Abstract:

Tarim, Junggar and Turpan-Hami Basins in Xinjiang are multicyclic ones characterized by the superimposition of multiphase and multi-prototype basins. During their evolution process, several times of extensions and compressions took place alternately, thus leading to the formation of the basic tectonic framework of uplifts alternated with depressions, or convexes with sags. Some successive depressions or sags were therefore received several suites of source beds. The hydrocarbon generating periods of different source beds had met and even coincided with each other in certain periods of time. This resulted in four peak periods of hydrocarbon generation, i. e. the end of Early Paleozoic to Devonian,Permian to Triassic, the end of Jurassic to Cretaceous as well as the end of Tertiary to Quaternary. Several regional tectonic movements happened coincidding with or a bit later than the four peak periods, so that hydrocarbon expulsion and trap formation took place contemporaneously in the basins, and this thus decided the peak periods of oil/gas fomation. Hydrocarbon distribution of the basins is mainly controlled by the large uplift zone,fault-anticline belt and slope-faulted terrance led to the formation of three major composite hydrocarbon accumulation belts such as the uplift-drape anticline type, foreland overthrust belt type and slope-faulted terrance type. These are the primary targets for hydrocarbon exploration in future.