Ultra-deep carbonate basement reservoirs formed by polyphase fracture-related karstification in the Offshore Bohai Bay Basin, China  

作　　者：Jian Luo Hai-Yang Cao Domenico Chiarell Ru-Lin Miao Tao Ye Yun-Long Xu An-Qing Chen Xiao-Ping Luo 

机构地区：[1]State Key Laboratory of Oil&Gas Reservoir Geology and Exploration(Chengdu University of Technology),Chengdu,Sichuan,610059,China [2]Key Laboratory of Deep-time Geography and Environment Reconstruction and Applications,MNR&Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu,Sichuan,610059,China [3]Department of Earth Sciences,Royal Holloway University of London,Surrey,TW200EX,United Kingdom [4]Tianjin Branch of China National Offshore Oil Company Ltd.,Tianjin,300452,China [5]Exploration and Development Research Institute,Zhongyuan Oilfield Company,SINOPEC,Puyang,Henan,457001,China

出　　处：《Petroleum Science》2023年第4期2009-2025,共17页石油科学(英文版)

基　　金：This work was supported by the National Major Science and Technology Project of the Thirteenth Five Year Plan(No.2016zX05024-003-010);National Natural Science Foundation of China(No.42002123);the Open Fund of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Chengdu Univerisity of Technology,No.PLC2020031).

摘　　要：The Palaeozoic carbonate basement of the Offshore Bohai Bay Basin (OBBB) presents considerable potential for hydrocarbon exploration. However, the multistage tectonism and complex superimposed palaeo-karstification in the area are unclear, which leads to a lack of understanding on the formation mechanism and distribution of the deep carbonate basement reservoirs. In this study, the occurrence of a fracture-vug network and its fillings in carbonate reservoirs were investigated based on borehole cores, thin sections, and image logs from the southwestern slope of the OBBB's Bozhong Sag. Then the diagenetic fluid properties of the carbonate matrix and fillings were analysed via the data of carbon, oxygen, and strontium isotopes, and major, rare elements from coring intervals. The results revealed that fracture-related karst reservoirs have lithologic selectivity inclined toward dolomite strata. The intersecting relationships, widths, and strikes of the fractures and the regional tectonic background indicate three structural fracture families: NW-, NNE-, and NNW- trending, related to the Indosinian, middle Yanshanian, and late Yanshanian orogeny, respectively. The Indosinian NW- and end-Mesozoic NNE-trending fractures produced by compressional tectonic stress mainly contributed to the formation of the basement reservoirs. The geochemistry of the calcite veins filling these fractures suggests two main types of diagenetic fluids. The fluid of autogenic recharge related to the earlier fills is karstification diffuse flow dominated by internal runoff from rainfall in the highland setting of the Indosinian thrusting orogenic belt. The other fluid of allogenic recharge related to the later fills is the main lateral freshwater flow dominated by external runoff from the catchment in the setting of the horst-lowland within the rifting basin, induced by the Yanshanian destruction of the North China Craton. Finally, the relationship between the three fracture families and two kinds of related fluids is revealed. This allows us t

关 键 词：Carbonate basement reservoirs Buried hill Diagenetic fluid Fracture system KARSTIFICATION Bohai bay basin 

分 类 号：P618.13[天文地球—矿床学]