HELMERICH & PAYNE INC
8-K, 1996-09-12
DRILLING OIL & GAS WELLS
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<PAGE>   1





                       SECURITIES AND EXCHANGE COMMISSION

                            Washington, D.C.  20549

                                    FORM 8-K

                                 CURRENT REPORT


                        Pursuant to Section 13 or 15(d)
                     of the Securities Exchange Act of 1934

                       Date of Report: September 12, 1996



                            HELMERICH & PAYNE, INC.
- --------------------------------------------------------------------------------
            (Exact name of registrant as specified in its charter)



    Delaware                           1-4221                      73-0679879
- --------------------------------------------------------------------------------
(State or other                     (Commission File            (I.R.S. Employer
jurisdiction of                         Number)                  Identification
incorporation)                                                      Number)


Utica at Twenty-first Street, Tulsa, Oklahoma                        74114
- --------------------------------------------------------------------------------
(Address of principal executive offices)                          (Zip Code)


                                  (918) 742-5531
- --------------------------------------------------------------------------------
             (Registrant's telephone number, including area code)


                                      N/A
- --------------------------------------------------------------------------------
         (Former name or former address, if changed since last report)
<PAGE>   2
ITEM 2.  ACQUISITION OR DISPOSITION OF ASSETS.

         On August 23, 1996, Helmerich & Payne, Inc., a Delaware corporation
("Registrant"), Natural Gas Odorizing, Inc., an Oklahoma corporation ("NGO"),
Occidental Petroleum Corporation, a Delaware corporation  ("Buyer"), and OPC
Acquisition Corp., an Oklahoma corporation ("OPC"), entered into an Agreement
and Plan of Merger ("Agreement") pursuant to which Buyer agreed to purchase all
of Registrant's chemical odorant business located in Baytown, Texas (the
"Business") pursuant to a tax-free merger between Registrant's wholly-owned
subsidiary NGO and Buyer's wholly-owned subsidiary OPC.  NGO is a producer and
marketer of mercaptan-based products used primarily as warning odorants in
natural gas and liquified petroleum gas.  NGO also produces related products
used as feed stocks and sulfiding agents in other segments of the chemical
industry.

         On August 30, 1996 ("Closing"), the sale of the Business was
consummated such that OPC was merged with and into NGO with NGO being the
surviving corporation.  In consideration of such disposition, Registrant
received 2,018,928 shares of Buyer's common stock which equaled approximately
$48 million as of Closing.  The number of shares received by Registrant was
calculated based upon a formula such that each share of NGO common stock (being
500 shares at Closing) would be converted into that number of shares of Buyer's
common stock which equaled the quotient obtained by dividing $96,000 by the
Closing Stock Price as defined in the Agreement.  The Agreement contains no
provision for any post-closing adjustments to the purchase price.  Except as
specifically provided in the Agreement, NGO generally retained all liabilities
of the Business regardless of whether such liabilities arose before, on and
after Closing.

ITEM 7.  FINANCIAL STATEMENTS AND EXHIBITS.

         (a) Financial Statements of Businesses Acquired.

             Not Applicable.

         (b) Pro Forma Financial Information

         The following unaudited pro forma condensed consolidated financial
         statements are filed with this report:

             Pro Forma Condensed Consolidated Statement of Income 
             for the Year Ended September 30, 1993  . . . . . . . . . Page F-1






                                       2
<PAGE>   3
             Pro Forma Condensed Consolidated Statement of Income
             for the Year Ended September 30, 1994  . . . . . . . . . Page F-2

             Pro Forma Condensed Consolidated Statement of Income 
             for the Year Ended September 30, 1995  . . . . . . . . . Page F-3

             Pro Forma Condensed Consolidated Statement of Income 
             for the Nine Months Ended June 30, 1996  . . . . . . . . Page F-4

             Pro Forma Condensed Consolidated Balance Sheet at 
             June 30, 1996  . . . . . . . . . . . . . . . . . . . . . Page F-5

         The Pro Forma Condensed Consolidated Balance Sheet of Registrant as of
June 30, 1996, reflects the financial position of Registrant after giving
effect to the disposition of Registrant's chemical odorant Business discussed
in Item 2 and assumes the disposition took place on June 30, 1996.  The Pro
Forma Condensed Consolidated Statements of Income for the fiscal years ended
September 30, 1993, 1994 and 1995, and the nine months ended June 30, 1996,
assume that the disposition occurred at the beginning of each respective
period, and are based on the operations of Registrant for the years ended
September 30, 1993, 1994 and 1995, and the nine months ended June 30, 1996.
The Pro Forma Condensed Consolidated Balance Sheet also reflects the receipt by
Registrant of 2,018,928 shares of Buyer's common stock pursuant to the
transaction referred to in Item 2.

         The unaudited pro forma condensed consolidated financial statements
have been prepared by Registrant based upon assumptions deemed proper by
Registrant.  The unaudited pro forma condensed consolidated financial
statements presented herein are shown for illustrative purposes only and are
not necessarily indicative of the future financial position or future results
of Registrant, or the financial position or results of operations of Registrant
that would have actually occurred had the transaction been in effect as of the
date or for the periods presented.  In addition, it should be noted that
Registrant's financial statements will reflect the disposition only from the
Closing date of August 30, 1996.

         The unaudited pro forma condensed consolidated financial statements
should be read in conjunction with historical financial statements and related
notes of Registrant.





                                       3
<PAGE>   4
         (c) Exhibits.

<TABLE>
<CAPTION>
   NO.                            DESCRIPTION
   ---                            -----------
   <S>      <C>
    2       Agreement and Plan of Merger among Helmerich & Payne, Inc., Natural
            Gas Odorizing, Inc., OPC Acquisition Corp., and Occidental Petroleum
            Corporation dated August 23, 1996.
</TABLE>

Registrant has omitted from this Form 8-K all Schedules  (Schedules  1-A - 7.4)
attached to the Agreement and Plan of Merger.  These Schedules are identified
on page vi of the Agreement and Plan of Merger.  Registrant will furnish the
Commission with a copy of any of the omitted Schedules upon request.





                                       4
<PAGE>   5
                                   SIGNATURES

         Pursuant to the requirements of the Securities Exchange Act of 1934,
the Registrant has duly caused this report to be signed on its behalf by the
undersigned, thereunto duly authorized.

                                           HELMERICH & PAYNE, INC.
                                               (Registrant)



                                           By:   /s/ Steven R. Mackey         
                                                ------------------------------

                                                Name:    Steven R. Mackey
                                                Title:   Vice President,
                                                         Secretary and General
                                                         Counsel


Dated:   September 12, 1996





                                       5
<PAGE>   6
                       PRO FORMA FINANCIAL INFORMATION


                  HELMERICH & PAYNE, INC. AND SUBSIDIARIES
            PRO FORMA CONDENSED CONSOLIDATED STATEMENT OF INCOME
                    FOR THE YEAR ENDED SEPTEMBER 30, 1993
                                 (UNAUDITED)
         (DOLLARS AND SHARES IN THOUSANDS EXCEPT PER SHARE AMOUNTS)



<TABLE>
<CAPTION>
                                                                      ADJUSTMENTS
                                                             --------------------------------
                                                  HISTORICAL         NGO (A)        PRO FORMA     PRO FORMA
                                              ---------------------------------------------------------------
<S>                                                 <C>              <C>                  <C>       <C>     
REVENUES                                                                                          
  Sales and other operating revenues                $306,047         $14,374                        $291,673
  Income from investments                              9,050                                           9,050
                                              ---------------------------------------------------------------
                                                     315,097          14,374               0         300,723
                                              ---------------------------------------------------------------
                                                                                                  
                                                                                                  
COSTS AND EXPENSES                                                                                
  Operating costs                                    194,856           9,696                         185,160
  Depreciation, depletion and amortization            48,609             594                          48,015
  Dry holes and abandonments                           6,893               0                           6,893
  Taxes, other than income taxes                      13,763             419                          13,344
  General and administrative                           6,820                                           6,820
  Interest                                               925                                             925
                                              ---------------------------------------------------------------
                                                     271,866          10,709                         261,157
                                              ---------------------------------------------------------------
                                                                                                  
 Income before income taxes and equity                                                            
   in income of affiliate                             43,231           3,665                          39,566
                                                                                                  
Income tax expense                                    18,279           1,259                          17,020
Equity in income(loss) of affiliate                                                               
    net of income taxes                                 (402)                                           (402)
                                                                                                  
                                              ===============================================================
NET INCOME                                           $24,550          $2,406              $0         $22,144
                                              ===============================================================
                                              ===============================================================
                                                                                                  
- -------------------------------------------------------------------------------------------------------------
                                                                                                  
Average shares outstanding                            24,307                                          24,307
                                                                                                  
NET INCOME PER SHARE                                   $1.01           $0.10                           $0.91
                                                                                                  
- -------------------------------------------------------------------------------------------------------------
</TABLE>

(a) To eliminate the results of operations of NGO for the entire period.




                                      F-1

<PAGE>   7


                        PRO FORMA FINANCIAL INFORMATION


                    HELMERICH & PAYNE, INC. AND SUBSIDIARIES
              PRO FORMA CONDENSED CONSOLIDATED STATEMENT OF INCOME
                     FOR THE YEAR ENDED SEPTEMBER 30, 1994
                                  (UNAUDITED)
           (DOLLARS AND SHARES IN THOUSANDS EXCEPT PER SHARE AMOUNTS)



<TABLE>
<CAPTION>
                                                                                    ADJUSTMENTS
                                                                           --------------------------------
                                                                HISTORICAL         NGO (A)        PRO FORMA    PRO FORMA
                                                            --------------------------------------------------------------
<S>                                                               <C>              <C>                  <C>      <C>     
REVENUES                                                                                                       
  Sales and other operating revenues                              $322,698         $18,849                       $303,849
  Income from investments                                            6,303                                          6,303
                                                            --------------------------------------------------------------
                                                                   329,001          18,849               0        310,152
                                                            --------------------------------------------------------------
                                                                                                               
                                                                                                               
COSTS AND EXPENSES                                                                                             
  Operating costs                                                  213,427          11,790                        201,637
  Depreciation, depletion and amortization                          50,068             654                         49,414
  Dry holes and abandonments                                        10,369                                         10,369
  Taxes, other than income taxes                                    15,545             411                         15,134
  General and administrative                                         8,908                                          8,908
  Interest                                                             385                                            385
                                                            --------------------------------------------------------------
                                                                   298,702          12,855                        285,847
                                                            --------------------------------------------------------------
                                                                                                               
Income before income taxes, equity in income of                                                               
   of affiliate and cumulative effect of change in                                                             
   accounting principle                                             30,299           5,994                         24,305
                                                                                                               
Income tax expense                                                  10,232           2,131                          8,101
Equity in income of affiliate                                                                                  
    net of income taxes                                                904                                            904
                                                                                                               
Net Income Before Cumulative Effect of Change in            ==============================================================
    Accounting Principle.                                          $20,971          $3,863              $0        $17,108
                                                            ==============================================================
                                                            ==============================================================
                                                                                                               
- --------------------------------------------------------------------------------------------------------------------------
                                                                                                               
Average shares outstanding                                          24,416                                         24,416
                                                                                                               
Net Income Per Share Before Cumulative Effect of Change                                                        
   in Accounting Principle                                           $0.86           $0.16                          $0.70
                                                                                                               
- --------------------------------------------------------------------------------------------------------------------------
</TABLE>

(a) To eliminate the results of operations of NGO for the entire period.




                                      F-2

<PAGE>   8

                        PRO FORMA FINANCIAL INFORMATION


                    HELMERICH & PAYNE, INC. AND SUBSIDIARIES
              PRO FORMA CONDENSED CONSOLIDATED STATEMENT OF INCOME
                     FOR THE YEAR ENDED SEPTEMBER 30, 1995
                                  (UNAUDITED)
           (DOLLARS AND SHARES IN THOUSANDS EXCEPT PER SHARE AMOUNTS)



<TABLE>
<CAPTION>
                                                                       ADJUSTMENTS
                                                              --------------------------------
                                                   HISTORICAL         NGO (A)        PRO FORMA     PRO FORMA
                                               ---------------------------------------------------------------
<S>                                                  <C>              <C>                            <C>     
REVENUES                                                                                           
  Sales and other operating revenues                 $314,930         $19,055                        $295,875
  Income from investments                              10,846                                          10,846
                                               ---------------------------------------------------------------
                                                      325,776          19,055               0         306,721
                                               ---------------------------------------------------------------
                                                                                                   
                                                                                                   
COSTS AND EXPENSES                                                                                 
  Operating costs                                     200,240          11,743                         188,497
  Depreciation, depletion and amortization             77,115             672                          76,443
  Dry holes and abandonments                           10,096               1                          10,095
  Taxes, other than income taxes                       15,408             418                          14,990
  General and administrative                            8,801                                           8,801
  Interest                                                407                                             407
                                               ---------------------------------------------------------------
                                                      312,067          12,834                         299,233
                                               ---------------------------------------------------------------
                                                                                                   
Income before income taxes and equity                                                             
   in income of affiliate                              13,709           6,221                           7,488
                                                                                                   
Income tax expense                                      5,044           2,258                           2,786
Equity in income of affiliate                                                                      
    net of income taxes                                 1,086                                           1,086
                                                                                                   
                                               ===============================================================
NET INCOME                                             $9,751          $3,963              $0          $5,788
                                               ===============================================================
                                               ===============================================================
                                                                                                   
- --------------------------------------------------------------------------------------------------------------
                                                                                                   
Average shares outstanding                             24,536                                          24,536
                                                                                                   
NET INCOME PER SHARE                                    $0.40           $0.16                           $0.24
                                                                                                   
- --------------------------------------------------------------------------------------------------------------
</TABLE>

(a) To eliminate the results of operations of NGO for the entire period.




                                      F-3
<PAGE>   9


                        PRO FORMA FINANCIAL INFORMATION


                    HELMERICH & PAYNE, INC. AND SUBSIDIARIES
              PRO FORMA CONDENSED CONSOLIDATED STATEMENT OF INCOME
                    FOR THE NINE MONTHS ENDED JUNE 30, 1996
                                  (UNAUDITED)
           (DOLLARS AND SHARES IN THOUSANDS EXCEPT PER SHARE AMOUNTS)



<TABLE>
<CAPTION>
                                                                       ADJUSTMENTS
                                                              --------------------------------
                                                   HISTORICAL         NGO (A)        PRO FORMA     PRO FORMA
                                               ---------------------------------------------------------------
<S>                                                  <C>              <C>                  <C>       <C>     
REVENUES                                                                                           
  Sales and other operating revenues                 $297,408         $16,535                        $280,873
  Income from investments                               4,125                                           4,125
                                               ---------------------------------------------------------------
                                                      301,533          16,535               0         284,998
                                               ---------------------------------------------------------------
                                                                                                   
                                                                                                   
COSTS AND EXPENSES                                                                                 
  Operating costs                                     175,016          10,038                         164,978
  Depreciation, depletion and amortization             42,728             600                          42,128
  Dry holes and abandonments                            6,555                                           6,555
  Taxes, other than income taxes                       13,617             404                          13,213
  General and administrative                            6,970                                           6,970
  Interest                                                390                                             390
                                               ---------------------------------------------------------------
                                                      245,276          11,042                         234,234
                                               ---------------------------------------------------------------
                                                                                                   
Income before income taxes and equity                                                             
   in income of affiliate                              56,257           5,493                          50,764
                                                                                                   
Income tax expense                                     21,672           2,135                          19,537
Equity in income of affiliate                                                                      
    net of income taxes                                   693                                             693
                                                                                                   
                                               ===============================================================
NET INCOME                                            $35,278          $3,358              $0         $31,920
                                               ===============================================================
                                               ===============================================================
                                                                                                   
- --------------------------------------------------------------------------------------------------------------
                                                                                                   
Average shares outstanding                             24,666                                          24,666
                                                                                                   
NET INCOME PER SHARE                                    $1.43           $0.14                           $1.29
                                                                                                   
- --------------------------------------------------------------------------------------------------------------
</TABLE>

(a) To eliminate the results of operations of NGO for the entire period.




                                      F-4
<PAGE>   10

                        PRO FORMA FINANCIAL INFORMATION


                    HELMERICH & PAYNE, INC. AND SUBSIDIARIES
        PRO FORMA CONDENSED CONSOLIDATED BALANCE SHEET AT JUNE 30, 1996
                                  (UNAUDITED)



<TABLE>
<CAPTION>
                                                                              ADJUSTMENTS
                                                                     --------------------------------
                                                          HISTORICAL         NGO (A)        PRO FORMA (B)  PRO FORMA
                                                      ---------------------------------------------------------------
                                                                           (Dollars in thousands)               
<S>                                                          <C>                <C>          <C>             <C>    
ASSETS                                                                                                    
CURRENT ASSETS                                                                                            
   Cash and cash equivalents                                 $16,286            $727                         $15,559
   Short-term investments                                      1,005              --                           1,005
   Accounts receivable                                        75,596           2,919                          72,677
   Inventories                                                20,784           1,944                          18,840
   Other current assets                                        5,094              69                           5,025
                                                      ---------------------------------------------------------------
       TOTAL CURRENT ASSETS                                  118,765           5,659               0         113,106
                                                      ---------------------------------------------------------------
                                                                                                          
Investments                                                  178,528              --          48,000         226,528
                                                                                                          
Property, Plant and Equipment                              1,073,498          15,289                       1,058,209
Accumulated depreciation and amortization                    612,622           9,048                         603,574
                                                      ---------------------------------------------------------------
   Net Property, Plant and Equipment                         460,876           6,241               0         454,635
                                                      ---------------------------------------------------------------
                                                                                                          
Other Assets                                                  14,402              60                          14,342
                                                                                                          
                                                      ===============================================================
       TOTAL ASSETS                                         $772,571         $11,960         $48,000        $808,611
                                                      ===============================================================
                                                      ===============================================================
                                                                                                          
LIABILITIES AND SHAREHOLDERS' EQUITY                                                                      
CURRENT LIABILITIES                                                                                       
   Accounts payable                                          $26,718          $1,357                         $25,361
   Accrued liabilities                                        23,746             879           1,119          23,986
   Income taxes payable                                       10,454             245             228          10,437
   Notes payable                                               6,000              --                           6,000
                                                      ---------------------------------------------------------------
       TOTAL CURRENT LIABILITIES                              66,918           2,481           1,347          65,784
                                                      ---------------------------------------------------------------
                                                                                                          
NONCURRENT LIABILITIES                                                                                    
   Deferred income taxes                                      80,669             134          14,520          95,055
   Other                                                      15,566             958                          14,608
                                                      ---------------------------------------------------------------
       TOTAL NONCURRENT LIABILITIES                           96,235           1,092          14,520         109,663
                                                      ---------------------------------------------------------------
                                                                                                          
       TOTAL SHAREHOLDERS' EQUITY                            609,418           8,387          32,133         633,164
                                                      ===============================================================
       TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY           $772,571         $11,960         $48,000        $808,611
                                                      ===============================================================
                                                      ===============================================================
                                                                                                          
                                                                                                          
- ---------------------------------------------------------------------------------------------------------------------
</TABLE>

(a)   To eliminate the assets and liabilities included in the balance sheet of
      the Company's wholly owned subsidiary Natural Gas Odorizing, Inc. (NGO")
      as of June 30, 1996.

(b)   To reflect the value of 2,018,928 shares of Occidental Petroleum common
      stock received from the sale of NGO, and the transaction costs and
      income tax liabilities related to the transaction.




                                      F-5
<PAGE>   11
                               INDEX TO EXHIBITS



<TABLE>
<CAPTION>
Exhibit No.    Exhibit                                              Page
- -----------    -------                                              ----
    <S>        <C>                                                  <C>
    2          Agreement and Plan of Merger among Helmerich &
               Payne, Inc., Natural Gas Odorizing, Inc., OPC
               Acquisition Corp., and Occidental Petroleum
               Corporation dated August 23, 1996.
</TABLE>






<PAGE>   1
                                                                [Conformed Copy]




================================================================================




                          AGREEMENT AND PLAN OF MERGER


                                     AMONG


                       OCCIDENTAL PETROLEUM CORPORATION,


                             OPC ACQUISITION CORP.,


                            HELMERICH & PAYNE, INC.


                                      AND


                          NATURAL GAS ODORIZING, INC.




                                AUGUST 23, 1996






================================================================================


<PAGE>   2





                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                               Page
                                                                                               ----
<S>      <C>                                                                                     <C>
                                                        ARTICLE I

                          DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  1

                                                        ARTICLE II

                          TERMS OF THE TRANSACTION  . . . . . . . . . . . . . . . . . . . . . .  10

2.1      The Merger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  10
2.2      Effective Time of Merger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  10
2.3      Conversion of Stock  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  11
2.4      Closing  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  11
2.5      Effect of the Merger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  14
2.6      Taking of Necessary Action; Further Action . . . . . . . . . . . . . . . . . . . . . .  15

                                                       ARTICLE III

                          REPRESENTATIONS AND WARRANTIES OF H&P . . . . . . . . . . . . . . . .  15

3.1      Organization of H&P and NGO  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  15
3.2      Qualification and Corporate Power of NGO . . . . . . . . . . . . . . . . . . . . . . .  15
3.3      Charter and By-laws of NGO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  16
3.4      Capitalization of NGO  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  16
3.5      Authority Relative to this Agreement and the
                 Related Documents  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  16
3.6      Noncontravention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  17
3.7      Consents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  17
3.8      Subsidiaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  18
3.9      Financial Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  18
3.10     Absence of Undisclosed Liabilities . . . . . . . . . . . . . . . . . . . . . . . . . .  18
3.11     Books and Records  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  18
3.12     Title to Properties  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  19
3.13     Accounts Receivable  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  19
3.14     Inventory  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  19
3.15     Absence of Certain Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  19
3.16     Employee Benefits  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  19
3.17     Labor Relations  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  24
</TABLE>





<PAGE>   3




<TABLE>
<CAPTION>
                                                                                               Page
                                                                                               ----
<S>      <C>                                                                                     <C>
3.18     Legal Proceedings; Orders  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  25
3.19     Compliance With Laws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  25
3.20     Permits  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  25
3.21     Contracts; No Defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  26
3.22     Discharge of Obligations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
3.23     Material Personal Property . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
3.24     Real Property  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
3.25     Banking Arrangements of NGO  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
3.26     Insurance  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
3.27     Environmental Matters  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  29
3.28     Intellectual Property  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  31
3.29     Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  31
3.30     Foreign Assets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  31
3.31     Claims by Directors and Officers, Etc. of NGO  . . . . . . . . . . . . . . . . . . . .  31
3.32     Brokers or Finders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  31
3.33     Investment Intent  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  31
3.34     Regulated Industry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  31
3.35     Limitation on Representations and Warranties by H&P  . . . . . . . . . . . . . . . . .  32

                                                        ARTICLE IV

                          REPRESENTATIONS AND WARRANTIES OF
                                     OCCIDENTAL . . . . . . . . . . . . . . . . . . . . . . . .  32

4.1      Organization of Occidental and the Company . . . . . . . . . . . . . . . . . . . . . .  32
4.2      Authority Relative to this Agreement and the
                 Related Documents  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  32
4.3      Noncontravention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  33
4.4      Consents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  34
4.5      Shares of Occidental Common Stock  . . . . . . . . . . . . . . . . . . . . . . . . . .  34
4.6      SEC Filings  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  34
4.7      Legal Proceedings  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  35
4.8      Brokers or Finders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  35
4.9      Investment Intent  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  35
4.10     Limitation on Representations and Warranties
                  by Occidental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  35
</TABLE>





                                       ii
<PAGE>   4




<TABLE>
<CAPTION>
                                                                                               Page
                                                                                               ----
<S>      <C>                                                                                     <C>
                                                        ARTICLE V

                          CONDUCT OF NGO PENDING CLOSING  . . . . . . . . . . . . . . . . . . .  36

5.1      Operation of the Business of NGO . . . . . . . . . . . . . . . . . . . . . . . . . . .  36
5.2      Restrictions on Certain Actions  . . . . . . . . . . . . . . . . . . . . . . . . . . .  36

                                                        ARTICLE VI

                          ADDITIONAL AGREEMENTS . . . . . . . . . . . . . . . . . . . . . . . .  38

6.1      General  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  38
6.2      Required Consents  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  38
6.3      Access to Information  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  38
6.4      Notification of Certain Matters  . . . . . . . . . . . . . . . . . . . . . . . . . . .  38
6.5      No Shopping  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  39
6.6      Permits  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  39
6.7      Employees and Employee Benefit Plans . . . . . . . . . . . . . . . . . . . . . . . . .  39
6.8      No Intercompany Indebtedness or Obligations  . . . . . . . . . . . . . . . . . . . . .  41
6.9      Books and Records  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  41
6.10     Litigation Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  42
6.11     Securities Laws and Transfers; Stock Certificates  . . . . . . . . . . . . . . . . . .  42
6.12     No Short Sales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  43
6.13     Title Matters  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  43
6.14     Insurance  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  44
6.15     Listing of Shares of the Occidental Common Stock . . . . . . . . . . . . . . . . . . .  45

                                                       ARTICLE VII

                          TAX MATTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  45
7.1      Representations, Warranties and Covenants of H&P . . . . . . . . . . . . . . . . . . .  45
7.2      Representations, Warranties and Covenants of Occidental  . . . . . . . . . . . . . . .  46
7.3      Refunds, Carryover, Etc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  48
7.4      Indemnification for Taxes  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  48
7.5      Contest Provision  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  49
7.6      Cooperation  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  49
7.7      Transfer Taxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  50
7.8      Survival . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  50
7.9      Conduct of H&P Before Closing  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  50
</TABLE>





                                      iii
<PAGE>   5




<TABLE>
<CAPTION>
                                                                                               Page
                                                                                               ----
<S>      <C>                                                                                     <C>
                                                       ARTICLE VIII

                          CONDITIONS TO OBLIGATIONS OF OCCIDENTAL
                                 AND THE COMPANY  . . . . . . . . . . . . . . . . . . . . . . .  50

8.1      Accuracy of Representations  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  50
8.2      Performance by H&P and NGO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  51
8.3      No Proceedings or Orders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  51
8.4      Consents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  51
8.5      Novation Agreement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  51
8.6      Delivery of Documents  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  51
8.7      Legal Matters  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  51

                                                        ARTICLE IX

                          CONDITIONS TO OBLIGATIONS OF H&P AND NGO  . . . . . . . . . . . . . .  51

9.1      Accuracy of Representations  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  52
9.2      Performance by Occidental and the Company  . . . . . . . . . . . . . . . . . . . . . .  52
9.3      No Proceedings or Orders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  52
9.4      Consents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  52
9.5      Novation Agreement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  52
9.6      Delivery of Documents  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  52
9.7      Legal Matters  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  52

                                                        ARTICLE X

                          TERMINATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  53

10.1     Termination Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  53
10.2     Effect of Termination  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  53

                                                        ARTICLE XI

                          SURVIVAL OF REPRESENTATIONS AND
                                WARRANTIES  . . . . . . . . . . . . . . . . . . . . . . . . . .  54

11.1     Survival . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  54
</TABLE>





                                       iv
<PAGE>   6





<TABLE>
<CAPTION>
                                                                                               Page
                                                                                               ----
<S>     <C>                                                                                      <C>
                                                       ARTICLE XII

                          MISCELLANEOUS . . . . . . . . . . . . . . . . . . . . . . . . . . . .  55

12.1     Confidentiality  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  55
12.2     Press Releases and Public Announcements  . . . . . . . . . . . . . . . . . . . . . . .  55
12.3     No Third-Party Beneficiaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  55
12.4     Entire Agreement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  56
12.5     Expenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  56
12.6     Brokerage Indemnities  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  56
12.7     Indemnification Arrangements for Directors and
                Officers, Etc.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  56
12.8     Notices  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  57
12.9     Amendments and Waivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  57
12.10   Assignment; Successors and Assigns  . . . . . . . . . . . . . . . . . . . . . . . . . .  58
12.11   Payments  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  58
12.12   Severability  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  59
12.13   Headings  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  59
12.14   Governing Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  59
12.15   Counterparts  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  59
12.16   Construction  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  59
12.17   Incorporation of Exhibits and Schedules . . . . . . . . . . . . . . . . . . . . . . . .  59
</TABLE>





                                       v
<PAGE>   7




                        INDEX TO SCHEDULES AND EXHIBITS

<TABLE>
<S>                      <C>
Schedule 1-A                                                            Knowledge
Schedule 3.2                             Qualification and Corporate Power of NGO
Schedule 3.6                                                     Noncontravention
Schedule 3.10                                  Absence of Undisclosed Liabilities
Schedule 3.13                                                 Accounts Receivable
Schedule 3.15                                          Absence of Certain Changes
Schedule 3.16                                                   Employee Benefits
Schedule 3.17                                                     Labor Relations
Schedule 3.18                                           Legal Proceedings; Orders
Schedule 3.19                                                Compliance With Laws
Schedule 3.20                                                             Permits
Schedule 3.21                                                           Contracts
Schedule 3.22                                            Discharge of Obligations
Schedule 3.24                                                       Real Property
Schedule 3.25                                                Banking Arrangements
Schedule 3.26.1                                                         Insurance
Schedule 3.26.2                                                         Insurance
Schedule 3.26.3                                                         Insurance
Schedule 3.26.4                                                         Insurance
Schedule 3.26.5                                                         Insurance
Schedule 3.27                                               Environmental Matters
Schedule 3.28                                               Intellectual Property
Schedule 3.30                                                      Foreign Assets
Schedule 4.3                                                     Noncontravention
Schedule 5.2                                      Restrictions on Certain Actions
Schedule 6.7                                 Employees and Employee Benefit Plans
Schedule 7.4                                                        Accrued Taxes
                         
                         
Exhibit A                                           Form of Certificate of Merger
Exhibit B                                              Form of Novation Agreement
Exhibit C                                          Form of Registration Agreement
Exhibit 2.4(b)(x)                       Form of Opinion of Counsel to H&P and NGO
Exhibit 2.4(c)(vii)      Form of Opinion of Counsel to Occidental and the Company
Exhibit 2.4(c)(viii)            Form of Opinion of Special Counsel for Occidental
                                              and the Company
</TABLE>





                                       vi
<PAGE>   8





                          AGREEMENT AND PLAN OF MERGER


         AGREEMENT AND PLAN OF MERGER, dated as of August 23, 1996, among
Occidental Petroleum Corporation, a Delaware corporation, OPC Acquisition
Corp., an Oklahoma corporation, Helmerich & Payne, Inc., a Delaware
corporation, and Natural Gas Odorizing, Inc., an Oklahoma corporation.

