EXHIBIT 10(b)(xiii)

                               SECOND AMENDMENT TO
                               RESTATEMENT OF THE
                             1987 STOCK OPTION PLAN


         WHEREAS, ANADARKO PETROLEUM CORPORATION (the "Company") has heretofore
adopted and amended the 1987 STOCK OPTION PLAN ("Plan"); and

         WHEREAS, the Company desires to further amend the Plan:

         NOW, THEREFORE, the Plan shall be amended, effective as of March 30,
2000, as follows:

1.       The following paragraph shall be added to the end of Paragraph 8(c):

         Notwithstanding any other provision of this Plan to the contrary, for
purposes of this Plan, a Change of Control shall not include any votes,
transactions, acquisitions of stock ownership, changes in board composition, or
other actions, transactions or consequences of any nature whatsoever, whether
viewed in isolation or in the aggregate, occurring in connection with or
resulting from the transactions contemplated by the Agreement and Plan of Merger
among Anadarko Petroleum Corporation, Dakota Merger Corp., and Union Pacific
Resources Group Inc., dated as of April 2, 2000 (as it may be amended or
supplemented from time to time) and any related documents.

2.       As amended hereby, the Plan is specifically ratified and reaffirmed.

         IN WITNESS WHEREOF, the parties hereto have caused these presents to be
executed this 30th day of March, 2000.

                                    ANADARKO PETROLEUM CORPORATION


                                    By:
                                        ----------------------------------------
                                        Charles G. Manley
                                        Sr. Vice President, Administration