Paleostructural Evolution and Relationship with Hydrocarbon of Permian in Yining Sag

The tectonic deformation in Yining sag is so strong that leads to unclear understandings of the tectonic evolution up to now. This paper restored the paleotectonic features of Permian-Paleogene in Yining sag by means of the seismic and drilling data,including the denudation thickness,by which predicted the probable hydrocarbon migration and accumulation for the Permian source rocks. The result shows that Yining sag was converted from fault depression into sag in Triassic; the sag's shape appears low in north and west and high in south and east in general from Permian to Paleogene; in the Permian,the northern part of the sag was a deep rifted belt,the south and east parts were in slope area that looks like steeper in the south than in the east; in the Triassic,the sag structure became lower,the sub-swell zone in the central sag occurred some small swells extending along NWW; in the Jurassic,the subduction center of the sag transferred toward NW,appearing flat in the south slope and steep in the east one. It is concluded that the fault swell near Well Ning-4 and fault nose at the west of Well Yi-2 in center of the sag and fault nose in the south of Yingtamu could be the favorable hydrocarbon accumulation areas of Tiemulike formation in Yining sag.