                                  WITNESSETH:

         WHEREAS, NGO (as such term and certain other terms used in this
Agreement with initial capital letters are defined in Article I) is a
wholly-owned subsidiary of H&P; and

         WHEREAS, the Company is a wholly-owned subsidiary of Occidental; and

         WHEREAS, the respective boards of directors of NGO and the Company
have approved the Merger in accordance with the provisions of Title 18, Section
1081 of the OGCA; and

         WHEREAS, Occidental, as the sole shareholder of the Company, and H&P,
as the sole shareholder of NGO, have approved the Merger in accordance with the
provisions of Title 18, Section 1081 of the OGCA; and

         WHEREAS, the Parties intend for this transaction to qualify as a
tax-free reorganization pursuant to the provisions of Section 368(a) of the
Code;

         NOW, THEREFORE, in consideration of the premises and the mutual
covenants and agreements herein contained, the Parties, intending to be legally
bound hereby, agree as follows:

                                   ARTICLE I

                                  DEFINITIONS

         For purposes of this Agreement, the following terms shall have the
meanings specified or referred to in this Article I:

         "Affiliate" means any Person that is an "affiliate" within the meaning
of the regulations promulgated under the Securities Act, as such regulations
and Act shall be amended and in effect on the date of this Agreement.  NGO
shall (i), with respect to all periods of time prior to, and immediately
before, the Closing, be an Affiliate of H&P, and (ii), with respect to all
periods of time after, and commencing upon, the Closing, and so long as owned
by Occidental or any of its Affiliates, be an Affiliate of Occidental.





<PAGE>   9





         "Agreement" means this Agreement and Plan of Merger, including the
Exhibits and Schedules hereto, as the same may be amended in accordance with
the provisions hereof.

         "Applicable Contract" means any Contract (i) under which NGO is
entitled to any property or rights, (ii) under which NGO has any obligation or
liability, or (iii) by which NGO or any of the Assets is bound.

         "Applicable Law" means any Law to which a specified Person or its
property is subject, including, without limitation, all Environmental Laws.

         "Assets" means any and all properties and assets (real, personal or
mixed, tangible or intangible) Owned by NGO.

         "Audit" means any audit, assessment of Taxes, other examination by any
Tax Authority, proceeding or appeal of such proceeding relating to Taxes.

         "Balance Sheet" has the meaning set forth in Section 3.9.

         "Banked Vacation" has the meaning set forth in Section 6.7(g).

         "Baytown Land" means the real property, containing approximately 30
acres and being located in Baytown, Texas, described on Schedule 3.24.

         "Business Day" means any day, other than a Saturday, Sunday or a day
on which banking institutions in Tulsa, Oklahoma, are required or authorized by
law to close.

         "CERCLA" means the Comprehensive Environmental Response, Compensation
and Liability Act of 1980, 42 U.S.C.  Section  9601, et seq., as amended.

         "Certificate of Merger" means a Certificate of Merger of NGO in
substantially the form set forth as Exhibit A.

         "Cleanup" has the meaning set forth in clause (d) of the definition of
Environmental Liabilities.

         "Closing" has the meaning set forth in Section 2.4(a).

         "Closing Date" has the meaning set forth in Section 2.4(a).

         "Closing Stock Price" means the average of the last reported sales
prices (regular way) of the Occidental Common Stock on the New York Stock
Exchange on each of the





                                       2
<PAGE>   10




five consecutive trading days ending on (and including) the third trading day
prior to the Closing Date.

         "Code" means the Internal Revenue Code of 1986, as amended.  All
citations to the Code, or to the Treasury Regulations promulgated thereunder,
shall include any amendments thereto or any substitute or successor provisions
thereof.

         "Company" means OPC Acquisition Corp., an Oklahoma corporation.

         "Company Common Stock" means the Common Stock, par value $1.00 per
share, of the Company.

         "Confidential Memorandum" means the Confidential Memorandum, dated
Winter 1996, of Smith Barney Inc. pertaining to NGO.

         "Confidentiality Agreement" means the letter, dated January 8, 1996,
between Smith Barney Inc., on behalf of H&P, and Occidental.

         "Consent" means any approval, consent, order, ratification, waiver or
other authorization (including any Governmental Authorization) of any Person.

         "Constituent Corporations" means the Company and NGO.

         "Contract" means any agreement, contract, obligation, mortgage, note,
lease, license, franchise, guaranty, promise, letter of credit, instrument,
commitment, arrangement, understanding or undertaking of any kind (whether
written or oral, express or implied).

         "Defensible Title" means, with respect to any property or assets of
NGO:

                 (i)      Title to such property or asset is free and clear of
         all Encumbrances, other than Permitted Encumbrances;

                 (ii)     The rights and interest of NGO in such property or
         asset shall not be subject to being reduced in the future, whether by
         virtue of the exercise by a third party of reversionary, back-in or
         similar rights or otherwise; and

                 (iii)    NGO shall not be in default under any material
         provision of any Applicable Contract, materially and adversely
         affecting the value of such property or asset or the operation
         thereof.

         "Deferred Compensation Agreement" means the Deferred Compensation
Agreement, dated August 17, 1984, as amended, between H&P and Mr. J. T.
Johnson.





                                       3
<PAGE>   11





         "Effective Time" means the date and time when the Merger shall become
effective.

         "Employees" has the meaning set forth in Section 6.7(a).

         "Encumbrance" means any charge, claim, encumbrance, mortgage,
conditional sale agreement, title retention agreement, financing lease,
community property interest, condition, equitable interest, lien, option,
pledge, security interest, right of first refusal, or restriction of any kind,
including any restriction on use, voting, transfer, receipt of income, or
exercise of any other attribute of ownership, and whether arising by Contract
or under Law.

         "Environment" means soil, land surface or subsurface strata, surface
waters (including navigable waters, ocean waters, streams, ponds, drainage
basins and wetlands), groundwaters, drinking water supply, stream sediments,
ambient air (including indoor air), plant and animal life, and any other
environmental medium or natural resource.

         "Environmental Law" means any Law that pertains to the regulation or
protection of human health or the Environment (including CERCLA; the Solid
Waste Disposal Act, as amended by the Resource Conservation and Recovery Act of
1976, 42 U.S.C. Section  6901, et seq.; the Toxic Substances Control Act of
1976, 15 U.S.C. Section  2501, et seq.; the Superfund Amendments and
Reauthorization Act of 1986, Title III, 42 U.S.C. Section  11001, et seq.; the
Clear Air Act, 42 U.S.C. Section  7401, et seq.; the Federal Water Pollution
Control Act or Clean Water Act, 33 U.S.C. Section  1251, et seq.; the Safe
Drinking Water Act, 42 U.S.C. Section  300f, et seq.; the Hazardous Materials
Transportation Act, 49 U.S.C. Section  1801, et seq.; the Occupational Safety
and Health Act of 1970, 29 U.S.C. Section  651, et seq.; and all state and
local laws of similar purpose and effect) and all amendments or recodifications
to any such Law as of the date of this Agreement.

         "Environmental Liabilities" means any cost, damages, expense,
liability, obligation or other responsibility arising from or under
Environmental Law, including:

         (a)     any environmental matter or condition (including the Release,
Threatened Release or presence of any Hazardous Materials in any form in the
Environment);

         (b)     any Permits, actions, fixtures or equipment necessary to
conduct any Hazardous Activity or to control, monitor, treat or eliminate the
Release or Threatened Release of Hazardous Materials from any Hazardous
Activity;

         (c)     fines, penalties, judgments, awards, settlements, legal or
administrative proceedings, damages, losses, claims, demands, attorneys' fees
and costs, consultants' fees and costs, and response, investigation, remedial
or inspection costs and expenses arising under Environmental Law;





                                       4
<PAGE>   12





         (d)     financial responsibility under Environmental Law for cleanup
costs or corrective action, including any investigation, cleanup, removal,
containment, or other remediation or response action ("Cleanup") required by
applicable Environmental Law (whether or not such Cleanup has been required or
requested by any Governmental Body or any other Person) and for any natural
resource damage; and

         (e)     any other compliance, corrective, investigative, or remedial
measure required under Environmental Law.

The terms "removal", "remedial" and "response action" include the types of
activities covered by CERCLA.

         "EPA" has the meaning set forth in Section 3.27(d).

         "Equity Securities" of any Person means the capital or voting stock of
such Person and all other securities convertible into, or exchangeable or
exercisable for, any shares of such capital or voting stock, all rights to
subscribe for or to purchase, all options and warrants for the purchase of, and
all calls, commitments or claims of any character relating to, any shares of
such capital or voting stock, all equity equivalents, interests in the
ownership or earnings or other similar rights of, or with respect to, such
Person, and any securities convertible into or exchangeable or exercisable for
any of the foregoing.

         "ERISA" means the Employee Retirement Income Security Act of 1974, as
amended, or any successor law, and the regulations and rules issued pursuant to
the provisions of such Act or any such successor law.

         "ERISA Affiliate" has the meaning set forth in Section 3.16(a).

         "ERISA Plans" has the meaning set forth in Section 3.16(a).

         "Facilities" means any real property, leaseholds or other interests
currently or formerly owned and operated by NGO and any buildings, plants,
structures or equipment (including motor vehicles, tank cars and rolling stock)
currently or formerly owned or operated by NGO.

         "Financial Statements" has the meaning set forth in Section 3.9.

         "GAAP" means generally accepted accounting principles in the United
States of America.

         "Governmental Authorization" means any approval, consent, license,
permit, waiver or other authorization issued, granted, given or otherwise made
available by, or under the authority of, any Governmental Body or pursuant to
any Law.





                                       5
<PAGE>   13





         "Governmental Body" means any (i) federal, state, local, municipal,
foreign or other government, (ii) governmental or quasi-governmental authority
of any nature (including any governmental agency, branch, department,
commission, board, bureau, official or other entity and any court or other
tribunal in any jurisdiction), or (iii) body exercising, or entitled to
exercise, any administrative, executive, judicial, legislative, police,
regulatory or taxing authority or power of any nature.

         "Hazardous Activity" means the disposal, distribution, generation,
handling, importing, management, manufacturing, processing, production,
recycling, refinement, Release, Threatened Release, storage, transfer,
transportation, treatment or use of Hazardous Materials by, or on behalf of,
H&P or NGO or in, on, under, about or from the Facilities or any part thereof,
or any other act, business, operation, condition or thing that poses or
increases a danger, risk of danger or risk of harm to Persons, property or the
Environment on or off the Facilities or that may affect the value of NGO.

         "Hazardous Materials" means any chemical, product, intermediate, waste
or other substance that is listed, defined, designated or classified as, or
otherwise determined to be, hazardous, radioactive or toxic or a pollutant or a
contaminant under, or pursuant to, any Environmental Law, including (i) any
admixture or solution thereof, and (ii) any solvent, explosive, polychlorinated
biphenyls, asbestos, petroleum or petroleum product or byproduct.

         "Helmerich & Payne Group" has the meaning set forth in Section
7.1(a)(3).

         "HSR Act" means the Hart-Scott-Rodino Antitrust Improvements Act of
1976, as amended, or any successor law.

         "H&P" means Helmerich & Payne, Inc., a Delaware corporation.

         "Information" has the meaning set forth in Section 12.1.

         "Intellectual Property Rights" means any and all interests in patents,
patent applications, copyrights, copyright registrations, applications for the
registration of copyrights, trademarks, trademark registrations and
applications therefor, service marks, service mark registrations and
applications therefor, trade names (whether or not registered or registrable),
trade-secrets, know-how, engineering data, maps, technical information and
other intangible properties, in each case used by NGO in its business.

         "Knowledge" means conscious awareness of a fact or other matter by an
individual listed on Schedule 1-A.

         "Law" means any law, Order, constitution, ordinance, principle of
common law, regulation, rule, Permit condition, statute or treaty of any
Governmental Body.





                                       6
<PAGE>   14





         "Letter of Intent" means the letter, dated May 15, 1996, between
Occidental and H&P.

         "Merger" has the meaning set forth in Section 2.1.

         "National Union Policy" means H&P's policy number 309-00-25, insured
with National Union Fire Insurance Company of Pittsburgh, Pennsylvania, and
having a term, with respect to NGO, of September 30, 1994 to September 30,
1996.

         "NGO" means Natural Gas Odorizing, Inc., an Oklahoma corporation.

         "NGO Common Stock" means the Common Stock, par value $1.00 per share,
of NGO.

         "NGO Shares" means the issued and outstanding shares of the NGO Common
Stock.

         "Novation Agreement" means the Novation Agreement, dated the Closing
Date, among H&P, Occidental and National Union Fire Insurance Company of
Pittsburgh, PA., in substantially the form set forth as Exhibit B.

         "Occidental" means Occidental Petroleum Corporation, a Delaware
corporation.

         "Occidental Common Stock" means the Common Stock, par value $.20 per
share, of Occidental.

         "Occidental Financial Statements" has the meaning set forth in Section
4.6.

         "Occidental Reports" has the meaning set forth in Section 4.6.

         "OGCA" means the Oklahoma General Corporation Act (Title 18, Oklahoma
Statutes Annotated, Section 1001, et seq.).

         "Order" means any award, decision, injunction, judgment, order,
ruling, writ, decree or verdict entered, issued, made or rendered by (i) any
court, administrative agency or other Governmental Body, or (ii) any
arbitrator.

         "Ordinary Course of Business" of any Person means any action taken by
such Person that (i) is consistent with the past practices of such Person, and
(ii) is taken in the ordinary course of the normal day-to-day operations of
such Person.

         "Owned" means, with respect to NGO, those properties and assets (real,
personal or mixed, tangible or intangible) owned, leased or otherwise held by
NGO.

         "Parties" means Occidental, the Company, H&P and NGO.





                                       7
<PAGE>   15




         "PBGC" has the meaning set forth in Section 3.16(f).

         "Pension Plans" has the meaning set forth in Section 3.16(a).

         "Permit" means any license, permit, franchise, consent, certification,
approval or other authorization of, or from, any Governmental Body.

         "Permitted Encumbrances" means any and all of the following
Encumbrances or title defects affecting any of the properties of NGO:

                 (i)      Liens for taxes and assessments that are not yet
         delinquent or which are being contested by NGO in good faith and with
         respect to which adequate provisions for reserves have been made on
         the books of NGO;

                 (ii)     Rights existing under Applicable Laws or operating
         agreements or similar Contracts to assert liens against any properties
         of NGO, but not including liens and other rights that have actually
         been asserted, unless (A) NGO disputes the validity of any such lien
         or the amount claimed to be owed in connection therewith and adequate
         reserves therefor have been made on the books of NGO, or (B) such lien
         or other right is not enforceable against the interest of NGO;

                 (iii)    Recorded easements and rights-of-way, and unrecorded
         easements and rights-of-way, for streets, alleys, highways, telephone
         lines, power lines or railways that do not, actually or potentially,
         materially and adversely affect the property or its current use;

                 (iv)     Any obligations or duties affecting any property to
         any municipality or public authority with respect to any Permit, all
         Applicable Laws, and all rules and order of any Governmental Body of
         general application to owners of similar properties;

                 (v)      Any Encumbrance incidental to the conduct of the
         business of NGO or the ownership by NGO of the Assets which was not
         incurred in connection with the borrowing of money or the obtaining of
         advances or credit and which does not materially detract from the
         value of the Asset to which such Encumbrance relates or materially
         impair the use of such Asset in the operation of such business;

                 (vi)     Any Encumbrance set forth on Schedule 3.24; and

                 (vii)    Any Encumbrance, title defect or other matter waived
         in writing by Occidental.





                                       8
<PAGE>   16





         "Person" means any individual, corporation (including any non-profit
corporation), partnership, limited liability company, joint venture, estate,
trust, association, joint stock company, enterprise, joint venture,
organization, labor union, business, Governmental Body or other entity.

         "Plans" has the meaning set forth in Section 3.16(a).

         "Proceeding" means any proceeding, action, arbitration, claim,
hearing, litigation, investigation, inquiry or suit commenced, brought,
conducted, or heard by or before, or otherwise involving, any Governmental Body
or any arbitrator.

         "PUHCA" means the Public Utility Holding Company Act of 1935, as
amended.

         "Registration Agreement" means the Registration Agreement, dated the
Closing Date, between H&P and Occidental in substantially the form set forth as
Exhibit C.

         "Related Documents" means (i) the Certificate of Merger, (ii) the
Novation Agreement, and (iii) the Registration Agreement.

         "Release" means any spilling, leaking, emitting, discharging,
depositing, escaping, migrating, leaching, dumping or other releasing into the
Environment, whether intentional or unintentional.

         "Representative" means, with respect to any Person, any director,
officer, employee, agent, consultant, contractor, advisor or other
representative of such Person, including legal counsel, accountants and
financial advisors.

         "SEC" means the Securities and Exchange Commission.

         "Securities Act" means the Securities Act of 1933, as amended, or any
successor law.

         "SPD" has the meaning set forth in Section 3.16(c).

         "Survey" means the survey, dated July 26, 1996, relating to, among
other things, the Baytown Land and prepared by the Surveyor.

         "Surveyor" means Walsh Surveying Inc.

         "Surviving Corporation" has the meaning set forth in Section 2.1.

          "Tax Authority" means the Internal Revenue Service and any other
domestic or foreign governmental authority responsible for the administration
of any Taxes.





                                       9
<PAGE>   17





         "Tax Returns" means all federal, state, local and foreign tax returns,
declarations, statements, reports, schedules, forms and information returns
(including any amendments thereto) relating to Taxes.

         "Taxes" means all federal, state, local and foreign income, profit,
franchise, sales, use, payroll, occupation, property and excise taxes,
assessments, levies, imposts, duties or other governmental charges of a similar
nature (whether imposed directly or through withholding), including any
interest, additions to tax, or penalties applicable thereto.

         "Termination Date" means September 30, 1996.

         "Threatened Release" means a substantial likelihood of a Release that
may require action in order to prevent or mitigate damage to the Environment
that may result from such Release.

         "Title Commitment" has the meaning set forth in Section 6.13(a).

         "Title Company" means Charter Title Company, Houston, Texas.

         "Title Policy" has the meaning set forth in Section 6.13(a).

         "TNRCC" has the meaning set forth in Section 3.27(d).

         "Welfare Plans" has the meaning set forth in Section 3.16(a).

                                   ARTICLE II

                            TERMS OF THE TRANSACTION

         Section 2.1      THE MERGER.  Upon the terms and subject to the
conditions set forth in this Agreement, and in accordance with the provisions
of the OGCA, the Company shall be merged (the "Merger") with and into NGO,
which shall be the surviving corporation in the Merger (NGO being herein
sometimes referred to as the "Surviving Corporation").  The Articles of
Incorporation and By-laws of NGO in effect upon the consummation of the Merger
shall continue to be the Articles of Incorporation and By-laws of the Surviving
Corporation.  The directors and officers of the Company upon consummation of
the Merger shall be the directors and officers of the Surviving Corporation.

         Section 2.2      EFFECTIVE TIME OF MERGER.  The Merger shall become
effective upon the filing by NGO of the Certificate of Merger (together with
any other documents required by law to effectuate the Merger) with the
Secretary of State of the State of Oklahoma, which filing shall be made by NGO,
immediately prior to, or simultaneously with, the Closing, in accordance with
the provisions of Title 18, Section 1081.C. of the OGCA.





                                       10
<PAGE>   18





         Section 2.3      CONVERSION OF STOCK.  At the Effective Time:

         (a)     Each share of the NGO Common Stock which shall be issued and
outstanding immediately prior to the Effective Time shall, by virtue of the
Merger and without any action on the part of H&P, be converted into the right
to receive that number of shares of the Occidental Common Stock (rounded to the
nearest thousandth of a share, with .0005 of a share rounded upwards) which
shall be equal to the quotient obtained by dividing $96,000 by the Closing
Stock Price; provided, however, that, in the event that the actual Closing
Stock Price shall be less than $21.50, (i) the Closing Stock Price shall be
deemed, for purposes of this Section 2.3(a), to be $21.50, and (ii) H&P shall
have the right to terminate this Agreement pursuant to the provisions of
Section 10.1(iv).

         (b)     Each share of the Company Common Stock which shall be issued
and outstanding immediately prior to the Effective Time shall, by virtue of the
Merger and without any action on the part of the Company or Occidental, be
converted into one share of the NGO Common Stock (the common stock of the
Surviving Corporation).

         (c)     H&P shall cease to have any rights with respect to the NGO
Shares, except, upon surrender by H&P, in accordance with the provisions of
clause (i) of Section 2.4(b), of all certificates which, prior to the Effective
Time, represented the NGO Shares, the right to receive the consideration
specified in Section 2.3(a).

         (d)     Occidental shall have all rights with respect to the shares of
the NGO Common Stock (the common stock of the Surviving Corporation).

         Section 2.4      CLOSING.

         (a)     The closing for the Merger (the "Closing") shall take place
(i) at the offices of H&P, 1579 E. 21st Street, Tulsa, Oklahoma, at 10:00 a.m.
(local time) on the earlier to occur of (A) the Termination Date, and (B) that
day that is two consecutive Business Days after the day on which the last of
the conditions to the obligations of the Parties set forth in Articles VIII and
IX shall be fulfilled or waived (subject to Applicable Law) or are capable of
being fulfilled at the Closing, or (ii) such other time or place or on such
other date as the Parties shall agree.  The date on which the Closing is
required to take place is herein referred to as the "Closing Date".

         (b)     At the Closing, H&P shall deliver to Occidental the following:

                 (i)      All certificates which, prior to the Effective Time,
         represented the NGO Shares, endorsed in blank by an officer of H&P;

                 (ii)     A certificate executed on behalf of H&P by the
         President or any Vice President of H&P, dated the Closing Date,
         certifying, to the best of such officer's knowledge, in such detail as
         Occidental may reasonably request, that the conditions set forth in
         Article VIII have been fulfilled and that neither H&P nor





                                       11
<PAGE>   19




          NGO is in breach of any provision of this Agreement to be observed or
          performed by H&P or NGO;

                 (iii)    The minute books, stock records and corporate seal of
         NGO, certified as complete and correct as of the Closing Date by the
         Secretary or any Assistant Secretary of H&P;

                 (iv)     The written resignations of such directors and
         officers of NGO as Occidental shall, at least 3 days prior to the
         Closing Date, specify in writing to H&P, such resignations to be
         effective at the Closing Date;

                 (v)      A letter, dated the Closing Date, from each director
         and officer of NGO stating that such individual does not have any
         pending claim for indemnification from NGO and is not aware of any
         facts that might form the basis for such a claim;

                 (vi)     A copy of each of (A) the resolutions of the Board of
         Directors of H&P authorizing the execution, delivery and performance
         by H&P of this Agreement and of each of the Related Documents to which
         H&P is a party, and (B) the by-laws  of H&P, certified as of the
         Closing Date by the Secretary or any Assistant Secretary of H&P;

                 (vii)    A copy of each of (A) the resolutions of the Board of
         Directors of NGO authorizing the execution, delivery and performance
         by NGO of this Agreement and of each of the Related Documents to which
         NGO is a party, and (B) the by-laws of NGO, certified as of the
         Closing Date by the Secretary or any Assistant Secretary of NGO;

                 (viii)   A copy of the consent to action without a meeting of
         the sole shareholder of NGO, certified as of the Closing Date by the
         Secretary or any Assistant Secretary of H&P, pursuant to the
         provisions of Title 18, Section 1081.C. of the OGCA;

                 (ix)     A certificate or certificates from the Secretary of
         State of each of the States of Delaware and Oklahoma, dated not more
         than three Business Days prior to the Closing Date, certifying as to
         the charter documents, and the good standing and corporate existence,
         of H&P and NGO, respectively;

                 (x)      An opinion of Steven R. Mackey, Esq., Vice President
         and General Counsel of H&P and legal counsel to H&P and NGO, dated the
         Closing Date, in substantially the form of Exhibit 2.4(b)(x);

                 (xi)     A copy of the Registration Agreement, duly executed
         by an authorized officer of H&P;

                 (xii)    A copy of the Novation Agreement, duly executed by an
         authorized officer of each of H&P;





                                       12
<PAGE>   20





                 (xiii)   A certificate executed by the Secretary or any
         Assistant Secretary of NGO, dated the Closing Date, pursuant to the
         provisions of Title 18, Section 1081.C. of the OGCA;

                 (xiv)    A copy of all written reports, correspondence and
         analytical data which (A) represent, summarize or interpret results of
         testing or sampling of environmental media at the Baytown Land, and
         (B) have been generated or prepared on behalf of H&P or NGO by their
         respective consultants, contractors or outside legal counsel prior to
         the Closing; and

                 (xv)     A receipt, dated the Closing Date, of H&P for the
         certificate representing the shares of the Occidental Common Stock
         issued by Occidental to H&P upon conversion of the shares of NGO
         Common Stock.

                 (c)      At the Closing, Occidental shall deliver to H&P the
following:

                 (i)      A certificate representing the number of shares
         (rounded to the nearest whole share, with five-tenths of a share
         rounded upwards) of the Occidental Common Stock determined by
         multiplying (A) 500, by (B) the number of shares of the Occidental
         Common Stock into which one share of the NGO Common Stock shall have
         been converted at the Effective Time, registered in the name of H&P;

                 (ii)     A certificate executed on behalf of Occidental by the
         President, any Executive Vice President, any Vice President or the
         Treasurer of Occidental, dated the Closing Date, certifying, to the
         best of such officer's knowledge, in such detail as H&P may reasonably
         request, that the conditions set forth in Article IX have been
         fulfilled and that neither Occidental nor the Company is in breach of
         any provision of this Agreement to be observed or performed by
         Occidental or the Company;

                 (iii)    A copy of each of (A) the resolutions of the Board of
         Directors of Occidental (or of any committee of such Board of
         Directors) authorizing the execution, delivery and performance by
         Occidental of this Agreement and of each of the Related Documents to
         which Occidental is a party, and (B) the by-laws of Occidental,
         certified as of the Closing Date by the Secretary or any Assistant
         Secretary of Occidental;

                 (iv)     A copy of each of (A) the resolutions of the Board of
         Directors of the Company authorizing the execution, delivery and
         performance by the Company of this Agreement, and (B) the by-laws of
         the Company, certified as of the Closing Date by the Secretary or any
         Assistant Secretary of the Company;





                                       13
<PAGE>   21





                 (v)      A copy of the consent to action without a meeting of
         the sole shareholder of the Company, certified as of the Closing Date
         by the Secretary or any Assistant Secretary of Occidental, pursuant to
         the provisions of Title 18, Section 1081.C. of the OGCA;

                 (vi)     A certificate or certificates from the Secretary of
         State of each of the States of Delaware and Oklahoma, dated not more
         than three Business Days prior to the Closing Date, certifying as to
         the charter documents, and the good standing and corporate existence,
         of Occidental and the Company, respectively;

                 (vii)    An opinion of Robert E. Sawyer, Esq., an Associate
         General Counsel of Occidental, dated the Closing Date, in
         substantially the form of Exhibit 2.4(c)(vii);

                 (viii)   An opinion of Gable Gotwals Mock Schwabe, special
         counsel for Occidental and the Company in connection with this
         transaction, dated the Closing Date, in substantially the form of
         Exhibit 2.4(c)(viii);

                 (ix)     A copy of the Registration Agreement, duly executed
         by an authorized officer of Occidental;

                 (x)      A copy of the Novation Agreement, duly executed by an
         authorized officer of Occidental;

                 (xi)     A certificate executed by the Secretary or any
         Assistant Secretary of the Company, dated the Closing Date, pursuant
         to the provisions of Title 18, Section 1081.C. of the OGCA;

                 (xii)    A copy of all written reports, correspondence and
         analytical data which (A) represent, summarize or interpret results of
         testing or sampling of environmental media at the Baytown Land, and
         (B) have been generated or prepared on behalf of Occidental by its
         consultants, contractors or outside legal counsel prior to the
         Closing; and

                 (xiii)   A receipt, dated the Closing Date, of Occidental for
         the certificates referred to in clause (i) of Section 2.4(b).

