Petroleum Geologic Characteristics of Southwestern Qaidam Basin and Recommendations for Further Exploration and Study

Based on analyzing the petroleum characteristics of Southwestern Qaidam Basin,in view of the existing problems in current exploration,suggestions are proposed for further exploration and study.First,seismic exploration should be launched on the piedmont overthrust nappe in the Kunlun Mountains located in Southwestern Qaidam Basin,learning the original basin boundary,finding out the distribution range,structural attitude,high focus location of downdip sedimentary rock of complex overthrust belt,and finding new exploration domains.Second,with regard to the old oilfields and oil and gas structures that have been discovered in Qigequan-Dongchaishan oil and gas accumulation zone,3D seismic data should be fully used for variable velocity mapping,ascertaining structural attitude and lateral reservoir prediction,studying new hydrocarbon reservoir assemblages probably exist in deep and shallow layers,enhancing oil recovery increasingly,ensuring high and stable yields of old oilfields,launching sequence stratigraphy study with great efforts,identifying the superimposed relation between hydrocarbon center and favorable reservoir facies and the distribution of hydrocarbon source rock,finding out the stratigraphic pinch-out zone and lithologically changing zone,ascertaining lithostratigrapic traps,and finding new hydrocarbon strata and area.Third,fine structural interpretation should be carried out:studying the effect of genetic potential of downdip of several large overthrust belts and its associated structure on oil and gas accumulation;studying the probable existence of small fault blocks and low-amplitude structure in the periphery of old oilfields,ascertaining the local strucure,lithologic traps,stratigraphic traps,and buried-hill traps that have been discovered in the great Kunbei fault.