摘要
鄂西地区是长江中下游地区页岩气勘探开发的重点区域,其中震旦系、寒武系等层系均获页岩气流,因此,对其储层微观孔隙结构特征及其影响因素进行研究具有十分重要的意义。通过对研究区页岩样品进行电场发射扫描电子显微镜(field emission scanning electron microscope,FE-SEM)观察、总有机碳(total organic carbon,TOC)含量测定、全岩及黏土X-衍射分析及其岩石物性等的分析,明确了研究区储层孔渗特征及储集空间类型、有机质丰度及成熟度、矿物组成等。研究表明:牛蹄塘组页岩核磁总孔隙度及渗透率均大于陡山沱组页岩,陡山沱组页岩有机质孔隙发育较好且发育更多白云石晶间孔,部分层段发育方解石溶蚀晶锥及溶蚀坑洞;TOC含量及有机质热演化程度与有机质孔隙负相关;矿物组分中,石英及长石含量与核磁总孔隙度正相关,而白云石含量与其负相关,黏土矿物与核磁总孔隙度的相关性并不明显;此外,核磁总孔隙度与深度负相关,表现在随深度的加深,核磁孔隙度总体呈波动下降趋势。分析认为:矿物组分、有机质丰度及热演化程度、埋藏深度是影响页岩储集能力的重要因素,有机质的富集有利于页岩气的生成与吸附,脆性矿物的存在提高了储层的脆性,有利于储层的增产改造;埋藏深度影响储集空间的保存条件优劣。
Western Hubei is the key area for shale gas exploration and development in the middle and lower reaches of the Yangtze River.Shale gas flow is obtained in Sinian and Cambrian Strata.Therefore,it is of great significance to study the micro-pore structure and its influencing factors of the reservoir.Through methods of field emission scanning electron microscope(FE-SEM)observation,total organic carbon(TOC)content determination,and X-ray diffraction analysis of whole rock and clay and analysis of rock physical properties of shale samples in the study area,pore-permeability characteristics and reservoir space types,organic matter abundance and maturity,mineral composition of the reservoir in the study area were defined.The results show that the total nuclear magnetic porosity and permeability of Niutitang Formation shale are higher than those of Doushantuo Formation shale.Doushantuo Formation shale has more dolomite intergranular pore,calcite cone and dissolution pit in some sections.TOC content and thermal evolution degree of orga-nic matter are negatively correlated with organic matter pore,and quartz and feldspar content in mineral components are positively correlated with total nuclear magnetic porosity.The relationship between dolomite content and total porosity is negative,while the correlation between clay minerals and total porosity is not obvious.In addition,total porosity and depth are negatively correlated,which shows that with the deepening of depth.The overall nuclear magnetic porosity fluctuates and decreases.The analysis shows that all factors such as mineral composition,organic matter abundance,thermal evolution degree and burial depth are important factors affecting shale reservoir capacity,organic matter enrichment is conducive to shale gas generation and adsorption,brittle minerals improve the brittleness of the reservoir,is conducive to reservoir stimulation and transformation,and burial depth affects the preservation conditions of the reservoir space.
作者
谢婷
李琦
王向华
于伟欣
XIE Ting;LI Qi;WANG Xiang-hua;YU Wei-xin(Ocean Sciences College, China University of Geosciences (Beijing), Beijing 100083, China;Key Laboratory of Unconventional Oil & Gas Geology, China Geological Survery, Beijing 100029, China)
出处
《科学技术与工程》
北大核心
2020年第32期13148-13157,共10页
Science Technology and Engineering
基金
国家自然科学基金(41576066)。
关键词
微观孔隙类型及特征
矿物组分
有机质丰度
热演化程度
埋藏深度
micropore type and characteristics
mineral composition
organic matter abundance
thermal evolution degree
burial depth
