局部反循环打捞装置数值模拟

Numerical simulation of local reverse circulation salvage device

为了明确常规局部反循环洗井装置在井下形成反循环的机理及其目前洗井效果不理想的原因,解决其在应用过程中碎屑提取率低的问题,采用计算流体力学方法,建立该装置洗井作业时的孔底固液两相流场计算模型,分析液相洗井介质在冲洗碎屑过程中的压力场、速度场分布及湍流特征。模拟计算得出:液相洗井介质的压力、流速及湍动能耗散主要发生在进入孔底流场前的两次出水孔换向过程中,导致其对孔底中部的碎屑冲洗能力不足,部分碎屑滞留在孔底中部。为改善反循环洗井装置的洗井效果,可改进下出水孔的结构,将下出水孔位置适当下移或缩小下出水孔直径,通过增大孔底处洗井介质流速来提升其对碎屑的携带能力。研究结果可为局部反循环打捞装置的优化设计提供参考。

In order to make clear the mechanism of reverse circulation formation by conventional partial reverse circulation washing device in underground and the cause of the unsatisfactory washing effect at present,as well as to solve the problem of low chip extraction rate in the application process,computational fluid dynamics method is used to establish the calculation model of solid-liquid two-phase flow field of hole bottom in the washing operation of the device,and the pressure field distribution,the velocity field distribution and the turbulence characteristics of the liquid phase washing media in the process of flush debris are analyzed.The simulation calculation shows that the pressure,flow velocity and turbulent kinetic energy dissipation of liquid phase washing media mainly occurr in the process of twice reversing in the outlet hole before entering the hole bottom flow field,reducing the ability to clean the debris in the middle of the hole,and causing part of the debris trapped in the middle of the hole.In order to improve the washing effect of reverse circulation well washing device,the structure of the bottom outlet hole can be improved,shifting downward the lower outlet hole position appropriately or reducing the diameter of outlet hole,increasing the flow rate of the washing medium at the bottom of the hole to improve the carrying capacity of the well washing medium to the debris.The research results may provide reference for the optimal design of the local reverse circulation salvage device.