摘要
为了深入研究鄂西地区吴家坪组硅质页岩的储层特征及其含气性,选取利川复背斜袁家槽和黄泥塘剖面样品进行了元素地球化学、有机地球化学、矿物组成、储层物性和超临界甲烷吸附等一系列分析测试,探讨了页岩的孔隙构成和吸附能力的影响因素.认为中孔贡献了吴家坪组页岩86.02%的孔体积和64.26%的比表面积,优势孔隙类型为有机质孔,TOC是页岩吸附能力的主控因素.研究结果表明:吴家坪组硅质页岩形成于深水缺氧的沉积环境,TOC值平均为7.29%,有机质类型以Ⅱ1型为主、成熟度eqvRo为1.91%~1.96%,石英质量分数平均为68.9%,具备页岩气生成和储层改造的优越条件;吴家坪组页岩主要储集空间为有机质孔,其次为矿物晶间孔,粒内孔发育程度最低,不同有机质颗粒的孔隙面孔率差异很大,与有机质的显微组成密切相关,BET比表面积和孔体积分别为6.63~33.12m^(2)/g和0.015~0.047cm^(3)/g,具备良好的页岩气储集条件;采用三元Langmuir模型拟合高温超临界甲烷吸附曲线,60℃时页岩的兰氏体积为2.08~3.96cm^(3)/g,具有较好的吸附性能,吴家坪组页岩的兰氏体积、TOC与BET比表面积三者之间具有良好的正相关性,说明TOC是微观孔隙和气体吸附能力的主要控制因素,有机质通过提供大量的中孔以及微孔来构建吴家坪组硅质页岩的孔隙系统,增加页岩的吸附能力,受强压实作用黏土颗粒排列致密,孔隙变形和闭合,数量减少,随黏土矿物质量分数增加,在一定程度上降低了页岩的比表面积和吸附能力.
In order to study the reservoir characteristics and gas-bearing capacity of the siliceous shales of Wujiaping formation in western Hubei,samples from the Yuanjiacao and Huangnitang profiles in Lichuan synclinorium were selected.A series of analytical tests,including element geochemistry,organic geochemistry,mineral composition,reservoir physical property,and supercritical adsorption,were conducted to explore the influence factors of shale pore constituent and adsorption capacity.It was suggested that mesopores contribute 86.02%of pore volume and 64.26%of specific surface area.The dominated pore type is organic matter pore and TOCis the main factor determining shale adsorption capacity.The results indicated that the Wujiaping formation shale is formed in a deep-water anoxic sedimentary environment.These shales have average TOCvalue of 7.29%,typeⅡ1kerogen,eqvRovalue of 1.91%—1.96%,and average quartz content of 68.9%,indicating favorable condition for shale gas generation and reservoir transformation.The main storage space of the Wujiaping formation shale is organic matter pore,followed by mineral intercrystalline pore and intragranular pore.Plane porosity of different organic matter grains varies greatly,which is closely related to the maceral composition of organic matter.The BET specific surface area and pore volume are in the range of 6.63—33.12m^(2)/g and 0.015—0.047cm^(3)/g,respectively,showing great reservoir condition for shale gas storage.The ternary Langmuir model was used to fit the adsorption curve of hightemperature supercritical methane,and the Langmuir volume is 2.08—3.96cm^(3)/g at experimental temperature 60℃,exhibiting good adsorption property.A good positive correlation exists among Langmuir volume,TOCand BET surface area,indicating TOCis the crucial factor influencing the microscopic pores and gas adsorption capacity.Organic matter provides a large amount of mesopores and micropores to construct shale pore system of Wujiaping formation and therefore increases shale gas adsorption capacity.Due to strong compaction,clay particles are densely arranged,the pores are deformed and closed,and the quantity of clay mineral pores decreases.As the clay mineral content increases,the specific surface area and adsorption capacity of shale are reducing to some degree.
作者
曹涛涛
邓模
刘虎
曹清古
刘光祥
CAO Taotao;DENG Mo;LIU Hu;CAO Qinggu;LIU Guangxiang(Hunan Provincial Key Laboratory of Shale Gas Resource Utilization,Hunan University of Science and Technology,Xiangtan,Hunan 411201,China;Wuxi Research Institute of Petroleum Geology,SINOPEC Petroleum Exploration&Production Research Institute,Wuxi,Jiangsu 214126,China;Sichuan Key Laboratory of Shale Gas Evaluation and Exploration,Chengdu,Sichuan 600091,China)
出处
《中国矿业大学学报》
EI
CAS
CSCD
北大核心
2021年第1期138-153,共16页
Journal of China University of Mining & Technology
基金
国家自然科学基金项目(41820163)
湖南省自然科学基金项目(2018JJ3152)
四川省科技计划项目(2018JZ0003)。
关键词
沉积环境
储层特征
超临界甲烷吸附
吴家坪组
鄂西地区
sedimentary environment
reservoir characteristics
supercritical methane adsorption capacity
Wujiaping formation
western Hubei
