Potential and Cost Analysis of Carbon Sequestration in Co2 Plume Geothermal System

CO2 plume geothermal system (CPGS) can realize CO2 geological storage (CGS) and geothermal energy development at the same time. The thermal efficiency, CGS potential and unit cost of CPGS were analyzed by numerical simulation method, and the effects of injection-production wells spacing, injection pressure and injection temperature were compared. The results show that, (1) the thermal efficiency of CPGS can be divided into 5 stages, brief rise period, rapid decline period, slow recovery period, steady heat production period and recession period; (2) the injection-production wells spacing, injection pressure and injection temperature all affect the thermal efficiency of CPGS; (3) the injection-production wells spacing and the injection pressure have obvious influence on the CGS potential. The longer the injection-production wells spacing is, the higher the injection pressure is, the larger the CGS potential will be; (4) considering the CO2 capture cost and the heating benefit of CPGS, the CGS unit cost is estimated. The smaller the injection-production wells spacing is, the higher the injection pressure is, the lower the injection temperature is, the lower the CGS unit cost will be; (5) considering the carbon tax and drilling cost, the profit and loss of CPGS was estimated. The smaller the injection-production wells spacing is, the higher the injection pressure is, and the lower the injection temperature is, the easier it is for CPGS to return to profit.