页岩气储层特征及含气性主控因素——以湘西北保靖地区龙马溪组为例  

Characteristics and main controlling factors of shale gas reservoirs:a case from Longmaxi Formation in Baojing area,NW Hunan province

作　　者：胡博文 李斌 鲁东升 罗群[2] 李建新 王一霖 HU Bowen;LI Bin;LU Dongsheng;LUO Qun;LI Jianxin;WANG Yilin(Shenhua Geological Exploration Co.,Ltd.,Beijing 102209,China;The Unconventional Natural Gas Institute,China University of Petroleum(Beijing),Beijing 102249,China)

机构地区：[1]神华地质勘查有限责任公司,北京102209 [2]中国石油大学(北京)非常规天然气研究院,北京102249

出　　处：《岩性油气藏》2017年第3期83-91,共9页Lithologic Reservoirs

基　　金：国家自然科学基金项目"云质岩致密油储层微米-纳米孔喉网络体系及其流体耦合流动机理与流动下限"(编号:41372145)资助

摘　　要：湘西北保靖地区龙马溪组富有机质泥页岩是重要的页岩气勘探层位。为研究其页岩气储层特征和气体赋存规律,利用矿物组分、有机地球化学、物性、含气性、等温吸附、扫描电镜和Nano-CT扫描等测试资料,并结合野外地质调查,分析和探讨了龙马溪组岩相特征、储层特征及储层含气性主控因素。结果表明:龙马溪组发育3种岩相,分别为炭质-粉砂质泥页岩相、炭质泥页岩相、含炭泥质粉砂岩相;储层孔隙类型主要包括粒间孔、溶蚀孔、晶间孔、化石孔、有机质孔和微裂缝,其中裂缝类型主要为构造缝和成岩缝;孔隙按孔径大小可分为微孔、介孔和宏孔,介孔占总孔容的比重最大,其次是微孔,宏孔最少。综合分析认为:微孔孔容、页岩比表面积与甲烷最大吸附量呈正相关性,受控于页岩有机质含量(TOC);微裂缝与页岩含气量也呈正相关性,说明微裂缝的发育程度对页岩含气性具有影响作用。利用Nano-CT扫描结果,认为绝大部分气体流动空间位于有机质孔隙以及微裂缝中。TOC和微裂缝的发育程度是该区龙马溪组页岩气富集的主控因素。The organic-rich shale of Longmaxi Formation is an important shale gas exploration horizon in Baojingarea,NW Hunan Province.In order to study the characteristics of Longmaxi shale gas reservoir and gas occurrencerule,combined with field geologic investigation,the data of mineralogy,organic geochemistry,physicalproperties,gas-bearing property,isothermal adsorption,scanning electronic microscope and Nano-CT,were usedto analyze the characteristics of lithofacies and reservoir and main controlling factors for the gas-bearing propertyof Longmaxi shale.The results show that three types of lithofacies are developed in the Longmaxi Formation,includingcarbon-silty shale,carbonaceous shale and carbon-argillaceous siltstone;the main pore types are intergranularpores,dissolved pores,intercrystalline pores,fossil pores,organic pores and micro-fractures.The main types of fractures are structural fractures and diagenetic fracture.According to the pore size,the reservoir porecan be divided into micropores,mesopores and macropores.Mesopores have the biggest contribution to thewhole pore volume,followed by micropores,and the macropores have the minimum proportion in the wholepore volume.The analysis shows that the microporous volume and surface area of shale have a good positive correlationwith the largest methane adsorption contents,which are both controlled by TOC content in shale.Microfractureshave a good positive correlation with gas content,which indicates that the micro-fracture has an importantinfluence on shale gas-bearing properties.The results of Nano-CT show that most of the gas flow spaces areorganic pores and micro-fractures.The organic matter content and the development of micro-fractures are themain controlling factors for the enrichment of shale gas.

关 键 词：页岩气 孔隙 裂缝 龙马溪组 湘西北保靖地区 

分 类 号：P624[天文地球—地质矿产勘探]