<PAGE>
 
    This Release shall be governed by and construed in accordance with the laws 
of the State of Texas.

    IN WITNESS WHEREOF, Jackson and the Trust, for and on behalf of 
Jackson/Trust and their Affiliates, and Zapata and Cimarron, for and on behalf
of Zapata/Cimarron and their Affiliates, each has caused this Release to be
executed as of the date first written above.

   
                               /s/ ROBERT W. JACKSON
                               -----------------------------------
                               ROBERT W. JACKSON

                         
                               ROBERT W. JACKSON TRUST                 
                                                                             
                                                                             
                               By:  /S/ ROBERT W. JACKSON            
                                  ---------------------------------  
                                  ROBERT W. JACKSON, TRUSTEE



                               ZAPATA CORPORATION
                                                                            
                                                                            
                               By:  /S/ JOSEPH L. von ROSENBERG, III            
                                  ---------------------------------             
                                  JOSEPH L. von ROSENBERG, III                  
                                  Vice President, General Counsel and Secretary 


                               CIMARRON GAS HOLDING COMPANY          
                                                                            
                                                                            
                               By:  /S/ JOSEPH L. von ROSENBERG, III           
                                  ---------------------------------            
                                  JOSEPH L. von ROSENBERG, III                 
                                  Vice President, General Counsel and Secretary 

                                      -6-