• XTO Energy Inc., Fort Worth, plans to boost its oil holdings by purchasing producing properties in the Permian Basin of West Texas and the Powder River Basin of Wyoming from ExxonMobil Corp. for $336- to $341 million. The final price is subject to revenue adjustments and depends on property performance during the next 12 months. XTO estimates proved reserves to be about 38 million BOE, 82% proved developed. Upside reserve potential of 30- to 50 billion cu. ft. of gas exists through future development of Powder River coalbed methane (CBM). ExxonMobil will retain an overriding royalty interest in the CBM reserves. The acquisitions will initially add production of about 6,600 BOE per day. XTO will operate more than 80% of the value of these properties. • Encore Acquisition Co., Fort Worth, (NYSE: EAC) plans to buy operated gas properties in Overton Field, Smith County, Texas, for $82 million from an unidentified group of private sellers. Current production from the Overton Field assets is primarily from multiple tight sandstone reservoirs in the Travis Peak and Cotton Valley formations at depths ranging between 8,000 and 11,500 feet, and totals some 7 million cu. ft. of gas equivalent per day (94% gas). The assets include 46 billion cu. ft. equivalent of proved reserves and 111 billion of total reserves. • Output Exploration LLC, Stafford, Texas, has acquired White Oak Energy LLC, a Gulf Coast-focused owner of more than 30 billion cu. ft. equivalent of proved reserves located primarily onshore the Texas Gulf Coast, for $67.5 million. Output simultaneously sold $15.15 million of White Oak's Louisiana properties. The buyer was not disclosed. White Oak's properties will more than double Output's reserve base to 68 billion equivalent of proved reserves (74% gas). • Range Resources Corp., Fort Worth, (NYSE: RRC) has acquired a privately held Permian Basin producer for $22.5 million. Reserves are approximately 22 billion cu. ft. of gas equivalent (52% proved developed). Net production is 3.3 million cu. ft. equivalent per day (more than 85% operated; 75% oil). The reserve-to-production ratio is more than 15 years. Range financed the acquisition with credit-facility borrowings. • Arena Resources Inc., Tulsa, (Amex: ARD) plans to acquire an 82% working interest (67.5% net revenue interest) in a mineral lease in the East Hobbs San Andres unit, Lea County, N.M., for $10.1 million. The unit consists of approximately 920 acres with existing oil and gas production from 19 wells. The interest carries proved reserves of more than 6.4 million BOE and net daily production of approximately 225 BOE. With the purchase, Arena will have net daily production of approximately 700 BOE and proved reserves of more than 15.9 million BOE. • Privately held Crow Creek Energy LLC, Tulsa, Okla., has acquired the U.S. oil and gas business of Wilshire Enterprises Inc., Jersey City, N.J., (Amex: WOC) for $13.3 million. Crow Creek is a Natural Gas Partners portfolio company.