地热井钻井液对井壁温度分布的影响研究

Study on influence of drilling fluids on temperature distribution over the borehole wall in geothermal wells

地热井钻井作业时,井深越大,井眼温度越高,给钻探施工造成的难度越大,因此有必要研究井内循环温度分布。通过分析钻井液循环时热量传导过程,利用井筒温度控制方程,结合雄安新区地热井工程实例中的各项参数,使用全隐式有限差分法求解方程,求解井内钻井液循环时各部分的温度分布。且通过方程模拟研究了钻井液的密度、粘度、排量等工程参数对井壁温度分布的影响,结果表明:钻井液密度、粘度、排量越大,井壁温度越低,井底附近的井壁温度降低幅度越大,其中钻井液的排量改变对井壁温度分布的影响最大。模拟研究结果对于现场施工设计有一定的参考价值。

In geothermal well drilling, borehole temperatures increase with depths, making drilling more difficult. Therefore, it is necessary to study the circulation temperature distribution in the well. With analysis of the heat conduction process during drilling fluid circulation, and in view of various thermal well parameters in Xiongan New Area, the wellbore temperature control equation is adopted, and the fully implicit finite difference method is used to solve the equation to find the temperature distribution over each well section during drilling fluid circulation in the well. The influence of the drilling fluid density, viscosity and displacement on the wellbore temperature distribution is studied by equation simulation. Results show that the higher the drilling fluid displacement, density or viscosity is, the lower the wall temperature is;and the more the wellbore wall temperature near the bottom decreases. The displacement change of drilling fluid has the greatest influence on the borehole wall temperature distribution. The results of the simulation study provide some reference for the drilling design.