衰竭底水气藏注CO2提高天然气采收率与碳封存机理OA北大核心CSTPCDEI
Mechanism of CO2 injection to enhance gas recovery and carbon storage in depleted bottom-water gas reservoirs
气藏注CO2 提高天然气采收率并实现碳封存有望成为大幅度提高天然气产量与碳减排协同的潜在关键技术.为了给底水气藏注CO2 高效开发提供指导,针对地层水盐度对CO2-CH4-H2O-NaCl体系相平衡影响、气藏注气过程中压力变化对CO2-CH4-H2O-NaCl体系相平衡影响、注采方案对注CO2 提高气藏采收率影响、盐度对注CO2 提产及封存影响等目前认识不清的问题开展了CO2-CH4-H2O-NaCl体系相平衡规律及注CO2 提采与封存数值模拟研究.研究结果表明:①随着盐度增加,CO2 和CH4 在盐水中的溶解度降低,液相的密度和黏度增加,盐度对气相性质几乎没有影响;②随着压力增加,CO2 和CH4 在液相中的溶解度均增加,气相、液相密度和黏度均增加,液相偏差因子随压力增加而增加,气相偏差因子先减小后增加;③同注同采方案CH4 产量更稳定且产出的CO2 少,而先注后采方案则会加速CO2 与CH4 的混合,CO2 封存量低,前者更适合注CO2 提采及封存;④在不考虑盐析效应的前提下,盐度对CH4 采收率和CO2 封存量的影响几乎可以忽略不计,不同盐度的衰竭底水气藏中CH4 采收率均超过80%、CO2 封存率均超过99%,短期注CO2 过程中,CO2 主要以气态或超临界态的形式被封存,少部分CO2 溶解在液相中,100年后CO2 在液相中的溶解质量分数约为5%.结论认为,衰竭底水气藏注CO2 能增压补能、驱替置换残余天然气,提高采收率并实现碳封存.
CO2 injection in gas reservoirs to enhance gas recovery and carbon storage is a potential key technology to significantly improve gas production and reduce carbon emission.In order to provide a guidance for the efficient development of bottom-water gas reservoirs,this paper studies the influence of formation water salinity on the phase equilibrium of the CO2-H2O-CH4-salt system,the influence of pressure change on the phase equilibrium of the CO2-H2O-CH4-salt system in the process of injecting CO2 into the gas reservoir,the influence of injection and production scheme on CO2 EOR,and the influence of salinity on CO2 EOR and storage.And the following research results are obtained.First,with the increase of salinity,the dissolubility of CO2 and CH4 in salt water decreases,and the density and viscosity of liquid phase increase.Salinity has little influence on the properties of gas phase.Second,with the increase of pressure,the dissolubility of CO2 and CH4 in liquid phase,the density and viscosity of gas and liquid phases,and the deviation factor of liquid phase increase,while the deviation factor of gas phase decreases first and then increases.Third,in the case of simultaneous injection and production,CH4 production rate is stable,and less CO2 is produced.In the case of injection first and then production,the mixing of CO2 and CH4 is accelerated,and the amount of CO2 storage is small.It is indicated that the former case is more suitable for CO2 EOR and storage.Fourth,in the precondition without considering the salting-out effect,the influence of salinity on CH4 recovery factor and CO2 storage is nearly negligible.No matter what salinity of the depleted bottom-water gas reservoir is,the CH4 recovery factor is over 80%,and the CO2 storage rate is over 99%.In the process of short-term CO2 injection,CO2 is stored mainly in the form of gaseous or supercritical state,with a little dissolved in liquid.And the mass fraction of CO2 dissolved in liquid after 100 years is about 5%.In conclusion,CO2 injection in depleted bottom-water gas reservoirs can enhance gas recovery and realize CO2 storage.
张烈辉;熊伟;赵玉龙;文绍牧;曹正林;刘莉莉;罗山贵;汪永朝
油气藏地质及开发工程全国重点实验室·西南石油大学中国石油西南油气田公司中国石油勘探开发研究院中国石油长庆油田公司勘探开发研究院
石油、天然气工程
衰竭底水气藏注二氧化碳提高气藏采收率碳封存e-CPA状态方程CO2-CH4-H2O-Nacl体系相态变化规律
Depleted bottom-water gas reservoirCO2 injectionEnhanced gas recoveryCarbon storagee-CPA equation of stateCO2-CH4-H2O-salt systemPhase transition law
《天然气工业》 2024 (004)
25-38 / 14
国家自然科学基金区域创新发展联合基金项目"四川盆地有水气藏CO2驱提高采收率及其有效封存研究"(编号:U23A2022).
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