corp.
from 1986 until his retirement in 1989. He joined Bekaert Corporation in 1989
and was elected its President, and served as President until his retirement in
1992. Mr. Riordan is a Director of Dow Jones & Co., Inc., Tri-Continental
Corporation and the Public Broadcasting Service; Director/Trustee of the mutual
funds in the Seligman Group of investment companies; Trustee for the Committee
for Economic Development and The Brooklyn Museum; and Member of the Policy
Council of the Tax Foundation.
 
     Lester H. Smith has been a Director of the Company since 1996. Mr. Smith is
Chairman of the Board and President of Smith Energy Company, an independent oil
and gas exploration company, and Chairman of the Board of Founders
International, Ltd., an international downhole drilling tool company. Mr. Smith
has been active in the energy business as an independent since 1973. He attended
the University of Oklahoma where he majored in finance. Mr. Smith is Chairman of
the Board of SG Interests, Inc., SG Methane Company, and Utah Coal and Lumber
Company, and a member of the Board of Directors, or equivalent governing body in
the case of partnerships or limited liability companies, of SG Interests I-V, SG
Gathering, Inc. and Gainee Gas Company, L.L.C.
 
     Donald C. Vaughn has been President, Chief Operating Officer and member of
the board of directors of Dresser Industries, Inc. ("Dresser") since 1996. Prior
to his appointment as President and Chief Operating Officer, Mr. Vaughn served
as Executive Vice President of Dresser, responsible for Dresser's Petroleum
Products and Services and Engineering Services Segment, from November 1995 to
December 1996; Senior Vice President of Operations of Dresser from January 1992
to November 1995; and Chairman, President and Chief Executive Officer of The
M.W. Kellogg Company from November 1983 to June 1996. Mr. Vaughn joined M.W.
Kellogg in 1958 and is a registered professional engineer in the State of Texas.
He has been recognized as a distinguished engineering alumnus of Virginia
Polytechnic Institute, from which he holds a B.S. degree in civil engineering.
Mr. Vaughn serves as a director on the boards of several Dresser joint venture
companies, including Dresser-Rand Company, Ingersoll-Dresser Pump Company and
Bredero-Shaw.
 
                                       61
<PAGE>   63
 
EXECUTIVE OFFICERS
 
     Set forth below is certain information concerning the executive officers of
the Company, including the business experience of each during the past five
years.
 
<TABLE>
<CAPTION>
                 NAME                   AGE                  POSITION
                 ----                   ---                  --------
<S>                                     <C>   <C>
James G. Floyd........................  61    President and Chief Executive Officer
                                              and Director
Randall J. Fleming....................  56    Senior Vice President -- Exploration
                                              and Production
Thomas W. Powers......................  53    Senior Vice President -- Business
                                                Development and Finance and
                                                Treasurer
Charles W. Adcock.....................  44    Vice President -- Project Development
Sammye L. Dees........................  62    Vice President -- Land
James F. Westmoreland.................  42    Vice President, Chief Accounting
                                              Officer, Comptroller and Secretary
</TABLE>
 
     Information regarding the business experience of James G. Floyd is set
forth above under the heading "Directors."
 
     Randall J. Fleming has been Senior Vice President -- Exploration and
Production of the Company since October 1995 and was Vice
President -- Exploration of the Company from 1986 to 1995. Mr. Fleming was Vice
President -- Geology of Seagull from 1981 to 1986 and was an exploration
geologist at Houston Oil and Minerals from 1976 to 1981. Prior to such time, Mr.
Fleming was an exploration geologist for Superior Oil Company and Sinclair Oil
Company. Mr. Fleming holds a B.A. and M.S. in geology from the University of
Alabama.
 
     Thomas W. Powers has been Senior Vice President -- Business Development and
Finance of the Company since October 1995 and Treasurer since May 1996. Mr.
Powers was General Manager of Diversification for Brooklyn Union from 1991 to
1995 and Executive Vice President and Chief Operating Officer of Fuel Resources
Inc. ("FRI"), a Brooklyn Union subsidiary, from 1986 to 1991. Prior to joining
Brooklyn Union, Mr. Powers was Manager of Corporate Development for Anglo
Energy. He holds a B.S. in Economics from Bowling Green University and an M.B.A.
from Long Island University.
 
     Charles W. Adcock has been Vice President -- Project Development of the
Company since 1996. Mr. Adcock held the same position with FRI, the Brooklyn
Union subsidiary that previously owned the Company's onshore properties, from
1993 to 1996. Prior to joining FRI, Mr. Adcock worked at NERCO Oil & Gas as
Reservoir Engineering Specialist. Prior to NERCO, he held various engineering
positions with Apache, ANR Production and Aminoil U.S.A. Mr. Adcock is a
Registered Professional Engineer in the State of Texas, and received his B.S. in
Civil Engineering from Texas A&M University and an M.B.A. from the University of
St. Thomas.
 
     Sammye L. Dees has been Vice President -- Land of the Company since 1986.
Ms. Dees was Vice President -- Land of Seagull from 1981 to 1986, and was Land
Manager, Offshore Division, of Houston Oil and Minerals from 1974 to 1981. Prior
to joining Houston Oil and Minerals, Ms. Dees worked for Allied Chemical
Corporation. Ms. Dees is a Certified Petroleum Landman and attended Stephen F.
Austin University.
 
     James F. Westmoreland has been Vice President, Chief Accounting Officer,
Comptroller and Secretary of the Company since October 1995 and was Vice
President and Comptroller of the Company from 1986 to 1995. Mr. Westmoreland was
supervisor of natural gas and oil accounting at Seagull from 1983 to 1986. Mr.
Westmoreland holds a B.B.A. in accounting from the University of Houston.
 
                                       62
<PAGE>   64
 
EMPLOYMENT AGREEMENTS
 
     Messrs. Floyd, Fleming, Powers, Westmoreland and Adcock entered into
employment agreements with the Company effective as of September 19, 1996,
pursuant to which they serve as executive officers of the Company.
 
     Such employment agreements provide for Messrs. Floyd, Fleming, Powers,
Westmoreland and Adcock to receive annual base salaries of $390,000, $250,000,
$160,000, $150,000 and $140,000, respectively. Under such agreements, Messrs.
Floyd, Fleming, Powers, Westmoreland and Adcock are entitled to annual incentive
bonuses of 70%, 60%, 55%, 55% and 55%, respectively, of base salary if the
Company meets financial targets established by the Board of Directors. In
addition, Messrs. Floyd, Fleming, Powers, Westmoreland and Adcock are entitled
to participate in such incentive compensation and other programs as are adopted
by the Company's Board of Directors, including the Company's 1996 Stock Option
Plan. The initial term of each employment agreement extends to the third
anniversary of the effective date of such agreement; provided, however, that the
term of each agreement is automatically extended one year on each anniversary
unless notice that the agreement will not be extended is given by either party
at least 60 days prior to such anniversary.
 
     Each of the employment agreements is subject to early termination by the
Company for cause or upon the death or disability of the employee and is subject
to early termination by the employee for any reason. If an employment agreement
is terminated without cause by the Company or with good reason (including
certain changes in control of the Company) by the employee, the Company is
obligated to pay such employee a lump-sum severance payment of 2.99 times the
employee's then current annual rate of total compensation. Based upon their
current annual rate of compensation, Messrs. Floyd, Fleming, Powers,
Westmoreland and Adcock would be entitled to lump sum severance payments of
$1,166,100, $747,500, $478,400, $448,500 and $418,600, respectively, if
terminated without cause or by the employee for good reason.
 
                              CERTAIN TRANSACTIONS
 
TRANSACTIONS BETWEEN THE COMPANY AND BROOKLYN UNION AND AFFILIATES
 
     The Company was incorporated in December 1985 to conduct certain of the
natural gas and oil exploration and development activities of Brooklyn Union.
The Company has focused since its inception primarily on the exploration and
development of high potential prospects in the Gulf of Mexico. Effective
February 29, 1996, Brooklyn Union implemented a reorganization of its
exploration and production assets by transferring to the Company certain onshore
producing properties and developed and undeveloped acreage not previously owned
by the Company. Brooklyn Union has advised the Company that it does not
currently intend to engage in the domestic exploration for or production of
natural gas and oil except through ownership of Common Stock of the Company. In
September of 1997, Brooklyn Union became a wholly owned subsidiary of KeySpan
Energy Corporation.
 
     Effective January 1, 1997, the Company entered into an agreement to sell to
a subsidiary of Brooklyn Union certain interests in onshore producing wells of
the Company that produce from formations that qualify for tax credits under
Section 29 of the Internal Revenue Code ("Section 29"). Section 29 provides for
a tax credit from non-conventional fuel sources such as oil produced from shale
and tar sands and natural gas produced from geopressured brine, Devonian shale,
coal seams and tight sands formations. Brooklyn Union acquired an economic
interest in wells that are qualified for the tax credits and in exchange, the
Company (i) retained a volumetric production payment and a net profits interest
of 100% in the properties, (ii) received a cash down payment of $1.4 million and
(iii) receives a quarterly payment of $0.75 for every dollar of tax credit
utilized. The Company manages and administers the daily operations of the
properties in exchange for an annual management fee of $100,000. At December 31,
1997, the balance sheet effect of this transaction was a $1.4 million reduction
to the full cost pool for the down payment. The income statement effect for the
year ended December 31, 1997 was a reduction to income tax expense of $1.2
million representing benefits received from the Section 29 tax credits.
 
                                       63
<PAGE>   65
 
     The Company was included in the consolidated federal income tax returns
filed by Brooklyn Union during all periods in which it was a wholly owned
subsidiary of Brooklyn Union ("Affiliation Years"). The Company and Brooklyn
Union are parties to an agreement (the "Tax Sharing Agreement") providing for
the manner of determining payments with respect to federal income tax
liabilities and benefits arising during the Affiliation Years. Under the Tax
Sharing Agreement, the Company paid to or received from Brooklyn Union an amount
equal to the Company's share of Brooklyn Union's consolidated federal income tax
liability, generally determined on a separate return basis, for the years ended
and the portion of 1996 preceding consummation of the IPO, and Brooklyn Union
paid the Company for any reduction in Brooklyn Union's consolidated federal
income tax liability resulting from utilization or deemed utilization of
deductions, losses, and credits arising in such periods which are attributable
to the Company, in each case net of any amounts theretofore paid or credited by
Brooklyn Union or the Company to the other with respect thereto. In the event
that Brooklyn Union's consolidated federal income tax liability for any
Affiliation Year is adjusted upon audit or otherwise, the Company will bear any
additional liability or receive any refund which is attributable to adjustments
of items of income, deduction, gain, loss or credit of the Company. Brooklyn
Union shall permit the Company to participate in any audits or litigation with
respect to the Affiliation Years, but Brooklyn Union will otherwise have
exclusive and sole responsibility and control over any such proceedings. As of
September 1996, the Company ceased to be included in the consolidated federal
income tax returns filed by Brooklyn Union.
 
     Under a Registration Rights Agreement entered into between the Company and
Brooklyn Union, the Company will file, upon the request of Brooklyn Union, a
registration statement under the Securities Act for the purpose of enabling
Brooklyn Union to offer and sell any securities of the Company which Brooklyn
Union may hold. Brooklyn Union may exercise these rights at any time. The
Company will bear the costs of any registered offering, except that Brooklyn
Union will pay any underwriting commissions relating to any such offering, any
transfer taxes and any costs of complying with foreign securities laws at
Brooklyn Union's request, and each will pay for its counsel and accountants. The
Company has the right to require Brooklyn Union to delay any exercise by
Brooklyn Union of its rights to require registration and other actions for a
period of up to 180 days if, in the judgment of the Company, the Company or any
offering by the Company then being conducted or about to be conducted would be
adversely affected. The Company has also granted Brooklyn Union the right to
include its securities in certain registration statements covering offerings by
the Company, and the Company will pay all costs of such offerings other than
underwriting commissions and transfer taxes attributable to the securities sold
on behalf of Brooklyn Union. The Company has agreed to indemnify Brooklyn Union,
its officers, directors, agents, any underwriter, and each person controlling
any of the foregoing, against certain liabilities under the Securities Act or
the securities laws of any state or country in which securities of the Company
are sold.
 
     The Company reimburses Brooklyn Union for certain general and
administrative costs. During the years ended December 31, 1995, 1996 and 1997,
the Company paid Brooklyn Union $0.7 million, $0.6 million and $0.1 million,
respectively, in general and administrative reimbursements.
 
TRANSACTIONS BETWEEN THE COMPANY AND MANAGEMENT
 
     The Company entered into new employment agreements with Messrs. Floyd,
Fleming, Powers, Adcock and Westmoreland at the time of the IPO. These
employment agreements replaced the Company's previous employment agreements with
such officers.
 
     The Company's previous employment agreement with Mr. Floyd, its President
and Chief Executive officer, provided Mr. Floyd with the option to obtain up to
a 5% working interest in certain exploration prospects of the Company,
exercisable prior to the commencement of drilling of the initial well on any
such prospect. During 1995 and 1996, affiliates of Mr. Floyd obtained a 5%
working interest in 144 wells (including 142 wells in the Charco field) operated
by the Company pursuant to such agreement. During 1995, 1996 and 1997,
affiliates of the Company's President and Chief Executive Officer paid $0.7
million, $1.4 million and $3.3 million, respectively, in expenses attributable
to working interests owned in properties operated by the Company, and received
$0.9 million, $1.6 million and $3.9 million, respectively, in distributions
attributable to such working interests. The termination of the Company's
previous employment agreement with Mr. Floyd at
                                       64
<PAGE>   66
 
the time of the IPO terminated Mr. Floyd's right to obtain working interests on
any further properties, but did not affect working interests in properties of
the Company acquired by Mr. Floyd or his affiliates prior to the date of
termination.
 
     The Company loaned Mr. Floyd the $3.1 million purchase price for his
purchase of a 5% working interest in the properties purchased by the Company in
the TransTexas Acquisition. In addition, the Company has agreed to loan Mr.
Floyd, on a revolving basis, the amounts required to fund the expenses
attributable to Mr. Floyd's working interest. Mr. Floyd is required to repay
amounts owed under the loan in the amount of 65% of all distributions received
by Mr. Floyd in respect of such working interest, as distributions are received.
Amounts outstanding under such loan bear interest at an interest rate equal to
the Company's cost of borrowing under the Credit Facility. Mr. Floyd's
obligations under the agreement are secured by a pledge of his working interest
in, and the production from, such properties. As of December 31, 1997, the
outstanding balance owed by Mr. Floyd under the agreement was $3.7 million and
the loan will mature on July 2, 2006.
 
     The Company's previous employment agreement with Mr. Floyd also provided
for the assignment to Mr. Floyd of a 2% net profits interest in all exploration
prospects of the Company at the time such properties were acquired by the
Company. The Company assigned a 2% net profits interest to Mr. Floyd in two
properties acquired by the Company in 1995. No assignments were made in 1996 or
1997. The termination of the Company's previous employment agreement with Mr.
Floyd at the time of the IPO terminated Mr. Floyd's right to receive any further
assignments but did not affect net profits interests in properties of the
Company assigned to Mr. Floyd prior to the date of termination.
 
     The Company's previous employment agreement with Mr. Floyd also provided
for the assignment to certain key employees designated by Mr. Floyd of
overriding royalty interests equivalent to a four percent net revenue interest
in certain properties of the Company at the time such properties were acquired
by the Company. The Company assigned overriding royalty interests to Mr.
Fleming, Ms. Dees and Mr. Westmoreland in two properties acquired by the Company
in 1995. No assignments were made in 1996 or 1997. The termination of the
Company's previous employment agreement with Mr. Floyd at the time of the IPO
terminated all rights to any further assignments but did not affect overriding
royalty interests in properties of the Company assigned to key employees prior
to the date of termination.
 
     The Company's previous employment agreement with Mr. Floyd also provided
for the assignment of a 6.75% after program-payout working interest in the
leases upon which the Company began drilling an exploratory well (whether or not
successful) during a calendar year. As of the date of this Prospectus, Mr. Floyd
had not received any distributions under this arrangement. The termination of
the Company's previous employment agreement with Mr. Floyd at the time of the
IPO terminated Mr. Floyd's right to receive any further assignments but did not
affect after program-payout working interests on properties of the Company
assigned to Mr. Floyd prior to the date of termination. On September 19, 1996,
Mr. Floyd exchanged certain after program-payout working interests received
under his previous employment agreement for 145,161 shares of Common Stock with
a value of approximately $2.3 million.
 
SOXCO ACQUISITION
 
     On September 25, 1996, the Company acquired substantially all of the
natural gas and oil properties and related assets of Soxco in the Soxco
Acquisition. Under an agreement with Soxco, Lester H. Smith had received a 1.25%
net profits interest, proportionately reduced for Soxco's interest, in all
properties in which Soxco had participated. Upon the sale by Soxco of its
properties, Mr. Smith exercised his right to sell all such net profits interests
on the same economic terms to be received by Soxco in the transaction. Mr. Smith
received approximately $90,000 in cash, 13,553 initial shares of Common Stock
and the right to receive additional shares of Common Stock with a value of
approximately $100,000 upon payment of the minimum deferred purchase price of
the Soxco Acquisition. The Company delivered 5,674 shares of Common Stock in
satisfaction of Mr. Smith's right to receive such additional shares as part of
its payment of the deferred purchase price of the Soxco Acquisition in the first
quarter of 1998. In connection with the sale by Soxco of its properties, the
Company granted three demand and certain piggyback registration rights with
respect to the shares of Common Stock issued in connection with the transaction.
Such registration rights are subject to certain conditions.
                                       65
<PAGE>   67
 
                            DESCRIPTION OF THE NOTES
 
GENERAL
 
     The Exchange Notes will be issued, and the Old Notes were issued, pursuant
to an Indenture (the "Indenture") between the Company and The Bank of New York,
as trustee (the "Trustee"), in a private transaction that is not subject to the
registration requirements of the Securities Act. See "Notice to Investors." The
terms of the Notes include those stated in the Indenture and those made part of
the Indenture by reference to the Trust Indenture Act of 1939, as amended (the
"Trust Indenture Act"). The Notes are subject to all such terms, and prospective
Holders of Notes are referred to the Indenture and the Trust Indenture Act for a
statement of such terms. The following summary of certain provisions of the
Indenture does not purport to be complete and is qualified in its entirety by
reference to the Indenture, a copy of which has been filed as an exhibit to the
Registration Statement of which this Prospectus is a part, and the definitions
therein of certain terms used below. Definitions of certain capitalized terms
used in the Indenture and in the following summary are set forth below under
"-- Certain Definitions." For purposes of this summary, the term "Company"
refers only to The Houston Exploration Company and not to any of its
Subsidiaries.
 
     The Exchange Notes will be issued solely in exchange for an equal principal
amount of Old Notes pursuant to the Exchange Offer. The form and terms of the
Exchange Notes will be identical in all material respects to the form and terms
of the Old Notes except that the offering of the Exchange Notes has been
registered under the Securities Act, and the Exchange Notes will therefore not
be subject to transfer restrictions, registration rights and certain provisions
relating to the payment of Liquidated Damages under certain circumstances. See
"-- Registration Rights; Liquidated Damages."
 
     The Old Notes and the Exchange Notes will constitute a single series of
debt securities under the Indenture. If the Exchange Offer is consummated,
holders of Old Notes who do not exchange their Old Notes for Exchange Notes will
vote together with holders of the Exchange Notes for all relevant purposes under
the Indenture. In that regard, the Indenture requires that certain actions by
the holders thereunder (including following an Event of Default) must be taken,
and certain rights must be exercised, by specified minimum percentages of the
aggregate principal amount of the outstanding securities issued under the
Indenture. In determining whether holders of the requisite percentage in
principal amount have given any notice, consent or waiver or taken any other
action permitted under the Indenture, any Old Notes that remain outstanding
after the Exchange Offer will be aggregated with the Exchange Notes, and the
holders of such Old Notes and the Exchange Notes will vote together as a single
series for all such purposes. Accordingly, all references herein to specified
percentages in aggregate principal amount of the outstanding Notes shall be
deemed to mean, at any time after the Exchange Offer is consummated, such
percentages in aggregate principal amount of the Old Notes and the Exchange
Notes then outstanding.
 
     The Notes are general unsecured obligations of the Company and are
subordinated in right of payment to Senior Debt. See "Risk
Factors -- Subordination of Notes."
 
     Restrictions in the Indenture on the ability of the Company and its
Restricted Subsidiaries to incur additional Indebtedness, to make Asset Sales,
to enter into transactions with Affiliates and to enter into mergers,
consolidations or sales of all or substantially all of its assets, may make more
difficult or discourage a takeover of the Company, whether favored or opposed by
the management of the Company. The Indenture may not afford holders of Notes
protection in all circumstances from the adverse aspects of a leveraged
transaction, reorganization, restructuring, merger or similar transaction.
 
     As of the date hereof, the Company has one Subsidiary, which constitutes a
Restricted Subsidiary for the purposes of the Indenture. Under certain
circumstances, the Company will be able to designate current and future
Subsidiaries as Unrestricted Subsidiaries. Unrestricted Subsidiaries will not be
subject to many of the restrictive covenants set forth in the Indenture.
 
                                       66
<PAGE>   68
 
PRINCIPAL, MATURITY AND INTEREST
 
     The Notes are limited in aggregate principal amount to $100.0 million and
will mature on January 1, 2008. Interest on the Notes accrues at the rate of
8 5/8% per annum and is payable semi-annually in arrears on January 1 and July
1, commencing on July 1, 1998, to Holders of record on the immediately preceding
December 15 and June 15. Interest on the Notes will accrue from the most recent
date to which interest has been paid or, if no interest has been paid, from the
date of original issuance, March 2, 1998. Interest will be computed on the basis
of a 360-day year comprised of twelve 30-day months. Principal, premium, if any,
Liquidated Damages, if any, and interest on the Notes will be payable at the
office or agency of the Company maintained for such purpose within the City and
State of New York or, at the option of the Company, payment of Liquidated
Damages, if any, or interest may be made by check mailed to the Holders of the
Notes at their respective addresses set forth in the register of Holders of
Notes; provided that all payments with respect to Global Notes and Certificated
Securities the Holders of whom have given wire transfer instructions to the
Company and its paying agent prior to the applicable record date for such
payment will be required to be made by wire transfer of immediately available
funds to the accounts specified by the Holders thereof. Until otherwise
designated by the Company, the Company's office or agency will be the office of
the Trustee maintained for such purpose. The Company may change such office or
agency without prior notice to Holders of the Notes, and any of its Subsidiaries
may act as Paying Agent or Registrar. The Notes will be issued in denominations
of $1,000 and integral multiples thereof.
 
OPTIONAL REDEMPTION
 
     Except as set forth below, the Notes will not be redeemable at the
Company's option prior to January 1, 2003. Thereafter, the Notes will be subject
to redemption for cash at the option of the Company, in whole or in part, upon
not less than 30 nor more than 60 days' notice to each Holder of Notes to be
redeemed, at the following redemption prices (expressed as percentages of
principal amount thereof) if redeemed during the 12-month period beginning on
January 1 of each of the years indicated below, in each case together with any
accrued and unpaid interest and Liquidated Damages, if any, thereon to the
applicable redemption date:
 
<TABLE>
<CAPTION>
                       YEAR                         PERCENTAGE
                       ----                         ----------
<S>                                                 <C>
2003..............................................   104.313%
2004..............................................   102.875%
2005..............................................   101.438%
2006 and thereafter...............................   100.000%
</TABLE>
 
     Notwithstanding the foregoing, at any time on or before January 1, 2001,
the Company may (but will not have the obligation to) redeem for cash up to 35%
of the original aggregate principal amount of the Notes at a redemption price of
108.625% of the principal amount thereof, in each case plus any accrued and
unpaid interest and Liquidated Damages, if any, thereon to the redemption date,
with the net proceeds of an Equity Offering; provided that at least 65% of the
original aggregate principal amount of the Notes remains outstanding immediately
after the occurrence of such redemption; and provided, further, that such
redemption will occur within 90 days of the date of the closing of such Equity
Offering.
 
     If less than all of the Notes are to be redeemed at any time, selection of
Notes for redemption will be made by the Trustee in compliance with the
requirements of the principal national securities exchange, if any, on which the
Notes are listed, or, if the Notes are not so listed, on a pro rata basis, by
lot or by such method as the Trustee will deem fair and appropriate; provided
that no Notes of $1,000 or less will be redeemed in part. Notices of redemption
will be mailed by first class mail at least 30 but not more than 60 days before
the redemption date to each Holder of Notes to be redeemed at its registered
address. If any Note is to be redeemed in part only, the notice of redemption
that relates to such Note will state the portion of the principal amount thereof
to be redeemed. A new Note in principal amount equal to the unredeemed portion
thereof will be issued in the name of the Holder thereof upon cancellation of
the original Note. On and after the redemption date, interest will cease to
accrue on Notes or portions of them called for redemption unless the Company
defaults in the payment thereof.
 
                                       67
<PAGE>   69
 
RANKING AND SUBORDINATION
 
     The payment of principal of, premium, if any, and interest on, the Notes
and any other payment obligations of the Company in respect of the Notes
(including any obligation to repurchase the Notes) is subordinated in certain
circumstances in right of payment, as set forth in the Indenture, to the prior
payment in full in cash of all Senior Debt, whether outstanding on the date of
the Indenture or thereafter incurred.
 
     Upon any payment or distribution of property or securities to creditors of
the Company in a liquidation or dissolution of the Company or in a bankruptcy,
reorganization, insolvency, receivership or similar proceeding relating to the
Company or its property, or in an assignment for the benefit of creditors or any
marshalling of the Company's assets and liabilities, the holders of Senior Debt
will be entitled to receive payment in full of all Obligations due in respect of
such Senior Debt (including interest after the commencement of any such
proceeding at the rate specified in the applicable Senior Debt, whether or not a
claim for such interest would be allowed in a proceeding) before the Holders of
the Notes will be entitled to receive any payment with respect to the Notes, and
until all Obligations with respect to Senior Debt are paid in full, any
distribution to which the Holders of the Notes would be entitled shall be made
to the holders of Senior Debt (except that Holders of the Notes may receive
payments made from the trust described under "-- Legal Defeasance and Covenant
Defeasance").
 
     The Company also may not make any payment (whether by redemption, purchase,
retirement, defeasance or otherwise) upon or in respect of the Notes (except
from the trust described under "-- Legal Defeasance and Covenant Defeasance") if
(i) a default in the payment of the principal of, premium, if any, or interest
on Designated Senior Debt occurs ("payment default") or (ii) any other default
occurs and is continuing with respect to Designated Senior Debt that permits, or
with the giving of notice or passage of time or both (unless cured or waived)
will permit, holders of the Designated Senior Debt as to which such default
relates to accelerate its maturity ("non-payment default") and (solely with
respect to this clause (ii)) the Trustee receives a notice of such default (a
"Payment Blockage Notice") from the Company or the holders of any Designated
Senior Debt. Cash payments on the Notes shall be resumed (a) in the case of a
payment default, upon the date on which such default is cured or waived and (b)
in case of a nonpayment default, the earlier of the date on which such
nonpayment default is cured or waived or 179 days after the date on which the
applicable Payment Blockage Notice is received, unless the maturity of any
Designated Senior Debt has been accelerated or a default of the type described
in clause (viii) under the caption "Events of Default and Remedies" has occurred
and is continuing. No new period of payment blockage may be commenced unless and
until 360 days have elapsed since the date of commencement of the payment
blockage period resulting from the immediately prior Payment Blockage Notice. No
nonpayment default in respect of Designated Senior Debt that existed or was
continuing on the date of delivery of any Payment Blockage Notice to the Trustee
shall be, or be made, the basis for a subsequent Payment Blockage Notice unless
such default shall have been cured or waived for a period of no less than 90
days.
 
     The Indenture further requires that the Company promptly notify holders of
Senior Debt if payment of the Notes is accelerated because of an Event of
Default.
 
     As a result of the subordination provisions described above, in the event
of a liquidation or insolvency of the Company, Holders of the Notes may recover
less ratably than creditors of the Company who are holders of Senior Debt. After
giving effect to the sale of the Notes and the application of the net proceeds
therefrom, $15.4 million of Senior Debt, $42.4 million of trade payables and
other accrued liabilities and no senior subordinated debt other than the Notes
would have been outstanding as of December 31, 1997. The Indenture limits,
subject to certain financial tests, the amount of additional Indebtedness,
including Senior Debt, that the Company and its Subsidiaries can incur. See "--
Certain Covenants -- Incurrence of Indebtedness and Issuance of Preferred
Stock."
 
MANDATORY REDEMPTION
 
     Except as set forth below under "-- Repurchase at the Option of Holders",
the Company is not required to make any mandatory redemption, purchase or
sinking fund payments with respect to the Notes prior to the maturity date.
                                       68
<PAGE>   70
 
REPURCHASE AT THE OPTION OF HOLDERS
 
  Change of Control
 
     The Indenture provides that upon the occurrence of a Change of Control,
each Holder of Notes will have the right to require the Company to repurchase
all or any part (equal to $1,000 or an integral multiple thereof) of such
Holder's Notes pursuant to the offer described below (the "Change of Control
Offer") at an offer price in cash equal to 101% of the aggregate principal
amount thereof plus accrued and unpaid interest and Liquidated Damages, if any,
thereon to the date of purchase (the "Change of Control Payment"). Within 30
days following any Change of Control, the Company will mail a notice to each
Holder describing the transaction or transactions that constitute the Change of
Control and offering to repurchase the Notes pursuant to the procedures required
by the Indenture and described in such notice. The Company will comply with the
requirements of Rule 14e-1 under the Exchange Act and any other securities laws
and regulations thereunder to the extent such laws and regulations are
applicable in connection with the repurchase of the Notes as a result of a
Change of Control.
 
