四川盆地梓潼-平昌地区雷口坡组四段成藏地质条件差异  

Reservoir-forming difference in Leikoupo 4 Member,Zitong-Pingchang area,Sichuan Basin

作　　者：刘辉[1] 刘鑫[1] 吴雪峰[1] 战薇芸[1] 叶茂[1] 李龙[1] 谢正龙[1] 陈尘[1] 张竞月 张歆妍 Liu Hui;Liu Xin;Wu Xuefeng;Zhan Weiyun;Ye Mao;Li Long;Xie Zhenglong;Chen Chen;Zhang Jingyue;Zhang Xinyan(Exploration and Development Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sich­uan 610041,China)

机构地区：[1]中国石油西南油气田公司勘探开发研究院

出　　处：《天然气勘探与开发》2022年第1期22-32,共11页Natural Gas Exploration and Development

基　　金：中国石油西南油气田公司科学研究与技术项目“四川盆地海相碳酸盐岩储量升级评价研究及应用”(编号:20210311-25)。

摘　　要：钻探证实四川盆地梓潼—平昌地区中三叠统雷口坡组四段3亚段在区内的东、西部成藏地质条件存在较大差异。因此,有必要开展差异性的对比分析,为下步勘探提供参考。为此,借助分析化验、钻探资料和地震预测手段,通过剖析雷四段的沉积演化及特征,研究受多种因素控制下的储层分布特征、烃源条件,结合构造演化分析成果,由此探讨该区东、西部地区雷口坡组四段3亚段成藏模式的差异。研究结果表明:①目标区域东部地区优势沉积相为内颗(鲕)粒滩微相,其次为云坪微相,西部地区优势沉积相为云坪沉积微相。②受颗粒滩体、岩溶和裂缝的发育程度控制,东部地区储层发育在a小层,为滩相叠加岩溶型云岩储层和角砾云岩储层,储集条件好;西部地区储层主要发育在b小层细—粉晶云岩中,储集条件变差。③西部地区烃源来自于须家河组,雷口坡组四段3亚段储层与烃源通过不整合面、小型断层,形成“上生下储”“旁生侧储”的源储匹配关系;东部地区烃源来自于须家河组和二叠系,雷口坡组四段3亚段储层与烃源通过大型断裂、不整合面沟通,形成“上生下储”“下生上储”和“旁生侧储”的3种源储匹配关系。④在大型斜坡和地层尖灭的背景下,推测西部地区发育岩性、构造岩性圈闭气藏。此外,东部地区在局部构造高部位、滩体残存区还发育构造—地层、构造圈闭气藏,气水关系复杂。结论认为,东部地区成藏地质条件优于西部,东部地区是深化挖潜的有利区,西部地区适当开展预探工作,是寻找突破的区域。Drilling practice in T2l43 submember,Zitong-Pingchang area,Sichuan Basin,shows big difference in reservoir-forming geological conditions between eastern and western area.So,it’s necessary to implement a comparative analysis on the difference to guide the next exploration.Through experimental analysis and drilling data,and seismic prediction to examine depositional evolution and feature in the Leikoupo 4 Member(T2l4),the reservoir distribution,source condition,and structural evolution affected by multiple factors were studied to make clear the reservoir-forming difference of T2l43 in both eastern and western Zitong-Pingchang area.Results show that(1)the predominant sedimentary facies are intra-grain bank(intra-oolitic beach)and dolomitic flat in the east whereas dolomitic flat in the west;(2)dominated by the development of grain bank,karst,and fracture,reservoirs are composed of beach-facies and karstic dolomite and brecciated dolomite with good petrophysical property in layer a in the east whereas fine to crystal powder dolomite with poor petrophysical property in layer b in the west;(3)in the west,the source rock of Xujiahe Formation and the T2l43 reservoirs form two sets of assembly by means of unconformity and small faults,containing“top source and bottom reservoir”as well as“one side source and the other reservoir”.In the east,the source rock of both Xujiahe Formation and Permian and the T2l43 reservoirs generate three sets of assembly also by means of unconformity and small faults,such as“top source and bottom reservoir”,“bottom source and top reservoir”,and“one side source and the other reservoir”;and(4)in the west,not only lithologic but also structural-lithologic reservoirs may occur against the background of large slope and pinchout.Whereas in the east,both structural-stratigraphic and structural reservoirs with complicated gas-water correlation,are developed at structural high or residual beach.In conclusion,the east area,which is superior to the west one in reservoir-forming condi

关 键 词：四川盆地 梓潼—平昌地区 中三叠世 雷口坡组四段 成藏地质条件 差异性分析 成藏模式 

分 类 号：P618.13[天文地球—矿床学]