边水碳酸盐岩气藏注CO2提采及封存潜力预测OA

CO2-enhanced oil recovery(EOR)technology has been widely applied to various oil reservoirs.However,there are few studies on CO2-enhanced gas recovery(EGR)and the sequestration capabilities of carbonate gas reservoirs with edge water in China.To understand the EGR mechanisms and CO2 sequestration potential within carbonate gas reservoirs with edge water,this work used numerical simulation techniques to model CO2 flooding performance in the M carbonate gas reservoir with edge water.First,wells suitable for CO2 injection were selected.Second,CO2 flooding plan was designed for the M carbonate gas reservoirs with edge water.Based on the optimal plan,the cumulative natural gas production and CO2 sequestration performance were predicted.Finally,the mechanisms of EGR and CO2 sequestration in carbonate gas reservoirs with edge water were revealed.Results showed that the optimal plan consisted of three injection wells and seven production wells.The gas injection rate for the total M reservoir area was set at 22.5×104 m3·d-1,with a total injection volume of 16×108 m3 during the gas flooding stage.The shut-in time was established based on the m ole fraction of CO2 in the production well,which was targeted to reach 10%-30%.The gas production rate for the entire area is maintained at 22.5×104 m3·d-1,with the optimal gas drive plan spanning 19.5 years.Remarkably,the recovery was 84.5%under this plan.Several conclusions were drawn from this study.First,following injection,CO2 diffuses from the injection well towards the periphery of the reservoir,moving from higher to lower elevations.This diffusion process led to an increase in gas density within the formation.Water saturation near the injection well exhibits a decreasing trend,and the gas-water interface decreases significantly(50-100 m),which can effectively suppress the invasion of edge water.Second,the effective CO2 sequestration capacity is predicted for 14.29×106 t under the optimal plan.This total capacity is comprised of supercritical sequestration(13.56×106 t),solution sequestration(0.53×106 t),and mineral sequestration(0.20×106 t).The minor error between the numerical simulation results and the mathematical model predictions further validated the accuracy and reliability of the findings.The results of the present study are significant.The M gas reservoir exhibits significant potential for CO2 EGR and storage.The findings provide scientific guidance for the efficient development of carbonate gas reservoirs with edge water and offer crucial data support for the application of carbon emission reduction technologies.In conclusion,CO2 EGR and sequestration in carbonate gas reservoirs with edge water can maximize economic benefits and contribute towards achieving the dual-carbon target.