摘要
利用露头及岩芯等资料,应用沉积学、矿物学和有机地化分析方法,对该地区牛蹄塘组页岩沉积展布及页岩气储集特征进行了系统研究。划分了牛蹄塘组页岩7个主要岩相,依据沉积构造、岩相特征和有机质含量等建立了页岩储层沉积微相划分依据,并划分出深水陆棚相、半深水陆棚相和浅水陆棚相3种沉积亚相,深水陆棚相页岩有机地化条件良好,为富有机质页岩发育的最有利相带。页岩储集空间主要为基质孔隙,孔隙度平均为3.8%,以低于50 nm的无规则孔为主。页岩中的裂缝多被方解石充填,未提供有效的储集空间,同时对页岩气的保存产生了一定的破坏作用。氮气吸附及SEM分析结果表明,页岩孔隙发育受多因素影响,总孔体积随TOC含量、黏土矿物和黄铁矿含量增高有增大的趋势,但相关系数均较低,值得注意的是黄铁矿与孔隙体积的相关系数相对较高,表明黄铁矿对页岩孔隙发育具有积极作用。富有机质页岩具有较强的吸附能力,其吸附能力的大小主要受TOC含量的控制。
Based on outcrops and core data, the sedimentary distribution and reservoir characteristics of shale gas reservoir of Niutitang formation in Northwest Hunan were studied by analyzing sedimentology, mineralogy and organic chemistry. Seven major lithofacies and a basis of sedimentary microfacies classification of Niutitang shale have been divided by using X ray diffraction data, sedimentary structure, lithofacies characteristics and organic matter content. The sedimentary subfacies is divided into deep shelf facies, bathyal shelf facies and shallow shelf facies, and the geochemical condition of deep-water shelf facies is the most favorable facies for the development of organic rich shale. The average porosity of shale is 3.8% and the reservoir space of shale is mainly composed of matrix pore, of which the pore diameter is less than 50 nm. The fracture of shale is filled with calcite which made no contribution to effective reservoir space for shale gas storage and even made a certain damage for shale gas preservation. N2adsorption and SEM analysis results show that the development of shale pore is influenced by many factors. There is an increasing tendency for total pore volume if the contents of TOC, clay minerals and pyrite are increasing, but the correlation coefficient is low. It is worth noting that the correlation coefficient between pyrite and pore volume is relatively high which shows that the pyrite plays a positive role for the development of shale pore. The adsorption ability of rich organic shale is strong, which is mainly controlled by TOC. © 2015, China Coal Society. All right reserved.
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2015年第12期2884-2892,共9页
Journal of China Coal Society
基金
国家重点基础研究发展计划(973)资助项目(2013CB228000)
国家"十二五"重大专项"页岩气勘探开发关键技术"资助项目(2011ZX05018)
关键词
湘西北地区
页岩气
牛蹄塘组
沉积展布
储集特征
Chemical analysis
Digital storage
Gases
Minerals
Offshore gas fields
Petroleum reservoirs
Pyrites
Sedimentology
Shale gas
X ray diffraction
