南华北盆地阜凤逆冲推覆带WFD1井上古生界石炭系—二叠系储层流体包裹体特征及成藏时期研究OA

To clarify the hydrocarbon accumulation characteristics of the Carboniferous-Permian strata in the Fufeng thrust nappe structural belt of the southern North China Basin,a comprehensive analysis was conducted on the Shanxi Formation(Permian)and Taiyuan Formation(Carboniferous)reservoirs from the WFD1 well in the study area.The investigation included petrographic observation of fluid inclusions,laser Raman composition analysis,homogenization temperature measurement,and PVT(pressure-volume-temperature)simulations of hydrocarbon inclusions.The oil and gas filling times and accumulation stages in this area were determined by combining burial and thermal evolution histories.The results indicate that the Taiyuan Formation reservoir is dominated by aqueous and oil inclusions,which mainly occur in calcite-filled fractures.The fluorescence colors of the oil inclusions are blue-green and blue-white,indicating multistage hydrocarbon charging.The homogenization temperatures of the associated aqueous inclusions range from 45.5℃ to 113.3℃,with an average of 74.68℃,and their salinities range from 0.71％to 2.24％,with an average of 1.34％.The capture temperature of the late calcite vein inclusions ranges from 84.23℃ to 126.75℃,with an average of 102.47℃,and the pressure ranges from 10.62 MPa to 25.38 MPa,with an average of 17.71 MPa.In the Shanxi Formation,hydrocarbon inclusions are developed in calcite veins of sand-mudstone interbeds,and the homogenization temperature of symbiotic aqueous inclusions with oil inclusions ranges from 50.4℃ to 77.3℃,with an average of 57.8℃.At least two hydrocarbon charging stages exist in the Fufeng thrust nappe belt.During the Yanshanian period,the Carboniferous-Permian coal-measure source rocks generated oil,which migrated vertically along reverse faults to the Taiyuan Formation,resulting in oil inclusions showing blue-green fluorescence.During the Himalayan period,tectonic activation caused the crude oil to crack into condensate gas,which led to the secondary charging of the fracture system in the Shanxi and Taiyuan formations,with the oil inclusions exhibiting blue-white fluorescence.Multistage tectonic activity controls hydrocarbon accumulation in the Fufeng thrust nappe belt and exhibits reservoir-forming characteristics of"self-generation and self-storage,fault transported,and late adjustment".The hydrocarbons originated from Carboniferous-Permian coal-measure source rocks and mainly comprise light oil to wet gas.The favorable source-reservoir configuration and good preservation conditions indicate remaining unconventional hydrocarbon exploration potential under the condition of high thermal evolution of source rocks.