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查明下扬子古生界富有机质页岩的矿物组成特征,对页岩储层矿物组成影响页岩气储集、渗流运移和开采效果进行了研究.应用XRD、扫描电镜、低温液氮和储层敏感性实验系统分析了赣东北上震旦统皮园村组(Z_2p)、下寒武统荷塘组(∈_1h)和上二叠统乐平组(P_3l)3套海相页岩的矿物组成特征.认为3套页岩样品黏土矿物中伊利石含量均占绝对优势,高岭石含量少,表明已经历晚成岩阶段;沉积环境为碱性水介质起控制作用的深水陆棚沉积环境,这种相对还原的沉积环境为页岩气藏的形成与演化提供了良好的沉积条件;3套页岩矿物脆性指数高,整体上具有良好的储层可改造性,有利于实施页岩气的压裂改造,与北美和国内上扬子地区相比,研究区为理想的页岩气重点勘探开发层位.研究结果表明:3套页岩矿物成分均以石英占主要优势(质量分数为46.73%~64.81%),其次为黏土矿物,同时还普遍含有方解石、白云石、菱铁矿和黄铁矿等矿物;3套富有机质页岩的黏土矿物组成都以伊利石的质量分数为最高(74.58%~87.00%),其次为伊/蒙间层矿物(6.44%~20.58%).皮园村组、荷塘组、乐平组脆性指数平均值分别为67.35,77.90和48.95,易于压裂.矿物成分中石英主要影响宏孔的发育,有利于页岩气的渗流和运移,但黏土矿物控制微孔的发育并与孔隙度和渗透率呈负相关关系,有利于页岩气的保存但不利于渗流;皮园村组和荷塘组页岩储层敏感性不明显,乐平组具有中等偏弱速敏、中等偏强水敏和中等偏弱酸敏效应.理想的页岩气重点勘探开发层位次序可定为荷塘组>皮园村组>乐平组,页岩气开发工艺应根据其矿物组成的变化在不同区域分别对待.
The mineral composition characteristics of the shale organic-rich shale in the Lower Yangtze Paleozoic are ascertained and the effects of shale gas reservoir, seepage and migration and mining effect on the mineral composition of the shale reservoirs are studied.Using XRD, SEM, cryogenic liquid nitrogen and The reservoir sensitivity experiment system analyzes the mineral assemblages of the Upper Sinian Piyuan Group (Z_2p), the Lower Cambrian Hetang Formation (∈_1h) and the Upper Permian Leping Formation (P_3l) marine shale It is concluded that the illite content of clay minerals in three sets of shale samples are absolutely dominant and the content of kaolinite is small, indicating that they have undergone late diagenesis stage. The sedimentary environment is a deep-water shelf sedimentary environment in which alkaline aqueous medium plays a controlling role, The relative reduction of depositional environment provided favorable deposition conditions for the formation and evolution of shale gas reservoirs. The three sets of shale minerals have high brittleness index and good overall reservoir rebuildability, which is good for the implementation of shale gas Compared with the North America and the upper Yangtze region in China, the study area is the ideal exploration and development layer of shale gas.The results show that all the three shale mineral components are dominated by quartz (mass fraction 46.73% ~ 64.81%), followed by clay minerals, the same The calcareous minerals such as calcite, dolomite, siderite and pyrite are also commonly found in the clay minerals of the three sets of organic-rich shale. The content of illite is the highest (74.58% ~ 87.00%), followed by that of the Iraqi / (6.44% ~ 20.58%). The average brittleness index of Piyuancun, Hetang and Leping groups are 67.35, 77.90 and 48.95, respectively, which are easy to fracture.The quartz in mineral composition mainly affects the development of macropores, Which is conducive to the seepage and migration of shale gas. However, clay minerals control the micropore development and have a negative correlation with porosity and permeability, which is favorable for the preservation of shale gas but not conducive to seepage. Sensitivity of rock reservoirs is not obvious, Leping group has moderate weak sensitivity, moderate water sensitivity and moderate weak acid sensitivity effect.The ideal shale gas exploration and development stratigraphic sequence can be defined as Hetang Formation> Pianyuan Village Formation > Leping Formation, shale gas development process should be based on changes in mineral composition in different regions were treated.