有机质生烃对纳米有机孔隙形成演化的影响  

Effects of Hydrocarbon Generation on the Occurrence of Organic Nanopores during Thermal Maturity of Organic Matters

作　　者：张旭[1] 王琳霖 蔡苏阳 张吉振 李豫 吴陈君 赵娅 肖七林[1] Zhang Xu;Wang Linlin;Cai Suyang;Zhang Jizhen;Li Yu;Wu Chenjun;Zhao Ya;Xiao Qilin(Key Laboratory of Exploration Technologies for Oil and Gas Resources,Ministry of Education,Yangtze University,Wuhan 430100,China;Petroleum Exploration&Production Research Institute,SINOPEC,Beijing 100083,China)

机构地区：[1]长江大学油气资源与勘探技术教育部重点实验室,湖北武汉430100 [2]中国石化石油勘探开发研究院,北京100083

出　　处：《地球科学》2024年第9期3292-3305,共14页Earth Science

基　　金：国家自然科学基金项目(No.42073066);长江大学油气油气资源与勘探技术教育部重点实验室开放基金重点项目(No.PI2021-05).

摘　　要：纳米有机孔隙的发育情况在一定程度上关系到非常规天然气藏的经济效益,但有机质生烃对其形成演化的影响尚需深入研究,本文利用封闭热‒压模拟实验系统对鄂尔多斯盆地二叠系低熟腐殖煤样进行了生烃热模拟实验.基于TOC、岩石热解、气体吸附和扫描电镜观测等结果,刻画了低熟‒过熟不同阶段,煤样内不同类型纳米孔隙形成演化特征,探讨了有机质生烃对有机孔隙发育的影响及其程度.结果显示:低熟‒成熟干酪根初次裂解阶段,有机质颗粒内纳米有机孔隙不发育;高熟阶段中期‒过熟阶段早期,烃类二次裂解导致不同类型有机孔隙大量发育;过熟阶段中‒晚期,芳环缩聚反应促进了有机孔隙发育,尤其是孔径小于2 nm的有机孔隙强烈发育.可见,高演化阶段烃类二次裂解和芳环缩聚反应是有机质颗粒内有机孔隙形成的主要途径.该研究对深入理解沉积盆地深层页岩气和煤层气富集机理具有指导意义.The development of organic nanopores is to some extent related to the economic benefits of unconventional natural gas reservoirs,but the influence of organic hydrocarbon generation on its formation and evolution needs in-depth study.In this paper,hydrous pyrolysis experiments were conducted on a Permian humic coal with low thermal maturity from the Ordos basin.The experimental results of TOC,Rock-Eval,gas adsorption and scanning electron microscope observation for the fresh and cocked coal samples are utilized to delineate the formation and evolution process of various nanopores within the fresh and cocked coal samples,and hence achieve a better understanding of the effects of hydrocarbon generation on the occurrence of organic nanopores from the low mature to overmature stages.The experimental results show that organic nanopores within the organic particles of pyrolyzed coal samples cannot be detected at the low mature to mature stages during which petroleum hydrocarbons were generated mainly by kerogen primary cracking.At the middle of high mature to the early of overmature stages,hydrocarbon generation from the secondary cracking of early formed crude oils resulted in the significant occurrence of various organic nanopores;At the middle to late of overmature stage,the polycondensation of aromatic rings within coal samples promoted the intensive formation of organic nanopores,in particular those with pore size<2 nm.Accordingly,hydrocarbon secondary cracking and the polycondensation of aromatic rings within the pyrolyzed coals at high thermal maturity levels play a major role in the formation of organic nanopores.This study should be helpful to improving our understanding of the enrichment mechanisms for the deeply buried shale gas and coalbed methane.

关 键 词：有机质生烃 纳米有机孔隙 腐殖煤 热模拟实验 页岩气 煤层气 石油地质. 

分 类 号：P624[天文地球—地质矿产勘探]