注CO2井井筒温度压力分布计算方法及应用 A Calculation Method and Application of Temperature and Pressure Distribution in CO2 Injection Wells

由于CO2在油藏流体中具有降低原油粘度和界面张力的特性，因此现场采用注CO2混相/非混相驱的办法来提高原油采收率。随着CO2驱油技术应用的不断深入，如何快速准确地判定在不同注入参数下CO2在注入井筒中沿井筒温度、压力及相态分布特征，以避免注入过冷CO2液体对地层造成冷伤害，获得最大的驱油效果是CO2注入工艺和开发设计亟待解决的问题。本文在综合考虑CO2压缩因子、比热容及粘度等参数计算的基础上，建立注CO2井井筒温度、压力计算模型。对M油田注CO2气井模拟计算结果与实测结果对比表明，该模型能够较好的应用于CO2注入井的井筒温度压力模拟计算，其计算结果可为CO2驱注入工艺及开发设计提供理论依据。 Because CO2 within the reservoir fluid has the characteristics of reducing the viscosity and interfacial tension of the oil, CO2 miscible or immiscible flooding is used in the field to enhance oil recovery. With the development of the application of CO2 flooding technology, there exists an urgent problem in CO2 injection process and developing design: how to estimate the temperature, pressure and phase distribution of CO2 in the wellbore under different injection parameters quickly and accurately, in order to avoid the cold damage to the formation caused by injecting supercold liquid CO2, and get the maximum flooding effect. Based on the consideration of CO2 compression factor, specific heat capacity and viscosity, this paper established a model to calculate the temperature and pressure of CO2 injection wells. Comparing the simulation results of CO2 gas wells in oil field M with the measured, it indicates that the model can be commendably applied to calculate the wellbore temperature and pressure of CO2 injection well. The calculation results can provide the theoretical basis for CO2 flooding process and developing design.