     The Change of Control Offer will remain open for a period of 20 Business
Days following its commencement and no longer, except to the extent that a
longer period is required by applicable law (the "Change of Control Offer
Period"). No later than five Business Days after the termination of the Offer
Period (the "Change of Control Purchase Date"), the Company will purchase all
Notes validly tendered and not properly withdrawn pursuant to the Change of
Control Offer. Payment for any Notes so purchased will be made in the same
manner as interest payments are made on the Notes.
 
     "Change of Control" means the occurrence of any of the following: (i) any
"Person" (as such term is used in Sections 13(d) and 14(d) of the Exchange Act),
other than the Permitted Holders, is or becomes the beneficial owner (as defined
in Rules 13d-3 and 13d-5 under the Exchange Act, except that a Person shall be
deemed to have a "beneficial ownership" of all shares that any such Person has
the right to acquire, whether such right is exercisable immediately or only
after the passage of time), directly or indirectly, of 35% or more of the total
voting power of the Voting Stock of the Company, provided however that the
Permitted Holders beneficially own (as defined in Rules 13d-3 and 13d-5 under
the Exchange Act), directly or indirectly, in the aggregate a lesser percentage
of the total voting power of the Voting Stock of the Company than such other
person (for purposes of this definition, such other person shall be deemed to
beneficially own any Voting Stock of a specified corporation held by a parent
corporation, if such other person is the beneficial owner (as defined above),
directly or indirectly, or more than 35% of the voting power of the Voting Stock
of such parent corporation and the Permitted Holders beneficially own (as
defined in this proviso), directly or indirectly, in the aggregate a lesser
percentage of the Voting Stock of such parent corporation); (ii) the sale,
lease, transfer, conveyance or other disposition (other than by way of merger or
consolidation), in one or a series of related transactions, of all or
substantially all of the assets of the Company and its Restricted Subsidiaries
taken as a whole to any "Person" or group of related Persons (a "Group") (as
such term is used in Sections 13(d) and 14(d) of the Exchange Act) other than
the Permitted Holders; (iii) the adoption of a plan relating to the liquidation
or dissolution of the Company; or (iv) during any period of two consecutive
years, individuals who at the beginning of such period constituted the Board of
Directors (together with any new directors whose election by such Board of
Directors or whose nomination for election by the shareholders of the Company
was approved by a vote of a majority of the directors of the Company then still
in office who were either directors at the beginning of such period or whose
election or nomination for election was previously so approved) cease for any
reason to constitute a majority of the Board of Directors then in office.
 
     "Permitted Holders" means THEC Holding Corp., Brooklyn Union, KeySpan and
(to the extent it has consummated a merger, consolidation or other business
combination transaction with KeySpan) Long Island Lighting Company, and any
successor or Affiliate of any such Person.
 
     If the Change of Control Purchase Date is on or after an interest record
date and on or before the related interest payment date, any accrued and unpaid
interest and Liquidated Damages, if any, will be paid to the Person in whose
name a Note is registered at the close of business on such record date, and no
additional interest will be payable to Holders who tender Notes pursuant to the
Change of Control Offer.
 
                                       69
<PAGE>   71
 
     On the Change of Control Purchase Date, the Company will, to the extent
lawful, (i) accept for payment all Notes or portions thereof validly tendered
and not properly withdrawn pursuant to the Change of Control Offer, (ii) deposit
with the Paying Agent an amount equal to the Change of Control Payment in
respect of all Notes or portions thereof so validly tendered and not properly
withdrawn and (iii) deliver or cause to be delivered to the Trustee the Notes so
accepted together with an Officers' Certificate stating the aggregate principal
amount of Notes or portions thereof being purchased by the Company. The Paying
Agent will promptly mail to each Holder of the Notes so validly tendered and not
properly withdrawn the Change of Control Payment for such Notes and the Trustee
will promptly authenticate and mail (or cause to be transferred by book entry)
to each Holder a new Note equal in principal amount to any unpurchased portion
of the Notes surrendered, if any; provided that each such new Note will be in a
principal amount of $1,000 or an integral multiple thereof. The Indenture
provides that, prior to complying with the provisions of this covenant, but in
any event within 30 days following a Change of Control, the Company will either
repay all outstanding Senior Debt or obtain the requisite consents, if any,
under all agreements governing outstanding Senior Debt to permit the repurchase
of the Notes required by this covenant. The Company will publicly announce the
results of the Change of Control Offer on the Change of Control Purchase Date.
 
     Except as described above, the Indenture does not contain provisions that
permit the Holders of Notes to require the Company to redeem the Notes in the
event of a takeover, recapitalization or similar restructuring, including an
issuer recapitalization or similar transaction with management. In addition, the
existence of the Holder's right to require the Company to repurchase such
Holder's Notes upon the occurrence of a Change of Control may or may not deter a
third party from seeking to acquire the Company in a transaction that would
constitute a Change of Control.
 
     The Company's ability to repurchase Notes pursuant to a Change of Control
Offer may be limited by a number of factors. The Credit Agreement provides that
certain change of control events with respect to the Company would constitute a
default thereunder permitting the lending parties thereto to accelerate the
Indebtedness thereunder. In addition, certain events that may obligate the
Company to offer to repay all outstanding obligations under the Credit Agreement
may not constitute a Change of Control under the Indenture. However, the Company
may not have sufficient resources to repay Indebtedness under the Credit
Agreement and the Company may not have sufficient resources to repurchase
tendered Notes. Furthermore, any future credit agreements or other agreements
relating to Senior Debt to which the Company may become a party may contain
similar restrictions and provisions. In the event a Change of Control occurs at
a time when the Company is directly or indirectly prohibited from purchasing
Notes, the Company could seek the consent of its lenders to the purchase of
Notes or could attempt to refinance the borrowings that contain such
prohibition. If the Company does not obtain such a consent or repay such
borrowings, the purchase of Notes will remain prohibited. The failure by the
Company to purchase tendered Notes may constitute a breach of the Indenture
which would, in turn, constitute a default under the Credit Agreement and could
lead to the acceleration of the indebtedness thereunder.
 
     The definition of Change of Control includes a phrase relating to the sale,
lease or transfer of "all or substantially all" of the assets of the Company and
its Restricted Subsidiaries, taken as a whole. Although there is a developing
body of case law interpreting the phrase "substantially all," there is no
precise definition of the phrase under applicable law. Accordingly, the ability
of a Holder of Notes to require the Company to repurchase such Notes as a result
of a sale, lease or transfer of less than all of the assets of the Company and
its Restricted Subsidiaries taken as a whole to another Person or group may be
uncertain.
 
  Asset Sales
 
     The Indenture provides that the Company will not, and will not permit any
of its Restricted Subsidiaries to, consummate an Asset Sale unless (i) the
Company (or the Restricted Subsidiary, as the case may be) receives
consideration at the time of such Asset Sale at least equal to the fair market
value of the assets or Equity Interests sold or otherwise disposed of (evidenced
by a resolution of the Board of Directors of such entity set forth in an
Officers' Certificate delivered to the Trustee) and (ii) at least 75% of the
consideration therefor received by the Company or such Restricted Subsidiary
from such Asset Sale, plus all other Asset Sales since the date of the
Indenture, on a cumulative basis, is in the form of cash, Cash Equivalents,
                                       70
<PAGE>   72
 
properties and capital assets to be used by the Company or any Restricted
Subsidiary in the Oil and Gas Business or oil and gas properties owned or held
by another Person which are to be used in the Oil and Gas Business of the
Company or its Restricted Subsidiaries, or any combination thereof (collectively
the "Cash Consideration"); provided that the amount of (x) any liabilities (as
shown on the Company's or such Restricted Subsidiary's most recent balance
sheet) of the Company or any Restricted Subsidiary (other than contingent
liabilities and liabilities that are by their terms subordinated to the Notes or
any Subsidiary Guarantee) that are assumed by the transferee of any such assets
pursuant to a customary novation agreement that releases the Company or such
Restricted Subsidiary from further liability and (y) any non Cash Consideration
received by the Company or any such Restricted Subsidiary from such transferee
that are converted into cash by the Company or such Restricted Subsidiary within
90 days after such Asset Sale, shall be deemed to be cash for purposes of this
provision to the extent of the cash received.
 
     Within 360 days after the receipt of any Net Proceeds from an Asset Sale,
the Company (or the Restricted Subsidiary, as applicable) may apply, or enter
into binding contracts (subject only to obtaining required governmental
approvals) irrevocably committing the Company or such Restricted Subsidiary to
apply, such Net Proceeds to an investment in another business, the making of a
capital expenditure or the acquisition of other tangible assets, in each case in
the Oil and Gas Business, or the Company (or the Restricted Subsidiary, as
applicable) may apply such Net Proceeds to the permanent reduction of Senior
Debt. Any Net Proceeds from Asset Sales that are not applied or invested or
committed to be applied or invested, as provided in the preceding sentence of
this paragraph will be deemed to constitute "Excess Proceeds." On the 361st day
after an Asset Sale, if the aggregate amount of Excess Proceeds exceeds $10.0
million, the Company will be required to make an offer to all Holders of Notes
and, to the extent required by the terms thereof, to all holders or lenders of
Pari Passu Indebtedness (an "Asset Sale Offer") to purchase the maximum
principal amount of Notes and any such Pari Passu Indebtedness to which the
asset sale offer applies that may be purchased out of the Excess Proceeds, at an
offer price in cash in an amount equal to 100% of the principal amount thereof
plus accrued and unpaid interest and, with respect to the Notes or similar
securities, Liquidated Damages or comparable amounts in the case of similar
securities, if any, thereon to the date of purchase, in accordance with the
procedures set forth in the Indenture or the agreements governing the Pari Passu
Indebtedness, as applicable. To the extent that the aggregate amount of Notes
and Pari Passu Indebtedness so validly tendered and not properly withdrawn
pursuant to an Asset Sale Offer is less than the Excess Proceeds, the Company
may use any remaining Excess Proceeds for general corporate purposes. If the
aggregate principal amount of Notes surrendered by Holders thereof and other
Pari Passu Indebtedness surrendered by holders or lenders thereof, collectively,
exceeds the amount of Excess Proceeds, the Trustee shall select the Notes and
Pari Passu Indebtedness to be purchased on a pro rata basis on the basis of the
aggregate principal amount of tendered Notes and Pari Passu Indebtedness. Upon
completion of such Asset Sale Offer, the amount of Excess Proceeds shall be
reset at zero.
 
     The Asset Sale Offer will remain open for a period of 20 Business Days
following its commencement and no longer, except to the extent that a longer
period is required by applicable law (the "Asset Sale Offer Period"). No later
than five Business Days after the termination of the Asset Sale Offer Period
(the "Asset Sale Purchase Date"), the Company will purchase the principal amount
of Notes and Pari Passu Indebtedness required to be purchased pursuant to this
covenant (the "Asset Sale Offer Amount") or, if less than the Asset Sale Offer
Amount has been so validly tendered, all Notes and Pari Passu Indebtedness
validly tendered in response to the Asset Sale Offer. Payment for any Notes and
Pari Passu Indebtedness so purchased will be made in the same manner as interest
payments are made on the Notes and Pari Passu Indebtedness, respectively.
 
     If the Asset Sale Purchase Date is on or after an interest record date and
on or before the related interest payment date, any accrued and unpaid interest
and Liquidated Damages will be paid to the Person in whose name a Note is
registered at the close of business on such record date, and no additional
interest will be payable to Holders who tender Notes pursuant to the Asset Sale
Offer.
 
     On or before the Asset Sale Purchase Date, the Company will, to the extent
lawful, accept for payment, on a pro rata basis to the extent necessary, the
Asset Sale Offer Amount of Notes and Pari Passu Indebtedness or portions thereof
so validly tendered and not properly withdrawn pursuant to the Asset Sale Offer,
or if less
                                       71
<PAGE>   73
 
than the Asset Sale Offer Amount has been validly tendered and not properly
withdrawn, all Notes and Pari Passu Indebtedness so validly tendered and not
properly withdrawn. The Company will deliver to the Trustee an Officers'
Certificate stating that such Notes or portions thereof were accepted for
payment by the Company in accordance with the terms of this covenant and, in
addition, the Company will deliver all certificates and notices required, if
any, by the agreements governing the Pari Passu Indebtedness. The Company, the
Depositary or the Paying Agent, as the case may be, will promptly (but in any
case not later than five days after the Asset Sale Purchase Date) mail or
deliver to each tendering Holder of Notes or holder or lender of Pari Passu
Indebtedness, as the case may be, an amount equal to the purchase price of the
Notes or Pari Passu Indebtedness so validly tendered and not properly withdrawn
by such Holder or lender, as the case may be, and accepted by the Company for
purchase, and the Company will promptly issue a new Note, and the Trustee, upon
delivery of an Officers' Certificate from the Company will authenticate and mail
or deliver such new Note to such Holder, in a principal amount equal to any
unpurchased portion of the Note surrendered. In addition, the Company will take
any and all other actions required by the agreements governing the Pari Passu
Indebtedness. Any Note not so accepted will be promptly mailed or delivered by
the Company to the Holder thereof. The Company will publicly announce the
results of the Asset Sale Offer on the Asset Sale Purchase Date.
 
     The Company will comply with the requirements of Rule 14e-1 under the
Exchange Act and any other securities laws and regulations thereunder to the
extent such laws and regulations are applicable in connection with the
repurchase of the Notes pursuant to any Asset Sale Offer.
 
     The Credit Agreement provides that certain change of control events with
respect to the Company would constitute a default thereunder. Any future credit
agreements or other agreements relating to Senior Debt to which the Company
becomes a party may contain similar provisions or may contain restrictions on
the Company's ability to purchase Notes. In the event a Change of Control or an
Asset Sale Offer occurs at a time when the Company is prohibited from purchasing
the Notes by the terms of such agreements relating to other Senior Debt, the
Company could seek the consent of its lenders to the purchase or could attempt
to refinance the borrowings that contain such prohibition. If the Company does
not obtain such a consent or repay such borrowings, the Company may remain
prohibited from purchasing the Notes. In such case, the Company's failure to
purchase tendered Notes would constitute an Event of Default under the Indenture
which may, in turn, constitute a default under such other agreements. In such
circumstances, the subordination provisions in the Indenture would restrict
payments to the Holders of the Notes.
 
CERTAIN COVENANTS
 
  Restricted Payments
 
     The Indenture provides that the Company will not, and will not permit any
of its Restricted Subsidiaries to, directly or indirectly: (i) declare or pay
any dividend or make any distribution on account of the Company's or any of its
Restricted Subsidiaries' Equity Interests (including, without limitation, any
payment in connection with any merger or consolidation involving the Company)
(other than dividends or distributions payable in Equity Interests (other than
Disqualified Stock) of the Company); (ii) purchase, redeem or otherwise acquire
or retire for value any Equity Interests of the Company or any Restricted
Subsidiary of the Company; (iii) prepay, purchase, redeem, defease or otherwise
acquire or retire for value any Indebtedness that is subordinated to the Notes,
except a scheduled repayment of principal or a payment of principal at stated
maturity; or (iv) make any Restricted Investment (all such payments and other
actions set forth in clauses (i) through (iv) above being collectively referred
to as "Restricted Payments"), unless, at the time of and after giving effect to
such Restricted Payment:
 
          (a) no Default or Event of Default shall have occurred and be
     continuing or would occur as a consequence thereof;
 
          (b) the Company would, at the time of such Restricted Payment and
     after giving pro forma effect thereto as if such Restricted Payment had
     been made at the beginning of the applicable four-quarter period, have been
     permitted to incur at least $1.00 of additional Indebtedness pursuant to
     the Fixed
 
                                       72
<PAGE>   74
 
     Charge Coverage Ratio test set forth in the first paragraph of the covenant
     described under "-- Incurrence of Indebtedness and Issuance of Preferred
     Stock"; and
 
          (c) such Restricted Payment, together with the aggregate of all other
     Restricted Payments made by the Company and its Restricted Subsidiaries
     after the date of the Indenture, does not exceed the sum of, without
     duplication, (i) 50% of the Consolidated Net Income of the Company for the
     period (taken as one accounting period) from the beginning of the first
     fiscal quarter commencing after the date of the Indenture to the end of the
     Company's most recently ended fiscal quarter for which internal financial
     statements are available at the time of such Restricted Payment (or, if
     such Consolidated Net Income for such period is a deficit or loss, less
     100% of such deficit or loss), plus (ii) to the extent not included in the
     amount described in clause (i) above, 100% of the aggregate net cash
     proceeds and the fair market value of marketable securities (as determined
     in good faith by the Company) received after the date of the Indenture by
     the Company from the issue or sale of, or from additional capital
     contributions in respect of, Equity Interests of the Company (but excluding
     cash proceeds and marketable securities received from the sale of Equity
     Interests to members of management or directors of the Company and its
     Restricted Subsidiaries after the Issue Date to the extent such amounts
     have been applied to make Restricted Payments in accordance with clause
     (vi) of the next succeeding paragraph) or of debt securities of the Company
     that have been converted into or exchanged for Equity Interests of the
     Company (other than Equity Interests (or debt securities) sold to a
     Subsidiary of the Company and other than Disqualified Stock or debt
     securities that have been converted into or exchanged for Disqualified
     Stock), plus (iii) to the extent that any Restricted Investment that was
     made after the date of the Indenture is sold to an unaffiliated purchaser
     for cash or marketable securities or otherwise liquidated or repaid for
     cash or marketable securities, the lesser of the cash proceeds and/or the
     fair market value of such marketable securities (as determined in good
     faith by the Company), as the case may be, and the amount of the Restricted
     Investment, which amount was included in the calculation of the amount of
     Restricted Payments, plus (iv) the amount equal to the net reduction in
     Investments in Unrestricted Subsidiaries resulting from (A) payments of
     dividends or interest or other transfers of assets to the Company or any
     Restricted Subsidiary from Unrestricted Subsidiaries, (B) the redesignation
     of Unrestricted Subsidiaries as Restricted Subsidiaries or (C) the receipt
     of proceeds by the Company or any Restricted Subsidiary from the sale or
     other disposition of any portion of any Investment in an Unrestricted
     Subsidiary not to exceed the amount of Investments previously made by the
     Company or any Restricted Subsidiary in such Unrestricted Subsidiary, which
     amount was included in the calculation of the amount of Restricted Payments
     under this clause (c) and not otherwise included in the calculation of
     Consolidated Net Income, plus (v) $5.0 million.
 
     The foregoing provisions will not prohibit (i) the payment of any dividend
within 60 days after the date of declaration thereof, if at said date of
declaration such payment would have complied with the provisions of the
Indenture; (ii) the making of any Restricted Investment in exchange for, or out
of the proceeds of, the substantially concurrent sale (other than to a
Subsidiary of the Company) of, or from substantially concurrent additional
capital contributions in respect of, Equity Interests of the Company (other than
Disqualified Stock); provided that the amount of any such cash proceeds that are
utilized for any such Restricted Investment shall be excluded from clause
(c)(ii) of the preceding paragraph; (iii) the redemption, repurchase, retirement
or other acquisition of any Equity Interests of the Company in exchange for, or
out of the proceeds of, the substantially concurrent sale (other than to a
Subsidiary of the Company) of, or from substantially concurrent additional
capital contributions (other than from a Subsidiary of the Company) in respect
of, other Equity Interests of the Company (other than any Disqualified Stock);
provided that the amount of any such net cash proceeds that are utilized for any
such redemption, repurchase, retirement or other acquisition shall be excluded
from clause (c)(ii) of the preceding paragraph; (iv) the defeasance, redemption
or repurchase of subordinated Indebtedness with the net cash proceeds from (X)
an incurrence of Permitted Refinancing Indebtedness or (Y) the substantially
concurrent sale (other than to a Subsidiary of the Company) of, or from
substantially concurrent additional capital contributions (other than from a
Subsidiary of the Company) in respect of, Equity Interests of the Company (other
than Disqualified Stock); provided that the amount of any such net cash proceeds
that are utilized for any such defeasance, redemption
 
                                       73
<PAGE>   75
 
or repurchase shall be excluded from clause (c)(ii) of the preceding paragraph;
(v) any dividend or other distribution made by any Wholly Owned Subsidiary of
the Company to another Wholly Owned Subsidiary of the Company or to the Company;
and (vi) the repurchase, retirement or other acquisition or retirement for value
of common Equity Interests of the Company held by any future, present or former
employee or director of the Company or any of the Company's Restricted
Subsidiaries pursuant to any management equity plan or stock option plan or any
other management or employee benefit plan or agreement in connection with the
termination of such person's employment for any reason (including by reason of
death or disability); provided, however, that the aggregate Restricted Payments
made under this clause (vi) do not exceed in any calendar year $2.5 million
(with unused amounts in any calendar year being carried over to succeeding
calendar years subject to a maximum (without giving effect to the following
proviso) of $7.5 million in any calendar year); provided further that such
amount in any calendar year may be increased by an amount not to exceed (A) the
cash proceeds received by the Company from the sale of Equity Interests of the
Company to members of management or directors of the Company and its Restricted
Subsidiaries that occurs after the Issue Date (to the extent the cash proceeds
from the sale of such Equity Interests have not otherwise been applied to the
payment of Restricted Payments by virtue of the preceding paragraph (c)), plus
(B) the cash proceeds of key man life insurance policies received by the Company
and its Restricted Subsidiaries after the Issue Date, less (C) the amount of any
Restricted Payments made pursuant to clauses (A) and (B) of this subparagraph
(vi); provided however that in the case of any transaction described in clauses
(ii) through (iv) and clause (vi) no Default or Event of Default will have
occurred and be continuing immediately after such transaction. In determining
the aggregate amount of Restricted Payments made after the date of the
Indenture, 100% of the amounts expended pursuant to the foregoing clauses (i)
and (vi) shall be included in such calculation and none of the amounts expended
pursuant to the foregoing clauses (ii), (iii), (iv) and (v) shall be included in
such calculation.
 
     As of the date hereof and as of the issue date of the Notes, all of the
Company's Subsidiaries were Restricted Subsidiaries. The Board of Directors may
designate any Subsidiary to be an Unrestricted Subsidiary if such designation
would not cause a Default. For purposes of making such determination, all
outstanding Investments by the Company and its Restricted Subsidiaries (except
to the extent repaid in cash) in the Subsidiary so designated will be deemed to
be Restricted Payments at the time of such designation and will reduce the
amount available for Restricted Payments under the first paragraph of this
covenant. Such designation will only be permitted if such Restricted Payment
would be permitted at such time and if such Subsidiary otherwise meets the
definition of an Unrestricted Subsidiary.
 
     The amount of all Restricted Payments (other than cash) shall be the fair
market value (evidenced by a resolution of the Board of Directors set forth in
an Officers' Certificate delivered to the Trustee) on the date of the Restricted
Payment of the asset(s) proposed to be transferred by the Company or the
applicable Restricted Subsidiary, as the case may be, pursuant to the Restricted
Payment. Not later than the date of making any Restricted Payment, the Company
will deliver to the Trustee an Officers' Certificate stating that such
Restricted Payment is permitted and setting forth the basis upon which the
calculation required by this covenant were computed, which calculations may be
based upon the Company's latest available financial statements.
 
  Incurrence of Indebtedness and Issuance of Preferred Stock
 
     The Indenture provides that the Company will not, and will not permit any
of its Restricted Subsidiaries to, directly or indirectly, create, incur, issue,
assume, guarantee or otherwise become directly or indirectly liable,
contingently or otherwise, with respect to (collectively, "incur") any
Indebtedness (including Acquired Indebtedness) and that the Company will not
issue any shares of Disqualified Stock and will not permit any of its Restricted
Subsidiaries to issue any shares of preferred stock; provided, however, that the
Company may incur Indebtedness (including Acquired Indebtedness) or issue shares
of Disqualified Stock if: (i) the Fixed Charge Coverage Ratio for the Company's
most recently ended four full fiscal quarters for which internal financial
statements are available immediately preceding the date on which such additional
Indebtedness is incurred or such Disqualified Stock is issued would have been at
least 2.5 to 1.0, determined on a pro forma basis (including a pro forma
application of the net proceeds therefrom), as if the additional Indebtedness
had
 
                                       74
<PAGE>   76
 
been incurred, or the Disqualified Stock had been issued, as the case may be, at
the beginning of such four-quarter period; and (ii) no Default or Event of
Default will have occurred and be continuing or would occur as a consequence
thereof.
 
     The foregoing provisions will not apply to:
 
          (i) the incurrence by the Company of Indebtedness under the Credit
     Agreement, so long as the aggregate principal amount of all Indebtedness
     outstanding under the Credit Agreement does not, at any one time, exceed
     the greater of (i) $150 million (less any amounts outstanding under the
     Credit Agreement on the Issue Date after giving effect to the repayment of
     Indebtedness under the Credit Agreement from the proceeds of the Offering)
     (or, if there is any permanent reduction in the aggregate principal amount
     permitted to be borrowed under the Credit Agreement, such lesser aggregate
     principal amount) and (ii) 30% of Adjusted Consolidated Net Tangible Assets
     determined immediately after the incurrence of such Indebtedness (including
     the application of the proceeds therefrom);
 
          (ii) the incurrence by the Company of Indebtedness represented by the
     Notes or by the Restricted Subsidiaries of Subsidiary Guarantees;
 
          (iii) the guarantee by any Subsidiary Guarantor of any Indebtedness
     that is permitted by the Indenture to be incurred by the Company at the
     time such Indebtedness was incurred;
 
          (iv) the incurrence by the Company or any Restricted Subsidiary of
     Permitted Refinancing Indebtedness in exchange for, or the net proceeds of
     which are used to extend, refinance, renew, replace, defease or refund,
     Indebtedness of such entity that was permitted by the Indenture to be
     incurred (including Indebtedness previously incurred pursuant to this
     clause (iv), but excluding Indebtedness under clauses (i), (iii), (v),
     (vi), and (ix));
 
          (v) the incurrence by the Company or any Restricted Subsidiary of
     intercompany Indebtedness between or among the Company and any of its
     Restricted Subsidiaries or between or among any Restricted Subsidiary;
     provided, however, that (i) any subsequent issuance or transfer of Equity
     Interests that results in any such Indebtedness being held by a Person
     other than a Restricted Subsidiary and (ii) any sale or other transfer of
     any such Indebtedness to a Person that is not either the Company or a
     Restricted Subsidiary will be deemed, in each case, to constitute an
     incurrence of such Indebtedness by the Company or such Restricted
     Subsidiary, as the case may be; provided, further, that if the Company is
     the obligor on such Indebtedness, such Indebtedness is expressly
     subordinate to the payment in full of all Obligations with respect to the
     Notes;
 
          (vi) the incurrence, assumption or creation of Hedging Obligations of
     the Company or a Restricted Subsidiary pursuant to interest rate protection
     obligations, but only to the extent that the stated aggregate notional
     amounts of such obligations do not exceed 105% of the aggregate principal
     amount of the Indebtedness covered by such interest rate protection
     obligations; the incurrence, assumption or creation of Hedging Obligations
     under currency exchange contracts entered into in the ordinary course of
     business for the purpose of limiting risks that arise in the ordinary
     course of business of the Company and its Restricted Subsidiaries; and the
     incurrence, assumption or creation of hedging arrangements that the Company
     or a Restricted Subsidiary enters into in the ordinary course of business
     in the Oil and Gas Business for the purpose of protecting its production
     against fluctuations in oil or natural gas prices;
 
          (vii) Indebtedness or Disqualified Stock of Persons that are acquired
     by the Company or any of its Restricted Subsidiaries or merged into a
     Restricted Subsidiary in accordance with the terms of the Indenture;
     provided that such Indebtedness or Disqualified Stock is not incurred in
     contemplation of such acquisition or merger; and provided further that
     after giving effect to such acquisition, the Company would be permitted to
     incur at least $1.00 of additional Indebtedness pursuant to the Fixed
     Charge Coverage Ratio test set forth in the first paragraph of this
     covenant;
 
          (viii) all Indebtedness of the Company and its Restricted Subsidiaries
     in existence on the date of the Indenture; and
 
                                       75
<PAGE>   77
 
          (ix) the incurrence by the Company and its Restricted Subsidiaries of
     Indebtedness in an aggregate principal amount of up to $40 million (which
     shall be in addition to amounts which may be incurred pursuant to clauses
     (i) through (viii) above).
 
     In the event that Indebtedness falls within more than one category of
permitted Indebtedness under the Indenture, the Company will determine the
applicable category and such Indebtedness will only be counted once. If
Indebtedness is issued at less than the principal amount thereof, the amount of
such Indebtedness for purposes of the above limitations shall equal the amount
of the liability as determined in accordance with GAAP.
 
     The Indenture provides that the Company will not permit any Unrestricted
Subsidiary to incur any Indebtedness other than Non-Recourse Debt; provided,
however, if any such Indebtedness ceases to be Non-Recourse Debt, such event
shall be deemed to constitute an incurrence of Indebtedness by the Company or a
Restricted Subsidiary.
 
  No Layering
 
     The Indenture provides that (i) the Company will not incur, create, issue,
assume, guarantee or otherwise become liable for any Indebtedness that is
subordinate or junior in right of payment to any Senior Debt and senior in any
respect in right of payment to the Notes and (ii) the Subsidiary Guarantors, if
any, will not directly or indirectly incur, create, issue, assume, guarantee or
otherwise become liable for any Indebtedness that is subordinate or junior in
right of payment to Senior Debt and senior in any respect in right of payment to
the Subsidiary Guarantees, if any; provided, however, that the foregoing
limitations will not apply to distinctions between categories of Indebtedness
that exist by reason of any Liens arising or created in accordance with the
provisions of the Indenture in respect of some but not all such Indebtedness.
 
