桂中坳陷下石炭统鹿寨组页岩段碳酸盐矿物发育特征及成因机制  

Development characteristics and genetic mechanism of carbonate minerals in shale member of the lower Carboniferous Luzhai formation in the depression of central Guangxi

作　　者：淡永 邓敏 张庆玉[3] 闫剑飞 聂国权 董红琪 季少聪 熊国庆 卢炳雄 马小林 DAN Yong;DENG Min;ZHANG Qingyu;YAN Jianfei;NIE Guoquan;DONG Hongqi;JI Shaocong;XIONG Guoqing;LU Bingxiong;MA Xiaolin(Chengdu Center,China Geological Survey(Geosciences Innovation Center of Southwest China),Chengdu,Sichuan 610081,China;Key Laboratory of Sedimentary Basin and Oil and Gas Resources,Ministry of Natural Resources,Chengdu,Sichuan 610081,China;Institute of Karst Geology,CAGS,Guilin,Guangxi 541004,China;School of Geography and Planning,Nanning Normal University,Nanning,Guangxi 530001,China;No.4 Geological Team of Guangxi Zhuang Autonomous Region,Nanning,Guangxi 530033,China)

机构地区：[1]中国地质调查局成都地质调查中心(西南地质科技创新中心),四川成都610081 [2]自然资源部沉积盆地与油气资源重点实验室,四川成都610081 [3]中国地质科学院岩溶地质研究所,广西桂林541004 [4]南宁师范大学地理科学与规划学院,广西南宁530001 [5]广西壮族自治区第四地质队,广西南宁530033

出　　处：《中国岩溶》2024年第5期1210-1222,共13页Carsologica Sinica

基　　金：广西重点研发项目“桂中岩溶复杂区页岩气‘甜点’预测技术研发”(桂科AB23026062);广西自然基金项目(2020GXNSFAA297095,2022GXNSFBA035454);四川省科技厅中央引导地方发展专项(2023ZYD0153)。

摘　　要：目前桂中坳陷下石炭统鹿寨组展现出较好的页岩气勘探前景,但页岩中碳酸盐矿物含量较高,异于国内主要页岩气层的碳酸盐矿物含量,其碳酸盐矿物成因及其对页岩气产气的影响未知。文章以桂融页1井及其野外剖面为研究对象,运用X-全岩衍射、岩石薄片鉴定等手段,发现鹿寨组页岩中碳酸盐矿物以方解石为主,含量为5%~80%,平均为30.33%,并含少量白云石(0%~9%),平均为2.1%,碳酸盐矿物主要发育在炭质页岩、钙质泥岩、粉砂质钙质泥岩、生屑炭质泥岩、泥微晶灰岩和泥质灰岩中以及顺层分布的方解石脉、穿层的构造方解石脉中。在此基础上进一步开展阴极发光、碳氧同位素分析,发现碳酸盐矿物成因主要为海水中原地正常沉积成因,其次为海水中随海浪、风暴流打碎后异地搬运成因以及成岩期重结晶成因,水平脉状方解石的形成可能为埋藏期差异压实收缩缝被地层流体充填后过饱和沉淀,而垂向脉状方解石与多期构造活动有关。The Carboniferous was significant for the development of"black strata"in the world.The exploration and development of shale gas in North America first began with the Carboniferous marine shale,and the Carboniferous(Mississippian)Barnett Shale has become one of the most important strata of shale gas production in the world.The distribution of Carboniferous marine shale in China is relatively limited,primarily developed in the Qian–Gui rift basin at the edge of the Yangtze plate.It is roughly distributed in depressions such as central Guangxi–Nanpanjiang in Guangxi,south Guizhou–southwest Guizhou,and central Hunan.In recent years,drilling activities in the Carboniferous depressions,such as Guirongye Well 1 and Qianziye Well 1 have yielded promising shale gas displays.In 2023,Guirongye Well 2 achieved industrial gas flow from the Carboniferous after the compression fracture was completed,indicating favorable exploration prospects.The Carboniferous strata in the Guizhou–Guangxi region are anticipated to become the next significant exploration target in China,following the shale gas of Wufeng–Longmaxi formation.However,drilling in this area revealed a rapid phase transition in the early Carboniferous,unstable distribution of shale,high levels of carbonate minerals within the shale,and the presence of common carbonate rock interlayers.On-site experiments on water invasion and gas logging suggest that shale gas production is influenced by carbonate minerals in the shale.The origins of these carbonate minerals in the shale of this region and their impact on gas production remain unclear.To this end,the Luzhai formation shale of the early Carboniferous in the depression of central Guangxi was selected to analyze the origin of carbonate minerals within the shale.This study aims to provide theoretical reference for predicting distribution of various types of carbonate minerals in the subsequent shale formation,as well as for gas content analysis and the optimization of the lower Carboniferous shale gas"sweet spot"

关 键 词：页岩气 碳酸盐矿物 成因机制 鹿寨组 桂中坳陷 

分 类 号：P618.13[天文地球—矿床学]