塔里木盆地大涝坝凝析气田循环注气开发设计

Study on cyclic gas injection technology for development of Dalaoba condensate field in Tarim basin

大涝坝凝析气田开发后期,地层压力降至露点压力以下,凝析油迅速析出,导致流体采出程度低,为了提高采出程度,进行了循环注气开发研究。分析了大涝坝凝析气田地质特征、流体相态特征,确定了凝析气藏注气地质条件,并根据在定容衰竭过程中介质作用对地层凝析油饱和度影响较大,对该凝析气藏采取注气保持压力方式开采。建立了气藏流体单井产出、注入方程,利用老井及新布井进行了注气方案优化。制定了凝析气藏循环注气布井方案,对循环注气开发指标进行了预测,形成了凝析气藏循环注气配套技术。通过气藏循环注气开发模拟,得出开发指标,并与衰竭方式开采指标对比,发现凝析油采收率大幅度提高,循环注气应用效果好。

During production tail of Dalaoba condensate field,formation pressure drops below dew point pressure and condensate oil sequently drops out,causing declined fluid recovery.For the purpose of recovery enhancement,study on cyclic gas injection tech-nology is carried out.Based on the analysis of geologic characteristics and fluid phase features,this paper concludes that gas injection is applicable for Dalaoba condensate field.And it is better to inject gas to keep up the pressure in such condensate gas reservoir during the course of constant volume depletion.Therefore,the equation for fluid productivity and injectivity in individual well is established and gas injection scheme is optimized by using mature well and newly drilled well.Through studies,the pattern of well for cyclic gas injection in condensate gas reservoir is finalized,the development index of cyclic gas injection is pre-determined and a complete system of cyclic gas injection technology for condensate gas reservoir is formed.Comparing the development index from cyclic gas injection simulation with that by natural depletion,it is found that condensate oil recovery by cyclic gas injection is greatly enhanced.As a result,the conclusion is drawn that cyclic gas injection technology is feasible for condensate gas reservoir development.