  Liens
 
     The Indenture provides that the Company will not, and will not permit any
of its Restricted Subsidiaries to, create, incur, assume or otherwise cause or
suffer to exist or become effective any Lien securing Indebtedness of any kind
(other than Permitted Liens) upon any of its property or assets, now owned or
hereafter acquired, unless all payments under the Notes are secured by such Lien
prior to, or (if such Indebtedness is pari passu with the Notes) on an equal and
ratable basis with, the Indebtedness so secured for so long as such Indebtedness
is secured by such Lien.
 
  Dividend and Other Payment Restrictions Affecting Restricted Subsidiaries
 
     The Indenture provides that the Company will not, and will not permit any
of its Restricted Subsidiaries to, directly or indirectly, create or otherwise
cause or suffer to exist or become effective any encumbrance or restriction on
the ability of any Restricted Subsidiary to (i) (a) pay dividends or make any
other distributions to the Company or any of its Restricted Subsidiaries (1) on
its Capital Stock or (2) with respect to any other interest or participation in,
or measured by, its profits, or (b) pay any indebtedness owed to the Company or
any of its Restricted Subsidiaries, (ii) make loans or advances to the Company
or any of its Restricted Subsidiaries or (iii) transfer any of its properties or
assets to the Company or any of its Restricted Subsidiaries, except for such
encumbrances or restrictions existing under or by reason of (a) Existing
Indebtedness as in effect on the date of the Indenture, (b) the Credit Agreement
as in effect as of the date of the Indenture, and any amendments, modifications,
restatements, renewals, increases, supplements, refundings, replacements or
refinancings thereof, provided that such amendments, modifications,
restatements, renewals, increases, supplements, refundings, replacements or
refinancings are no more restrictive with respect to such dividend and other
payment restrictions than those contained in the Credit Agreement as in effect
on the date of the Indenture, (c) the Indenture and the Notes, (d) any
instrument governing Acquired Indebtedness or Capital Stock of a Person acquired
by the Company or any of its Restricted Subsidiaries as in effect at the time of
such acquisition (except to the extent such Acquired Indebtedness was incurred
in connection with or in contemplation of such acquisition), which encumbrance
or restriction is not applicable to any Person, or the properties or assets of
any Person, other than the Person, or the property or assets of the
                                       76
<PAGE>   78
 
Person, so acquired, provided that the Consolidated Cashflow of such Person is
not taken into account in determining whether such acquisition was permitted by
the terms of the Indenture, (e) purchase money obligations for property acquired
in the ordinary course of business that impose restrictions of the nature
described in clause (iii) above on the property so acquired, (f) by reason of
customary non-assignment provisions in leases and licenses entered into in the
ordinary course of business and consistent with past practices, (g) agreements
relating to the financing of the acquisition of real or tangible personal
property acquired after the date of the Indenture, provided, that such
encumbrance or restriction relates only to the property which is acquired and in
the case of any encumbrance or restriction that constitutes a Lien, such Lien
constitutes a Purchase Money Lien, (h) applicable law or (i) customary
restrictions contained in asset sale agreements limiting the transfer of such
assets pending the closing of such sale.
 
  Transactions with Affiliates
 
     The Indenture provides that the Company will not, and will not permit any
of its Restricted Subsidiaries to, sell, lease, transfer or otherwise dispose of
any of its properties or assets to, or purchase any property or assets from, or
enter into or make any contract, agreement, understanding, loan, advance or
guarantee with, or for the benefit of, any Affiliate (each of the foregoing, an
"Affiliate Transaction"), unless (i) such Affiliate Transaction is in the
ordinary course of business, (ii) the terms of such Affiliate Transaction are
fair and reasonable to the Company or such Restricted Subsidiary, as the case
may be, and are at least as favorable as the terms which could be obtained by
the Company or such Restricted Subsidiary, as the case may be, in a comparable
transaction made on an arm's-length basis between unaffiliated parties and (iii)
the Company delivers to the Trustee (a) with respect to any Affiliate
Transaction entered into after the date of the Indenture involving aggregate
consideration in excess of $2.5 million, a resolution of the Board of Directors
set forth in an Officers' Certificate certifying that such Affiliate Transaction
complies with clauses (i) and (ii) above and that such Affiliate Transaction has
been approved by a majority of the disinterested members of the Board of
Directors and (b) with respect to any Affiliate Transaction involving aggregate
consideration in excess of $10.0 million, an opinion as to the fairness to the
Company or such Restricted Subsidiary of such Affiliate Transaction from a
financial point of view issued by an investment banking firm of national
standing; provided that the following will not be deemed to be Affiliate
Transactions: (a) reasonable fees and compensation paid to, and indemnity
provided on behalf of, officers and directors of the Company or any Restricted
Subsidiary as determined in good faith by the appropriate Board of Directors or
senior management; (b) transactions with customers, clients, suppliers, joint
venture partners or purchasers or sellers of goods or services, in each case in
the ordinary course of business (including, without limitation, pursuant to
joint venture agreements) and otherwise in compliance with the terms of the
Indenture and which comply with the terms of clause (ii) above; (c) any
employment agreement entered into by the Company or any of its Restricted
Subsidiaries in the ordinary course of business and consistent with the past
practice of the Company or such Restricted Subsidiary (including, without
limitation, any such employment agreements entered into prior to the date of the
Indenture); (d) transactions between or among the Company and/or its Restricted
Subsidiaries; (e) Restricted Payments and Permitted Investments that are
permitted by the provisions of the Indenture described above under the caption
"-- Restricted Payments" and the definition of Permitted Investment; and (f) any
contracts, agreements or understandings existing as of the date of the Indenture
and any amendment thereto or any transaction contemplated thereby (including
pursuant to any amendment thereto or any replacement agreement thereof so long
as any such amendment or replacement agreement is not more disadvantageous to
the holders of the Notes in any material respect than the original agreement as
in effect on the date of the Indenture).
 
  Limitation as to Unrestricted Subsidiaries
 
     The Indenture provides that the Company will not permit any Unrestricted
Subsidiary to create, assume, incur, guarantee or otherwise become liable in
respect of any Indebtedness except Non-Recourse Debt. The Company and its
Restricted Subsidiaries will not designate, create or purchase any Unrestricted
Subsidiary, unless the Board of Directors of the Company shall have made a
determination (as set forth in the resolution approving such designation,
creation or purchase) that the designation, creation and operation of the
Unrestricted Subsidiary is not reasonably expected to materially and adversely
affect the financial condition,
                                       77
<PAGE>   79
 
business, or operations of the Company and its Restricted Subsidiaries taken
together as a whole (which resolution shall be conclusive evidence of compliance
with this provision).
 
  Limitation on Guarantees of Indebtedness by Restricted Subsidiaries
 
     (a) The Indenture provides that the Company will not permit any Restricted
Subsidiary to guarantee the payment of any Indebtedness of the Company unless
(i) such Restricted Subsidiary simultaneously executes and delivers a
supplemental indenture to the Indenture providing for a Subsidiary Guarantee of
such Restricted Subsidiary except that with respect to a guarantee of
Indebtedness of the Company (A) if the Notes are subordinated in right of
payment to such Indebtedness, the Subsidiary Guarantee under the supplemental
indenture shall be subordinated to such Restricted Subsidiary's guarantee with
respect to such Indebtedness substantially to the same extent as the Notes are
subordinated to such Indebtedness under the Indenture and (B) if such
Indebtedness is by its express terms subordinated in right of payment to the
Notes, any such guarantee of such Restricted Subsidiary with respect to such
Indebtedness shall be subordinated in right of payment to such Restricted
Subsidiary's Subsidiary Guarantee with respect to the Notes substantially to the
same extent as such Indebtedness is subordinated to the Notes; (ii) such
Restricted Subsidiary waives and will not in any manner whatsoever claim or take
the benefit or advantage of, any rights of reimbursement, indemnity or
subrogation or any other rights against the Company or any other Restricted
Subsidiary as a result of any payment by such Restricted Subsidiary under its
Subsidiary Guarantee of the Notes; and (iii) such Restricted Subsidiary shall
deliver to the Trustee an opinion of counsel to the effect that (A) such
Subsidiary Guarantee has been duly executed and authorized and (B) such
Subsidiary Guarantee constitutes a valid, binding and enforceable obligation of
such Restricted Subsidiary, except insofar as enforcement thereof may be limited
by bankruptcy, insolvency or similar laws (including, without limitation, all
laws relating to fraudulent transfers) and except insofar as enforcement thereof
is subject to general principles of equity; provided that this paragraph (a)
shall not be applicable to any guarantee of any Restricted Subsidiary (x) that
(A) existed at the time such Person became a Restricted Subsidiary of the
Company and (B) was not incurred in connection with, or in contemplation of,
such Person becoming a Restricted Subsidiary of the Company or (y) that
guarantees the payment of Obligations of the Company under the Credit Agreement
or any other Senior Debt of the Company and any refunding, refinancing or
replacement thereof, in whole or in part, provided that such refunding,
refinancing or replacement thereof constitutes Senior Debt of the Company.
 
     (b) Notwithstanding the foregoing and the other provisions of the
Indenture, any Subsidiary Guarantee shall provide by its terms that it shall be
automatically and unconditionally released and discharged upon (i) any sale,
exchange or transfer, to any Person not an Affiliate of the Company, of all of
the Company's Capital Stock in, or all or substantially all the assets of, such
Restricted Subsidiary whether by way of merger, consolidation or otherwise
(which sale, exchange or transfer is not prohibited by the Indenture), provided
that the Net Proceeds of such sale or other disposition are applied in
accordance with the covenant described under the caption "Repurchase at the
Option of Holders -- Asset Sales," or (ii) the release or discharge of the
guarantee which resulted in the creation of such Subsidiary Guarantee, except a
discharge or release by or as a result of payment under such guarantee.
 
  Line of Business
 
     The Company will not, and will not permit any Subsidiary to, engage in any
line of business other than the Oil and Gas Business, except to the extent as
would not be material to the Company and its Subsidiaries taken as a whole.
 
  Reports
 
     The Indenture provides that, whether or not required by the rules and
regulations of the Commission, so long as any Notes are outstanding, the Company
will furnish to the Holders of Notes, within 15 days after it is or would have
been required to file such with the Commission, (i) all quarterly and annual
financial information that would be required to be contained in a filing with
the Commission on Forms 10-K and 10-Q if the Company was required to file such
Forms, including a "Management's Discussion and Analysis of
                                       78
<PAGE>   80
 
Financial Condition and Results of Operations" and, with respect to the annual
information only, reports thereon by the certified independent accountants of
the Company and (ii) all current reports that would be required to be filed with
the Commission on Form 8-K if the Company was required to file such reports. In
addition, whether or not required by the rules and regulations of the
Commission, the Company will file copies of all such information and reports
with the Commission for public availability (unless the Commission will not
accept such a filing) and make such information available to securities analysts
and prospective investors upon request. In addition, the Company has agreed
that, until the effectiveness of the registration statement relating to the
Exchange Offer pursuant to the Registration Rights Agreement, it will furnish to
the Holders and prospective investors, upon their request, the information
required to be delivered pursuant to Rule 144A(d)(4) under the Securities Act.
 
  Merger, Consolidation, or Sale of Assets
 
     The Indenture provides that the Company shall not, in a single transaction
or series of related transactions, consolidate or merge with or into (whether or
not the Company is the surviving corporation), or directly and/or indirectly
through its Restricted Subsidiaries sell, assign, transfer, lease, convey or
otherwise dispose of all or substantially all of its properties or assets
determined on a consolidated basis for the Company and its Restricted
Subsidiaries taken as a whole in one or more related transactions, to another
Person unless (i) the Company is the surviving corporation or the Person formed
by or surviving any such consolidation or merger (if other than the Company) or
to which such sale, assignment, transfer, lease, conveyance or other disposition
will have been made, is a corporation organized or existing under the laws of
one of the states of the United States or the District of Columbia; (ii) the
Person formed by or surviving any such consolidation or merger (if other than
the Company) or the Person to which such sale, assignment, transfer, lease,
conveyance or other disposition will have been made assumes all the obligations
of the Company, under the Notes and the Indenture pursuant to a supplemental
indenture in a form reasonably satisfactory to the Trustee; (iii) immediately
after such transaction no Default or Event of Default exists; (iv) the Company
or the entity or Person formed by or surviving any such consolidation or merger
(if other than the Company), or to which such sale, assignment, transfer, lease,
conveyance or other disposition will have been made will, at the time of such
transaction and after giving pro forma effect thereto as if such transaction had
occurred at the beginning of the applicable four-quarter period, be permitted to
incur at least $1.00 of additional Indebtedness pursuant to the Fixed Charge
Coverage Ratio test set forth in the first paragraph of the covenant described
above under the caption "-- Incurrence of Indebtedness and Issuance of Preferred
Stock"; and (v) the Company delivers to the Trustee an Officers' Certificate and
an Opinion of Counsel addressed to the Trustee with respect to the foregoing
matters. Each Subsidiary Guarantor, if any, unless it is the other party to the
transactions described above, shall have confirmed by supplemental indenture
that its Subsidiary Guarantee shall apply to such Person's obligations under the
Indenture and the Notes. Subject to the provisions of the succeeding sentence
relating to sales of Subsidiary Guarantors, the Indenture provides that no
Subsidiary Guarantor may consolidate with, or merge with or into (whether or not
such Subsidiary Guarantor is the surviving Person), another Person other than
the Company or another Subsidiary Guarantor whether or not affiliated with such
Subsidiary Guarantor, unless (i) subject to the provisions of the following
sentence, the Person formed by or surviving any such consolidation or merger (if
other than such Subsidiary Guarantor) assumes all the obligations of such
Subsidiary Guarantor pursuant to a supplemental indenture in form and substance
reasonably satisfactory to the Trustee in respect of the Notes, the Indenture
and the Guarantees; (ii) immediately after giving effect to such transaction, no
Default or Event of Default exists; and (iii) the Company delivers to the
Trustee an Officers' Certificate and an Opinion of Counsel addressed to the
Trustee with respect to the foregoing matters. The Indenture provides that in
the event of a sale or other disposition of all or substantially all of the
assets of a Subsidiary Guarantor to a third party, by way of merger,
consolidation or otherwise, or a sale or other disposition of all of the Capital
Stock of a Subsidiary Guarantor, then such Subsidiary Guarantor (in the event of
a sale or other disposition, by way of such a merger, consolidation or
otherwise, of all of the Capital Stock of such Subsidiary Guarantor) or the
Person acquiring the property (in the event of a sale or other disposition of
all or substantially all of the assets of such Subsidiary Guarantor) will be
released from and relieved of any obligations under its Subsidiary Guarantee;
provided that the Net Proceeds of such sale or other disposition are applied in
accordance with the covenant described under the
 
                                       79
<PAGE>   81
 
caption "Repurchase at the Option of Holders -- Asset Sales." Further,
notwithstanding the foregoing, the merger of the Company with an Affiliate
incorporated solely for the purpose of reincorporating the Company in another
jurisdiction shall be permitted.
 
EFFECTIVENESS OF COVENANTS
 
     The covenants described under "-- Restricted Payments," "-- Incurrence of
Indebtedness and Issue of Preferred Stock" "-- No Layering," "-- Liens,"
"-- Dividends and Other Payment Restrictions Affecting Restricted Subsidiaries,"
"-- Transactions with Affiliates" and "-- Limitation as to Unrestricted
Subsidiaries," will no longer be in effect upon the Company reaching Investment
Grade Status.
 
EVENTS OF DEFAULT AND REMEDIES
 
     The Indenture provides that each of the following constitutes an Event of
Default: (i) default for 30 days in the payment when due of interest on, or
Liquidated Damages with respect to, the Notes; (ii) default in payment when due
of the principal of or premium, if any, on the Notes; (iii) failure by the
Company to comply with the provisions described under the captions
"-- Repurchase at the Option of Holders -- Change of Control," "-- Repurchase at
the Option of Holders -- Asset Sales," "-- Restricted Payments," or "-- Merger,
Consolidation or Sale of Assets"; (iv) failure by the Company or a Subsidiary
Guarantor, if any, for 60 days after notice from the Trustee or the Holders of
at least 25% in principal amount of the then outstanding Notes to comply with
any of its other agreements in the Indenture or the Notes; (v) except as
permitted by the Indenture, any Subsidiary Guarantee shall be held in any
judicial proceeding to be unenforceable or invalid or shall cease for any reason
to be in full force and effect or a Subsidiary, or any Person acting on behalf
of such Subsidiary, shall deny or disaffirm its obligations under its Subsidiary
Guarantee; (vi) default under any mortgage, indenture or instrument under which
there may be issued or by which there may be secured or evidenced any
Indebtedness for money borrowed by the Company or any of its Restricted
Subsidiaries (or the payment of which is guaranteed by the Company or any of its
Restricted Subsidiaries), other than Indebtedness owed to the Company or a
Wholly Owned Subsidiary, whether such Indebtedness or guarantee now exists, or
is created after the date of the Indenture, which default (a) is caused by a
failure to pay principal of or premium, if any, or interest on such Indebtedness
prior to the expiration of the grace period provided in such Indebtedness on the
date of such default unless being contested in good faith by appropriate
proceedings (a "Payment Default") or (b) results in the acceleration of such
Indebtedness prior to its express maturity and, in each case, the principal
amount of any such Indebtedness, together with the principal amount of any other
such Indebtedness under which there has been a Payment Default or the maturity
of which has been so accelerated, aggregates $10.0 million or more; (vii)
failure by the Company or any of its Restricted Subsidiaries to pay final
judgments aggregating in excess of $10.0 million, which judgments are not paid,
discharged or stayed for a period of 60 days; and (viii) certain events of
bankruptcy or insolvency with respect to the Company or any of its Significant
Subsidiaries or group of Restricted Subsidiaries that, together taken (as of the
latest audited consolidated financial statements for the Company and its
Subsidiaries), would constitute a Significant Subsidiary.
 
     If any Event of Default occurs and is continuing, the Trustee or the
Holders of at least 25% in principal amount of the then outstanding Notes may
declare all the Notes to be due and payable immediately. Notwithstanding the
foregoing, in the case of an Event of Default arising from certain events of
bankruptcy or insolvency with respect to the Company, any Significant Subsidiary
or any group of Restricted Subsidiaries that, taken together (as of the latest
audited consolidated financial statements for the Company and its Subsidiaries),
would constitute a Significant Subsidiary, all outstanding Notes will become due
and payable without further action or notice. Holders of the Notes may not
enforce the Indenture or the Notes except as provided in the Indenture. Subject
to certain limitations, Holders of a majority in principal amount of the then
outstanding Notes may direct the Trustee in its exercise of any trust or power.
The Trustee may withhold from Holders of the Notes notice of any continuing
Default or Event of Default (except a Default or Event of Default relating to
the payment of principal or interest) if it determines that withholding notice
is in their interest.
 
                                       80
<PAGE>   82
 
     The Holders of a majority in aggregate principal amount of the Notes then
outstanding by notice to the Trustee may on behalf of the Holders of all of the
Notes waive any existing Default or Event of Default and its consequences under
the Indenture except a continuing Default or Event of Default in the payment of
interest on, or the principal of, premium and Liquidated Damages, if any, on the
Notes.
 
     The Company is required to deliver to the Trustee annually a statement
regarding compliance with the Indenture, and the Company is required upon
becoming aware of any Default or Event of Default, to deliver to the Trustee a
statement specifying such Default or Event of Default.
 
NO PERSONAL LIABILITY OF DIRECTORS, OFFICERS, EMPLOYEES AND STOCKHOLDERS
 
     No director, officer, employee, incorporator or stockholder of the Company,
as such, will have any liability for any obligations of the Company under the
Notes, the Indenture or for any claim based on, in respect of, or by reason of,
such obligations or their creation. Each Holder of Notes by accepting a Note
waives and releases all such liability. The waiver and release are part of the
consideration for issuance of the Notes. Such waiver may not be effective to
waive liabilities under the federal securities laws and it is the view of the
Commission that such a waiver is against public policy.
 
LEGAL DEFEASANCE AND COVENANT DEFEASANCE
 
     The Company may, at its option and at any time, elect to have all of its
and the Subsidiary Guarantors' obligations, if any, discharged with respect to
the outstanding Notes ("Legal Defeasance") except for (i) the rights of Holders
of outstanding Notes to receive payments in respect of the principal of,
premium, if any, and interest and Liquidated Damages, if any, on such Notes when
such payments are due from the trust referred to below, (ii) the Company's
obligations with respect to the Notes concerning issuing temporary Notes,
registration of Notes, mutilated, destroyed, lost or stolen Notes and the
maintenance of an office or agency for payment and money for security payments
held in trust, (iii) the rights, powers, trusts, duties and immunities of the
Trustee, and the Company's obligations in connection therewith and (iv) the
Legal Defeasance provisions of the Indenture. In addition, the Company may, at
its option and at any time, elect to have the obligations of the Company
released with respect to certain covenants that are described in the Indenture
("Covenant Defeasance") and thereafter any omission to comply with such
obligations will not constitute a Default or Event of Default with respect to
the Notes. In the event Covenant Defeasance occurs, certain events (not
including nonpayment, bankruptcy, receivership, rehabilitation and insolvency
events) described under "Events of Default" will no longer constitute an Event
of Default with respect to the Notes.
 
     In order to exercise either Legal Defeasance or Covenant Defeasance, (i)
the Company must irrevocably deposit with the Trustee, in trust, for the benefit
of the Holders of the Notes, cash in U.S. dollars, non-callable Government
Securities, or a combination thereof, in such amounts as will be sufficient, in
the opinion of a nationally recognized firm of independent public accountants,
to pay the principal of, premium, if any, and interest and Liquidated Damages,
if any, on the outstanding Notes on the stated maturity or on the applicable
redemption date, as the case may be, and the Company must specify whether the
Notes are being defeased to maturity or to a particular redemption date; (ii) in
the case of Legal Defeasance, the Company will have delivered to the Trustee an
opinion of counsel in the United States reasonably acceptable to the Trustee
confirming that (A) the Company has received from, or there has been published
by, the Internal Revenue Service a ruling or (B) since the date of the
Indenture, there has been a change in the applicable U.S. federal income tax
law, in either case to the effect that, and based thereon such opinion of
counsel will confirm that, the Holders of the outstanding Notes will not
recognize income, gain or loss for federal income tax purposes as a result of
such Legal Defeasance and will be subject to federal income tax on the same
amounts, in the same manner and at the same times as would have been the case if
such Legal Defeasance had not occurred; (iii) in the case of Covenant
Defeasance, the Company will have delivered to the Trustee an opinion of counsel
in the United States reasonably acceptable to the Trustee confirming that the
Holders of the outstanding Notes will not recognize income, gain or loss for
U.S. federal income tax purposes as a result of such Covenant Defeasance and
will be subject to U.S. federal income tax on the same amounts, in the same
manner and at the same times as would have been the case if such Covenant
Defeasance had not occurred; (iv) no Default or Event of Default will have
occurred and be continuing on the date of such deposit (other than a Default or
                                       81
<PAGE>   83
 
Event of Default resulting from the borrowing of funds to be applied to such
deposit) or insofar as Events of Default from bankruptcy or insolvency events
are concerned, at any time in the period ending on the 91st day after the date
of deposit; (v) such Legal Defeasance or Covenant Defeasance will not result in
a breach or violation of, or constitute a default under any material agreement
or instrument (other than the Indenture) to which the Company or any of its
Subsidiaries is a party or by which the Company or any of its Subsidiaries is
bound; (vi) the Company must have delivered to the Trustee an opinion of counsel
to the effect that on the 91st day following the deposit, the trust funds will
not be subject to the effect of any applicable bankruptcy, insolvency,
reorganization or similar laws affecting creditors' rights generally; (vii) the
Company must deliver to the Trustee an Officers' Certificate stating that the
deposit was not made by the Company with the intent of preferring the Holders of
the Notes over the other creditors of the Company with the intent of defeating,
hindering, delaying or defrauding creditors of the Company or others; and (viii)
the Company must deliver to the Trustee an Officers' Certificate and an opinion
of counsel, each stating that all conditions precedent provided for relating to
the Legal Defeasance or the Covenant Defeasance have been complied with.
 
TRANSFER AND EXCHANGE
 
     A Holder may transfer or exchange Notes in accordance with the Indenture.
The Registrar and the Trustee may require a Holder, among other things, to
furnish appropriate endorsements and transfer documents and the Company may
require a Holder to pay any taxes and fees required by law or permitted by the
Indenture. The Company is not required to transfer or exchange any Note selected
for redemption. Also, the Company is not required to transfer or exchange any
Note for a period of 15 days before a selection of Notes to be redeemed.
 
     The registered Holder of a Note will be treated as the owner of it for all
purposes.
 
AMENDMENT, SUPPLEMENT AND WAIVER
 
     Except as provided in the next two succeeding paragraphs, the Indenture,
the Notes or the Subsidiary Guarantees, if any, may be amended or supplemented
with the consent of the Holders of at least a majority in principal amount of
the Notes then outstanding (including consents obtained in connection with a
tender offer or exchange offer for Notes), and, subject to certain exceptions,
any existing default or compliance with any provision of the Indenture, the
Notes or the Subsidiary Guarantees, if any, may be waived with the consent of
the Holders of a majority in principal amount of the then outstanding Notes
(including consents obtained in connection with a tender offer or exchange offer
for Notes).
 
     Without the consent of each Holder affected, an amendment or waiver may not
(with respect to any Notes held by a non-consenting Holder): (i) reduce the
principal amount of Notes whose Holders must consent to an amendment, supplement
or waiver, (ii) reduce the principal of or change the fixed maturity of any Note
or alter the provisions with respect to the redemption of the Notes (other than
provisions relating to the covenants described above under the caption
"-- Repurchase at the Option of Holders"), (iii) reduce the rate of or change
the time for payment of interest or Liquidated Damages, if any, on any Note,
(iv) waive a Default or Event of Default in the payment of principal of or
premium, if any, or interest or Liquidated Damages, if any, on the Notes (except
a rescission of acceleration of the Notes from a non payment default by the
Holders of at least a majority in aggregate principal amount of the Notes and a
waiver of the payment default that resulted from such acceleration), (v) make
any Note payable in money other than that stated in the Notes, (vi) make any
change in the provisions of the Indenture relating to waivers of past Defaults
or the rights of Holders of Notes to receive payments of principal of or
premium, if any, or interest or Liquidated Damages, if any, on the Notes, (vii)
waive a redemption payment with respect to any Note (other than a payment
required by one of the covenants described above under the caption
"-- Repurchase at the Option of Holders") or (viii) make any change in the
foregoing amendment and waiver provisions. In addition, any amendment to the
provisions of the Indenture (which relate to subordination) will require the
consent of the Holders of at least 66 2/3% in principal amount of Notes then
outstanding if such amendment would adversely affect the rights of Holders of
such Notes. However, no amendment may be made to the subordination provisions of
the Indenture that adversely affects the rights of any holder of Senior Debt
then outstanding
 
                                       82
<PAGE>   84
 
unless the holders of such Senior Debt (or any group or representative thereof
authorized to give a consent) consent to such change.
 
     Notwithstanding the foregoing, without the consent of any Holder of Notes,
the Company and the Trustee may amend or supplement the Indenture, the Notes or
the Subsidiary Guarantees, if any, to cure any ambiguity, defect or
inconsistency, to provide for uncertificated Notes in addition to or in place of
certificated Notes, to provide for the assumption of the Company's or any
Subsidiary Guarantor's obligations to Holders of Notes in the case of a merger
or consolidation, to make any change that would provide any additional rights or
benefits to the Holders of Notes (including additional Subsidiary Guarantees) or
that does not adversely affect the legal rights under the Indenture of any such
Holder, or to comply with requirements of the Commission in order to effect or
maintain the qualification of the Indenture under the Trust Indenture Act or to
provide for the succession of a successor Trustee.
 
CONCERNING THE TRUSTEE
 
     The Indenture contains certain limitations on the rights of the Trustee,
should it become a creditor of the Company, to obtain payment of claims in
certain cases, or to realize on certain property received in respect of any such
claim as security or otherwise. The Trustee will be permitted to engage in other
transactions; however, if it acquires any conflicting interest it must eliminate
such conflict within 90 days or apply to the Commission for permission to
continue or resign.
 
     The Holders of a majority in principal amount of the then outstanding Notes
will have the right to direct the time, method and place of conducting any
proceeding for exercising any remedy available to the Trustee, subject to
certain exceptions. The Indenture provides that in case an Event of Default will
occur (which will not be cured), the Trustee will be required, in the exercise
of its power, to use the degree of care of a prudent man in the conduct of his
own affairs. Subject to such provisions, the Trustee will be under no obligation
to exercise any of its rights or powers under the Indenture at the request of
any Holder of Notes, unless such Holder will have offered to the Trustee
security and indemnity satisfactory to it against any loss, liability or
expense.
 
BOOK-ENTRY; DELIVERY; FORM AND TRANSFER
 
     The Old Notes held by Qualified Institutional Buyers are in the form of one
registered global note without interest coupons (the "U.S. Global Note"). The
U.S. Global Note was deposited on the date of the closing of the sale of the Old
Notes with the Trustee, as custodian for The Depository Trust Company ("DTC"),
in New York, New York, and will continue to be registered in the name of DTC or
its nominee, in each case for credit to the accounts of DTC's Direct and
Indirect Participants (as defined below). The Old Notes sold in offshore
transactions in reliance on Regulation S, if any, are in the form of one
registered, global book-entry note without interest coupons (the "Reg S Global
Note"). The Reg S Global Note was deposited with the Trustee, as custodian for
DTC, in New York, New York, and registered in the name of a nominee of DTC (a
"Nominee") for credit to the accounts of Indirect Participants at the Euroclear
System ("Euroclear") and Cedel Bank, societe anonyme ("CEDEL"). During the
40-day period commencing on the day after the later of the offering date and the
original Issue Date (as defined) of the Notes (the "40-Day Restricted Period"),
beneficial interests in the Reg S Global Note may be held only through Euroclear
or CEDEL. The U.S. Global Note and the Reg S Global Note are referred to herein
together as the "Global Old Notes."
 
