Study On Hydrocarbon Migration Pathways In Liaoxi Low Uplift Of Liao Dong Bay Depression

Based on the previous study and the basic information analysis,the hydrocarbon migration system in Liaoxi Low Uplift was researched,which is the most important oil and gas gathering unit of Liao Dong Bay Depression.It also studied the hydrocarbon reservoir types and its distribution and forming process,then built the migration and-forming mode of hydrocarbon.The study region has sufficient hydrocarbon accumulating conditions of hydrocarbon source rock and two sets of reservoir-cap assemblages.Hydrocarbon is concentrated in Dongying Formation and Shehejie Formation.The main type of reservoirs is connected with fault and the fracture system is widely developed.Three basement fault and the frequently active shallow fracture constitute the most important pathways of hydrocarbon migration.The sand bodies develop well,especially for the first and the second member of Shahejie Formation and the second member of Dongying Formation.These sand bodies have good transport capacity and reservoir performance because of their poor rock-forming effect and high porosity and permeability for shallow buried.The sag-controlling faults combined with fluvial faces and delta faces reservoir body.This combination creates favorable pathways from both sides of deep sag to the low uplift for the hydrocarbon migration.The study indicates that every independent migration factor has well conducting performance,and the composite configuration of different migration factors improves the transport ability greatly.Generally,the migration system of the study area is on the bases of fault-sand-conformity-sand-fault-sand composite system.The north-east basement faults and the thick sand reservoir of Dongying formation as well as the unconformity constitute the basic Elements of this system.Reasonable transportation frame provides pathways for hydrocarbon migrating into shallow layer through vertical and lateral migration.This also contributes to the formation of many high-yield oil and gas fields form in the slope and low uplift.Through the study on JZ20-2,JZ25-1S and SZ36-1,it is concluded that the reservoirs in the study area are from Liaozhong sag mostly and have the characteristics of late period forming.Based on different structural setting and depositional condition,hydrocarbon migration and accumulation models of each oil-gas field was established.