Hydrocarbon Accumulation Patterns In The Marine Paleozoic Carbonate Reservoirs In The World

There are 2512 fields in the world-wide Paleozoic marine carbonates and the discovered original proved plus probable?2P?reserves amount to 571.5×10⁸ toe?ton oil equivalent?,making up 24.1%of the total in the marine carbontes reserves,including oil124.4×10⁸ t,gas 48.1×10¹² m³ and condensate 60.9×10⁸ t.This study focuses on the integrated investigation of hydrocarbon accumulation and distribution patterns in the global Paleozoic marine carbonates.Based on the analysis of the newest database for oil and gas fields,this study attempts to document the spatio-temporal features and marco distribution patterns of petroleum resources and accumulation conditions with the application of intergrated research and spatial analysis function of Arc GIS software in the global marine Paleozoic carbonate reserviors.The accmulations of global Paleozoic marine carbonates hydrocarbons are controlled by multiple factors,including tectonic setting,tectonic framework of the basin,distribution of effective source rocks and regional evaporite seal rocks and effective source-reservoir-seal assemblages.The salient features for accumulation of hydrocarbons in Paleozoic marine carbonates include source-seal control,near-source accumulation and high-quality reservoirs.Regionally,the reserves mainly occur in the Middle East,Former Soviet Union,North America and Asia Pacific.The distribution is characterized by patterns of the?two longitududal zones and one latitudinal zone?,and the?latitudinal zone?and the?two longitudes?roughly correspond the Tethys realm and the western and eastern margins of Laurussia.Stratigraphically,the reserves are concentrated in three intervals:Permian,Carboniferous and Devonian.The 2P petroleum reserves are largely reservoired in three intervals of burial depths:2,500-3,000 m,3,500-4,000 m,and4,000-4,500 m.Passive,rift and craton basins are the most prolific basins.Though researching hydrocarbon accumulation conditions and the geological features and distribution patterns of giant marine carbonate fields in the Paleozoic,this paper analyzed and redefined the geological conditions and processes in the Paleozoic marine carbonate.Based on the analysis of?source-position?in main carbonate petroliferous basins,it revealed that the controlling effects of petroleum accumulation system?PAS?on the hydrocarbon richness in the Paleozoic marine carbonate petroliferous basins.On basis of statistical analysis of hydrocarbon distribution patterns,hydrocarbon accumulation conditions and accumulation proccesses,this study summarizes hydrocarbon accumulation and distribution patterns in the Paleozoic marine carbonates throughout the world.In terms of relative importance,the most important source intervals are Silurian,Carboniferous,and Devonian.The source rocks are dominated by mudstones and shales and bituminous shales.Dolomite and reef reservoirs are of particular significance.The Permian,Triassic and Carboniferous are the excellent seal rocks for sealing large amounts of hydrocarbon around the world.Most of hydrocarbons can be sealed by evaporite rocks,whereas tight carbonates are the common type for Paleozoic marine carbonate hydrocarbon reservoirs.The trap types vary in different regions.They are dominated by the structural type in the Middle East,complex type in the Former Soviet,structural and stratigraphic types in North America,and structural and complex types in China.