考虑钻柱屈曲的环空压降计算

Calculation of annular pressure drop considering drill string buckling

孔令豪 何世明 汤明 袁兰峰 张光福

西南石油大学油气藏地质及开发工程国家重点实验室，四川 成都 610500

State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China

在定向井和水平井钻井过程中，准确预测钻柱屈曲条件下的环空压降，能有效优化定向井钻井参数、提高钻井效率。文中应用等效偏心度将屈曲环空简化为偏心环空，建立了钻柱屈曲条件下的环空压降简化模型，同时使用ANSYS Fluent软件进行了钻柱屈曲条件下的环空仿真模拟，并将简化模型结果与实验测试结果、Fluent仿真结果进行了对比验证。研究结果表明，在一个正弦屈曲周期内，环空压降比呈现先增大后减小的趋势，环空压降比随流性指数、环空内外径比和偏心度的增大而减小。文中建立的简化模型能够实现屈曲环空压降的准确预测，为定向井和水平井的井底压力计算提供了理论支撑。

During the process of directional well and horizontal well drilling, accurately predicting the annulus flow pressure drop under the condition of the drill string buckling（DSB） can effectively optimize the drilling parameters of the directional well and improve the drilling efficiency. In this article, using the equivalent eccentricity to simplify the buckling annulus to the eccentric annulus, a simplified model of the annulus flow pressure drop under the condition of the DSB is established. At the same time, ANSYS Fluent software is used to simulate the annulus flow under the condition of the DSB, and the simulation results are compared with the simplified model and experimental data. The results show that: in a sinusoidal buckling cycle, the pressure drop loss of the annulus increases first and then decreases; the ratio of annular pressure loss decreases as the fluid flow index, the annular inner and outer diameter ratio, and the eccentricity increase. The simplified model established in this study can accurately predict the pressure loss of the buckling annulus and provide theoretical support for the accurate prediction of the bottom hole pressure of directional and horizontal wells.

10.6056/dkyqt201903023