         Section 2.5      EFFECT OF THE MERGER.   At the Effective Time, the
separate existence of the Company having been merged into NGO shall cease, and
NGO being the Surviving Corporation shall possess all the rights, privileges,
powers and franchises as well of a public as of a private nature, and being
subject to all the restrictions, disabilities and duties of each of the
Constituent Corporations so merged; and all and singular, the rights,
privileges, powers and franchises of each of the Constituent Corporations, and
all property, real, personal and mixed, and all debts due to any of the
Constituent Corporations on whatever account, as well for stock subscriptions
as all other things in





                                       14
<PAGE>   22




action or belonging to each of the Constituent Corporations shall be vested in
the Surviving Corporation; and all property, rights, privileges, powers and
franchises, and all and every other interest shall be thereafter as effectually
the property of the Surviving Corporation as they were of the several and
respective Constituent Corporations, and the title to any real estate vested by
deed or otherwise in any of the Constituent Corporations shall not revert or be
in any way impaired by reason of the Merger; but all rights of creditors and
all liens upon any property of any of the Constituent Corporations shall be
preserved unimpaired, and all debts, liabilities and duties of the respective
Constituent Corporations, from that time forward, shall attach to the Surviving
Corporation and may be enforced against it to the same extent as if said debts,
liabilities and duties had been incurred or contracted by it.

         Section 2.6      TAKING OF NECESSARY ACTION; FURTHER ACTION.  H&P
shall (and shall cause NGO to), and Occidental shall (and shall cause the
Company to), take all such reasonable and lawful action as may be necessary or
appropriate in order to consummate or implement the transactions contemplated
hereby (including the Merger) in accordance with the terms hereof or otherwise
as promptly as possible.  In the event that, at any time after the Closing
Date, any such further action shall be necessary or desirable to carry out the
purposes of this Agreement, each of H&P and Occidental shall, and shall direct
their respective Representatives to, take all such further action (including
the execution and delivery of such further instruments and documents) as H&P or
Occidental, as the case may be, may reasonably request; provided, however, that
this Section 2.6 shall not be deemed to require any Party to expend funds or
incur obligations not otherwise expressly required pursuant to the provisions
of this Agreement or the Registration Agreement.

                                  ARTICLE III

                     REPRESENTATIONS AND WARRANTIES OF H&P

         H&P represents and warrants to Occidental that:

         Section 3.1      ORGANIZATION OF H&P AND NGO.  H&P is a corporation
duly incorporated, validly existing and in good standing under the laws of the
State of Delaware with full corporate power and authority to own, lease and
operate its properties and to carry on its business as it is now being
conducted. NGO is a corporation duly incorporated, validly existing and in good
standing under the laws of the State of Oklahoma with full corporate power and
authority to own, lease and operate its properties and to carry on its business
as it is now being conducted.  No dissolution, liquidation or bankruptcy
proceeding is pending, contemplated or threatened against either H&P or NGO.

         Section 3.2      QUALIFICATION AND CORPORATE POWER OF NGO.  NGO has
all requisite corporate power and authority to own, lease and operate the
Assets and to carry on the business in which it is engaged and is duly
qualified or licensed to do business as a foreign corporation and is in good
standing under the laws of each state or other





                                       15
<PAGE>   23




jurisdiction in which either the ownership or use of the Assets owned or used
by it, or the nature of the activities conducted by it, requires such
qualification.  Schedule 3.2 contains a complete and accurate list of the
jurisdictions in which NGO is so qualified or licensed to do business.

         Section 3.3      CHARTER AND BY-LAWS OF NGO.  H&P has made available
to Occidental accurate and complete copies of (i) the charter and by-laws of
NGO as currently in effect, (ii) the stock records of NGO, and (iii) the
minutes of all meetings of the Board of Directors of NGO, any committees of
such Board of Directors, and the shareholders of NGO (and all consents in lieu
of such meetings).  Such records, minutes and consents accurately reflect the
stock ownership of NGO and all actions taken by such Board of Directors,
committees and shareholders.  NGO is not in violation of any provision of its
charter or by-laws.

         Section 3.4      CAPITALIZATION OF NGO.  The authorized capital stock
of NGO consists of 20,000 shares of the NGO Common Stock, of which 500 shares
are issued and outstanding, and no shares of the NGO Common Stock are held in
NGO's treasury.  All of the NGO Shares have been validly issued and are fully
paid and nonassessable, and no shares of the NGO Common Stock are subject to,
nor have any been issued in violation of, any preemptive or similar rights.
All of the NGO Shares are held, beneficially and of record, by H&P and are free
and clear of any Encumbrances.  Except as set forth above in this Section 3.4,
there are outstanding (i) no Equity Securities of NGO, and (ii), except for the
obligations of H&P and Occidental pursuant to the provisions of this Agreement,
no options or other rights to acquire from H&P or NGO, and no obligation of H&P
or NGO to issue or sell, any Equity Securities of NGO.  There are no (A)
outstanding obligations of NGO to repurchase, redeem or otherwise acquire any
shares of its capital stock, or (B) Contracts relating to the issuance, sale or
transfer of any Equity Securities or other securities of NGO.

         Section 3.5      AUTHORITY RELATIVE TO THIS AGREEMENT AND THE RELATED
DOCUMENTS.  H&P has all requisite corporate power and authority (i) to execute
and deliver this Agreement and each of the Related Documents to which it is a
party, (ii) to consummate the transactions contemplated hereby and thereby, and
(iii) to perform the obligations of H&P hereunder and thereunder, including the
execution, delivery and performance of all agreements and documents necessary
to effectuate the transactions contemplated hereby and thereby.  NGO has all
requisite corporate power and authority (A) to execute and deliver this
Agreement and each of the Related Documents to which it is a party, (B) to
consummate the transactions contemplated hereby and thereby, and (C) to perform
the obligations of NGO hereunder and thereunder, including the execution,
delivery and performance of all agreements and documents necessary to
effectuate the transactions contemplated hereby and thereby.  The execution and
delivery by H&P of, and the performance by H&P of its obligations under, this
Agreement and each of the Related Documents to which it is a party have been
duly authorized by all requisite corporate action on the part of H&P, and no
other corporate proceedings on the part of H&P are necessary to authorize the
execution, delivery and performance by H&P of this





                                       16
<PAGE>   24




Agreement and each of such Related Documents and the consummation by H&P of the
transactions contemplated hereby and thereby.  The execution and delivery by
NGO of, and the performance by NGO of its obligations under, this Agreement and
each of the Related Documents to which it is a party have been duly authorized
by all requisite corporate action on the part of NGO, and no other corporate
proceedings on the part of NGO or its sole shareholder are necessary to
authorize the execution, delivery and performance by NGO of this Agreement and
each of such Related Documents and the consummation by NGO of the transactions
contemplated hereby and thereby.  This Agreement has been duly executed and
delivered by H&P and NGO and constitutes (and each of the Related Documents to
which H&P or NGO is a party, and each other agreement, instrument or document
executed or to be executed by H&P or NGO in connection with the transactions
contemplated hereby or thereby, has been, or when executed will be, duly
executed and delivered by H&P or NGO, as the case may be, and constitutes, or
when so executed and delivered will constitute) a valid and legally binding
obligation of H&P or NGO enforceable against H&P or NGO, as the case may be, in
accordance with its terms, except that such enforceability may be limited by
applicable bankruptcy, insolvency, reorganization, moratorium or similar laws
affecting creditors' rights generally and equitable principles (whether applied
in a court of law or equity).

         Section 3.6      NONCONTRAVENTION.  Except as set forth on Schedule
3.6, (i) the execution, delivery and performance by H&P and NGO of this
Agreement and each of the Related Documents to which H&P or NGO is a party, and
(ii) the consummation by H&P and NGO of the transactions contemplated by this
Agreement or each of such Related Documents do not and will not (A) contravene,
conflict with, or result in a breach or violation of, any of the terms,
provisions or conditions of, (1) the charter or by-laws of H&P or NGO, (2) any
resolution adopted by the Board of Directors or the stockholders of H&P or NGO,
or (3) any Order or Permit to which H&P or NGO, or any of their respective
properties and assets, may be subject, (B) contravene, conflict with, or result
in a breach or violation of, any of the terms, provisions or conditions of, or
constitute (with or without the giving of notice or the passage of time or
both) a default under, or give rise (with or without the giving of notice or
the passage of time or both) to any right of termination, amendment,
cancellation or acceleration of, or require payment under, any bond, debenture,
note, mortgage, indenture, lease or other Contract to which H&P or NGO is a
party or by which H&P or NGO or any of their respective properties or assets
may be bound or affected, (C) result in the imposition or creation of any
Encumbrance upon, or with respect to, any of the NGO Shares or the properties
or assets owned or used by NGO, or (D), assuming compliance with the matters
referred to in Section 3.7, violate any Law binding upon H&P or NGO.

         Section 3.7      CONSENTS.  No Consent of, or declaration, filing or
registration with, any Person (including any Governmental Body) is required to
be obtained or made by H&P or NGO in connection with (i) the execution,
delivery or performance by H&P or NGO of this Agreement or any of the Related
Documents to which H&P or NGO is a party, or (ii) the consummation by H&P or
NGO of the transactions contemplated by this Agreement or any of such Related
Documents, other than (A) compliance with the





                                       17
<PAGE>   25




applicable requirements of the HSR Act, (B) compliance with any applicable
state securities or takeover laws, (C) the filing by NGO of the Certificate of
Merger with the Secretary of State of the State of Oklahoma, and (D) other
filings with Governmental Bodies in the Ordinary Course of Business of H&P or
NGO that are not required to be made prior to the consummation of the
transactions contemplated by this Agreement or such Related Documents.

         Section 3.8      SUBSIDIARIES.  NGO does not own, directly or
indirectly, any Equity Securities or other securities of any corporation or
have any direct or indirect equity or ownership interest in, or right to elect
directors, managers or trustees (or any Person performing similar functions)
of, any other Person.

         Section 3.9      FINANCIAL STATEMENTS.  NGO has delivered to
Occidental complete and correct copies of (i) the audited balance sheet of NGO
for the six months ended March 31, 1996 (the "Balance Sheet"), and the related
audited statements of income, shareholder's equity and cash flows for such six
months, and (ii) the audited balance sheets of NGO, and the related audited
statements of income, shareholders' equity and cash flows, for the fiscal years
of NGO ended September 30, 1994 and 1995 (collectively, the "Financial
Statements").  The Financial Statements (A) have been prepared from the books
and records of NGO and, except as disclosed in the report of independent
auditors included therewith, in conformity with GAAP, and (B) accurately and
fairly present the financial condition and the results of operations and cash
flows of NGO as of the respective dates of, and for the periods referred to in,
the Financial Statements, all in accordance with GAAP, subject, in the case of
the Financial Statements as of and for the six months ended March 31, 1996, to
normal recurring year-end adjustments, none of which could reasonably be
expected to be material.  The Financial Statements reflect the consistent
application of GAAP throughout the periods involved, except as disclosed in
such report of independent auditors.

         Section 3.10     ABSENCE OF UNDISCLOSED LIABILITIES.  NGO does not
have, and, since the date of the Balance Sheet, NGO has not incurred, any
liability or obligation (whether asserted or unasserted, accrued or unaccrued,
absolute or contingent, liquidated or unliquidated, due or to become due, or
otherwise), except (i) liabilities reflected on the Balance Sheet, (ii) current
liabilities which have arisen since the date of the Balance Sheet in the
Ordinary Course of Business of NGO (none of which is a material liability for
breach of contract, tort or infringement), and (iii) liabilities disclosed on
Schedule 3.10.

         Section 3.11     BOOKS AND RECORDS.  The books of account, minute
books, stock record books, and other records of NGO, all of which have been
made available to Occidental, are, to the best of the Knowledge of H&P,
complete and correct in all material respects and accurately and fairly
reflect, in reasonable detail, the transactions that have taken place involving
the business of NGO.  At the Closing, all of such books and records will be in
the possession of NGO.





                                       18
<PAGE>   26





         Section 3.12     TITLE TO PROPERTIES.  NGO owns, and has Defensible
Title to, all of the properties and assets (whether real, personal or mixed and
whether tangible or intangible) that it owns or purports to own, including the
Baytown Land, all improvements thereon and all of the properties and assets
reflected in the Balance Sheet (except for personal property sold by NGO since
the date of the Balance Sheet in the Ordinary Course of Business of NGO).

         Section 3.13     ACCOUNTS RECEIVABLE.  All accounts receivable of NGO
that are reflected on the Balance Sheet or arising since the date of the
Balance Sheet (subject to the reserve for bad debts reflected on the Balance
Sheet) represent valid obligations and have been collected or are collectible
and are subject to no defenses, set-offs or counterclaims that are not
reflected on the Balance Sheet.  Set forth on Schedule 3.13 is a list of all
accounts receivable of NGO as of the date indicated on such Schedule, showing
separately those accounts receivable that as of such date have been outstanding
(i) 1 to 29 days, (ii) 30 to 59 days, (iii) 60 to 89 days, and (iv) 90 days or
more.

         Section 3.14     INVENTORY.  The inventory of NGO consists of odorants
for natural gas and liquefied petroleum gas, products used in the chemical
industry and constituent chemicals for the production of such odorants and
products.  Such inventory is salable in the Ordinary Course of Business of NGO,
except for items which have been written off or written down to net realizable
value thereof in the Balance Sheet.

         Section 3.15     ABSENCE OF CERTAIN CHANGES.  Except as disclosed on
Schedule 3.15, since the date of the Balance Sheet, (i) there has not been any
material adverse change in, or any event or condition that might reasonably be
expected to result in any material adverse change in, the business, operations,
properties, prospects, assets or condition (financial or otherwise) of NGO,
(ii) the business of NGO has been conducted only in the Ordinary Course of
Business of NGO, (iii) NGO has not incurred any material liability, engaged in
any material transaction or entered into any material agreement outside the
Ordinary Course of Business of NGO, (iv) NGO has not suffered any material
loss, damage, destruction or other casualty to, or condemnation of, any of the
Assets (whether or not covered by insurance), and (v) NGO has not taken any of
the actions set forth in Section 5.2 except as permitted thereunder.

         Section 3.16     EMPLOYEE BENEFITS.

         (a)     Schedule 3.16 contains a true and complete list of each bonus,
deferred compensation, incentive compensation, stock purchase, stock option,
employment, consulting, severance or termination pay, hospitalization or other
medical, life or other insurance, supplemental unemployment benefits,
profit-sharing, pension or retirement plan, program, agreement or arrangement,
and each other "employee benefit plan" (within the meaning of section 3(2) of
ERISA), program, agreement or arrangement, whether formal or informal, written
or oral, and whether legally binding or not, sponsored, maintained or
contributed to, or required to be contributed to, by H&P or NGO or by any trade
or business, whether or not incorporated, that, together with H&P or NGO, would





                                       19
<PAGE>   27




be deemed a "single employer" within the meaning of section 4001(b)(1) of
ERISA, a "controlled group" within the meaning of section 414(b) of the Code,
"trades or businesses under common control" within the meaning of section
414(c) of the Code, or an "affiliated service group" within the meaning of
section 414(m) of the Code (an "ERISA Affiliate") within the last six years,
for the benefit of any employee, former employee, consultant, officer or
director of NGO (the "Plans").  Schedule 3.16 includes and identifies each of
the Plans that is an "employee welfare benefit plan", as defined in Section
3(1) of ERISA ("Welfare Plans"), or "employee pension benefit plan", as defined
in Section 3(2) of ERISA ("Pension Plans", and together with Welfare Plans,
hereinafter referred to collectively as "ERISA Plans").  Except as set forth in
Schedule 3.16, neither H&P, NGO nor any ERISA Affiliate has any plan or
commitment, whether legally binding or not, to create any additional Plan or to
modify or change any existing Plan that would affect any employee or terminated
employee of NGO or any ERISA Affiliate.  Except as set forth in Schedule 3.16,
there has been no merger, consolidation, or transfer of assets or liabilities
(including any spin-off, split up or split off) with respect to any of the
ERISA Plans.

         (b)     Except as set forth in Schedule 3.16, with respect to each of
the Plans sponsored by H&P, NGO or any ERISA Affiliate, H&P, NGO or any such
ERISA Affiliate has the right, respectively, to alter, amend, suspend or
terminate any such Plan.

         (c)     With respect to each of the Plans, NGO or H&P has heretofore
delivered to Occidental true and complete copies of the following documents:

                          (i)     a copy of the Plan (including all adopted and
                 pending amendments thereto), including any material documents
                 necessary or appropriate for the proper operation and
                 administration of the Plan;

                          (ii)    a copy of the annual report, if required
                 under ERISA or any other Applicable Law, with respect to each
                 such Plan for the last three most recently completed plan
                 years;

                          (iii)   a copy of the actuarial report, if required
                 under ERISA or any other Applicable Law, with respect to each
                 such Plan for the last three completed plan years;

                          (iv)    a copy of the most recent Summary Plan
                 Description ("SPD"), together with all Summaries of Material
                 Modification issued with respect to such SPD, if required
                 under ERISA with respect to each such Plan, and all other
                 material employee communications relating to each such Plan;

                          (v)     if any of the Plans is funded through a trust
                 or any other funding vehicle, a copy of the trust or other
                 funding agreement (including





                                       20
<PAGE>   28




                 all adopted and pending amendments thereto) and the latest
                 financial statements thereof;

                          (vi)    all contracts relating to the Plans with
                 respect to which H&P, NGO or any ERISA Affiliate may have any
                 liability, including insurance contracts, investment
                 management agreements, subscription and participation
                 agreements and recordkeeping or other servicing or
                 administrative agreements; and

                          (vii)   the most recent determination letter received
                 from the Internal Revenue Service with respect to each Plan
                 that is intended to be qualified under section 401 of the
                 Code.

         (d)     To the extent necessary or appropriate for the proper
operation and administration of each of the Plans, the participant and
beneficiary records with respect to each of such Plans accurately state the
history of each participant and beneficiary in connection with each of the
respective Plans and accurately state the benefits earned and owed to each
person under such Plans.

         (e)     Each of the Plans is, and has always been, operated in all
material respects in accordance with all Applicable Laws, and H&P, each of
H&P's designees and all fiduciaries (within the meaning of section 3(21) of
ERISA) of all of such Plans, and, to the Knowledge of H&P, all other persons
who participate in the operation of such Plans, have always acted in accordance
with the provisions of all Applicable Laws, the Plan documents and written
descriptions of the Plans.  Each of the Plans intended to be "qualified" within
the meaning of 401(a) of the Code is so qualified and has received a currently
applicable favorable determination letter issued under Revenue Procedure 93-39
by the Internal Revenue Service to that effect.

         (f)     No liability under Title IV of ERISA has been incurred,
directly or indirectly, by H&P, NGO or any ERISA Affiliate since the effective
date of ERISA that has not been satisfied in full, and no condition exists that
presents a material risk to NGO or any ERISA Affiliate of incurring a liability
under such Title, other than a liability for premiums due the Pension Benefit
Guaranty Corporation ("PBGC"), which payments have been or will be made when
due.  To the extent that this representation applies to section 4064, 4069 or
4204 of Title IV of ERISA, it is made not only with respect to ERISA Plans but
also with respect to any employee benefit plan, program, agreement or
arrangement subject to Title IV of ERISA to which NGO or any ERISA Affiliate
made, or was required to make, contributions during the five year period ending
on the last day of H&P's most recent fiscal year.

         (g)     The PBGC has not instituted any Proceedings to terminate any
of the ERISA Plans, and no condition exists that presents a material risk that
any such Proceedings will be instituted.





                                       21
<PAGE>   29




         (h)     No reportable event within the meaning of Section 4043 of
ERISA, or prohibited transaction within the meaning of Section 406 of ERISA,
has occurred with respect to any Plan.

         (i)     Neither NGO, any ERISA Affiliate, any of the ERISA Plans or
any trust created thereunder nor any trustee or administrator thereof has
engaged in any transaction or has taken or failed to take any action in
connection with which NGO, any ERISA Affiliate, any of the ERISA Plans, any
such trust, any trustee or administrator thereof, or any party dealing with the
ERISA Plans or any such trust could be subject to any liability, fine, penalty,
tax or related charge under section 409, section 502(c), (i) or (l), or section
4071 of ERISA or Chapter 43 of the Code, or the imposition of a lien pursuant
to section 401(a)(29) or 412(n) of the Code.  Each Welfare Plan of H&P, NGO or
any ERISA Affiliate that is subject to section 1862(b)(1) of the Social
Security Act, as amended, has been operated in compliance with the secondary
payor requirements of such section.

         (j)     The current value of the assets of each of the Plans that is
subject to Title IV of ERISA exceeds the present value of the accrued benefits
under each such Plan, based upon the actuarial assumptions used for funding
purposes in the most recent actuarial report prepared for such Plan.  Full
payment has been made, or will be made in accordance with section 404(a)(6) of
the Code, of all amounts which NGO or any ERISA Affiliate is required to pay
under the terms of each of the ERISA Plans and section 412 of the Code, and all
such amounts properly accrued through the Closing with respect to the current
plan year thereof will be paid by NGO or H&P on or prior to the Closing or will
be properly recorded on the Balance Sheet; and none of the ERISA Plans or any
trust established thereunder has incurred any "accumulated funding deficiency"
(as defined in section 302 of ERISA and section 412 of the Code), whether or
not waived, as of the last day of the most recent fiscal year of each of the
ERISA Plans ended prior to the date of this Agreement.

         (k)     Except as set forth on Schedule 3.16, no assets of any of the
Plans are invested, directly or indirectly, in any obligation of, or security
or other instrument issued by, H&P, NGO or, with respect to the ERISA Plans,
any ERISA Affiliate, and no assets of any of the Plans are invested, directly
or indirectly, in real or personal property used by H&P, NGO or, with respect
to the ERISA Plans, any ERISA Affiliate.  There is sufficient liquidity of
assets in each of the funded Plans to promptly pay for the benefits earned and
other liabilities owed under such Plan.  With respect to each of the Plans, no
insurance contract, annuity contract, or other agreement or arrangement with
any financial or other organization would impose any penalty, discount or other
reduction on account of the withdrawal of assets from such organization or the
change in the investment of such assets.

         (l)     Except as set forth in Schedule 3.16, no Plan is a
"multiemployer plan" as such term is defined in section 3(37) of ERISA.  No
Plan is a plan maintained by more than one employer (a so-called "multiple
employer plan") for purposes of section 413(c) of the Code.





                                       22
<PAGE>   30




         (m)     No amounts payable under the Plans or any other agreement or
arrangement to which NGO is a party will, as a result of the transactions
contemplated by this Agreement, fail to be deductible for federal income tax
purposes by virtue of section 280G of the Code.

         (n)     No "leased employee", as that term is defined in section
414(n) of the Code, performs services for NGO.

         (o)     Except as set forth in Schedule 3.16, no Plan provides
benefits, including death or medical benefits (whether or not insured), with
respect to current or former employees of NGO after retirement or other
termination of service other than (i) coverage mandated by applicable law, (ii)
death benefits or retirement benefits under any "employee pension plan", as
that term is defined in section 3(2) of ERISA, (iii) deferred compensation
benefits accrued as liabilities on the books of NGO or an ERISA Affiliate, or
(iv) benefits, the full cost of which is borne by the current or former
employee (or his beneficiary).

         (p)     With respect to each Plan that is funded wholly or partially
through an insurance policy, there will be no liability of NGO or an ERISA
Affiliate, as of the Closing Date, under any such insurance policy or ancillary
agreement with respect to such insurance policy in the nature of a retroactive
rate adjustment, loss sharing arrangement or other actual or contingent
liability arising wholly or partially out of events occurring prior to the
Closing Date.

         (q)     Except as described in Schedule 3.16, there is, and has been,
no actual, and, to the Knowledge of H&P, no anticipated, threatened or
expected, litigation or arbitration concerning or involving any of the Plans.
No complaints to or by any  Governmental Body have been filed, or, to the
Knowledge of H&P, are threatened or expected, with respect to any of the Plans.
No claims have been made, or, to the Knowledge of H&P, are expected, with
respect to any bond or any fiduciary or other similar insurance with regard to
the actions of any Person in connection with any of the ERISA Plans or other
funded Plans, nor has there been, nor is there, to the Knowledge of H&P,
expected, any notice to any insurer under any such bond or policy with regard
to any of such Plans.  No application for any bond or fiduciary liability or
similar insurance policy has been issued subject to any qualification,
condition or exclusion.

         (r)     Except as set forth in Schedule 3.16, the consummation of the
transactions contemplated by this Agreement will not (i) entitle any current or
former employee or officer of H&P or any of its subsidiaries to severance pay,
unemployment compensation or any other similar payment, except as expressly
provided in this Agreement, (ii) accelerate the time of payment or vesting, or
increase the amount, of any compensation due to any such employee or officer,
(iii) result in any employment-related expenses or liabilities, the full cost
of which will not be paid by H&P, or (iv) result in any prohibited





                                       23
<PAGE>   31




transaction described in Section 406 of ERISA or Section 4975 of the Code for
which an exemption is not available.

         Section 3.17     LABOR RELATIONS.

         (a)     Except as set forth on Schedule 3.17, (i) there is no labor
strike, dispute, slowdown, work stoppage or lockout actually pending or, to the
Knowledge (which term, for purposes of this Section 3.17, includes any Person
for whom NGO is or may be responsible) of H&P, threatened against or affecting
NGO and, during the past five years, there has not been any such action, (ii),
to the Knowledge of H&P, there are no union claims to represent the employees
of NGO, (iii) NGO is not a party to, or bound by, any collective bargaining or
similar agreement with any labor organization, or work rules or practices
agreed to with any labor organization or employee association applicable to
employees of NGO, (iv) none of the employees of NGO are represented by any
labor organization, and H&P has no knowledge of any current union organizing
activities among the employees of NGO, nor does any question concerning
representation exist concerning such employees, (v) there are no written
personnel policies, rules or procedures applicable to employees of NGO, other
than those which have heretofore been delivered to Occidental, (vi) NGO has at
all times been in material compliance with all Applicable Laws respecting
employment and employment practices, terms and conditions of employment, wages,
hours of work and occupational safety and health, and is not engaged in any
unfair labor practices as defined in the National Labor Relations Act, as
revised, or other applicable law, ordinance or regulation, (vii) there is no
unfair labor practice charge or complaint against NGO pending, or, to the
Knowledge of H&P, threatened, before the National Labor Relations Board or any
similar state or foreign agency, (viii) there is no grievance or arbitration
proceeding arising out of any collective bargaining agreement or other
grievance procedure relating to NGO, (ix), to the Knowledge of H&P, no charges
with respect to, or relating to, NGO are pending before the Equal Employment
Opportunity Commission or any other corresponding state agency, (x), to the
Knowledge of H&P, no federal, state, local or foreign agency responsible for
the enforcement of labor or employment laws intends to conduct an investigation
with respect to, or relating to, NGO, and no such investigation is in progress,
(xi) there are no threatened or pending wage and hour claims filed against NGO
with the United States Department of Labor or any corresponding state agency,
(xii) neither the Occupational Safety and Health Administration nor any
corresponding state agency has threatened to file any citation, and there are
no pending citations relating to NGO, (xiii) there is no pending investigation
of, or complaint pending against, NGO by the Office of Federal Contract
Compliance Programs or any corresponding state agency, and (xiv) there are no
complaints, controversies, lawsuits or other proceedings pending against NGO
brought on behalf of any applicant for employment or classes of any such
applicants alleging (A) any breach of any express or implied contract of
employment, any law or regulation governing employment or the termination
thereof, or (B) other discriminatory, wrongful or tortious conduct in
connection with the employment relationship.





                                       24
<PAGE>   32





         (b)     Since the enactment of the Worker Adjustment and Retraining
Notification Act of 1988, NGO never has employed at any one time 100 or more
employees on a full or part-time basis.

         Section 3.18     LEGAL PROCEEDINGS; ORDERS.

         (a)     Except as set forth on Schedule 3.18 , there is no Proceeding
pending, or, to the Knowledge of H&P, threatened, by, against or involving NGO
or any of the Assets.

         (b)     Except as set forth on Schedule  3.18, there is no Order to
which NGO or any of the Assets is subject.

         (c)     There is no Proceeding pending, or, to the Knowledge of H&P,
threatened, by, against or involving H&P, any of its Affiliates or any of the
Assets and that challenges, or that may have the effect of preventing,
restraining, prohibiting, delaying, making illegal, obtaining damages or other
relief in connection with, or otherwise interfering with, this Agreement or any
of the transactions contemplated hereby.

         Section 3.19     COMPLIANCE WITH LAWS.  Except as disclosed on
Schedule 3.19, (i) H&P and NGO have complied in all material respects with all
Applicable Laws and the Assets have been operated in all material respects in
compliance with all Applicable Laws, (ii) neither H&P nor NGO has received any
written notice of non-compliance from any Governmental Body, which has not been
dismissed, or with which any of them has not fully complied or that any of the
Assets have not been operated in such compliance, and (iii) neither H&P nor NGO
is charged or, to the Knowledge of H&P, threatened with, or under investigation
with respect to, any violation of any Applicable Law relating to any aspect of
the business of NGO.  Set forth on Schedule 3.19 is an accurate and complete
list of each such notice.  There has been no operator of any of the Assets
other than H&P and NGO.

         Section 3.20     PERMITS.  Set forth in Part I of Schedule 3.20 is a
complete and accurate list, and H&P has delivered to Occidental true and
complete copies, of each Permit held by NGO.   Except as disclosed in Part II
of Schedule 3.20, (i) NGO holds all Permits necessary or required for the
conduct of the business of NGO as presently conducted, (ii) each of such
Permits is in full force and effect, and (iii) NGO is in compliance in all
material respects with all of the obligations of NGO with respect thereto.
Except as disclosed in Part II of Schedule 3.20, no notice has been issued by
any Governmental Body and no Proceeding is pending, or, to the Knowledge of
H&P, threatened, with respect to any alleged failure by NGO to have any such
Permit or to be in compliance therewith.  No event has occurred and is
continuing which permits, or after notice or lapse of time or both would
permit, any modification or termination of any such Permit.