     The Exchange Notes also will be issued in the form of one or more Global
Notes (the "Global Exchange Notes" and, together with the Global Old Notes, the
"Global Notes"). The Global Exchange Notes will be deposited on the original
date of issuance of the Exchange Notes with, or on behalf of, DTC and registered
in the name of Cede & Co., as nominee.
 
     The Global Notes may be transferred, in whole and not in part, only to
another nominee of DTC or to a successor of DTC or its nominee in certain
limited circumstances. Beneficial interests in the Global Notes may be exchanged
for Notes in certificated form in certain limited circumstances. See
"-- Transfer of Interests in Global Notes for Certificated Notes."
                                       83
<PAGE>   85
 
     The Notes may be presented for registration of transfer and exchange at the
offices of the Registrar.
 
  Depositary Procedures
 
     DTC has advised the Company that DTC is a limited-purpose trust company
created to hold securities for its participating organizations (collectively,
the "Direct Participants") and to facilitate the clearance and settlement of
transactions in those securities between Direct Participants through electronic
book-entry changes in accounts of Direct Participants. The Direct Participants
include securities brokers and dealers (including the Initial Purchasers),
banks, trust companies, clearing corporations and certain other organizations,
including Euroclear and Cedel. Access to DTC's system is also available to other
entities that clear through or maintain a direct or indirect, custodial
relationship with a Direct Participant (collectively, the "Indirect
Participants"). DTC may hold securities beneficially owned by other persons only
through the Direct Participants or Indirect Participants and such other persons'
ownership interest and transfer of ownership interest will be recorded only on
the records of the Direct Participant and/or Indirect Participant, and not on
the records maintained by DTC.
 
     DTC has also advised the Company that, pursuant to DTC's procedures, (i)
upon deposit of the Global Notes, DTC will credit the accounts of the Direct
Participants designated by the Initial Purchasers with portions of the principal
amount of the Global Notes allocated by the Initial Purchasers to such Direct
Participants, and (ii) DTC will maintain records of the ownership interests of
such Direct Participants in the Global Notes and the transfer of ownership
interests by and between Direct Participants. DTC will not maintain records of
the ownership interests of, or the transfer of ownership interests by and
between, Indirect Participants or other owners of beneficial interests in the
Global Notes. Direct Participants and Indirect Participants must maintain their
own records of the ownership interests of, and the transfer of ownership
interests by and between, Indirect Participants and other owners of beneficial
interests in the Global Notes.
 
     Investors in the U.S. Global Note may hold their interests therein directly
through DTC if they are Direct Participants in DTC or indirectly through
organizations that are Direct Participants in DTC. Investors in the Reg S Global
Note may hold their interests therein directly through Euroclear or CEDEL or
indirectly through organizations that are participants in Euroclear or CEDEL.
After the expiration of the 40-Day Restricted Period (but not earlier),
investors may also hold interests in the Reg S Global Notes through
organizations other than Euroclear and CEDEL that are Direct Participants in the
DTC system. Morgan Guaranty Trust Company of New York, Brussels office is the
operator and depository of Euroclear and Citibank, N.A. is the operator and
depository of CEDEL (each a "Nominee" of Euroclear and CEDEL, respectively).
Therefore, they will each be recorded on DTC's records as the holders of all
ownership interests held by them on behalf of Euroclear and CEDEL, respectively.
Euroclear and CEDEL will maintain on their records the ownership interests, and
transfers of ownership interests by and between, their own customers' securities
accounts. DTC will not maintain records of the ownership interests of, or the
transfer of ownership interests by and between, customers of Euroclear or CEDEL.
All ownership interests in any Global Notes, including those of customers'
securities accounts held through Euroclear or CEDEL, may be subject to the
procedures and requirements of DTC.
 
     The laws of some states require that certain persons take physical delivery
in definitive, certificated form, of securities that they own. This may limit or
curtail the ability to transfer beneficial interests in a Global Note to such
persons. Because DTC can act only on behalf of Direct Participants, which in
turn act on behalf of Indirect Participants and others, the ability of a person
having a beneficial interest in a Global Note to pledge such interest to persons
or entities that are not Direct Participants in DTC, or to otherwise take
actions in respect of such interests, may be affected by the lack of physical
certificates evidencing such interests. For certain other restrictions on the
transferability of the Notes see "-- Transfers of Interests in Global Notes for
Certificated Notes."
 
     EXCEPT AS DESCRIBED IN "-- TRANSFERS OF INTERESTS IN GLOBAL NOTES FOR
CERTIFICATED NOTES," OWNERS OF BENEFICIAL INTERESTS IN THE GLOBAL NOTES WILL NOT
HAVE NOTES REGISTERED IN THEIR NAMES, WILL NOT RECEIVE PHYSICAL DELIVERY OF
NOTES IN CERTIFICATED FORM AND WILL NOT BE CONSIDERED THE REGISTERED OWNERS OR
HOLDERS THEREOF UNDER THE INDENTURE FOR ANY PURPOSE.
 
                                       84
<PAGE>   86
 
     Under the terms of the Indenture, the Company and the Trustee will treat
the persons in whose names the Notes are registered (including Notes represented
by Global Notes) as the owners thereof for the purpose of receiving payments and
for any and all other purposes whatsoever. Payments in respect of the principal,
premium, Liquidated Damages, if any, and interest on Global Notes registered in
the name of DTC or its nominee will be payable by the Trustee to DTC or its
nominee as the registered holder under the Indenture. Consequently, neither the
Company, the Trustee nor any agent of the Company or the Trustee has or will
have any responsibility or liability for (i) any aspect of DTC's records or any
Direct Participant's or Indirect Participant's records relating to or payments
made on account of beneficial ownership interests in the Global Notes or for
maintaining, supervising or reviewing any of DTC's records or any Direct
Participant's or Indirect Participant's records relating to the beneficial
ownership interests in any Global Note or (ii) any other matter relating to the
actions and practices of DTC or any of its Direct Participants or Indirect
Participants.
 
     DTC has advised the Company that its current payment practice (for payments
of principal, interest and the like) with respect to securities such as the
Notes is to credit the accounts of the relevant Direct Participants with such
payment on the payment date in amounts proportionate to such Direct
Participant's respective ownership interests in the Global Notes as shown on
DTC's records. Payments by Direct Participants and Indirect Participants to the
beneficial owners of the Notes will be governed by standing instructions and
customary practices between them and will not be the responsibility of DTC, the
Trustee or the Company. Neither the Company nor the Trustee will be liable for
any delay by DTC or its Direct Participants or Indirect Participants in
identifying the beneficial owners of the Notes, and the Company and the Trustee
may conclusively rely on and will be protected in relying on instructions from
DTC or its nominee as the registered owner of the Notes for all purposes.
 
     The Global Notes will trade in DTC's Same-Day Funds Settlement System and,
therefore, transfers between Direct Participants in DTC will be effected in
accordance with DTC's procedures, and will be settled in immediately available
funds. Transfers between Indirect Participants (other than Indirect Participants
who hold an interest in the Notes through Euroclear or CEDEL) who hold an
interest through a Direct Participant will be effected in accordance with the
procedures of such Direct Participant but generally will settle in immediately
available funds. Transfers between and among Indirect Participants who hold
interests in the Notes through Euroclear and CEDEL will be effected in the
ordinary way in accordance with their respective rules and operating procedures.
 
     Subject to compliance with the transfer restrictions applicable to the
Notes described herein, cross-market transfers between Direct Participants in
DTC, on the one hand, and Indirect Participants who hold interests in the Notes
through Euroclear or CEDEL, on the other hand, will be effected by Euroclear's
or CEDEL's respective Nominee through DTC in accordance with DTC's rules on
behalf of Euroclear or CEDEL; however, delivery of instructions relating to
crossmarket transactions must be made directly to Euroclear or CEDEL, as the
case may be, by the counterparty in accordance with the rules and procedures of
Euroclear or CEDEL and within their established deadlines (Brussels time for
Euroclear and UK time for CEDEL). Indirect Participants who hold interest in the
Notes through Euroclear and CEDEL may not deliver instructions directly to
Euroclear's or CEDEL's Nominee. Euroclear or CEDEL will, if the transaction
meets its settlement requirements, deliver instructions to its respective
Nominee to deliver or receive interests on Euroclear's or CEDEL's behalf in the
relevant Global Note in DTC, and make or receive payment in accordance with
normal procedures for same-day fund settlement applicable to DTC.
 
     Because of time zone differences, the securities accounts of an Indirect
Participant who holds an interest in the Notes through Euroclear or CEDEL
purchasing an interest in a Global Note from a Direct Participant in DTC will be
credited, and any such crediting will be reported to Euroclear or CEDEL during
the European business day immediately following the settlement date of DTC in
New York. Although recorded in DTC's accounting records as of DTC's settlement
date in New York, Euroclear and CEDEL customers will not have access to the cash
amount credited to their accounts as a result of a sale of an interest in a Reg
S Global Note to a DTC Participant until the European business day for Euroclear
or CEDEL immediately following DTC's settlement date.
 
                                       85
<PAGE>   87
 
     DTC has advised the Company that it will take any action permitted to be
taken by a holder of Notes only at the direction of one or more Direct
Participants to whose account interests in the Global Notes are credited and
only in respect of such portion of the aggregate principal amount of the Notes
as to which such Direct Participant or Direct Participants has or have given
direction. However, if there is an Event of Default under the Notes, DTC
reserves the right to exchange Global Notes (without the direction of one or
more of its Direct Participants) for legended Notes in certificated form, and to
distribute such certificated forms of Notes to its Direct Participants. See
"-- Transfers of Interests in Global Notes for Certificated Notes."
 
     Although DTC, Euroclear and CEDEL have agreed to the foregoing procedures
to facilitate transfers of interests in the Reg S Global Note and in the U.S.
Global Note among Direct Participants, Euroclear and CEDEL, they are under no
obligation to perform or to continue to perform such procedures, and such
procedures may be discontinued at any time. None of the Company, the Initial
Purchasers or the Trustee will have any responsibility for the performance by
DTC, Euroclear or CEDEL or their respective Direct and Indirect Participants of
their respective obligations under the rules and procedures governing any of
their operations.
 
     The information in this section concerning DTC, Euroclear and CEDEL and
their book-entry systems has been obtained from sources that the Company
believes to be reliable, but the Company takes no responsibility for the
accuracy thereof.
 
     Transfers of Interests in One Global Note for Interests in Another Global
Note
 
     Prior to the expiration of the 40-Day Restricted Period, an Indirect
Participant who holds an interest in the Reg S Global Note through Euroclear or
CEDEL will be permitted to transfer its interest to a U.S. Person who takes
delivery in the form of an interest in U.S. Global Notes only if such exchange
occurs in connection with a transfer of the Notes pursuant to Rule 144A and the
transferor first delivers to the Trustee a written certificate (in the form
provided in the Indenture) to the effect that the Notes are being transferred to
a person who the transferor reasonably believes is a "qualified institutional
buyer" within the meaning of Rule 144A, purchasing for its own account or the
account of a "qualified institutional buyer" in a transaction meeting the
requirements of Rule 144A and in accordance with all applicable securities laws
of the states of the United States and other jurisdictions.
 
     Beneficial interests in a U.S. Global Note may be transferred to a person
who takes delivery in the form of an interest in the Reg S Global Note, only if
the transferor first delivers to the Trustee a written certificate (in the form
provided in the Indenture) to the effect that such transfer is being made in
accordance with Rule 903 or 904 of Regulation S and if requested by the Company
or the Trustee, the delivery of an opinion of counsel, certification and/or
other information satisfactory to them. If such transfer occurs prior to the
expiration of the 40-Day Restricted Period, the interest transferred will be
held immediately thereafter through Euroclear or CEDEL.
 
     Transfers involving an exchange of a beneficial interest in the Reg S
Global Note for a beneficial interest in the U.S. Global Note or vice versa will
be effected by DTC by means of an instruction originated by the Trustee through
DTC/Deposit Withdraw at Custodian (DWAC) system. Accordingly, in connection with
such transfer, appropriate adjustments will be made to reflect a decrease in the
principal amount of the one Global Note and a corresponding increase in the
principal amount of the other Global Note, as applicable. Any beneficial
interest in the one Global Note that is transferred to a person who takes
delivery in the form of the other Global Note will, upon transfer, cease to be
an interest in such first Global Note and become an interest in such other
Global Note and, accordingly, will thereafter be subject to all transfer
restrictions and other procedures applicable to beneficial interests in such
other Global Note for as long as it remains such an interest.
 
     Transfers of Interests in Global Notes for Certificated Notes
 
     An entire Global Note may be exchanged for definitive Notes in registered,
certificated form without interest coupons ("Certificated Notes") if (i) DTC (x)
notifies the Company that it is unwilling or unable to continue as depositary
for the Global Notes and the Company thereupon fails to appoint a successor
                                       86
<PAGE>   88
 
depositary within 90 days or (y) has ceased to be a clearing agency registered
under the Exchange Act, (ii) the Company, at its option, notifies the Trustee in
writing that it elects to cause the issuance of Certificated Notes or (iii)
there shall have occurred and be continuing a Default or an Event of Default
with respect to the Notes. In any such case, the Company will notify the Trustee
in writing that, upon surrender by the Direct and Indirect Participants of their
interest in such Global Note, Certificated Notes will be issued to each person
that such Direct and Indirect Participants and the DTC identify as being the
beneficial owner of the related Notes.
 
     Beneficial interests in Global Notes held by any Direct or Indirect
Participant may be exchanged for Certificated Notes upon request to DTC, by such
Direct Participant (for itself or on behalf of an Indirect Participant), to the
Trustee in accordance with customary DTC procedures. Certificated Notes
delivered in exchange for any beneficial interest in any Global Note will be
registered in the names, and issued in any approved denominations, requested by
DTC on behalf of such Direct or Indirect Participants (in accordance with DTC's
customary procedures).
 
     In all cases described herein, such Certificated Notes will bear the
restrictive legend referred to in "Notice to Investors," unless the Company
determines otherwise in compliance with applicable law.
 
     Neither the Company nor the Trustee will be liable for any delay by the
holder of any Global Note or DTC in identifying the beneficial owners of Notes,
and the Company and the Trustee may conclusively rely on, and will be protected
in relying on, instructions from the holder of the Global Note or DTC for all
purposes.
 
     Transfers of Certificated Notes for Interests in Global Notes
 
     Certificated Notes may only be transferred if the transferor first delivers
to the Trustee a written certificate (and, in certain circumstances, an opinion
of counsel) confirming that, in connection with such transfer, it has complied
with the restrictions on transfer described under "Notice to Investors."
 
     Same Day Settlement and Payment
 
     The Indenture requires that payments in respect of the Notes represented by
the Global Notes (including principal, premium, if any, interest and Liquidated
Damages, if any) be made by wire transfer of immediately available same day
funds to the accounts specified by the holder of interests in such Global Note.
With respect to Certificated Notes, the Company will make all payments of
principal, premium, if any, interest and Liquidated Damages, if any, by wire
transfer of immediately available same day funds to the accounts specified by
the holders thereof or, if no such account is specified, by mailing a check to
each such holder's registered address. The Company expects that secondary
trading in the Certificated Notes will also be settled in immediately available
funds.
 
GOVERNING LAW; CONSENT TO JURISDICTION AND SERVICE
 
     The Indenture, the Notes and the Subsidiary Guarantees are governed by the
laws of the State of New York, without regard to the principles of conflicts of
laws.
 
     The Company has appointed CT Corporation as the Company's agent for service
of process in any suit, action or proceeding with respect to the Indenture, the
Notes or the Subsidiary Guarantees and for any actions brought under U.S.
federal or state securities laws brought in any U.S. federal or state court
located in the City of New York and has agreed to submit to such jurisdiction.
 
CERTAIN DEFINITIONS
 
     Set forth below are certain defined terms used in the Indenture and the
foregoing summary of the terms of the Notes. Reference is made to the Indenture
for a full disclosure of all such terms, as well as any other capitalized terms
used herein for which no definition is provided.
 
                                       87
<PAGE>   89
 
     "Acquired Indebtedness" means, with respect to any specified Person, (i)
Indebtedness of any other Person existing at the time such other Person is
merged with or into or became a Restricted Subsidiary or is designated a
Restricted Subsidiary of such specified Person, including, without limitation,
Indebtedness incurred in connection with, or in contemplation of, such other
Person merging with or into or becoming a Restricted Subsidiary of such
specified Person, and (ii) Indebtedness secured by a Lien encumbering any asset
acquired by such specified Person.
 
     "Adjusted Consolidated Net Tangible Assets" means (without duplication), as
of the date of determination, (A) the sum of (i) discounted future net cash
flows from proved oil and gas reserves of the Company and its Restricted
Subsidiaries, calculated in accordance with Commission guidelines (before any
federal or state income tax), as estimated by independent petroleum engineers as
of a date no earlier than the date of the Company's latest annual consolidated
financial statements (or, in the case that the date of determination is after
the end of the first fiscal quarter of the Company's the fiscal year, as
estimated by the Company's engineers as of a date no earlier than the end of the
most recent fiscal quarter, which estimates shall be confirmed in writing by a
report by independent petroleum engineers in accordance with Commission
guidelines in the event of a Material Change if the amount of Adjusted
Consolidated Net Tangible Assets is required to be computed under the
Indenture), (ii) the Net Working Capital on a date no earlier than the date of
the Company's latest consolidated annual or quarterly financial statements, and
(iii) with respect to each other tangible asset of the Company or its Restricted
Subsidiaries, the greater of (a) the net book value of such other tangible asset
on a date no earlier than the date of the Company's latest consolidated annual
or quarterly financial statements, and (b) (A) the appraised value, as estimated
by a qualified independent appraiser, of such other tangible asset, as of a date
no earlier than the date that is three years prior to the date of determination
(or such later date on which the Company shall have a reasonable basis to
believe that there has occurred a material decrease in value since the
determination of such appraised value), minus (B) minority interests.
 
     "Affiliate" of any specified Person means any other Person directly or
indirectly controlling or controlled by or under direct or indirect common
control with such specified Person. For purposes of this definition, "control"
(including, with correlative meanings, the terms "controlling," "controlled by"
and "under common control with"), as used with respect to any Person, shall mean
the possession, directly or indirectly, of the power to direct or cause the
direction of the management or policies of such Person, whether through the
ownership of voting securities, by agreement or otherwise; provided that
beneficial ownership of 10% or more of the voting securities of a Person shall
be deemed to be control.
 
     "Asset Sale" means (i) the sale, lease, conveyance or other disposition of
any assets (including, without limitation, by way of a sale and leaseback,
including any disposition by means of a merger, consolidation or similar
transaction and including the issuance, sale or other transfer of any of the
capital stock of any Restricted Subsidiary of such person) other than to the
Company or to any of its Wholly Owned Subsidiaries (including the receipt of
proceeds of insurance paid on account of the loss of or damage to any asset and
awards of compensation for any asset taken by condemnation, eminent domain or
similar proceeding, but excluding the receipt of proceeds of business
interruption insurance or environmental damage insurance or similar types of
policies) that have a fair market value (as determined in good faith by the
Board of Directors) in excess of $1.0 million or for net cash proceeds in excess
of $1.0 million; and (ii) the issuance of Equity Interests in any Restricted
Subsidiary or Unrestricted Subsidiary or the sale of any Equity Interests in any
Restricted Subsidiary or Unrestricted Subsidiary, in each case, in one or a
series of related transactions, provided, that notwithstanding the foregoing,
the term "Asset Sale" shall not include: (a) the sale, lease, conveyance,
disposition or other transfer of all or substantially all of the assets of the
Company, as permitted pursuant to the covenant described under "Merger,
Consolidation or Sale of Assets," (b) the abandonment, farmout, lease or
sublease of developed or undeveloped oil and gas properties in the ordinary
course of business, (c) a transfer of assets by the Company to a Wholly Owned
Subsidiary of the Company or by a Wholly Owned Subsidiary of the Company to the
Company or to another Wholly Owned Subsidiary of the Company, (d) an issuance of
Equity Interests by a Wholly Owned Subsidiary of the Company to the Company or
to another Wholly Owned Subsidiary of the Company, (e) the making of Permitted
Investments, (f) any cash dividend, distribution, Investment or payment made
pursuant to the first or second paragraph of
 
                                       88
<PAGE>   90
 
the "Restricted Payments" covenant, (g) the trade or exchange by the Company or
any Restricted Subsidiary of the Company of any oil and gas property or interest
therein owned or held by the Company or such Restricted Subsidiary for any oil
and gas property or interest therein owned or held by another Person, including
any cash or Cash Equivalents necessary in order to achieve an exchange of
equivalent value; provided that any such cash or Cash Equivalents received by
the Company or such Restricted Subsidiary will be subject to the provisions
described in the second paragraph under "-- Repurchase at the Option of
Holders -- Asset Sales," which the Board of Directors of the Company determine
in good faith to be of approximately equivalent value, (h) the sale or transfer
of hydrocarbons or other mineral products or surplus or obsolete equipment in
the ordinary course of business, (i) the sale of oil and gas properties in
connection with tax credit transactions complying with sec. 29 of the Internal
Revenue Code or (j) the sale or transfer (whether or not in the ordinary course
of business) of any oil and gas property or interest therein to which no proved
reserves are attributable at the time of such sale or transfer.
 
     "Attributable Debt" in respect of a sale and leaseback transaction means,
at the time of determination, the present value (discounted at the rate of
interest implicit in such transaction, determined in accordance with GAAP) of
the obligation of the lessee for net rental payments during the remaining term
of the lease included in such sale and leaseback transaction (including any
period for which such lease has been extended or may, at the option of the
lessor, be extended, to the extent the lease payments during such extension
period are required to be capitalized on a balance sheet as a liability in
accordance with GAAP).
 
     "Board of Directors" means the Board of Directors of the Company, or any
authorized committee of the Board of Directors.
 
     "Business Day" means any day other than a Legal Holiday.
 
     "Capital Lease Obligation" means, at the time any determination thereof is
to be made, the amount of the liability in respect of a capital lease that would
at such time be required to be capitalized on a balance sheet in accordance with
GAAP.
 
     "Capital Stock" means (i) in the case of a corporation, corporate stock,
(ii) in the case of a limited liability company or similar entity, any
membership or similar interests therein, (iii) in the case of an association or
business entity, any and all shares, interests, participations, rights or other
equivalents (however designated) of corporate stock, (iv) in the case of a
partnership, partnership interests (whether general or limited) and (v) any
other interest or participation that confers on a Person the right to receive a
share of the profits and losses of, or distributions of assets of, the issuing
Person.
 
     "Cash Equivalents" means (i) securities issued or directly and fully
guaranteed or insured by the United States government or any agency or
instrumentality thereof having maturities of not more than one year from the
date of acquisition, (ii) certificates of deposit and eurodollar time deposits
with maturities of one year or less from the date of acquisition, bankers'
acceptances with maturities not exceeding one year and overnight bank deposits,
in each case with any domestic commercial bank having capital and surplus in
excess of $500 million, (iii) repurchase obligations with a term of not more
than seven days for underlying securities of the types described in clauses (i)
and (ii) above entered into with any financial institution meeting the
qualifications specified in clause (ii) above, (iv) commercial paper having a
rating of at least P1 from Moody's Investors Service, Inc. (or its successor) or
a rating of at least A1 from Standard & Poor's Ratings Services (or its
successor) and (v) investments in money market or other mutual funds all of
whose assets comprise securities of types described in clauses (i) through (iv)
above.
 
     "Commission" means the Securities and Exchange Commission.
 
     "Consolidated Cashflow" means, with respect to the Company and its
Restricted Subsidiaries for any period, the sum of, without duplication, (i) the
Consolidated Net Income for such period, plus (ii) to the extent deducted from
Consolidated Net Income for such period, the Fixed Charges for such period plus
(iii) Consolidated Income Taxes for such period, plus (iv) consolidated
depreciation, amortization, depletion and other non-cash charges of the Company
and its Restricted Subsidiaries required to be reflected as expenses on the
books and records of the Company, and (v) excluding the impact of foreign
currency translations. Notwithstanding the foregoing, Consolidated Income Taxes
of, and the depreciation, depletion
                                       89
<PAGE>   91
 
and amortization and other non-cash charges of, a Restricted Subsidiary of a
Person shall be added to Consolidated Net Income to compute Consolidated
Cashflow only to the extent that the Net Income of such Restricted Subsidiary
was included in calculating the Consolidated Net Income of such Person and only
if a corresponding amount would be permitted at the date of determination to be
dividended to the Company by such Restricted Subsidiary without prior approval
(that has not been obtained), pursuant to the terms of its charter and all
agreements, instruments, judgments, decrees, orders, statutes, rules and
governmental regulations applicable to that Restricted Subsidiary or its
stockholders.
 
     "Consolidated Income Taxes" means, with respect to any Person for any
period, taxes imposed upon such Person or other payments required to be made by
such Person by any governmental authority which taxes or other payments are
calculated by reference to the income or profits of such Person or such Person
and its Subsidiaries (to the extent such income or profits were included in
computing Consolidated Net Income for such period), regardless of whether such
taxes or payments are required to be remitted to any governmental authority.
 
     "Consolidated Net Income" means, with respect to any Person for any period,
the aggregate of the Net Income of such Person and its Restricted Subsidiaries
for such period, on a consolidated basis, determined in accordance with GAAP;
provided that (i) the Net Income (but not loss) of any Person that is not a
Restricted Subsidiary or that is accounted for by the equity method of
accounting shall be included only to the extent of the amount of dividends or
distributions paid in cash to the referent Person or a Restricted Subsidiary
thereof, (ii) the Net Income of, or any dividends or other distributions from,
any Unrestricted Subsidiary, to the extent otherwise included, shall be
excluded, whether or not distributed to the Company or one of its Restricted
Subsidiaries, (iii) the Net Income of any Restricted Subsidiary shall be
excluded to the extent that the declaration or payment of dividends or similar
distributions by that Restricted Subsidiary of that Net Income is not at the
date of determination permitted without any prior governmental approval (which
has not been obtained) or, directly or indirectly, by operation of the terms of
its charter or any agreement, instrument, judgment, decree, order, statute, rule
or governmental regulation applicable to that Restricted Subsidiary or its
stockholders, (iv) the Net Income of any Person acquired in a pooling of
interests transaction for any period prior to the date of such acquisition shall
be excluded, and (v) the cumulative effect of a change in accounting principles
shall be excluded.
 
     "Credit Agreement" means, collectively, (i) that certain Credit Agreement,
as in effect on the date of the Indenture, by and among the Company, the lenders
that may be from time to time parties thereto and Chase Bank of Texas, National
Association (formerly known as Texas Commerce Bank National Association), as
agent, as the foregoing may from time to time be amended, renewed, supplemented
or otherwise modified at the option of the parties thereto, including increases
in the principal amount thereof; and (ii) any successors to or replacements of
(as designated by the Board of Directors of the Company in its sole judgment,
and evidenced by a resolution) such Credit Agreement, as such successors or
replacements may from time to time be amended, renewed, supplemented, modified
or replaced, including increases in the principal amount thereof.
 
     "Default" means any event that is or with the passage of time or the giving
of notice or both would be an Event of Default.
 
     "Depositary" means, with respect to the Notes issuable or issued in whole
or in part in global form, the Person specified in the Indenture as the
Depositary with respect to the Notes, until a successor shall have been
appointed and become such Depositary pursuant to the applicable provision of the
Indenture, and, thereafter, "Depositary" shall mean or include such successor.
 
     "Designated Senior Debt" means (i) the Credit Agreement and (ii) any Senior
Debt permitted under the Indenture which, at the date of determination, has an
aggregate principal amount outstanding of, or under which, at the date of
determination, the holders thereof are committed to lend up to, at least $25
million and is specifically designated by the Company in the instrument
evidencing or governing such Senior Debt as "Designated Senior Debt" for
purposes of the Indenture.
 
                                       90
<PAGE>   92
 
     "Disqualified Stock" means any Capital Stock that, by its terms (or by the
terms of any security into which it is convertible or for which it is
exchangeable) or upon the happening of any event, matures or is mandatorily
redeemable (other than in connection with a Change of Control or Asset Sale) for
any consideration other than Capital Stock, pursuant to a sinking fund
obligation or otherwise, is convertible or is exchangeable for Indebtedness or
Disqualified Stock or redeemable (other than in connection with a Change of
Control or Asset Sale) for any consideration other than Capital Stock at the
option of the holder thereof, in whole or in part, in each case on or prior to
the date that is 91 days after (x) the date on which the Notes mature or (y) on
which there are no Notes outstanding.
 
     "Dollar-Denominated Production Payments" means production payment
obligations recorded as liabilities in accordance with GAAP, together with all
undertakings and obligations in connection therewith.
 
     "Equity Interests" means Capital Stock and all warrants, options or other
rights to acquire Capital Stock (but excluding any debt security that is
convertible into, or exchangeable for, Capital Stock).
 
     "Equity Offering" means any public or private offering (other than on Form
S-8 or any other form relating to securities issuable under any benefit plan of
the Company) of Equity Interests other than Disqualified Stock of the Company or
any successor by merger to the Company.
 
     "Exchange Act" means the Securities Exchange Act of 1934, as amended.
 
     "Exchange Offer" means the offer that may be made by the Company pursuant
to the Registration Rights Agreement to exchange new Notes for Notes.
 
     "Existing Indebtedness" means the Indebtedness of the Company and its
Restricted Subsidiaries (other than Indebtedness under the Credit Agreement) in
existence on the date of the Indenture, until such amounts are repaid.
 
