Abstract: Based on the analysis of regional geology, according to drilling and logging data, seismic facies, and seismic attribute analysis of amplitude, frequency, and wave impedance, the genetic type, macro-distribution, and inner component of turbidity sandbody of Paleogene Dongying Formation of Block JZ31-A in Liaodong Bay area are analyzed. Result shows that sandbody of the Formation belongs to slump turbidite fan in front of braided delta and can be subdivided into upper fan, middle fan and lower fan subfacies. It comes from ancient river system of Fuzhou and generates from multi stagesof turbidite superposition. It is mainly controlled by valley and sloe-break zone, with less effect from dirpiric structures of the east. Combined with analysis of drilling and seismic data acquired in and around the area, pool-forming conditions of gas reservoirs are described from the perspective of basic pool-forming factors. It is shown that gas reservoirs described belong to large-scale self-generation and self-storage biogenetic gas and have good pool-forming conditions. The research is of significant theoretical and practical value for extending exploration direction and searching for similar hydrocarbon reservoirs.

Key words: Liaodong Bay, Block JZ31-A, lithologic trap, gas reservoir description, pool-forming condition