                                       25
<PAGE>   33





         Section 3.21     CONTRACTS; NO DEFAULTS.

         (a)     Part I of Schedule 3.21 is a complete and accurate list, and
H&P has made available to Occidental true and complete copies, of each of the
following Applicable Contracts:

                 (i)      Each  Applicable Contract for, or relating to, any
         borrowing of money, or any guaranty of any liability or obligation, by
         NGO;

                 (ii)     Each Applicable Contract with a term in excess of one
         year that involves the performance of services or the delivery of
         goods or materials by NGO of an aggregate amount or value in excess of
         $50,000;

                 (iii)    Each Applicable Contract with a term in excess of one
         year that involves the performance of services or the delivery of
         goods or materials to NGO of an aggregate amount or value in excess of
         $50,000;

                 (iv)     Each Applicable Contract that was not entered into in
         the Ordinary Course of Business of NGO and that involves aggregate
         expenditures or receipts of NGO in excess of $50,000;

                 (v)      Each lease, rental or occupancy agreement, license,
         installment or conditional sale agreement, and each other Applicable
         Contract, involving or affecting the ownership of, leasing of, title
         to, use of, or any leasehold or other interest in, or arising out of,
         or relating to, the acquisition or disposition of, any Asset (other
         than personal property leases and installment and conditional sales
         agreements having aggregate payments of less than $50,000 and with
         terms of less than one year);

                 (vi)     Each Applicable Contract, including any employment,
         compensation or severance arrangements, with any current director,
         officer or employee of NGO;

                 (vii)    Each Applicable Contract with any consultant or
         advisor of NGO that involves aggregate expenditures of NGO in excess
         of $50,000;

                 (viii)   Each Applicable Contract to which H&P or any
         Affiliate of H&P is a party;

                 (ix)     Each Applicable Contract containing covenants that in
         any way purport to restrict the business activity of NGO or limit the
         freedom of NGO to engage in any line of business or to compete with
         any Person;

                 (x)      Each Applicable Contract involving a sharing of
         profits, losses, costs or liabilities by NGO with any other Person;





                                       26
<PAGE>   34





                 (xi)     Each Applicable Contract relating to the treatment,
         storage, Release, recycling, disposal or Cleanup of Hazardous
         Materials;

                 (xii)    Each Applicable Contract with any Governmental Body
         that is binding on, or restricts the actions of, NGO;

                 (xiii)   Each Applicable Contract involving hedges, swaps,
         futures, options or other derivatives, or similar arrangements;

                 (xiv)    Each Applicable Contract in the nature of a
         settlement or a conciliation agreement arising out of any pending
         claim by any Person other than NGO;

                 (xv)     Each licensing agreement or other Applicable Contract
         with respect to patents, trademarks, copyrights or other intellectual
         property, including agreements with current or former employees,
         consultants or contractors regarding the appropriation or the
         non-disclosure of any trade secrets or intellectual property of NGO;

                 (xvi)    Each collective bargaining agreement and other
         Applicable Contract to, or with, any labor union or other employee
         representative of a group of employees that covers any of the
         Employees;

                  (xvii)  Each Applicable Contract providing for payments to or
         by any Person based on sales, purchases or profits, other than direct
         payments for goods;

                 (xviii)          Each power of attorney that is currently
         effective and outstanding;

                 (xix)    Each Applicable Contract calling for capital
         expenditures in excess of $50,000; and

                 (xx)     Each amendment, supplement and modification (whether
         oral or written) in respect of any of the foregoing.

         (b)     Except as set forth in Part II of Schedule 3.21, (i) each
Applicable Contract identified or required to be identified on Schedule 3.21 is
in full force and effect and is valid and enforceable in accordance with its
terms, and (ii) no notices of termination or cancellation thereof have been
given or received by H&P or NGO.  Neither NGO nor, to the Knowledge of H&P, any
other party to any such Applicable Contract is in breach of, or default under,
any such Applicable Contract, and no event has occurred that (after notice or
lapse of time or both) would (A) become a breach of, or a default under, or
would permit modification, cancellation, acceleration or termination of, any
such Applicable Contract, or (B) result in the creation of any Encumbrance
upon, or any Person obtaining any right to acquire, any of the Assets or any
rights of NGO under





                                       27
<PAGE>   35




any such Applicable Contract.  There are no material unresolved disputes
involving NGO under any Applicable Contract.

         Section 3.22     DISCHARGE OF OBLIGATIONS.  Except as set forth on
Schedule 3.22, since March 31, 1996, NGO has not discharged any liabilities or
obligations involving the payment of an amount in excess of the amount
reflected for such liability or obligation in the Balance Sheet.

         Section 3.23     MATERIAL PERSONAL PROPERTY.  All material
improvements, fixtures and equipment owned in whole or in part by NGO are being
maintained in a state adequate to conduct normal operations in the Ordinary
Course of Business of NGO.

         Section 3.24     REAL PROPERTY.  Set forth on Schedule 3.24 is a list
of all interests in real property presently, or, to the Knowledge of H&P,
formerly, owned or leased by NGO, and specifying the location of each such
property.  The present use of all such owned or leased real property, and, to
the Knowledge of H&P, such formerly owned or leased real property, conforms in
all material respects to Applicable Law, and all necessary occupancy and other
certificates and Permits for the occupancy and lawful use thereof have been
issued and are presently in full force and effect.  With respect to the Baytown
Land, there are no adverse or other parties in possession of the Baytown Land.
Except as set forth on Schedule 3.24, with respect to the Baytown Land, there
are no pending, or, to the Knowledge of H&P, threatened, condemnation, eminent
domain or similar Proceedings, and there is no pending, or, to the Knowledge of
H&P, threatened, litigation affecting the Baytown Land; to the Knowledge of H&P
and except as set forth on Schedule 3.24, there are no Encumbrances to title
evidencing environmental contamination on the Baytown Land; and all water,
sewer, gas, electric, telephone, drainage and other utility equipment,
facilities and services required by Law or necessary for the operation of the
business of NGO are installed and connected pursuant to valid Permits, and no
notice has been received by H&P or any of its Affiliates regarding the
termination or material impairment of such service. The Baytown Land has access
to and from a public right of way.  No notice has been received by H&P or any
of its Affiliates relating to any termination or impairment of such access.

         Section 3.25     BANKING ARRANGEMENTS OF NGO.  Schedule 3.25 lists (i)
the name of each bank or other financial institution in which NGO has an
account of any type or a safe deposit box and the number of each such account
or safe deposit box, and (ii) the names of all Persons having authorization to
draw thereon or having access thereto.

         Section 3.26     INSURANCE.

         (a)     H&P or NGO has given proper and timely notice to NGO's
insurers with respect to all known claims which could potentially exceed NGO's
retention or deductible levels under applicable insurance policies and which,
to the Knowledge of H&P, are covered by such policies.





                                       28
<PAGE>   36





         (b)     Schedule 3.26.1 sets forth a list of all primary and excess
occurrence-based policies covering NGO over the ten years immediately preceding
that date of this Agreement.  H&P has made available to Occidental a true and
correct copy of (i) each general liability and products liability policy listed
on Schedule 3.26.1 which currently insures NGO or which covers NGO-related
claims which are outstanding from prior policy years, and (ii) each property
insurance and boiler & machinery insurance policy listed on Schedule 3.26.1
covering NGO over the two years immediately preceding the date of this
Agreement.

         (c)     Schedule 3.26.2 sets forth a list of all claims-made policies
under which H&P or NGO has tendered to NGO's insurers, or given notice to such
insurers of, a claim and which is outstanding.  H&P has made available to
Occidental a true and correct copy of each of such policies.

         (d)     Schedule 3.26.3 sets forth a list of all insurance-related
indemnification and deductible reimbursement agreements between H&P and the
insurers named thereon and providing liability coverage to, among others, NGO.
H&P has made available to Occidental a true and correct copy of each of such
agreements.

         (e)     Schedule 3.26.4 sets forth a list of each certificate of
insurance which has been issued to third parties on behalf of NGO by any of its
insurers or any of their agents and pertaining to policies in effect.

         (f)     Schedule 3.26.5 sets forth a list of each surety bond
outstanding on behalf of NGO.

         Section 3.27     ENVIRONMENTAL MATTERS.  Except as set forth in
Schedule 3.27:

         (a)     The Facilities and the Assets are operated, and any Hazardous
Activity by or on behalf of NGO is conducted, in substantial compliance with
all Environmental Laws.

         (b)     The Facilities and the Assets have been operated, and any
Hazardous Activity by or on behalf of NGO has been conducted, in substantial
compliance with applicable Environmental Laws.

         (c)     None of H&P, NGO or any Representative of H&P or NGO, or any
other Person acting on behalf of any thereof, has received any notice, Order,
demand, correspondence or other communication from any Governmental Body or any
other Person alleging (i) any actual or potential violation or failure to
comply with any Environmental Law by NGO or with respect to the Facilities or
the Assets, or (ii) any actual or potential obligation, responsibility or
liability to address, bear the cost of, or pay damages in lieu of addressing,
any Environmental Liabilities with respect to the Facilities, the Assets or any
property at, to or from which Hazardous Materials were distributed, generated,
handled, imported, managed, manufactured, processed, produced,





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<PAGE>   37




refined, Released, stored, transferred, transported, recycled, treated,
disposed or used by or on behalf of NGO, H&P with respect to the Facilities or
the Assets, or any other Person for whose conduct NGO is or may be held
responsible.

         (d)     None of H&P, NGO or any Representative of H&P or NGO, or any
other Person acting on behalf of any thereof, has Released, or caused or
permitted a Threatened Release of, a "reportable quantity," as defined by
Section 102 of CERCLA, 42 U.S.C. Section  9602, or any state or local analogue
thereof, or any regulations of the United States Environmental Protection
Agency ("EPA") or the Texas Natural Resource Conservation Commission ("TNRCC")
thereunder, of any Hazardous Materials at or from the Facilities or the Assets
or with respect to NGO's business operations.

         (e)     None of H&P, NGO or any Representative of H&P or NGO, or any
other Person acting on behalf of any thereof, has treated, stored, Released,
recycled, disposed of or performed a Cleanup of, or arranged the treatment,
storage, Release, recycling, disposal or Cleanup of, any Hazardous Materials at
or from the Facilities or the Assets or with respect to NGO's business
operations, except in compliance with Environmental Law and Permits.

         (f)     None of H&P, NGO or any Representative of H&P or NGO, or any
other Person acting on behalf of any thereof, has Released or disposed of
"hazardous waste," as defined by Section 1004(5) of the Solid Waste Disposal
Act, 42 U.S.C. Section  6903(5), or any state or local analogue thereof, or any
regulations of the EPA or TNRCC thereunder, into the Environment at or from the
Facilities.

         (g)     There are no polychlorinated biphenyls in any of the Assets or
at the Facilities.

         (h)     There are no friable asbestos-containing materials at the
Facilities.

         (i)     There have been and are no underground storage tanks located
at the Facilities, and neither H&P nor NGO has owned or operated any
underground storage tanks at the Facilities or with respect to NGO's business
operations.

         (j)     The Facilities have not been operated or used as a landfill,
landfarm, dump, or land disposal site for the disposal or deposit of Hazardous
Materials or "solid waste" (as defined by Section 1004(27) of the Solid Waste
Disposal Act, 42 U.S.C. Section  6903(27)).

         (k)     NGO has not owned, leased or operated any real property or
facility for any disposal, generation, handling, management, manufacturing,
processing, production, recycling, Release, Threatened Release, storage,
treatment or use of any Hazardous Materials other than on the Baytown Land.





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<PAGE>   38




         Section 3.28     INTELLECTUAL PROPERTY.  Section 3.28 contains a
complete and accurate list of all Intellectual Property Rights.  NGO either
owns or has valid licenses to use all Intellectual Property Rights, subject to
the limitations set forth in the agreements governing such use.  There are no
limitations set forth in any of such agreements which, upon consummation of the
transactions contemplated by this Agreement, will alter or impair any rights of
NGO under any such agreement, breach any such agreement or require payment of
any sums thereunder.  NGO is in compliance with each such license and
agreement, and there are no pending, or, to the Knowledge of H&P, threatened,
Proceedings, disputes or disagreements with respect to any such Intellectual
Property Rights.

         Section 3.29     SURVEY.  H&P has delivered the Survey to Occidental.

         Section 3.30     FOREIGN ASSETS.  Except as set forth in Schedule
3.30, NGO does not own, lease or use any property located outside of the United
States, including securities, investments in, claims against, or receivables
from, any Persons having their property or business principally so located.

         Section 3.31     CLAIMS BY DIRECTORS AND OFFICERS, ETC. OF NGO.  There
are no outstanding claims by any present or former director, officer, employee
or agent of NGO which are indemnifiable by NGO.

         Section 3.32     BROKERS OR FINDERS.  Neither H&P nor any of its
Affiliates has (i) retained any financial advisor, broker, agent or finder, or
(ii) paid, or agreed to pay, any financial advisor, broker, agent or finder on
account of this Agreement or any of the transactions contemplated hereby,
except that Smith Barney Inc. has been retained as H&P's financial advisor in
connection with the transactions contemplated hereby.

         Section 3.33     INVESTMENT INTENT.  H&P understands and acknowledges
that the shares of the Occidental Common Stock issuable pursuant to the
provisions of this Agreement have not been registered under the Securities Act
or under the securities laws of any State.  H&P (i) has such business
experience that it is capable of evaluating the merits and risks of its
investment in such shares, and (ii) is acquiring such shares for its own
account for the purpose of investment and not with a view to, or for sale or
other disposition in connection with, any distribution thereof, except (a) in
any offering covered by a registration statement under the Securities Act, or
(b) pursuant to an applicable exemption under the Securities Act.

         Section 3.34     REGULATED INDUSTRY.  Neither H&P nor NGO is, with
respect to the business of NGO, subject to regulation under the PUHCA, the
Investment Company Act of 1940, as amended, or the Interstate Commerce Act, nor
is either such Person subject to regulation pursuant to any rules or
regulations promulgated thereunder.  Neither H&P nor NGO is, with respect to
such business, a "holding company", or a "subsidiary company" of a "holding
company", or an "affiliate" of a "holding company"





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<PAGE>   39




or of a "subsidiary company" of a "holding company", or a "public utility",
within the meaning of the PUHCA and the rules and regulations promulgated
thereunder.

         Section 3.35  LIMITATION ON REPRESENTATIONS AND WARRANTIES BY H&P.

         (a)     Except as and to the extent expressly set forth in this
Agreement, included on any Schedule or in any Exhibit or included in any
writing delivered by H&P to Occidental currently herewith or subsequent hereto
expressly pursuant to the provisions of this Agreement, H&P makes no other
representation or warranty and disclaims all liability and responsibility for
any representation, warranty, statement or information (financial or otherwise)
made or communicated (orally or in writing) to Occidental or any of its
Affiliates or Representatives (including any opinion, information, projection,
financial statement, forecast or advice that may have been provided to
Occidental by any Representative of H&P or of any Affiliate thereof).  In
particular, H&P makes no representation or warranty to Occidental with respect
to any information set forth in the Confidential Memorandum.  With respect to
any such projection or forecast, Occidental acknowledges that (i) there are
uncertainties inherent in attempting to make such projections and forecasts,
(ii) Occidental is familiar with such uncertainties, (iii) it is taking full
responsibility for making its own evaluation of the adequacy and accuracy of
all such projections and forecasts, and (iv) it shall have no claim against H&P
with respect thereto.

         (b)     H&P makes no representation or warranty to Occidental
regarding the probable success or profitability of NGO.

                                   ARTICLE IV

                  REPRESENTATIONS AND WARRANTIES OF OCCIDENTAL

         Occidental represents and warrants to H&P that:

         Section 4.1      ORGANIZATION OF OCCIDENTAL AND THE COMPANY.
Occidental and the Company are corporations duly incorporated, validly existing
and in good standing under the laws of the States of  Delaware and Oklahoma,
respectively.

         Section 4.2      AUTHORITY RELATIVE TO THIS AGREEMENT AND THE RELATED
DOCUMENTS.  Occidental has all requisite corporate power and authority (i) to
execute and deliver this Agreement and each of the Related Documents to which
it is a party, (ii) to consummate the transactions contemplated hereby and
thereby, and (iii) to perform the obligations of Occidental hereunder and
thereunder, including the execution, delivery and performance of all agreements
and documents necessary to effectuate the transactions contemplated hereby and
thereby.  The Company has all requisite corporate power and authority (A) to
execute and deliver this Agreement, (B) to consummate the transactions
contemplated hereby, and (C) to perform the obligations of the Company
hereunder, including the execution, delivery and performance of all agreements
and documents





                                       32
<PAGE>   40




necessary to effectuate the transactions contemplated hereby.  The execution
and delivery by Occidental of, and the performance by Occidental of its
obligations under, this Agreement and each of the Related Documents to which it
is a party have been duly authorized by the Board of Directors of Occidental
(with the exact number of shares of the Occidental Common Stock issuable
pursuant to the provisions of this Agreement and certain other matters to be
determined by a pricing committee thereof), and no other corporate proceedings
on the part of Occidental are necessary to authorize the execution, delivery
and performance by Occidental of this Agreement and each of such Related
Documents and the consummation by Occidental of the transactions contemplated
hereby and thereby.  The execution and delivery by the Company of, and the
performance by the Company of its obligations under, this Agreement have been
duly authorized by all requisite corporate action on the part of the Company,
and no other corporate proceedings on the part of the Company or its sole
shareholder are necessary to authorize the execution, delivery and performance
by the Company of this Agreement and the consummation by the Company of the
transactions contemplated hereby.  This Agreement has been duly executed and
delivered by Occidental and the Company and constitutes (and (1), in the case
of Occidental, each of the Related Documents to which Occidental is a party,
and (2), in the case of Occidental and the Company, each other agreement,
instrument or document executed or to be executed by Occidental or the Company
in connection with the transactions contemplated hereby or thereby, has been,
or when executed will be, duly executed and delivered by Occidental or the
Company, as the case may be, and constitutes, or when so executed and delivered
will constitute) a valid and legally binding obligation of Occidental or the
Company enforceable against Occidental or the Company, as the case may be, in
accordance with its terms, except that such enforceability may be limited by
applicable bankruptcy, insolvency, reorganization, moratorium or similar laws
affecting creditors' rights generally and equitable principles (whether applied
in a court of law or equity).

         Section 4.3      NONCONTRAVENTION.  Except as set forth on Schedule
4.3, (i) the execution, delivery and performance by (A) Occidental of this
Agreement and each of the Related Documents to which Occidental is a party, and
(B) the Company of this Agreement, and (ii) the consummation by (1) Occidental
of the transactions contemplated by this Agreement or each of such Related
Documents, and (2) the Company of the transactions contemplated by this
Agreement do not and will not (I) contravene, conflict with, or result in a
breach or violation of, any of the terms, provisions or conditions of, (a) the
charter or by-laws of Occidental or the Company, (b) any resolution adopted by
the Board of Directors or the stockholders of Occidental or the Company, or (c)
any Order or Permit to which Occidental or the Company may be subject, (II)
contravene, conflict with, or result in a breach or violation of, any of the
terms, provisions or conditions of, or constitute (with or without the giving
of notice or the passage of time or both) a default under, or give rise (with
or without the giving of notice or the passage of time or both) to any right of
termination, amendment, cancellation or acceleration of, or require payment
under, any bond, debenture, note, mortgage, indenture, lease or other Contract
to which Occidental or the Company is a party or by which Occidental or the
Company or any of their respective properties or assets may be bound or
affected, (III) result in the





                                       33
<PAGE>   41




imposition or creation of any Encumbrance upon, or with respect to, any of the
properties or assets owned or used by Occidental or the Company, or (IV),
assuming compliance with the matters referred to in Section 4.4, violate any
Law binding upon Occidental or the Company.

         Section 4.4      CONSENTS.  No Consent of, or declaration, filing or
registration with, any Person (including any Governmental Body) is required to
be obtained or made by Occidental or the Company in connection with (i) the
execution, delivery or performance by (A) Occidental of this Agreement or any
of the Related Documents to which Occidental is a party, or (B) the Company of
this Agreement, or (ii) the consummation by (1) Occidental of the transactions
contemplated by this Agreement or any of such Related Documents, or (2) the
Company of the transactions contemplated by this Agreement, other than (I)
compliance with the applicable requirements of the HSR Act, (II) compliance
with any applicable state securities or takeover laws, (III) filings with
federal and state securities commissions in connection with the transactions
contemplated by the Registration Agreement, and (IV) other filings with
Governmental Bodies in the Ordinary Course of Business of Occidental or the
Company that are not required to be made prior to the consummation of the
transactions contemplated by this Agreement or such Related Documents.

         Section 4.5      SHARES OF OCCIDENTAL COMMON STOCK.  As of the
Closing, the shares of the Occidental Common Stock issuable pursuant to the
provisions of this Agreement will have been duly authorized for such issuance
and, when issued as contemplated by such provisions, will be validly issued,
fully paid and non-assessable.  Such issuance of such shares is not the subject
of any preemptive rights.

         Section 4.6      SEC FILINGS.  Occidental has delivered to H&P
accurate and complete copies of (i) the Annual Report on Form 10-K of
Occidental for the fiscal year ended December 31, 1995, (ii) its Quarterly
Reports on Form 10-Q for the quarterly periods ended March 31, 1996 and June
30, 1996, (iii) its Proxy Statement for its last Annual Meeting of
Stockholders, and (iv) its Current Reports on Form 8-K as filed since January
1, 1996, in each case in the form filed by Occidental with the SEC (together,
the "Occidental Reports").  None of the Occidental Reports, including, without
limitation, any financial statements or schedules included therein, at the time
filed, contained any untrue statement of a material fact or omitted to state
any material fact required to be stated therein or necessary in order to make
the statements contained therein, in light of the circumstances under which
they were made, not misleading.  The audited consolidated financial statements
and unaudited consolidated interim financial statements of Occidental (together
the "Occidental Financial Statements") included in such reports present fairly,
in conformity in all material respects with GAAP (except as may be indicated in
the notes thereto and except that certain information and disclosure normally
included in notes to consolidated financial statements have been condensed or
omitted from the unaudited consolidated interim financial statements pursuant
to rules and regulations of the SEC, but any resultant disclosures are in
accordance with GAAP as they apply to interim reporting), the consolidated
financial position of Occidental as of the dates thereof and its consolidated





                                       34
<PAGE>   42




results of operations and cash flows for the periods then ended (subject to
normal year-end audit adjustments in the case of any unaudited interim
financial statements).

         Section 4.7      LEGAL PROCEEDINGS.  There is no Proceeding pending,
or, to the knowledge of Occidental, threatened, by, against or involving
Occidental or any of its Affiliates and that challenges, or that may have the
effect of preventing, restraining, prohibiting, delaying, making illegal,
obtaining damages or other relief in connection with, or otherwise interfering
with, this Agreement or any of the transactions contemplated hereby.

         Section 4.8      BROKERS OR FINDERS.  Neither Occidental nor any of
its Affiliates has (i) retained any financial advisor, broker, agent or finder,
or (ii) paid, or agreed to pay, any financial advisor, broker, agent or finder
on account of this Agreement or any of the transactions contemplated hereby.

         Section 4.9      INVESTMENT INTENT.  Occidental is acquiring the
shares of the Surviving Corporation for its own account for the purpose of
investment and not with a view to, or for sale or other disposition in
connection with, any distribution thereof, except (a) in any offering covered
by a registration statement under the Securities Act, or (b) pursuant to an
applicable exemption under the Securities Act.

         Section 4.10  LIMITATION ON REPRESENTATIONS AND WARRANTIES BY
OCCIDENTAL.

         (a)     Except as and to the extent expressly set forth in this
Agreement, included on any Schedule or in any Exhibit or included in any
writing delivered by Occidental to H&P currently herewith or subsequent hereto
expressly pursuant to the provisions of this Agreement, Occidental makes no
other representation or warranty and disclaims all liability and responsibility
for any representation, warranty, statement or information (financial or
otherwise) made or communicated (orally or in writing) to H&P or any of its
Affiliates or Representatives (including any opinion, information, projection,
financial statement, forecast or advice that may have been provided to H&P by
any Representative of Occidental or of any Affiliate thereof). With respect to
any such projection or forecast, H&P acknowledges that (i) there are
uncertainties inherent in attempting to make such projections and forecasts,
(ii) H&P is familiar with such uncertainties, (iii) it is taking full
responsibility for making its own evaluation of the adequacy and accuracy of
all such projections and forecasts, and (iv) it shall have no claim against
Occidental with respect thereto.

         (b)     Occidental makes no representation or warranty to H&P
regarding the probable success or profitability of Occidental.





                                       35
<PAGE>   43




                                   ARTICLE V

                         CONDUCT OF NGO PENDING CLOSING

         Section 5.1      OPERATION OF THE BUSINESS OF NGO.  Between the date
of this Agreement and the Closing Date, H&P will, and will cause NGO to, (i)
conduct the business and operations of NGO only in the Ordinary Course of
Business of NGO and in material compliance with all Applicable Laws, (ii) use
their reasonable commercial efforts to preserve, maintain and protect the
Assets in as good repair and condition as on the date of this Agreement,
ordinary wear and tear excepted, (iii) use their reasonable commercial efforts
to preserve intact the current business organization of NGO, to keep available
the services of the current officers, employees and agents of NGO and to
maintain existing relationships and good will with licensors, licensees,
suppliers, contractors, distributors, customers, landlords, creditors,
employees, agents and other Persons having business relationships with NGO,
(iv) keep in full force and effect insurance and bonds comparable in amount and
scope of coverage to that maintained by, or for the benefit of, NGO on the date
of this Agreement, (v) promptly notify Occidental of any written notice of any
default, termination or cancellation under any Applicable Contract, (vi) confer
with Occidental concerning operational matters of a material nature, and (vii)
otherwise report periodically to Occidental concerning the status of the
business, operations and finances of NGO.

         Section 5.2      RESTRICTIONS ON CERTAIN ACTIONS.  From and after the
date of this Agreement and prior to the Closing, except (i) as otherwise
provided in this Agreement, (ii) as required by Applicable Law, (iii) as set
forth on Schedule 5.2, or (iv) with the prior written consent of Occidental,
H&P shall cause NGO not to:

         (a)     amend its charter or by-laws;

         (b)     issue, sell or deliver (whether through the issuance or
granting of options, warrants, commitments, subscriptions, rights to purchase
or otherwise) any Equity Securities of NGO, or amend in any respect any of the
terms of any securities of NGO;

         (c)     (A) split, combine, reclassify or change any shares of the
capital stock of NGO, (B) declare, set aside or pay any dividend or other
distribution (whether in cash, stock or property or any combination thereof) in
respect of such capital stock, (C) grant any registration rights, (D) purchase,
redeem, retire or otherwise acquire any of its securities, or (E) adopt a plan
of complete or partial liquidation or resolutions providing for, or
authorizing, any liquidation, dissolution, merger, consolidation,
restructuring, recapitalization or other reorganization of NGO;

         (d)     (A) except for intercompany indebtedness owed to H&P, create,
incur, guarantee or assume any obligations for borrowed money or purchase money
indebtedness, or otherwise become liable or responsible for the obligations of
any other Person, (B) make any loans, advances or capital contributions to, or
investments in, any





                                       36
<PAGE>   44




other Person (other than customary travel, relocation or expense advances to
employees), (C) pledge or otherwise encumber any shares of the capital stock of
NGO, or (D) create any Encumbrance (other than Permitted Encumbrances) upon any
of the Assets;

         (e)     pay or increase any bonus, salary or other compensation
payable by NGO to any stockholder, director, officer or (except in the Ordinary
Course of Business of NGO) employee of NGO;

         (f)     enter into, adopt, amend or terminate any bonus, profit
sharing, compensation, savings, insurance, severance, termination, stock
appreciation right, restricted stock, performance unit, stock purchase,
pension, retirement, deferred compensation, collective bargaining, employment
or other employee benefit agreement, trust, plan, fund or other arrangement for
the benefit or welfare of, or with, any director, officer or employee of NGO;

         (g)     acquire, sell (other than sales of inventory in the Ordinary
Course of Business of NGO), lease or otherwise dispose of any of the Assets;

         (h)     acquire (by merger, consolidation or acquisition of stock or
assets or otherwise), form, organize, or invest in, any Person;

         (i)     make any capital expenditure if, after giving effect thereto,
the aggregate amount of all capital expenditures made by NGO from the beginning
of its fiscal year commencing on October 1, 1995 to the date of such
expenditure, shall exceed $2,164,000, except as necessary in an emergency
situation, provided that H&P shall, or shall cause NGO to, give to Occidental
notice as soon as reasonably possible of such emergency situation;

         (j)     waive, release, grant, cancel or transfer any claims or rights
with a value to NGO in excess of $25,000;

         (k)     make any change in the accounting methods, principles or
practices of NGO;

         (l)     except in the Ordinary Course of Business of NGO, enter into,
amend, modify, terminate, renew (other than automatic renewals in accordance
with the terms of any Applicable Contract) or change any Applicable Contract;

         (m)     other than intercompany transactions between H&P and NGO in
the Ordinary Course of Business of NGO, enter into any transaction with any
Person that is an Affiliate of NGO;

         (n)     take any action which would, or might, (A) make any of the
representations or warranties of H&P set forth in this Agreement (taking into
account any amendment, referred to in Section 12.9(b), to any of the Schedules)
untrue or inaccurate





                                       37
<PAGE>   45




as of any time from the date of this Agreement to the Closing, or (B) result in
any of the conditions set forth in this Agreement not being satisfied; or

         (o)     authorize or propose, or agree in writing or otherwise to
take, any of the actions described in this Section 5.2.

