Analysis of the impact of the reinjection of gases on the mass flow rate from production wells at varying reservoir conditions

Greenhouse gas emissions from geothermal power plants are a barrier to the growth of geothermal energy at present and in the future. The discharge of the gases associated with the electricity generation process from geothermal fluids to the atmosphere contradicts New Zealand's target to achieve net-zero emissions by 2050. These gases are dominated by carbon dioxide. Reinjecting the gases back into the reservoir by dissolving them in the separated brine could be one way of reducing emissions from the geothermal electricity generation process. Besides reducing greenhouse gas emissions, reinjection may help in mitigating silica scaling problems by making the reservoir fluids more acidic. This helps in the dissolution of minerals, which further helps in improving the permeability of the reservoir and contributes to variation in output from the production well. This paper discusses an analysis of the impact of the concentration of gases present in the reservoir on the mass flow rate from the production well. This is a result of changes in the thermodynamic properties of the fluid present in the reservoir. The analysis of the main parameters that contribute to the predicted mass flows will be presented. Well flows are estimated from production wells over the range of conditions found in New Zealand's geothermal production fields. It demonstrates the impact of reinjection of gases on different types of geothermal reservoirs through changes in mass flow rate from the production well.