Diagenetic evolution of key minerals and its controls on reservoir quality of Upper Ordovician Wufeng-Lower Silurian Longmaxi shale of Sichuan Basin

WANG Ruyue1,2,3 HU Zongquan1 BAO Hanyong4 WU Jing5 DU Wei1 WANG Pengwei1 PENG Zeyang1 LU Ting1

(1.SINOPEC Petroleum Exploration and Production Research Institute, Beijing 100083)
(2.State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Beijing 100083)
(3.SINOPEC Key Laboratory of Shale Gas/Oil Exploration & Production, Beijing 100083)
(4.Petroleum Exploration and Development Research Institute of Jianghan Oilfield Company, SINOPEC, Wuhan, Hubei 430223)
(5.School of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao, Shandong 266500)

【Abstract】Based on core, thin section, scanning electron microscopy observations, X-ray diffraction analysis, as well as carbon and oxygen isotopes and energy spectrum analysis of carbonate rocks, the quartz, feldspar, pyrite, carbonate and clay minerals in shale of the Upper Ordovician Wufeng-Lower Silurian Longmaxi formations of Sichuan Basin were effectively characterized and classified, and the influences of their diagenetic evolution sequence on the development of shale reservoir were discussed. The results showed that good material basis and unique diagenetic sequence were the key factors for the formation of high-quality shale reservoirs.(1) Framboidal/euhedral pyrite, bio-quartz and microbial dolomite were mainly formed from the syngenetic stage to the A-substage of early diagenetic stage. They were both destructive and constructive for maintaining the original pores in shale, and the constructive supporting framework of which was critical for the formation of high-quality shale reservoir. The rigid framework formed by these early-formed minerals and terrigenous debris facilitated the maintenance of original pores and the reservoir stimulation of shale gas exploitation.(2) The co-evolution of hydrocarbon generation and diagenesis promoted the development of reservoir spaces. In the A-substage of middle diagenetic stage, the production and consumption of organic acids, the dissolution/alteration of unstable minerals(feldspar and carbonate minerals), clay mineral conversion and oil generation from kerogen were synchronic, which provided favorable space for the charging and retention of liquid hydrocarbons during the oil generation period. From the B-substage of middle diagenetic stage to the late diagenetic stage,the shale gas/organic pore generation and pressure increase of kerogen and retained hydrocarbon crackingpromoted the development of organic pores and micro-fractures, which was conducive to the enrichment and highproduction of shale gas.

【Keywords】 mineral type; diagenetic evolution sequence; shale gas; Wufeng Formation; Longmaxi Formation; Upper Ordovician; Lower Silurian; Sichuan Basin;

【DOI】

【Funds】 National Natural Science Foundation of China (41902134, 42172165) Project of SINOPEC Science & Technology Department (P20046-1)

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    References

    [1]GUO Xusheng,LI Yuping,BORJIGEN Tenger,et al.Hydrocarbon generation and storage mechanisms of deep-water shelf shales of Ordovician Wufeng formation-Silurian Longmaxi formation in Sichuan Basin,China[J].Petroleum Exploration and Development,2020,47(1):193-201.

    [2]HU Zongquan,DU Wei,LIU Zhongbao,et al.Source-reservoir coupling mechanism and application of shale gas[M].Beijing:Geological Publishing House,2018.

    [3]WANG Ruyue,HU Zongquan,DONG Li,et al.Advancement and trends of shale gas reservoir characterization and evaluation[J].Oil & Gas Geology,2021,42(1):54-65.

    [4]ZHANG Shiwan,MENG Zhiyong,GUO Zhanfeng,et al.Characteristics and major controlling factors of shale reservoirs in the Longmaxi Fm,Fuling area,Sichuan Basin[J].Natural Gas Industry,2014,34(12):16-24.

    [5]WANG Ruyue,HU Zongquan,NIE Haikuan,et al.Comparative analysis and discussion of shale reservoir characteristics in the Wufeng-Longmaxi and Niutitang formations:a case study of the well JY1 in SE Sichuan Basin and well TX1 in SE Guizhou area[J].Petroleum Geology & Experiment,2018,40(5):639-649.

    [6]WEI Limin,WANG Yan,ZHANG Tiancao,et al.Main control factors of enrichment and high production of shale gas:a case study of Wufeng-Longmaxi Formation in Southern Sichuan[J].Fault-Block Oil and Gas Field,2020,27(6):700-704.

