准噶尔盆地沙湾凹陷柳树沟河沉积体系的发现及其石油地质意义  

Discovery of Liushugou river depositional system in Shawan Sag of Junggar Basin and its petroleum geological significance

作　　者：潘树新[1] 许多年[1] 唐勇[2] 曲永强[1] 王国栋[1] 董雪梅[2] 胡婷婷[2] 马永平[1] PAN Shuxin;XU Duonian;TANG Yong;QU Yongqiang;WANG Guodong;DONG Xuemei;HU Tingting;MA Yongping(PetroChina Research Institute of Petroleum Exploration&Development-Northwest,Lanzhou 730020,China;PetroChina Xinjiang Oilfield Company,Karamay 834000,Xinjiang,China)

机构地区：[1]中国石油勘探开发研究院西北分院,兰州730020 [2]中国石油新疆油田公司,新疆克拉玛依834000

出　　处：《岩性油气藏》2023年第5期26-36,共11页Lithologic Reservoirs

基　　金：中国石油科技重大专项“中西部重点盆地源—汇系统分析与沉积过程正演模拟技术研究”(编号:2021DJ0401)资助。

摘　　要：准噶尔盆地沙湾凹陷与玛湖凹陷具有相似的构造、沉积及成藏背景。基于对沙湾凹陷岩相古地理格局及源-汇系统的研究,提出了在凹陷中央发育有一个来自西北方向的远源大型沉积体系,即柳树沟河水系,并围绕该水系对沙湾凹陷的沉积演化特征及成藏条件进行了分析。研究结果表明:(1)沙湾凹陷柳树沟河水系起源于扎伊尔山,流经中拐凸起后,在沙湾凹陷中央形成了大型河流—三角洲沉积体系,其中的曲流河点砂坝、三角洲前缘水下分流河道、河口坝和席状砂等储集体是油气规模勘探的有利目标。(2)柳树沟河水系自二叠纪到侏罗纪继承性发育,先后经历了二叠纪水进、三叠纪早期水退与中—晚期水进及侏罗纪湖盆水体震荡发育的过程,形成了中、下二叠统规模烃源岩,二叠系—上三叠统大型三角洲扇体、侏罗系多期河道叠置的储集体以及晚二叠世晚期—早三叠世晚期区域性盖层,构成了纵向上多套生-储-盖优势组合;多期构造运动形成的不整合面和断裂体系构建了沙湾凹陷油气运移、调整的有利输导体系。(3)柳树沟河水系的发现改变了沙湾凹陷没有大型远源水系、仅发育近源扇三角洲的传统认识;凹陷中央及斜坡低部位是寻找石油天然气规模储层的新领域。Shawan Sag and Mahu Sag in Junggar Basin have similar tectonic,sedimentary and reservoir-forming backgrounds.Based on the study of lithofacies paleogeographic pattern and source-sink system of Shawan Sag,it was proposed that a large-scale far-source depositional system from the northwest direction was developed in the center of the sag,namely Liushugou river system,and the sedimentary evolution characteristics and hydrocarbon accumulation conditions of Shawan Sag were analyzed about this water system.The results show that:(1)Liushugou river in Shawan Sag originated from Zaire Mountain and formed a large fluvial delta depositional system in the central Shawan Sag after flowing through Zhongguai uplift.The large-scale reservoirs such as meandering river point sand bar,delta front underwater distributary channel,estuary bar and sheet sand are formed in the sag.(2)The Liushugou River developed inheritantly from Permian to Jurassic,experienced the processes of Permian transgression,early regression and mid-late transgression of Triassic,and lake water body shock development successively of Jurassic,forming scale source rocks of Middle-Lower Permian.Large delta fans of Permian-Early Triassic,multi-stage channel superimposed reservoirs of Jurassic,and regional cap rocks of late Late Permian and late Early Triassic,formed multi-sets of vertically advantageous assemblages of source-reservoir-cap rock.The unconformities and fault systems formed by multi-stage tectonic movements have constructed a favorable transport system for oil and gas migration and adjustment in Shawan Sag.(3)The discovery of Liushugou river system has changed the traditional understanding that there is no large remote river system in Shawan Sag and only near-source fan delta developed.The center of Shawan Sag and the lower part of slope are new areas for searching for large-scale oil and gas reservoirs.

关 键 词：源-汇系统 三角洲扇体 多期河道叠置 凹陷中央 斜坡低部位 远源水系 二叠纪—侏罗纪 柳树沟河沉积体系 沙湾凹陷 准噶尔盆地 

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]