Abstract: As the major reservoir in Shengquan oilfield, the Sanjianfang formation has characteristics which are very important to its rolling exploration and development. The study shows that: ① the Sanjianfang formation reservoir in Middle Jurassic is a set of coarse grain detrital sediment, belongs to river-shallows lake beach depositional system with braided river delta facies;② it can be further divided into the distributary channel, channel bar, levee (beach), crevasse-splay, subaqueous distributary channel, sheet bar, plain, and frontal sediment of braided stream sedimentary subfacies. ③ different sedimentary microfacies showed obvious different reservoir lithophysical properties and oil-bearing capabilities. Reservoirs of braided channel, channel bar, subaqueous braided channel microfacies have quite good lithophysical properties, they are favorable facies belt for oil-gas accumulation, while those of the overbar, levee(beach) and sheet sand are relatively poor.

Key words: Turpan basin, Hami basin, Shengquan oilfield, Middle Jurassic, sedimental lithofacies, oil and gas accumulation