                                   ARTICLE VI

                             ADDITIONAL AGREEMENTS

         Section 6.1      GENERAL.  Prior to the Closing, each of the Parties
shall refrain, and shall cause each of its Affiliates to refrain, from taking
any action that would (i) prevent or invalidate the consummation of the
transactions contemplated by this Agreement, or (ii) cause this Agreement or
the transactions contemplated hereby to violate any Law.  Each of the Parties
shall endeavor in good faith to cause the conditions (a) to its obligations to
close, and (b) to the obligations of the other Parties to close, to be
fulfilled at or prior to the Closing.

         Section 6.2      REQUIRED CONSENTS.  Each of the Parties shall use its
reasonable commercial efforts to obtain all Consents of, and to effect all
declarations, filings and registrations with, all Persons (including
Governmental Bodies) that are necessary or required for the consummation by
such Party of the transactions contemplated herein.  Each of the Parties shall
cooperate with the other Parties with respect to all such (i) Consents to be
obtained by such Parties, or (ii) declarations, filings or registrations to be
made by such Parties.

         Section 6.3      ACCESS TO INFORMATION.  Between the date of this
Agreement and the Closing, H&P will, and will cause NGO and its Representatives
to, (i) afford Occidental and its Representatives full and free access during
normal business hours to each of NGO's properties (including subsurface
testing), Assets, Contracts, books and records, and other documents and data,
(ii) furnish Occidental and such Representatives with copies of all such
Contracts, books and records, and other documents and data, as Occidental may
reasonably request, and (iii) furnish Occidental and such Representatives with
such additional financial, operating, and other data and information, as
Occidental may reasonably request.

         Section 6.4      NOTIFICATION OF CERTAIN MATTERS.  H&P will promptly
notify Occidental of (i) the discovery of any fact or circumstance, or the
occurrence or nonoccurrence of any event, which would be likely to cause any
representation or warranty made by H&P in this Agreement to be untrue or
inaccurate prior to the Closing, and (ii) any material failure of H&P or NGO to
comply with, or to satisfy, any covenant, condition or agreement to be complied
with or satisfied by it hereunder.  Occidental will promptly notify H&P of (A)
the discovery of any fact or circumstance, or the occurrence or nonoccurrence
of any event, which would be likely to cause any representation or warranty
made by Occidental in this Agreement to be untrue or inaccurate prior to the





                                       38
<PAGE>   46




Closing, and (B) any material failure of Occidental or the Company to comply
with, or to satisfy, any covenant, condition or agreement to be complied with
or satisfied by it hereunder.

         Section 6.5      NO SHOPPING.  From and after the date of this
Agreement and until the earlier of (i) the Closing, or (ii) the termination of
this Agreement in accordance with its terms, H&P shall, and shall cause each of
its Affiliates to, refrain from taking any action, directly or indirectly,
through any officer, director, employee, agent or representative, to solicit or
knowingly encourage, including by way of furnishing information, the initiation
of any inquiries or proposals regarding, or engage in any discussions or enter
into any agreements regarding, any merger, tender offer, sale of shares of
capital stock or assets (other than in the Ordinary Course of Business of NGO),
business combination or similar transaction involving NGO.

         Section 6.6      PERMITS.  H&P shall use, and shall cause NGO to use,
its reasonable commercial efforts (i) to keep all Permits referred to on
Schedule 3.20 in effect until the Closing, and (b) to apply for renewal of each
such Permit that is scheduled to terminate or expire prior to 45 days after the
Closing Date.

         Section 6.7      EMPLOYEES AND EMPLOYEE BENEFIT PLANS.

         (a)     For the purposes of this Section 6.7, "Employees" shall mean
the employees employed by NGO after the Closing Date who are, immediately prior
to the Closing, (i) in the active employment of NGO, or (ii) on short term
disability, sick leave, or other short leave of absence approved by NGO or H&P
and who return to work prior to the earlier of (A) the applicable entitlement
period under the long term disability plan of H&P or NGO or (B) six months
subsequent to the Closing.  A true and complete list of the names, positions,
salaries (or hourly rates, as applicable) and the last bonus of each of the
Employees shall be provided by H&P to Occidental no later than 4 days after the
date of this Agreement and shall be updated by H&P from time to time up to the
Closing.

         (b)     Immediately following the Closing Date, Occidental, or one of
its Affiliates, shall employ, or shall cause NGO to continue to employ, all of
the Employees on an at-will basis.

         (c)     Nothing expressed or implied in this Agreement shall confer
upon any Employee, or any legal representative thereof, any rights or remedies,
including any right to employment, whether directly or as a third party
beneficiary, or continued employment for any specified period, of any nature or
kind whatsoever.

         (d)     Immediately following the Closing Date, Occidental or its
Affiliates shall provide, or shall cause NGO to provide, to each Employee, to
the extent that such Employee is eligible for such benefits immediately prior
to the Closing Date, with the benefit plans and programs listed on Schedule 6.7
to the same extent that similarly situated employees of Occidental or its
Affiliates participate in such plans and programs.





                                       39
<PAGE>   47




Notwithstanding the foregoing, nothing herein shall require Occidental or NGO
to maintain any particular plan, program or arrangement following the Closing
Date.  Under such benefit programs, (i) service with NGO or H&P shall be
counted for purpose of determining any period of eligibility to participate or
vest in benefits, and (ii) Employees  and their eligible dependents (if a
participant in any health, long term disability or life insurance plans, as
applicable, of NGO or H&P immediately prior to the Closing) shall be deemed to
satisfy any pre-existing condition limitations under group medical, dental,
life insurance or disability plans that shall be provided after the Closing
Date, and amounts paid by such Employees towards deductibles and copayment
limitations under the health plans of H&P or NGO shall be counted toward
meeting any similar deductible and copayment limitations under the health plans
that shall be provided after the Closing.

         (e)     Immediately following the Closing Date, H&P and Occidental
shall promptly take the necessary steps, in accordance with Applicable Law, to
provide for a plan to plan transfer of the account balances of the Employees
from the Helmerich & Payne, Inc. 401(k)/Thrift Plan to the Occidental Petroleum
Corporation Savings Plan.

         (f)     H&P shall retain all assets and liabilities with respect to
any Plan or other benefit plan, program or arrangement except (i) with respect
to the Deferred Compensation Agreement, and (ii) as otherwise provided in this
Section 6.7.

         (g)     From and after the Closing, Employees shall be entitled to
retain and take any paid vacation days which accrued from January 1, 1996
through Closing, but which had not been taken as of the Closing under the
vacation policy applicable to such Employees.  On or promptly after the Closing
Date, H&P shall pay the Banked Vacation liability, if any, to any Employee
entitled to such Banked Vacation.  "Banked Vacation" shall mean an amount
payable to any Employee for vacation time that accrued prior to January 1, 1996
and which had not been taken as of the Closing Date.  For purposes of this
Section 6.7(g), vacation time taken during 1996 prior to the Closing shall
reduce vacation time accrued during 1996 prior to the Closing before reducing
any vacation time accrued prior to 1996, unless a different ordering rule is
specified in the vacation policy applicable to Employees.  Banked Vacation to
Employees and any other liability owed to employees who do not become Employees
shall be the responsibility of H&P.

         (h)     H&P agrees that, for Employees with an accrued benefit under
any Pension Plan, H&P shall, effective as of the Closing Date, amend such
Pension Plan so that full vesting in such accrued benefit shall occur as of the
Closing Date.

         (i)     In the event that H&P or NGO terminates any of NGO's employees
at any time prior to the Closing Date, H&P shall be solely responsible for any
liability with respect to such termination, including liability for all
severance benefit payments to any such employee pursuant to its severance plan
and any costs associated with violation of any Applicable Laws.





                                       40
<PAGE>   48




         (j)     H&P shall retain the sole responsibility for, and shall
continue to pay, all hospital, medical, health care continuation coverage
benefits as described in section 4980B of the Code, life insurance, disability,
worker's compensation, and other welfare plan expenses and benefits (including
all benefits under the Plans) for employees of H&P or NGO (including each
Employee) and their covered dependents, including "qualified beneficiaries"
within the meaning of section 607(3) of ERISA, with respect to claims incurred
prior to the Closing.  Expenses and benefits relating to such types of claims
incurred by Employees and their covered dependents on or after the Closing Date
shall be the sole responsibility of Occidental under the terms of its benefit
plans.  In addition, H&P shall retain sole responsibility for the payment of
any claim for hospital, medical benefits, health care continuation coverage
benefits as described in section 4980B of the Code, life insurance, disability,
worker's compensation or other welfare benefits by, or any other item of
compensation or benefits payable under any plan of H&P to, (i) any employee of
H&P after the Closing, (ii) any former employee of H&P or NGO who retired,
died, became disabled or otherwise terminated employment prior to the Closing
Date, or (iii) any Employee who fails or refuses or who otherwise does not
commence active employment with NGO or remain so employed as of the Closing
Date.

         (k)     Representatives of Occidental shall be entitled to meet with
the Employees at mutually agreeable times prior to the Closing to explain and
answer questions about the conditions, policies and benefits of employment by
NGO after the Closing.  H&P shall cooperate with Occidental until Closing in
communicating to such Employees any additional information concerning
employment with NGO after the Closing which such Employees may seek, or which
Occidental may desire to provide, and during normal business hours shall allow
additional meetings by Representatives of Occidental with such Employees of NGO
upon the reasonable requests of Occidental.  In addition, H&P and Occidental
agree to furnish each other with appropriate records for each of the Employees
as may be necessary to assist in proper benefit administration.

         (l)     As of the Closing, NGO shall cease to be a participating
employer in all Pension Plans and Plans sponsored by H&P, and all Employees
shall cease to accrue any future benefits in such Pension Plans and Plans as of
the Closing.

         Section 6.8      NO INTERCOMPANY INDEBTEDNESS OR OBLIGATIONS.  H&P
shall take steps to ensure that, as of the Closing, (i) NGO shall have no
intercompany indebtedness or obligations of any kind owed to H&P or to any
Affiliate of H&P, and (ii) NGO shall have no funded debt obligations for
borrowed money owed to any Person.

         Section 6.9      BOOKS AND RECORDS.

         (a)     DELIVERY.  From and after the Closing and upon the request of
Occidental or the Surviving Corporation, H&P shall deliver to Occidental or the
Surviving Corporation, as the case may be, in Tulsa, Oklahoma, all of NGO's
books and records, including bank account records, accounting records, computer
records and all Applicable Contracts, in the possession of H&P or any of its
Affiliates.





                                       41
<PAGE>   49




         (b)     INSPECTION.  Each Party agrees that, for a period of five
years following the Closing Date, such Party shall take all necessary action to
ensure that (i) all corporate books and records of NGO or pertaining to the
Assets with respect to periods ending on or before the Closing Date and in the
possession or control of such Party or any of its Affiliates shall be open for
inspection by Representatives of the other Party at any time during regular
business hours, and (ii) such other Party may during such period at its expense
make such excerpts therefrom as it may reasonably request.

         (c)     DESTRUCTION AND COOPERATION.  For a period of five years
following the Closing Date (or for such longer period as may be required by
Law), no Party or any of its Affiliates shall destroy or give up possession of
any original or any copy of any of the books and records relating to any matter
for which any other Party shall have any continuing responsibility under this
Agreement without first offering to such Party the opportunity, at its expense,
to obtain such original or a copy thereof.  During such period, each Party
shall use its reasonable commercial efforts to cooperate with each of the other
Parties and make available such records and books to the employees and
Representatives of such Party to the extent that such Party may reasonably
require for its corporate and other business purposes (including attendance at
depositions or legal proceedings, or audits requested by such Party to be
performed by such Party's independent accountants for any period through the
Closing Date).

         Section 6.10     LITIGATION SUPPORT.  In the event and for so long as
any Party actively is contesting or defending against any action, suit,
proceeding, hearing, investigation, charge, complaint, claim or demand in
connection with (i) any transaction contemplated by this Agreement, or (ii) any
fact, situation, circumstance, status, condition, activity, practice,
occurrence, event, incident, action, failure to act, or transaction on or prior
to the Closing Date and involving NGO, each of the other Parties will cooperate
with such Party and its counsel in such contest or defense, make available the
personnel of such other Party, and provide such testimony and access to its
books and records as shall be necessary in connection with such contest or
defense, all at the sole cost and expense of the contesting or defending Party.

         Section 6.11     SECURITIES LAWS AND TRANSFERS; STOCK CERTIFICATES.

         (a)     H&P agrees that it will not transfer or dispose of any of the
shares of the Occidental Common Stock issuable pursuant to the provisions of
this Agreement other than (i) pursuant to an effective registration statement
under the Securities Act and any applicable state securities law, or (ii)
pursuant to an exemption from such registration under the Securities Act and
any such state securities law; provided, however, that such shares shall not be
sold pursuant to the provisions of this clause (ii) in the event that any such
registration statement shall be effective and unless and until (A) H&P shall
have notified Occidental of the proposed disposition and shall have furnished
Occidental with a statement of circumstances surrounding such disposition, and
(B), if requested by Occidental, at the expense of H&P or its transferee, H&P
shall have furnished to Occidental an opinion of





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<PAGE>   50




counsel, reasonably satisfactory to Occidental, to the effect that such
transfer may be made without registration under the Securities Act or any
applicable state securities law.

         (b)     All certificates evidencing the shares of the Occidental
Common Stock issuable pursuant to the provisions of this Agreement shall bear
the following legend:

                 The shares of stock evidenced by this certificate (the
         "Shares") have been acquired for investment and have not been
         registered under the Securities Act of 1933 or any state securities
         law.  The Shares may not be sold, transferred or otherwise disposed of
         except pursuant to an effective registration statement under the
         Securities Act of 1933 or an applicable exemption from registration
         thereunder.

Upon request by H&P, Occidental shall remove promptly the foregoing restrictive
legend when the foregoing restrictions are no longer required by applicable
securities laws.

         (c)     Occidental shall make a notation in its stock books regarding
the restrictions on transfer of the shares of the Occidental Common Stock
issuable pursuant to the provisions of this Agreement, and such shares will be
transferred on the books of Occidental only if transferred or sold in
compliance with the provisions of Section 6.11(a).  Upon request by H&P,
Occidental shall remove promptly such notation when the foregoing restrictions
on transfer are no longer required by applicable securities laws.

         Section 6.12     NO SHORT SALES.  During the period from the date of
this Agreement through the Closing Date, neither H&P nor any of its Affiliates
or any agent acting on behalf of any of them will (i) sell, offer to sell or
commence any sale, solicitation, marketing or other efforts to facilitate the
disposition of any shares of the Occidental Common Stock, or (ii) sell short or
enter into any put equivalent position with respect to any shares of the
Occidental Common Stock.

         Section 6.13     TITLE MATTERS.

         (a)     Occidental has obtained, at Occidental's sole expense, a
Commitment for Title Insurance covering the Baytown Land and all improvements
located thereon (the "Title Commitment") from the Title Company, pursuant to
which the Title Company has agreed to issue to NGO at Closing an Owner Policy
of Title Insurance (the "Title Policy"), which Title Commitment was issued on
August 20, 1996 and has an effective date of August 12, 1996.

         (b)     H&P shall cause the satisfaction or elimination of item 4
listed on Schedule C to the Title Commitment with the result that the Title
Company shall be willing to issue the Title Policy to NGO at the Closing
without exception or condition relating to such item.

         (c)     Prior to the Closing, H&P shall (i) assign its U. S. trademark
application No. 74/733,194 (for CAPTAN), and all of the rights, title and
interest of H&P with





                                       43
<PAGE>   51




respect thereto, to NGO on a form reasonably acceptable to Occidental, (ii)
deliver an original, executed copy of such assignment to Occidental, (iii) file
such assignment of record with the U. S. Patent and Trademark Office, and (iv)
provide written evidence of such filing to Occidental.  H&P represents and
warrants to Occidental that neither such application nor the rights of H&P to
such trademark are subject to any Encumbrances.

         Section 6.14     INSURANCE.

         (a)     H&P shall, and, prior to the Closing, shall cause NGO to, give
timely notice to NGO's insurers of any claims which shall become known to H&P
or NGO between the date of this Agreement and the Closing Date and which, to
the Knowledge of H&P, could potentially exceed NGO's retention or deductible
levels.

         (b)     H&P shall use its reasonable commercial efforts to provide
copies of any occurrence-based insurance policies which Occidental or NGO may
in the future request in connection with claims brought after the Closing Date
and which relate to occurrences prior to the Closing Date.  Subject to Section
6.14(c), NGO shall retain the right to make claims relating to pre-Closing Date
occurrences against any of H&P's occurrence-based policies which insured NGO.

         (c)     Neither Occidental nor NGO will submit, after the Closing
Date, any claims against the National Union Policy; provided, however, that NGO
may pursue claims noticed or tendered to the National Union Policy on or before
the Closing Date.

         (d)     NGO shall have the right to negotiate and conclude any
pre-Closing Date claims noticed or tendered to NGO's insurers on or before the
Closing Date under any policies insuring NGO.

         (e)     In the event that H&P or any of its Affiliates shall receive
or otherwise collect any amounts relating to claims involving NGO occurrences,
H&P shall, or shall cause such Affiliate to, remit such amounts to Occidental
within fifteen days after receipt thereof by H&P or such Affiliate, as the case
may be.

         (f)     H&P shall not modify or cancel coverage under (i) any of the
policies of H&P which provide coverage to NGO for pre-Closing Date occurrences,
or (ii) any other policies which cover any claims of NGO still outstanding on
the Closing Date.

         (g)     H&P and Occidental will cooperate with each other to cause to
be terminated, released and discharged, on the Closing Date or as soon as
practicable thereafter, each surety bond which is listed on Schedule 3.26.5.
With respect to each such surety bond which shall not have been so terminated,
released and discharged, Occidental shall, from and after the Closing Date,
cause NGO to perform and comply, in all material respects, with all of the
terms and conditions of such surety bond.





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<PAGE>   52




         (h)     H&P shall not at any time provide insurance coverage for NGO
or Occidental for claims which relate to post-Closing Date occurrences.

         6.15    LISTING OF SHARES OF THE OCCIDENTAL COMMON STOCK.   Prior to
the Closing Date, Occidental shall make application to supplement its listing
agreements with the New York Stock Exchange, Inc. and the Pacific Stock
Exchange Incorporated so as to cause the shares of the Occidental Common Stock
issuable pursuant to the provisions of this Agreement to be listed thereon upon
issuance or as soon thereafter as practicable.

                                  ARTICLE VII

                                  TAX MATTERS

                 Section 7.1      REPRESENTATIONS, WARRANTIES AND COVENANTS OF
H&P.  H&P represents and warrants to Occidental, and covenants, as follows:

         (a)     TAX RETURNS.

                 (1)      H&P has prepared, shall prepare or shall cause to be
prepared, and has timely filed, shall timely file or shall cause to be timely
filed, all Tax Returns required by applicable law to be filed by H&P or NGO for
all taxable periods ending on or prior to the Closing Date, and H&P will use
its reasonable efforts to ensure that all such Tax Returns to be so filed after
the date of this Agreement will be true, complete and correct in all material
respects.

                 (2)      Except in connection with Section 7.1(a)(3), H&P
shall not make any tax elections in its or NGO's Tax Returns for any taxable
period ending on, prior to, or commencing prior to and ending after, the
Closing Date, which could be binding upon NGO or increase the amount of Taxes
for which NGO may be liable without the express, written approval of
Occidental.

                 (3)      NGO is a member of an affiliated group of
corporations filing U.S. Federal income tax returns of which H&P is the common
parent (the "Helmerich & Payne Group").  The Helmerich & Payne Group files its
Tax Returns on a fiscal year ending September 30.  The items of income, gain,
deduction, loss and credit of NGO, including foreign tax credits, state tax
deduction and other similar tax attributes of NGO affecting H&P's consolidated
or combined taxable income from October 1, 1995 through the Closing Date shall
be included in the consolidated or combined taxable income of the Helmerich &
Payne Group in accordance with Treasury Regulations Section 1.1502-76(b), for
U.S. Federal income tax and that of the states of Oklahoma, California and
Kansas.  H&P shall not be required to file any other Tax Returns except those
required by Sections 7.1(a)(1) and 7.1(a)(3).

         (b)     PAYMENT OF TAXES.  H&P or NGO has paid, will pay (or will have
paid on their behalf) within the time and in the manner prescribed by law, or
where payment is





                                       45
<PAGE>   53




not yet due, has established (or has had established on their behalf), or will
establish or cause to be established on or before the Closing Date, an accrual,
as set forth in Schedule 7.4, for the payment of, such taxes (including any
interest, additions to tax, or penalties applicable thereto) due from H&P or
NGO after the date of this Agreement as are indemnified by H&P pursuant to the
provisions of Section 7.4.

         (c)     AUDITS, PROCEEDINGS AND LITIGATION.

                 (1)      There is not any current, pending or threatened Audit
of, assessment against, or litigation or other Proceeding against, H&P or NGO
with respect to any Taxes due from H&P or NGO for which NGO may be liable.

                 (2)      Neither H&P nor NGO is subject to, bound by, or a
party to, any agreement relating to Taxes, including any agreement with any Tax
Authority, that can affect a taxable period for which NGO may be liable, except
for (i) a Code Section 481(a) adjustment relating to capitalization of sales
tax, and (ii) the Industrial District Agreement, dated December 19, 1995,
between the City of Baytown, Texas, and NGO relating to real or personal
property tax.  H&P has delivered to Occidental true and complete copies of (A)
the Consent Agreement, dated on or about August 15, 1995, between the Internal
Revenue Service and H&P with respect to such adjustment, and (B) such
Industrial District Agreement.

                 (3)      There are no extensions of the statutory period of
limitations relating to the assessment or payment of Taxes due from H&P or NGO
for any taxable period for which NGO may be liable.  No issue has been raised
in any Audit of NGO or H&P as a result of which NGO may be liable for any
Taxes.

         (d)     TAX LIENS.  There are no liens for Taxes upon any of the
assets of H&P or NGO, except liens for Taxes not yet due and payable, for which
NGO may be liable.

         (e)     TAX BASIS.  The cumulative regular tax basis of all the assets
of NGO as of the Closing Date, net of any and all adjustments required by the
provisions of the Code, shall be provided to Occidental by H&P within 45 days
of the Closing Date.

         Section 7.2  REPRESENTATIONS, WARRANTIES AND COVENANTS OF OCCIDENTAL.
Occidental represents and warrants to H&P, and covenants, as follows:

         (a)     Immediately following the Merger, NGO will hold at least 90
percent of the fair market value of the Company's net assets and at least 70
percent of the fair market value of the Company's gross assets held immediately
prior to the Merger.

         (b)     Prior to the Merger, Occidental will be in control of the
Company within the meaning of Section 368(c) of the Code.





                                       46
<PAGE>   54




         (c)     Occidental has no plan or intention to reacquire any of its
stock issued in the Merger.

         (d)     Occidental has no plan or intention to liquidate NGO; to merge
NGO with or into another corporation; to sell or otherwise dispose of the stock
of NGO except for transfers of stock to corporations controlled by Occidental;
or to cause NGO to sell or otherwise dispose of any of its assets or of any of
the assets acquired from the Company, except for dispositions made in the
ordinary course of business or transfers of assets to a corporation controlled
by NGO, and except for transfers described in Section 368(a)(2)(C) of the Code
and Treasury Regulation Section 1.368-2(j)(4).

         (e)     The Company will have no liabilities assumed by NGO, and will
not transfer to NGO any assets subject to liabilities, in the Merger.

         (f)     For the shorter of (i) the period required to comply with
Treasury Regulation Section 1.368-1(d) and applicable case law, or (ii) the
period of two years immediately following the Merger, NGO will continue its
historic business or use a significant portion of its historic business assets
in a business within the meaning of such Treasury Regulation and applicable
case law.

         (g)     Occidental will pay all of the expenses incurred by Occidental
or the Company in connection with the Merger.

         (h)     There is no intercorporate indebtedness existing between
Occidental and NGO or between the Company and NGO that was issued, acquired, or
will be settled at a discount.

         (i)     Occidental does not own, directly or indirectly, nor has it
owned during the past five years, directly or indirectly, any stock of NGO.

         (j)     Occidental has no plan or intention as part of the Merger to
cause NGO to issue after the Closing additional shares of its stock that would
result in Occidental losing control of NGO within the meaning of Section 368(c)
of the Code or any warrants, options, convertible securities, or any other type
of right pursuant to which any person could acquire stock in NGO that, if
exercised or converted, would affect Occidental's acquisition or retention of
control of NGO, as defined in Section 368(c) of the Code.

         (k)     Occidental will acquire the NGO Common Stock, which
constitutes "control" of NGO within the meaning of Section 368(c) of the Code,
from H&P solely in exchange for Occidental voting stock.  No liabilities of NGO
or H&P will be assumed by Occidental.





                                       47
<PAGE>   55




         (l)     Occidental shall provide H&P with copies of any Tax Returns
covering any taxable period of NGO which commences prior to and ends after the
Closing Date at least 30 days prior to filing such returns.

         (m)     Occidental shall not file any amendments in its or NGO's Tax
Returns for any taxable period ending on or prior to the Closing Date, which
could be binding upon H&P or increase the amount of Taxes for which H&P may be
liable without the express, written approval of H&P.  Occidental shall not make
any tax elections in its or NGO's Tax Returns for any taxable period commencing
prior to and ending after the Closing Date, which could be binding upon H&P or
increase the amount of Taxes for which H&P may be liable without the express,
written approval of H&P.

         Section 7.3  REFUNDS, CARRYOVER, ETC.

         (a)     All refunds of Taxes arising from (i) Tax Returns required by
Section 7.1(a)(3) for the period October 1, 1995 through the Closing Date, (ii)
any other U.S. Federal or Oklahoma, California or Kansas income tax return
filed by H&P on a consolidated or combined basis, and (iii) any Canadian
federal or provincial income tax for (A) the period October 1, 1995 through the
Closing Date, and (B) taxable periods ending on or prior to the Closing Date,
shall be the sole property of H&P.

         (b)     All refunds of Taxes for any taxable period (other than those
described in Section 7.3(a)) shall be the sole property of Occidental.

         (c)     Any benefit of any unutilized net operating loss, net capital
loss, foreign tax credit or other carryover to any taxable period commencing
prior to and ending after, or commencing after, the Closing Date, shall be the
sole property of Occidental, to the extent not utilized by H&P or NGO in Tax
Returns to be filed by H&P required by Sections 7.1(a)(1) and 7.1(a)(3).

         (d)     If (i) H&P receives any refund, credit or other benefit
described in this Section 7.3 which belongs to Occidental, or (ii) Occidental
receives any refund, credit or other benefit described in this Section 7.3
which belongs to H&P, H&P or Occidental, as the case may be, shall pay to H&P
or Occidental the entire amount of such refund, credit or other benefit within
15 days of its receipt of the same.

         Section 7.4  INDEMNIFICATION FOR TAXES.

         (a)     INDEMNIFICATION BY H&P.  Schedule 7.4 is a complete and
accurate list, as of August 30, 1996, of all accruals and reserves maintained
in the balance sheets of NGO and H&P for accrued Taxes for the taxable year
1996.  H&P agrees to indemnify and hold harmless Occidental and its successors
and assigns from any and all liabilities with respect to (i) all taxes
(including any interest, additions to tax, or penalties applicable thereto) of
H&P or NGO arising from (A) U. S. Federal, Oklahoma, California or Kansas
income tax returns for the period from October 1, 1995 through the Closing





                                       48
<PAGE>   56




Date, to the extent in excess of any accruals or reserves for Taxes reflected
in the balance sheets of NGO and H&P and as set forth in Schedule 7.4, and (B)
any other U.S. Federal, Oklahoma, California or Kansas income tax return, and
any amendment thereto, in each case filed by H&P on a consolidated or combined
basis, and (ii) 50% of all taxes (including any interest, additions to tax, or
penalties applicable thereto) of H&P or NGO arising from any Texas franchise
tax returns and any amendments thereto filed by NGO for taxable periods ending
prior to the Closing Date; provided, however, that the obligations of H&P
pursuant to the provisions of clause (ii) of this Section 7.4(a), with respect
to any such taxes arising from any such Texas franchise tax return or amendment
for any taxable period which shall include October, November and December 1995,
shall be 50% of the difference between (1) the amount of such taxes (including
any interest, additions to tax, or penalties applicable thereto), and (2)
$55,645.

         (b)     PAYMENTS.  Payment of any amount due to Occidental under this
Section 7.4 shall be made within 15 days following the written request by the
Party which made a payment to a Tax Authority, which request shall include
proof of payment by such Party.

         Section 7.5  CONTEST PROVISION.  H&P shall notify Occidental, and
Occidental shall notify H&P, within 15 days in writing upon receipt by H&P or
any Affiliate thereof, or by Occidental or any Affiliate thereof, as the case
may be, of each written or oral communication addressed to H&P, Occidental or
NGO for any taxable period which could give rise to a claim for indemnification
under Section 7.4.  In the case of any written communication received, H&P or
Occidental shall include with the notice to Occidental or H&P, as the case may
be, a true, correct and complete copy of the communication received.  H&P shall
have the sole right to represent the interests of NGO in any Audit, protest of
other proceedings relating to a payment subject to the indemnification set
forth in Section 7.4(a), to employ counsel of its choice and otherwise control
the conduct of such Audit, protest or other proceedings, provided, however,
that (i) Occidental shall have the right to participate in such Audit, protest
or other proceedings, and (ii) H&P shall not settle any issue with respect to
such Audit, protest or other proceedings which may increase the amount of Taxes
for which NGO may be liable without the express, written consent of Occidental.

