Geological evolution and petroleum features of the Kashi sag in the western Tarim basin, NW China

Kashi sag has the different geological evolution and petroleum features from the other parts of the Tarim basin. The basement of the Kashi sag is characterized by the faulted-block structure. The Paleozoic depocenter is located at the eastern part of the Kashi sag, while the Mesozoic depocenter is at the western part, and the Cenozoic depocenter is at eastern part of the Kashi sag again. Interaction of the foreland fold-thrust belt of the Southern Tianshan orogen and the foreland fold-thrust belt, of the West Kunlun orogen complicates the structural deformation of the western part of the Kashi sag, and short-axial folds with inclined-hinge develop in the western part of the Kashi sag. The structural deformation of the eastern part of the Kashi sag is comparatively uncomplicated, and linear-folds with horizontal-hinge develop. Although favorable petroleum condition exists, the oil-gas accumulation is more complicated in the Kashi sag.