鄂尔多斯盆地南部延长组页岩微观储集空间特征

Characteristics of Yanchang formation shale microscopic reservoir space of in south of Ordos basin

以鄂尔多斯盆地三叠系延长组泥页岩为研究对象,采用岩心观察、薄片鉴定、扫描电镜分析、比表面积及孔径分布分析和等温吸附实验等方法,研究页岩气储层微观储集空间的类型、成因及微观孔隙结构.结果表明：延长组泥页岩微孔隙与矿物的形成与转化存在一定联系,微孔隙中次生孔隙是不稳定矿物溶解和矿物成岩转化过程体积收缩等作用的综合结果.泥页岩孔径分布主要在10~30nm之间,孔径分布特征与页岩比表面积具有较好的对应关系.根据等温吸附—脱附曲线形态,将研究区微孔隙形态分为四类,研究区以第Ⅱ类微孔隙结构为主,页岩气的解吸效率相对较高.该研究结果为明确研究区延长组页岩微观储集空间特征及页岩气赋存机理提供指导.

This paper studied shale of Triassic Yanchang formation of Ordos basin and the types and causes of shale microscopic reservoir space and micro-pore structure were studied by core observation,rock thin section,SEM,specific surface area and pore size distribution analysis and isothermal adsorption test.The research result shows that most of the shale micro pores have a certain connection with the formation and transformation of minerals.The formation of secondary pore is the synthesis results of unstable mineral dissolution and volume shrinkage in the diagenetic minerals conversion.The pore size distribution of shale is mainly between 10~30nm.Based on the isothermal adsorption curve,the micro pore shape of study area is divided into four categories,it is mainly composed by Ⅱcategory the study area.The desorption efficiency of shale gas is relatively high.