可溶有机质对表征页岩储层特性的影响  

Influence of Soluble Organic Matter on Characterization of Shale Reservoir

作　　者：潘磊[1,2] 肖贤明[1] 周秦[1] 

机构地区：[1]中国科学院广州地球化学研究所,有机地球化学国家重点实验室,广东广州510640 [2]中国科学院大学,北京100049

出　　处：《天然气地球科学》2015年第9期1729-1736,共8页Natural Gas Geoscience

基　　金：国家重点基础研究发展计划(“973”)项目(编号:2012CB214705);国家自然科学基金(编号:41321002);中国科学院战略性先导科技专项B(编号:XDB10040300)联合资助

摘　　要：成熟度处于"生油窗"范围的页岩含有一定数量的残余可溶有机质,其对页岩储层特性的表征具有重要影响。对取自四川盆地西北缘的2件上二叠统大隆组页岩,采用二氯甲烷与三氯甲烷进行了抽提处理,对去除可溶有机质前、后的页岩开展了有机地球化学、矿物组成、孔隙结构(比表面积、孔容)等储层特性对比研究。结果表明:抽提后样品的TOC、S1、S2、IH等热解参数呈现降低的趋势,但其矿物组分没有变化,保持了页岩原有孔隙结构特征。可溶有机质占据一定孔隙空间,阻碍了孔隙间的连通性。抽提后的页岩测定的比表面积和孔容变大。页岩样品中残余可溶有机质主要分布于微孔及较小的介孔中,并受成熟度水平的制约。对于低成熟度页岩样品,可溶有机质主要赋存于小于5nm有机质孔隙中。对于中等成熟度页岩样品,微孔及小于20nm介孔成为主要的储集空间。Shale with a maturity within ＂oil window＂contains a certain amount of residual soluble organic matter.This soluble organic matter will have an important influence on the characterization of shale reservoir.In this study,two shale samples were collected from the Upper Permian Dalong Formation in the northwestern margin of Sichuan Basin.Their geochemistry,mineral composition,pore structure（surface area and pore volume）were investigated before and after removing soluble organic matter（SOM）by the extraction with dichloromethane or trichloromethane.The results show that the TOC,S1,S2,and IHof the extracted samples decrease obviously,but the mineral composition has no significant change as compared with their raw samples,thus the original pore structure is thought to be unaltered from the extraction.SOM occupies pore volume and hinders pore connectivity,and the extraction greatly increases the surface area and pore volume of the samples.The residual SOM in the shale samples occur mainly in the micropore and small mesopore,and their occupied pore size range seems being constrained by the maturity.For the shale samples with lower maturity,SOM is mainly hosted in organic pores with diameter less than 5nm.For the shale samples with moderate maturity,micropores and some mesopores ranging between 2nm and 20 nm are the main storage space for the SOM.

关 键 词：可溶有机质 页岩油气 储层特性 孔隙结构 

分 类 号：TE122.2[石油与天然气工程—油气勘探]