Assessment of connectivity between source rocks and strike-slip fault zone in the Fuman oilfield,Tarim Basin
The formation of hydrocarbon reservoirs in the Tarim Basin is significantly influenced by strike-slip fault zones,whose connectivity with source rocks is vital for hydrocarbon migration and accumulation.The 3D seismic data helps us to assess the connectivity of source rocks with the FⅠ17 strike-slip fault zone in block Ⅱ of the Fuman oilfield using both a discrete element model(DEM)for Riedel shear structures and a perfectly plastic medium-stress ascending function model.The findings reveal that the drag-point depth(h)of the en echelon faults of FI17 during the Late Hercynian obtained by theoretical calculation is far less than that measured by the Riedel shear DEM.This discrepancy suggests that the strike-slip faults of FⅠ17 originated from T-tensional rupturing rather than R-shear rupturing.The average depths of source rocks connected to the FI17 reach up to 9-18 km,suggesting that this fault zone acts as an immediate channel for the migration of hydrocarbons generated by the underlying source rocks of the Yurtus Formation at a burial depth of over 10 km to the overlying fault-karst(or fractured karst)traps of the Ordovician to form reservoirs.The depth(H)of source rocks connected to the FI17 zone increase from north to south.Parameters of the fault-controlled hydrocarbon reservoirs of FI17 zone,such as crude oil density,natural gas dryness coefficient,and hydrocarbon charging stages and their respective contributive degrees,are closely associated with the connectivity of FI17 zone with source rocks.Thereby,such connectivity plays a role in controlling hydrocarbon accumulation,with the controlling effects varying with the order,along-strike segmentation,activity intensity,and strike-slip fault-cut strata.The connectivity of the FI17 with source rocks changes significantly along the fault strikes,which affects the efficiency of vertical hydrocarbon transport.
connectivity with source rocksancient source rockultra-deep sequencestrike-slip faultFuman oilfieldTarim Basin
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