泥页岩中有机质:类型、热演化与有机孔隙  

Organic Matter in Shales:Types,Thermal Evolution,and Organic Pores

作　　者：刘贝 Liu Bei(Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education,China University of Geosciences,Wuhan 430074,China;School of Earth Resources,China University of Geosciences,Wuhan 430074,China)

机构地区：[1]中国地质大学构造与油气资源教育部重点实验室,湖北武汉430074 [2]中国地质大学资源学院,湖北武汉430074

出　　处：《地球科学》2023年第12期4641-4657,共17页Earth Science

基　　金：国家自然科学基金项目(No.42202167);湖北省自然科学基金项目(No.2022CFB598)。

摘　　要：泥页岩中的有机质作为石油和天然气的来源,其有机岩石学分类方案仍不明确,传统的煤岩学分类方法并不完全适用于泥页岩中的分散有机质.页岩中有机孔隙是页岩孔隙系统的重要组成部分,在很大程度上控制了页岩的含气量和孔隙度,但其成因及与有机质类型和热成熟度的关系仍存在争议.系统地总结了泥页岩中分散有机质的类型、不同类型有机质的热演化特征以及有机孔隙发育与保存的控制机理,并指出了存在问题及今后研究方向.泥页岩中的分散有机质包含5个显微组分组:镜质体、惰质体、类脂体、动物碎屑和次生有机质,每个显微组分组可再划分为多个显微组分.不同显微组分的成因和生烃潜力不同,有机孔隙发育程度也存在差异.页岩中有机孔隙包括原生孔隙和次生孔隙,后者是主要的有机孔隙类型,其形成与生油型有机质生烃过程密切相关,主要赋存在固体沥青或焦沥青中.有机质类型和热成熟度决定了次生有机孔隙的发育程度,而热成熟度、有机质含量、矿物组成和孔隙压力控制了其保存程度.烃源岩评价中对有机质生烃潜力的研究应建立在对显微组分以及不同显微组分生烃能力充分了解的基础上.非常规油气储层表征中对有机孔隙的研究应充分考虑有机质数量、类型、热成熟度以及页岩矿物学组成,准确地评价有机孔隙对页岩孔隙系统的贡献.Organic matter(OM)in mudstones/shales is the source of oil and gas,the organic petrographic classification of which has not reached a consensus.Traditional coal petrological methods do not fully apply to dispersed organic matter(DOM)in shales.OM-hosted pores are important constituents of the pore system in shale reservoirs,and they,to a large degree,control the gas content and porosity of shales.However,the origin of organic pores and their relationships with OM type and thermal maturity remain controversial.This study systematically summarized the types of DOM in shales,thermal evolution of different types of OM,and factors controlling the formation and preservation of organic pores,and proposed the issues related to DOM study and future research directions.DOM in shales can classified into five maceral groups:vitrinite,inertinite,liptinite,zooclasts,and secondary organic matter,with each group consisting of multiple macerals.Different macerals have different origins,and varying potential of hydrocarbon generation and development of organic pores.Organic pores in shales can be primary or secondary,the latter of which is the dominant type.Secondary organic pores occur in solid bitumen or pyrobitumen,and their development is related to thermal maturation of oil-prone macerals.The development of secondary organic pores is controlled by OM type and thermal maturity,and their preservation depends on thermal maturity,OM content,mineralogical composition of shales,and pore pressure.When conducting source rock evaluation,the hydrocarbon generation potential of OM should be studied based on a good understanding of maceral types,composition,and their hydrocarbon generation potential.In order to accurately assess the contribution of organic pores to the pore system of shale reservoirs,the influence of OM type,content,and thermal maturity should be taken into consideration.

关 键 词：泥页岩 分散有机质 显微组分 热演化 固体沥青 有机孔隙 石油地质 

分 类 号：P588[天文地球—岩石学]