川东红星地区中上二叠统页岩气勘探成果及方向展望  

Exploration achievements and prospects for shale gas of Middle-Upper Permian in Hongxing area,eastern Sichuan Basin

作　　者：包汉勇[1] 赵帅[1] 张莉[1] 刘皓天[1] BAO Hanyong;ZHAO Shuai;ZHANG Li;LIU Haotian(Research Institute of Exploration and Development,Sinopec Jianghan Oilfield Company,Wuhan 430223,China)

机构地区：[1]中国石油化工股份有限公司江汉油田分公司勘探开发研究院,武汉430223

出　　处：《岩性油气藏》2024年第4期12-24,共13页Lithologic Reservoirs

基　　金：中国石化股份公司科研项目“川东地区重点层系页岩气成藏条件与评价技术研究”(编号:P23077)资助。

摘　　要：基于构造、岩心、测井等资料,采用电镜扫描、低温N_(2)吸附实验、高压压汞实验、盆地模拟等手段,系统分析了川东红星地区中上二叠统页岩的沉积演化、储层特征及页岩气富集模式,明确了勘探有利区,总结了勘探成果及意义。研究结果表明:(1)红星地区中上二叠统的沉积演化表现为:栖霞组—茅口组三段为开阔台地相;茅四段底部为台地-陆棚相,相带变化快,茅四段顶部为斜坡-陆棚相,地层被剥蚀、南厚北薄;吴家坪组一段(吴一段)底部为海陆过渡滨岸沼泽-潟湖相,吴一段顶部为台地-斜坡-陆棚相,斜坡-陆棚相带分布范围小、相变快;吴二段为斜坡-陆棚相沉积,从早至晚依次受控于古气候、火山活动和古气候、火山活动,沉积中—晚期古生产力较高,TOC均值大于8.00%。(2)研究区茅四段及吴二段陆棚相区发育2套优质页岩,具有“高有机碳-高灰质”的特征,富有机质页岩厚度分别为19 m和25 m,孔隙类型以有机孔为主,结构以微孔和介孔为主;富碳凝灰岩薄夹层混合质页岩岩相、高碳凝灰岩薄夹层硅质页岩为优质岩相,孔隙度分别为6.27%和6.43%,TOC值分别为10.11%和9.35%,含气饱和度分别为92.59%和91.81%,脆性指数分别为55.24%和61.19%,是地质和工程的双“甜点”段。(3)研究区二叠系广泛发育的层状藻为主要有机质来源;在侏罗纪主排烃期,其构造稳定、二叠系烃源岩排烃较少,中侏罗纪—早白垩纪早期为主生气期,构造活动较弱,页岩气的保存条件好,现今已完成生气过程,处于成熟—过成熟阶段,Ro值约2.1%,勘探潜力巨大。(4)建南、龙驹坝、三星区块为有利勘探区,其中建南区块潜力最大;茅四段(3)小层及吴二段(3)小层为优质层系的靶窗层段。Based on tectonic,core and logging data,a systematic analysis was conducted on the sedimentary evolution,reservoir characteristics and shale gas enrichment models of Middle-Upper Permian shale in Hong-xing area of eastern Sichuan Basin by means of electron microscope scanning,low-temperature N_(2) adsorption experiments,high-pressure mercury pressure experiments and basin simulation,the favorable exploration areas were identified,the exploration results and significance were summarized.The results show that:(1)The sedimentary evolution of Middle-Upper Permian in Hongxing area is characterized by open platform facies in Qixia-Maokou Formation;platform-shelf facies at the bottom of the fourth member of Maokou Formation,with fast facies change,while slope-shelf facies at the top of the fourth member of Maokou Formation,with strata denuded,thicker in the south and thinner in the north;marine-terrestrial transitional coastal swamp-lagoon facies at the bottom of the first member of WujiapingFormation,while platform-slope-shelf facies at the top of the first member of WujiapingFormation,with small distribution and fast facies change;slope-shelf facies in the second member of WujiapingFormation,which was controlled by paleoclimate,volcanic activity,paleoclimate,and volcanic acti-vity from early to late,with high paleoproductivity during the middle to late sedimentary periods and average TOC greater than 8.00%.(2)Two sets of high-quality shales were developed in the shelf facies areas in the fourth member of Maokou Formation and the second member of Wujiaping Formation,with high organic carbon and high calcite content.Their thicknesses of organic-rich shales are 19 m and 25 m,respectively.The pores are dominated by organic pores,and the structures are mainly micropores and mesopores.The thinly interbedded mixed shale phases of carbon-rich tuff and the thinly interbedded siliceous shale phases of high carbon tuff are high-quality phases,with porosity of 6.27%and 6.43%,TOC of 10.11%and 9.35%,gas saturation 92.59%and 91.81%,

关 键 词：深层页岩气 沉积演化 有机孔 斜坡-陆棚 “高有机碳-高灰质”页岩 吴家坪组 茅口组 中上二叠统 川东红星地区 

分 类 号：TE121.3[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]