Beginning with a review of the history of research on microscopic shale reservoir space

this paper presents the status and prospect of research on microscopic reservoir space of shale gas reservoirs in an attempt to improve the classification system and theory of microscopic pores of shale gas reservoirs.The study of the microscopic shale reservoir space can be divided into a random observation and exploratory stage in the earlier period and a stage of the establishment of conceptual system and its application in the recent period.There are lots of methods for classifying microscopic pores of shale reservoir

among which there are three most typical comprehensive classification schemes

namely pore size-based

pore occurrence-structure-based and pore origin-based schemes.However

there are no unified standards and terminologies for their classification.The study of the evolution of microscopic shale reservoirs is becoming more quantitative.The controlling factors for the development of microscopic pores are complex.The sedimentary environment

structural background

lithology and mineral components control the types of primary pores and the degree of their development.The total organic carbon(TOC)and the types of kerogen influence the development of pores within organic matters.The diagenetic stages directly control the development and evolution of different microscopic pores.In light of the status of study of microscopic shale gas reservoirs

a propose is brought forward here to further improve the classification standard of microscopic pores

so as to establish a scientific

objective

comprehensive and systematic microscopic reservoir classification and evaluation system.A quantitative study of the controlling factors needs to be strengthened to define the correlation of controlling factors and different microscopic pores.In addition

testing methods must be improved progressively for further enlarging the scope and enhancing the precision of measurement

realizing direct

accurate and stereo display of the microscopic pore space of shale reservoirs.