中扬子地区震旦系陡山沱组页岩储层孔隙结构特征

通过氩离子抛光-SEM技术，分析了中扬子地区震旦系陡山沱组页岩储层孔隙类型、孔隙形态、孔径和面孔率特征，探讨了这些孔隙的油气地质意义。研究认为，陡山沱组页岩储层发育有机质孔隙、粒间孔隙、粒内孔隙和微裂缝4种孔隙类型。页岩孔隙形态可分为不规则多边形孔、圆形或椭圆形孔、复杂网状孔、串珠状孔、长条形孔、线状孔6种类型，其中复杂网状孔的连通性最好，有利于压差传递，可提高页岩气的解吸效率和储层的渗透率。页岩孔径为10~2 000 nm，主体范围为20~200 nm，平均面孔率为1.4%~6.2%。不同类型的孔隙能够为页岩气的赋存提供不同尺度的储集空间，微裂缝和粒间孔隙对页岩气的运移最为有利。

Research on Pore Structures of Sinian Doushantuo Formation Shale in Middle Yangtze Area

Research on pore structures of shale gas is important to the study of shale gas evolution. Using the argon-ion milling-SEM technology this paper analyzes the pore type, pore shape, pore diameter and porosity of Doushantuo Formation shale reservoir in middle Yangtze area, and discusses the geological significance of these pores to oil and gas. Research results show that the shale in Doushantuo Formation can be divided into 4 types,i.e. organic pores, inter-granular pores, intra granular pores and microfractures. The pore morphology of shale can be divided into irregular polygon pores, round or oval pores, complex mesh pores, moniliforme pores, long-strip pores and striation pores. The complex mesh pore which has the best connectivity is conducive to the pressure transmission and can improve the desorption efficiency of shale gas and the permeability of reservoir. The shale pore diameter is 10 to 2 000 nm; the main range is 20 to 200 nm; the average porosity is 1.4% to 6.2%. Different types of pores can provide different-scale reservoir spaces for the occurrence of shale gas migration, and micro-fractures and inter granular pores are the most advantageous.