Geodynamic Evolution and Its Significance upon Hydrocarbon Systems in Tarim Basin, China

He, Dengfa¹, Chengzao Jia², Xinyuan Zhou³, Chaojun Zhang¹, Xuejun Pi³ (1) Research Institute of Petroleum Explorarion and Development, Beijing, China (2) PetroChina Ltd, China (3) Tarim Oilfield Company, PetroChina Limited Company

The Tarim Basin is a large composite and superimposed sedimentary basin developed upon pre-Sinian continental basement. It has undergone three mega-cycles of extension and compression. During Sinian to Middle Devonian, which is called a period of paleo-Asian or proto-Tethyan, it had developed as a continental rift and then to passive margin and to fore­land basin at the end. During Late Devonian to Triassic, a period of paleo-Tethyan, it had been a continental rift and then passive margin at the beginning, and evolved into a retro­arc extensional basin and finally become a retro-arc foreland basin in its southwestern mar­gin. During Jurassic to Quaternary, a period of neo-Tethyan, it had started as a continental rift or depression, followed by intervening local or regional compression, and at last evolved into a large composite foreland basin. The long and multiple periods of tectonic evolution has resulted in the complex superimposition of proto-basins of variable types in different periods, giving rise to a complicated geological framework.

The extensional sequences is much more continuous, containing the three series of effective source rocks such as Cambrian to Ordovician, Carboniferous to Permian, and Lower to Middle Jurassic. The compression basins are characterized by rapid changes in the depositional systems. Such compressions has formed lots of structures ready for hydrocar­bon trapping, and accordingly given rise to three critical moments for oil and gas accumu­lation. The exploration up to now has proved that the Tarim basin has been rich in oil and gas, and has great potential for exploration.