         Section 7.6  COOPERATION.  H&P and Occidental will provide each other
with such cooperation and information as H&P or Occidental may request of the
other and as is reasonably necessary in filing any Tax Return, or claim for
refund, determining a liability for Taxes or a right to a refund of Taxes, or
in conducting any Audit or other Proceeding in respect of Taxes.  Such
cooperation shall include, but not be limited to, making employees available on
a mutually convenient basis to provide explanation of any documents or
information provided hereunder or otherwise as required in the conduct of any
Audit or other Proceeding.  H&P shall retain all Tax Returns, schedules and
work papers and all material records or other documents relating to matters of
NGO relating to Taxes for the period of seven years from the Closing Date, and,
at the expiration of such period, H&P or Occidental shall have the right to
dispose of any such Tax Returns or other documents after providing 90 days'
notice to H&P or Occidental, as the case may





                                       49
<PAGE>   57




be.  Any information obtained under this Section 7.6 shall be kept
confidential, except as may be otherwise necessary in connection with the
filing of Tax Returns or claims for refund or in conducting an Audit or other
Proceeding.

         Section 7.7  TRANSFER TAXES.  Notwithstanding the provisions of
Section 7.1 and 7.4, Occidental and H&P shall each pay their respective
transfer, documentary, excise, stamp and other similar taxes, fees or
governmental charges that may be imposed by law upon each such Party in respect
of the transactions contemplated by this Agreement.

         Section 7.8  SURVIVAL.  Notwithstanding any other provision of this
Agreement, (i) all of the representations, warranties and covenants set forth
in Sections 7.1 and 7.2 pertaining to any Tax shall survive the Closing and
until the applicable Tax law statute of limitations, including any extensions
thereof, with respect to such Tax shall have expired, and (ii) the
indemnification obligations of H&P set forth in Section 7.4 pertaining to any
Tax shall survive the Closing and until six months after the applicable Tax law
statute of limitations, including extensions, with respect to such Tax shall
have expired.

         Section 7.9  CONDUCT OF H&P BEFORE CLOSING.  From and after the date
of this Agreement and prior to the Closing, except with the prior written
consent of Occidental, H&P shall cause NGO not to:

         (i)     enter into any settlement of any issue with respect to any
                 Audit;

         (ii)    execute any consent to extend any statute of limitations with
                 respect to Taxes; or

         (iii)   execute any consent to extend any due date for the filing of
                 any Tax Return.

                                  ARTICLE VIII

            CONDITIONS TO OBLIGATIONS OF OCCIDENTAL AND THE COMPANY

           The obligations of Occidental and the Company to consummate the
transactions contemplated by this Agreement shall be subject to the
satisfaction, at or prior to the Closing, of each of the following conditions
(any of which may be waived by Occidental and the Company, in whole or in
part):

         Section 8.1      ACCURACY OF REPRESENTATIONS.  The representations and
warranties made by H&P in this Agreement shall be true and correct in all
material respects as of the Closing (taking into account any amendment,
referred to in Section 12.9(b), to any of the Schedules), with the same effect
as though such representations and warranties had been made as of the Closing
(except (i) to the extent that such representations and warranties expressly
relate to an earlier date, and (ii) as provided in this Agreement).





                                       50
<PAGE>   58




         Section 8.2      PERFORMANCE BY H&P AND NGO.  H&P and NGO shall have
performed, and complied with, all of the covenants and obligations required by
this Agreement to be performed and complied with by H&P or NGO, as the case may
be, on or prior to the Closing.

         Section 8.3       NO PROCEEDINGS OR ORDERS.  No Proceeding or Order
shall, on the Closing Date, be pending, threatened or in effect that (i)
challenges, or that may have the effect of preventing, restraining,
prohibiting, delaying, making illegal, obtaining damages or other relief in
connection with, or otherwise interfering with, this Agreement or any of the
transactions contemplated hereby, or (ii) would impose any material limitation
on the ability of Occidental to exercise full rights of ownership of the shares
of the Surviving Corporation or of NGO to exercise full rights of ownership of
the Assets, and no director or officer of NGO shall have notified Occidental in
the letters referred to in clause (v) of Section 2.4(b) of any claim for
indemnification from NGO.

         Section 8.4      CONSENTS.  All Consents of, and declarations, filings
or registrations with, all Persons (including Governmental Bodies) required to
be obtained or made by or on behalf of H&P or NGO in connection with the
execution, delivery or performance by the Parties of this Agreement, or
otherwise reasonably required for the consummation of the transactions
contemplated hereby, shall have been obtained or made, and all thereof shall be
in full force and effect at the Closing.

         Section 8.5      NOVATION AGREEMENT.  National Union Fire Insurance
Company of Pittsburgh, PA. shall have executed and delivered a copy of the
Novation Agreement to Occidental.

         Section 8.6      DELIVERY OF DOCUMENTS.  H&P shall have delivered to
Occidental each of the certificates, instruments, documents and other items to
be delivered by H&P to Occidental pursuant to the provisions of Section 2.4(b).


                                   ARTICLE IX

                    CONDITIONS TO OBLIGATIONS OF H&P AND NGO

           The obligations of H&P and NGO to consummate the transactions
contemplated by this Agreement shall be subject to the satisfaction, at or
prior to the Closing, of each of the following conditions (any of which may be
waived by H&P and NGO, in whole or in part):





                                       51
<PAGE>   59




         Section 9.1      ACCURACY OF REPRESENTATIONS.  The representations and
warranties made by Occidental in this Agreement shall be true and correct in
all material respects as of the Closing with the same effect as though such
representations and warranties had been made as of the Closing (except (i) to
the extent that such representations and warranties expressly relate to an
earlier date, and (ii) as provided in this Agreement).

         Section 9.2      PERFORMANCE BY OCCIDENTAL AND THE COMPANY.
Occidental and the Company shall have performed, and complied with, all of the
covenants and obligations required by this Agreement to be performed and
complied with by Occidental or the Company, as the case may be, on or prior to
the Closing.

         Section 9.3       NO PROCEEDINGS OR ORDERS.  No Proceeding or Order
shall, on the Closing Date, be pending, threatened or in effect that (i)
challenges, or that may have the effect of preventing, restraining,
prohibiting, delaying, making illegal, obtaining damages or other relief in
connection with, or otherwise interfering with, this Agreement or any of the
transactions contemplated hereby, or (ii) would impose any material limitation
on the ability of H&P to exercise full rights of ownership of the shares of the
Occidental Common Stock to be acquired by H&P pursuant to the provisions of
this Agreement.

         Section 9.4      CONSENTS.  All Consents of, and declarations, filings
or registrations with, all Persons (including Governmental Bodies) required to
be obtained or made by or on behalf of the Parties in connection with the
execution, delivery or performance by the Parties of this Agreement, or
otherwise reasonably required for the consummation of the transactions
contemplated hereby, shall have been obtained or made, and all thereof shall be
in full force and effect at the Closing.

         Section 9.5      NOVATION AGREEMENT.  National Union Fire Insurance
Company of Pittsburgh, PA. shall have executed and delivered a copy of the
Novation Agreement to H&P.

         Section 9.6      DELIVERY OF DOCUMENTS.  Occidental shall have
delivered to H&P each of the certificates, instruments, documents and other
items to be delivered by Occidental to H&P pursuant to the provisions of
Section 2.4(c).

         Section 9.7      LEGAL MATTERS.  All actions, proceedings, instruments
and other documents required to consummate the transactions contemplated by
this Agreement, and all other related legal matters, shall be reasonably
satisfactory to counsel to H&P and NGO.





                                       52
<PAGE>   60





                                   ARTICLE X

                                  TERMINATION

         Section 10.1     TERMINATION EVENTS.  This Agreement may be terminated
and the transactions contemplated hereby abandoned, (except as set forth in
clause (iv) of this Section 10.1) at any time prior to the Closing, in the
following manner:

         (i)     By mutual written consent of Occidental and H&P; or

         (ii)    By Occidental in the event that (A) H&P or NGO shall have
breached any representation, warranty, covenant or agreement contained in this
Agreement in any material respect, and such breach shall not have been waived
by Occidental, (B) H&P shall amend any of the Schedules pursuant to the
provisions of Section 12.9(b) to disclose the occurrence of any event between
the date of this Agreement and the Closing Date and, absent such amendment, H&P
or NGO would have so breached any such representation, warranty, covenant or
agreement, and such breach shall not have been waived by Occidental, (C) H&P
shall amend any of the Schedules pursuant to the provisions of Section 12.9(b)
to disclose the occurrence of any event on or before the date of this Agreement
(without regard to the materiality of such event), (D) H&P shall amend Schedule
3.15 pursuant to the provisions of Section 12.9(b) to disclose the occurrence
of any event (whether such event shall have occurred before, on or after the
date of this Agreement and without regard to the materiality of such event), or
(E) the Closing shall not have occurred on or before the Termination Date by
reason of the failure of any condition precedent set forth in Article VIII; or

         (iii)   By H&P in the event that (A) Occidental or the Company shall
have breached any representation, warranty, covenant or agreement contained in
this Agreement in any material respect, and such breach shall not have been
waived by H&P, or (B) the Closing shall not have occurred on or before the
Termination Date by reason of the failure of any condition precedent set forth
in Article IX; or

         (iv)    By H&P, not later than one day prior to the Closing Date, in
the event that the Closing Stock Price shall be less than $21.50; or

         (v)     By either Occidental or H&P if the Closing shall not have
occurred on or before the Termination Date, unless such failure to close shall
be due to a breach of this Agreement by the Party seeking to terminate this
Agreement pursuant to this clause (v).

         Section 10.2     EFFECT OF TERMINATION.  In the event of the
termination of this Agreement by H&P or Occidental pursuant to the provisions
of Section 10.1, notice thereof shall forthwith be given by H&P or Occidental,
as the case may be, to the other Parties specifying the provision hereof
pursuant to which such termination shall be made, and this Agreement shall
become void and have no effect, and there shall be no liability hereunder on
the part of any Party with respect to this Agreement, except that the
agreements set forth in this Section 10.2 and in Sections 12.1, 12.2, 12.3,
12.4, 12.5, 12.6,





                                       53
<PAGE>   61




12.8, 12.9(a), 12.10, 12.11, 12.12, 12.13, 12.14, 12.15 and 12.16 shall survive
such termination; provided, however, that any termination pursuant to the
provisions of clauses (ii)(A) or (iii)(A) of Section 10.1 shall not relieve any
Party from any liability to the other Party for damages actually incurred as a
result of any breach of this Agreement, and no such termination shall be deemed
to be a waiver of any applicable remedy (including specific performance or
injunctive or other equitable relief) for any such breach.

                                   ARTICLE XI

                   SURVIVAL OF REPRESENTATIONS AND WARRANTIES

         Section 11.1     SURVIVAL.

         (a)     Except as otherwise stated in Sections 11.l(b), (c), (d) and
(e), all representations and warranties set forth in this Agreement or in any
writing delivered concurrently herewith or subsequent hereto expressly pursuant
to the provisions of this Agreement will not survive the Closing.

         (b)     The representations and warranties of H&P set forth in the
following Sections shall survive up to, and including, the third anniversary of
the Closing, after which such representations and warranties shall terminate
and be of no further force or effect:    3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7,
3.8, 3.18(c), 3.27(k), 3.32, 3.33 and 3.35.

         (c)     The representation and warranty of H&P set forth in Section
3.12 shall, with respect to all personal property (whether tangible or
intangible) covered by such representation and warranty, survive up to, and
including, the date which shall occur 180 days after the Closing Date, after
which such representation and warranty shall terminate and be of no further
force or effect.

         (d)     The representations and warranties of Occidental set forth in
the following Sections shall survive up to, and including, the third
anniversary of the Closing, after which such representations and warranties
shall terminate and be of no further force or effect:      4.1, 4.2, 4.3, 4.4,
4.5, 4.7, 4.8, 4.9 and 4.10.

         (e)     The representations, warranties and covenants set forth in
Sections 7.1 and 7.2, and the indemnification obligations of H&P set forth in
Section 7.4, shall terminate as provided in Section 7.8.

         (f)     Nothing set forth in this Article XI shall at any time relieve
any Party from the performance of its covenants, agreements, undertakings and
indemnities set forth in this Agreement.  Such covenants, agreements,
undertakings and indemnities shall survive the Closing.





                                       54
<PAGE>   62





                                  ARTICLE XII

                                 MISCELLANEOUS

         Section 12.1     CONFIDENTIALITY.  Each Party (other than, in the case
of clause (i) of this Section 12.1, NGO) shall, and shall cause its Affiliates,
employees, agents, accountants, legal counsel and other representatives to,
hold in strict confidence, and not utilize for any commercial or other purpose
whatsoever, information of any kind concerning (i) NGO or its business, or (ii)
the transactions contemplated by this Agreement, in each case obtained from any
other Party or any of its Affiliates, employees, agents, accountants, legal
counsel or other representatives (hereinafter such information is referred to
as the "Information"); provided, however,  that the foregoing obligation of
confidence shall not apply to (A) any Information that is or shall become
generally available to the public other than as a result of a disclosure by
such Party, any of its Affiliates or the respective employees, agents,
accountants, legal counsel or other representatives of such Party or any such
Affiliate, (B) any Information that is or shall become available to such Party
or its employees, agents, accountants, legal counsel or other representatives
prior to the Closing on a nonconfidential basis prior to its disclosure by such
Party or its employees, agents, accountants, legal counsel or other
representatives, and (C) any Information that shall be required to be disclosed
by such Party, any of its Affiliates or the respective employees, agents,
accountants, legal counsel or other representatives of such Party or any such
Affiliate as a result of any offering of securities of such Party or of any
such Affiliate or otherwise, in each case under any Law or any rule or
regulation of any stock exchange.  The obligations of each Party under this
Section 12.1 shall terminate on (1) the Closing Date, or (2) on July 31, 2001,
if the Closing shall not occur.  In the event that the Closing shall not occur,
each Party will return to any other appropriate Party, or destroy, as much of
the Information which shall be in the possession of such Party as such other
Party shall request.

         Section 12.2     PRESS RELEASES AND PUBLIC ANNOUNCEMENTS.  Prior to
the Closing, the Parties shall not, and shall not permit any of their
respective Affiliates to, issue any press release or other public announcement
relating to the subject matter of this Agreement (other than presentations to
security analysts and financial institutions) except (i) with the prior
approval of the other Parties, (ii) when, on the advice of legal counsel, such
release or announcement is required by the federal securities laws or the rules
and regulations of any of the national stock exchanges (in which case the
disclosing Party shall consult with the other Parties prior to making the
disclosure), and (iii) either H&P or Occidental may, upon execution of this
Agreement, issue a press release and file any report required by such laws,
rules or regulations disclosing, in each case, such execution, the anticipated
Closing Date and the terms of the transactions contemplated by this Agreement
set forth in Sections 2.1 and 2.3.  Each Party will consult with the other
Parties concerning the means by which the employees, customers and suppliers of
NGO and other Persons having dealings with NGO will be informed of the
transactions contemplated by this Agreement.

         Section 12.3     NO THIRD-PARTY BENEFICIARIES.  NOTHING CONTAINED IN
THIS AGREEMENT, EXPRESS OR IMPLIED, IS INTENDED TO CONFER UPON ANY





                                       55
<PAGE>   63




PERSON, OTHER THAN THE PARTIES AND THEIR RESPECTIVE SUCCESSORS AND PERMITTED
ASSIGNS, ANY RIGHTS, REMEDIES OR OBLIGATIONS UNDER, OR BY REASON OF, THIS
AGREEMENT.

         Section 12.4     ENTIRE AGREEMENT.  This Agreement (including the
documents attached hereto) constitutes the entire agreement among the Parties
and supersedes all prior understandings and agreements, including, but not
limited to, the Confidentiality Agreement and the Letter of Intent, with
respect to the subject matter hereof or thereof.

         Section 12.5     EXPENSES.  Except as otherwise provided herein or in
any Related Document, each of the Parties will bear all of its own costs and
expenses (including, without limitation, the fees and expenses of legal
counsel, accountants and other advisors, which, in the case of H&P, shall
include the fees and expenses of Smith Barney Inc.) incurred in connection with
this Agreement or any Related Document and the transactions contemplated hereby
or thereby and whether or not the Closing shall have occurred.  None of H&P's
costs or expenses shall be borne by NGO.  Such costs and expenses which shall
be borne by H&P, and not by NGO, shall include all costs or expenses incurred
or paid after March 31, 1996 and prior to the Closing by H&P or NGO, in excess
of an aggregate of $50,000, in connection with any corrective, investigative or
remedial measure relating to any Hazardous Materials or the Environment.
Notwithstanding the foregoing, NGO shall bear all of such costs and expenses of
installation of concrete containment and pressure vessel replacement.

         Section 12.6     BROKERAGE INDEMNITIES.  Regardless of whether the
Closing shall occur, (i) H&P shall indemnify and hold harmless Occidental and
its Affiliates from and against any and all liability for any brokers or
finders fees arising with respect to any brokers or finders (including, without
limitation, Smith Barney Inc.) retained or engaged by H&P or any of its
Affiliates in respect of the transactions contemplated by this Agreement, and
(ii) Occidental shall indemnify and hold harmless H&P and its Affiliates from
and against any and all liability for any brokers or finders fees arising with
respect to any brokers or finders retained or engaged by Occidental or any of
its Affiliates in respect of the transactions contemplated by this Agreement.

         Section 12.7     INDEMNIFICATION ARRANGEMENTS FOR DIRECTORS AND
OFFICERS, ETC. Occidental and NGO agree that, for the period from the Closing
Date until six years after the Closing Date:

         (a)     NGO shall maintain in effect without reduction in scope or
coverage the indemnification provisions for present and former directors,
officers and employees of NGO contained in NGO's certificate of incorporation
and by-laws, in each case as in effect on the Closing Date; and

         (b)     In the event that NGO transfers all or substantially all of
its properties and assets to any other Person, proper provision shall be made
so that such Person shall assume the obligations of NGO under this Section
12.7.





                                       56
<PAGE>   64





         Section 12.8     NOTICES.  All notices and other communications under
this Agreement shall be in writing and sent by (i) personal delivery (including
courier service), (ii) telecopier during normal business hours to the number
indicated below, or (iii) first class or registered or certified mail, postage
prepaid and addressed as follows (or to such other addresses and telecopier
numbers as any Party may designate by notice to the other Parties) (any
communication being deemed given upon receipt):

         IF TO H&P, AT:

         Helmerich & Payne, Inc.
         1579 E. 21st Street
         Tulsa, Oklahoma 74114
         Attention:   President
         Telecopier No.: (918) 743-2671

         WITH A COPY TO:

         General Counsel
         1579 E. 21st Street
         Tulsa, Oklahoma 74114
         Telecopier No.: (918) 743-2671;

         IF TO NGO, AT:

         Natural Gas Odorizing, Inc.
         3601 Decker Drive
         Baytown, Texas 77520
         Telecopier No.: (713) 424-3681;

         IF TO THE OCCIDENTAL OR THE COMPANY, AT:

         Occidental Petroleum Corporation
         10889 Wilshire Boulevard
         Los Angeles, California 90024
         Attention:   General Counsel
         Telecopier No.: (310) 443-6333.

         Section 12.9     AMENDMENTS AND WAIVERS.

         (a)     Except as set forth in Section 12.9(b) and subject to the
provisions of Title 18, Section 1081D.1. of the OGCA, no amendment of any
provision of this Agreement shall be valid unless the same shall be set forth
in an instrument in writing signed by each Party.  Each of the Parties may
waive (i) any inaccuracies in the representations and warranties of any other
Party contained in this Agreement or in any document, certificate or





                                       57
<PAGE>   65




writing delivered pursuant hereto, or (ii) compliance by such other Party with
any of the agreements of such Party or the fulfillment of any of the conditions
to its own obligations set forth herein.  Any agreement on the part of any
Party to any such waiver shall be valid only if set forth in an instrument in
writing signed by such Party.  No waiver by any Party of any default,
misrepresentation or breach of warranty or covenant hereunder, whether
intentional or not, shall be deemed to extend to any prior or subsequent
default, misrepresentation or breach of warranty or covenant hereunder or
affect in any way any rights arising by virtue of any such occurrence.  Neither
the failure nor any delay by any Party in exercising any right, power or
privilege under this Agreement will operate as a waiver of such right, power or
privilege, and no single or partial exercise of any such right, power or
privilege will preclude any other or further exercise of such right, power or
privilege or the exercise of any other right, power or privilege.

         (b)     H&P may deliver to the other Parties, prior to the Closing
Date, a written amendment of any one or more of the Schedules (other than
Schedules 1-A, 3.2, 3.6 (except with respect to any Order), 3.22, 3.24 (except
with respect to condemnation, eminent domain or similar Proceedings, or
litigation), 3.26.1, 3.26.2, 3.26.3, 4.3, 5.2, 6.7 and 7.4) to disclose the
occurrence of any event prior to the Closing Date (whether such event shall
have occurred before or after the date of this Agreement), and each such
amendment shall be effective for all purposes under this Agreement on and as of
(and, for purposes of Article X, prior to) the Closing Date; provided, however,
that no such amendment shall be effective for any purpose whatsoever if (i)
such amendment shall not have been delivered in draft form to such Parties for
review not less than two Business Days prior to the Closing Date, (ii) such
amendment shall not state when the event or events so disclosed by such
amendment shall have occurred, or (iii) such amendment shall disclose the
occurrence of any event which shall constitute a breach of Article V.

         Section 12.10    ASSIGNMENT; SUCCESSORS AND ASSIGNS.   This Agreement
shall be binding upon, and inure to the benefit of, the Parties and their
respective successors and permitted assigns, but neither this Agreement nor any
of the rights, interests or obligations hereunder shall be assigned, by
operation of law or otherwise, by any Party without the prior written consent
of the other Parties; provided, however, that, notwithstanding the foregoing,
Occidental may assign this Agreement or its rights hereunder to any wholly
owned subsidiary of Occidental provided that (i), prior to any such assignment,
the Person to which such assignment shall be made shall expressly assume by an
instrument in writing, executed and delivered to the other Parties, the
performance and observance of every obligation, covenant and agreement in this
Agreement on the part of Occidental to be performed or observed, and (ii) no
such assignment shall have the effect of releasing Occidental or any other
Person (including any additional party) from its obligations, covenants or
agreements under this Agreement.

         Section 12.11    PAYMENTS.  All payments, if any, by H&P, Occidental
or any Affiliate of either thereof pursuant to any of the provisions of this
Agreement shall be made by wire transfer of immediately available funds to a
bank account of H&P or Occidental, as the case may be, at the respective banks
used by H&P and Occidental, the





                                       58
<PAGE>   66




name of which bank and the number of which account shall be furnished by H&P to
Occidental, and by Occidental to H&P, not later than one Business Day prior to
the Closing Date (or at such other bank or account as H&P or Occidental may
designate after the Closing Date by notice to H&P or Occidental, as the case
may be).

         Section 12.12    SEVERABILITY.  Any provision of this Agreement which
is prohibited or unenforceable in any jurisdiction shall, as to such
jurisdiction, be ineffective to the extent of such prohibition or
unenforceability without invalidating the remaining provisions hereof or
affecting the validity or enforceability of such provision in any other
jurisdiction.

         Section 12.13    HEADINGS.  The Table of Contents and the Index to
Schedules and Exhibits set forth in, and the descriptive headings of the
several Articles and Sections of, this Agreement are inserted for convenience
only and do not constitute a part of this Agreement.

         Section 12.14    GOVERNING LAW.  This Agreement shall be governed by,
and construed in accordance with, the laws of the State of Oklahoma, without
regard to principles of conflicts of law.

         Section 12.15    COUNTERPARTS.  This Agreement may be executed in one
or more counterparts, each of which when so executed shall be deemed an
original, but all of which together shall constitute one and the same
instrument.

         Section 12.16    CONSTRUCTION.  The Parties have participated jointly
in the negotiation and drafting of this Agreement.  In the event any ambiguity
or question of intent or interpretation arises, this Agreement shall be
construed as if drafted jointly by the Parties, and no presumption or burden of
proof shall arise favoring or disfavoring any Party by virtue of the authorship
of any of the provisions of this Agreement.  Personal pronouns, when used in
this Agreement, whether in the masculine, feminine or neuter gender, shall
include all other genders, and the singular shall include the plural, and vice
versa.  All references in this Agreement or in any Schedule attached hereto to
(i) Articles, Sections or subsections shall refer to the corresponding Article,
Section or subsection of this Agreement, unless specific reference is made to
an Article or a Section or subsection of another document or instrument, and
(ii) a Schedule or an Exhibit shall refer to the corresponding Schedule or
Exhibit to this Agreement, unless specific reference is made to a Schedule or
an Exhibit to another document or instrument.  Any reference in this Agreement
to any Law shall be deemed also to refer to all rules and regulations
promulgated thereunder, unless the context requires otherwise.  The word
"including" shall mean "including, without limitation,".

         Section 12.17    INCORPORATION OF EXHIBITS AND SCHEDULES.  The
Exhibits and Schedules identified in this Agreement are incorporated herein by
reference and made a part hereof.





                                       59
<PAGE>   67




         IN WITNESS WHEREOF, the Parties have executed and delivered this
Agreement as of the date first written above.


                                  OCCIDENTAL PETROLEUM CORPORATION



                                  By:       STEPHEN I. CHAZEN
                                      --------------------------------
                                      Name:   Stephen I. Chazen
                                      Title:  Executive Vice President -
                                              Corporate Development


[Corporate Seal]

ATTEST:


      MATTHEW T. GAY
- ----------------------------
Name:   Matthew T. Gay
Title:  Assistant Secretary



                                  OPC ACQUISITION CORP.



                                  By:       STEPHEN I. CHAZEN
                                      --------------------------------
                                      Name:   Stephen I. Chazen
                                      Title:  President



[Corporate Seal]

ATTEST:


      MATTHEW T. GAY
- ----------------------------
Name:   Matthew T. Gay
Title:  Assistant Secretary





                                       60
<PAGE>   68





                                  HELMERICH & PAYNE, INC.



                                  By:          HANS HELMERICH
                                      --------------------------------
                                      Name:   Hans Helmerich
                                      Title:  President

[Corporate Seal]

ATTEST:


      STEVEN R. MACKEY
- ----------------------------
Name:   Steven R. Mackey
Title:  Secretary





                                  NATURAL GAS ODORIZING, INC.



                                  By:        JEROME T. JOHNSON
                                      --------------------------------
                                      Name:   Jerome T. Johnson
                                      Title:  President

[Corporate Seal]

ATTEST:


        KAREN ELLIOT
- ----------------------------
Name:   Karen Elliott
Title:  Assistant Secretary





                                       61
<PAGE>   69
                                                                       Exhibit A



                             CERTIFICATE OF MERGER

                                       OF

                             OPC ACQUISITION CORP.

                                 WITH AND INTO

                          NATURAL GAS ODORIZING, INC.

                           UNDER SECTION 1081 OF THE
                        OKLAHOMA GENERAL CORPORATION ACT



TO THE SECRETARY OF STATE OF THE STATE OF OKLAHOMA:

      The undersigned Surviving Corporation, Natural Gas Odorizing, Inc., an
Oklahoma corporation, hereby certifies:

      1 .        The names of the constituent corporations merged and the names
of the states under the laws of which such corporations are incorporated are:

<TABLE>
<CAPTION>
                                                              State of
                   Name of Corporation                      Incorporation
                   -------------------                      -------------
                 <S>                                           <C>

                 Natural Gas Odorizing, Inc.                   Oklahoma
                 OPC Acquisition Corp.                         Oklahoma.
</TABLE>

         2.      An Agreement and Plan of Merger (the "Agreement of Merger")
has been approved, adopted, certified, executed and acknowledged by each of the
constituent corporations in accordance with the provisions of Section 1081 of
the Oklahoma General Corporation Act.

         3.      The name of the Surviving Corporation is: Natural Gas
Odorizing, Inc.

         4.      The Certificate of Incorporation of the Surviving Corporation
shall be the Certificate of Incorporation of Natural Gas Odorizing, Inc.
<PAGE>   70
         5.      The executed Agreement of Merger is on file at the principal
place of business of the Surviving Corporation at the following address:

                 Occidental Tower
                 5005 LBJ Freeway
                 Dallas, Texas 75244.

         6.      A copy of the Agreement of Merger will be furnished by the
Surviving Corporation, on request and without cost, to any shareholder of any
constituent corporation.

         IN WITNESS WHEREOF, Natural Gas Odorizing, Inc., an Oklahoma
corporation, as the Surviving Corporation, has caused this Certificate of
Merger to be executed in its name by [its President] [one of its Vice
Presidents] and attested by [its Secretary] [one of its Assistant Secretaries]
this ______ day of __________ , 1996.



                                        Natural Gas Odorizing, Inc.,
                                        an Oklahoma corporation


                                        By:
                                            ------------------------------------
                                            Name:
                                            Title:  [President] [Vice President]




ATTEST:


- --------------------------
Name:
Title: [Secretary] [Assistant Secretary]





                                       2
<PAGE>   71
                                                                       EXHIBIT B



                               NOVATION AGREEMENT

                          entered into by and between

            NATIONAL UNION FIRE INSURANCE COMPANY OF PITTSBURGH, PA.

