Lithofacies Paleogeography and Petroleum Exploration of Fengcheng Formation in Western Central Depression of Junggar Basin

摘要/Abstract

摘要： In order to evaluate the petroleum exploration prospects of the Fengcheng formation in the western Central depression of the Junggar basin, the lithology assemblages and sedimentary facies of the Fengcheng formation were studied by means of analyzing the trace element, core, rock thin section, paleomorphology, logging facies and seismic facies of the formation. The results show that the Fengcheng formation in the study area is fan delta-alkali lake deposition which was formed in an arid-semi-arid climate, foreland tectonic setting and geological environment with periodic changes in water salinity and water depth. From the margin to the center of the Central depression, basin-marginal fan-delta clastic rocks, outer-slope front dolomites, slope-highland volcanic rocks, low-uplift dolomitic calcareous beach-bar peperites, and the central lake-basin alkali rocks are found in sequence. According to the sedimentary characteristics, an evolution model for the fan delta-alkali lake deposition was established for the Fengcheng formation. Based on the sedimentary facies, lithofacies and petroleum exploration status, the Fengcheng formation in the study area can be divided into 5 areas such as conventional hydrocarbon area in basin-marginal ultra-denudation belt, tight hydrocarbon area in outer-slope front, shale oil/gas area in lake basin, conventional hydrocarbon area around low-uplift and conventional hydrocarbon area in highland volcanic rocks. The favorable exploration area with the depth less than 7 000 m reaches 1.2×10⁴ km², with hydrocarbon reserves of more than one billion tons, which demonstrates huge exploration potential of the total petroleum system of the Fengcheng formation in the study area.

关键词: Junggar basin, Central depression, Fengcheng formation, lithofacies paleogeography, paleoclimate, paleosalinity, alkali lake, petroleum exploration potential

Abstract: In order to evaluate the petroleum exploration prospects of the Fengcheng formation in the western Central depression of the Junggar basin, the lithology assemblages and sedimentary facies of the Fengcheng formation were studied by means of analyzing the trace element, core, rock thin section, paleomorphology, logging facies and seismic facies of the formation. The results show that the Fengcheng formation in the study area is fan delta-alkali lake deposition which was formed in an arid-semi-arid climate, foreland tectonic setting and geological environment with periodic changes in water salinity and water depth. From the margin to the center of the Central depression, basin-marginal fan-delta clastic rocks, outer-slope front dolomites, slope-highland volcanic rocks, low-uplift dolomitic calcareous beach-bar peperites, and the central lake-basin alkali rocks are found in sequence. According to the sedimentary characteristics, an evolution model for the fan delta-alkali lake deposition was established for the Fengcheng formation. Based on the sedimentary facies, lithofacies and petroleum exploration status, the Fengcheng formation in the study area can be divided into 5 areas such as conventional hydrocarbon area in basin-marginal ultra-denudation belt, tight hydrocarbon area in outer-slope front, shale oil/gas area in lake basin, conventional hydrocarbon area around low-uplift and conventional hydrocarbon area in highland volcanic rocks. The favorable exploration area with the depth less than 7 000 m reaches 1.2×10⁴ km², with hydrocarbon reserves of more than one billion tons, which demonstrates huge exploration potential of the total petroleum system of the Fengcheng formation in the study area.

Key words: Junggar basin, Central depression, Fengcheng formation, lithofacies paleogeography, paleoclimate, paleosalinity, alkali lake, petroleum exploration potential

HE Haiqing, TANG Yong, ZOU Zhiwen, GUO Huajun, XU Yang, LI Yazhe. Lithofacies Paleogeography and Petroleum Exploration of Fengcheng Formation in Western Central Depression of Junggar Basin[J]. 新疆石油地质, 2022, 43(zk(English)): 17-31.

