Major controlling factors and enrichment rules of highly efficient gas reservoiring in the north-central part of the central inversion belt, Xihu Depression

The main controlling factors of reservoir formation and dynamic matching relationship of large gas fields in the north-central part of the central inversion belt, Xihu Depression are still unknown. Based on the systematic analysis of the key reservoir forming factors such as source rock, reservoir, transportation system and reservoir forming period, this paper establishes the dynamic reservoir forming process of "source-reservoir-Circle-Transportation" to analyze the main reservoir forming factors of the large gas field in the north of China. The results show that the source rocks of the coal measures of Baoshi Formation and Pinghu Formation in Eocene not only have a strong accumulation of gas, but also have provided sufficient oil and gas sources for the large and medium-sized natural gas reservoirs in the north-central part of the central inversion belt since the Late Miocene. The acid formation water is the key to affect the physical properties of the reservoirs. The strong compression of Longjing movement in the Late Miocene resulted in structural deformation and faults in the central inversion belt. And opening activities created conditions for the formation of traps and oil-gas transport channels. Based on the analysis of "Source-Reservoir-Circle-Transportation", we suggest that the organic coupling between the main factors of reservoir formation and hydrocarbon generation period results in the whole process of efficient gas generation of source rock and effective migration and accumulation of natural gas in Eocene coal series. The research results provide reference for the exploration of atmospheric field in the study area.