克拉美丽气田水淹气井气举硬举动态模拟

Dynamic Simulation of Gas-Lift Dead-Lift Unloading Process in Waterflooded Gas Wells of Kelameili Gas Field

气举因其适应性强,工艺灵活,广泛用于产水气井排液采气或水淹气井复产,但其卸载过程较为复杂,其卸载方式或工艺参数多凭经验确定,尤其对于气举硬举工艺。为此,基于动量守恒和质量守恒建立了气举硬举卸载过程数学模型,并利用有限差分方法对模型进行了求解。以克拉美丽气田水淹井DX180X井为例,采用气举硬举方式,考虑氮气气举和天然气气举,分别采用正、反举方式进行卸载动态模拟,分析了影响卸载的各因素,如注氮气或天然气,正、反举方式等,模拟了卸载过程中井口压力、井底压力等随时间的变化情况。为降低启动压力及减少井筒液体回流时间或回流量,推荐采用注氮气正举方式卸载,对于深井、地层压力较高或需连续油管气举硬举的水淹井尤为适用。通过实例模拟与分析为气举硬举的可行性研究、工艺设计及压缩机选择等提供了参考。

Because of its strong adaptability and flexibility,gas lift is widely used in dewatering gas recovery of water-producing gas wells or restoring production of water-flooded gas wells.However,the unloading process of gas lift is very complicated,and its unloading methods or process parameters are mostly determined by experience,especially for gas-lift dead-lift process.A mathematical model based on mass conservation and momentum conservation is established to describe the unloading process of gas-lift dead lift and the finite difference meth-od is used to solve the model.Taking the DX180X water-flooded gas well in Kelameili gas field for example and considering nitrogen gas lift and natural gas lift,dynamic simulation is performed for unloading process of normal lift and reverse lift,the influencing factors includ-ing nitrogen and natural gas injection,and normal and reverse lift are analyzed,and the changes of wellhead pressure and downhole pres-sure with time during unloading process are modeled.To lower the starting pressure and reduce liquid flowback time or flowback quantity,nitrogen-injection normal lift method is recommended,which is particularly applicable in deep wells and waterflooded wells with relatively high formation pressure or in which coiled tubing and gas-lift dead-lift are needed.Case modeling and analysis could provide references for feasibility study,design and compressor selection etc.of gas-lift dead-lift process.