Numerical Simulation of Geothermal Water Recharge Coupled with CO2 Geological Storage
Dissolution storage can effectively solve the leakage problem of CO2 geological storage,but subsurface dissolving is time-consuming and the cost of surface dissolution is high.A method of coupling geothermal water recharge and CO2 geological storage was proposed.CO2 and water were mixed at a certain depth in the recharge well to promote dissolution and reduce the dissolution cost.The multiphase flow model of CO2-geothermal water-salt in the wellbore and reservoir was established.The wellhead pressure and reservoir migration were simulated under different CO2 injection rates,mixing depths,and reservoir permeability conditions.The results showed that:(1)when the mass ratio of injected CO2 and water is modest,as the CO2 injection rate increases,the injection water and CO2 pressures remain at 1.0 MPa and 4.3 MPa,respectively;when the mass ratio of injected CO2 and water exceeds the CO2 saturation concentration under reservoir conditions,the injection pressure rises dramatically,and free CO2 accumulates above the reservoir;(2)when the mixing depth is between 390 m and 650 m,the water injection pressure remains steady;the injection pressure of CO2 rises as the mixing depth increases;(3)as the ratio of horizontal permeability to vertical permeability gradually increases,the water injection and CO2 injection pressures and the reservoir pressure decrease,and the difference in the migration distance of carbonated water at the top and bottom of the reservoir gradually increases.This method can make full use of geothermal recharge water to realize CO2 geological storage and reduce dissolution power consumption.
geothermal water rechargeCO2 geological storagewellbore mixingnumerical simulation
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