Petrogeologic feature of Wushi Sag in Talimu Basin

The study on the petrogeologic feature of Wushi Sag is of importance to accurately understanding the objective formation in this area. Wushi Sag is a secondary negative structural unit of Kuche Depression. It is a Mesozoic—Cenozoic sedimentary sag which develops on Palaeozoic base. Precambrian system floor is buried relatively deep, and Mesozoic develops well in the sag. The deposit is mainly composed of fluvial and lacustrine facies. Several sets of Mesozoic and Palaeozoic hydrocarbon sourse rock appear around the sag. A series of thrusts develop in the sag, and their strikes are near E—W. The thick mudstone of Paleogene is a set of good cap formation. A commercial gas flow is found in Cretaceous Shushan river under the thick mudstone. It shows that the sag has its own hydrocarbon supply and accumulation system. It is pointed that, the main objective formation of exploration in Wushi Sag are Cretaceous sandstone and Paleogene sandstone, at the same time, Jurassic sandstone must be given consideration.