渝西地区高含水页岩气藏特征、形成机理及地质意义  

Characteristics,formation mechanism and geological implications of high water-cut shale gas reservoirs in western Chongqing area

作　　者：吴永辉 姜振学[1,2] 吴建发 梁兴 石学文 包书景 吴伟 徐亮 唐相路[1,2] 韩云浩 WU Yonghui;JIANG Zhenxue;WU Jianfa;LIANG Xing;SHI Xuewen;BAO Shujing;WU Wei;XU Liang;TANG Xianglu;HAN Yunhao(Unconventional Petroleum Research Institute,China University of Petroleum(Beijing),Beijing 102249,China;State Key Laboratory of Petroleum Resources and Engineering//China University of Petroleum(Beijing),Beijing 102249,China;Shale Gas Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610051,China;Sichuan Key Laboratory of Shale Gas Evaluation and Exploitation,Chengdu,Sichuan 610051,China;PetroChina Zhejiang Oilfield Company,Hangzhou,Zhejiang 310023,China;Oil and Gas Survey,China Geological Survey,Beijing 100037,China)

机构地区：[1]中国石油大学(北京)非常规油气科学技术研究院 [2]油气资源与工程全国重点实验室·中国石油大学(北京) [3]中国石油西南油气田公司页岩气研究院 [4]页岩气评价与开采四川省重点实验室 [5]中国石油浙江油田公司 [6]中国地质调查局油气资源调查中心

出　　处：《天然气工业》2024年第8期58-71,共14页Natural Gas Industry

基　　金：国家自然科学基金面上项目“海相富气页岩低阻成因及其对含气性的控制机理”(编号:42072151);“深层页岩纳米孔隙介质表面性质及其流体赋存的限域效应”(编号:42372144);中国石油西南油气田公司项目“四川盆地古生界海相页岩储层发育机理及有效性评价”(编号:JS2022-80)。

摘　　要：渝西地区深层龙马溪组页岩气藏是四川盆地海相页岩气增储上产的主要领域,然而该区域局部页岩气藏高含水给深层页岩气勘探开发带来了挑战。为此,通过基础地质、地球化学、孔隙结构、连通性、断裂活动期、页岩气成藏调整期、高含水页岩的高角度方解石脉体与上下石灰岩地层锶同位素等分析,对高含水页岩气藏形成的关键因素、页岩中水的来源及路径进行了研究,并通过数值模拟明确了高含水页岩气藏的含水饱和度下限及高含水页岩气藏与低含水页岩气藏的平面边界,揭示了高含水页岩气藏的形成机理及地质意义。研究结果表明:①断穿龙马溪组地层且终止于二叠系岩溶储层的断裂是研究区局部页岩气藏高含水的关键因素。②断裂活动期与页岩气成藏调整期匹配,页岩气先散失,下二叠统栖霞组底部地层水再沿断裂进入龙马溪组页岩储层,进而形成局部高含水。③高含水页岩的含水饱和度下限为40%,断裂附近外来水供给充足时,断裂破碎带的5 km外为高含水页岩气藏与低含水页岩气藏的边界;外来水供给不充足时,可根据高含水井位向外推0.78~5.10 km,即为页岩气勘探有利区。结论认为,渝西地区二叠系岩溶储层与切穿龙马溪组且终止于二叠系地层的活动断裂是局部页岩气藏高含水的原因,该研究成果为规避渝西地区深层高含水页岩气藏、确定页岩气有利区边界及评价井井位部署提供了理论指导。The deep Longmaxi Formation shale gas reservoirs in the western Chongqing area is the main area of reserves increase and marine shale gas production in the Sichuan Basin.However,local high water cut in the shale gas reservoirs poses challenges to the exploration and development of deep shale gas in this area.After analyzing basic geology,geochemistry,pore structure,communication,fault activity period,shale gas accumulation adjustment period,high angle calcite vein of high water-cut shale and strontium isotope of overlying and underlying limestone strata,this paper studies the key factors in the formation of high water-cut shale gas reservoirs,the source and path of water in shale,the lower limit of water saturation in high water-cut shale gas reservoirs and the plane boundary between high water-cut shale gas reservoirs and low water-cut shale gas reservoirs,and clarifies the formation mechanism and geological implications of high water-cut shale gas reservoirs through numerical simulation.And the following research results are obtained.First,the fault that cuts through the Longmaxi Formation and terminates in the Permian karst reservoir is the key factor of the local high water cut.Second,the fault activity period is matched with the shale gas accumulation adjustment period.The shale gas is lost first,and then the formation water at the bottom of the Lower Permian Qixia Formation flows into the Longmaxi Formation shale along the fault to form local high water cut.Third,the lower limit of water saturation of high water-cut shale reservoir is 40%.When the external water supply near the fault is sufficient,the boundary between the high water-cut shale gas reservoir and the low water-cut shale gas reservoir is 5 km away from the fractured zone.When the external water supply is not sufficient,it can be extrapolated by 0.78–5.10 km from the high water-cut well,which is a favorable exploration area of shale gas.In conclusion,the Permian karst reservoir in the western Chongqing area and the active fault cutting through

关 键 词：四川盆地 渝西地区 龙马溪组 深层 页岩气藏 高含水饱和度 形成机理 地质意义 

分 类 号：TE122.2[石油与天然气工程—油气勘探]