浙西荷塘组页岩孔隙结构及分形特征研究  

Pore structure and fractal features of Hetang formation shale in western Zhejiang

作　　者：付常青[1,2] 朱炎铭[1,2] 陈尚斌[1,2] 

机构地区：[1]中国矿业大学煤层气资源与成藏过程教育部重点实验室,江苏徐州221008 [2]中国矿业大学资源与地球科学学院,江苏徐州221116

出　　处：《中国矿业大学学报》2016年第1期77-86,共10页Journal of China University of Mining & Technology

基　　金：国家基础研究发展计划(973)项目(2012CB214702);国家自然科学基金项目(41272155)

摘　　要：运用低温N2和CO2等温吸附、高压压汞及FE-SEM观察,采用分形几何原理,对浙西荷塘组页岩孔隙结构及分形特征进行研究,论述了孔隙结构对页岩储渗条件的影响,并揭示了孔隙结构的影响因素.结果表明：浙西荷塘组页岩矿物基质孔及裂缝孔属渗流孔,有机质孔属吸附孔,因有机质孔面孔率高,而矿物基质孔及裂缝孔面孔率低,使其利于吸附气的富集而欠缺游离气存储空间以及气体的渗流通道;荷塘组页岩孔隙结构大致可分为3类,由于与页岩气渗流密切相关的10010 000nm孔隙基本不发育,造成页岩气运移连通性与渗流条件明显较差.页岩孔径大于25nm的孔隙最具多样性,孔隙结构最复杂,425nm次之,24nm最简单.当孔径大于25nm时,孔隙结构复杂程度与TOC含量呈正相关关系,当孔径小于25nm时,呈负相关关系;孔隙结构复杂程度与黏土矿物含量均呈负相关关系,与脆性矿物含量均呈正相关关系.Using low-temperature N2 and CO2adsorption,high-pressure mercury injection and FE-SEM observation,this paper analyzed the pore structure and fractal features of Hetang formation shale in western Zhejiang on the basis of fractal geometry principle,and discussed the influence of pore structure on shale reservoir permeable conditions,also the factors influencing the pore structures was revealed.The results indicate that mineral matrix pores and fracture pores are seepage pores;organic matter pores belong to adsorption pores.Because of the high surface porosity of organic matter pores,and the low surface porosities of mineral matrix pores and fracture pores,the shale is easy to enrich adsorbed gas,but lack free gas storage space and gas seepage channels.The pore structure of Hetang formation shale can be subdivided into three categories.The 100—10 000 nm pores,which are intimately related to shale gas seepage,are undeveloped,and lead to the poor conditions of shale gas migration connectivity and seepage.The pores,whose diameters are over 25 nm,have the most diverse and complex pore structure,with pores of 4to 25 nm ranking the second,and those of 2to 4nm the simplest instructure.When pore diameter is over 25 nm,the pore structure complexity is positively correlated with the organic carbon content.When the pore diameter is less than 25 nm,the organic carbon content is negatively correlated with the complexity of the pore structure.Moreover,the pore structure complexity has negative correlation with clay mineral content,but positive correlation with brittle minerals content.

关 键 词：孔隙结构 分形 荷塘组 浙西 

分 类 号：TE122.2[石油与天然气工程—油气勘探]