     "Fixed Charges" means, with respect to any Person for any period, the sum,
without duplication, of (i) the consolidated interest expense of such Person and
its Restricted Subsidiaries for such period, whether paid or accrued (including,
without limitation, amortization of original issue discount, non-cash interest
payments, the interest component of any deferred payment obligations, the
interest component of all payments associated with Capital Lease Obligations,
commissions, discounts and other fees and charges incurred in respect of letter
of credit or bankers' acceptance financings, and net payments (if any) pursuant
to Hedging Obligations), and (ii) the consolidated interest expense of such
Person and its Restricted Subsidiaries that was capitalized during such period,
and (iii) any interest expense on Indebtedness of another Person that is
guaranteed by such Person or one of its Restricted Subsidiaries or secured by a
Lien on assets of such Person or one of its Restricted Subsidiaries (whether or
not such guarantee or Lien is called upon), and (iv) the product of (a) all
dividend payments, whether or not in cash (other than any such non-cash dividend
in the form of Equity Interests which do not provide for the payment of cash
dividends prior to any stated maturity of the principal of the Notes), on any
series of preferred stock of any such Person or one of its Restricted
Subsidiaries payable to a party other than the Company or a Wholly Owned
Subsidiary, times (b) a fraction, the numerator of which is one and the
denominator of which is one minus the then current combined federal, state,
provincial and local statutory tax rate of such Person, expressed as a decimal,
in each case, on a consolidated basis and in accordance with GAAP.
 
     "Fixed Charge Coverage Ratio" means with respect to any Person for any
period, the ratio of the Consolidated Cashflow of such Person and its Restricted
Subsidiaries for such period to the Fixed Charges of such Person and its
Restricted Subsidiaries for such period. In the event that the Company or any of
its Restricted Subsidiaries incurs, assumes, guarantees, redeems or repays any
Indebtedness (other than the incurrence or repayment of revolving credit
borrowings used for working capital, except to the extent that a repayment is
accompanied by a permanent reduction in revolving credit commitments) or issues
preferred stock subsequent to the commencement of the four-quarter reference
period for which the Fixed Charge Coverage Ratio is being calculated but prior
to the date on which the event for which the calculation of the Fixed Charge
Coverage Ratio is made (the "Calculation Date"), then the Fixed Charge Coverage
Ratio shall be calculated giving pro forma effect to such incurrence,
assumption, guarantee, redemption or repayment of Indebtedness, or such issuance
or redemption of preferred stock, as if the same had occurred at the beginning
                                       91
<PAGE>   93
 
of the applicable four-quarter reference period. For purposes of making the
computation referred to above, (i) acquisitions that have been made by the
Company or any of its Restricted Subsidiaries, including through mergers or
consolidations and including any related financing transactions, during the
four-quarter reference period or subsequent to such reference period and on or
prior to the Calculation Date shall be deemed to have occurred on the first day
of the four-quarter reference period and shall give pro forma effect to the
Consolidated Cashflow and Indebtedness and preferred stock of the Person which
is the subject of any such acquisition and any cost savings or expense
reductions attributable at the time of such computation or to be attributable in
the future to such acquisition, shall be included in such computation, to the
extent that such adjustments would be permitted under Article 11 of Regulation
S-X and Consolidated Cashflow for such reference period shall be calculated
without giving effect to clause (iv) of the proviso set forth in the definition
of Consolidated Net Income, (ii) the net proceeds of Indebtedness incurred or
Disqualified Stock issued by the referent Person pursuant to the first paragraph
of the covenant described under the caption "-- Certain Covenants -- Incurrence
of Indebtedness and Issuance of Preferred Stock" during the four-quarter
reference period or subsequent to such reference period and on or prior to the
Calculation Date shall be deemed to have been received by the referent Persons
or any of its Restricted Subsidiaries on the first day of the four-quarter
reference period and applied to its intended use on such date, (iii) the
Consolidated Cashflow attributable to discontinued operations, as determined in
accordance with GAAP, and operations or businesses disposed of prior to the
Calculation Date, shall be excluded, and (iv) the Fixed Charges attributable to
discontinued operations, as determined in accordance with GAAP, and operations
or businesses disposed of prior to the Calculation Date, shall be excluded, but
only to the extent that the obligations giving rise to such Fixed Charges will
not be obligations of the referent Person or any of its Restricted Subsidiaries
following the Calculation Date.
 
     "GAAP" means generally accepted accounting principles set forth in the
opinions and pronouncements of the Accounting Principles Board of the American
Institute of Certified Public Accountants and statements and pronouncements of
the Financial Accounting Standards Board or in such other statements by such
other entity as have been approved by a significant segment of the accounting
profession, which are in effect on the date of the Indenture.
 
     "Government Securities" means direct obligations of, or obligations
guaranteed by, the United States of America for the payment of which guarantee
or obligations the full faith and credit of the United States is pledged.
 
     "Hedging Obligations" means, with respect to any Person, the obligations of
such Person under (i) interest rate or currency exchange swap agreements,
interest rate or currency exchange cap agreements and interest rate or currency
exchange collar agreements and (ii) other agreements or arrangements designed to
protect such Person against fluctuations in currency exchange or interest rates.
 
     "Holder" means a Person in whose name a Note is registered on the
Registrar's books.
 
     "Indebtedness" means, with respect to any Person, without duplication, any
indebtedness of such Person, whether or not contingent, in respect of borrowed
money or evidenced by bonds, notes, debentures or similar instruments or letters
of credit (or reimbursement agreements in respect thereof) or banker's
acceptances or representing Capital Lease Obligations or in respect of any
Production Payment or the balance deferred and unpaid of the purchase price of
any property or representing any Hedging Obligations, except any such balance
that constitutes an accrued expense or trade payable, if and to the extent any
of the foregoing indebtedness (other than in the case of letters of credit and
Hedging Obligations) would appear as a liability upon a balance sheet of such
Person prepared in accordance with GAAP, as well as all indebtedness of others
secured by a Lien on any asset of such Person (whether or not such indebtedness
is assumed by such Person), the maximum fixed repurchase price of Disqualified
Stock issued by such Person in each case, if held by any Person other than the
Company or a Wholly Owned Subsidiary of the Company, obligations of such Person
in respect of production imbalances, Attributable Debt of such Person, and, to
the extent not otherwise included, the guarantee by such Person of any
indebtedness of any other Person; provided, however that indebtedness shall not
include gas balancing liabilities incurred in the ordinary course of business
and consistent with past practice.
 
                                       92
<PAGE>   94
 
     "Investment Grade Status," with respect to the Company, shall occur when
the Notes receive a rating of "BBB-" or higher from Standard & Poor's Ratings
Group or a rating of "Baa3" or higher from Moody's Investors Service, Inc.
 
     "Investments" means, with respect to any Person, all investments by such
Person in other Persons (including Affiliates) in the forms of direct or
indirect loans (including guarantees of Indebtedness or other obligations, but
excluding trade credit), advances or capital contributions (excluding
commission, travel, relocation and similar advances to officers and employees
made in the ordinary course of business), purchases or other acquisitions for
consideration of Indebtedness, Equity Interests or other securities and all
other items that are or would be classified as investments on a balance sheet
prepared in accordance with GAAP; provided that (i) Hedging Obligations, (ii)
hedging agreements that such Person entered into in the ordinary course of
business in the oil and gas industry for the purpose of protecting against
fluctuations in oil or natural gas prices and otherwise in compliance with the
Indenture, (iii) endorsements of negotiable instruments and documents in the
ordinary course of business, (iv) Permitted Marketing Transactions and (v) an
acquisition of assets, Equity Interests or other securities by the Company for
consideration consisting of common equity securities of the Company shall not be
deemed to be an Investment. If the Company or any Restricted Subsidiary of the
Company sells or otherwise disposes of any Equity Interests of any direct or
indirect Restricted Subsidiary of the Company such that, after giving effect to
any such sale or disposition, such entity is no longer a Subsidiary of the
Company, the Company shall be deemed to have made an Investment on the date of
any such sale or disposition equal to the fair market value of the Equity
Interests of such Subsidiary not sold or disposed of.
 
     "Issue Date" means the closing date for the sale and original issuance of
the Notes under the Indenture.
 
     "Legal Holiday" means a Saturday, a Sunday or a day on which federal
offices or banking institutions in the City of New York, in the city of the
Corporate Trust Office of the Trustee, or at a place of payment are authorized
by law, regulation or executive order to remain closed. If a payment date is a
Legal Holiday, payment may be made on the next succeeding day that is not a
Legal Holiday, and no interest shall accrue for the intervening period.
 
     "Lien" means, with respect to any asset, any mortgage, lien, pledge,
charge, security interest or encumbrance of any kind in respect of such asset,
whether or not filed, recorded or otherwise perfected under applicable law
(including any conditional sale or other title retention agreement, any lease in
the nature thereof, any option or other agreement to sell or give a security
interest in and any filing of or agreement to give any financing statement under
the Uniform Commercial Code (or equivalent statutes) of any jurisdiction).
 
     "Liquidated Damages" means all liquidated damages owing pursuant to the
Registration Rights Agreement.
 
     "Material Change" means an increase or decrease of more than 20% during a
fiscal quarter in the discounted future net cash flows calculated in accordance
with Commission guidelines (excluding changes that result solely from changes in
prices) from proved oil and gas reserves of the Company and its Restricted
Subsidiaries (before any federal or state income tax); provided, however, that
the following will be excluded from the Material Change calculation: (i) any
acquisitions during the quarter of oil and gas reserves that have been estimated
by independent petroleum engineers and on which a report or reports exist, (ii)
any reserves added during the quarter attributable to the drilling or
recompletion of wells not included in previous reserve estimates, but which will
be included in future quarters, and (iii) any disposition of properties existing
at the beginning of such quarter that have been disposed of as provided in
"-- Repurchase at the Option of Holders -- Asset Sales".
 
     "Net Income" means, with respect to any Person, the net income (loss) of
such Person, determined in accordance with GAAP, and before reduction for
non-cash preferred stock dividends, excluding, however, (i) any gain or loss,
together with any related provision for taxes on such gain or loss, realized in
connection with (a) any Asset Sale (including, without limitation, dispositions
pursuant to sale and leaseback transactions) or (b) the disposition of any
securities by such Person or any of its Restricted Subsidiaries or the
extinguishment of any Indebtedness of such Person or any of its Restricted
Subsidiaries and (ii) any
 
                                       93
<PAGE>   95
 
extraordinary or nonrecurring gain or loss, together with any related provision
for taxes on such extraordinary or nonrecurring gain or loss.
 
     "Net Proceeds" means the aggregate cash proceeds received by the Company or
any of its Restricted Subsidiaries in respect of any Asset Sale (including,
without limitation, any cash received upon the sale or other disposition of any
non-cash consideration received in any Asset Sale), net of the direct costs
relating to such Asset Sale (including, without limitation, legal, accounting
and investment banking fees, and sales commissions) and any relocation expenses
incurred as a result thereof, taxes paid or payable as a result thereof (after
taking into account any available tax credits or deductions and any tax sharing
arrangements), and any reserve for adjustment in respect of the sale price of
such asset or assets established in accordance with GAAP and net of any amounts
required to be applied to the repayment of Indebtedness (other than Indebtedness
under any Senior Debt) secured by a Lien on the asset or assets that were the
subject of such Asset Sale.
 
     "Net Working Capital" means (i) all current assets of the Company and its
Restricted Subsidiaries excluding cash and Cash Equivalents, minus (ii) all
current liabilities of the Company and its Restricted Subsidiaries, except
current liabilities included in Indebtedness.
 
     "Non-Recourse Debt" means Indebtedness (i) as to which neither the Company
nor any of its Restricted Subsidiaries (a) provides any guarantee or credit
support of any kind (including any undertaking, guarantee, indemnity, agreement
or instrument that would constitute Indebtedness) or (b) is directly or
indirectly liable (as a guarantor or otherwise), (ii) no default with respect to
which (including any rights that the Holders thereof may have to take
enforcement action against an Unrestricted Subsidiary) would permit (upon
notice, lapse of time or both) any holder of any other Indebtedness of the
Company or any of its Restricted Subsidiaries to declare a default under such
other Indebtedness or cause the payment thereof to be accelerated or payable
prior to its stated maturity and (iii) the explicit terms of which provide that
there is no recourse against any of the assets of the Company or its Restricted
Subsidiaries.
 
     "Note Custodian" means the Trustee, as custodian with respect to the Global
Notes, or any successor entity thereto.
 
     "Obligations" means any principal, interest, penalties, fees,
indemnifications, reimbursements, damages and other liabilities payable under
the documentation governing any Indebtedness.
 
     "Officer" means, with respect to any Person, the Chairman of the Board, the
Chief Executive Officer, the President, the Chief Operating Officer, the Chief
Financial Officer, the Treasurer, any Assistant Treasurer, the Controller, the
Secretary or any Vice President of such Person.
 
     "Oil and Gas Business" means (i) the acquisition, exploration,
exploitation, development, operation or disposition of interests in oil, gas or
other hydrocarbon properties, (ii) the gathering, marketing, treating,
processing, storage, selling, transporting or refining of any production from
such interests or properties, (iii) any business relating to or arising from
exploration for or development, production, gathering, marketing, treatment,
processing, storage, sale, transportation or refining of oil, gas and other
minerals and products produced in association therewith or (iv) any activity
that is ancillary or necessary or desirable to facilitate the activities
described in clauses (i) through (iii) of this definition.
 
     "Pari Passu Indebtedness" means Indebtedness that ranks pari passu in right
of payment to the Notes.
 
     "Permitted Investments" means (a) any Investments in the Company or in a
Restricted Subsidiary of the Company that is engaged in the Oil and Gas
Business; (b) any Investments in Cash Equivalents; (c) Investments by the
Company or any Restricted Subsidiary of the Company in a Person if as a result
of such Investment (i) such Person becomes a Wholly Owned Subsidiary of the
Company and such Person is engaged in the Oil and Gas Business or (ii) such
Person is merged, consolidated or amalgamated with or into, or transfers or
conveys substantially all of its assets to, or is liquidated into, the Company
or a Wholly Owned Subsidiary of the Company that is engaged in the Oil and Gas
Business; (d) Investments made as a result of the receipt of non-cash
consideration from an Asset Sale that was made pursuant to and in compliance
with the covenant described under "-- Repurchase at the Option of
Holders -- Asset Sales"; (e) Investments by the Company or any of its Restricted
Subsidiaries in cash in an aggregate amount not to exceed $10.0 million
 
                                       94
<PAGE>   96
 
outstanding at any one time; (f) loans and advances to employees in the ordinary
course of business for bona fide business purposes; (g) stock, obligations or
securities received in settlement of debts created in the ordinary course of
business and owing to the Company or any of its Subsidiaries or in satisfaction
of judgments or pursuant to any plan of reorganization or similar arrangement
upon the bankruptcy or insolvency of any debtor; (h) any operating agreements,
joint ventures, partnership agreements, working interests, royalty interests,
mineral leases, processing agreements, farm-in agreements, farm-out agreements,
contracts for the sale, transportation or exchange of oil and natural gas,
unitization agreements, pooling arrangements, area of mutual interest
agreements, production sharing agreements or other similar or customary
agreements, transactions, properties, interests, or arrangements, and
Investments and expenditures in connection therewith or pursuant thereto, in
each case made or entered into in the ordinary course of the Oil and Gas
Business, excluding, however, Investments in corporations; (i) accounts
receivable created or acquired, and prepaid expenses arising, in the ordinary
course of business; (j) Investments existing on the date of the Indenture; and
(k) the incurrence, assumption or creation of Hedging Obligations and hedging
arrangements that the Company or a Restricted Subsidiary of the Company enter
into in the ordinary course of business in the oil and gas industry for the
purpose of protecting its production against fluctuations in oil or natural gas
prices and otherwise in compliance with the Indenture.
 
     "Permitted Liens" means (i) Liens securing Indebtedness of a Subsidiary or
Liens securing Senior Debt that is outstanding on the date of issuance of the
Notes and Liens securing Senior Debt that is permitted by the terms of the
Indenture to be incurred; (ii) Liens in favor of the Company or any Restricted
Subsidiary; (iii) Liens on property existing at the time of acquisition thereof
by the Company or any Subsidiary of the Company and Liens on property or assets
of a Subsidiary existing at the time it became a Subsidiary, provided that such
Liens were in existence prior to the contemplation of the acquisition and do not
extend to any assets other than the acquired property or the property of the
acquired subsidiary; (iv) Liens incurred or deposits made in the ordinary course
of business in connection with workers' compensation, unemployment insurance or
other kinds of social security, or to secure the payment or performance of
tenders, statutory or regulatory obligations, surety or appeal bonds,
performance bonds or other obligations of a like nature incurred in the ordinary
course of business (including lessee or operator obligations under statutes,
governmental regulations or instruments related to the ownership, exploration
and production of oil, gas and minerals on state or federal lands or waters);
(v) Liens existing on the date of the Indenture; (vi) Liens for taxes,
assessments or governmental charges or claims that are not yet delinquent or
that are being contested in good faith by appropriate proceedings promptly
instituted and diligently concluded, provided that any reserve or other
appropriate provision as shall be required in conformity with GAAP shall have
been made therefor; (vii) statutory liens of landlords, mechanics, suppliers,
vendors, warehousemen, carriers or other like Liens arising in the ordinary
course of business; (viii) prejudgment liens and judgment Liens not giving rise
to an Event of Default so long as any appropriate legal proceeding that may have
been duly initiated for the review of such judgment shall not have been finally
terminated or the period within which such proceeding may be initiated shall not
have expired; (ix) Liens on, or related to, properties or assets to secure all
or part of the costs incurred in the ordinary course of the Oil and Gas Business
for the exploration, drilling, development, production, processing,
transportation, marketing, storage or operation thereof; (x) Liens on pipeline
or pipeline facilities that arise under operation of law; (xi) Liens arising
under operating agreements, joint venture agreements, partnership agreements,
oil and gas leases, farm-in agreements, farm-out agreements, division orders,
contracts for the sale, transportation or exchange of oil or natural gas,
unitization and pooling declarations and agreements, area of mutual interest
agreements and other agreements that are customary in the Oil and Gas Business;
(xii) Liens reserved in oil and gas mineral leases for bonus or rental payments
and for compliance with the terms of such leases, (xiii) Liens securing the
Notes; (xiv) Liens constituting survey exceptions, encumbrances, easements, and
reservations of, and rights to others for, rights-of-way, zoning and other
restrictions as to the use of real properties, and minor defects of title which,
in the case of any of the foregoing, do not secure the payment of borrowed
money, and in the aggregate do not materially adversely affect the value of the
assets of the Company and its Restricted Subsidiaries, taken as a whole, or
materially impair the use of such properties for the purposes of which such
properties are held by the Company or such subsidiaries; and (xv) Liens not
otherwise permitted by clauses (i) through (xiv) that are incurred in the
 
                                       95
<PAGE>   97
 
ordinary course of business of the Company or any Subsidiary with respect to
obligations that do not exceed $5 million at any one time outstanding.
 
     "Permitted Marketing Transaction" means (i) a transaction in which the
Company or any Subsidiary of the Company either (a) establishes a position using
New York Mercantile Exchange Crude Oil or Natural Gas Futures contracts to
purchase hydrocarbons for future delivery to it or (b) purchases or commits to
purchase hydrocarbons for future delivery to it, and contemporaneous with such
purchase transaction either (1) establishes one or more positions using New York
Mercantile Exchange Crude Oil or Natural Gas Futures contracts to resell at a
date subsequent to such delivery date or (2) enters into a contract with a
Person to resell at a date subsequent to such delivery date, a similar aggregate
quantity and quality of hydrocarbons as so purchased by the Company or such
Subsidiary, as applicable, at an aggregate price greater than the Indebtedness
incurred for the hydrocarbons so purchased by the Company or such Subsidiary or
(ii) any other purchase by the Company or any Subsidiary of the Company of
hydrocarbons for which the Company or such Subsidiary has contracts to sell.
 
     "Permitted Refinancing Indebtedness" means any Indebtedness of the Company
or any of its Restricted Subsidiaries issued in exchange for, or the net
proceeds of which are used to extend, refinance, renew, replace, defease or
refund other Indebtedness of the Company or any of its Restricted Subsidiaries;
provided that (i) the principal amount (or accredited value, if applicable) of
such Permitted Refinancing Indebtedness does not exceed the original principal
amount (or then current accredited value, if applicable) of the Indebtedness so
extended, refinanced, renewed, replaced, defeased or refunded (plus the amount
of reasonable expenses incurred in connection therewith); (ii) such Permitted
Refinancing Indebtedness has a final maturity date at least as late as the final
maturity date of, and has a Weighted Average Life to Maturity equal to or
greater than the Weighted Average Life to Maturity of, the Indebtedness being
extended, refinanced, renewed, replaced, defeased or refunded; (iii) if the
Indebtedness being extended, refinanced, renewed, replaced, defeased or refunded
is subordinated in right of payment to the Notes, such Permitted Refinancing
Indebtedness has a final maturity date later than the final maturity date of,
and is subordinated in right of payment to, the Notes on terms at least as
favorable to the Holders of Notes as those contained in the documentation
governing the Indebtedness being extended, refinanced, renewed, replaced,
defeased or refunded; and (iv) such Indebtedness is incurred either by the
Company or by the Restricted Subsidiary who is the obligor on the Indebtedness
being extended, refinanced, renewed, replaced, defeased or refunded.
 
     "Person" means any individual, corporation, partnership, joint venture,
association, joint-stock company, trust, unincorporated organization, limited
liability company, or other business entity or government or agency or political
subdivision thereof (including any subdivision or ongoing business of any such
entity or substantially all of the assets of any such entity, subdivision or
business).
 
     "Production Payments" means Dollar-Denominated Production Payments and
Volumetric Production Payments, collectively.
 
     "Purchase Money Lien" means a Lien granted on an asset or property to
secure a Purchase Money Obligation permitted to be incurred under the Indenture
and incurred solely to finance the purchase, or the cost of construction or
improvement, of such asset or property; provided however, that such Lien
encumbers only such asset or property and is granted within 180 days of such
acquisition.
 
     "Purchase Money Obligations" of any Person means any obligations of such
Person to any seller or any other Person incurred or assumed to finance the
purchase, or the cost of construction or improvement, of real or personal
property to be used in the business of such Person or any of its Restricted
Subsidiaries in an amount that is not more than 100% of the cost, or fair market
value, as appropriate, of such property, and incurred within 90 days after the
date of such acquisition (excluding accounts payable to trade creditors incurred
in the ordinary course of business).
 
     "Registration Rights Agreement" means the Registration Rights Agreement,
dated as of the date of the Indenture, by and among the Company and the Initial
Purchasers, as such agreement may be amended, modified or supplemented from time
to time.
 
                                       96
<PAGE>   98
 
     "Representative" means the indenture trustee or other trustee, client or
representative for any senior Indebtedness.
 
     "Responsible Officer," when used with respect to the Trustee, means any
officer of the Trustee with direct responsibility for the administration of the
Indenture and also means, with respect to a particular corporate trust matter,
any other officer to whom such matter is referred because of his knowledge of
and familiarity with the particular subject.
 
     "Restricted Investment" means an Investment other than a Permitted
Investment.
 
     "Restricted Subsidiary" of a Person means any Subsidiary of the referent
Person that is not an Unrestricted Subsidiary.
 
     "Securities Act" means the Securities Act of 1933, as amended.
 
     "Senior Debt" means (i) indebtedness of the Company under or in respect of
the Credit Agreement, whether for principal, interest (including interest
accruing after the filing of a petition initiating any proceeding pursuant to
any bankruptcy law, whether or not the claim for such interest is allowed as a
claim in such proceeding), reimbursement obligations, fees, commissions,
expense, indemnities or other amounts, and (ii) any other Indebtedness permitted
under the terms of the Indenture, unless the instrument under which such
Indebtedness is incurred expressly provides that it is on a parity with or
subordinated in right of payment to the Notes. Notwithstanding anything to the
contrary in the foregoing sentence, Senior Debt will not include (v) Equity
Interests, (w) any liability for federal, state, local or other taxes owned or
owing by the Company, (x) any Indebtedness of the Company to any of its
Subsidiaries or other Affiliates, (y) any trade payables or (z) any Indebtedness
that is incurred in violation of the Indenture. Senior Debt of a Subsidiary
Guarantor has a correlative meaning (including interest accruing after the
filing of a petition initiating any proceeding pursuant to any bankruptcy law,
whether or not the claim for such interest is allowed as a claim in such
proceeding).
 
     "Significant Subsidiary" means any Subsidiary that would be a "significant
subsidiary" as defined in Article 1, Rule 1-02 of Regulation S-X, promulgated
pursuant to the Exchange Act, as such Regulation is in effect on the date
hereof.
 
     "Subsidiary" of any Person means any corporation, association, partnership
or other business entity of which more than 50% of the total voting power of
shares of Capital Stock or other equity interests (including partnership
interests) entitles (without regard to the occurrence of any contingency) to
vote in the election of directors, managers or trustees thereof is at the time
owned or controlled, directly or indirectly, by (i) such Person or (ii) one or
more Subsidiaries of such Person.
 
     "Subsidiary Guarantee" means any guarantee of the obligations of the
Company under the Indenture and the Notes by a Restricted Subsidiary in
accordance with the provisions of the Indenture.
 
     "Subsidiary Guarantors" means any Restricted Subsidiary that incurs a
Subsidiary Guarantee.
 
     "Trust Indenture Act" means the Trust Indenture Act of 1939 (15 U.S.C.
sec.sec. 77aaa-77bbbb) as in effect on the date on which the Indenture is
qualified under the Trust Indenture Act.
 
     "Unrestricted Subsidiary" means (i) any Subsidiary of the Company which at
the time of determination shall be an Unrestricted Subsidiary (as designated by
the Board of Directors of the Company, as provided below) and (ii) any
Subsidiary of an Unrestricted Subsidiary. The Board of Directors of the Company
may designate any Subsidiary of the Company (including any newly acquired or
newly formed Subsidiary or a Person becoming a Subsidiary through merger or
consolidation or Investment therein) to be an Unrestricted Subsidiary only if
(a) such Subsidiary does not own any Capital Stock of, or own or hold any Lien
on any property of, any other Subsidiary of the Company which is not a
Subsidiary of the Subsidiary to be so designated or otherwise an Unrestricted
Subsidiary; (b) all the Indebtedness of such Subsidiary and its Subsidiaries
shall, at the date of designation, and will at all times thereafter, consist of
NonRecourse Debt; (c) the Company certifies that such designation complies with
the limitations of the "-- Restricted Payments" covenant; (d) such Subsidiary,
either alone or in the aggregate with all other Unrestricted
 
                                       97
<PAGE>   99
 
Subsidiaries, does not operate, directly or indirectly, all or substantially all
of the business of the Company and its Subsidiaries; (e) such Subsidiary does
not, directly or indirectly, own any Indebtedness of or Equity Interest in, and
has no investments in, the Company or any Restricted Subsidiary; and (f) such
Subsidiary is a Person with respect to which neither the Company nor any of its
Restricted Subsidiaries has any direct or indirect obligation (1) to subscribe
for additional Equity Interests of such Person or (2) to maintain or preserve
such Person's financial condition or to cause such Person to achieve any
specified levels of operating results. Any such designation by the Board of
Directors of the Company shall be evidenced to the Trustee by filing with the
Trustee a resolution of the Board of Directors of the Company giving effect to
such designation and an Officers' certificate certifying that such designation
complied with the foregoing conditions. If, at any time, any Unrestricted
Subsidiary would fail to meet the foregoing requirements as an Unrestricted
Subsidiary, it shall thereafter cease to be an Unrestricted Subsidiary for
purposes of the Indenture and any Indebtedness of such Subsidiary shall be
deemed to be incurred as of such date. The Board of Directors of the Company may
designate any Unrestricted Subsidiary to be a Restricted Subsidiary; provided,
that immediately after giving effect to such designation, no Default or Event of
Default shall have occurred and be continuing or would occur as a consequence
thereof and the Company could incur at least $1.00 of additional Indebtedness
(excluding Permitted Indebtedness) pursuant to the first paragraph of the
"-- Incurrence of Indebtedness and Issuance of Preferred Stock" covenant on a
pro forma basis taking into account such designation.
 
     "Volumetric Production Payments" means production payment obligations
recorded as deferred revenue in accordance with GAAP, together with all
undertakings and obligations in connection therewith.
 
     "Voting Stock" of any entity means all classes of Capital Stock of such
entity then outstanding and normally entitled to vote in the election of
directors or all interests in such entity with the ability to control the
management or actions of such entity.
 
     "Weighted Average Life to Maturity" means, when applied to any Indebtedness
at any date, the number of years obtained by dividing (i) the sum of the
products obtained by multiplying (a) the amount of each then remaining
installment, sinking fund, serial maturity or other required payments of
principal, including payment at final maturity, in respect thereof, by (b) the
number of years (calculated to the nearest one-twelfth) that will elapse between
such date and the making of such payment, by (ii) the then outstanding principal
amount of such Indebtedness.
 
     "Wholly Owned Subsidiary" of any Person means a Restricted Subsidiary of
such Person all of the outstanding Capital Stock or other ownership interests of
which (other than directors' qualifying shares or shares required by applicable
law to be held by third parties) shall at the time be owned by such Person or by
one or more Wholly Owned Subsidiaries of such Person. Unrestricted Subsidiaries
shall not be included in the definition of Wholly Owned Subsidiary for any
purposes of the Indenture.
 
