鄂尔多斯盆地南东部山二段三亚段致密砂岩气藏成藏主控因素

Main Controlling Factors for Tight Sandstone Gas Reservoir Accumulation in P_1s_2~3 of Shanxi Formation in the East of Southern Ordos Basin

从研究区（鄂尔多斯盆地南东部）主力气层下二叠统山西组二段三亚段（P1S2^3）成藏基本条件入手，发现该区烃源岩呈广覆式分布，有机质含量高，普遍达到过成熟阶段。储层孔隙度和渗透率较低，填隙物含量较高，储集空间以次生溶蚀孔隙为主。中二叠统上石盒子组（P2sh5～8）泥质岩类作为该区的区域盖层普遍存在欠压实现象，封闭能力强。气藏平面分布上受控于烃源岩、砂体及构造3个因素．表现出源内成藏、砂体控藏及构造补充成藏3种形式。

The basic hydrocarbon accumulation conditions in the critical gas reservoirs of P1s32of Shanxi Formation were analyzed,it was found out that source rocks were widely distributed with high organic matter content,it was generally at over-matured stage.Reservoir porosity and permeability were lower,the content of matrix was higher,and secondary solution pores were the main reservoir spaces.The mudstone of Upper Shihezi Formation,which was recognized as the regional caprock,was generally under-compacted with high sealing ability.The plane distribution of gas reservoir is controlled by source rock,sand body and its structure,there are three forms of gas accumulation,including accumulation within the source rock,sand body controlled accumulation and structure supplementary accumulation.