    [7]LIU Shugen,YE Yuehao,RAN Bo,et al.Evolution and implications of shale pore structure characteristics under different preservation conditions[J].Reservoir Evaluation and Development,2020,10(5):1-11.

    [8]WANG Ruyue,NIE Haikuan,HU Zongquan,et al.Controlling effect of pressure evolution on shale gas reservoirs:a case study of the Wufeng-Longmaxi formation in the Sichuan Basin[J].Natural Gas Industry,2020,40(10):1-11.

    [9]WANG Qiao,LI Hu,LIU Ting,et al.Characterization method and main controlling factors of shale brittleness[J].Fault-Block Oil and Gas Field,2020,27(4):458-463.

    [10]ZHAO Jianhua,JIN Zhijun,JIN Zhenkui,et al.The genesis of quartz in Wufeng-Longmaxi gas shales,Sichuan Basin[J].Natural Gas Geoscience,2016,27(2):377-386.

    [11] PELTONEN C,MARCUSSEN ∅,BJ∅RLYKKE K,et al.Clay mineral diagenesis and quartz cementation in mudstones:the effects of smectite to illite reaction on rock properties[J].Marine and Petroleum Geology,2009,26(6):887-898.

    [12]LU Longfei,QIN Jianzhong,SHEN Baojian,et al.The origin of biogenic silica in siliceous shale from Wufeng-Longmaxi formation in the Middle and Upper Yangtze region and its relationship with shale gas enrichment[J].Earth Science Frontiers,2018,25(4):226-236.

    [13]XIU Hongwen.Diagenesis research and reservoir evaluation in Quan3 and Quan4 members of northern Songliao Basin[D].Daqing:Daqing Petroleum Institute,2008.

    [14]CHEN Sirui,QU Xiyu,LI Jijun,et al.Experimental study on the effect of organic acid on feldspar dissolution by thermal evolution of shale:a case from the fourth member of Shahejie Formation in Damintun Depression[J].China Sciencepaper,2019,14(1):113-120.

    [15]HUANG Keke,HUANG Sijing,TONG Hongpeng,et al.Thermodynamic calculation of feldspar dissolution and its significance on research of clastic reservoir[J].Geological Bulletin of China,2009,28(4):474-482.

    [16]LI Bo,YAN Jiaxin,LIU Xiting,et al.The organogenic dolomite model:mechanism,progress and significance[J].Journal of Palaeogeography,2010,12(6):699-710.

    [17] FANG Yihang,XU Huifang.Study of an Ordovician carbonate with alternating dolomite–calcite laminations and its implication for catalytic effects of microbes on the formation of sedimentary dolomite[J].Journal of Sedimentary Research,2018,88(6):679-695.

    [18]FU Jinhua,WANG Baoqing,SUN Liuyi,et al.Dolomitization of Ordovician Majiagou Formation in Sulige region,Ordos Basin[J].Petroleum Geology & Experiment,2011,33(3):266-273.

    [19]HOU Zhongshuai,CHEN Shiyue.Diagenesis evolution characte-ristics of shale in Upper Es4 to Lower Es3 members in Dongying Sag and its influence on the formation of reservoir[J].Petroleum Geology and Recovery Efficiency,2019,26(1):119-128.

    [20]CAO Taotao,DENG Mo,SONG Zhiguang,et al.Study on the effect of pyrite on the accumulation of shale oil and gas[J].Natural Gas Geoscience,2018,29(3):404-414.

    [21]LIU Ziyi.Shale gas significance of pyrite in Wufeng-Longmaxi formations,case study in western Hunan and Hubei[D].Beijing:China University of Geosciences (Beijing),2017.

    [22]ZHAO Xingyuan,HE Dongbo.Clay minerals and shale gas[J].Xinjiang Petroleum Geology,2012,33(6):643-647.

    [23]WANG Xingxin,XIN Guoqiang,FENG Yongcai.Clay minerals research of Songliao Basin[M].Harbin:Heilongjiang Science and Technology Press,1990.

    [24]LI Yingli,CAI Jingong.Effect of smectite illitization on shale gas occurrence in argillaceous source rocks[J].Petroleum Geology & Experiment,2014,36(3):352-358.

This Article

ISSN:1001-6112

CN:32-1151/TE

Vol 43, No. 06, Pages 996-1005

November 2021

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Article Outline

Abstract

  • l Regional geology
  • 2 Mineral types and evolution characteristics
  • 3 Effect of diagenetic evolution on reservoir development
  • 4 Conclusions
  • References