Ecological features of sulphate-reducing bacteria in a CO2 flooding gathering environment

CO2 flooding can improve the oil recovery factor more effectively compared with conventional water flooding; however, a problem occurs when H2S is produced more rapidly due to the influence of sulphate-reducing bacteria (SRB). On the basis of the ecological features of sulphate-reducing bacteria (SRB) and the effects of CO2 flooding on the properties of the production fluid, we analysed the ecological features of sulphate-reducing bacteria in a CO2 flooding gathering environment through research on the content change of SRB, H2S, and the full components of the associated gas in the process of “the wellhead→ the metering station→ the transfer station→ the joint station→ the water injection station→ water injection well→ the wellhead”. The analysis results indicate that the temperature, pH value, and nutritional condition in the CO2 flooding gathering system are generally suitable for the growth and metabolism of sulphate-reducing bacteria (SRB). Therefore, H2S is produced because sulphate-reducing bacteria can easily breed in the CO2 gathering system.