双向耦合冲击钻具设计与数值模拟

Design and Numerical Simulation of Bidirectional Coupling Percussion Drilling Tool

为了提升硬质地层破岩效率,满足深井、超深井钻井的提速需求,结合扭转冲击破岩及水力脉冲空化射流提速方法的特点,提出了双向耦合冲击钻井提速方法,并基于该方法研制了新型双向耦合冲击钻具。分析了双向耦合冲击提速方法及工具的结构特点,并从理论上进行了可行性分析与论证。采用数值模拟的方式分析了脉冲射流结构流场压力变化规律和脉动特性。分析结果表明:随着排量的增大,脉冲结构入口和出口压力脉动幅值呈线性增大,压降呈幂次方增长;叶轮叶片数量增加,入口和出口压力脉动幅值减小,但对压降的影响不大;叶轮直径增大,出口压力脉动幅值和压降均增大;振荡腔体中心流道直径增大,出口压力脉动幅值和压降均减小。研究结果可为双向耦合冲击钻具的系统化设计及现场应用提供理论支撑。

In order to improve the rock-breaking efficiency in hard formations and meet the needs of deep and ultra-deep well drilling, the bidirectional coupling percussion drilling technique was proposed on the basis of torsional impact rock breaking and hydraulic pulsed cavitating jet assisted drilling, and a new bidirectional coupling percussion drilling tool was developed. In this paper, the characteristics of the bidirectional coupling percussion drilling technique and tool structure were analyzed, and the feasibility analysis and demonstration were conducted theoretically. The flow field pressure variation and pulsation characteristics of the pulse structure were analyzed by numerical simulation. The results show that: with the increase of the displacement, the pulsation amplitude of the inlet and outlet pressures of the pulse structure increases linearly, and the pressure drop increases in a power-law;with the increase of the number of impeller blades, the inlet and outlet pressures decreases, but the pressure drop is not affected greatly;with the increase of impeller diameter, the pulsation amplitude of outlet pressure and the pressure drop increase;and with the increase of the diameter of the central passage in the oscillating cavity, the pulsation amplitude of outlet pressure and the pressure drop decrease. The study results provide theoretical support for the systematic design and field application of bidirectional coupling percussion drilling tools.