                                       98
<PAGE>   100
 
            CERTAIN UNITED STATES FEDERAL INCOME TAX CONSIDERATIONS
 
     The following is a general discussion of certain United States federal
income tax consequences resulting from the acquisition, ownership and
disposition of Notes by an initial beneficial owner of Notes. The tax treatment
of the holders of the Notes may vary depending upon their particular situations.
The legal conclusions expressed in this summary are based upon current
provisions of the Internal Revenue Code of 1986, as amended (the "Code"),
applicable Treasury regulations, judicial authority and administrative rulings,
all as in effect as of the date of this Offering Memorandum, and all of which
are subject to change, either prospectively or retroactively. These authorities
are subject to various interpretations and it is therefore possible that the tax
treatment of the Notes may differ from the treatment described below.
Legislative, judicial or administrative changes or interpretations may be
forthcoming that could alter or modify the statements and conclusions set forth
herein. Any such changes or interpretations may or may not be retroactive and
could affect the tax consequences to holders.
 
     This discussion deals only with persons who will hold the Notes as capital
assets. In addition, certain other holders (including insurance companies, tax
exempt organizations, financial institutions and broker-dealers) may be subject
to special rules not discussed below. For purposes of this discussion, a "United
States person" means a citizen or resident of the United States, a corporation,
partnership or other entity created or organized in the United States or under
the laws of the United States or of any political subdivision thereof, an estate
whose income is includible in gross income for United States federal income tax
purposes regardless of its source or a trust, if a U.S. court is able to
exercise primary supervision over the administration of the trust and one or
more United States persons have the authority to control all substantial
decisions of the trust. PROSPECTIVE INVESTORS ARE URGED TO CONSULT THEIR TAX
ADVISORS REGARDING THE UNITED STATES FEDERAL TAX CONSEQUENCES OF ACQUIRING,
HOLDING AND DISPOSING OF NOTES, AS WELL AS ANY TAX CONSEQUENCES THAT MAY ARISE
UNDER THE LAWS OF ANY FOREIGN, STATE, LOCAL OR OTHER TAXING JURISDICTION.
 
INTEREST
 
     Interest on the Notes generally will be includable in the income of a
United States person as ordinary income at the time such interest is received or
accrued, in accordance with such United States person's method of accounting for
United States federal income tax purposes. The Company expects that the Notes
will not be issued with original issue discount within the meaning of the Code.
 
EFFECT OF OPTIONAL REDEMPTION
 
     The Company, at its option, may redeem part or all of the Notes at the
times and for the amounts described in "Description of the Notes -- Optional
Redemption" herein. The Treasury regulations provide that for purposes of
calculating the yield to maturity of a debt instrument, an issuer will be
treated as exercising any option if its exercise would lower the yield of the
debt instrument. However, in this case, a redemption of the Notes at the
optional redemption prices would increase the effective yield of such Notes as
calculated from the date of issuance.
 
THE EXCHANGE OFFER
 
     Pursuant to the Treasury regulations, the exchange of Old Notes for
Exchange Notes pursuant to the Exchange Offer should not constitute a
significant modification of the terms of the Old Notes, and accordingly, such
exchange should be treated as a "non-event" for federal income tax purposes.
Therefore, such exchange should have no federal income tax consequences to
United States persons. The holding period of an Exchange Note will include the
holding period of the Old Note for which it was exchanged; the basis of an
Exchange Note will be the same as the basis of the Old Note for which it was
exchanged; and each United States person holding the Exchange Notes would
continue to be required to include interest on the Old Notes in its gross income
in accordance with its method of accounting for United States federal income tax
purposes.
 
                                       99
<PAGE>   101
 
SALES, EXCHANGE OR RETIREMENT OF NOTES
 
     Upon the sale, exchange, redemption or other disposition of a Note, other
than the exchange of an Old Note for an Exchange Note (see "-- The Exchange
Offer" above), a holder of a Note generally will recognize gain or loss in an
amount equal to the difference between the amount of cash and the fair market
value of any property received on the sale, exchange, redemption or other
disposition of the Note (other than in respect of accrued and unpaid interest on
the Note, which such amounts are treated as ordinary interest income) and such
holder's adjusted tax basis in the Note. Such gain or loss will be capital gain
or loss. An individual holder of the Note will generally recognize such gain as
long-term capital gain taxable at a rate of 20% if the Note is held for more
than 18 months, mid-term capital gain taxable at a rate of 28% if the Note is
held for 18 months or less but more than 12 months, and short-term capital gain
taxable at ordinary income tax rates if the Note is held for 12 months or less.
Subsequent to December 31, 2000, the capital gain rate would be reduced to 18%
if a Note has been held for more than five years. The deductibility of capital
losses is subject to limitation.
 
BACKUP WITHHOLDING AND INFORMATION REPORTING
 
     In general, information reporting requirements will apply to interest
payments on the Notes made to United States persons, other than certain exempt
recipients (such as corporations), and to proceeds realized by such United
States persons on dispositions of Notes. A 31% backup withholding tax will apply
to such amounts only if the United States person: (i) fails to furnish its
social security or other taxpayer identification number ("TIN") within a
reasonable time after request therefor, (ii) furnishes an incorrect TIN, (iii)
fails to report properly interest or dividend income, or (iv) fails, under
certain circumstances, to provide a certified statement, signed under penalty of
perjury, that the TIN provided is its correct number and that it is not subject
to backup withholding. Any amount withheld under the backup withholding rules
may be refunded or credited against the United States persons' United States
federal income tax liability, provided that the required information is
furnished to the Internal Revenue Service.
 
CERTAIN UNITED STATES FEDERAL INCOME TAX CONSEQUENCES APPLICABLE TO NON-UNITED
STATES HOLDERS
 
     For purposes of this discussion, a "Non-United States Holder" is an initial
beneficial owner of a Note that for United States federal income tax purposes is
not a United States person.
 
  Interest
 
     Interest paid by the Company to a Non-United States Holder will not be
subject to United States federal income or withholding tax if such interest is
not effectively connected with the conduct of a trade or business within the
United States by such Non-United States Holder and such Non-United States
Holder: (i) does not actually or constructively own 10% or more of the total
combined voting power of all classes of stock of the Company; (ii) is not a
controlled foreign corporation with respect to which the Company is a "related
person" within the meaning of the Code; (iii) is not a bank whose receipt of
interest on a Note is described in section 881(c)(3)(A) of the Code; and (iv)
certifies, under penalties of perjury, that such holder is not a United States
person and provides such holder's name and address.
 
  Sale, Exchange or Retirement of Notes
 
     A non-United States Holder will generally not be subject to United States
federal income tax on gain recognized on a sale, exchange, retirement (including
redemption) or other disposition of a Note unless: (i) the gain is effectively
connected with the conduct of a trade or business within the United States by
the Non-United States Holder; or (ii) in the case of a Non-United States Holder
who is a nonresident alien individual and holds the Note as a capital asset,
such holder is present in the United States for 183 or more days in the taxable
year and certain other requirements are met.
 
                                       100
<PAGE>   102
 
  Federal Estate Taxes
 
     If interest on the Notes is exempt from withholding of United States
federal income tax under the rules described above, the Notes will not be
included in the estate of a deceased Non-United States Holder for United States
federal estate tax purposes.
 
  Information Reporting and Backup Withholding
 
     The Company will, where required, report to the holders of Notes and the
Internal Revenue Service the amount of any interest paid on the Notes in each
calendar year and the amounts of tax withheld, if any, with respect to such
payments.
 
     In the case of payments of interest to Non-United States Holders, temporary
Treasury regulations provide that the 31% backup withholding tax and certain
information reporting will not apply to such payments with respect to which
either the requisite certification, as described above, has been received or an
exemption has otherwise been established; provided that neither the Company nor
its payment agent has actual knowledge that the holder is a United States person
or that the conditions of any other exemption are not in fact satisfied. Under
temporary Treasury regulations, these information reporting and backup
requirements will apply, however, to the gross proceeds paid to a Non-United
States Holder on the disposition of the Notes by or through a United States
office of a United States or foreign broker, unless the holder certifies to the
broker under penalties of perjury as to its name, address and status as a
foreign person or the holder otherwise establishes an exemption. Information
reporting requirements, but not backup withholding, will also apply to a payment
of the proceeds of a disposition of the Notes by or through a foreign office of
a United States broker or foreign brokers with certain types of relationships to
the United States unless such broker has documentary evidence in its file that
the holder of the Notes is not a United States person, and such broker has no
actual knowledge to the contrary, or the holder establishes an exception.
Neither information reporting or backup withholding generally will apply to a
payment of the proceeds of a disposition of the Notes by or through a foreign
office of a foreign broker not subject to the preceding sentence.
 
     United States Treasury regulations, which generally are effective for
payments made after December 31, 1999, subject to certain transition rules,
alter the foregoing rules in certain respects. Among other things, such
regulations provide presumptions under which a Non-United States Holder is
subject to information reporting and backup withholding at the rate of 31%
unless the Company receives certification from the holder of non-U.S. status.
Depending on the circumstances, this certification will need to be provided (i)
directly by the Non-United States Holder, (ii) in the case of a Non-United
States Holder that is treated as a partnership or other fiscally transparent
entity, by the partners, shareholders or other beneficiaries of such entity, or
(iii) certain qualified financial institutions or other qualified entities on
behalf of the Non-United States Holder.
 
     Backup withholding is not an additional tax. Any amounts withheld under the
backup withholding rules may be refunded or credited against the Non-United
States Holder's federal income tax liability, provided that the required
information is furnished to the Internal Revenue Service.
 
                              PLAN OF DISTRIBUTION
 
     Each broker-dealer that receives Exchange Notes for its own account
pursuant to the Exchange Offer must acknowledge that it will deliver a
prospectus in connection with any resale of such Exchange Notes. This
Prospectus, as it may be amended or supplemented from time to time, may be used
by a broker-dealer in connection with resales of Exchange Notes received in
exchange for Old Notes where such Old Notes were acquired as a result of
market-making activities or other trading activities. The Company has agreed
that it will make this Prospectus, as amended or supplemented, available to any
broker-dealer for use in connection with any such resale.
 
     The Company will not receive any proceeds from any sale of Exchange Notes
by broker-dealers. Exchange Notes received by broker-dealers for their own
account pursuant to the Exchange Offer may be sold from time to time in one or
more transactions in the over-the-counter market, in negotiated transactions,
                                       101
<PAGE>   103
 
through the writing of options on the Exchange Notes or a combination of such
methods of resale, at market prices prevailing at the time of resale, at prices
related to such prevailing market prices or at negotiated prices. Any such
resale may be made directly to purchasers or to or through brokers or dealers
who may receive compensation in the form of commissions or concessions from any
such broker-dealer or the purchasers of any such Exchange Notes. Any
broker-dealer that resells Exchange Notes that were received by it for its own
account pursuant to the Exchange Offer and any broker or dealer that
participates in a distribution of such Exchange Notes may be deemed to be an
"underwriter" within the meaning of the Securities Act and any profit on any
such resale of Exchange Notes and any commission or concessions received by any
such person may be deemed to be underwriting compensation under the Securities
Act. The Letter of Transmittal states that, by acknowledging that it will
deliver and by delivering a prospectus, a broker-dealer will not be deemed to
admit that it is an "underwriter" within the meaning of the Securities Act.
 
     The Company will promptly send additional copies of this Prospectus and any
amendment or supplement to this Prospectus to any broker-dealer that requests
such documents in the Letter of Transmittal. The Company has agreed to pay all
expenses incident to the Exchange Offer, other than commissions or concessions
of any broker-dealer, and will indemnify the holders of the Notes (including any
broker-dealers) against certain liabilities including liabilities under the
Securities Act.
 
                                 LEGAL MATTERS
 
     Certain legal matters in connection with the Exchange Notes will be passed
upon for the Company by Andrews & Kurth L.L.P., Houston, Texas.
 
                         INDEPENDENT PUBLIC ACCOUNTANTS
 
     The combined audited financial statements of the Company as of December 31,
1996 and 1997, and for each of the three years in the period ended December 31,
1997, included and incorporated by reference in this Prospectus have been
audited by Arthur Andersen LLP, independent public accountants, as indicated in
their report with respect thereto, and are included herein in reliance upon the
authority of said firm as experts in giving said report.
 
                               RESERVE ENGINEERS
 
     The reserve reports and estimates of the Company's net proved natural gas
and oil reserves included herein have been prepared by NSA, Miller and Lents,
Ryder Scott and Huddleston.
 
                             AVAILABLE INFORMATION
 
     The Company has filed with the SEC a registration statement (the
"Registration Statement") under the Securities Act on Form S-4 with respect to
the Exchange Notes offered hereby. This Prospectus does not contain all of the
information set forth in the Registration Statement and the exhibits thereto,
certain parts of which are omitted in accordance with the rules and regulations
of the SEC. Statements made in this Prospectus as to the contents of any
contract, agreement or other document referred to are not necessarily complete.
With respect to each such contract, agreement or other document filed as an
exhibit to the Registration Statement, reference is made to the exhibit for a
more complete description of the matter involved. The Registration Statement and
any amendments thereto, including exhibits filed or incorporated by reference as
a part thereof, are available for inspection and copying at the SEC's offices as
described below.
 
     The Company is subject to the informational requirements of the Exchange
Act and, in accordance therewith, files reports, proxy and information
statements and other information with the Commission. Copies of such materials
can be obtained by mail from the Public Reference Section of the Commission, at
Judiciary Plaza, 450 Fifth Street, N.W., Washington, D.C. 20549, at prescribed
rates. In addition, such reports, proxy and information statements and other
information can be inspected and copied at the public reference facility
referenced above and at the Commission's regional offices at Citicorp Center,
500 West Madison Street,
                                       102
<PAGE>   104
 
Suite 1400, Chicago, Illinois 60661-2511 and 7 World Trade Center, Suite 1300,
New York, New York 10048. The Commission maintains a web site
(http://www.sec.gov) that contains reports, proxy and information statements and
other information regarding registrants, such as the Company, that file
electronically with the Commission. In addition, for so long as any of the Notes
remains outstanding, the Company has agreed to make available to any prospective
purchaser of the Notes or beneficial owner of the Notes in connection with any
sale thereof the information required by Rule 144A(d)(4) under the Securities
Act. Any such request and requests for the agreements summarized herein should
be directed to James F. Westmoreland, Secretary, The Houston Exploration
Company, 1100 Louisiana, Suite 2000, Houston, Texas 77002, telephone number
(713) 830-6800.
 
               INCORPORATION OF CERTAIN INFORMATION BY REFERENCE
 
     The following documents filed with the Commission pursuant to the Exchange
Act is incorporated herein by reference:
 
          1. The Company's Annual Report on Form 10-K for the year ended
     December 31, 1997; and
 
          2. The Company's Current Report on Form 8-K dated February 9, 1998.
 
     All documents filed by the Company pursuant to Section 13(a), 13(c), 14 or
15(d) of the Exchange Act subsequent to the date of this Prospectus and prior to
the termination of the offering made hereby shall be deemed to be incorporated
by reference in this Prospectus and shall be deemed a part hereof from the date
of filing of such 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 Prospectus to the extent that a statement
contained herein or in any other 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,
except as so modified or superseded, to constitute a part of this Prospectus.
 
     Any statement contained in a document incorporated by reference herein
shall be deemed to be modified or superseded for all purposes to the extent that
a statement contained in this Prospectus, or in any other subsequently filed
document which is also, or is deemed to be, incorporated by reference, modifies
or replaces such statement. Any such statement so modified or superseded shall
not be deemed to constitute a part of this Prospectus, except as so modified or
superseded.
 
     The Company will provide without charge to each person to whom this
Prospectus has been delivered, on written or oral request of such person, a copy
(without exhibits, unless such exhibits are specifically incorporated by
reference into such documents) of any or all documents incorporated by reference
in this Prospectus. Requests for such copies should be addressed to: Secretary,
The Houston Exploration Company, 1100 Louisiana, Suite 2000, Houston, Texas
77002, telephone number (713) 830-6800.
 
                                       103
<PAGE>   105
 
                         GLOSSARY OF OIL AND GAS TERMS
 
     The definitions set forth below shall apply to the indicated terms as used
in this Prospectus. All volumes of natural gas referred to herein are stated at
the legal pressure base of the state or area where the reserves exist and at 60
degrees Fahrenheit and in most instances are rounded to the nearest major
multiple.
 
     Bbl. One stock tank barrel, or 42 U.S. gallons liquid volume, used herein
in reference to crude oil or other liquid hydrocarbons.
 
     Bbl/d. One barrel per day.
 
     Bcf. Billion cubic feet.
 
     Bcfe. Billion cubic feet equivalent, determined using the ratio of six Mcf
of natural gas to one Bbl of crude oil, condensate or natural gas liquids.
 
     Btu. British thermal unit, which is the heat required to raise the
temperature of a one-pound mass of water from 58.5 to 59.5 degrees Fahrenheit.
 
     Completion. The installation of permanent equipment for the production of
oil or gas, or in the case of a dry hole, the reporting of abandonment to the
appropriate agency.
 
     Developed acreage. The number of acres which are allocated or assignable to
producing wells or wells capable of production.
 
     Developed well. A well drilled within the proved area of an oil or gas
reservoir to the depth of a stratigraphic horizon known to be productive.
 
     Dry hole or well. A well found to be incapable of producing hydrocarbons in
sufficient quantities such that proceeds from the sale of such production exceed
production expenses and taxes.
 
     Exploratory well. A well drilled to find and produce oil or gas reserves
not classified as proved, to find a new reservoir in a field previously found to
be productive of oil or gas in another reservoir or to extend a known reservoir.
 
     Farm-in or farm-out. An agreement whereunder the owner of a working
interest in an natural gas and oil lease assigns the working interest or a
portion thereof to another party who desires to drill on the leased acreage.
Generally, the assignee is required to drill one or more wells in order to earn
its interest in the acreage. The assignor usually retains a royalty or
reversionary interest in the lease. The interest received by an assignee is a
"farm-in" while the interest transferred by the assignor is a "farm-out."
 
     Field. An area consisting of a single reservoir or multiple reservoirs all
grouped on or related to the same individual geological structural feature
and/or stratigraphic condition.
 
     Gross acres or gross wells. The total acres or wells, as the case may be,
in which a working interest is owned.
 
     MBbls. One thousand barrels of crude oil or other liquid hydrocarbons.
 
     MBbls/d. One thousand barrels of crude oil or other liquid hydrocarbons per
day.
 
     Mcf. One thousand cubic feet.
 
     Mcf/d. One thousand cubic feet per day.
 
     Mcfe. One thousand cubic feet equivalent, determined using the ratio of six
Mcf of natural gas to one Bbl of crude oil, condensate or natural gas liquids.
 
     Mcfe/d. One thousand cubic feet equivalent, determined using the ratio of
six Mcf of natural gas to one Bbl of crude oil, condensate or natural gas
liquids per day.
 
     MMBbls. One million barrels of crude oil or other liquid hydrocarbons.
 
     MMbtu. One million Btus.
                                       G-1
<PAGE>   106
 
     MMcf. One million cubic feet.
 
     MMcf/d. One million cubic feet per day.
 
     MMcfe. One million cubic feet equivalent, determined using the ratio of six
Mcf of natural gas to one Bbl of crude oil, condensate or natural gas liquids.
 
     Net acres or net wells. The sum of the fractional working interests owned
in gross acres or gross wells.
 
     Oil. Crude oil and condensate.
 
     Present value. When used with respect to natural gas and oil reserves, the
estimated future gross revenue to be generated from the production of proved
reserves, net of estimated production and future development costs, using prices
and costs in effect as of the date indicated, without giving effect to
non-property related expenses such as general and administrative expenses, debt
service and future income tax expenses or to depreciation, depletion and
amortization, discounted using an annual discount rate of 10%.
 
     Productive well. A well that is found to be capable of producing
hydrocarbons in sufficient quantities such that proceeds from the sale of such
production exceed production expenses and taxes.
 
     Proved developed producing reserves. Proved developed reserves that are
expected to be recovered from completion intervals currently open in existing
wells and able to produce to market.
 
     Proved developed nonproducing reserves. Proved developed reserves expected
to be recovered from zones behind casing in existing wells.
 
     Proved reserves. The estimated quantities of crude oil, natural gas and
natural gas liquids which geological and engineering data demonstrate with
reasonable certainty to be recoverable in future years from known reservoirs
under existing economic and operating conditions.
 
     Proved undeveloped location. A site on which a development well can be
drilled consistent with spacing rules for purposes of recovering proved
undeveloped reserves.
 
     Proved undeveloped reserves. Proved reserves that are expected to be
recovered from new wells on undrilled acreage or from existing wells where a
relatively major expenditure is required from recompletion.
 
     Recompletion. The completion for production of an existing well bore in
another formation from that in which the well has been previously completed.
 
     Reservoir. A porous and permeable underground formation containing a
natural accumulation of producible oil and/or gas that is confined by
impermeable rock or water barriers and is individual and separate from other
reservoirs.
 
     Royalty interest. An interest in a natural gas and oil property entitling
the owner to a share of oil or gas production free of costs of production.
 
     Undeveloped acreage. Lease acreage on which wells have not been drilled or
completed to a point that would permit the production of commercial quantities
of natural gas and oil regardless of whether such acreage contains proved
reserves.
 
     Working interest. The operating interest which gives the owner the right to
drill, produce and conduct operating activities on the property and a share of
production.
 
     Workover. Operations on a producing well to restore or increase production.
 
                                       G-2
<PAGE>   107
 
                         INDEX TO FINANCIAL STATEMENTS
 
<TABLE>
<CAPTION>
                                                              PAGE
                                                              ----
<S>                                                           <C>
Report of Independent Public Accountants....................  F-2
Combined Balance Sheets as of December 31, 1996 and 1997....  F-3
Combined Statements of Operations for the Years Ended
  December 31, 1995, 1996 and 1997..........................  F-4
Combined Statement of Stockholders' Equity for the Years
  Ended December 31, 1995, 1996 and 1997....................  F-5
Combined Statements of Cash Flows for the Years Ended
  December 31, 1995, 1996 and 1997..........................  F-6
Notes to Combined Financial Statements......................  F-7
</TABLE>
 
                                       F-1
<PAGE>   108
 
                    REPORT OF INDEPENDENT PUBLIC ACCOUNTANTS
 
     We have audited the accompanying combined balance sheets of The Houston
Exploration Company (a Delaware corporation and an indirect 65%-owned subsidiary
of KeySpan Energy Corporation) as of December 31, 1996 and 1997, and the related
combined statements of operations, stockholders' equity and cash flows for each
of the three years in the period ended December 31, 1997. These financial
statements are the responsibility of the Company's management. Our
responsibility is to express an opinion on these financial statements based on
our audits.
 
     We conducted our audits in accordance with generally accepted auditing
standards. Those standards require that we plan and perform the audit to obtain
reasonable assurance about whether the financial statements are free of material
misstatement. An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements. An audit also includes
assessing the accounting principles used and significant estimates made by
management, as well as evaluating the overall financial statement presentation.
We believe that our audits provide a reasonable basis for our opinion.
 
     In our opinion, the combined financial statements referred to above present
fairly, in all material respects, the financial position of The Houston
Exploration Company, as of December 31, 1996 and 1997, and the results of its
operations and its cash flows for each of the three years in the period ended
December 31, 1997, in conformity with generally accepted accounting principles.
 
                                            ARTHUR ANDERSEN LLP
 
New York, New York
January 27, 1998
 
                                       F-2
<PAGE>   109
 
                        THE HOUSTON EXPLORATION COMPANY
 
                            COMBINED BALANCE SHEETS
 
<TABLE>
<CAPTION>
                                                                  DECEMBER 31,
                                                              --------------------
                                                                1996        1997
                                                              --------    --------
                                                                 (IN THOUSANDS)
<S>                                                           <C>         <C>
ASSETS:
Cash and cash equivalents...................................  $  2,851    $  4,745
Accounts receivable.........................................    35,845      37,898
Accounts receivable -- Brooklyn Union.......................        --       1,303
Inventories.................................................       992       1,265
Prepayments and other.......................................       924         645
                                                              --------    --------
          Total current assets..............................    40,612      45,856
Natural gas and oil properties, full cost method
  Unevaluated properties....................................    60,258     104,075
  Properties subject to amortization........................   468,062     566,868
Other property and equipment................................     7,308       9,341
                                                              --------    --------
                                                               535,628     680,284
Less: Accumulated depreciation, depletion and
  amortization..............................................  (176,504)   (236,546)
                                                              --------    --------
                                                               359,124     443,738
Other assets................................................     1,549       1,797
                                                              --------    --------
          TOTAL ASSETS......................................  $401,285    $491,391
                                                              ========    ========
LIABILITIES:
Accounts payable and accrued expenses.......................  $ 36,650    $ 42,432
Accounts payable -- Brooklyn Union..........................     1,010          --
Deferred stock obligation...................................        --       8,825
                                                              --------    --------
          Total current liabilities.........................    37,660      51,257
Long-term debt..............................................    65,000     113,000
Deferred federal income taxes...............................    56,475      70,741
Other deferred liabilities..................................     8,850         206
                                                              --------    --------
          TOTAL LIABILITIES.................................   167,985     235,204
COMMITMENTS AND CONTINGENCIES (SEE NOTE 10)
STOCKHOLDERS' EQUITY:
  Common Stock, $.01 par value, 50,000 shares authorized and
     23,333
     shares issued and outstanding at December 31, 1996 and
      23,361
     shares issued and outstanding at December 31, 1997.....       233         234
  Additional paid-in capital................................   222,271     221,907
  Retained earnings.........................................    10,796      34,046
                                                              --------    --------
          TOTAL STOCKHOLDERS' EQUITY........................   233,300     256,187
                                                              --------    --------
          TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY........  $401,285    $491,391
                                                              ========    ========
</TABLE>
 
    The accompanying notes are an integral part of these combined financial
                                  statements.
                                       F-3
<PAGE>   110
 
                        THE HOUSTON EXPLORATION COMPANY
 
                       COMBINED STATEMENTS OF OPERATIONS
 
<TABLE>
<CAPTION>
                                                                     YEARS ENDED DECEMBER 31,
                                                              ---------------------------------------
                                                                 1995          1996          1997
                                                              ----------    ----------    -----------
                                                               (IN THOUSANDS, EXCEPT PER SHARE DATA)
<S>                                                           <C>           <C>           <C>
REVENUES:
  Natural gas and oil revenues..............................   $39,431       $64,864       $116,349
  Other.....................................................     1,778         1,040          1,297
                                                               -------       -------       --------
          Total revenues....................................    41,209        65,904        117,646
OPERATING COSTS AND EXPENSES:
  Lease operating...........................................     5,005        10,800         14,146
  Severance tax.............................................       463         1,401          4,233
  Depreciation, depletion and amortization..................    21,969        33,732         59,081
  General and administrative, net...........................     3,486         6,249          5,825
  Nonrecurring charge.......................................    12,000            --             --
                                                               -------       -------       --------
          Total operating expenses..........................    42,923        52,182         83,285
INCOME (LOSS) FROM OPERATIONS...............................    (1,714)       13,722         34,361
Interest expense, net.......................................     2,398         2,875            938
                                                               -------       -------       --------
Net income (loss) before income taxes.......................    (4,112)       10,847         33,423
Provision (benefit) for federal income taxes................    (3,809)        2,205         10,173
                                                               -------       -------       --------
NET INCOME (LOSS)...........................................   $  (303)      $ 8,642       $ 23,250
                                                               =======       =======       ========
Net income (loss) per share.................................   $ (0.02)      $  0.49       $   1.00
                                                               =======       =======       ========
Net income (loss) per share -- assuming dilution............   $ (0.02)      $  0.49       $   0.97
                                                               =======       =======       ========
Weighted average shares outstanding.........................    15,295        17,532         23,337
</TABLE>
 
    The accompanying notes are an integral part of these combined financial
                                  statements.
                                       F-4
<PAGE>   111
 
                        THE HOUSTON EXPLORATION COMPANY
 
                   COMBINED STATEMENT OF STOCKHOLDERS' EQUITY
 
<TABLE>
<CAPTION>
                                                              ADDITIONAL                  TOTAL
                                                     COMMON    PAID IN     RETAINED   STOCKHOLDERS'
                                                     STOCK     CAPITAL     EARNINGS      EQUITY
                                                     ------   ----------   --------   -------------
                                                                     (IN THOUSANDS)
<S>                                                  <C>      <C>          <C>        <C>
Balance at December 31, 1994.......................   $153     $ 86,256    $ 2,457      $ 88,866
  Capital contributions from Brooklyn Union(1).....     --       14,673         --        14,673
  Net loss.........................................     --           --       (303)         (303)
                                                      ----     --------    -------      --------
Balance at December 31, 1995.......................   $153     $100,929    $ 2,154      $103,236
  Capital contributions from Brooklyn Union........     --        6,342         --         6,342
  8,037 shares of common stock at $15.50(2)........     80      115,000         --       115,080
  Net income.......................................     --           --      8,642         8,642
                                                      ----     --------    -------      --------
Balance at December 31, 1996.......................   $233     $222,271    $10,796      $233,300
  Other(3).........................................     --         (660)        --          (660)
  28 shares of common stock at $15.50(4)...........      1          296         --           297
  Net income.......................................     --           --     23,250        23,250
                                                      ----     --------    -------      --------
Balance at December 31, 1997.......................   $234     $221,907    $34,046      $256,187
                                                      ====     ========    =======      ========
</TABLE>
 
- ---------------
 
(1) Includes $7.8 million related to the $12.0 million nonrecurring charge, net
    of the tax benefit of $4.2 million.
 
(2) See Note 3 -- Stockholders' Equity.
 
(3) Non-cash charge relating to the February 1996 Reorganization.
 
(4) See Note 4 -- Incentive Stock Option Plan.
 
