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                                                                   EXHIBIT 10(i)
 
                                                               SHELL OIL COMPANY
 
                                                         ONE SHELL PLAZA
                                                         P. O. BOX 2463
                                                         HOUSTON, TEXAS
77252-2463
 

                                                                  
C. J. SHEARER                    J. E. KREBS                            P. L. CUNEO
VICE PRESIDENT                   PRESIDENT                              DIRECTOR OF TECHNOLOGY
SHELL CHEMICAL COMPANY           SHELL E&P TECHNOLOGY COMPANY,          EQUILON ENTERPRISES LLC
WESTHOLLOW TECHNOLOGY CENTER     A DIVISION OF SHELL                    WESTHOLLOW TECHNOLOGY CENTER
                                 EXPLORATION & PRODUCTION COMPANY
                                 BELLAIRE TECHNOLOGY CENTER

 
January 11, 1999
                                                              Our Ref: STVP LGVP
Shell Internationale Research Maatschappij, B. V.
P. O. Box 162
30 Carel van Bylandtlaan
The Hague 2501, The Netherlands
 
Gentlemen:
 
SUBJECT: AGREEMENT FOR RESEARCH SERVICES
 
This refers to the Agreement dated January 1, 1960, between Shell Oil Company
and Shell Internationale Research Maatschappij, B.V. entitled "Agreement for
Research Services," as amended.
 
Programs and budget for the year 1999 having been exchanged in accordance with
paragraph 9 of said Agreement, and the parties having agreed to the factors
referred to in subparagraph 10 (c) we now wish to confirm the understanding with
you that said Agreement, as amended, shall be continued for the calendar year
1999, with the amount of the monthly payment to be determined and paid according
to the terms of said Agreement.
 
Please indicate your concurrence to the continuation of the said Agreement on
the basis indicated above by executing both of the executed letters enclosed and
returning one of them to us and retaining the other for your files.
 
                               Yours very truly,
                    For and on behalf of Shell Oil Company:
 

                                                                        
Shell Chemical Company                 Shell E&P Technology Company a         Shell Oil Products Company
                                         division of Shell Exploration &
                                         Production
 
    /s/ C. J. SHEARER                      /s/ J. E. KREBS                        /s/ P. L. CUNEO
By: -------------------------------    By: --------------------------------   By: ------------------------
          C. J. Shearer                          J. E. Krebs                            P. L. Cuneo

 
Accepted and Agreed to:
 
Shell Internationale Research Maatschappij, B. V.
 

                                                                        
 
     /s/ B. STOUTHAMER                      /s/ T. N. WARREN                   /s/ G. J. VAN LUIJK
By: -------------------------------    By: --------------------------------   By: ------------------------
          B. Stouthamer                          T. N. Warren                           G. J. Van Luijk

 
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