In the context of the global“Carbon Peaking and Carbon Neutrality”initiative,the injection of carbon dioxide(CO_(2))into depleted gas reservoirs represents a dual-purpose strategy—facilitating long-term carbon sequ...In the context of the global“Carbon Peaking and Carbon Neutrality”initiative,the injection of carbon dioxide(CO_(2))into depleted gas reservoirs represents a dual-purpose strategy—facilitating long-term carbon sequestration while enhancing hydrocarbon recovery.However,variations in injection parameters at the wellhead can exert pronounced effects on the temperature and pressure conditions at the bottomof the well.These variations,in turn,influence the geomechanical behavior of reservoir rocks and the displacement efficiency of CO_(2) within the formation.Precise prediction of downhole thermodynamic conditions is therefore essential for optimizing injection performance and ensuring reservoir stability.To address this need,the present study develops a robust coupled model to simulate the behavior of CO_(2) within the wellbore,incorporating momentum conservation,mass continuity,and steady-state heat transfer equations.Validation against field-measured data confirms the model’s reliability and applicability under realworld operating conditions.Parametric analysis reveals the complex influence of injection conditions on bottom-hole states.Injection pressure primarily affects downhole pressure,exerting minimal influence on temperature.In contrast,low injection temperatures and elevated flow rates lead to reduced bottom-hole temperatures and heightened pressures.Owing to the interplay of convective and conductive heat transfer mechanisms,the relationship between injection rate and bottom-hole temperature exhibits nonlinearity.Notably,injection scenarios characterized by low temperature,high pressure,and high velocity promote a deeper penetration of the CO_(2) critical phase transition point within the tubing.Among the parameters examined,injection temperature emerges as the dominant factor affecting the depth of CO_(2)’s phase transformation,followed by injection rate,with pressure exerting the least influence.A strong correlation is observed between injection rate and the depth of the critical phase transition,offering a practical framework for tailoring injection strategies to enhance both CO_(2) storage capacity and recovery efficiency.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52304046,52204051,52174033 and U23B20156).
文摘In the context of the global“Carbon Peaking and Carbon Neutrality”initiative,the injection of carbon dioxide(CO_(2))into depleted gas reservoirs represents a dual-purpose strategy—facilitating long-term carbon sequestration while enhancing hydrocarbon recovery.However,variations in injection parameters at the wellhead can exert pronounced effects on the temperature and pressure conditions at the bottomof the well.These variations,in turn,influence the geomechanical behavior of reservoir rocks and the displacement efficiency of CO_(2) within the formation.Precise prediction of downhole thermodynamic conditions is therefore essential for optimizing injection performance and ensuring reservoir stability.To address this need,the present study develops a robust coupled model to simulate the behavior of CO_(2) within the wellbore,incorporating momentum conservation,mass continuity,and steady-state heat transfer equations.Validation against field-measured data confirms the model’s reliability and applicability under realworld operating conditions.Parametric analysis reveals the complex influence of injection conditions on bottom-hole states.Injection pressure primarily affects downhole pressure,exerting minimal influence on temperature.In contrast,low injection temperatures and elevated flow rates lead to reduced bottom-hole temperatures and heightened pressures.Owing to the interplay of convective and conductive heat transfer mechanisms,the relationship between injection rate and bottom-hole temperature exhibits nonlinearity.Notably,injection scenarios characterized by low temperature,high pressure,and high velocity promote a deeper penetration of the CO_(2) critical phase transition point within the tubing.Among the parameters examined,injection temperature emerges as the dominant factor affecting the depth of CO_(2)’s phase transformation,followed by injection rate,with pressure exerting the least influence.A strong correlation is observed between injection rate and the depth of the critical phase transition,offering a practical framework for tailoring injection strategies to enhance both CO_(2) storage capacity and recovery efficiency.
