鄂尔多斯盆地西南部庆城地区三叠系长7段—长3段层序地层特征及演化规律  

Sequence stratigraphy and evolution of Triassic Chang 7 to Chang 3 mebers in Qingcheng area,southwestern Ordos Basin

作　　者：龙盛芳 侯云超 杨超[1,2] 郭懿萱 张杰[1,2] 曾亚丽 高楠[1,2] 李尚洪[3] LONG Shengfang;HOU Yunchao;YANG Chao;GUO Yixuan;ZHANG Jie;ZENG Yai;GAO Nan;LI Shanghong(Research Institute of Exploration and Development,PetroChina Changqing Oilfield Company,Xi’an 710018,China;National Engineering Laboratory for Exploration and Development of Low-Permeability Oil and Gas Fields,Xi’an 710018,China;Oil and Gas Cooperative Development Branch,CNPC Bohai Drilling Engineering Co.,Ltd.,Tianjin 300457,China)

机构地区：[1]中国石油长庆油田公司勘探开发研究院,西安710018 [2]低渗透油气田勘探开发国家工程实验室,西安710018 [3]中国石油渤海钻探工程有限公司油气合作开发分公司,天津300457

出　　处：《岩性油气藏》2024年第1期145-156,共12页Lithologic Reservoirs

基　　金：中石油集团重大专项“鄂尔多斯盆地页岩油勘探开发理论与关键技术”(编号:2021DJ1806)资助。

摘　　要：通过井-震精细标定、凝灰岩标志层约束和速度模型正演等方法,建立了鄂尔多斯盆地西南部庆城地区三叠系长7段—长3段等时地层格架,并对地层演化特征进行了分析。研究结果表明:①庆城地区三叠系长7段—长3段湖泛泥岩具有高伽马、高声波和中—高电阻率特征,单层湖泛泥岩在横向上表现为向湖盆中心倾斜的特征,纵向上长7段—长3段均有分布,具有等时对比意义;长4+5段发育的细粒沉积是不同时期湖泛作用的叠加响应结果。②研究区长7段—长3段以湖泛泥岩为界,自下而上划分为7个等时地层单元(Pss1—Pss7),横向上彼此叠置,向湖盆中心方向进积,垂向上表现为顶积层、斜积层和底积层“三元”结构。③研究区长7段—长3段整体表现为震荡湖退背景下的前积式充填特征,其演化可分为3个阶段:早期(Pss1—Pss2),坡度相对较小,地层总体呈楔状加积—弱进积叠置样式;中期(Pss3—Pss5)随着前积斜坡推进到半深湖—深湖区,坡度变大,地层主要表现为“S”形前积结构,顶积层广泛发育三角洲前缘沉积,底积层深湖相重力流砂体发育;晚期(Pss6—Pss7)湖盆萎缩,水体变浅,斜坡高度和角度均变小,顶积层发育三角洲平原沉积,斜积层中上部主要为三角洲前缘沉积,斜积层中下部和底积层以前三角洲—半深湖相泥质沉积为主。The methods such as fine calibration of well-seismic fine calibration,constraint of tuff marker layer and forward modeling of velocity were used to establish isochronous stratigraphic framework of Chang 7 to Chang 3 mem‐bers of Triassic Yanchang Formation in Qingcheng area,southern Ordos Basin,and the stratigraphic evolution char-acteristics were analyzed.The results show that:(1)The lake flooding mudstone of Triassic Chang 7-Chang 3 mem‐bers in Qingcheng area is characterized by high gamma ray,high acoustic wave and medium to high resistivity.The individual lake flooding mudstone layer is horizontally inclined to the center of the lake basin,which can extend from the traditional members of Chang 3 to Chang 7,with isochronal correlation significance.The fine-grained sediments developed in Chang 4+5 member are the superimposed response result of lake flooding in different periods.(2)The Chang 7 to Chang 3 members in study area is bounded by lake flooding mudstone,and can be divided into seven isochronous stratigraphic units(Pss1-Pss7)from bottom to top,which are superim-posed on each other hori‐zontally and flow towards the center of the lake basin,and are vertically manifested as the“ternary”structure of top set,oblique set and bottom set.(3)In the study area,Chang 7-Chang 3 members are generally characterized by progradation filling under the background of shock lake regression,and its evolution can be divided into three stages.The first stage(Pss1-Pss2)is in the early filling stage,with relatively gentle slope,and the strata are generally in the form of wedge aggradation-weak progradation superposition.In the middle stage(Pss3-Pss5),with the progra-dation slope advancing to the semi-deep lake-deep lake area,the slope became larger,and the strata were mainly characterized by“S”type progradation structure,with delta front deposits widely developed in the top set,and gravity flow sand bodies of deep lake facies developed in the bottom set.In the late stage(Pss6-Pss7),the lake basin shrank,the water b

关 键 词：地层演化 前积斜坡 湖泛面 凝灰岩标志 正演模拟 延长组 三叠系 庆城地区 鄂尔多斯盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]