Petroleum geology of the Tarim Basin, NW China: Recent advances

The Tarim Basin is located in the Xijiang Uygur Autonomous Region of NW China, and covers an area of about 560,000 sq. km. At dawn on September 22nd, 1984, Well Shashen-2 (drilled by a team from the Ministry of Geology and Mineral Resources) blew-out spectacularly when it penetrated Ordovician dolomites at a depth of 5,392m. The blow-out marked the discovery of a highly-productive oil- and gasfield, from which daily output has reached 1,000 m(3) oil and 2 MM (million) m(3) gas. Over the last decade or so, 560,000 km of gravimetric surveys (scale 1:10(6)) and 338,000 km of airborne magnetic surveys (1:200,000) have been completed. Some 200,000 line-km of 2-D seismic profiles and 10,000 km of 3-D surveys have also been carried out, and more than 200 wells have been drilled. Twenty-two oilfields producing from ten stratigraphic intervals, four of which have reserves of more than 100 million tons, have been discovered or explored, indicating that the future prospects for petroleum exploration in the basin are very favourable (Kang and Huang, 1992; Jia, 1991a; 1991b). Annual production in the Tarim Basin reached 2,300,000 t in 1995 (Kang et al., 1996).