• Forest Oil Corp., Denver, and partner, The Anschutz Overseas Corp., via their South African subsidiaries have agreed with Mvelaphanda Holdings with respect to blocks 1 and 2 offshore. The agreement gives Mvelaphanda the right to acquire an initial 10% interest in both concessions, which cover approximately 13 million acres, and is intended to comply with the government directive for native African participation in the upstream sector. The group plans to commence drilling in October, with the first of a four-well program designed to determine gas reserves for the area. Forest and Anschutz have a 70% and 30% working interest respectively. • Chevron Corp., San Francisco, has purchased an additional 5% stake in the Tengizchevroil joint venture in western Kazakhstan from the Republic of Kazakhstan. The deal increases Chevron's equity interest in TCO to 50%. • Vintage Petroleum Inc., Tulsa, has purchased 100% of the interest formerly held by Perez Companc in two concessions in the Cuyo Basin covering approximately 104,000 acres in the Mendoza province of Argentina for $39.6 million. -Heather H. Read