EXHIBIT 10.2 January 29, 2003 Flying J Oil & Gas Inc. Big West Oil & Gas Inc. 333 West Center Street 333 West Center Street North Salt Lake, Utah 84504-2805 North Salt Lake, Utah 84504-2805 Attn: Mr. Chris J. Malan General Counsel and Manager of Lands Re: Addendum to Purchase and Sale Agreement dated December 13, 2002 Gentlemen: Pursuant to that certain Purchase and Sale Agreement dated December 13, 2002, by and between Flying J Oil & Gas Inc. and Big West Oil & Gas Inc. as Seller and NPC Inc. as Buyer (the "PSA"), the Purchase Price as adjusted is to be paid in the form of common stock of St. Mary Land & Exploration Company ("St. Mary") such stock being referred to as the "St. Mary Common Stock". The parties to the PSA have agreed to the value of the Title Defects yielding a reduction to the Purchase Price in the amount of $479,548. In accordance with the terms of Sections 2.01 and 7.03(c) of the PSA the effect of this adjustment to the Purchase Price results in a decrease in the number of shares of St. Mary Common Stock to be issued to Seller from 3,400,000 shares to 3,380,818 shares. It is the understanding of the undersigned that the Seller desires that these shares of St. Mary Common Stock shall issue as follows: Flying J Oil & Gas Inc. 1,690,409 Big West Oil & Gas Inc. 1,690,409 to be owned in accordance with the terms of the PSA and the additional agreements attached to the PSA. Big West Oil & Gas Inc. has indicated that it desires the right to assign all or a portion of its shares of St. Mary Common Stock to Flying J Oil & Gas Inc. after Closing, subject to the provisions of the PSA and the Exhibits thereto. St. Mary hereby consents and agrees to this assignment of shares and has no objection whatsoever to all, or any portion thereof, of the shares of St. Mary Common Stock being owned by Flying J Oil & Gas Inc. St. Mary, Flying J Oil & Gas Inc., and Big West Oil & Gas Inc. each agrees that it shall execute, acknowledge and deliver or cause to be executed, acknowledged and delivered, such instruments and instructions and such other action as may be necessary or advisable to enable this transfer and assignment of shares of St. Mary Common Stock as between Big West Oil & Gas Inc. and Flying J. Oil & Gas Inc. to occur subject to the provisions of the PSA and the Exhibits thereto. The parties have further agreed that the certificate evidencing these shares of St. Mary Common Stock shall be delivered directly to St. Mary Land & Exploration Company by the transfer agent. To accommodate an unanticipated issue affecting Buyer, Seller has agreed to convey all of its interests in that portion of the Interests located in the State of Utah to Nance Petroleum Corporation, the parent of the Buyer. Unless otherwise defined in this letter, capitalized terms used herein shall have the meaning given to such terms in the PSA. If this letter properly sets forth our agreement regarding the matters addressed herein, please so signify by signing below. Very truly yours, St. Mary Land & Exploration NPC Inc. Company By: /s/ MILAM RANDOLPH PHARO By: /s/ RONALD B. SANTI -------------------------------- ------------------------ Milam Randolph Pharo Ronald B. Santi Vice President - Land & Legal Vice President - Land Agreed to and accepted this 29th day of January, 2003: Flying J Oil & Gas Inc. Big West Oil & Gas Inc. By: /s/ CHRIS J. MALAN By: /s/ CHRIS J. MALAN -------------------------------- ------------------------- Chris J. Malan Chris J. Malan General Counsel and Manager of Lands General Counsel and Manager of Lands