民和盆地巴州坳陷中侏罗─下白垩统沉积相序列及其含油气意义

民和盆地巴州坳陷的侏罗－下白垩统主要发育曲流河、辫状河、滨浅湖、水下扇和三角洲沉积。窑街组的漫滩沼泽和湖湾沉积是主要的生油岩系。享堂组、大通河组和河口组的河道砂坝、湖滩滩砂和水下扇水道砂体是主要的储集层．其中，河道砂坝是最重要的。由于受成岩作用影响，孔隙度和渗透率都较低，裂缝－溶蚀孔隙改善了储层的储集性能。根据沉积特征，提出滨浅湖砂滩和水下扇水道是值得注意的有利储集相带。中侏罗统以上的滨浅湖泥岩和粉砂质泥岩是主要的盖层。

SEDIMENTARY SEQUENCE AND OILGAS SIGNIFICANCE OF THE MIDDLE JURASSIC-LOWER CRETACEOUS IN THE BAZHOU DEPRESSION OF THE MINHE BASIN

he Middle Jurassic-Lower Cretaceous in the Bazhou Depression of the Minhe Basin between Gansu and Qinghai Provinces mainly develops sediments of the meander stream, braided stream, shore-mere lake, subaqueous fan and lacustrine delta. The sediments of the backswamp and lacustrine bay in the Yao ne Formation are main hydrocarbon source rocks.The channel bars, beach sands and subaqueous fan's channel sands in the Xiangtang, Datonghe and Hekou Formations are main reservoirs. The channel bars among them are the most important, however, their porosities and permeabilities are very small, because they have been affected by diagenism. Fissure-dissolution pores have improved the capabilities of these reservoirs. On the basis of sedimentary characteristics, we think that the beach sands and subaqueous fan's channel sands are beneficial reservoirs which merit our attention. The mudstones and silty mudstones of the shore-mere lake factes above Middle Jurassic are main caprocks.