关键词: 天然气藏, 成藏特征, 成藏主控因素, 勘探方向, 渤中坳陷, 渤海湾盆地

Abstract: In recent years, major breakthroughs have been made in natural gas exploration in Bozhong Depression in Bohai Bay Basin, where is an important area for natural gas exploration in the future. The gas reservoir characteristics and the main controlling factors of natural gas accumulation are systematically summarized, and natural gas resource potential and exploration targets are identified in Bozhong Depression in Bohai Bay Basin by using 3D seismic, wireline logging, mud logging, and geochemical lab test data. The results show that the gas reservoirs in Bozhong Depression are mainly accumulated in the Archean metamorphic rocks buried hills, the Lower Paleozoic carbonate buried hills and the Cenozoic Paleogene glutenite reservoirs. The CO2 content of natural gas reservoirs varies greatly. The condensate gas is characterized by low CO2 content, while the dry gas is high CO2 content. The formation of large natural gas reservoir is jointly controlled by multiple factors. The late rapid maturation and high intensity gas generation of mixed source rocks are the material basis, and the multi type, large-scale and high-quality reservoir is the key to the formation of large-scale gas reservoir. The thick and over pressured mudstone caprock is the guarantee for the formation of large and medium-sized natural gas reservoir. The study indicates that buried hill and  the Cenozoic glutenite reservoir covered by thick and over pressured mudstone caprock are the favorable exploration targets in Bozhong Depression.