To decipher the hydrocarbon distribution pattern of oil bearing basins with hydrocarbon generating in the deeper formations and then migrating along faults upwards to the shallower reservoirs

we have studied hydrocarbon migration characteristics along faults and mudstone caprock sealing conditions required for accumulating hydrocarbon.Fault characteristics at different evolution stages were studied and corresponding pressure conditions were depicted.The results showed that to seal hydrocarbons migrating along faults

different conditions were required at various stages.The hydrocarbon migration along active faults was driven by both buoyancy and formation overpressure.While the carrier system is associated cracks and induced fractures

the corresponding porosity and permeability were relatively good.In this case

the hydrocarbon migration resistance crossing through the mudstone caprock was lower.Therefore

only when faults above the caprock are disconnected with those below

can the caprock seal the migrating hydrocarbon.In contrast

the hydrocarbon migration along static faults was driven only by buoyancy

while the carrier system was of fault rock pores.In this case

the corresponding porosity is relatively poor with higher migration resistance for the hydrocarbon to break through the mudstone caprock.Therefore

to seal hydrocarbon migrating along faults

the displacement pressure of fault rock should be equal to or greater than the reservoir overpressure.