川东地区二叠系海相页岩有机质富集对有机质孔发育的控制作用  

Control of organic matter enrichment on organic pore development in the Permian marine organic-rich shale,eastern Sichuan Basin

作　　者：王鹏威 刘忠宝[1] 张殿伟[1] 李雄[2] 杜伟[1] 刘皓天[2] 李鹏 王濡岳 WANG Pengwei;LIU Zhongbao;ZHANG Dianwei;LI Xiong;DU Wei;LIU Haotian;LI Peng;WANG Ruyue(Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 102206,China;Exploration and Production ResearchInstitute,Jianghan Oilfield Company,SINOPEC,Wuhan,Hubei 430070,China)

机构地区：[1]中国石化石油勘探开发研究院,北京102206 [2]中国石化江汉油田分公司勘探开发研究院,湖北武汉430070

出　　处：《石油与天然气地质》2023年第2期379-392,共14页Oil & Gas Geology

基　　金：国家自然科学基金面上项目(42272143);中国石油化工股份有限公司科技攻关项目(P22137)。

摘　　要：有机质的丰度、显微组分及微观赋存方式等多种因素对海相页岩中有机质孔隙的发育具有重要控制作用,但相关研究目前仍较为缺乏。基于有机地球化学与有机岩石学分析、扫描电镜、有机质能谱测试等技术手段,对川东地区二叠系茅口组和吴家坪组过成熟海相页岩有机质丰度(TOC)、有机显微组分及有机质赋存方式开展系统对比分析,探讨了有机质富集对有机质孔隙发育的控制作用,并建立了有机质孔隙发育演化模式。研究结果表明:①吴家坪组和茅口组虽均具有“TOC高和原始组分以藻类体为主”的特征,但有机质的赋存方式存在差异。茅口组TOC相对较高,有机质以顺层富集和局部富集等方式赋存;吴家坪组TOC相对较低,有机组分中见结构镜质体和无结构镜质体,有机质以分散或局部富集等方式赋存。②有利的原始有机组分类型的存在是有机质孔隙发育的前提,藻类体等腐泥组分中发育丰富的有机质孔隙,而镜质体等腐殖组分中有机质孔隙不发育。TOC控制了有机质孔隙的发育程度,在一定范围内,TOC越高,有机质孔隙越发育。有机质赋存方式影响有机质孔隙的保存,分散型有机质赋存在脆性矿物格架之内,有机质孔隙保存好;局部富集型和顺层富集型有机质边缘无有效格架支撑,抗压实能力较弱,有机质孔隙保存条件差。Organic matter abundance,macerals and occurrence that have been suggested to significantly control upon pore development in marine shales have not been well studied.Guided by organic geochemistry,organic petrology and other theoretical methods,this study is focused on a systematic analysis and comparison of the abundance,macerals and occurrence of organic matter in the overmature marine shales in the Permian Maokou and Wujiaping Formations at the eastern Sichuan Basin through scanning electron microscope observation and energy spectrum testing among others,to discuss the control of organic matter enrichment on organic pore development in shales and establish an evolution model for the pores.The following results are obtained.Both the Maokou and Wujiaping marine shales are characterized by“high organic matter abundance(TOC)and predominance of algae in their primitive components”.However,they also have some differences in respect of organic matter occurrence.The Maokou Formation shale has relatively higher TOC,with organic matter enriching along bedding or at local position.The Wujiaping Formation shale has relatively lower TOC,with organic matter containing structural vitrinite and structureless vitrinite enriching dispersively or locally.The existence of favorable primitive organic components are a prerequisite for the pore development.Pores are mostly developed in sapropel compositions such as algae but are rarely found in vitrinite.TOC is the key to the pore development.Within a certain range,TOC is positively correlated with organic porosity.The organic matter occurrence influences the pore preservation.Pores are well preserved in dispersed organic matter within brittle mineral framework.The organic matter enriched locally or along bedding usually has less pores preserved under compaction due to a lack of effective framework support.

关 键 词：有机质丰度 有机显微组分 有机质孔隙 海相页岩 二叠系 四川盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]