Geochemical characteristics and distribution of CO2 gas fields in Bohai Bay Basin

Eleven CO2 gas fields (pools) have been discovered in the Huanghua and Jiyang Depressions of Bohai Bay Basin, Eastern China. The analyses of natural gas geochemical data in the CO2 gas fields (pools) reveal the following: First, there is a positive correlation between CO2 content, δ13CCO2 values, and R/Ra values but a negative correlation between CO2 content and CH4 content; Second, the elevated δ13CCO2, R/Ra, and 40Ar/36Ar values show that CO2 is mantle-derived; Third, organic and inorganic alkane gases are both discovered in the CO2 gas fields of the Huanghua Depression, and the alkane gas in the Jiyang Depression is mainly oil-type. Taking the geological background of the region into consideration, the article concludes that the high geothermal field region, intersection part of faults, magmatic rock region, and high R/Ra values region are favorable abundance zones for CO2 gas fields (pools).