四川盆地南部中二叠统茅口组岩溶古地貌恢复及特征  

Restoration and characteristics of karst paleogeomorphology of Middle Permian Maokou Formation in southern Sichuan Basin

作　　者：张坦 贾梦瑶 孙雅雄 丁文龙[4] 石司宇 范昕禹 姚威 ZHANG Tan;JIA Mengyao;SUN Yaxiong;DINGWenlong;SHI Siyu;FAN Xinyu;YAOWei(Wuxi Research Institute of Petroleum Geology,Sinopec,Wuxi 214126,Jiangsu,China;Jiangsu Oilfield Company,Sinopec,Yangzhou 225009,Jiangsu,China;College of Geoscience,Northeast Petroleum University,Daqing 163318,Heilongjiang,China;School of Energy Resources,China University of Geosciences(Beijing),Beijing 100083,China;Sinopec Exploration Company,Chengdu 610041,China)

机构地区：[1]中国石化勘探开发研究院无锡石油地质研究所,江苏无锡214126 [2]中国石化江苏油田分公司,江苏扬州225009 [3]东北石油大学地球科学学院,黑龙江大庆163318 [4]中国地质大学(北京)能源学院,北京100083 [5]中国石化勘探分公司,成都610041

出　　处：《岩性油气藏》2024年第1期111-120,共10页Lithologic Reservoirs

基　　金：中国石化勘探分公司项目“川南地区东吴期古构造特征研究”(编号:35450003-17-ZC0607-0016);江苏省卓越博士后计划联合资助。

摘　　要：岩溶古地貌是含油气盆地沉积微相类型、分布范围及储层发育的主控因素,恢复岩溶古地貌对指导油气勘探至关重要。基于钻井、测井及地震等资料,采用沉积速率法和地层厚度对比法对四川盆地南部地区中二叠统茅口组顶部不整合界面的剥蚀厚度进行了精确计算,并根据剥蚀厚度的地区差异及古地貌指示,对岩溶古地貌单元进行了进一步划分。研究结果表明:①四川盆地南部中二叠统茅口组顶部主要发育平行不整合,仅在局部地区形成角度不整合。早中二叠世,上扬子地台内部沉积稳定,构造运动较弱,沉积速率法与地层厚度对比法相对更适用于研究区的岩溶古地貌恢复。②研究区中二叠统茅口组顶部剥蚀厚度为0~120m,其中北部剥蚀最强烈,如LG1井区、W4井区代表了岩溶古地貌地势的最高位置,向东南方向剥蚀强度逐渐减弱,地势逐渐降低;剥蚀最薄弱地区位于LS1井东北部,代表了岩溶古地貌地势的最低位置,整体呈现北部高,南部低,东北部最低的地貌格局。③研究区茅口组古地貌特征控制了岩溶作用的发育强度,可划分为岩溶高地、岩溶斜坡、岩溶盆地等3个二级岩溶古地貌单元以及溶峰盆地、溶丘洼地、丘丛谷地、丘丛洼地、丘丛沟谷、峰林平原、残丘平原等7个三级古地貌单元,其中岩溶斜坡易形成良好的储集空间,为油气圈闭的形成奠定了良好的基础,是下一步有利勘探方向。Karst paleogeomorphology is one of the main controlling factors of sedimentary microfacies type,distri-bution range and reservoir development in petroliferous basins.It is very important to restore karst palaeogeomor‐phology to guide oil and gas exploration.Based on a large number of drilling,logging and seismic data,the denuda-tion thickness of the unconformity interface at the top of Middle Permian Maokou Formation in southern Sichuan Basin was calculated by using sedimentation rate method and stratum thickness comparison method,and the karst paleogeomorphology units were divided according to the regional differences of the denudation thickness and paleogeomorphic indicators.The results show that:(1)The top of Middle Permian Maokou Formation in southern Sichuan Basin mainly developed parallel unconformities,and only formed angular unconformity in local areas.Under the background of stable sedimentation and weak tectonic movement in Upper Yangtze platform during Early and Middle Permian,sedimentation rate method and stratum thickness comparison method are relatively more suitable for the restoration of karst palaeogeomorphology in the study area.(2)The denudation thickness of the top of Middle Permian Maokou Formation in the study area changes from 0 to 120 m.The strongest denuda‐tion areas are near the wells LG1 and W4 in the north,which represent the highest position of the karst ancient landform.The denudation intensity gradually weakens towards the southeast,and the terrain gradually decreases.The weakest denudation areas are located in the northeast of well LS1,which represents the lowest position of the karst ancient landform.The overall landscape pattern is“high in the north,low in the south and lowest in the northeast”.(3)The paleogeomorphology of Maokou Formation in the study area controls the intensity of karst development,which can be divided into three secondary karst paleogeomorphic units,namely,karst highlands,karst slopes and karst basins,and seven tertiary paleogeomorphic units,including

关 键 词：沉积速率法 地层厚度对比法 古地貌恢复 岩溶储集体 茅口组 中二叠统 四川盆地南部 

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]