摘要
为明确桂中坳陷北部下石炭统鹿寨组一段成藏条件,评价区块资源潜力,利用录井、地震、实验测试等手段,系统分析页岩气成藏地质特征,并采用静态法对研究区页岩气资源量进行计算。研究表明:鹿寨组一段页岩有机质丰度中等(TOC含量在0.49%~5.15%)、类型好(有机质类型为II_(1)~II_(2)型)、热演化程度适中(热成熟度在2.2%~2.9%);储层脆性指数高(51%~94%),物性条件较好(孔隙度在3.12%~5.02%,渗透率在0.0005~0.161 mD),孔径多小于400 nm;储层孔隙类型以有机质孔和溶蚀孔为主,孔隙比表面积以微孔贡献为主,孔体积则主要由微孔和介孔贡献,微孔发育主控因素包括TOC和黏土矿物,而介孔发育主控因数为黏土矿物;现场总含气量平均1.73 m^(3)/t,甲烷含量高达95%,为高热值干气;甲烷等温吸附绝对吸附量在1.07~3.67 m^(3)/t,页岩吸附能力强;研究区页岩气藏埋藏深度多在1000~3000 m,顶板黄金组和底板尧云岭组岩性以(泥质)灰岩为主,岩性致密,累计厚度分别可达720 m和490 m,区内逆冲断层封堵性好,构造变形程度较低,岩浆活动较弱,温泉水循环深度多在800~1000 m,水文地质开启程度低。研究区沙坪复向斜页岩气地质资源量为255.2×10^(8) m^(3),技术可采资源量为38.3×10^(8) m^(3),技术可采资源丰度0.45×10^(8) m^(3)/km^(2)。结论认为,桂中坳陷北部残留向斜核部鹿寨组一段页岩生烃基础较优越、储集空间发育、含气性高、保存条件较好、埋深适中及资源丰度较高,是页岩气勘探开发有利目标。
In order to clarify shale gas accumulation conditions of the first member of the Lower Carboniferous Luzhai Formation(Clz~1)in the northern Guizhong depression and evaluate their resource potential,geological characteristics of shale gas accumulations were systematically analyzed based on well logging,seismic data and experimental analyses.Furthermore,shale gas resources in the study area were also revealed using a static method.The results show that the Clz~1 shale is characterized by moderate organic matter abundance(TOC content between 0.49%and 5.15%),well organic matter type(typeⅡ~Ⅱ),and suitable thermal evolution maturity(thermal maturity between 2.2%and 2.9%).The Clz~1 shale reservoirs generally have a relatively high brittleness index at 51%~94%,well porosity and permeability of 3.12%~5.02%and 0.0005~0.161 mD,respectively,and pores with diameters below 400 nm.The shale reservoirs are primarily composed of organic matter related and dissolved pores,and their specific surface area is mainly contributed by micropores,while their pore volume is commonly derived from micropores and mesopores.The development of micropores is simultaneously controlled by TOC and clay mineral contents,whereas that of mesopores is only controlled by clay minerals.The total gas content is 1.73 m^(3)/t on average,with methane proportion of up to 95%(dry gas with high calorific value).The absolute methane adsorption capacity of shale reservoirs primarily ranges from 1.07 m^(3)/t to 3.67 m^(3)/t,indicating a relatively strong adsorption capacity.The burial depth of shale gas reservoirs in the study area is generally 1000~3000 m,and their roof and floor are the Huangjin and Yaoyunling Formations with tight(argillaceous)limestone,corresponding to a cumulative thickness of 720 m and 490m,respectively.The degree of tectonic deformation in the study area is low,and the blocking ability of the thrust fault was strong.Magmatic activity is very weak in the study area.The circulation depth of hot spring water is primarily between 800 m and 1000 m,corresponding to a low degree of hydrogeological opening.The geological resources of shale gas in the Shaping synclinorium of the study area are 255×10^(8) m^(3),with technically recoverable resources of 38×10^(8) m^(3) and technically recoverable resource abundance of 0.45×10^(8) m^(3)/km^(2).In summary,the C_(1)lz^(1) shale in the residual synclinal core of the northern Guizhong depression is a favorable target for shale gas exploration and development,due to its superior hydrocarbon generation basis,well-developed storage space,great gas-bearing capacity,good preservation conditions,moderate burial depth,and relatively high resource abundance.
作者
覃英伦
雷雨
蒋恕
张仁
张鲁川
岑文攀
卢炳雄
QIN Yinglun;LEI Yu;JIANG Shu;ZHANG Ren;ZHANG Luchuan;CEN Wenpan;LU Bingxiong(Guangxi Investment Group Energy Group Co.,Ltd,Nanning 530000,China;Guangxi Investment Group Co.,Ltd,Nanning 530022,China;Key Laboratory of Tectonics and Petroleum Resources,Ministry of Education,China University of Geosciences,Wuhan 430074,China;School of Earth Resources,China University of Geosciences,Hubei Wuhan 430074,China;Geological Survey Institute of Guangxi Zhuang Autonomous Region,Nanning 530023,China;Guangxi Institute of Geological Survey,Nanning 530023,China)
出处
《石油科学通报》
2022年第2期139-154,共16页
Petroleum Science Bulletin
基金
国家自然科学基金(42130803、42102183)
广西广投能源集团有限公司攻关课题(NYHT2020-016)
广西壮族自治区自然科学基金(2018JJB150094)
广西壮族自治区科技厅科技计划-科技基地和人才专项联合资助。
关键词
页岩气
资源潜力
下石炭统鹿寨组
桂中坳陷
shale gas
resource potential
the Lower Carboniferous Luzhai Formation
Guizhong depression
