起下钻时井眼内动态波动压力的预测

PREDICTION FOR WELLBORE DYNAMIC SURGE PRESSURE WHILE TRIPPING A DRILLPIPE

以流体力学不稳定流动的基本理论为基础，建立了钻井起下钻作业过程中井眼内动态波动压力预测的理论模型。介绍了动态波动压力的基本方程及求解该方程的特征线差分和方格网加插值的求解方法。给出了考虑不同井身结构、钻具组合、钻头和喷嘴（包括泥包钻头）、起下速度和加速度变化等因素后边界条件及初始条件的处理方法。以算例的形式介绍了模型的应用情况。

This paper presents a theoretical model for predicting dynamic surge pressurebased on the theory of fluld mechanics on unsteady state flow while tripping a drillpipe in awellbore.The basic partial differential equations for describing dynamic surge pressure aregiven. The characterized method, finite-difference technique,grid and interpolation methodare used to solve the basic equations. The methods are proposed for determining boundary andinitial conditions when considering hole configuration,drillpipe assembly,drill-bit,jetnozzles of drill-bit(including balling bit), variabilities of tripping velocity and acceleration.The paper gives an example for the application of the model.