川东盆缘带龙马溪组关键保存要素对页岩气富集的控制作用  

Controlling effect of key preservation elements on shale gas enrichment in Longmaxi Formation,eastern marginal zone of Sichuan Basin

作　　者：冯动军[1,2] 胡宗全 李双建[1] 杜伟[1,2] 师源[3] FENG Dongjun;HU Zongquan;LI Shuangjian;DU Wei;SHI Yuan(Key Laboratory of Shale oil/gas Exploration&Production SINOPEC,Beijing,100083;Petroleum Exploration and Production Research Institute SINOPEC,Beijing,100083;China University of Petroleum,Beijing,102249)

机构地区：[1]中国石化页岩油气勘探开发重点实验室,北京100083 [2]中国石油化工股份有限公司石油勘探开发研究院,北京100083 [3]中国石油大学(北京),北京102249

出　　处：《地质论评》2021年第1期144-158,共15页Geological Review

基　　金：国家重大专项任务(编号:2017ZX05036004-007);中国石化科技开发部项目(编号:P19017-4)的成果。

摘　　要：川东盆缘带是南方地区龙马溪组页岩气勘探的重点地区,已经在涪陵地区建成我国第一个页岩气大气田。研究区页岩气原始地质条件优越,但由于后期构造改造强烈,保存条件十分复杂,直接影响到页岩气的富集程度,除涪陵地区外的其他地区尚未取得产能建设的重大突破。笔者等利用钻井、野外、测井、地震及分析测试资料分析了研究区构造及演化特征、抬升剥蚀、构造样式、断裂、裂缝等对页岩气富集的影响,结合区域间接盖层、直接盖层及底板条件、地层压力、含气量、测试产量等对研究区的保存条件及判别指标进行了分析,研究认为具有正向构造背景、地层宽缓t、埋深适中及抬升剥蚀时间较晚的地区有利于页岩气的富集;断层不发育或断层封堵性好、距剥蚀区或控盆断裂越远越有利于页岩气的保存;区域性间接盖层特别是膏盐岩盖层的发育、良好的直接盖层和底板条件是页岩气能够保存的重要因素;盆内地层压力系数高,平均在1.5以上,保存条件好,页岩气富集程度高,向盆缘、盆外地区地层压力系数变低,保存条件变差,不利于页岩气的富集。综合评价川东盆缘带靠近盆内一侧为Ⅰ类保存有利区,盆内高陡背斜、盆缘斜坡及盆外残留向斜区为Ⅱ类保存有利区,盆外向斜与背斜间的区域为Ⅲ类保存有利区。Objectives:The eastern marginal zone of Sichuan Basin is a key area for shale gas exploration in the Longmaxi Formation in southern China.The first large-scale shale gas field in China has been established in the Fuling area.The original geological conditions of shale gas are superior in the study area.Due to the later strong tectonic superpositioning and reworking,the preservation conditions are very complex,which directly affect the degree of shale gas enrichment.Other than Fuling area,no major breakthrough has been achieved in productivity construction.Methods:Using drilling,field investigations,logging,seismic,and analytical test data,the effects of structural and evolutionary characteristics,uplift and denudation,structural styles,faults,and fractures on shale gas enrichment in the study area were analyzed.Combining with regional indirect and direct cap rocks and floor conditions,formation pressure,gas content,test yield,et al.,the preservation conditions and discriminant indicators of the study area were analyzed.Results:The study concluded that:the areas with a positive tectonic background,a gentle stratum,a moderate burial depth,a relatively late uplift and erosion time are conducive to the accumulation of shale gas;underdeveloped faults and good sealing property of faults,and the further away from the denuded area or basincontrolling faults,are more conducive to the preservation of shale gas;regional indirect cap rocks,especially the development of gypsum salts,good direct cap rocks and floor conditions are important factors for the preservation of shale gas;the formation pressure coefficient,over 1.5 on average,within the Sichuan Basin is high,which presents the good preservation conditions and the shale gas highly enrichment;the formation pressure coefficients gradually decrease and the preservation conditions gradually become worse from the margin of the basin to the outside,which is not conducive to the enrichment of shale gas.Conclusions:Comprehensive evaluation considers that the marginal zone clos

关 键 词：川东盆缘带 龙马溪组 页岩气 构造 保存 盖层 

分 类 号：P618.13[天文地球—矿床学]