    The accompanying notes are an integral part of these combined financial
                                  statements.
                                       F-5
<PAGE>   112
 
                        THE HOUSTON EXPLORATION COMPANY
 
                       COMBINED STATEMENTS OF CASH FLOWS
 
<TABLE>
<CAPTION>
                                                               YEARS ENDED DECEMBER 31,
                                                          -----------------------------------
                                                            1995         1996         1997
                                                          ---------    ---------    ---------
                                                                    (IN THOUSANDS)
<S>                                                       <C>          <C>          <C>
OPERATING ACTIVITIES:
Net income (loss).......................................  $    (303)   $   8,642    $  23,250
Adjustments to reconcile net income (loss) to net cash
  provided by operating activities:
  Depreciation, depletion and amortization..............     21,969       33,732       59,081
  Deferred income tax expense...........................      9,632       11,939       13,601
  Nonrecurring charge...................................     12,000           --           --
  Changes in operating assets and liabilities:
     Decrease (increase) in accounts receivable.........        977      (10,348)      (3,356)
     Decrease (increase) in inventories.................        333          217         (273)
     Decrease (increase) in prepayments and other.......        416          (29)         279
     Decrease (increase) in other assets and
       liabilities......................................        864          909          (62)
     Increase in accounts payable and accrued
       expenses.........................................      9,890        9,003        4,772
                                                          ---------    ---------    ---------
Net cash provided by operating activities...............     55,778       54,065       97,292
INVESTING ACTIVITIES:
Investment in property and equipment....................    (70,249)    (154,125)    (145,055)
Dispositions and other..................................      1,316        1,819        1,360
                                                          ---------    ---------    ---------
Net cash used in investing activities...................    (68,933)    (152,306)    (143,695)
FINANCING ACTIVITIES:
Proceeds from long term borrowings......................      6,212       76,838       79,000
Repayments of long term borrowings......................         --      (83,700)     (31,000)
Proceeds from issuance of common stock, net of offering
  costs.................................................         --      101,014          297
Capital contributions from Brooklyn Union...............      6,873        6,342           --
                                                          ---------    ---------    ---------
Net cash provided by financing activities...............     13,085      100,494       48,297
Increase (decrease) in cash and cash equivalents........        (70)       2,253        1,894
Cash and cash equivalents, beginning of period..........        668          598        2,851
                                                          ---------    ---------    ---------
Cash and cash equivalents, end of period................  $     598    $   2,851    $   4,745
                                                          =========    =========    =========
Cash paid for interest..................................  $   4,658    $   5,708    $   6,001
                                                          =========    =========    =========
Cash paid for taxes.....................................  $      --    $      --    $      --
                                                          =========    =========    =========
</TABLE>
 
    The accompanying notes are an integral part of these combined financial
                                  statements.
                                       F-6
<PAGE>   113
 
                        THE HOUSTON EXPLORATION COMPANY
 
                     NOTES TO COMBINED FINANCIAL STATEMENTS
 
NOTE 1 -- SUMMARY OF ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES
 
  Organization
 
     The Houston Exploration Company ("Houston Exploration" or the "Company"), a
Delaware corporation, was incorporated in December 1985 and began operations in
January 1986 for the purpose of conducting certain natural gas and oil
exploration and development activities for The Brooklyn Union Gas Company
("Brooklyn Union"). Effective September 29, 1997, Brooklyn Union became a
wholly-owned subsidiary of KeySpan Energy Corporation, ("KeySpan"). Prior to the
Company's initial public offering in September 1996 (the "IPO"), the Company was
an indirect wholly-owned subsidiary of Brooklyn Union. Subsequent to the IPO,
Brooklyn Union holds 65% of the Company's outstanding common stock. The
Company's operations focus on the exploration, development and acquisition of
domestic natural gas and oil properties offshore in the Gulf of Mexico and
onshore in South Texas, the Arkoma Basin, East Texas and West Virginia.
 
     Effective February 29, 1996 Brooklyn Union implemented a reorganization of
its exploration and production assets and liabilities by transferring to Houston
Exploration certain onshore producing properties and acreage formerly owned by
Fuel Resources Inc. ("FRI"), another subsidiary of Brooklyn Union. These
combined financial statements have been prepared giving effect to the transfer
of these assets and liabilities from the time of the acquisition of such assets
and liabilities by Brooklyn Union. The transfer of assets and liabilities has
been accounted for at historical cost as a reorganization of companies under
common control in a manner similar to a pooling-of-interests and the 1995
financial statements reflect the combined historical results of Houston
Exploration and the assets and liabilities transferred by Brooklyn Union.
 
  Net Income (Loss) Per Share
 
     In February 1997, the Financial Accounting Standards Board (the "FASB")
issued Statement of Financial Accounting Standards ("SFAS") No. 128, "Earnings
Per Share." The statement specifies the computation, presentation, and
disclosure requirements for earnings per share ("EPS") and is designed to
improve the EPS information provided in the financial statements by simplifying
the existing computation. Primary EPS has been replaced with Basic EPS which is
calculated by dividing net income by the weighted average number of shares of
common stock outstanding during the year. No dilution for any potentially
dilutive securities is included. Fully diluted EPS is now called Diluted EPS and
assumes the conversion of all potentially dilutive securities. The Company
adopted SFAS No. 128 in its December 31, 1997 financial statements and has
presented Diluted EPS for the years 1996 and 1995 which were previously not
required as the dilutive effect of options and contingent shares was less than
3%. As of December 31, 1997, the Company had 2,333,276 options authorized, of
which 1,640,098 were outstanding, and had an estimated 521,509 contingent shares
of common stock payable to Soxco pursuant to the accrued minimum purchase price
of $8.8 million (see Note 12 -- Acquisitions).
 
                                       F-7
<PAGE>   114
                        THE HOUSTON EXPLORATION COMPANY
 
             NOTES TO COMBINED FINANCIAL STATEMENTS -- (CONTINUED)
 
     Under the requirements of SFAS No. 128, the Company's EPS are as follows:
 
<TABLE>
<CAPTION>
                                                                  1995          1996          1997
                                                               ----------    ----------    ----------
                                                               (IN THOUSANDS, EXCEPT PER SHARE DATA)
<S>                                                            <C>           <C>           <C>
Net income (loss)...........................................    $  (303)      $ 8,642       $23,250
Denominator:
Weighted average shares outstanding.........................     15,295        17,532        23,337
Add: dilutive securities
  Options...................................................         --            27           153
  Contingent shares.........................................         --           128           538
                                                                -------       -------       -------
Total weighted average shares outstanding and dilutive
  securities................................................     15,295        17,687        24,028
                                                                =======       =======       =======
Net income (loss) per share.................................    $ (0.02)      $  0.49       $  1.00
Net income (loss) per share -- assuming dilution............    $ (0.02)      $  0.49       $  0.97
</TABLE>
 
  Reclassifications and Use of Estimates
 
     The preparation of the combined financial statements in conformity with
generally accepted accounting principles requires management to make estimates
and assumptions that affect the reported amounts of assets and liabilities and
disclosure of contingent assets and liabilities at the dates of the financial
statements and the reported amounts of revenues and expenses during the
reporting periods. The Company's most significant financial estimates are based
on remaining proved natural gas and oil reserves. See Note 13 -- Supplemental
Information on Natural Gas and Oil Exploration, Development and Production
Activities. Because there are numerous uncertainties inherent in the estimation
process, actual results could differ from the estimates. Certain
reclassifications for prior years have been made to conform with current year
presentation.
 
  Natural Gas and Oil Properties
 
     Natural gas and oil properties are accounted for using the full cost method
of accounting. Under this method of accounting, all costs identified with
acquisition, exploration and development of natural gas and oil properties,
including leasehold acquisition costs, geological and geophysical costs, dry
hole costs, tangible and intangible drilling costs, interest and the general and
administrative overhead directly associated with these activities are
capitalized as incurred. The Company computes the provision for depreciation,
depletion and amortization of natural gas and oil properties on a quarterly
basis using the unit-of-production method. The quarterly provision is calculated
by multiplying the natural gas and oil production each quarter by a depletion
rate determined by dividing the total unamortized cost of natural gas and oil
properties (including estimates of the costs of future development and property
abandonment and excluding the cost of significant investments in unproved and
unevaluated properties) by net equivalent proved reserves at the beginning of
the quarter. Natural gas and oil reserve quantities represent estimates only.
Actual future production may be materially different from estimated reserve
quantities and such differences could materially affect future amortization of
natural gas and oil properties. The Company believes that unevaluated properties
at December 31, 1997 will be fully evaluated within five years.
 
     Proceeds from the dispositions of natural gas and oil properties are
recorded as reductions of capitalized costs, with no gain or loss recognized,
unless such adjustments significantly alter the relationship of unamortized
capitalized costs and total proved reserves.
 
     The Company limits the capitalized costs of natural gas and oil properties,
net of accumulated depreciation, depletion and amortization and related deferred
taxes to the estimated future net cash flows from proved natural gas and oil
reserves discounted at ten percent, plus the lower of cost or fair value of
unproved properties, as adjusted for related income tax effects (the "full cost
ceiling"). A current period charge to operating income is required to the extent
that capitalized costs plus certain estimated costs for future property
                                       F-8
<PAGE>   115
                        THE HOUSTON EXPLORATION COMPANY
 
             NOTES TO COMBINED FINANCIAL STATEMENTS -- (CONTINUED)
 
development, plugging, abandonment and site restorations, net of related
accumulated depreciation, depletion and amortization and related deferred income
taxes, exceed the full cost ceiling.
 
  Other Property and Equipment
 
     Other property and equipment include the costs of West Virginia gathering
facilities which are depreciated using the unit-of-production basis utilizing
estimated proved reserves accessible to the facilities. Also included in other
property and equipment are costs of office furniture, fixtures and equipment
which are recorded at cost and depreciated using the straight-line method over
estimated useful lives ranging between two to five years.
 
  Income Taxes
 
     Deferred taxes are determined based on the estimated future tax effect of
differences between the financial statement and tax basis of assets and
liabilities given the provisions of enacted tax laws. These differences relate
primarily to (i) intangible drilling and development costs associated with
natural gas and oil properties, which are capitalized and amortized for
financial reporting purposes and expensed as incurred for tax reporting purposes
and (ii) provisions for depreciation and amortization for financial reporting
purposes that differ from those used for income tax reporting purposes.
 
     Prior to September 30, 1996, the Company was included in the consolidated
federal income tax return of Brooklyn Union. Under the Company's tax sharing
agreement with Brooklyn Union, the Company received or paid to Brooklyn Union an
amount equal to the reduction or increase in the currently payable federal
income taxes for Brooklyn Union resulting from the inclusion of the Company's
taxable income or loss in the consolidated Brooklyn Union return, whether or not
such amounts could be utilized on a separate return basis. For periods
subsequent to September 1996, the Company is no longer included in the
consolidated federal income tax return of Brooklyn Union and therefore
calculates taxes on a separate return basis.
 
  Cash and Cash Equivalents
 
     The Company considers all highly liquid investments with an original
maturity of three months or less to be cash equivalents.
 
  Inventories
 
     Inventories consist primarily of tubular goods used in the Company's
operations and are stated at the lower of cost or market value.
 
  General and Administrative Costs and Expenses
 
     The Company receives reimbursement for administrative and overhead expenses
incurred on behalf of other working interest owners of properties operated by
the Company. These reimbursements totaling $1.2 million, $1.0 million and $0.9
million for the years ended December 31, 1995, 1996 and 1997, respectively, were
allocated as reductions to general and administrative expenses. The capitalized
general and administrative costs directly related to the Company's acquisition,
exploration and development activities, during 1995, 1996 and 1997, aggregated
$4.1 million, $5.3 million and $7.2 million, respectively.
 
  Capitalization of Interest
 
     The Company capitalizes interest related to its unevaluated natural gas and
oil properties and certain properties under development which are not currently
being amortized. For the years ended December 31, 1995, 1996 and 1997 interest
costs of $2.9 million, $3.5 million and $5.9 million, respectively, were
capitalized.
 
                                       F-9
<PAGE>   116
                        THE HOUSTON EXPLORATION COMPANY
 
             NOTES TO COMBINED FINANCIAL STATEMENTS -- (CONTINUED)
 
  Gas Imbalances
 
     The Company utilizes the entitlements method to account for its gas
imbalances. Under this method, income is recorded based on the Company's net
revenue interest in production or nominated deliveries. Net deliveries in excess
of these amounts are recorded as liabilities, while net under deliveries are
reflected as assets. Production imbalances are valued using current market
prices. Production imbalances were not material as of December 31, 1996 and
1997.
 
  Hedging
 
     The Company utilizes derivative commodity instruments to hedge future sales
prices on a portion of its natural gas production in order to achieve a more
predictable cash flow and to reduce its exposure to adverse price fluctuations.
These instruments include swaps, costless collars and options, and are usually
placed with major financial institutions that the Company believes are minimal
credit risks. The Company's hedging strategies meet the criteria for hedge
accounting treatment under Statement of Financial Accounting Standards No. 80,
"Accounting for Futures Contracts" ("SFAS 80"). Accordingly, gains and losses
are recognized when the underlying transaction is completed, at which time these
gains and losses are included in earnings as a component of natural gas revenues
in accordance with a hedged transaction. Natural gas revenues were increased by
$5.6 million in 1995, and were reduced by $11.1 million and $9.9 million during
1996 and 1997, relative to these contracts. See Note 8 -- Financial Instruments.
 
     The Company regularly assesses the relationship between natural gas
commodity prices in the "cash" and futures markets. The correlation between
prices in these markets has been well within a range generally deemed to be
acceptable. If correlation ceases to exist for more than a temporary period of
time, the Company accounts for its financial instrument positions as trading
activities and marks-to-market its open positions.
 
     The Company also uses interest rate swaps to manage the interest rate
exposure arising from certain borrowings. Swaps used to hedge debt are
designated as hedges and are matched to the debt as to notional amount and
maturity. The periodic receipts or payments from each swap are recognized
ratably over the term of the swap as an adjustment to interest expense. Gains
and losses resulting from the termination of hedge contracts prior to their
stated maturity are recognized ratably over the remaining life of the instrument
being hedged.
 
  Concentration of Credit Risk
 
     Substantially all of the Company's accounts receivable result from natural
gas and oil sales or joint interest billings to third parties in the oil and gas
industry. This concentration of customers and joint interest owners may impact
the Company's overall credit risk in that these entities may be similarly
affected by changes in economic and other conditions. Historically the Company
has not experienced credit losses on such receivables.
 
  New Accounting Pronouncements
 
     In October 1995, the FASB issued SFAS No. 123, "Accounting for Stock-Based
Compensation," which is effective for years beginning after December 15, 1995.
This statement encourages, but does not require companies to record compensation
expense for stock-based compensation at fair value. The Company has chosen to
continue to account for stock-based compensation using the intrinsic value
method prescribed in Accounting Principles Board Opinion ("APB") No. 25,
"Accounting for Stock Issued to Employees," and related Interpretations. Under
APB No. 25, compensation expense is measured as the excess, if any, of the fair
market value of the Company's stock at the date of grant over the price at which
the option was granted. Compensation expense for phantom stock rights is
recorded annually based on the quoted market price of the Company's stock at the
end of the period. See Note 4 -- Incentive Stock Option Plans.
 
                                      F-10
<PAGE>   117
                        THE HOUSTON EXPLORATION COMPANY
 
             NOTES TO COMBINED FINANCIAL STATEMENTS -- (CONTINUED)
 
     In February 1997, the FASB issued SFAS No. 129, "Disclosure of Information
About Capital Structure," which consolidates the existing requirements to
disclose certain information about an entity's capital structure, for both
public and nonpublic entities. In June 1997, the FASB issued SFAS No. 130,
"Reporting Comprehensive Income," which establishes standards for reporting and
display of comprehensive income and its components. Also issued in June of 1997
was SFAS No. 131, "Disclosures About Segments of an Enterprise and Related
Information," which specifies and revises guidelines for determining an entity's
operating and geographic segments and the type and level of financial
information about those segments to be disclosed. The Company has adopted the
provisions of SFAS Nos. 129, 130 and 131 in its 1997 financial statements. The
adoption of SFAS Nos. 129, 130 and 131 did not have an effect on results of
operations or the calculation of net income.
 
NOTE 2 -- LONG-TERM DEBT
 
     Credit Facility. On July 2, 1996, the Company entered into a revolving
credit facility ("Credit Facility") with a syndicate of lenders led by Chase
Bank of Texas, National Association ("Chase"), which provides an aggregate
commitment of $150 million, subject to borrowing base limitations, of which $130
million was the available borrowing base at December 31, 1997. In addition, up
to $5 million of the Credit Facility is available for the issuance of letters of
credit to support performance guarantees. The Credit Facility matures on July 1,
2000 and is unsecured. At December 31, 1997, $113 million was outstanding under
the Credit Facility and $1.6 million was outstanding in letter of credit
obligations.
 
     Interest is payable on borrowings under the Credit Facility, at the
Company's option, at an alternate base rate of the greater of the Federal Funds
rate plus 0.5% or Chase's prime rate or at a margin of 0.375% to 1.125% above a
quoted LIBOR rate. Interest is payable at calendar quarters on base rate loans
and at maturity on LIBOR loans. In addition, a commitment fee of: (i) between
0.20% and 0.375% per annum on the unused portion of the Designated Borrowing
Base, and (ii) 33% of the fee in (i) above on the difference between the lower
of the Facility Amount or the Borrowing Base and the Designated Borrowing Base.
The weighted average interest rate was 6.9%, 6.25% and 6.9%, respectively, for
the years ended December 31, 1995, 1996 and 1997.
 
     The Credit Facility, as amended, contains covenants of the Company,
including certain restrictions on liens and financial covenants which require
the Company to, among other things, maintain (i) an interest coverage ratio of
2.5 to 1.0 of earnings before interest, taxes and depreciation ("EBITDA") to
cash interest and (ii) a total debt to capitalization ratio of less than 60%. In
addition to maintenance of certain financial ratios, cash dividends and/or
purchase or redemption of the Company's stock is restricted as well as the
encumbering of the Company's gas and oil assets or the pledging of the assets as
collateral. As of December 31, 1997, the Company was in compliance with all such
covenants.
 
NOTE 3 -- STOCKHOLDERS' EQUITY
 
     On September 19, 1996, the Company entered into an underwriting agreement
with respect to the Company's IPO of its common stock at a price of $15.50 per
share. The initial closing of the IPO, in which the Company issued 6,200,000
shares of common stock, was completed on September 25, 1996. The underwriters
delivered notice of the exercise of their over-allotment option on September 30,
1996. The closing of the over-allotment, in which the Company issued an
additional 930,000 shares of common stock, was completed on October 3, 1996. The
Company received net proceeds of approximately $101.0 million from the total of
7,130,000 shares sold in the IPO.
 
     Concurrently with the completion of the IPO, the Company's President
exchanged certain of his after program-payout working interests valued at $2.3
million for 145,161 shares of common stock. In addition, concurrently with the
completion of the IPO, the Company issued 762,387 shares of common stock valued
at $11.8 million to Soxco in connection with the Soxco Acquisition. See Note
12 -- Acquisitions.
                                      F-11
<PAGE>   118
                        THE HOUSTON EXPLORATION COMPANY
 
             NOTES TO COMBINED FINANCIAL STATEMENTS -- (CONTINUED)
 
NOTE 4 -- INCENTIVE STOCK OPTION PLANS
 
  1994 Incentive Plan
 
     On July 1, 1994, the Company adopted the Long-Term Stock Incentive Plan
(the "1994 Incentive Plan"), and granted options to purchase 247,000 shares of
common stock at $11.22 per share to certain officers and directors of Brooklyn
Union. Options under the 1994 Incentive Plan were nonqualified and had tandem
phantom option shares that gave the option holder the right to receive a cash
payment five years from the grant date provided the Company was a privately held
entity. At completion of the Company's IPO on September 20, 1996, all options
under the 1994 Incentive Plan were canceled in exchange for a cash payment by
the Company of $840,000. The Company recorded the $840,000 charge as
compensation expense.
 
  1996 Incentive Plan
 
     At the completion of the IPO, the Company adopted the 1996 Stock Option
Plan (the "1996 Incentive Plan"), which allows the Company to grant options not
to exceed 10% of the shares of the Company's common stock outstanding from time
to time. On September 20, 1996, the Company authorized 2,333,276 options and
subsequently granted 1,697,238 options. The options granted under the 1996
Incentive Plan expire 10 years from the grant date and vest in one-fifth
increments on each of the first five anniversaries of the grant date. During
1997, employees of the Company exercised 28,140 options at a weighted average
price of $15.50. As of December 31, 1997, 266,188 options were vested and
exercisable. No options were exercisable at December 31, 1996.
 
     During 1997, the 1996 Incentive Plan was amended to allow option grants to
non-employee directors of the Company. Options granted to non-employee directors
vest on the date of grant. During 1997 the Company granted 49,000 options to
non-employee directors at a grant price of $20.813.
 
     Under the 1996 Incentive Plan, 1,048,770 of the options granted are
incentive stock options ("ISOs") and the balance, 648,468 are nonqualified stock
options ("NQSOs"). Common stock issued through the exercise of nonqualified
options will result in a tax deduction for the Company equivalent to the taxable
gain recognized by the optionee. Generally, the Company will not receive an
income tax deduction for ISOs.
 
     The following is a summary of option activity during the years ended
December 31, 1995, 1996 and 1997:
 
<TABLE>
<CAPTION>
                                                    YEARS ENDED DECEMBER 31,
                                 ---------------------------------------------------------------
                                       1995                  1996                   1997
                                 -----------------    -------------------    -------------------
                                 SHARES     PRICE*     SHARES      PRICE*     SHARES      PRICE*
<S>                              <C>        <C>       <C>          <C>       <C>          <C>
Options at beginning of
  year.......................    247,000    $11.22      247,000    $11.22    1,239,638    $15.53
  Granted....................         --              1,239,638     15.53      457,600     19.68
  Exercised..................         --                     --                (28,140)    15.50
  Forfeited..................         --                     --                (29,000)    15.50
  Canceled...................         --               (247,000)    11.22           --
                                 -------              ---------              ---------
Outstanding at end of year...    247,000    $11.22    1,239,638    $15.53    1,640,098    $16.69
                                 -------              ---------              ---------
Exercisable at end of year...    247,000    $11.22           --                266,188
Options available for
  grant......................         --              1,093,638                665,038
Weighted average fair value
  of options granted.........                         $    7.17              $    7.60
</TABLE>
 
- ---------------
 
* Weighted average exercise price for the year.
 
                                      F-12
<PAGE>   119
                        THE HOUSTON EXPLORATION COMPANY
 
             NOTES TO COMBINED FINANCIAL STATEMENTS -- (CONTINUED)
 
  Phantom Stock Rights
 
     On December 16, 1996, the Company granted key employees of Houston
Exploration 176,470 phantom stock rights ("PSRs") that give the holder the right
to receive a cash payment determined by reference to the fair market value of
one share of the Company's common stock. Twenty percent (20%) of the PSRs are
payable on December 16th of each of the years 1997 through 2001. On each date on
which a PSR is payable, the holder will receive a cash payment equal to (i) the
average of the closing prices per share of the Company's common stock for the
five trading days immediately preceding such payment date multiplied by (ii) the
number of PSRs payable on such date. During 1997, the Company made payments of
$0.8 million for the vested portion of PSRs.
 
     Effective October 1, 1997, the Company adopted an incentive compensation
plan for non-employee, non-affiliated directors under which they may defer
current compensation in the form of phantom stock rights that are tied to the
market price of the Common Stock on the date services are performed. Phantom
stock rights are exchanged for a cash distribution upon retirement.
 
  Fair Value of Employee Stock-Based Compensation
 
     The Company accounts for the Incentive Stock Plans using the intrinsic
value method prescribed under APB No. 25 and accordingly no compensation expense
has been recognized for stock options granted. Had stock options been accounted
for using the fair value method as recommended in SFAS No. 123, compensation
expense would have had the following pro forma effect on the Company's net
income and earnings per share for the years ended December 31, 1995, 1996 and
1997:
 
<TABLE>
<CAPTION>
                                                        1995          1996          1997
                                                      --------      --------      ---------
                                                      (IN THOUSANDS, EXCEPT PER SHARE DATA)
<S>                                                   <C>           <C>           <C>
Net income (loss) -- as reported....................   $ (303)       $8,642        $23,250
Net income (loss) -- pro forma......................     (303)        8,268         21,499
Net income (loss) per share -- as reported..........   $(0.02)       $ 0.49        $  1.00
Net income (loss) per share -- pro forma............    (0.02)         0.47           0.92
Net income (loss) per share -- pro forma -- assuming
  dilution..........................................    (0.02)         0.47           0.89
</TABLE>
 
     The effects of applying SFAS No. 123 in this pro forma disclosure are not
indicative of future amounts. SFAS No. 123 does not apply to awards prior to
1995. The fair value of each option grant is estimated on the date of grant
using the Black-Scholes option pricing model with the following assumptions used
for grants in 1996 and 1997: (i) risk-free interest rate of 6.66% in 1996 and
6.30% in 1997; (ii) expected lives of 5 years; (iii) expected dividends of zero;
and (iv) expected volatility of 41%.
 
NOTE 5 -- INCOME TAXES
 
     The components of the federal income tax provision (benefit) are:
 
<TABLE>
<CAPTION>
                                                         1995       1996       1997
                                                       --------    -------    -------
                                                               (IN THOUSANDS)
<S>                                                    <C>         <C>        <C>
Current..............................................  $(13,441)   $(9,734)   $(3,428)
Deferred.............................................     9,632     11,939     13,601
                                                       --------    -------    -------
          Total......................................  $ (3,809)   $ 2,205    $10,173
                                                       ========    =======    =======
</TABLE>
 
     The credit in the current provision for 1997 includes (i) proceeds of $1.2
million received in connection with the sale of Section 29 tax credits to
Brooklyn Union during the first quarter of 1997 (see Note 6 --
 
                                      F-13
<PAGE>   120
                        THE HOUSTON EXPLORATION COMPANY
 
             NOTES TO COMBINED FINANCIAL STATEMENTS -- (CONTINUED)
 
Related Party Transactions) and (ii) an adjustment to the 1996 tax return.
Amounts received from Brooklyn Union pursuant to the previous tax-sharing
agreement were $14.6 million and $13.7 million in 1995 and 1996, respectively.
No amounts were received in 1997, as effective September 30, 1996, the Company
became a stand alone tax entity and is no longer consolidated with Brooklyn
Union.
 
     The following is a reconciliation of statutory federal income tax expense
(benefit) to the Company's income tax provision:
 
<TABLE>
<CAPTION>
                                                         1995       1996       1997
                                                        -------    -------    -------
                                                               (IN THOUSANDS)
<S>                                                     <C>        <C>        <C>
Income (loss) before income taxes.....................  $(4,112)   $10,847    $33,423
Statutory rate........................................       35%        35%        35%
Income tax expense (benefit) computed at statutory
  rate................................................   (1,439)     3,796     11,698
Reconciling items:
     Section 29 tax credits...........................   (1,985)    (1,401)    (1,200)
     Percentage depletion.............................     (231)       (33)       (14)
     Other............................................     (154)      (157)      (311)
                                                        -------    -------    -------
Tax expense (benefit).................................  $(3,809)   $ 2,205    $10,173
                                                        =======    =======    =======
</TABLE>
 
  Deferred Income Taxes
 
     The components of deferred tax assets and liabilities pursuant to SFAS No.
109 for the years ended December 31, 1996 and 1997 primarily represent temporary
differences related to natural gas and oil properties.
 
NOTE 6 -- RELATED PARTY TRANSACTIONS
 
  Sale of Section 29 Tax Credits
 
     Effective January 1, 1997, the Company entered into an agreement to sell to
a subsidiary of Brooklyn Union certain interests in onshore producing wells of
the Company that produce from formations that qualify for tax credits under
Section 29 of the Internal Revenue Code ("Section 29"). Section 29 provides for
a tax credit from non-conventional fuel sources such as oil produced from shale
and tar sands and natural gas produced from geopressured brine, Devonian shale,
coal seams and tight sands formations. Brooklyn Union acquired an economic
interest in wells that are qualified for the tax credits and in exchange, the
Company (i) retained a volumetric production payment and a net profits interest
of 100% in the properties, (ii) received a cash down payment of $1.4 million and
(iii) will receive a quarterly payment of $0.75 for every dollar of tax credit
utilized. The Company will manage and administer the daily operations of the
properties in exchange for an annual management fee of $100,000. At December 31,
1997, the balance sheet effect of this transaction was a $1.4 million reduction
to the full cost pool for the down payment. The income statement effect for the
year ended December 31, 1997 was a reduction to income tax expense of $1.2
million, representing benefits received from the Section 29 tax credits.
 
  General and Administrative Expense
 
     The Company reimburses Brooklyn Union for certain general and
administrative costs. During the years ended December 31, 1995, 1996 and 1997,
the Company paid Brooklyn Union $0.7 million, $0.6 million and $0.1 million in
general and administrative reimbursements.
 
                                      F-14
<PAGE>   121
                        THE HOUSTON EXPLORATION COMPANY
 
             NOTES TO COMBINED FINANCIAL STATEMENTS -- (CONTINUED)
 
  Gas Sales
 
     In 1992, the Company entered into a term supply agreement with BRING Gas
Services Corp. ("BRING"), an affiliate of Brooklyn Union, at that time. As of
April 1, 1995, this contract was superseded when the Company entered into a term
supply agreement with PennUnion Energy Services, L.L.C. ("PennUnion"), successor
to BRING, and an affiliate of Brooklyn Union. This contract was terminated in
October 1996 with Brooklyn Union's sale of its interest in PennUnion. Under the
terms of the agreement, the Company agreed to sell and PennUnion agreed to buy a
substantial portion of the Company's production at index-related prices. The
agreement contained provisions for both the commitment of gas reserves
subsequently developed or acquired by the Company and the release of gas
reserves sold, traded or exchanged to third parties.
 
     For the years ended December 31, 1995 and 1996 the Company had natural gas
sales of $18.9 million and $26.7 million, respectively, to PennUnion.
 
