坳陷湖盆重力流水道-朵叶复合体沉积特征及模式——以鄂尔多斯盆地西南部三叠系延长组长7段为例  

Sedimentary characteristics and model of gravity flow channel-lobe complex in a depression lake basin:A case study of Chang 7 Member of Triassic Yanchang Formation in southwestern Ordos Basin,NW China

作　　者：吕奇奇[1] 付金华[2,3] 罗顺社[1] 李士祥[2,3] 周新平[2,3] 蒲宇新 闫红果 LYU Qiqi;FU Jinhua;LUO Shunshe;LI Shixiang;ZHOU Xinping;PU Yuxin;YAN Hongguo(School of Geosciences,Yangtze University,Wuhan 430100,China;National Engineering Laboratory for Exploration and Development of Low Permeability Oil&Gas Fields,Xi’an 710018,China;Exploration and Development Research Institute of Changqing Oilfield Branch Company Ltd.,PetroChina,Xi’an 710018,China)

机构地区：[1]长江大学地球科学学院,武汉430100 [2]低渗透油气田勘探开发国家工程实验室,西安710018 [3]中国石油长庆油田公司勘探开发研究院,西安710200

出　　处：《石油勘探与开发》2022年第6期1143-1156,共14页Petroleum Exploration and Development

基　　金：国家自然科学基金项目(42102170);国家重点基础研究发展计划“973”项目(2014CB239003)。

摘　　要：为揭示鄂尔多斯盆地西南部三叠系延长组长7段微古地貌环境中重力流沉积体系发育特征及分布规律,在采用印模法对长7段沉积期古地貌形态进行恢复的基础上,精细刻画各微古地貌单元,并结合露头、岩心、录井和测井等资料研究重力流沉积特征及发育模式。研究结果表明:①长7段沉积期古地貌形态为东北部宽缓、西南部陡窄的不对称坳陷形态,盆内主要发育古缓坡、古斜坡和古洼地3个次级古地貌单元,再进一步细分为凸起、沟槽、坡折带、湖底平原、湖底深洼、古沟道、湖底古脊和湖底古隆8种微地貌单元;②长7段主要发育9种岩相类型、4种岩相垂向组合方式,依据岩相组成和岩相垂向组合,重力流沉积进一步细分为限制性水道、非限制性水道、天然堤、水道间、朵叶体5种沉积微相类型;③古地貌对长7段沉积物源方向、沉积微相类型和空间展布、砂体成因类型及分布具有重要控制作用。To reveal the development characteristics and distribution of gravity flow sedimentary system under micro-paleogeomorphic units of the Chang 7 Member of Triassic Yanchang Formation in the southwestern Ordos Basin,on the basis of the restoration of the paleogeomorphological form of the Chang 7 sedimentary period by the impression method,each micro paleogeomorphology unit was depicted in-depth,and the characteristics and development models of gravity flow deposits in the study area were studied in combination with outcrop,core,mud logging and log data.The results show that:(1)The paleogeomorphology in the Chang 7 sedimentary period was an asymmetrical depression,wide and gentle in the northeast and steep and narrow in the southwest.Three sub-paleogeomorphologic units were developed in the basin,including ancient gentle slope,paleo-slope and paleo-depression,and they can be further subdivided into eight micro-paleogeomorphologic units:bulge,groove,slope break belt,plain of lake bottom,deep depression of lake bottom,paleo-channel,paleo-ridge of lake bottom,and paleo-uplift of lake bottom.(2)There are 9 types of lithofacies and 4 types of lithofacies assemblages of Chang 7 Member.According to lithofacies composition and lithofacies vertical combination,the gravity flow deposit is further divided into 5 types of microfacies:restricted channel,unrestricted channel,natural levee,inter-channel,lobe.(3)Paleogeomorphology plays an important role in controlling sediment source direction,type and spatial distribution of sedimentary microfacies,genetic types and distribution of sand bodies in Chang 7 Member.

关 键 词：重力流沉积 坡折带 古地貌 水道-朵叶复合体 三叠系延长组 鄂尔多斯盆地 坳陷湖盆 

分 类 号：TE122[石油与天然气工程—油气勘探]