川东地区寒武系洗象池组构造特征及成藏模式  

Structural characteristics and hydrocarbon accumulation model of Cambrian Xixiangchi Formation in eastern Sichuan Basin

作　　者：邱玉超 李亚丁 文龙 罗冰 姚军[3] 许强 文华国[4] 谭秀成[1] QIU Yuchao;LI Yading;WEN Long;LUO Bing;YAO Jun;XU Qiang;WEN Huaguo;TAN Xiucheng(School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China;Research Institute of Exploration and Development,PetroChina Southwest Oil&Gas Field Company,Chengdu 610041,China;PetroChina Research Institute of Petroleum Exploration&Development-Northwest,Lanzhou 730020,China;Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]西南石油大学地球科学与技术学院,成都610500 [2]中国石油西南油气田公司勘探开发研究院,成都610041 [3]中国石油勘探开发研究院西北分院,兰州730020 [4]成都理工大学沉积地质研究院,成都610059

出　　处：《岩性油气藏》2024年第5期122-132,共11页Lithologic Reservoirs

基　　金：中国石油天然气股份有限公司科技重大专项“西南油气田天然气上产300亿立方米关键技术研究与应用”(编号:2016E-06)资助。

摘　　要：四川盆地东部上寒武统洗象池组是盆地内下组合油气勘探的重点领域。基于地层及沉积演化特征,利用地震、钻井岩心以及地球化学等资料,分析了川东地区上寒武统洗象池组构造特征及变形机制,从源、储、盖、运4个方面分析了其油气成藏条件,并总结了成藏模式。研究结果表明:(1)川东地区寒武系洗象池组表现为以2套滑脱变形带(中寒武统高台组膏盐岩和志留系泥岩)控制的、沿北西向传递的断褶构造,发育背冲构造、叠瓦状构造、断弯褶皱和盐底辟断弯褶皱4种构造圈闭样式;中寒武统高台组膏盐岩和中—下奥陶统泥灰岩2套盖层分别将下寒武统筇竹寺组、上奥陶统五峰组—下志留统龙马溪组2套烃源岩与洗象池组隔离。(2)研究区洗象池组具备油气成藏条件,五峰组—龙马溪组泥页岩是主要烃源岩,厚度为300~700 m,TOC值为2%~7%,生烃能力强,Ro为2.4%~4.0%,处于过成熟阶段;洗象池组沉积后期被岩溶和裂缝改造的滩相白云岩是相对优质的规模较大的储层,孔隙度大于2.1%;燕山期构造抬升和变形不仅在洗象池组形成了有效构造圈闭,还使其突破中—下奥陶统盖层与五峰组—龙马溪组对接,实现了油气的水平侧向运移。(3)研究区洗象池组为“新生古储、源储并置、侧向运移、构造圈闭”晚期天然气成藏模式;逆冲断层导致上盘褶皱的洗象池组与下盘五峰组—龙马溪组在水平面上并置,形成了源-储横向对接的构造圈闭,有效地提高了供烃和成藏的效率。The Xixiangchi Formation of the Upper Cambrian is one of the selected field for oil and gas exploration in the eastern Sichuan Basin.Based on the stratigraphic and sedimentary evolution characteristics,the structural patterns and formation mechanism of the Upper Cambrian Xixiangchi Formation in eastern Sichuan Basin were analyzed by using the data of seismic profiles,boreholes,cores and geochemistry.The hydrocarbon accumulation conditions were analyzed from the aspects of source,reservoirs,caprock and migration,and the accumulation model was summarized.The results show that:(1)The deformation of the Cambrian Xixiangchi Formation is constrained by northwestward propagated lower detachment and upper detachment in the Middle Cambrian Gaotai gypsums and Silurian mudstones,and developed four types of structural traps of back-thrust structure,double imbricated structure,fault bend fold structure and salt diapiric-related fault bend fold structure.Two caprocks attribution to both detachment layers further separate the source rocks of the Lower Cambrian Qiongzhusi Formation and Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation from the Xixiangchi Formation that raised harsh accumulation conditions.(2)The Xixiangchi Formation in the study area has the conditions for oil and gas accumulation.The shales of Wufeng Formation to Longmaxi Formation are the main hydrocarbon source rocks,with a thickness of 300-700 m,TOC values of 2%-7%and Ro values of 2.4%-4.0%.The source rocks have strong hydrocarbon generation capacity and are at an over-mature stage.The shoal dolomites transformed by karst and fractures in the later sedimentary stage of Xixiangchi Formation are relatively high-quality and large-scale reservoirs,with a porosity greater than 2.1%.The Yanshanian tectonic uplift and deformation not only formed effective structural traps in Xixiangchi Formation,but also make it break through the Middle-Lower Ordovician cap rock and connect with Wufeng Formation to Longmaxi Formation,achieving lateral migration of

关 键 词：构造圈闭 变形机制 源储侧向对接 燕山构造运动 逆冲断层 滩相白云岩 五峰组—龙马溪组 洗象池组 寒武系 川东地区 

分 类 号：TE122.1[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]