Diagenetic evolution and effects on reservoir development of the Dengying and Longwangmiao formations,Central Sichuan Basin,Southwestern China  

作　　者：Lei Jiang An-Ping Hu Yong-Liang Ou Da-Wei Liu Yong-Jie Hu You-Jun Tang Peng Sun Yuan-Yuan Liu Zi-Chen Wang Chun-Fang Cai 

机构地区：[1]Key Laboratory of Cenozoic Geology and Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing,100029,China [2]Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing,100029,China [3]College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing,100049,China [4]College of Resources and Environment,Yangtze University,Wuhan,Hubei,430100,China [5]PetroChina Hangzhou Research Institute of Geology,Hangzhou,Zhejiang,310023,China [6]Petroleum Exploration and Production Research Institute,SINOPEC,Beijing,100083,China [7]Sinopec International Petroleum Exploration and Production Corporation,Beijing,100029,China [8]Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu,Sichuan,610059,China

出　　处：《Petroleum Science》2023年第6期3379-3393,共15页石油科学（英文版）

基　　金：supported by grants from the National Natural Science Foundation of China(41972149,41890843).

摘　　要：The deeply buried Lower Cambrian Longwangmiao Formation and Upper Ediacaran Dengying Formation from the Sichuan Basin,China,have a total natural gas reserve up to 3×10^(12)m^(3).The complex diagenetic evolution and their impacts on the present-day reservoir quality have not been systematically elucidated,hampering the current exploration.Crucially,the integration and comparation diagenetic study on these two formations,which may be able to shed new lights on reservoir formation mechanism,are yet to be systemically evaluated.By compiling geochemistry data,including carbonate U-Pb ages and petrophysics data,coupled with new petrology,trace elements,and strontium isotope data,of various types of diagenetic carbonates,this study aims to decipher the potential links between diagenesis and reservoir development of both formations.Intriguingly,similar diagenetic sequence,which contains five distinctive dolomite phases,is established in both formations.The matrix dolomite(D1)and early dolomite cement(D2)were likely formed by reflux dolomitization,as inferred by their nearly syn-depositional U-Pb ages and elevatedδ^(18)O caused by seawater evaporation.The subsequent moderate burial dolomite cement(D3)was most plausibly the product of burial compaction as indicated by its lighterδ^(18)O and slightly younger U-Pb ages compared with D1 and D2.Whereas deep burial dolomite cements(D4 and D5)yield markedly depletedδ^(18)O,elevated ^(87)Sr/^(86)Sr,along with much younger U-Pb ages and higher precipitation temperatures,suggesting that they were likely linked to hydrothermal fluids.Despite the wide occurrence of meteoric and organic acids leaching and thermochemical sulfate reduction,they may have only played a subsidiary role on these reservoirs development.Instead,superior reservoir quality is tightly linked to tectonics as inferred by higher reservoir quality closely related to the well-developed fractures and faults filled with abundant hydrothermal minerals.Notably,good reservoirs in both formations are mainly attributed

关 键 词：Carbonate reservoir DIAGENESIS DOLOMITIZATION Meteoric water Oil charge Hydrothermal fluids Tectonic-driven fractures Deep to ultra-deep exploration 

分 类 号：P618.13[天文地球—矿床学]