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微孔隙(或微裂缝)作为页岩气的储集空间,对于页岩气的研究具有重要的作用。作者挑选了上震旦统-下志留统黑色页岩发育的上扬子地区10条剖面(上奥陶统—下志留统五峰-龙马溪组6条、下寒武统水井沱组2条、上震旦统陡山沱组2条),共20个样品进行场发射扫描电镜的精细扫描分析,初步识别出上震旦统-下志留统黑色页岩中的6种微孔隙(或裂缝)类型及其形成机制:格架孔主要是由碳酸盐岩和硅酸盐岩的颗粒和片状矿物堆砌、叠置而成;溶蚀孔主要与方解石、白云石和长石伴生,受到成岩晚期及埋藏过程中流体的溶蚀而成;生物体腔孔与生物的种类和数量紧密相关,主要由硅藻内部排列规则的孔集合而成;有机质孔的孔隙度与有机质类型和成熟度相关;白云石化孔主要是与方解石的白云石化作用密切相关,但极其少见。裂缝主要分为3种:(1)黏土矿物的脱水作用形成的微裂缝;(2)大片状的矿物与颗粒之间的微裂缝;(3)晶粒之间和颗粒内受到外力作用形成的微裂缝。
Microporosity (or microcrack) as a reservoir space for shale gas plays an important role in the study of shale gas. The authors selected 10 profiles of the Upper Yangtze region, Upper Ordovician, Lower Silurian, Wufeng-Longmaxi Formation, and the Lower Cambrian Shuijingtuo Formation, , And 2 in the Uppermost Sinian Doushantuo Formation). A total of 20 samples were analyzed by field emission scanning electron microscopy (SEM), and six kinds of microporosity in the upper Sinian-Lower Silurian shale Cracks) types and their formation mechanism: grid hole is mainly composed of carbonate and silicate particles and flaky minerals pile up, stacked; dissolved pores mainly associated with calcite, dolomite and feldspar, by diagenesis Late stage and burial process of fluid erosion; organism cavity and organism species and quantity are closely related, mainly by the arrangement of regular diatoms within the pores formed; organic matter pore porosity and organic matter type and maturity; Baiyun Petrification pores are mainly closely related to dolomitization of calcite, but are extremely rare. The cracks are mainly divided into three types: (1) micro-cracks formed by dehydration of clay minerals; (2) micro-cracks between large-scale minerals and particles; (3) formation of external cracks between grains and within grains Micro-cracks.