液力驱动无绳索取心系统泥浆正反循环切换机构设计及其流体通道优化

Design of slurry forward/reverse circulation switching mechanism and optimization of its fluid channel in hydrodynamic-driven cordless coring system

摘要:

为解决超长水平孔取心钻探效率低的问题，提出通过泥浆液力驱动完成内管总成的投送和回收的无绳取心钻进工艺。为此，本文设计了一种辅助内管投送与回收的孔口泥浆正反循环切换机构。该机构通过两个双通道球阀的相互配合，改变泥浆流动方向，就可实现正反循环的切换。通过ANSYS软件，对正反循环切换机构的L形双通道进行了仿真模拟，结果显示，流体通过L形通道后，高速流体只占总量的50%，流体经过球阀通道的压力降为1008.1 Pa，且靠近通道内侧的流体会产生大量紊乱，产生了不同程度的回流。为此，将通道形状进行了优化，将原来的L形通道改为圆弧形通道，仿真模拟结果显示，流体通过圆弧形通道后，高速流体占总量的90%，流体经过球阀通道的压力降仅为105.3 Pa，且流体迹线整体平滑，仅有少量流体发生回流。优化后的流体通道，有效降低了水头压力损耗，保证了流体的稳定运移。

Abstract:

In order to solve the problem of low efficiency of core drilling in ultra-long horizontal holes， a cordless core drilling process is proposed to complete the delivery and recovery of the inner tube assembly by mud hydraulic drive. To this end， this paper designs a positive/reverse circulation switching mechanism for the borehole mud that assists the delivery and recovery of the inner tube. This mechanism can realize the positive/reverse circulation switching by changing the mud flow direction through the mutual cooperation of two dual-channel ball valves. Through the ANSYS software， the L type double channel of the positive/reverse circulation switching mechanism is simulated， and the results show that after the fluid passes through the L type channel， the high-velocity fluid only accounts for 50% of the total amount of fluid， and the pressure drop of the fluid through the ball valve channel is 1008.1Pa， and the fluid near the inside of the channel will produce a lot of turbulence， resulting in different degrees of backflow. For this reason， the shape of the channel was optimized， the original L channel was changed to a circular channel， simulation results show that the fluid through the circular channel， high-speed fluid accounted for 90% of the total amount of fluid through the ball valve channel pressure drop is only 105.3Pa， and the fluid trace overall smooth， only a small amount of fluid reflux occurred. The optimized fluid channel is effective in reducing the pressure drop through the ball valve. The optimized fluid channel effectively reduces the head pressure loss and ensures the stable transportation of the fluid.