• Sibneft and Yukos have merged and created YukosSibneft Oil Co., Russia's largest oil and gas producer. The company may change its name. • Central Resources Inc. and affiliate Central International Corp. have acquired a 100% working interest in the Catriel Oeste Field in Rio Negro province, Argentina, from Petrobras Energia SA and another Argentine operator. The field produces approximately 1,500 bbl. of oil per day. Central estimates the proved reserves at 15 million BOE. • EnerGulf Resources Inc., Vancouver, has acquired a 25% working interest in the Alborada contract between Gulfsands Petroleum Ltd., Houston, and Empresa Colombiana de Petroleos, covering 30,622 hectares in the upper Magdalena Basin in Colombia, for US$368,983. • CanArgo Energy Corp. plans to sell its 45% interest in Fountain Oil Boryslaw, a subsidiary of Boryslaw Oil Co., to a Ukrainian company for US$1 million.