氮气吸附滞后回环定量分析及其在孔隙结构表征中的指示意义——以鄂尔多斯盆地上三叠统延长组7段为例  

Quantitative analysis of nitrogen adsorption hysteresis loop and its indicative significance to pore structure characterization:A case study on the Upper Triassic Chang 7 Member,Ordos Basin

作　　者：宋泽章 阿比德·阿不拉 吕明阳 张月巧[3] 姜福杰[1,2] 刘哲宇 郑伟[1,2] 王夏阳 SONG Zezhang;ABIDE Abula;LYU Mingyang;ZHANG Yueqiao;JIANG Fujie;LIU Zheyu;ZHENG Wei;WANG Xiayang(State Key Laboratory of Petroleum Resource and Prospecting,China University of Petroleum(Beijing),Beijing 102249,China;College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;Research Institute of Petroleum Exploration and Development,PetroChina,Beijing 100083,China)

机构地区：[1]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [2]中国石油大学(北京)地球科学学院,北京102249 [3]中国石油勘探开发研究院,北京100083

出　　处：《石油与天然气地质》2023年第2期495-509,共15页Oil & Gas Geology

基　　金：中国石油科技创新基金项目(2021DQ02-0105);中国石油科技重大专项(2021DJ0404);国家自然科学基金青年基金项目(41802148)。

摘　　要：低温氮气吸附滞后回环的形态和面积可以有效反映多孔介质的孔隙结构及其对吸附气体的滞留效应,但其在页岩孔隙结构定量表征中的作用常被忽视。优选鄂尔多斯盆地上三叠统延长组7段(长7段)页岩为研究对象,综合场发射扫描电镜孔隙结构定性观察、低温氮气吸附孔隙结构定量分析、“滞后回环”定量分析、总有机碳含量(TOC)分析、热解实验、X射线衍射实验等手段,对页岩在低温氮气吸附-脱附实验中能否形成“滞后回环”以及形成的“滞后回环”面积大小的决定因素进行了探索。研究结果表明:①页岩样品在低温氮气吸附-脱附实验中是否能形成滞后回环,与其比表面积、比孔容、黏土矿物含量及孔隙结构分形维数之间存在明显的正相关关系,与总有机碳含量呈明显负相关关系,而与平均孔径大小、孔隙表面分形维数、最高热解峰温和脆性矿物含量等无明显相关关系;②滞后回环的面积大小取决于两端开放的圆柱形孔、墨水瓶孔或平行板孔的发育程度,可借助滞后回环的面积大小来定量评价圆柱形孔、墨水瓶孔或平行板孔占孔隙空间的相对比例;③长7段泥页岩样品中开放的圆柱形孔、墨水瓶孔或平行板孔主要由黏土矿物晶间孔提供,滞后回环面积与泥页岩样品中黏土矿物含量之间存在明显的正相关关系。Low-temperature nitrogen adsorption can form a“hysteresis loop”,whose geometry and area can effectively reflect the pore structure of porous media and its retention effect on adsorbed gas.However,the role of the“hysteresis loop”in quantitative characterization of shale pore structure has often been ignored.The study aims to clarify whether shale can form“hysteresis loop”in low-temperature nitrogen adsorption-desorption experiment and the determinants on hysteresis loop’s area with experiments on the 7th member of the Upper Triassic Yanchang Formation shale(Chang 7 shale)in the Ordos Basin.Various measures are applied in the study,including qualitative observation of pore structure under field-emission scanning electron microscopy(FE-SEM)and quantitative characterization of pore structure by low-temperature nitrogen adsorption test,hysteresis-loop quantitative analysis,total organic carbon(TOC)

关 键 词：滞后回环 氮气吸附 孔隙结构 页岩 延长组 鄂尔多斯盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]