                       (hereinafter called the "Company")

                                      and

                            HELMERICH & PAYNE, INC.
                           (hereinafter called "H&P")

                                      and

                        OCCIDENTAL PETROLEUM CORPORATION
                       (hereinafter called "Occidental")



         WHEREAS, the Company and H&P have previously entered into the 
following Agreements:


         1.      Indemnity Agreement effective September 30, 1985;
         2.      Indemnity Agreement effective September 30, 1986;
         3.      Indemnity Agreement effective September 30, 1987;
         4.      Indemnity Agreement effective September 30, 1988;
         5.      Indemnity Agreement effective September 30, 1989;
         6.      Indemnity Agreement effective September 30, 1990;
         7.      Indemnity Agreement effective September 30, 1993; and


         WHEREAS, the Indemnity Agreements listed in 1-7 above and any Addenda
and Policy and Funding Schedule(s) thereto are hereinafter collectively called
the "Indemnity Agreements"; and

         WHEREAS, under this Novation Agreement, H&P desires that it be
replaced as the Client (Indemnitor) under the Indemnity Agreements, with
respect to losses and expenses of its subsidiary, Natural Gas Odorizing, Inc.,
the said losses and expenses as to which H&P is to be replaced being herein
collectively called the "Subject Losses";

         WHEREAS, H&P desires to be fully released and discharged by the
Company from its obligations and liabilities under the Indemnity Agreements
with respect to the
<PAGE>   72
Subject Losses relating to H&P's subsidiary company, Natural Gas Odorizing,
Inc.; and

         WHEREAS, Occidental, a company organized and doing business under the
laws of the State of Delaware, desires to replace H&P as the Client
(Indemnitor) under the Indemnity Agreements, with respect to the Subject Losses
only; and

         WHEREAS, the Company consents to and accepts the replacement of H&P by
Occidental as to the Subject Losses as described above.

         NOW, THEREFORE, in consideration of the premiums paid and the mutual
covenants contained herein the parties hereto do mutually agree as follows:

         1.      This Agreement shall take effect as of the Closing (as defined
in the Agreement and Plan of Merger between Occidental, OPC Acquisition
Corporation, H&P and Natural Gas Odorizing, Inc.) (               , 1996,
hereinafter called the "Effective Time"). H&P transfers, delegates, conveys and
assigns to Occidental, all its rights, duties, obligations and interests as
Client (Indemnitor) under the Indemnity Agreements with respect to the Subject
Losses.  Occidental agrees to accept, assume, undertake and perform all rights,
duties and obligations as Client (Indemnitor) under the Indemnity Agreements
with respect to the Subject Losses;

                 (i)      as if it were originally the Client (Indemnitor)
         under the Indemnity Agreements as to such Subject Losses and

                 (ii)     regardless of whether the Subject Losses or the
         rights, duties and obligations of the Client (Indemnitor) arose before
         or after the Effective Time of this Novation Agreement.

         2.      Upon the Effective Time, H&P is released and fully discharged
from any and all obligations and liabilities under the Indemnity Agreements
with respect to the Subject Losses only; it being expressly agreed that as of
the Effective Time of this Novation Agreement and thereafter, the Company shall
look solely to Occidental as its Client (Indemnitor) under the Indemnity
Agreements with respect to the Subject Losses regardless of whether the Subject
Losses were incurred or attributable to times before or after the Effective
Time.

         3.      In consideration of the Subject Losses assumed by Occidental
herein, the Company hereby releases and discharges H&P, its subsidiaries and
their respective directors, officers, employees and shareholders, from all
present and future claims, costs, damages, penalties, demands, attorneys' fees,
liabilities and obligations to the Company of whatsoever character, arising out
of the Indemnity Agreements but only with respect to the Subject Losses,
regardless of whether such loss, claims or liability were incurred or
attributed


                                      -2-
<PAGE>   73
to times before or after the Effective Time. H&P shall otherwise remain liable
to the Company under the Indemnity Agreements.

         4.      The Company hereby represents and warrants that the list of
Indemnity Agreements set forth in the first and second WHEREAS clauses of this
Novation Agreement comprises a complete schedule of all such agreements
executed by the Company and H&P between September 30th 1985 and the Effective
Time.

         5.      This Novation Agreement may be executed in counterparts each
of which shall be treated as an original and to form one and the same document.

         6.      The terms of the Indemnity Agreements, except as amended
herein, remain unchanged and in full force and effect.

         7.      This Novation Agreement shall be binding on the successors and
assigns of the parties hereto.

         8.      This Novation Agreement shall be governed by, and construed in
accordance with, the laws of the State of New York, without regard to
principles of conflicts of law.

         9.      The parties hereto recognize that not later than thirty (30)
days after the Effective Time, Occidental will provide a Letter of Credit in
favor of the Company to secure Occidental's obligations assumed hereunder. Such
Letter of Credit will be issued and delivered to the Company in an amount and
form as required by the Company, and from a bank acceptable to the Company. Not
later than sixty (60) days after the Effective Time, Occidental will also
provide the Company with Promissory Notes (in accordance with the Indemnity
Agreements) in the amounts required by the Company to reflect the obligations
assumed by Occidental hereunder.





                                      -3-
<PAGE>   74
                 IN WITNESS WHEREOF, the Company, H&P and Occidental have
caused this Agreement to be executed by their duly authorized representatives
on the date indicated below.



Dated:
      --------------------

                                NATIONAL UNION FIRE INSURANCE
                                COMPANY OF PITTSBURGH, PA.


                                By:
                                   --------------------------------------

                                Its:
                                    -------------------------------------


                                HELMERICH & PAYNE, INC.           
                                                                  
                                                                  
                                By:                               
                                   --------------------------------------
                                                                  
                                Its:                              
                                    -------------------------------------
                                                                  
                                                                  
                                OCCIDENTAL PETROLEUM CORPORATION  
                                                                  
                                                                  
                                By:                               
                                   --------------------------------------

                                Its:                              
                                    --------------------------------------




                                      -4-
<PAGE>   75
                                                                       Exhibit C



                             REGISTRATION AGREEMENT

         REGISTRATION AGREEMENT ("Agreement"), dated as of ____________ , 1996,
between OCCIDENTAL PETROLEUM CORPORATION, a Delaware corporation ("Occidental"),
and HELMERICH & PAYNE, INC., a Delaware corporation ("H&P").

         WHEREAS, pursuant to and subject to the terms and conditions of an
Agreement and Plan of Merger, dated as of August 23, 1996 (the "Merger
Agreement"), Occidental is acquiring Natural Gas Odorizing Inc., an Oklahoma
corporation, from H&P; and

         WHEREAS, in connection with the transactions contemplated by the
Merger Agreement, H&P is receiving ____ shares (the "Shares") of Common Stock, 
par value $.20 per share, of Occidental ("Occidental Common Stock") which are
"restricted securities" as defined in Rule 144 under the Securities Act of 1933,
as amended (the "Act"), and Occidental has agreed, subject to the terms and
conditions contained in the Merger Agreement, to execute and deliver this
Agreement;

         NOW, THEREFORE, in consideration of the premises and of the mutual
agreements and covenants hereinafter set forth, the parties hereto agree as
follows:

         1.      Registration.

                 (a)      In consideration of H&P's willingness to accept the
Shares pursuant to the Merger Agreement, and subject to the performance by H&P
of its covenants set forth herein, Occidental (i) shall prepare and file within
15 days following the Closing Date (as such term is defined in the Merger
Agreement) with the Securities and Exchange Commission (the "Commission") a
registration statement on Form S-3 (the "Registration Statement") with respect
to the offering and sale of the Shares by H&P on a delayed or continuous basis
pursuant to Rule 415 under the Act, and (ii) shall use diligent efforts to
cause the Registration Statement to become effective as soon as possible after
the filing thereof so as to permit the secondary resale of the Shares by H&P.
As used herein, the term "Registration Statement" means the Registration
Statement, including exhibits and financial statements and schedules and
documents incorporated by reference therein, as amended, when it becomes
effective under the Act and, in the case of the references to the Registration
Statement as of a date subsequent to the effective date, as amended or
supplemented as of such date. As used herein, the term "Prospectus" means the
prospectus included in the Registration Statement as of the date it becomes
effective under the Act and, in the case of references to the Prospectus as of
a date subsequent to the effective date of the Registration Statement, as
amended or supplemented as of such date, including all documents incorporated
by reference therein, as amended, and each prospectus supplement relating to
the offering and sale of any of the Shares. At least five days prior to filing
with the Commission the Registration Statement or Prospectus or any supplements
or






<PAGE>   76
amendments thereto, Occidental shall furnish draft copies thereof (excluding
the documents incorporated by reference therein) to H&P for its review.

                 (b)      Occidental will use its diligent efforts to cause the
Registration Statement to remain effective, and to file with the Commission
such amendments and supplements as may be necessary to keep the Prospectus
current and in compliance in all material respects with the Act, until the
earlier to occur of the following: (i) the date on which restrictions on sales
of the Shares by H&P would otherwise terminate pursuant to Rule 144(k) under
the Act (as such rule or any successor rule shall be amended from time to
time); or (ii) the sale of all of the Shares covered by the Registration
Statement, whether pursuant to the Registration Statement or otherwise.
Notwithstanding the foregoing, Occidental shall not be required to keep the
Registration Statement effective, and H&P shall not distribute any Shares
pursuant thereto, if in the written opinion of counsel to Occidental addressed
to H&P, the Shares may be sold by H&P without registration or restriction. If
the Registration Statement ceases to be effective for any reason at any time
after it is first declared effective by the Commission (other than because of
the sale of all of the Shares registered thereunder), Occidental shall use its
diligent efforts to obtain the prompt withdrawal of any order suspending the
effectiveness thereof, and in any event shall, within 30 days after such
cessation of effectiveness, amend the Registration Statement in a manner
reasonably expected to obtain the withdrawal of the order suspending the
effectiveness thereof.

                 (c)      Occidental shall furnish to H&P a conformed copy of
the Registration Statement as declared effective by the Commission and of each
post-effective amendment thereto, and such number of copies of the final
Prospectus and of each post-effective amendment or supplement thereto as may
reasonably be required to facilitate the distribution of the Shares. Promptly
after the Registration Statement has been declared effective by the Commission,
Occidental shall furnish to H&P a copy of the Commission's order to that
effect. Thereafter, in the event that any stop order suspending the
effectiveness of the Registration Statement is issued or any proceedings for
that purpose are instituted or threatened by the Commission, Occidental will
promptly so notify H&P.

                 (d)      The Registration Statement shall be prepared by
Occidental in accordance with the Act and the rules and regulations promulgated
thereunder. The section of the Prospectus entitled "Selling Stockholder" shall
be prepared in accordance with the requirements of Item 507 of Regulation S-K
promulgated by the Commission ("Regulation S-K") and shall be based upon the
information provided by H&P to Occidental pursuant to Section 3(a). The section
of the Prospectus entitled "Plan of Distribution" shall be prepared in
accordance with the requirements of Item 508 of Regulation S-K and shall
provide that H&P may distribute the Shares pursuant to the Registration
Statement from time to time in one or more transactions on the New York Stock
Exchange, including block trades, in negotiated transactions or in a
combination of any such methods of sale.

                 (e)      Promptly after having been notified by H&P of its
intention to distribute Shares in a manner described by the Registration
Statement in the section entitled "Plan of





                                      -2-
<PAGE>   77
Distribution" and after having received the information required to be
delivered to Occidental as provided in Section 3(c), Occidental will, if
necessary, (i) prepare a supplement to the Prospectus based upon the
information so provided and file the same with the Commission pursuant to Rule
424(b) under the Act and (ii) register or qualify the Shares to be sold under
the securities or blue sky laws of such jurisdictions in the United States as
H&P shall reasonably request; provided, however, that Occidental shall in no
event be required to qualify to do business as a foreign corporation or as a
dealer in any jurisdiction where it is not so qualified, to conform its
capitalization or the composition of its assets at the time to the securities
or blue sky laws of any such jurisdiction, to execute or file any general
consent to service of process under the laws of any jurisdiction, to take any
action that would subject it to service of process in suits other than those
arising out of the offer and sale of Shares, or to subject itself to taxation
in any jurisdiction where it has not therefore done so.

         2.      Expenses of Registration. All expenses in connection with the
Registration Statement, any qualification or compliance with federal or state
laws required in connection therewith, and the distribution of the Shares shall,
as between H&P and Occidental, be borne as follows:

                 (a)      Occidental shall pay and be responsible for all fees
and expenses incident to the performance of its obligations hereunder,
including without limitation the registration fee payable under the Act, blue
sky fees and expenses, if applicable (subject to the limitations set forth in
Section 1(e)), all fees and disbursements of Occidental's counsel and
accountants, and the cost of printing or photocopying the Registration
Statement and the Prospectus. Occidental will not be required to engage the
services of a printer with respect to the Registration Statement or the
Prospectus, but may elect to do so.

                 (b)      H&P shall pay all fees and disbursements of its own
counsel and advisers, all stock transfer fees (including the cost of all
transfer tax stamps) or expenses, if any, and all other expenses (including
brokerage discounts, commissions and fees) related to the distribution of the
Shares that have not expressly been assumed by Occidental.

         3.      H&P's Covenants Regarding the Shares. H&P covenants and agrees
with Occidental that:


                 (a)      H&P will cooperate with Occidental in connection with
the preparation of the Registration Statement, and for so long as Occidental is
obligated to keep the Registration Statement effective, H&P will provide to
Occidental, in writing, for use in the Registration Statement, all information
regarding H&P and such other information as may be necessary to enable
Occidental to prepare the Registration Statement and Prospectus covering the
Shares and to maintain the effectiveness thereof.

                 (b)      During such time as H&P may be engaged in a
distribution of the Shares, H&P will comply with Rules 10b-2, 10b-6 and 10b-7
promulgated under the Securities





                                      -3-
<PAGE>   78
Exchange Act of 1934, as amended (the "Exchange Act") and pursuant thereto
will, among other things: (i) not engage in any stabilization activity in
connection with the securities of Occidental in contravention of such Rules;
(ii) distribute the Shares solely in the manner described in the Prospectus;
(iii) cause to be furnished to each agent or broker-dealer to or through whom
the Shares may be offered, or to the offeree if an offer is made directly by
H&P, such copies of the Prospectus (as amended and supplemented to such date)
and documents incorporated by reference therein as may be required by such
agent, broker-dealer or offeree or applicable law; and (iv) not bid for or
purchase any securities of Occidental or attempt to induce any person to
purchase any securities of Occidental other than as permitted under the
Exchange Act.

                 (c)      At least five days prior to any distribution of the
Shares, H&P will advise Occidental in writing of the dates on which the
distribution will commence and terminate, the number of the Shares to be sold,
the name of any agent or broker-dealer to or through whom such distribution is
being made, the selling commission or other compensation to such agent or
broker-dealer and the number of shares of Occidental Common Stock that will be
owned beneficially by H&P after giving effect to such sale.

                 (d)      Upon notice requiring the suspension of the
distribution of any of the Shares pursuant to the provisions of Section 4, then
H&P shall cease distributing the Shares until such time as Occidental or the
managing underwriter or underwriters notify H&P that distribution of the Shares
may recommence.

                 (e)      H&P will not sell, transfer or dispose of any of the
Shares, or enter into any agreements or understandings with third parties
respecting the sale, transfer or disposition of any of the Shares, except as
described in the section of the Prospectus entitled "Plan of Distribution" so
long as Occidental maintains the effectiveness of the Registration Statement.

         4.      Suspension of the Distribution of the Shares.

                 (a)      If Occidental determines in good faith that the
distribution of any of the Shares would interfere with any pending financing,
acquisition, corporate reorganization or any other corporate development
involving Occidental or any of its subsidiaries or would require premature
disclosure thereof, and promptly gives H&P written notice of such
determination, Occidental shall be entitled to require H&P to suspend its
distribution of the Shares for a reasonable period of time which, for purposes
of this Section 4(a), shall not exceed 60 days. Such written notice shall
contain a general statement of the reasons for such suspension and an estimate
of the anticipated period of suspension, and Occidental shall promptly notify
H&P of the expiration or earlier termination of such suspension.  Following the
expiration or termination of any such suspension, Occidental shall not be
entitled to impose another suspension pursuant to this Section 4(a) for at
least 30 days.

                 (b)      If Occidental shall file a registration statement
with respect to an offering through an underwriter or group of underwriters of
Occidental Common Stock or securities





                                      -4-
<PAGE>   79
convertible into or exchangeable or exercisable for Occidental Common Stock, and
the managing underwriter or underwriters advise Occidental that a sale or
distribution of the Shares would adversely affect such offering, then upon
written notice by or on behalf of such underwriters, H&P shall, to the extent
not inconsistent with applicable law, suspend the distribution of any of the
Shares during the 10-day period prior to and the 90-day period following the
effective date of such registration statement, with such 90-day period being
subject to early termination by the managing underwriter or underwriters.
Following the expiration or termination of any such suspension, no other
suspension may be imposed pursuant to this Section 4(b) for at least 30 days.

         5.      Indemnification.

                 (a)      Occidental will indemnify and hold harmless H&P, its
directors and officers and each person, if any, who controls H&P within the
meaning of either Section 15 of the Act or Section 20 of the Exchange Act
(collectively, the "H&P Indemnified Parties") from and against any losses,
claims, damages or liabilities, joint or several, to which the H&P Indemnified
Parties may become subject, insofar as such losses, claims, damages or
liabilities (or actions in respect thereof) are based upon any untrue statement
or alleged untrue statement of a material fact contained in the Registration
Statement or the Prospectus, or any omission or alleged omission to state
therein a material fact required to be stated therein or necessary to make the
statements therein, in light of the circumstances under which they were made,
not misleading; and, subject to Section 5(c), Occidental will reimburse the H&P
Indemnified Parties for any legal or other expense reasonably incurred by them
in connection with investigating or defending any such loss, claim, damage or
liability; provided. however, that Occidental will not indemnify or hold
harmless any H&P Indemnified Party from or against any such loss, claim,
damage, liability or expense (i) that arises out of or is based upon any
violation of H&P's covenants in Section 3 or of any federal or state securities
laws, rules or regulations committed by any of the H&P Indemnified Parties (or
any agent, broker-dealer or underwriter engaged by them) or (ii) if the untrue
statement, omission or allegation thereof upon which such losses, claims,
damages, liabilities or expenses are based (x) was made in reliance upon and in
conformity with the information provided by H&P specifically for use or
inclusion in the Registration Statement, or (y) was made in any Prospectus used
after such time as Occidental advised H&P that the filing of a post-effective
amendment or supplement thereto was required, except the Prospectus as so
amended or supplemented, or (z) was made in any Prospectus used after such time
as the obligation of Occidental hereunder to keep the Registration Statement
effective and current has expired.

                 (b)      H&P will indemnify and hold harmless Occidental, its
directors and officers and each person, if any, who controls Occidental within
the meaning of either Section 15 of the Act or Section 20 of the Exchange Act
(collectively, the "Occidental Indemnified Parties"), from and against any
losses, claims, damages or liabilities, joint or several, to which the
Occidental Indemnified Parties may become subject, insofar as such losses,
claims, damages or liabilities (or actions in respect thereof) arise out of or
are based upon (i) any untrue statement or alleged untrue statement of a
material fact contained in the Registration Statement or the Prospectus, or any
omission or alleged omission to state therein a material fact required to be
stated therein or necessary





                                      -5-
<PAGE>   80
to make the statements therein, in light of the circumstances under which they
were made, not misleading, if the statement or omission was made in reliance
upon and in conformity with the information provided by H&P specifically for
use or inclusion in the Registration Statement, or (ii) the use of any
Prospectus after such time as Occidental has advised H&P that the filing of a
post-effective amendment or supplement thereto is required, except the
Prospectus as so amended or supplemented, or (iii) the use of any Prospectus
after such time as the obligation of Occidental hereunder to keep the
Registration Statement effective and current has expired, or (iv) any violation
by H&P, its directors or officers or any person who controls H&P within the
meaning of either Section 15 of the Act or Section 20 of the Exchange Act (or
any agent, broker-dealer or underwriter engaged by H&P or any such controlling
person) of H&P's covenants in Section 3 or of any federal or state securities
law or rule or regulation thereunder; and, subject to Section 5(c), H&P will
reimburse the Occidental Indemnified Parties for any legal or other expenses
reasonably incurred by them in connection with investigating or defending any
such loss, claim, damage or liability.

                 (c)      Each party entitled to indemnification under this
Section 5 (the "Indemnified Party") shall give notice to the party required to
provide indemnification (the "Indemnifying Party") promptly after such
Indemnified Party has actual knowledge of any claim as to which indemnity may
be sought, and the Indemnifying Party may participate at its own expense in the
defense or, if it so elects, to assume the defense of any such claim and any
action or proceeding resulting therefrom, including the employment of counsel
and the payment of all expenses. The failure of any Indemnified Party to give
notice as provided herein shall not relieve the Indemnifying Party from its
obligations to indemnify such Indemnified Party, except to the extent that the
Indemnified Party's failure to so notify actually prejudices the Indemnifying
Party's ability to defend against such claim, action or proceeding; it being
understood and agreed that the failure to so notify the Indemnifying Party
prior to the execution of a binding settlement agreement or the entry of a
judgment or issuance of an award with respect to a claim, action or proceeding
shall constitute actual prejudice to the Indemnifying Party's ability to defend
against such claim, action or proceeding. In the event that the Indemnifying
Party elects to assume the defense in any action or proceeding, the Indemnified
Party shall have the right to employ separate counsel in any such action or
proceeding and to participate in the defense thereof, but the fees and expenses
of such separate counsel shall be such Indemnified Party's expense unless (i)
the Indemnifying Party has agreed to pay such fees and expenses or (ii) the
named parties to any such action or proceeding (including any impleaded
parties) include an Indemnified Party and the Indemnifying Party, and such
Indemnified Party shall have been advised by counsel that there may be a
conflict of interest between such Indemnified Party and the Indemnifying Party
in the conduct of the defense of such action (in which case, if such
Indemnified Party notifies the Indemnifying Party that it elects to employ
separate counsel at the expense of the Indemnifying Party, the Indemnifying
Party shall not assume the defense of such action or proceeding on such
Indemnified Party's behalf, it being understood, however, that the Indemnifying
Party shall not, in connection with any one such action or proceeding or
separate but substantially similar or related actions or proceedings arising
out of the same general allegations or circumstances, be liable for the
reasonable fees and expenses of more than one separate firm of attorneys at any
time for all Indemnified Parties, which firm shall be designated in writing by
H&P or Occidental, as the case may be). No Indemnifying Party, in the defense
of any such claim or litigation, shall, except with the





                                      -6-
<PAGE>   81
consent of the Indemnified Party, consent to entry of any judgment or enter
into any settlement which does not include as an unconditional term thereof the
giving by the claimant or plaintiff to such Indemnified Party of a release from
all liability in respect to such claim or litigation. The Indemnifying Party
shall not be liable for any settlement of any such action or proceeding
effected without its written consent, but if settled with its written consent
or, if there be a final judgment for the plaintiff in any such action or
proceeding, the Indemnifying Party shall indemnify and hold harmless the
Indemnified Party from and against any loss or liability by reason of such
settlement or judgment.

                 (d)      If the indemnification provided for under this
Section 5 is unavailable to or insufficient to hold the Indemnified Party
harmless under subparagraphs (a) or (b) above in respect of any losses, claims,
damages or liabilities referred to therein for any reason other than as
specified therein, then the Indemnifying Party shall contribute to the amount
paid or payable by such Indemnified Party as a result of such losses, claims,
damages or liabilities in such proportion as is appropriate to reflect the
relative fault of the Indemnifying Party on the one hand and such Indemnified
Party on the other in connection with the statements or omissions which
resulted in such losses, claims, damages or liabilities, as well as any other
relevant equitable considerations. The relative fault shall be determined by
reference to, among other things, whether the untrue or alleged untrue
statement of a material fact or the omission or alleged omission to state a
material fact relates to information supplied by (or omitted to be supplied by)
Occidental or H&P, the parties' relative intent, knowledge, access to
information and opportunity to correct or prevent such statement or omission,
the relative benefits received by each party from the sale of the Shares and
any other equitable considerations appropriate under the circumstances. The
amount paid or payable by an Indemnifying Party as a result of the losses,
claims, damages or liabilities referred to above in this Section 5(d) shall be
deemed to include any legal or other expenses reasonably incurred by such
Indemnified Party in connection with investigating or defending any such action
or claim. Notwithstanding the foregoing provisions of this Section 5(d), H&P
shall not be required to contribute pursuant to this Section 5(d) any amount in
excess of the amount by which the proceeds received by H&P from the sale of the
Shares in the transaction on which such action or claim is based exceeds the
amount of any damages H&P has otherwise been required to pay by reason of an
untrue or alleged untrue statement or omission or alleged omission.  No person
guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of
the Act) shall be entitled to contribution from any person who was not guilty
of such fraudulent misrepresentation.

         6.      No Third-Party Beneficiaries.     NOTHING CONTAINED IN THIS
AGREEMENT, EXPRESS OR IMPLIED, IS INTENDED TO CONFER UPON ANY PERSON, OTHER
THAN THE PARTIES AND THEIR RESPECTIVE SUCCESSORS AND PERMITTED ASSIGNS, ANY
RIGHTS, REMEDIES OR OBLIGATIONS UNDER, OR BY REASON OF, THIS AGREEMENT.

         7.      Entire Agreement.      This Agreement constitutes the entire
agreement between the parties, and supersedes all prior understandings and
agreements, with respect to the subject matter hereof or thereof





                                      -7- 
<PAGE>   82
         8.      Notices. All notices and other communications under this
Agreement shall be in writing and sent by (i) personal delivery (including
courier service), (ii) telecopier during normal business hours to the number
indicated below, or (iii) first class or registered or certified mail, postage
prepaid and addressed as follows (or to such other addresses and telecopier
numbers as either party may designate by notice to the other party) (any
communication being deemed given upon receipt):

                 If to H&P at:

                 Helmerich & Payne, Inc.
                 1579 E. 21st Street
                 Tulsa, Oklahoma 74114
                 Attention: President
                 Telecopier No.: (918) 743-2671

                 With a copy to:

                 General Counsel
                 1579 E. 21st Street
                 Tulsa, Oklahoma 74114
                 Telecopier No.: (918) 743-2671

                 If to Occidental at:

                 Occidental Petroleum Corporation
                 10889 Wilshire Boulevard
                 Los Angeles, California 90024
                 Attention: General Counsel
                 Telecopier No.: (310) 443-6333

         9.      Amendments and Waivers. No amendment of any provision of this
Agreement shall be valid unless the same shall be set forth in an instrument in
writing signed by each party. Each party may waive compliance by the other
party with any agreements of such party or the fulfillment of any of the
conditions to its own obligations set forth herein.  Any agreement on the part
of any party to any such waiver shall be valid only if set forth in an
instrument in writing signed by such party. No waiver by either party of any
default, misrepresentation or breach of covenant hereunder, whether intentional
or not, shall be deemed to extend to any prior or subsequent default,
misrepresentation or breach of covenant hereunder or affect in any way any
rights arising by virtue of any prior or subsequent such occurrence. Neither
the failure nor any delay by any party in exercising any right, power or
privilege under this Agreement will operate as a waiver of such right, power or
privilege, and no single or partial exercise of any such right, power or
privilege will preclude any other or further exercise of such right, power or
privilege or the exercise of any other right, power or privilege.


                                      -8- 
<PAGE>   83
         10.     Assignment: Successors and Assigns. This Agreement shall be
binding upon, and inure to the benefit of, the parties and their respective
successors and permitted assigns, but neither is Agreement nor any of the
rights, interests or obligations hereunder shall be assigned, by operation of
law or otherwise, by any party without the prior written consent of the other
party.

         11.     Severability. Any provision of this Agreement which is
prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction,
be ineffective to the extent of such prohibition or unenforceability without
invalidating the remaining provisions hereof or affecting the validity or
enforceability of such provision in any other jurisdiction.

         12.     Headings. The descriptive headings of the several Sections of
this Agreement are inserted for convenience only and do not constitute a part
of this Agreement.

         13.     Governing Law. This Agreement shall be governed by, and
construed in accordance with, the laws of the State of Oklahoma, without regard
to principles of conflicts of law.

         14.     Termination. This Agreement and the respective obligations of
the parties hereunder shall terminate upon written notice by Occidental to H&P
that it shall cease to maintain the effectiveness of the Registration Statement
as permitted by Section l(b) hereof; provided, however, that the respective
obligations of the parties set forth in Section 5 hereof (to the extent that
such obligations arise out of a distribution or distributions of the Shares
pursuant to the Registration Statement) and the obligations of H&P to suspend
use of the Prospectus and any distribution of Shares pursuant to the
Registration Statement shall survive any such termination.

         15.     Counterparts. This Agreement may be executed in one or more
counterparts, each of which when so executed shall be deemed an original, but
all of which together shall constitute one and the same instrument.

         16.     Construction. The parties have participated jointly in the
negotiation and drafting of this Agreement.  In the event any ambiguity or
question of intent or interpretation arises, this Agreement shall be construed
as if drafted jointly by the parties, and no presumption or burden of proof
shall arise favoring or disfavoring either party by virtue of the authorship of
any of the provisions of this Agreement. Any reference in this Agreement to any
law shall be deemed also to refer to all rules and regulations promulgated
thereunder, unless the context requires otherwise. The word "including" shall
mean "including without limitation".


