Japan and Conoco launched a U.S. drilling venture.

Conoco and the Japanese, including Nippon Mining and the state-owned Japan National Oil Corp., announced a $135-million joint venture calling for about 20 exploratory oil and gas wells in five states and the Gulf of Mexico. Conoco, a subsidiary of Du Pont, will be the operator for the program. Nippon Mining is a major petroleum refiner and a petrochemical and nonferrous-metal producer.