Accumulation Process and Phase Control Factors of Large Natural Gas Reservoirs in the Oil-Prone Bohai Bay Basin,East China
Xue Yong'an
Hu Anwen
Wan Lin
Zhang Xin
Abstract：In recent years,multiple large gas reservoirs have been discovered in the oil-prone Bohai Bay Basin,among which the natural gas reserves of the Bozhong 19-6 structure exceed 100 billion cubic meters,breaking the traditional understanding that large gas reservoirs cannot be found in oil-prone basins.This article comprehensively applies oil and gas components,natural gas isotopes,fluid inclusions,and PVT analysis data to analyze the formation process and phase control factors of large-scale gas reservoirs in the Bohai Bay oil type basin.The research results indicate that large gas reservoirs have been discovered in the Bohai Bay oil-bearing basin,and have generally undergone the process of"early oil and late gas"accumulation.CO2 is influenced by both mantle and crust sources,resulting in a mixed crust mantle origin;The CO2 content affects the fluid phase state,manifested as a decrease in the critical temperature of the system as the content increases,making it more prone to gas phase.High CO2 content Paleozoic carbonate buried hills are gas reservoirs,while low CO2 content Archean buried hills are mostly condensate gas reservoirs or high volatility oil reservoirs.Therefore,the search for large condensate gas reservoirs should be considered as the exploration direction for natural gas reservoirs in oil bearing basins.
Keywords：large gas reservoiraccumulation processcarbon dioxidephase stateBohai Bay basinpetroleum geology
Publication Date：2025-02-14
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：11( 377-387 )