Possibility to Use CO2 as Working Fluid from Temporally Closed Hydrocarbon Wells Generate Energy

Abstract

Hungary’s rather good geothermal potential is well-known. Based on the 2016 Geothermal Atlas of Hungary, 1622 thermal wells produce hot water for direct heat utilization, and about 170 abandoned or temporarily closed oil and gas wells have been rated as very good geothermal sources. Hungary also has natural gas reservoirs with high CO2 content, in some cases even higher than 90%. The low critical pressure of the CO2 makes it ideal as a heat-bearing medium and working fluid in a geothermal system. This paper investigates how we could harvest these wells’ geothermal potential using supercritical CO2 as a working fluid. To this end, a mathematical model has been developed to determine the heat transfer mechanism in the well.