气液两相流压降模型在欠平衡钻井中的应用

分别利用Hasan kabir和Ansari气液两相流压降模型，分析了欠平衡钻井过程中的井筒压降问题，建立了欠平衡钻井流型判别及压降计算的数学物理模型，并用FORTRAN90进行了编程计算，模拟了欠平衡钻井过程。通过分析井口回压、注气量以及注液量等欠平衡钻井参数发生变化对井底压力的影响，确定了欠平衡钻井井底压力控制方法。理论计算结果与实验数据对比分析表明，Hasan－Kabir预测压力的相对误差在10%以内，Ansari的相对误差在5%以内。因此，建议在欠平衡钻井设计中应用预测精度较高的Ansari方法。

APPLICATION OF PRESSURE DROP MODEL OF GAS/LIQUID TWO-PHASE FLOW IN UBD DRILLING

Hasan-Kabir's pressure-drop model and Ansari's pressure-drop model for gas/liquid two-phase flow are used to predict the pressure drop in the wellbore during the underbalanced drilling(UBD).The mathematical physics models of UBD are established to identify different UBD flow patterns and calculate pressure drop,and program is compiled with FORTRAN90,the UBD process is simulated.Through the analysis of the effects of wellhead backpressure,gas rate and liquid rate on the bottomhole pressure,the method used to control the bottom hole pressure during UBD is determined.The comparison between theoretical calculation results and the experimental data shows that the relative error of Hasan-Kabir model is less than 10%,and Ansari model less than 5%.So the Ansari Method is recommended to use in UBD design because of its higher prediction accuracy.