Formation Conditions of Oil and Gas Fields in Continental Sedimentary Basins in China

Zaiyi Tian, Du Yonglin

Preliminary studies of oil fields such as Daqing, Shengli, Liaohe, Kelamayi, and Changqing indicate the following conditions of oil field formation in continental sedimentary basins. (1) Sedimentary basins are the basic structural units for the formation of oil and gas fields, but basin characteristics differ. (2) The deepest area of lacustrine deposition is the petroleum generation zone, where oil migrates a short distance. Therefore, oil field distribution is controlled by the petroleum generation sag. (3) Oil and gas accumulation is controlled by sedimentary facies, and the favorable facies zones are distributive areas of prolific oil fields. (4) The sedimentary basin has geologic evolution stages characterized by fault, fault-depression, and depression-depauperization These stages relate well to hydrocarbon generation, migration, and accumulation as well as to tectonic movement. (5) The depositional sequence presents favorable injection-type migration and accumulation. (6) Oil trap formation is controlled by the development of structures in a basin. Different types of oil and gas traps occur in different tectonic units.

AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.