鄂尔多斯盆地东南部三叠系长7油层组深水沉积特征及演化规律  

Characteristics of deep-water deposits and evolution law of Triassic Chang 7 reservoir in southeastern Ordos Basin

作　　者：尹虎 屈红军[1] 孙晓晗[1] 杨博 张磊岗[1] 朱荣幸 YIN Hu;QU Hongjun;SUN Xiaohan;YANG Bo;ZHANG Leigang;ZHU Rongxing(State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi’an 710069,China;Fuxian Oil Production Plant,Yanchang Oilfield Co.,Ltd.,Fuxian 727500,Shaanxi,China)

机构地区：[1]西北大学地质学系,大陆动力学国家重点实验室,西安710069 [2]延长油田股份有限公司富县采油厂,陕西富县727500

出　　处：《岩性油气藏》2024年第5期145-155,共11页Lithologic Reservoirs

基　　金：国家自然科学基金“华北南缘与西缘早古生代等深流沉积特征类比及地质意义”(编号:41172101);国家自然科学基金重大项目专题“致密气储层地质评价方法”(编号:41390451)联合资助。

摘　　要：以沉积学理论为指导,利用野外露头、钻井岩心、测井等资料,对鄂尔多斯盆地东南部三叠系长7油层组深水沉积特征包括相标志、沉积微相类型等进行了研究,并揭示了其沉积演化规律。研究结果表明:(1)鄂尔多斯盆地东南部三叠系长7油层组深水沉积的相标志包括:岩石中常见水平层理、鲍马序列、槽模沟模、滑动与滑塌构造、撕裂屑、泥包砾等沉积构造,含有深水双壳类和鱼类动物化石,粒度概率曲线中悬浮总体含量大且分选差,测井曲线上可见锯齿状、齿化箱形-钟形-指形、泥岩基线等特征。(2)研究区长7物源主要来自东北和南部2个方向,发育深湖—半深湖、湖底扇、浅湖沉积,湖底扇包括浊流和砂质碎屑流2种重力流类型,可进一步划分为重力流主水道、溢流沉积、重力流分支水道、分支水道间、朵叶体等微相。湖底扇主水道主要为砂质碎屑流沉积,分支水道和朵叶体主要为浊流沉积。(3)研究区长7沉积期,中南部主体发育深湖—半深湖、湖底扇沉积,东北部发育浅湖沉积;其中,东北方向发育4个湖底扇体,南部发育2个湖底扇体,半深湖/浅湖界线呈北西向延伸于延安—甘泉一带。长7^(3)亚段沉积期,深湖—半深湖范围最大,仅局部发育湖底扇;长7^(2)、长7^(1)亚段沉积期,湖底扇逐步增多,深湖—半深湖范围有所缩小,整体呈深湖—半深湖与湖底扇交互沉积态势。Guided by the theory of sedimentology,the data of outcrops,drilling cores and logging were used to study the characteristics of deep-water deposits,including facies markers and sedimentary microfacies types,of Triassic Chang 7 reservoir in southeastern Ordos Basin,and the evolution law was revealed.The results show that:(1)Facies markers of deep-water deposits of Triassic Chang 7 reservoir in southeastern Ordos Basin include sedimentary structures such as horizontal bedding,Bouma sequence,trough mode,sliding and slump structure,tearing debris,mud-clad gravel,containing deep-water bivalves and fish fossils.The total suspended content in the grain size probability curve is large and the sorting is poor,and the features of zigzag,teethed box-bell-finger shaped and mudstone baseline can be seen on the logging curve.(2)The provenance of Chang 7 reservoir in the study area mainly comes from the northeast and south,with the development of deep to semi-deep lake,sublacustrine fan and shallow lake,and shallow lake sediment.The sublacustrine fan includes two types of gravity flow:turbidity flow and sandy debris flow.It can be further divided into microfacies such as gravity flow main channels,overflow deposits,gravity flow branch channels,inter branch channels,and lobes.The main channels of the sublacustrine fan mainly developed sandy debris flow deposits,while the branch channels and lobes are mainly developed turbidite deposits.(3)The sedimentary evolution law of Chang 7 reservoir in the study area is as follows:deep to semi-deep lake and sublacustrine fan deposits were developed in the central and southern parts of the study area,and shallow lake deposits were developed in the northeastern part.Four sublacustrine fans from the northeast direction were developed in the study area and two sublacustrine fans from the south were developed.The boundary between semi-deep lake and shallow lake extends along Yan’an-Ganquan belt from northwest dire-ction.During the sedimentary period of Chang 7^(3),the range of deep to semi-de

关 键 词：相标志 深水沉积 浊流 砂质碎屑流 湖底扇 长7 三叠系 鄂尔多斯盆地东南部 

分 类 号：TE121.3[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]