基准面升降变化控制下的湖泊三角洲前缘砂体构型耦合关系研究——以鄂尔多斯盆地东南部地区延长组长6-长8为例  

Study on the coupling relationship between base level changes and sand body configuration of lake delta front:A case study of Chang 6 to Chang 8 of the Yanchang Formation in the southeastern Ordos Basin

作　　者：徐潇 赵俊兴[1,2] 解古巍[2] 辛红刚[2] 史立川[2] 陈薪凯 彭帅杰 冯胜斌[2] 张林林 孙伟智 XU Xiao;ZHAO Junxing;XIE Guwei;XIN Honggang;SHI Lichuan;CHEN Xinkai;PENG Shuaijie;FENG Shengbin;ZHANG Linlin;SUN Weizhi(Institute of sedimentary geology,chengdu university of technology,chengdu,Sichuan 610059 china;Exploration and development research institute of petrochina changqing oilfield branch,Xi'an,shaanxi 710018,china)

机构地区：[1]成都理工大学沉积地质研究院,四川成都610059 [2]中国石油长庆油田分公司勘探开发研究院,陕西西安710018

出　　处：《矿物岩石》2024年第4期178-192,共15页Mineralogy and Petrology

基　　金：国家科技重大专项任务“鄂尔多斯盆地三叠系陆相页岩气储层特征与演化”(编号:2017ZX05036-004-006)。

摘　　要：湖泊三角洲前缘是油气勘探开发的重要方向,目前关于基准面升降变化与湖泊三角洲前缘砂体构型耦合关系的研究相对较少。本次研究综合应用高分辨率层序地层学理论,以鄂尔多斯盆地东南部地区中生界延长组长6-长8为例,综合利用野外露头、岩芯、测井等资料,其中露头6个,井163口,研究基准面升降变化对湖泊三角洲前缘的砂体构型的控制作用。结果表明:1)在湖泊三角洲前缘可识别出3类旋回结构,并进一步识别出坝上河类、席-坝类、厚泥夹薄砂类、单河道类、叠置河道类等5种基准面旋回控制下的砂体结构类型。2)基准面周期性变控制了A/S值变化,进而控制了三角洲前缘砂体结构样式:基准面上升初期多呈现叠置河道类砂体多期叠置,随着基准面升高,可容纳空间变大,单河道类砂体逐渐增多,泥岩夹层增多;在基准面上升转至下降的转折期,多表现为厚泥夹薄砂类及孤立型席-坝类砂体构型;基准面快速下降期,坝上河类砂体等逐渐显示成片出现。3)建立了基准面控制下的砂体构型模式,在垂向上呈现堆叠式、切叠式、分离式结构,侧向上呈现相切式、接触式、分离式结构。相关成果对湖泊三角洲前缘砂体中的油气勘探开发研究具有一定参考意义。The lake delta front is a critical target for oil and gas exploration and development;however,few studies have focused on the coupling relationship between base-level fluctuations and sand body config-urations in this environment.This study employs high-resolution sequence stratigraphy to explore this re-lationship,using the Chang6-Chang8 Members of the Mesozoic Yanchang Formation in the southeastern Ordos Basin as a case study.The analysis integrates data from six field outcrops,core samples,and log-ging data from 163 wells were used to analyze how base-level changes influence sand body configurations at the lake delta front.The findings reveal that:(l)Three cyclic structure types are identified at the delta front,along with five distinct sand body configurations influenced by base-level changes:river-type on the dam,sheet-dam type,thick mud-thin sand type,single-channel type,and stacked river channel type.(2)Fluctuations in the base level govern changes in the A/S ratio,which in turn shape the sand body struc-tures at the delta front.During the early stages of base level rise,multi-stage stacked river channel sand bodies form.As the base level rises further,increased accommodation space leads to the development of larger single-channel sand bodies interspersed with mudstone layers.During the transition from rising to falling base levels,sand bodies predominantly exhibit thick mud-thin sand and isolated sheet-dam configu-rations.In contrast,sharp base-level drops result in the emergence of isolated river sand bodies on the dam.(3)The study develops a model for sand body configuration under base-level control.Vertically,the configurations display stacked,cut-stacked,and separated structures,while laterally,they exhibit tan-gent,contact,and separated structures.The findings provide valuable geological insights for the explora-tion and development of oil and gas reservoirs in delta front sand bodies,offering a reference for future re-search on sand body configurations at lake delta fronts.

关 键 词：鄂尔多斯盆地 延长组 湖泊三角洲前缘 砂体构型 基准面升降 

分 类 号：TE122.1[石油与天然气工程—油气勘探]