四川盆地下古生界黑色页岩纳米孔隙形态的影响因素及其地质意义  

The Control Factors and Geological Implications of the Nanopore Morphology of the Lower Paleozoic Black Shales in the Sichuan Basin, China

作　　者：焦堃[1,2] 谢国梁 裴文明 刘树根[1,2] 刘向君[4] 康毅力[4] 邓宾[1,2] 庞谦 刘文平[5] 罗超[5] JIAO Kun;XIE Guoliang;PEI Wenming;LIU Shugen;LIU Xiangjun;KANG Yili;DENG Bin;PANG Qian;LIU Wenping;LUO Chao(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China;College of Energy,Chengdu University of Technology,Chengdu 610059,China;Nanjing Institute of Environmental Sciences,Ministry of Environmental Protection,Nanjing 210042,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China;Exploration and Development Research Institute of Southwest Oil&Gas Field Company(CNPC),Chengdu 610051,China)

机构地区：[1]油气藏地质及开发工程国家重点实验室(成都理工大学),成都610059 [2]成都理工大学能源学院,成都610059 [3]生态环境部南京环境科学研究所,南京210042 [4]油气藏地质及开发工程国家重点实验室(西南石油大学),成都610500 [5]中国石油西南油气田公司勘探开发研究院,成都610051

出　　处：《高校地质学报》2019年第6期847-859,共13页Geological Journal of China Universities

基　　金：国家自然科学基金青年基金项目（41702145）;四川省科技厅应用基础项目（2018JY0437）;四川省科技计划项目（15ZC1390）;油气藏地质及开发工程国家重点实验室（成都理工大学）开放基金资助项目（PLC20180203）联合资助

摘　　要：以场发射扫描电镜与Pores and Cracks Analysis System(PCAS)图像处理软件为主要研究手段,以形状系数为孔隙形态表征参数,并选取低压N2吸附等为辅助研究手段,对四川盆地及周缘地区的典型钻井A-D井龙马溪组及筇竹寺组黑色页岩中纳米孔隙的形态特征进行定量研究。研究发现黑色页岩纳米孔隙形态受孔隙类型(赋存位置)、有机质显微组分、地层埋藏深度、热成熟度及孔隙尺寸等因素综合控制。具体体现在:(1)有机质孔、粒间孔和粒内孔所占比例、孔径分布与孔隙形态具有明显差异,反映这三类孔隙的演化受成岩作用的影响不同。(2)固体沥青纳米孔隙比其他显微组分中的纳米孔隙更加规则。(3)与埋藏深度密切相关的压实作用很可能会在垂向上压缩孔隙,一方面令孔径缩小,另一方面让孔隙形态往狭长–裂缝形发展。(4)有机质孔形态随热成熟度升高总体上会变得更加规则,但这种趋势可能会被孔隙间的合并及压实作用等破坏。(5)面积更小的孔隙形态往往比面积更大的孔隙更规则。初步研究显示固体沥青纳米孔隙形态代表着高过成熟页岩气储层中主体储集空间所处压力环境,但固体沥青纳米孔隙形态随孔隙压力的演化模式及利用固体沥青纳米孔隙形态表征其所在层系异常高压维持状况及页岩气保存状况的可能性尚需进一步研究。The nanopore characteristics especially the pore morphology of Longmaxi and Qiongzhusi black shales of typical wells in Sichuan Basin and its periphery such as Well A to D were analyzed by Field emission scanning electron microscopy(FESEM),Pores and Cracks Analysis System(PCAS)—a SEM image processing software,and low-pressure N2 adsorption was used as a secondary tool.The form factor was the major parameter to characterize the pore shapes in this study.The results show that the nanopore morphology of black shales are controlled by the nanopore type(occurrence location of nanopores),maceral type,burial depth,thermal maturity of organic matters and the pore sizes.Here are the details:(1)The ratios,pore sizes,form factors of interparticle pores,intraparticle pores and organic matter pores are quite different,which shows that the evolution of the three types of nanopores have different paths.(2)The pore shapes of nanopores in solid bitumen are more regular than those in other macerals.(3)The compaction related to the burial depth can compress the pores vertically,to reduce the pore sizes and change the pore shapes from round or elliptical-shaped to slit-shaped.(4)The nanopores shapes of organic matter pores generally tend to be more regular with the increase of thermal maturity,although the trend may be disrupted by the compaction and the merging of nanopores.(5)The nanopores that have smaller sizes tend to have more regular pore shapes.The preliminary study shows that the morphology of nanopores in solid bitumen may indicute the pressure environment of main reservoir space in the high-over mature shale gas reservoirs.However,the pattern of the pore morphology evolution in solid bitumen,and the possibility of using form factor of nanopores in solid bitumen to evaluate the overpressure and shale gas preservation condition in potential gas shales still need further research.

关 键 词：页岩气储层 孔隙结构 形状系数 孔隙演化 成岩作用 

分 类 号：P618.13[天文地球—矿床学]