Formation,Evolution and Hydrocarbon-Controlling Geological Conditions of Major Paleohighs,Tarim Basin

The distribution, formation and evolution of paleohighs play a decisive role for hydrocarbon accumulation. Based on the seismic, log and test data, this paper systemically studies the distribution and evolution of different geological paleohighs in Tarim Basin. Through the comprehensive comparison of the properties and evolutional characteristics and hydrocarbon geological conditions of three paleohighs (Tazhong, Tabei and Bachu), it analyzes the favorable exploration domains during different periods, and indicates that the paleohigh in the crucial hydrocarbon-accumulation period and its later evolution impact on the basin's geological structure and restrict the hydrocarbon accumulation and distribution. These lead to different main controlling factors of hydrocarbons and different hydrocarbon accumulation zones in different periods. Tabei and Tazhong are the favorable accumulation areas in the late Caledonian period. These highs and their slopes of Tabei, Bachu, Tazhong, Tadong are the favorable accumulation areas in the late Hercynian period. In the Himalayan period, Bachu high and its ramp are the main favorable areas for exploration, and Tadong also deserves attention.