黔西北龙马溪组页岩微观孔隙结构及储气特征  

Characteristics of microscopic pore and gas accumulation on shale in Longmaxi Formation,northwest Guizhou

作　　者：薛冰[1,2] 张金川[1,2] 唐玄[1,2] 杨超[1,2] 陈前[1,2] 满向杰[1] 党伟[1,2] 

机构地区：[1]中国地质大学能源学院,北京100083 [2]国土资源部页岩气资源战略评价重点实验室,北京100083

出　　处：《石油学报》2015年第2期138-149,173,共13页Acta Petrolei Sinica

基　　金：国家自然科学基金项目(No.41102088);贵州省国土资源厅项目(2012GYYQ-001)资助

摘　　要：为了深入研究黔西北地区海相页岩储层微观孔隙特征,选取下志留统龙马溪组页岩进行了氩离子抛光场发射扫描电子显微镜、氮气吸/脱附实验、微孔特征分析以及相关地球化学分析等实验,探讨了微观孔隙对页岩储气特征的影响.实验结果表明：黔西北龙马溪组页岩存在粒间孔、粒内孔、晶间孔、溶蚀孔、化石孔、有机孔、微裂缝7种孔隙类型,其中粒间孔和有机孔最为发育;孔隙结构类型可根据氮气吸/脱附曲线分为3种,即以两端开口的圆筒孔、狭窄的平行板孔和四面开口的锥形平板孔等开放型孔隙为主;微观孔隙孔径分布范围为2～64 nm,峰值集中于2～6 nm.微孔（小于2nm）孔径分布范围为0.4～1.8nm,0.4～1.0nm的微孔对微孔孔容贡献最大.孔容中以中孔（2～50 nm）为主,所占比例为83.1％,微孔和中孔贡献了主要的孔比表面积,微、中孔所占比例分别为20.1％和79.3％.有机碳含量是纳米孔隙发育的主控因素.不同孔隙类型具有不同的气体赋存特点和运移特征,说明纳米孔隙为页岩中气体的赋存和微观运移提供了有利条件.To deeply study micro-pore characteristics of shale reservoirs in Longmaxi Formation,northwest Guizhou,the shale in Longmaxi Formation was selected for experiments including the Argon Ion milling-Field Emission Scanning Electron Microscopy,nitrogen sorption-desorption experiment,micro-pore characteristic analysis and related geochemical experiments.Meanwhile,the influences of micro pores on shale gas accumulation characteristics were discussed.The experimental results show that there are seven kinds of shale micro-pore types in Longmaxi Formation,northwest Guizhou,i.e.,inter-granular pore,intra-granular pore,intracrystalline pore,dissolved pore,fossiliferous pore,organic pore and micro-cracks,of which inter-granular pore and organic pore are most developed.The pore structures can be divided into three types according to nitrogen sorption-desorption curves,i.e.,cylindrical pore with both ends open,narrow parallel-plate pore and conical plate pore with four sides open.The micro-pore diameters are generally ranged in 2-64 nm,and the peak is distributed in 2-6 nm.The diameters of micro-pore （＜2 nm） are ranged in 0.4-1.8 nm,which the 0.4-1.0 nm of micropore diameters dominate the mostly micropore specific surface.The pore volume is mostly occupied by meso-pores （2-50 nm） with the proportion of 83.1％.The micro-pores and meso-pores make a major contribution to pore specific surface area with the proportion of 20.1％ and 79.3％ respectively.The content of organic carbon is the main controlling factor of nano-pore development.Different pore types have different characteristics of gas occurrence and migration,proving that nano-pore provides favorable conditions for the occurrence and micro-migration of shale gas.

关 键 词：黔西北 龙马溪组 下志留统 氩离子抛光-扫描电镜 氮气吸/脱附 孔隙结构 

分 类 号：TE132.2[石油与天然气工程—油气勘探]