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

摘要: 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。

Abstract: 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.