吐鲁番坳陷侏罗系物源体系变迁及其油气意义  

Changes of Jurassic provenance system in Turpan depression and its oil and gas exploration significance

作　　者：张晶[1,2] 郝彬 李双文[1] 魏立花[1] 刘娟娟[1] 吴青鹏[1] 徐丽[1] ZHANG Jing;HAO Bin;LI Shuangwen;WEI Lihua;LIU Juanjuan;WU Qingpeng;XU Li(PetroChina Northwest Branch,Research Institute of Petroleum Exploration and Development,Lanzhou,Gansu 730020,China;Key Laboratory of Reservoir Description,China National Petroleum Corporation,Lanzhou,Gansu 730020,China)

机构地区：[1]中国石油勘探开发研究院西北分院,甘肃兰州730020 [2]中国石油集团油藏描述重点实验室,甘肃兰州730020

出　　处：《中国矿业大学学报》2020年第4期730-741,共12页Journal of China University of Mining & Technology

基　　金：国家重大科技专项(2017ZX05001-003);中国石油天然气股份公司重大科技项目(2016B-0301-05);中国石油天然气股份公司重大科技项目(kt2018-08-03)。

摘　　要：为明确吐鲁番坳陷侏罗系物源体系特征,基于重矿物特征、砂岩碎屑组分、元素地球化学、碎屑锆石U-Pb测年等物证,从不同角度对坳陷中东部的物源方向和沉积体系进行了系统研究.认为中下侏罗统存在南、北2个物源区,坳陷不同部位、不同时期主物源体系存在明显差异.物源的变迁控制着沉积体系的演化,北部山前掩伏带为找油新领域.研究结果表明:水西沟群沉积早中期,轻、重矿物及源岩判别图解(La-Th,La/Yb-ΣREE等)显示的物源方向一致,坳陷北部碎屑锆石显示2组年龄峰值,主峰值为(297±2)Ma,次峰值为(427±4)Ma,对应于2期构造热事件,与南缘觉罗塔格山具有良好的亲缘性.受南缘长物源控制,坳陷发育北西-南东向展布的远源、长轴三角洲沉积体系,北部博格达地区为汇水沉积区,V/V+Ni,V/Cr,Ni/Co等泥岩地化指标表明古水介质为还原环境,有利于油气的形成.在水西沟晚期和三间房沉积期,重矿物和碎屑成分具有明显分区性,坳陷北部物源和沉积环境均具有近源沉积的特征,主物源来自博格达山,表明水西沟晚期是博格达山再次隆升的初始时间.In order to clarify the characteristics of Jurassic provenance system in Turpan depression,based on the evidences of heavy mineral characteristics,sand detrital components,element geochemistry,U-Pb dating of detrital zircon,the provenance direction and depositional system in the Middle East of the depression were studied systematically from different perspectives.It is considered that there are two major provenance areas in the middle and lower Jurassic,and there are obvious differences in the main provenance systems in different parts and periods of the depression.The change of provenance controls the evolution of sedimentary system,and the Northern Piedmont is a new field for oil exploration.The results show that in the early and middle period of Shuixigou group,the source directions of light and heavy minerals and source rock discrimination diagrams(such as La-Th,La/Yb-ΣREE)are consistent.The main peak value of zircon age in the northern part of the depression is(297±2)Ma,and the secondary peak value is(427±4)Ma,corresponding to the 2-stage tectonothermal events.Controlled by the long provenance in the south margin,the depression developed a NW-SE trending far source and long axis delta sedimentary system.The Bogda area in the north is a catchment sedimentary area.The geochemical indexes of mudstone such as V/V+Ni,V/Cr and Ni/Co indicate that the paleo water medium is a reducing environment,which is conducive to the formation of oil and gas.In the late Shuixigou and Sanjianfang sedimentary periods,the heavy mineral and clastic components are obviously zoned,and the provenance and sedimentary environment in the northern part of the depression are characterized by near source sedimentation.The main provenance is from Bogda mountain,indicating that the late Shuixigou is the initial time for Bogda mountain to rise again.

关 键 词：吐鲁番坳陷 博格达山 物源体系 元素地球化学 锆石U-PB定年 水西沟群 

分 类 号：TE121.3[石油与天然气工程—油气勘探]