Multilayer Superimposition Patterns of Strike-Slip Fault Zones and Their Petroleum Geological Significance in Platform Area,Tarim Basin
In recent years,with the progress of oil and gas exploration in the Tarim basin,large-scale strike-slip fault systems have been dis-covered in the Paleozoic strata of the platform area in the basin and a new type of fault-karst reservoir has been identified.Due to multiple tectonic movements in the basin,these strike-slip faults exhibit multilayer structures featured with multiple phase superimposition.Based on high-quality 3D seismic data,drilling data,and petroleum geological data,the multilayer superimposition of large-scale strike-slip faults in the basin and its controls over hydrocarbon accumulation were investigated.The research results show that the strike-slip fault zones in the platform area of the Tarim basin primarily develop five structural layers in the Paleozoic:Lower Cambrian pre-salt structural layer,Mid-dle Cambrian salt structural layer,Upper Cambrian-Middle Ordovician carbonate structural layer,Upper Ordovician-Carboniferous clas-tic structural layer,and Permian magmatite structural layer.Affected by multiple tectonic movements and strike-slip fault activities,these layers exhibit characteristics of banded spatial distribution,vertical superposition,and differential superimposition.The superimposition patterns can be broadly categorized into four types:connection,overlapping,inverse superimposition,and inverse reformation.These super-imposition patterns have significant impacts on hydrocarbon accumulation,and three types of reservoirs such as TypeⅠ(Ordovician car-bonate reservoirs),Type Ⅱ(Ordovician carbonate,Silurian clastic,and Permian magmatite reservoirs),and Type Ⅲ(Cambrian pre-salt do-lomite reservoirs)are formed.
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