                                      -9- 
<PAGE>   84
         IN WITNESS WHEREOF, the parties hereto have executed this Agreement as 
of the date first above written.

                                        OCCIDENTAL PETROLEUM CORPORATION


                                        By:
                                           -------------------------------------
                                              Name:
                                                   -----------------------------
                                              Title:
                                                    ----------------------------

                                        HELMERICH & PAYNE, INC.

                                        By:
                                           -------------------------------------
                                              Name:
                                                   -----------------------------
                                              Title:
                                                    ----------------------------


                                      -10-
<PAGE>   85
                                                               Exhibit 2.4(b)(x)


                     [Form of Opinion of Steven R. Mackey]

                                 ________, 1996



Occidental Petroleum Corporation
10889 Wilshire Boulevard
Los Angeles, California 90024



Ladies & Gentlemen:

         I am General Counsel of Helmerich & Payne, Inc., a Delaware
corporation ("H&P"), and have acted as counsel to H&P and to Natural Gas
Odorizing, Inc., an Oklahoma corporation ("NGO") and a wholly-owned subsidiary
of H&P, in connection with the Agreement of Plan of Merger, dated as of August
23, 1996 (the "Merger Agreement"), among H&P, NGO, Occidental Petroleum
Corporation, a Delaware corporation ("Occidental"), and OPC Acquisition Corp.,
an Oklahoma corporation (the "Company") and a wholly-owned subsidiary of
Occidental. The Merger Agreement provides for the merger of the Company with
and into NGO, with NGO surviving and becoming a wholly-owned subsidiary of
Occidental, on the terms and conditions set forth in the Merger Agreement.
Pursuant to the Merger Agreement, each share of NGO Common Stock which shall be
issued and outstanding immediately prior to the Effective Time shall, by virtue
of the Merger, be converted into the right to receive a certain number of
shares of the Occidental Common Stock.

         This opinion is being delivered to you pursuant to Section 2.4(b)(x)
of the Merger Agreement. Capitalized terms used in this opinion and not
otherwise defined herein shall have the meanings given them in the Merger
Agreement, provided that "Related Documents" for purposes of this opinion
shall not include the Novation Agreement.

         I am familiar with the corporate proceedings taken by H&P and NGO in
connection with the negotiation and authorization of the Merger Agreement and
the transactions contemplated thereby. In addition, I have made such inquiry of
such of officers and attorneys of H&P and its subsidiaries and have examined
such corporate records, certificates of officers of H&P, of officers of H&P's
subsidiaries and of public officials and such other documents and such
questions of law and facts as I have considered necessary or appropriate to
form the basis of the opinions hereinafter expressed.

         Based upon, and subject to, the foregoing and the other qualifications
hereinafter specified, 






<PAGE>   86
Occidental Petroleum Corporation
________________, 1996
Page 2

I am of the opinion that:


         1.      H&P and NGO are corporations duly incorporated, validly
                 existing and in good standing under the laws of the States of
                 Delaware and Oklahoma, respectively, with full corporate power
                 and authority to own, lease and operate their respective
                 properties and to carry on their respective businesses as they
                 are now being conducted.

         2.      NGO has all requisite corporate power and authority to own,
                 lease and operate the Assets and to carry on the business in
                 which it is engaged and is duly qualified or licensed to do
                 business as a foreign corporation (as listed in Schedule 3.2
                 of the Merger Agreement) and is in good standing under the
                 laws of each state or other jurisdiction in which either the
                 ownership or use of the Assets owned or used by it, or the
                 nature of the activities conducted by it, requires such
                 qualification.

         3.      The authorized capital stock of NGO consists of 20,000 shares
                 of the NGO Common Stock, of which 500 shares are issued and
                 outstanding, and no shares of the NGO Common Stock are held in
                 NGO's treasury.  All of the NGO Shares have been validly
                 issued and are fully paid and nonassessable, and no shares of
                 NGO Common Stock are subject to, nor have any been issued in
                 violation of, any preemptive or similar rights. All of the NGO
                 Shares are held, beneficially and of record, by H&P and are
                 free and clear of any Encumbrances. Except as set forth above
                 in this paragraph 3., there are outstanding (i) no Equity
                 Securities of NGO, and (ii), except for the obligations of H&P
                 and Occidental pursuant to the provisions of the Merger
                 Agreement, no options or other rights to acquire from H&P or
                 NGO, and no obligation of H&P or NGO to issue or sell, any
                 Equity Securities of NGO. There are no (A) outstanding
                 obligations of NGO to repurchase, redeem or otherwise acquire
                 any shares of its capital stock, or (B) Contracts relating to
                 the issuance, sale or transfer of any Equity Securities or
                 other securities of NGO.

         4.      H&P has all requisite corporate power and authority (i) to
                 execute and deliver the Merger Agreement and each of the
                 Related Documents to which it is a party, (ii) to consummate
                 the transactions contemplated thereby, and (iii) to perform
                 the obligations of H&P thereunder, including the execution,
                 delivery and performance of all agreements and documents
                 necessary to effectuate the transactions contemplated thereby.
                 NGO has all requisite corporate power and authority (A) to
                 execute and deliver the Merger Agreement and each of the
                 Related Documents to which it is a party, (B) to consummate
                 the transactions contemplated thereby, and (C) to perform the
                 obligations of NGO thereunder, including the execution,
                 delivery and performance of all agreements and documents
                 necessary to effectuate the transactions





                                      -16-
<PAGE>   87
Occidental Petroleum Corporation
________________, 1996
Page 3

                 contemplated thereby. The execution and delivery by H&P of,
                 and the performance by H&P of its obligations under, the
                 Merger Agreement and each of the Related Documents to which it
                 is a party have been duly authorized by all requisite
                 corporate action on the part of H&P, and no other corporate
                 proceedings on the part of H&P are necessary to authorize the
                 execution, delivery and performance by H&P of the Merger
                 Agreement and each of such Related Documents and the
                 consummation by H&P of the transactions contemplated thereby.
                 The execution and delivery by NGO of, and the performance by
                 NGO of its obligations under, the Merger Agreement and each of
                 the Related Documents to which it is a party have been duly
                 authorized by all requisite corporate action on the part of
                 NGO, and no other corporate proceedings on the part of NGO or
                 its sole shareholder are necessary to authorize the execution,
                 delivery and performance by NGO of the Merger Agreement and
                 each of such Related Documents and the consummation by NGO of
                 the transactions contemplated thereby. The Merger Agreement
                 has been duly executed and delivered by H&P and NGO and
                 constitutes (and each of the Related Documents to which H&P or
                 NGO is a party, and each other agreement, instrument or
                 document executed by H&P or NGO in connection with the
                 transactions contemplated thereby, has been duly executed and
                 delivered by H&P or NGO, as the case may be, and constitutes)
                 a valid and legally binding obligation of H&P or NGO
                 enforceable against H&P or NGO, as the case may be, in
                 accordance with its terms, except that such enforceability may
                 be limited by applicable bankruptcy, insolvency,
                 reorganization, moratorium or similar laws affect creditors'
                 rights generally and equitable principles (whether applied in
                 a court of law or equity).

         5.      [Except as set forth on Schedule 3.6 of the Merger Agreement,]
                 (i) the execution, delivery and performance by H&P and NGO of
                 the Merger Agreement and each of the Related Documents to
                 which H&P or NGO is a party, and (ii) the consummation by H&P
                 and NGO of the transactions contemplated by the Merger
                 Agreement or each of such Related Documents do not and will
                 not (A) contravene, conflict with, or result in a breach or
                 violation of, any of the terms, provisions or conditions of,  
                 (1) the charter or by-laws of H&P or NGO,(2) any resolution
                 known to me adopted by the Board of Directors or the
                 stockholders of H&P or NGO, or (3) any Order or Permit to
                 which H&P or NGO, or any of their respective properties and
                 assets, may be subject, (B) contravene, conflict with, or
                 result in a breach or violation of, any of the terms,
                 provisions or conditions of, or constitute (with or without
                 the giving of notice or the passage of time or both) a default
                 under, or give rise (with or without the giving of notice or
                 the passage of time for both) to any right of termination,
                 amendment, cancellation or acceleration of, or require payment
                 under, any bond, debenture, note, mortgage, indenture, lease
                 or other Contract known to me to which H&P or NGO is a party
                 or by which H&P or NGO or any of their respective properties
                 or assets may be bound or affected, (C) to the best of my
                 knowledge result






<PAGE>   88
Occidental Petroleum Corporation
________________, 1996
Page 4

                 in the imposition or creation of any Encumbrance upon, or with
                 respect to, any of the NGO Shares or the properties or assets
                 owned or used by NGO, or (D), assuming compliance with the
                 matters referred to in Section 3.7 of the Merger Agreement,
                 violate any Federal or Oklahoma law binding upon H&P or NGO.

         6.      To the best of my knowledge, no Consent of, or declaration,
                 filing or registration with, any Person (including any
                 Governmental Body) is required to be obtained or made by H&P
                 or NGO in connection with (i) the execution, delivery or
                 performance by H&P or NGO of the Merger Agreement or any of
                 the Related Documents to which H&P or NGO is a party, or (ii)
                 the consummation by H&P or NGO of the transactions
                 contemplated by the Merger Agreement or any of such Related
                 Documents, other than (A) compliance with any applicable state
                 securities or takeover laws, (B) the filing by NGO of the
                 Certificate of Merger with the Secretary of State of the State
                 of Oklahoma, and (C) other filings with Governmental Bodies in
                 the Ordinary Course of Business of H&P or NGO that are not
                 required to be made prior to the consummation of the
                 transactions contemplated by the Merger Agreement or such
                 Related Documents.

         7.      To the best of my knowledge, except as set forth on Schedule
                 3.18 of the Merger Agreement, there is no Proceeding pending
                 or threatened by, against or involving NGO or any of the
                 Assets.

         8.      To the best of my knowledge, except as set forth on Schedule
                 3.18 of the Merger Agreement, there is no Order to which NGO
                 or any of the Assets is subject.

         9.      To the best of my knowledge, there is no Proceeding pending or
                 threatened by, against or involving H&P, any of its Affiliates
                 or any of the Assets and that challenges, or that may have the
                 effect of preventing, restraining, prohibiting, delaying,
                 making illegal, obtaining damages or other relief in
                 connection with, or otherwise interfering with, the Merger
                 Agreement or any of the transactions contemplated thereby.

         10.     Neither H&P nor NGO is, with respect to the business of NGO,
                 subject to regulation under the PUHCA, the Investment Company
                 Act of 1940, as amended, or the Interstate Commerce Act, nor
                 is either such Person subject to regulation pursuant to any
                 rules or regulations promulgated thereunder. Neither H&P nor
                 NGO is, with respect to such business, a "holding company", or
                 a "subsidiary company" of a "holding company", or an
                 "affiliate" of a "holding company" or of a "subsidiary
                 company" of a "holding company", or a "public utility", within
                 the meaning of the PUHCA and the rules and regulations
                 promulgated thereunder.






<PAGE>   89
Occidental Petroleum Corporation
_____________, 1996
Page 5


         11.     NGO has caused the Merger to become effective this date by
                 executing and filing the Certificate of Merger with the
                 Secretary of State of Oklahoma.


         I am a member of the Oklahoma Bar and for purposes of this opinion do
not hold myself out as an expert on, nor do I express any opinion as to, the
laws of any jurisdiction other than the laws of the State of Oklahoma, the
Federal laws of the United States and the General Corporation Law of the State
of Delaware.

         The opinions expressed in numbered paragraphs 5, 6 and 10 above
regarding compliance with certain laws and regulations are based solely on my
review of those laws and regulations which, in my experience, are normally
applicable to transactions of the type contemplated by the Merger Agreement and
the Related Documents.

         In rendering the opinions set forth in numbered paragraphs 5., 6. and
10. above, I have assumed. that (a) H&P will not in the future take any
discretionary action (including a decision not to act) permitted under the
Merger Agreement or the Related Documents that would result in a violation of
law or order or constitute a breach or default under any other agreement or
instrument to which H&P is a party or by which its properties may be bound or
affected, and (b) H&P will obtain all permits and governmental approvals
required in the future, and take all action similarly required, relevant to
subsequent consummation of the transactions contemplated by the Merger
Agreement and the Related Documents or performance thereof.

         With your approval, I have relied, as to certain matters of fact, on
information obtained from public officials, officers of H&P and its
subsidiaries and other sources believed by me to be responsible, and I have
assumed that the signatures on all documents examined by me are genuine, that
all documents submitted to me as originals are authentic and that all documents
submitted to me as copies conform with the originals, which assumptions I have
not independently verified. Also with your approval, I have relied, as to
certain legal matters, on advice of other lawyers employed by H&P who are more
familiar with such matters.






<PAGE>   90
Occidental Petroleum Corporation
__________________, 1996
Page 6

         This opinion is rendered only to Occidental in connection with the
Merger, and is solely for the benefit of Occidental and its Affiliates in
connection with the Merger Agreement. This opinion may not be relied upon by
Occidental for any other purpose or by any other person, firm or corporation for
any purpose without my prior written consent.

                                        Sincerely,




                                        Steven R. Mackey
                                        Vice President and General Counsel






<PAGE>   91
                                                             Exhibit 2.4(c)(vii)

                     [Form of Opinion of Robert E. Sawyer]

                                _________, 1996

Helmerich & Payne, Inc.
1579 E. 21st Street
Tulsa, Oklahoma 74114

Ladies and Gentlemen:

         I am an Associate General Counsel of Occidental Petroleum Corporation,
a Delaware corporation ("Occidental"), and have acted as counsel to Occidental
and to OPC Acquisition Corp., an Oklahoma corporation (the "Company") and a
wholly-owned subsidiary of Occidental, in connection with the Agreement and
Plan of Merger, dated as of August 23, 1996 (the "Merger Agreement"), among
Occidental, the Company, Helmerich & Payne, Inc., a Delaware corporation
("H&P"), and Natural Gas Odorizing, Inc., an Oklahoma corporation ("NGO"),
providing for the merger of the Company with and into NGO, with NGO surviving
and becoming a wholly-owned subsidiary of Occidental, on the terms and
conditions set forth in the Merger Agreement. Pursuant to the Merger Agreement,
each share of NGO Common Stock which shall be issued and outstanding
immediately prior to the Effective Time shall, by virtue of the Merger, be
converted into the right to receive a certain number of shares of the
Occidental Common Stock.

         This opinion is being delivered to you pursuant to Section 2.4(c)(vii)
of the Merger Agreement. Capitalized terms used in this opinion and not
otherwise defined herein shall have the meanings given them in the Merger
Agreement, provided that "Related Documents" for purposes of this opinion shall
not include the Novation Agreement.

         I am familiar with the corporate proceedings taken by Occidental and
the Company in connection with the negotiation and authorization of the Merger
Agreement and the transactions contemplated thereby. In addition, I have made
such inquiry of such officers and attorneys of Occidental and its subsidiaries
and examined such corporate records, certificates of officers of Occidental,
of officers of Occidental's subsidiaries and of public officials and such other
documents and such questions of law and fact as I have considered necessary or
appropriate to form the basis of the opinions hereinafter expressed. At a
meeting of the Board of Directors of Occidental relating to the adoption of the
Rights Agreement, dated as of October 17, 1986 (the "Rights Agreement"),
between Occidental and Chemical Bank, as successor Rights Agent, the Board of
Directors of Occidental was advised on a number of questions of Delaware law,
including that there is no direct judicial precedent in Delaware regarding an
identical form of rights agreement.






<PAGE>   92
         Based upon, and subject to, the foregoing and the other qualifications
hereinafter specified, I am of the opinion that:

         1.      Occidental is a corporation duly incorporated, validly
existing and in good standing under the laws of the State of Delaware.

         2.      Occidental has all requisite corporate power and authority (i)
to execute and deliver the Merger Agreement and each of the Related Documents
to which it is a party, (ii) to consummate the transactions contemplated
thereby, and (iii) to perform its obligations thereunder, including the
execution, delivery and performance of all agreements and documents necessary
to effectuate the transactions contemplated thereby. The execution and delivery
by Occidental of, and the performance by Occidental of its obligations under,
the Merger Agreement and each of the Related Documents to which it is a party
have been duly authorized by the Board of Directors of Occidental (or a pricing
committee thereof), and no other corporate proceedings on the part of
Occidental are necessary to authorize the execution, delivery and performance
by Occidental of the Merger Agreement and each of such Related Documents and
the consummation by Occidental of the transactions contemplated thereby. The
Merger Agreement has been duly executed and delivered by Occidental.

         3.      [Except as set forth on Schedule 4.3 of the Merger Agreement,]
(i) the execution, delivery and performance by (A) Occidental of the Merger
Agreement and each of the Related Documents to which Occidental is a party, and
(B) the Company of the Merger Agreement, and (ii) the consummation by (1)
Occidental of the transactions contemplated by the Merger Agreement or each of
such Related Documents, and (2) the Company of the transactions contemplated by
the Merger Agreement do not and will not (I) contravene, conflict with, or
result in a breach or violation of, any of the terms, provisions or conditions
of, (a) the charter or by-laws of Occidental, (b) any resolution known to me
adopted by the Board of Directors or the stockholders of Occidental or the
Company, or (c) any Order or Permit known to me to which Occidental or the
Company may be subject, (II) contravene, conflict with, or result in a breach
or violation of, any of the terms, provisions or conditions of, or constitute
(with or without the giving of notice or the passage of time or both) a default
under, or give rise (with or without the giving of notice or the passage of
time or both) to any right of termination, amendment, cancellation or
acceleration of, or require payment under, any bond, debenture, note, mortgage,
indenture, lease or other Contract known to me to which Occidental or the
Company is a party or by which Occidental or the Company or any of their
respective properties or assets may be bound or affected (other than agreements
affecting the listing of the Occidental Common Stock on any securities exchange
outside the United States), (III) to the best of my knowledge, result in the
imposition or creation of any Encumbrance upon, or with respect to, any of the
properties or assets owned or used by Occidental or the Company, or (IV)
assuming compliance with the matters referred to in Section 4.4 of the Merger
Agreement, violate any Federal, California or New York Law binding upon
Occidental or the Company.





                                      2
<PAGE>   93
         4.      To the best of my knowledge, no consent of, or declaration,
filing or registration with, any Person (including any Federal, California or
New York Governmental Body) is required to be obtained or made by Occidental or
the Company in connection with (i) the execution, delivery or performance by
(A) Occidental of the Merger Agreement or any of the Related Documents to which
Occidental is a party, or (B) the Company of the Merger Agreement, or (ii) the
consummation by (1) Occidental of the transactions contemplated by the Merger
Agreement or any such Related Documents, or (2) the Company of the transactions
contemplated by the Merger Agreement, other than (I) compliance with the
applicable requirements of the HSR Act, (II) compliance with any applicable
state securities or takeover laws, (III) filings with federal and state
securities commissions in connection with the transactions contemplated by the
Registration Agreement, and (IV) other filings with Governmental Bodies in the
Ordinary Course of Business of Occidental or the Company that are not required
to be made prior to the consummation of the transactions contemplated by the
Merger Agreement or such Related Documents.

         5.      The shares of the Occidental Common Stock issuable pursuant to
the provisions of the Merger Agreement (not including the rights (the "Rights")
issued in respect of the Occidental Common Stock pursuant to the Rights
Agreement) have been duly authorized for such issuance and, when issued as
contemplated by such provisions and when certificates therefor have been duly
countersigned, will be validly issued, fully paid and non-assessable. Such
issuance of such shares is not the subject of any preemptive rights.

         6.      The Rights included with the Occidental Common Stock to be
issued pursuant to the provisions of the Merger Agreement have been duly
authorized for issuance and, when the Occidental Common Stock with which they
are associated is issued as contemplated by such provisions and when
certificates therefor have been duly countersigned, such Rights will be
validly issued.

         7.      To the best of my knowledge, there is no Proceeding pending,
or threatened by, against or involving Occidental or any of its Affiliates and
that challenges, or that may have the effect of preventing, restraining,
prohibiting, delaying, making illegal, obtaining damages or other relief in
connection with, or otherwise interfering with, the Merger Agreement or any of
the transactions contemplated thereby.

         In rendering the opinions set forth in numbered paragraphs 3 and 4
above, I express no opinion as to NGO. In rendering the opinion set forth in
numbered paragraph 3 above, I have assumed that NGO has not breached or
violated, and as a result of the Merger will not breach or violate, any of the
terms, provisions or conditions of, any bond, debenture, note, mortgage,
indenture, lease or other Contract creating or evidencing an obligation in
respect of money borrowed under circumstances such that, as of the Effective
Time, any other person has a right of acceleration or other remedy against NGO





                                      3
<PAGE>   94
under the terms of any such bond, debenture, note, mortgage, indenture, lease
or other Contract.

         I am a member of the California and New York Bars and for purposes of
this opinion do not hold myself out as an expert on, nor do I express any
opinion as to, the laws of any jurisdiction other than the laws of the State of
California, the laws of the State of New York, the Federal laws of the United
States and the General Corporation Law of the State of Delaware.

         The opinion expressed in numbered paragraphs 3 and 4 above regarding
compliance with certain laws and regulations is based solely on my review of
those laws and regulations which, in my experience, are normally applicable to
transactions of the type contemplated by the Merger Agreement and the Related
Documents, and I express no opinion as to the securities or Blue Sky laws of
the various jurisdictions in which the Occidental Common Stock is offered
(other than United States Federal securities laws).

         In rendering the opinions set forth in numbered paragraphs 3 and 4
above, I have assumed, that (a) Occidental will not in the future take any
discretionary action (including a decision not to act) permitted under the
Merger Agreement or the Related Documents that would result in a violation of
law or order or constitute a breach or default under any other agreement or
instrument to which Occidental is a party or by which its properties may be
bound or affected, and (b) Occidental will obtain all permits and governmental
approvals required in the future, and take all action similarly required,
relevant to subsequent consummation of the transactions contemplated by the
Merger Agreement and the Related Documents or performance thereof.

         With your approval, I have relied, as to certain matters of fact, on
information obtained from public officials, officers of Occidental and its
subsidiaries and other sources believed by me to be responsible, and I have
assumed that the signatures on all documents examined by me are genuine, that
all documents submitted to me as originals are authentic and that all documents
submitted to me as copies conform with the originals which assumptions I have
not independently verified. Also with your approval, I have relied, as to
certain legal matters, on advice of other lawyers employed by Occidental who are
more familiar with such matters.

         This opinion is rendered only to H&P and to Gable Gotwals Mock
Schwabe, special counsel for Occidental in connection with the Merger, and is
solely for the benefit of H&P in connection with the Merger Agreement and the
benefit of Gable Gotwals Mock Schwabe in connection with its opinion pursuant
to the Merger Agreement. This opinion may not be relied upon by H&P or Gable
Gotwals Mock Schwabe for any other purpose or by any other person, firm or
corporation for any purpose without my prior written consent.

                                        Very truly yours,





                                      4
<PAGE>   95
                                                            Exhibit 2.4(c)(viii)





                [FORM OF OPINION OF GABLE GOTWALS MOCK SCHWABE]





                                __________, 1996



Helmerich & Payne, Inc.
1549 East 21st Street
Tulsa, Oklahoma 74119

Ladies & Gentlemen:

         We are serving as special counsel to Occidental Petroleum Corporation,
a Delaware corporation ("Occidental"), and to OPC Acquisition Corp., an
Oklahoma corporation (the "Company") and a wholly-owned subsidiary of
Occidental, in connection with the Agreement of Plan of Merger dated as of
August 23, 1996 (the "Merger Agreement"), among Occidental, the Company,
Helmerich & Payne, Inc., a Delaware corporation ("H&P"), and Natural Gas
Odorizing, Inc., an Oklahoma corporation ("NGO") and a wholly-owned subsidiary
of H&P. The Merger Agreement provides for the merger of the Company with and
into NGO, with NGO surviving and becoming a wholly owned subsidiary of
Occidental, on the terms and conditions set forth in the Merger Agreement.
Pursuant to the Merger Agreement, each share of NGO Common Stock which shall be
issued and outstanding immediately prior to the Effective Date shall, by virtue
of the Merger, be converted into the right to receive a certain number of shares
of the Occidental Common Stock.

         This opinion is being delivered to you pursuant to Section
2.4(c)(viii) of the Merger Agreement. Capitalized terms used in this opinion
and not otherwise defined herein shall have the meanings given them in the
Merger Agreement, provided that "Related Documents" for purposes of this
opinion shall not include the Novation Agreement.

         We are familiar with the corporate proceedings taken by Occidental and
the Company in connection with the negotiation and authorization of the Merger
Agreement and the transactions contemplated thereby. In addition, we have
reviewed the Merger Agreement, the Related Documents and have examined such
corporate records considered necessary or appropriate to form






<PAGE>   96
Helmerich & Payne, Inc.
__________, 1996
Page 2

the basis of the opinions hereinafter expressed.



         Based upon, and subject to, the foregoing and the other qualifications
hereinafter specified, we are of the opinion that:


         1.       The Company is a corporation duly incorporated, validly 
                  existing and in good standing under the laws of the State of
                  Oklahoma.             


         2.       The Company has all requisite corporate power and authority 
                  (i) to execute and deliver the Merger Agreement, (ii) to
                  consummate the transactions contemplated thereby, and (iii) to
                  perform its obligations thereunder. The execution and delivery
                  by the Company of, and the performance by the Company of its
                  obligations under, the Merger Agreement have been duly
                  authorized by the Board of Directors of the Company, and no
                  other corporate proceedings on the part of the  Company are
                  necessary to authorize the execution, delivery and performance
                  by the Company of the Merger Agreement and the consummation by
                  the Company of the transactions contemplated thereby. 


         3.       The Merger Agreement has been duly executed and delivered by 
                  Occidental and the Company and constitutes (and in the case 
                  of Occidental, each of the Related Documents to which
                  Occidental is a party has been duly executed and delivered by
                  Occidental and constitutes) a valid and legally binding
                  obligation of Occidental or the Company enforceable against
                  Occidental or the Company, as the case may be, in accordance
                  with their respective terms, except that such enforceability
                  may be limited by applicable bankruptcy, insolvency,
                  reorganization, moratorium or similar laws affecting
                  creditors' rights generally and equitable principles (whether
                  applied in a court of law  or equity). To the extent that this
                  opinion extends to the enforceability of the Merger Agreement
                  and Related Documents against Occidental, we are relying on
                  the opinion of Mr. Robert E. Sawyer, Associate General Counsel
                  of Occidental, a copy of which is appended hereto, as to the
                  due authorization, execution and delivery of the Merger
                  Agreement and such Related Documents by Occidental.          


         4.       [Except as set forth in Schedule 4.3 of the Merger 
                  Agreement,] the execution, delivery and performance by the
                  Company of the Merger Agreement and the consummation by the
                  Company of the transactions contemplated by the Merger
                  Agreement do not and will not (i) contravene, conflict with or
                  result in a breach or violation of, any of the terms,
                  provisions or conditions of, (a) the Certificate  of     
                  Incorporation or bylaws of the Company, (b) any resolution
                  adopted by the Board of                                     

                  





<PAGE>   97
Helmerich & Payne. Inc.
__________, 1996
Page 3

                  Directors or the sole stockholder of the Company, or (c) any
                  Order or Permit known to us to which the Company may be
                  subject, or (ii) assuming compliance with the matters referred
                  to in Section 4.4 of the Merger Agreement, violate any Federal
                  or Oklahoma law binding upon the Company.

         5.       To the best of our knowledge, no consent of, or declaration,
                  filing or registration with, any Oklahoma Governmental Body is
                  required to be obtained or made by Occidental or the Company
                  in connection with (i) the execution, delivery or performance
                  by (A) Occidental of the Merger Agreement or any of the
                  Related Documents to which Occidental is a party, or (B) the
                  Company of the Merger Agreement, or (ii) the consummation by
                  (l) Occidental of the transactions contemplated by the Merger
                  Agreement or any such Related Documents, or (2) the Company of
                  the transactions contemplated by the Merger Agreement, other
                  than any filings with Oklahoma Governmental Bodies in the
                  Ordinary Course of Business of the Company that are not
                  required to be made prior to consummation of the transactions
                  contemplated by the Merger Agreement or such Related
                  Documents.


         We are members of the Oklahoma Bar and for purposes of this opinion do
not hold ourselves out as experts on, nor do we express any opinion as to, the
laws of any jurisdiction other than the laws of the State of Oklahoma and the
Federal laws of the United States.

         The opinions expressed in numbered paragraphs 4. and 5. above regarding
compliance with certain laws and regulations are based solely on our review of
those laws and regulations which, in our experience. are normally applicable to
transactions of this type contemplated by the Merger Agreement and the Related
Documents, and we express no opinion as to the securities or Blue Sky laws of
the various jurisdictions in which the Occidental Common Stock is offered
(other than United States Federal securities laws).

         With your approval, we have relied, as to certain matters of fact, on
information obtained from public officials, officers of Occidental and its
subsidiaries and other sources believed by us to be responsible, and we have
assumed that the signatures on all documents examined by us are genuine, that
all documents submitted to us as original are authentic and that all documents
submitted to us as copies conform with the originals, which assumptions we have
not independently verified.






<PAGE>   98
Helmerich & Payne, Inc.
__________, 1996
Page 4


         This opinion is rendered only to H&P and is solely for the benefit of
H&P in connection with the Merger Agreement. This opinion may not be relied
upon by H&P for any other purpose or by any other person, firm or corporation
for any purpose without our prior written consent.

                                        Sincerely,




                                        GABLE GOTWALS MOCK SCHWABE








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