Sedimentary characteristics of the turbidites and oil and gas accumulation in the secondary depressions in eastern China

Some concealed oil and gas pools especially secondary depressions in eastern China are now becoming the important targets of oil and gas exploration. The types of oil pools consist dominantly of lithologic and structural-lithologic oil pools of turbidity current origin. The combination of oil-generating conditions, sedimentary characteristics and oil and gas accumulation by using seismic techniques as indicated in the Denan, Niuzhuang, Lijin and Boxing secondary depressions has led us to conclude that the presence of turbidites is the main cause for the occurrence of oil and gas in continental secondary depressions. Due to the presence of undercompaction, seismic techniques may be employed as a useful tool for interpreting the oil-generating conditions of the moderate to thick-bedded dark mudstones.