参考文献

[1] QIN Zhijun,CHEN Lihua,LI Yuwen,et al.Paleo-sedimentary setting of the Lower Permian Fengcheng alkali lake in Mahu sag,Junggar basin[J]. Xinjiang Petroleum Geology,2016,37(1):1-6.
[2] CAO Jian,LEI Dewen,LI Yuwen,et al.Ancient high-quality alkaline lacustrine source rocks discovered in the Lower Permian Fengcheng formation,Junggar basin[J]. Acta Petrolei Sinica,2015,36(7):781-790.
[3] ZHANG Zhijie,YUAN Xuanjun,WANG Mengshi,et al.Alkaline-lacustrine deposition and paleoenvironmental evolution in Permian Fengcheng formation at the Mahu sag,Junggar basin,NW China[J]. Petroleum Exploration and Development,2018,45(6):972-984.
[4] LI Wei,ZHANG Yuanyuan,NI Minjie,et al.Genesis of alkaline lacustrine deposits in the Lower Permian Fengcheng formation of the Mahu sag,northwestern Junggar basin:insights from a comparison with the worldwide alkaline lacustrine deposits[J]. Acta Geologica Sinica,2020,94(6):1 839-1 852.
[5] WANG Libao,HOU Gangfu,BIAN Baoli,et al.The role of modern alkaline lakes in explaining the sedimentary environment of the Fengcheng formation,Mahu depression[J]. Acta Sedimentologica Sinica,2020,38(5):911-922.
[6] ZHI Dongming,TANG Yong,ZHENG Menglin,et al.Geological characteristics and accumulation controlling factors of shale reservoirs in Fengcheng formation,Mahu sag,Junggar basin[J]. China Petroleum Exploration,2019,24(5):615-623.
[7] CHEN Lei,YANG Yiting,WANG Fei,et al.Exploration history and enlightenment in Junggar basin[J]. Xinjiang Petroleum Geology,2020,41(5):505-518.
[8] XUE Jingjing,SUN Jing,ZHU Xiaomin,et al.Characteristics andformation mechanism for dolomite reservoir of Permian Fengchengformation in Junggar basin[J]. Geoscience,2012,26(4):755-761.
[9] ZHU Shifa,ZHU Xiaomin,TAO Wenfang,et al.Origin of dolomitic reservoir rock in the Permian Fengcheng formation in Wu-Xia area of the Junggar basin[J]. Geological Journal of China Universities,2013,19(1):38-45.
[10] YU Kuanhong,CAO Yingchang,QIU Longwei,et al.Brine evolution of ancient lake and mechanism of carbonate minerals during the sedimentation of Early Permian Fengcheng formation in Mahu depression,Junggar basin,China[J]. Natural Gas Geoscience,2016,27(7):1 248-1 263.
[11] TANG Yong,ZHENG Menglin,WANG Xiatian,et al.Sedimentary paleoenvironment of source rocks of Fengcheng formation in Mahu sag,Junggar basin[J]. Natural Gas Geoscience,2022,33(5):677-692.
[12] YOU Xingdi.Discuss on the Lower Permian Fengcheng formation in the northwest margin of Junggar basin[J]. Xinjiang Petroleum Geology,1986,7(1):47-52.
[13] LU Xinchuan,SUN Dong,XIA Weimin,et al.The dolomitization of Permian Fengcheng formation and its effect on reservoir in northwestern Junggar basin[J]. Natural Gas Geoscience,2015,26(2):52-61.
[14] FENG Youliang,ZHANG Yijie,WANG Ruiju,et al.Dolomites genesis and hydrocarbon enrichment of the Fengcheng formation in the northwestern margin of Junggar basin[J]. Petroleum Exploration and Development,2011,38(6):685-692.
[15] JIANG Yiqin,WEN Huaguo,QI Liqi,et al.Salt minerals and their genesis of the Permian Fengcheng formation in Urho area,Junggar basin[J]. Journal of Mineralogy and Petrology,2012,32(2):105-114.
[16] PAN Xiaotian.Forming mechanism of Fengcheng formation of lacusteine hydrothermal dolomite in the Junggar basin in northwestern margin[D]. Chengdu:Chengdu University of Technology,2013.
[17] WANG Qiyu,MOU Chuanlong,CHEN Xiaowei,et al.Palaeogeographic characteristics and basic geological conditions of petroleum of the Carboniferous in Junggar basin and its adjacent areas[J]. Journal of Palaeogeography,2014,16(5):655-671.
[18] ZHOU Jingao,XI Shengli,DENG Hongying,et al.Tectonic-lithofacies paleogeographic characteristics of Cambrian-Ordovician deep marine carbonate rocks in the Ordos basin[J]. Natural Gas Industry,2020,40(2):41-53.
[19] MA Hui,SU Zhongtang,LIANG Ru,et al.New evidence for the genesis of Qixia formation dolomites in the western Sichuan basin:geochemical characteristics of rare earth elements[J]. Natural Gas Industry,2021,41(12): 49-59.
[20] LIU Junying,CAO Liming,LI Zhaolin,et al.Elemental geochemistry[M]. Beijing:Science Press,1984:422-428.
[21] MCCULLOCH M,CAPPOM,AUMEND J,et al.Tracing the life history of individual barramundi using laser ablation MC-ICP-MS Sr-isotopic and Sr/Ba ratios in otoliths[J]. Marine & Freshwater Research,2005,56(5):637-644.
[22] LEVENTHAL J S.Relationship between inferred redox potential of the depositional environment and geochemistry of the Upper Pennsylvanian(Missourian) stark shale member of the Dennis limestone,Wabaunsee County,Kansas,USA[J]. Chemical Geology,1992,99(1/2/3):65-82.
[23] XIE Jirong,LI Ya,YANG Yueming,et al.Main controlling factors and natural gas exploration potential of Permian scale volcanoclastic reservoirs in the western Sichuan basin[J]. Natural Gas Industry,2021,41(3):48-57.
[24] HUANG Yun,LIANG Shuyi,JIA Chunming,et al.Identification and oil and gas exploration practices of reworked residual paleovolcanic edifice in the Junggar basin[J]. Natural Gas Industry,2020,40(3):30-37.
[25] XIA Maolong,WEN Long,LI Ya,et al.Permian volcanic eruption cycle,environment and model in the Jianyang area of the Sichuan basin[J]. Natural Gas Industry,2020,40(9):11-22.
[26] ZHU Shifa,ZHU Xiaomin,LIU Jishan,et al.Genesis and hydrocarbon significance of vesicular ignimbrite:a case study from Fengcheng formation,Wu-Xia area,Junggar basin,NW China[J]. Petroleum Exploration and Development,2012,39(2):162-171.
[27] YANG Zhifeng,TANG Yong,GUO Xuguang,et al.Occurrence states and potential influencing factors of shale oil in the Permian Fengcheng formation of Mahu sag,Junggar basin[J]. Petroleum Geology & Experiment,2021,43(5):784-796.
[28] LIU Yinghui.Origin of dolomitic tuff in Permian Fengcheng formation in Wu-Xia area of Junggar basin[J]. Journal of Jilin University (Earth Science Edition),2022,52(1):80-93.
[29] ZHI Dongming,TANG Yong,HE Wenjun,et al.Orderly coexistence and accumulation models of conventional and unconventional hydrocarbons in Lower Permian Fengcheng formation,Mahu sag,Junggar basin[J]. Petroleum Exploration and Development,2021,48(1):38-51.
[30] HE Wenjun,QIAN Yongxin,ZHAO Yi,et al.Exploration implications of total petroleum system in Fengcheng formation,Mahu sag,Junggar basin[J]. Xinjiang Petroleum Geology,2021,42(6):641-655.