Research Of Fault Sealing And Fault Carrying In Southwest Depression In Dongpu

Based on the systematic analysis of faults developmental characteristics of southwest Dongpu depression,this article determined fault segmentation,fault activity history and its relationship with hydrocarbon accumulation stages,and lower limit of shale smear factor of fault sealing.Fault-controlled hydrocarbon accumulation models are then constructed.Through the seismic interpretation,four major types of fault assemblages styles were classified: Type I style displays a reverse “Y” texture constituted by main fault and its antithetic normal faults;Type ? style displays a reverse “Y” texture or “Y” texture constituted by main fault,its antithetic normal faults and its consequent faults;Type ? style are step faults constituted by main fault and its consequent faults;Type IV is the composite of the former 3 types.Oil-control faults which only cut through reservoirs of Neogene stratum and source-control faults which cut through the Neogene and Paleogene stratums are developed in the study area.Faults activity study combined with hydrocarbon accumulation stages analysis show that faults of different types and different levels have different effects on secondary hydrocarbon migration.In the main period(Dongying period)of hydrocarbon expulsion of source rocks,fault activity intensity is moderate.Oil and gas migrated through faults with strong activity during the Dongying period.After Dongying period,the slowing down or ceasing of the faults is advantageous for the preservation of oil and gas.Through the statics calculation of shale smear coefficient of dry layer,water layer,oil layer and gas layer,we determined that the faults are lateral sealing when shale smear factor CSP is more than 20,SGR is more than 0.52.The relationship between SGR and hydrocarbon height can be determined.Four fault controlled hydrocarbon accumulation models are constructed: Step faults controlled reservoir,horst faults controlled reservoir,reverse “Y” texture faults controlled reservoir,horsetail faults controlled reservoir.