Geological characteristics and exploration of shale oil in Chang 7 Member of Triassic Yanchang Formation, Ordos Basin, NW China

作     者：FU Jinhua LI Shixiang NIU Xiaobing DENG Xiuqin ZHOU Xinping FU Jinhua;LI Shixiang;NIU Xiaobing;DENG Xiuqin;ZHOU Xinping

作者机构：National Engineering Laboratory for Exploration and Development of Low-Permeability Oil&Gas FieldsXi’an 710018China PetroChina Changqing Oilfield CompanyXi’an 710018China Exploration and Development Research Institute of PetroChina Changqing Oilfield CompanyXi’an 710018China No.8 Oil Production PlantPetroChina Changqing Oilfield CompanyXi’an 710000China China University of Petroleum(East China)Qingdao 266580China 

出 版 物：《Petroleum Exploration and Development》 (石油勘探与开发（英文版）)

年 卷 期：2020年第47卷第5期

页      面：931-945页

核心收录：

学科分类：081803[工学-地质工程] 0808[工学-电气工程] 0709[理学-地质学] 0819[工学-矿业工程] 08[工学] 0818[工学-地质资源与地质工程] 0807[工学-动力工程及工程热物理] 0708[理学-地球物理学] 0815[工学-水利工程] 0816[工学-测绘科学与技术] 0813[工学-建筑学] 0814[工学-土木工程] 

基　　金：Supported by the China National Science and Technology Major Project(2016ZX05050) the National Key Basic Research and Development Program(973 Program),China(2014CB239003) 

主　　题：Triassic Yanchang Formation Chang 7 Member shale oil main controlling factors of enrichment Qingcheng Oilfield Ordos Basin 

摘      要：A set of shale-dominated source rocks series were deposited during the heyday of lake basin development in the Member 7 of Triassic Yanchang Formation,Ordos Basin,and the thickness is about 110 m.Aimed at whether this layer can form large-scale oil enrichment of industrial value,comprehensive geological research and exploration practice have been carried out for years and obtained the following important geologic findings.Firstly,widely distributed black shale and dark mudstone with an average organic matter abundance of 13.81%and 3.74%,respectively,lay solid material foundation for the formation of shale oil.Secondly,sandy rocks sandwiched in thick organic-rich shale formations constitute an oil-richsweet spot,the average thickness of thin sandstone is 3.5 m.Thirdly,fine-grained sandstone and siltstone reservoirs have mainly small pores of 2–8μm and throats of 20–150 nm in radius,but with a large number of micro-pores and nano-throats,through fracturing,the reservoirs can provide good conductivity for the fluid in it.Fourthly,continued high-intensity hydrocarbon generation led to a pressure difference between the source rock and thin-layer reservoir of up to 8–16 MPa during geological history,driven by the high pressure,the oil charged into the reservoirs in large area,with oil saturation reaching more than 70%.Under the guidance of the above theory,in 2019,the Qingcheng Oilfield with geologic oil reserves of billion ton order was proved in the classⅠmulti-stage superimposed sandstone shale reservoir of Chang 7 Member by the Changqing Oilfield Branch through implementation of overall exploration and horizontal well volume fracturing.Two risk exploration horizontal wells were deployed for the classⅡthick layer mud shale interbedded with thin layers of silt-and fine-sandstones reservoir in the Chang 73 submember,and they were tested high yield oil flows of more than 100 tons per day,marking major breakthroughs in petroleum exploration in classⅠshale reservoirs.The new discoveries have expanded the domain of unconventional petroleum exploration.