鄂尔多斯盆地东缘煤系伴生泥页岩孔隙特征及主控因素  

Pore characteristics and main controlling factors of mud shale in coal-bearing strata of eastern Ordos Basin

作　　者：陈跃[1] 马东民[1] 吴圣 李新虎[1] 方世跃[1] 郭晨[1] 

机构地区：[1]西安科技大学地质与环境学院,陕西西安710054 [2]贵州天然气能源投资股份有限公司,贵州贵阳550081

出　　处：《天然气地球科学》2018年第2期189-198,共10页Natural Gas Geoscience

基　　金：国土资源部公益性行业科研专项(编号:201311015);西安科技大学博士科研启动金项目(编号:6310116 056);西安科技大学科研培育基金项目(编号:6310217023)联合资助

摘　　要：鄂尔多斯盆地东缘煤系伴生泥页岩广泛发育,页岩气资源潜力大,加强该区泥页岩孔隙特征研究对实现煤层气、页岩气合探共采具有重要意义。通过对研究区山西组、太原组泥页岩样品进行系统的SEM观察、孔渗测试、低温液氮吸附实验、有机地球化学测试及X-射线衍射矿物分析,详细分析了泥页岩孔隙发育特征及主控因素。研究表明:泥页岩中发育的孔隙类型主要有粒间孔、晶间孔、铸模孔、次生溶蚀孔和有机质孔,微裂缝主要发育在脆性矿物晶体间、晶体内和黏土矿物颗粒间,宽度一般为数十纳米;泥页岩孔隙度为1.05%~1.59%,渗透率为(0.001~0.142)×10^(-3)μm^2,山西组泥页岩孔渗性略好于太原组;孔隙以微孔和中孔为主,中孔提供了主要的吸附空间,孔隙形态以开放透气型孔隙为主;有机碳含量、有机质成熟度和无机矿物是影响泥页岩孔隙发育的主要因素,有机碳含量增加,有效孔隙减少,因为成熟度较低时,有机质生成的残留烃可能堵塞了部分较小孔隙;黏土矿物内部及颗粒之间、晶层之间可形成大量微孔及中孔,增加了储集空间,石英矿物可形成较大孔隙和裂缝,改善了泥页岩的渗透性。Since the shale gas resource potential is very considerable and the mud shale in coal-bearing strata developed broadly in eastern Ordos Basin,enhancing the research of pore characteristics of the mud shale is significant in coalbed methane and shale gas joint exploration and development.In this paper,the pore characteristics and main controlling factors of the mud shale in Shanxi and Taiyuan Formations of the study area were analyzed in detail through systematic experiments such as SEM observation,porosity and permeability measurement,low-temperature nitrogen adsorption,organic geochemistry test and X-ray diffraction mineral analysis.The results show that the pore genetic types in mud shale are mainly intergranular pores,intracrystalline pores,moldic pores,secondary dissolution pores and organic pores,and the micro-fractures mainly develop in crystals and between crystals of brittle minerals and between clay mineral particles with a width of tens nanometers.The porosity of mud shale ranges from 1.05% to 1.59% and its permeability ranges from 0.001×10^-3 to 0.142×10^-3μm^2.In addition,the porosity and permeability of mud shale in Shanxi Formation are better than that in the Taiyuan Formation.Micropores and mesopores dominate the mud shale pores and the mesopores provide most space for gas adsorption.Most of them pores are open and ventilate.The total organic carbon content,maturity and inorganic minerals are the main controlling factors of the pores development in mud shale.The efficient pores decrease as total organic carbon content increases,because the residual hydrocarbon generated from organic matter may block some small size pores in low maturity mud shale.A large number of micropores and mesopores develop within and between clay mineral particles,resulting in increasing reservoir space.Besides,quartz minerals are favorable for the development of big size pores and fractures that can improve the permeability of mud shale.

关 键 词：鄂尔多斯盆地 泥页岩 孔隙特征 主控因素 

分 类 号：TE122.2[石油与天然气工程—油气勘探]