The Structural Control Of Oil And Gas Transporting Effectiveness In Sikeshu Depression

Based on summarizing previous studies,making full use of seismic data,logging data,well logging information and oil testing materials,to research the transporting effectiveness through the theories of Structural Geology,Petroleum Geology and Reservoir Geochemistry.To analysis the transporting effectiveness of skeletal sand bodies,faults,unconformities,which could be achieved by contrasting of history and present,matching of quantitative and qualitative analysis and combination of macro and micro analysis.Based on the research of combination type of transportation system,analysising the dynamics of accumulation,to achieve the prediction of oil and gas migration.Research showed that,several skeletal sand bodies are deposited in N₁S and J in Sikeshu depression,the relatively well connectivity of skeletal sand bodies are in N₁s_1,J₂t₃ and J₁b₃stratas.They are connecting strongly in the section,distributing widely in the plane and thick on the macroscopic level,as well as penetrant on the microscopic level,are beneficial to migrating of oil and gas in long distance.Faults can obviously cut,connect and seal the skeletal sand body of Jurassic strata.Due to the difference features of the fault sealing,Aika fault can transport or accumulate oil and gas in some place.There are four kinds of unconformities between Jurassic and Cretaceous,as well as on the top of Carboniferous,oil and gas always accumulating on the border of onlap type and paralle type,or in the lonlap-truncation type.Unconformities can be divided into three layers in vertical,there are five kinds of lithologies both in top and bottom.There are eight kinds of lithology configuration mode in the top of Jurassic unconformity and Carboniferous unconformity.Oil and gas was easily transported when the conglomerate widely developed in unconformity structure.There are four types of spatial configurations,which can significantly influence the hydrocarbon migration and accumulation is fault/unconformity-sandstone-fault-sandstone mode.Oil and gas can lateral transport in skeletal sand body and unconformity,as well as transport along fault in vertical,it constitute the migration framework in space.Combina the analysis of formation pressure and fluid potential,comprehensive analysis indicate that the migration directions of Shawan strata are nearly N and NW,the migration directions of Jurassic strata are nearly N,E and NW.