湘鄂西地区龙马溪组黑色页岩孔隙结构及分形特征

第30卷12期2018年12月中国煤炭地质COAL GEOLOGY OF CHINA

Vol．30No．12Dec．2018

doi:10．3969/j．issn．1674-1803．2018．12．02文章编号:1674-1803(2018)12-0005-10湘鄂西地区龙马溪组黑色页岩孔隙结构及分形特征

扈金刚1,2,黄 勇1,熊 涛1,唐书恒2,张 彪1,孙鹏杰1

(1．北京大地高科地质勘查有限公司,北京 100040;

2．中国地质大学(北京)海相储层演化与油气富集机理教育部重点实验室,北京 100083)

摘 要:以湘鄂西地区龙马溪组黑色页岩为研究对象,通过进行扫描电镜二低温氮吸附二有机地化和XRD 等实验,分析其孔隙结构和分形特征,并对其影响因素进行了研究三结果表明,黑色页岩中发育有机质孔二粒内孔二粒间孔和微裂隙等四大类孔隙三所有页岩样品均为存在迟滞环的Ⅳ类吸-脱附等温线三迟滞环H2型主要发育墨水瓶状孔隙;迟滞环为H3型,以发育平行板状孔隙为主;并且迟滞环存在H2型和H3型之间的过渡型三介孔对总比表面积和孔体积的贡献最大三有机质热解生烃形成的微孔孔隙丰富了其内部的孔隙发育类型,页岩有机碳含量越高,发育于有机质中的微孔隙所占比例越高,页岩孔隙结构越复杂三与黏土矿物有关的孔隙孔径普遍大于有机质中的孔隙,从而富含黏土矿物的页岩样品中孔隙结构较为简单,分形维数也较小三

关键词:孔隙结构;低温氮吸附;分形维数;龙马溪组页岩

中图分类号:P618．13 文献标识码:A Pore Structure and Fractal Features of Black Shale in Longmaxi Formation ,Western Hunan and Hubei

Hu Jingang 1,2,Huang Yong 1,Xiong Tao 1,Tang Shuheng 2,Zhang Biao 1and Sun Pengjie 1

(1．Beijing Dadigaoke Geological Exploration Co．Ltd．,Beijing 100040;2．Ministry of Education Key Laboratory of Marine Reservoir Evolution and Hydrocarbon Enrichment Mechanism,China University of Geosciences (Beijing),Beijing 100083)Abstract :Taking the black shale in the Longmaxi Formation,western Hunan and Hubei as the subject investigated,through experi-ments of SEM,low temperature nitrogen adsorption,organic geochemistry and XRD,analyzed its pore structure and fractal features,carried out study on their impacting factors．The result has shown that the organic matter pore,intragranular pore,intergranular pore and microfissure four categories of pores have been developed in black shale．All shale samples have existed hysteresis loop category IV

adsorption -desorption isotherms．If hysteresis loop is H2type mainly developed ink -bottle shaped pores,while H3type mainly de-veloped parallel plate shaped pores,and transitional H2to H3type existed．The mesopores have largest contribution to total specific surface area and pore volume．Organic matter pyrolytic hydrocarbon generation formed micropores have enriched internal pore develop-ment types,the high the organic carbon content in shale,the high the proportion of microfissures in organic matter,and the complex the pore structure in shale．The pore size of pores related to clay minerals is generally larger than pores in organic matter,thus pore structure is rather simple of pores in shale samples rich in clay minerals,the fractal dimension also smaller．Keywords :pore structure;low temperature nitrogen adsorption;fractal dimension;shale in Longmaxi Formation 第一作者简介:扈金刚(1989 ),男,河北衡水人,北京大地高科地质

勘查有限公司,工程师,毕业于中国地质大学(北京),

矿产普查与勘探专业,工学博士学位,现主要从事煤

层气二页岩气等非常规天然气勘探开发的研究三

收稿日期:2018-11-20

责任编辑:宋博辇 除少量以溶解状态存在于团块有机质和沥青质中外,页岩气主要以吸附态(微小孔隙)和游离态(中大孔隙)赋存于页岩储层中[1-4],页岩孔隙结构是影响其储气能力和工业开采难易程度的主要因

素三与前人对四川盆地及其周缘富有机质页岩储层

孔隙结构特征进行过大量研究相比[5-15],目前对湘

鄂西地区龙马溪组黑色页岩的孔隙结构和分形特征的研究较少,缺乏必要的研究成果作为该区页岩气勘探开发工作的理论支撑和数据储备三本文以湘鄂西地区下志留统龙马溪组黑色页岩为研究对象,以扫描电镜二低温氮吸附等为主要实验手段,精细表征该套页岩孔隙结构二分形特征及分析其影响因素,以期对评价湘鄂西地区页岩气的资源潜力具有一定的指导意义三1 地质概况研究区位于中上扬子板块的湘鄂西褶皱带构造单元内(图1),区域构造线总体呈北北东 北东 东西向的向北西方向凸出的弧形分布;褶皱形态主万方数据