1 EXHIBIT 15 AWARENESS LETTER OF INDEPENDENT PUBLIC ACCOUNTANTS November 12, 1999 Union Pacific Resources Group Inc. 777 Main Street Fort Worth, Texas 76102 We are aware that Union Pacific Resources Group Inc. has incorporated by reference in its Registration Statements No. 333-62181 on Form S-3 and No. 333-22613 and No. 333-35641 on Form S-8 its Form 10-Q for the quarter ended September 30, 1999, which includes our report dated October 25, 1999 covering the unaudited interim financial information contained therein. Pursuant to Regulation C of the Securities Act of 1933, that report is not considered a part of the registration statement prepared or certified by our firm or a report prepared or certified by our firm within the meaning of Sections 7 and 11 of the Act. Very truly yours, ARTHUR ANDERSEN LLP Fort Worth, Texas