Characteristics of Paleogene stratigraphic and lithologic reservoirs and its exploration direction in Jizhong Depression

The Jizhong Depression is one of the hydrocarbon-rich depressions in Bohai Bay Fault Basin and has a great potential of residual hydrocarbon resources because of the low-degree exploration of stratigraphic and lithologic reservoirs.The analyses on reservoir-forming conditions and hydrocarbon distribution of the stratigraphic and lithologic reservoirs in this area suggest that this depression is characterized by three sets of regional source rocks,seven depositional systems,multi-phase structural movement and depositional break,as well as several angular unconformities.Those properties offer the favorable geological condition for forming the stratigraphic and lithologic reservoirs.Based on the origin and geometry of traps,the Paleogene stratigraphic and lithologic reservoirs in Jizhong Depression were divided into three types of lithologic reservoir,stratigraphic reservoir and compound reservoir.The stratigraphic and lithologic reservoirs concentrated in the trough belt and middle-lower part of slope and distributed around the source trough.The favorable play and exploration direction were predicted by comprehensive analysis method and proved by drilling.Four full-scale stratigraphic and lithologic reservoirs were founded.The distinct exploration benefits were obtained.