  Employment Contracts
 
     Prior to the IPO the Company maintained an employment agreement with its
President and Chief Executive Officer which provided him with the option to
participate in up to a 5% working interest in certain prospects of the Company.
During 1995 and 1996, affiliates of the Company's President obtained a 5%
working interest in 144 wells (which includes 142 Charco wells) operated by the
Company pursuant to such agreement. In addition, during 1995, 1996 and 1997,
affiliates of the Company's President paid $0.7 million, $1.4 million and $3.3
million, respectively, in expenses attributable to working interests owned in
properties operated by the Company, and received $0.9 million, $1.6 million and
$3.9 million, respectively, in distributions attributable to such working
interests. See Note 12 -- Acquisitions.
 
     The employment agreement also provided for the assignment to the President
of a 2% net profits interest in all prospects of the Company and a 6.75% after
program-payout working interest. In addition, the employment agreement provided
for the assignment to certain key employees designated by the President of an
overriding royalty interest equivalent in the aggregate to a four percent net
revenue interest in certain properties acquired by the Company. Assignments were
made in two wells during 1995; no assignments were made in 1996 or 1997. Upon
completion of the IPO, the President's employment agreement was terminated and
replaced with a new employment agreement, which does not provide the President
with the option to participate in prospects of the Company or to receive or
grant assignments or after program-payout working interests. In addition to the
Company's President, certain other key employees of the Company entered into
employment agreements upon completion of the IPO.
 
NOTE 7 -- EMPLOYEE BENEFIT PLANS
 
  401(k) Profit Sharing Plan
 
     The Company maintains a 401(k) Profit Sharing Plan (the "401(k) Plan") for
its employees. Under the 401(k) Plan, eligible employees may elect to have the
Company contribute on their behalf up to 10% of their base compensation (subject
to certain limitations imposed under the Internal Revenue Code of 1986, as
amended) on a before tax basis. The Company makes a matching contribution of
$0.50 for each $1.00 of employee deferral, not to exceed 5% of an employee's
base compensation, subject to limitations imposed by the Internal Revenue
Service. The amounts contributed under the 401(k) Plan are held in a trust and
invested among various investment funds in accordance with the directions of
each participant. An employee's salary deferral contributions under the 401(k)
Plan are 100% vested. The Company's matching contributions vest at the rate of
20% per year of service. Participants are entitled to payment of their vested
account balances upon termination of employment. For the years ended December
31, 1995, 1996 and 1997, Company contributions to the 401(k) Plan were $157,000,
$158,000 and $210,000, respectively.
 
                                      F-15
<PAGE>   122
                        THE HOUSTON EXPLORATION COMPANY
 
             NOTES TO COMBINED FINANCIAL STATEMENTS -- (CONTINUED)
 
  Supplemental Executive Plan
 
     Effective immediately prior to the IPO, the Company adopted an unfunded,
nonqualified Supplemental Executive Retirement Plan (the "SERP") for the benefit
of James G. Floyd, the Company's President and Chief Executive Officer. The SERP
provides that, if the executive remains with the Company until age 65, upon his
retirement on or after age 65, the executive will be paid $100,000 per year for
life. If, after retirement, the executive predeceases his spouse, 50% of the
executive's SERP benefit will continue to be paid to the executive's surviving
spouse for her life. During 1997 the Company accrued $123,000 related to the
SERP and in 1996 no amounts were accrued as required accruals were de minimus.
 
NOTE 8 -- FINANCIAL INSTRUMENTS
 
<TABLE>
<CAPTION>
                                                                     DECEMBER 31,
                                                   ------------------------------------------------
                                                            1996                      1997
                                                   ----------------------    ----------------------
                                                   CARRYING    ESTIMATED     CARRYING    ESTIMATED
                                                    AMOUNT     FAIR VALUE     AMOUNT     FAIR VALUE
                                                   --------    ----------    --------    ----------
                                                                    (IN THOUSANDS)
<S>                                                <C>         <C>           <C>         <C>
Cash and cash equivalents........................  $ 2,851      $  2,851     $  4,745        4,745
Long-term debt...................................   65,000        65,000      113,000      113,000
Derivative transactions:
  Interest rate swap agreements:
     In a payable position.......................       --          (171)          --         (169)
Commodity price and basis swaps:
  In a payable position..........................       --       (30,286)          --         (516)
</TABLE>
 
  Cash and Cash Equivalents
 
     The carrying amount approximates fair value due to the short maturity of
these instruments.
 
  Long-Term Debt
 
     The carrying amount of borrowings outstanding under the Credit Facility
approximates fair value as the interest rate is tied to current market rates.
 
DERIVATIVE TRANSACTIONS
 
  Interest Rate Swap Agreements
 
     The fair values are obtained from the financial institutions that are
counterparties to the transactions. These values represent the estimated amount
the Company would pay or receive to terminate the agreements, taking into
consideration current interest rates and the current creditworthiness of the
counterparties. The Company's interest rate swap agreements are off balance
sheet transactions and, accordingly, no respective carrying amounts for these
transactions are included in the accompanying combined balance sheets at
December 31, 1997. At December 31, 1997, the Company had two interest rate swap
agreements to exchange an aggregate notional principal of $80.0 million over
various periods from November 1996 through November 1999 at rates between 5.805%
and 6.025%.
 
  Commodity Related Transactions
 
     The Company uses derivative financial instruments for non-trading purposes
as a hedging strategy to reduce the impact of market volatility and to ensure
cash flows. Gains and losses on these hedging transactions are recorded when the
related natural gas has been produced or delivered. While derivative financial
 
                                      F-16
<PAGE>   123
                        THE HOUSTON EXPLORATION COMPANY
 
             NOTES TO COMBINED FINANCIAL STATEMENTS -- (CONTINUED)
 
instruments are intended to reduce the Company's exposure to declines in the
market price of natural gas, the derivative financial instruments may limit the
Company's gain from increases in the market price.
 
     The derivative instruments used to hedge commodity transactions have
historically had high correlation with commodity prices and are expected to
continue to do so. The correlation of indices and prices is regularly evaluated
to ensure that the instruments continue to be effective hedges. In the event
that correlation falls below allowable levels, the gains or losses associated
with the hedging instruments are immediately recognized to the extent that
correlation was lost. In December of 1995, the Company recognized a pretax loss
of $0.7 million due to the loss of correlation of the New York Mercantile
Exchange ("NYMEX") futures market for natural gas with the market price for
natural gas in certain parts of the country. The Company's hedges in place at
December 31, 1996 or 1997 did not experience loss of market correlation.
 
  Commodity Price Swaps
 
     Price swap agreements call for one party to make monthly payments to (or
receive from) another party based upon the differential between a fixed and a
variable price (fixed-price swap) or two variable prices (basis swap) for a
notional volume specified by the contract. The fair value is the estimated
amount the Company would receive or pay to terminate swap agreements at
year-end, taking into account the difference between NYMEX natural gas prices or
index prices at year-end and fixed swap prices. NYMEX natural gas price closed
at $3.61 per MMbtu and $2.68 per MMbtu at December 31, 1996 and 1997,
respectively. At December 31, 1996 and 1997, the Company had fixed-price swap
agreements and basis swap agreements to exchange a total notional volume of
23,278 MMbtu and 5,410 MMbtu, respectively, of natural gas over the period
January 1996 through March 1998. The Company has no hedges in place past March
1998.
 
     The Company is exposed to credit risk in the event of nonperformance by
counterparties to futures and swaps contracts. The Company believes that the
credit risk related to the futures and swap contracts is no greater than that
associated with the primary contracts which they hedge, as these contracts are
with major investment grade financial institutions, and that elimination of the
price risk lowers the Company's overall business risk.
 
NOTE 9 -- SALES TO MAJOR CUSTOMERS
 
     As is the nature of the exploration, development and production business,
production is normally sold to relatively few customers. However, alternate
buyers are available to replace the loss of any of the Company's major
customers. For year ended December 31, 1995, PennUnion was the only customer for
which natural gas sales exceeded 10% of total revenues and during 1995 sales to
PennUnion comprised 46% of total revenues. For the year ended December 31, 1996,
the Company sold natural gas production representing more than 10% of its total
revenues to PennUnion (40%) and H&N Gas Ltd. (27%). For the year ended December
31, 1997, the Company's only customer to whom sales of natural gas production
represented more than 10% of its total revenues was H&N Gas Ltd. (38%). The
Company believes that prices at which it sold gas to PennUnion were similar to
those it would be able to obtain in the open market. The Company also believes
that the loss of H&N Gas Ltd. as a purchaser would not have a material adverse
effect on the Company's operations. See Note 6 -- Related Party Transactions.
 
NOTE 10 -- COMMITMENTS AND CONTINGENCIES
 
  Litigation
 
     The Company is involved from time to time in various claims and lawsuits
incidental to its business. In the opinion of management, the ultimate liability
thereunder, if any, will not have a material adverse effect on the financial
position or results of operations of the Company.
 
                                      F-17
<PAGE>   124
                        THE HOUSTON EXPLORATION COMPANY
 
             NOTES TO COMBINED FINANCIAL STATEMENTS -- (CONTINUED)
 
  Leases
 
     The Company has entered into certain noncancelable operating lease
agreements relative to office space and equipment with various expiration dates
through 2002. Minimum rental commitments under the terms of the leases are as
follows:
 
<TABLE>
<CAPTION>
                                                    MINIMUM                  NET MINIMUM
                                                    RENTAL       SUBLEASE      RENTAL
                                                  COMMITMENTS    RENTALS     COMMITMENTS
                                                  -----------    --------    -----------
                                                              (IN THOUSANDS)
<S>                                               <C>            <C>         <C>
1998............................................     $743         $(246)        $497
1999............................................      750          (250)         500
2000............................................      753          (252)         501
2001............................................      513           (84)         429
2002............................................      460            --          460
Thereafter......................................     $877         $  --         $877
</TABLE>
 
     Net rental expense related to these leases was $0.3 million for each of the
years ended December 31, 1997, 1996 and 1995.
 
NOTE 11 -- NONRECURRING CHARGE
 
     In connection with the February 1996 reorganization in which Brooklyn Union
transferred certain onshore producing properties and acreage to the Company,
certain former employees of FRI, the subsidiary of Brooklyn Union that
previously owned the onshore properties, were entitled to remuneration for the
increase in the value of the transferred properties prior to the reorganization.
The Company incurred a $12 million non-cash charge in the quarter ended December
31, 1995 with respect to the remuneration to which such employees of FRI were
entitled.
 
NOTE 12 -- ACQUISITIONS
 
  TransTexas
 
     On July 2, 1996, the Company acquired certain natural gas and oil
properties and associated gathering pipelines and equipment located in Zapata
County, Texas (the "TransTexas Acquisition") from TransTexas Gas Corporation and
TransTexas Transmission Corporation (together, "TransTexas"). The Company
acquired a 100% working interest (95% after the exercise by James G. Floyd, the
Company's President and Chief Executive Officer, of his right to purchase a 5%
working interest) in the approximately 142 wells on such properties. The
purchase price of $62.2 million ($59.1 million after giving effect to the
exercise of Mr. Floyd's purchase option) for the TransTexas Acquisition was
reduced by $3.1 million for production revenue and expenses related to the
assets between the May 1, 1996 effective date of the TransTexas Acquisition and
July 2, 1996. The purchase price of the TransTexas Acquisition was paid in cash,
financed with borrowings under the Company's Credit Facility.
 
     The Company loaned Mr. Floyd the $3.1 million purchase price for his
purchase of a 5% working interest in the properties purchased by the Company in
the TransTexas Acquisition. In addition, the Company has agreed to loan Mr.
Floyd, on a revolving basis, the amounts required to fund the expenses
attributable to Mr. Floyd's working interest. Mr. Floyd is required to repay
amounts owed under the loan in the amount of 65% of all distributions received
by Mr. Floyd in respect of such working interest, as distributions are received.
Amounts outstanding under such loan bear interest at an interest rate equal to
the Company's cost of borrowing under the Credit Facility. Mr. Floyd's
obligations under the agreement are secured by a pledge of his working interest
in, and the production from, such properties. As of December 31, 1997, the
outstanding balance owed by Mr. Floyd under the agreement was $3.7 million and
the loan will mature on July 2, 2006.
 
                                      F-18
<PAGE>   125
                        THE HOUSTON EXPLORATION COMPANY
 
             NOTES TO COMBINED FINANCIAL STATEMENTS -- (CONTINUED)
 
  Soxco
 
     On September 25, 1996, the Company acquired substantially all of the
natural gas and oil properties and related assets (the "Soxco Acquisition") of
Smith Offshore Exploration Company ("Soxco"). The natural gas and oil properties
acquired in the Soxco Acquisition consisted solely of working interests in
properties located in the Gulf of Mexico that are operated by the Company or in
which the Company also has a working interest. Pursuant to the Soxco
Acquisition, the Company paid Soxco cash in the aggregate amount of $20.3
million (net of $3.4 million for certain purchase price adjustments), and issued
to Soxco 762,387 shares of common stock with an aggregate value (determined by
reference to the IPO price) of $11.8 million. The cash portion of the purchase
price was funded with the proceeds of the IPO. In addition to the foregoing, the
Company will pay Soxco a deferred purchase price of up to $17.6 million
effective January 31, 1998. The amount of the deferred purchase price will be
determined by the probable reserves of Soxco as of December 31, 1995
(approximately 17.6 Bcfe) that are produced prior to or classified as proved as
of December 31, 1996 and December 31, 1997, respectively, provided that Soxco is
entitled to receive a minimum deferred purchase price of approximately $8.8
million. The amounts so determined will be paid in shares of common stock based
on the fair market value of such stock at the time of issuance. At December 31,
1997, the Company believes it is probable that only the minimum payment will be
required and as a result, $8.8 million has been accrued and reflected in current
liabilities.
 
  Pending Acquisition
 
     On January 12, 1998, the Company entered into a non-binding letter of
intent with respect to the acquisition of natural gas and oil properties located
onshore in South Louisiana, representing 45 Bcfe of net proved reserves (the
"South Louisiana Acquisition"). The average net production in December 1997
attributable to such properties was approximately 14 Mmcfe per day, net to the
Company's interest. The non-binding letter of intent provides for the Company to
pay $60 million for the properties to be acquired. The estimated purchase price
of $60 million is less than 10% of the Company's total assets and income
generated from these properties for the year ended December 31, 1997 was
estimated to be less than 20% of the Company's income from operations.
 
NOTE 13 -- SUPPLEMENTAL INFORMATION ON NATURAL GAS AND OIL EXPLORATION,
           DEVELOPMENT AND PRODUCTION ACTIVITIES
 
     The following information concerning the Company's natural gas and oil
operations has been provided pursuant to Statement of Financial Accounting
Standards No. 69, "Disclosures about Oil and Gas Producing Activities." The
Company's natural gas and oil producing activities are conducted onshore within
the continental United States and offshore in federal and state waters of the
Gulf of Mexico. The Company's natural gas and oil reserves were estimated by
independent reserve engineers.
 
  Capitalized Costs of Natural Gas and Oil Properties
 
     As of December 31, 1995, 1996 and 1997, the Company's capitalized costs of
natural gas and oil properties are as follows:
 
<TABLE>
<CAPTION>
                                                       1995        1996        1997
                                                     ---------   ---------   ---------
                                                              (IN THOUSANDS)
<S>                                                  <C>         <C>         <C>
Unevaluated properties, not amortized..............  $  42,286   $  60,258   $ 104,075
Properties subject to amortization.................    309,378     468,062     566,868
                                                     ---------   ---------   ---------
Capitalized costs..................................    351,664     528,320     670,943
Accumulated depreciation, depletion and
  amortization.....................................   (137,769)   (171,258)   (229,776)
                                                     ---------   ---------   ---------
          Net capitalized costs....................  $ 213,895   $ 357,062   $ 441,167
                                                     =========   =========   =========
</TABLE>
 
                                      F-19
<PAGE>   126
                        THE HOUSTON EXPLORATION COMPANY
 
             NOTES TO COMBINED FINANCIAL STATEMENTS -- (CONTINUED)
 
     The following is a summary of the costs (in thousands) which are excluded
from the amortization calculation as of December 31, 1997, by year of
acquisition. The Company is not able to accurately predict when these costs will
be included in the amortization base; however, the Company believes that
unevaluated properties at December 31, 1997 will be fully evaluated within five
years.
 
<TABLE>
<CAPTION>
 
<S>                                                         <C>
1997......................................................  $ 46,546
1996......................................................    33,168
1995......................................................    13,097
Prior.....................................................    11,264
                                                            --------
                                                            $104,075
                                                            ========
</TABLE>
 
     Costs incurred for natural gas and oil exploration, development and
acquisition are summarized below. Costs incurred during the years ended December
31, 1995, 1996 and 1997 include interest expense, general and administrative
costs related to acquisition, exploration and development of natural gas and oil
properties, of $7.0 million, $8.8 million and $13.1 million, respectively.
 
<TABLE>
<CAPTION>
                                                           YEARS ENDED DECEMBER 31,
                                                         -----------------------------
                                                          1995       1996       1997
                                                         -------   --------   --------
                                                                (IN THOUSANDS)
<S>                                                      <C>       <C>        <C>
Leasehold and acquisition:
  Unevaluated(1).......................................  $ 9,902   $ 23,317   $ 16,613
  Proved...............................................   11,137     94,774     24,007
Exploration costs......................................    7,224     27,398     44,119
Development costs......................................   41,163     31,243     59,244
                                                         -------   --------   --------
          Total costs incurred.........................  $69,426   $176,732   $143,983
                                                         =======   ========   ========
</TABLE>
 
- ---------------
 
(1) These amounts represent costs incurred by the Company and excluded from the
    amortization base until proved reserves are established or impairment is
    determined.
 
 Standardized Measure of Discounted Future Net Cash Flows Relating to Proved
 Natural Gas and Oil Reserves (unaudited)
 
     The following summarizes the policies used by the Company in the
preparation of the accompanying natural gas and oil reserve disclosures,
standardized measures of discounted future net cash flows from proved natural
gas and oil reserves and the reconciliations of such standardized measures from
year to year. The information disclosed, as prescribed by the Statement of
Financial Accounting Standards No. 69 is an attempt to present such information
in a manner comparable with industry peers.
 
     The information is based on estimates of proved reserves attributable to
the Company's interest in natural gas and oil properties as of December 31 of
the years presented. These estimates were principally prepared by independent
petroleum consultants. Proved reserves are estimated quantities of natural gas
and crude oil which geological and engineering data demonstrate with reasonable
certainty to be recoverable in future years from known reservoirs under existing
economic and operating conditions.
 
     The standardized measure of discounted future net cash flows from
production of proved reserves was developed as follows:
 
          1. Estimates are made of quantities of proved reserves and future
     periods during which they are expected to be produced based on year-end
     economic conditions.
 
                                      F-20
<PAGE>   127
                        THE HOUSTON EXPLORATION COMPANY
 
             NOTES TO COMBINED FINANCIAL STATEMENTS -- (CONTINUED)
 
          2. The estimated future cash flows are compiled by applying year-end
     prices of natural gas and oil relating to the Company's proved reserves to
     the year-end quantities of those reserves except for those reserves devoted
     to future production that is hedged. The estimated future cash flows
     associated with such reserves are compiled by applying the reference prices
     of such hedges to the future production that is hedged. Future price
     changes are considered only to the extent provided by contractual
     arrangements in existence at year-end.
 
          3. The future cash flows are reduced by estimated production costs,
     costs to develop and produce the proved reserves and certain abandonment
     costs, all based on year-end economic conditions.
 
          4. Future income tax expenses are based on year-end statutory tax
     rates giving effect to the remaining tax basis in the natural gas and oil
     properties, other deductions, credits and allowances relating to the
     Company's proved natural gas and oil reserves.
 
          5. Future net cash flows are discounted to present value by applying a
     discount rate of 10 percent.
 
     The standardized measure of discounted future net cash flows does not
purport, nor should it be interpreted, to present the fair value of the
Company's natural gas and oil reserves. An estimate of fair value would also
take into account, among other things, the recovery of reserves not presently
classified as proved, anticipated future changes in prices and costs and a
discount factor more representative of the time value of money and the risks
inherent in reserve estimates.
 
     The standardized measure of discounted future net cash flows relating to
proved natural gas and oil reserves is as follows:
 
<TABLE>
<CAPTION>
                                                           AS OF DECEMBER 31,
                                                   -----------------------------------
                                                     1995         1996         1997
                                                   --------    ----------    ---------
                                                             (IN THOUSANDS)
<S>                                                <C>         <C>           <C>
Future cash inflows..............................  $418,822    $1,117,058    $ 781,336
Future production costs..........................   (66,458)     (153,452)    (135,437)
Future development costs.........................   (24,803)      (67,966)     (84,658)
Future income taxes..............................   (74,933)     (230,316)    (124,510)
                                                   --------    ----------    ---------
Future net cash flows............................   252,628       665,324      436,731
10% annual discount for estimated timing of cash
  flows..........................................   (81,169)     (212,742)    (121,351)
                                                   --------    ----------    ---------
Standardized measure of discounted future net
  cash flows.....................................  $171,459    $  452,582    $ 315,380
                                                   ========    ==========    =========
</TABLE>
 
     Future cash inflows include the effect of hedges in place at year end
December 31, 1995, 1996 and 1997. At December 31, 1995, 1996, and 1997 the
effect of the hedges in place is a reduction to future cash inflows of $4.4
million, $28.7 million and $0.5 million, respectively.
 
                                      F-21
<PAGE>   128
                        THE HOUSTON EXPLORATION COMPANY
 
             NOTES TO COMBINED FINANCIAL STATEMENTS -- (CONTINUED)
 
     The following table summarizes changes in the standardized measure of
discounted future net cash flows:
 
<TABLE>
<CAPTION>
                                                           AS OF DECEMBER 31,
                                                    ---------------------------------
                                                      1995        1996        1997
                                                    --------    --------    ---------
                                                             (IN THOUSANDS)
<S>                                                 <C>         <C>         <C>
Beginning of the year.............................  $118,434    $171,459    $ 452,582
Revisions to previous estimates:
  Changes in prices and costs.....................    35,497     145,385     (223,169)
  Changes in quantities...........................    11,306     (19,132)     (23,156)
  Changes in future development costs.............       531     (14,068)     (20,499)
Development costs incurred during the period......     8,074      19,594       16,154
Extensions and discoveries, net of related
  costs...........................................    51,061      46,616      114,893
Sales of natural gas and oil, net of production
  costs...........................................   (34,843)    (52,663)     (97,968)
Accretion of discount.............................    12,815      20,652       57,700
Net change in income taxes........................   (24,720)    (89,353)      62,733
Purchase of reserves in place.....................    11,189     251,713        2,463
Sale of reserves in place.........................       (19)       (723)        (608)
Production timing and other.......................   (17,866)    (26,898)     (25,745)
                                                    --------    --------    ---------
End of year.......................................  $171,459    $452,582    $ 315,380
                                                    ========    ========    =========
</TABLE>
 
ESTIMATED NET QUANTITIES OF NATURAL GAS AND OIL RESERVES (UNAUDITED)
 
     The following table sets forth the Company's net proved reserves, including
changes therein, and proved developed reserves (all within the United States) at
the end of each of the three years in the period ended December 31, 1995, 1996
and 1997.
 
<TABLE>
<CAPTION>
                                        NATURAL GAS             CRUDE OIL AND CONDENSATE
                                          (MMCF)                         (MBBLS)
                               -----------------------------    -------------------------
                                1995       1996       1997      1995      1996      1997
                               -------    -------    -------    -----    ------    ------
<S>                            <C>        <C>        <C>        <C>      <C>       <C>
Proved developed and
  undeveloped reserves:....    145,945    195,946    320,474     636       889     1,131
  Revisions of previous
     estimates.............     15,702     (8,665)   (18,743)     51      (157)      (62)
  Extensions and
     discoveries...........     45,014     21,445     75,651     254       198       184
  Production...............    (21,077)   (31,215)   (50,310)   (100)     (118)     (171)
  Purchase of reserves
     in place..............     10,367    143,688      3,778      48       361         1
  Sales of reserves in
     place.................         (5)      (725)      (249)     --       (42)       (6)
                               -------    -------    -------    ----     -----     -----
End of year................    195,946    320,474    330,601     889     1,131     1,077
                               =======    =======    =======    ====     =====     =====
Proved developed reserves:
  Beginning of year........    104,678    162,784    236,544     328       774     1,013
  End of year..............    162,784    236,544    256,632     774     1,013       914
</TABLE>
 
                                      F-22
<PAGE>   129
                        THE HOUSTON EXPLORATION COMPANY
 
             NOTES TO COMBINED FINANCIAL STATEMENTS -- (CONTINUED)
 
NOTE 14 -- QUARTERLY FINANCIAL INFORMATION (UNAUDITED)
 
     Selected unaudited quarterly data is shown below:
 
<TABLE>
<CAPTION>
                                                1ST        2ND        3RD        4TH
                                              QUARTER    QUARTER    QUARTER    QUARTER
                                              -------    -------    -------    -------
                                               (IN THOUSANDS, EXCEPT PER SHARE DATA)
<S>                                           <C>        <C>        <C>        <C>
1996
  Total revenues..........................    $10,213    $11,574    $19,171    $24,946
  Income from operations..................      1,219      2,661      2,740      7,102
  Net income (loss).......................        976      1,813      1,267      4,586
  Net income per share(1).................    $  0.06    $  0.12    $  0.08    $  0.20
  Net income per share -- assuming
     dilution.............................    $  0.06    $  0.12    $  0.08    $  0.19
1997
  Total revenues..........................    $25,328    $22,220    $29,312    $40,786
  Income from operations..................      8,287      4,337      8,065     13,672
  Net income..............................      5,693      3,442      5,525      8,590
  Net income per share....................    $  0.24    $  0.15    $  0.24    $  0.37
  Net income per share -- assuming
     dilution.............................    $  0.24    $  0.14    $  0.23    $  0.35
</TABLE>
 
- ---------------
 
(1) Quarterly earnings per share are based on the weighted average number of
    shares outstanding during the quarter. Because of the increase in the number
    of shares outstanding during the third quarter of 1996, the sum of quarterly
    earnings per share do not equal earnings per share for the year.
 
                                      F-23
<PAGE>   130
 
======================================================
 
     ALL TENDERED OLD NOTES, EXECUTED LETTERS OF TRANSMITTAL AND OTHER RELATED
DOCUMENTS SHOULD BE DIRECTED TO THE EXCHANGE AGENT. QUESTIONS AND REQUESTS FOR
ASSISTANCE AND REQUESTS FOR ADDITIONAL COPIES OF THE PROSPECTUS, THE LETTER OF
TRANSMITTAL AND OTHER RELATED DOCUMENTS SHOULD BE ADDRESSED TO THE EXCHANGE
AGENT AS FOLLOWS:
 
                        By Registered or Certified Mail:
 
                              THE BANK OF NEW YORK
                             101 Barclay Street, 7E
                            New York, New York 10286
                            Attention: Marcia Brown
 
                     By Overnight Courier or Hand Delivery:
 
                              THE BANK OF NEW YORK
                               101 Barclay Street
                        Corporate Trust Services Window
                                  Ground Level
                            New York, New York 10286
                            Attention: Marcia Brown
 
                           By Facsimile Transmission:
 
                        (for Eligible Institutions only)
                                 (212) 815-6339
                            Attention: Marcia Brown
 
                             Confirm by Telephone:
 
                                 (212) 815-3428
 
(Originals of all documents submitted by facsimile should be sent promptly by
hand, overnight delivery, or registered or certified mail.)
 
                             ---------------------
 
     NO DEALER, SALESPERSON OR ANY OTHER PERSON HAS BEEN AUTHORIZED TO GIVE ANY
INFORMATION OR MAKE ANY REPRESENTATIONS NOT CONTAINED IN THIS PROSPECTUS AND, IF
GIVEN OR MADE, SUCH INFORMATION OR REPRESENTATIONS MUST NOT BE RELIED UPON AS
HAVING BEEN AUTHORIZED BY THE COMPANY OR ANY OF THE INITIAL PURCHASERS. THIS
PROSPECTUS DOES NOT CONSTITUTE AN OFFER TO SELL, OR SOLICITATION OF AN OFFER TO
BUY, TO ANY PERSON IN ANY JURISDICTION WHERE SUCH OFFER OR SOLICITATION WOULD BE
UNLAWFUL. NEITHER THE DELIVERY OF THIS PROSPECTUS NOR ANY SALE MADE HEREUNDER
SHALL, UNDER ANY CIRCUMSTANCES, CREATE ANY IMPLICATION THAT THE INFORMATION
CONTAINED HEREIN IS CORRECT AS OF ANY TIME SUBSEQUENT TO THE DATE HEREOF.
======================================================
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                                  $100,000,000
 
                           (HOUSTON EXPLORATION LOGO)
 
                           8 5/8% SENIOR SUBORDINATED
                                 NOTES DUE 2008
                               -----------------
 
                                   PROSPECTUS
                               -----------------
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
                                        PAGE
                                        ----
<S>                                     <C>
Disclosure Regarding Forward-Looking
  Statements..........................    2
Prospectus Summary....................    3
Risk Factors..........................   16
The Company...........................   23
The Exchange Offer....................   24
Use of Proceeds.......................   32
Capitalization........................   32
Selected Combined Financial Data......   33
Management's Discussion and Analysis
  of Financial Condition and Results
  of Operations.......................   34
Business..............................   42
Management............................   60
Certain Transactions..................   63
Description of the Notes..............   66
Certain United States Federal Income
  Tax Considerations..................   99
Plan of Distribution..................  101
Legal Matters.........................  102
Independent Public Accountants........  102
Reserve Engineers.....................  102
Available Information.................  102
Incorporation of Certain Information
  by Reference........................  103
Glossary of Oil and Gas Terms.........  G-1
Index to Financial Statements.........  F-1
</TABLE>
 
                                  May 15, 1998
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