Abstract: Shale serves as both hydrocarbon source rock and reservoir of shale gas.The microscopic features of the Wufeng and Longmaxi Fms shale in Southeast Sichuan Basin such as organic matters,inorganic minerals and pores are described with the technology of Argon ion milling and scanning electron microscop.The organic matters and the pores are regarded as a source-reservoir system to analyze the relationship between their spatial distribution and temporal evolution.The research shows that organic pores are more important than inorganic mineral pores in respect of hosting shale gas,and migrated organic matters develop more pores than in-situ organic matters.Inorganic mineral pores play an important role in the formation of shale gas by hosting abundant migrated organic matters.With plentiful rigid mineral grains such as quartz,the Wufeng and Longmaxi Fms shales had a hard intergranular pore system of inorganic minerals with high porosity,big pores and good connectivity in hydrocarbon generation stage,which can preserve abundant migrated liquid organic matter(oil).The migrated organic matters were stored in intergranular pores among rigid grains and then evolved into solid organic matter with organic pores by exsolution of gaseous hydrocarbons,and the gas filled the organic pores.This is the most favorable source-reservoir matching relation for the generation and enrichment of shale gas.Most of the intraplatelet pores in clay mineral aggregates had been lost in the early diagenetic stage,while a small amount of organic matters with organic pores were preserved under the support of cements and fluid pressure between the platelets.Pyrite aggregates form intergranular and intercrystal pores,part of which can preserve organic matter and organic pores with smaller size,but their total amount is limited.

Key words: organic pore, migrated organic matter, relationship of source and reservoir, Wufeng Formation, Longmaxi Formation, shale, Southeast Sichuan Basin