The Fault Conduit And Petroleum Accumulation Within Dainan And Sanduo Formations In Deeply Subsided Area Of Gaoyou Sag

Gaoyou sag is the most rich in hydrocarbon in Subei basin,and it is in the fine exploration stage currently.The main goal in this study is to discuss the control of the fault conduits on petroleum migration and accumulation and then the distribution of residual petroleum resources.Based on the fault sealing and opening mechanism,using such methods as geological and geophysical modeling,numerical simulation and petroleum geochemistry,the fault conduits,petroleum migration pathway and petroleum-accumulating units have been discussed.Some conclusions can be drawn as follows:（1）Petroleum in deeply subsided area migrated along the Hanliu fault and Zhenwu 2 fault with fault activity rate（FAR）above 25 m/Ma.And the convex fault components were fault conduits.As well as petroleum accumulated by the sealing faults with them.（2）It was found that the lateral sealing capacity of the faults was mainly controlled by shale smear.When shale gouge rate（SGR）>0.6,the fault was lateral sealing;when it was between 0.4 and 0.6,the fault lateral sealing capacity was variable;when SGR<0.4,petroleum was able to migrate cross the fault.（3）The preferential petroleum migration pathways in Dainan Formation can be predicted by the Pathway^TMmodel,which is based on maximum-driving-force.And the key evidence was that the distribution of proved petroleum was similar to the preferential migration pathways.（4）There were two crucial periods of the petroleum migration.Petroleum,from the source rocks of Funing Formation,migrated with the active fault to the reservoir of Dainan Formation and Sanduo Formation during the deposition of Sanduo Formation.And petroleum charged into roll-over anticlines,fault trap and fault-anticline trap by short-distance lateral migration.Since the deposition of Yancheng Formation,the petroleum charged immediately into the fault trap of the first member of Dainan Formation as the overburden pressure.（5）According to the preferential migration pathways,the deeply subsided area in Gaoyou sag was re-divided into seven migration-accumulation units.The more residual petroleum resource was predicted in Huazhuang-Fumin unit and Huangjue unit.