注CO_2井筒温度场分布规律模拟研究

Simulation of temperature field for CO_2 injection wellbore

注气过程中,低温CO2与井筒、地层存在热交换,井底与近井油层温度将明显下降,降低原油黏度,还可能造成蜡沉积和水合物生成,影响生产。为了优化注气参数,提高注气开发效果,通过对注气井筒与地层传热机理的研究,建立了综合考虑沿程流体相态及热物理性质变化的井筒温度、压力场数学模型,利用四阶龙格库塔法求解,并开发了注CO2井筒温度场数值模拟软件。通过实例验证了模型及解法的适用性,模拟并分析了井筒温度及CO2物性变化规律。

In the process of the gas injection, there is a process of heat transfer among low temperature CO2, wellbore and adjacent formation. The temperature of bottom hole and adjacent oil reservoir will decrease, resulting in oil viscosity decreasing. The wax will deposit and the carbon dioxide hydrate will be generated, which can cause damage to oil reservoir by low temperature and affect the production. In order to optimize the gas injection parameters and enhance the gas injection development effect, this paper builds the mathematical model for predicting the temperature and pressure distribution by studying the heat transfer within wellbore and reservoir, which comprehensively considers the fluid phase behavior and thermophysical properties. By the Four-Order Runge-Kutta Method, the Numerical Simulation Software of Wellbore Temperature Field for CO2 injection has been developed. The suitability of this method is approved by example analysis. The wellbore temperature and CO2 physical properties distribution are simulated and analyzed.