井下多股淹没射流水力清岩能力分析

研究石油钻井井下射流的水力清岩能力对钻井业有重要意义。本文借助于预处理方法和多块网格对接技术由计算机数值模拟了形状复杂的钻井PDC钻头井底下的多股淹没射流流场。为体现井底有岩屑时射流场对其的清洗作用。文中借助河流泥沙运动理论，分析了岩屑在井下的受力与运动以考虑固相的作用。因岩屑主要为推移运动。在井底除环空外的大部分地方可简化视为二维运动。提出了钻头井底水力清岩能力的体现参数-水力挟岩力。并通过数值模拟显示了井下流场，描述了转速，射流流量，喷嘴面积，射流雷诺数及井下过流空间等流场控制参数对井底水力清岩能力的不同影响，指出相关水力参数在射流时的优化方向。为复杂的井底流场控制和钻头的合理设计做探索基础。

A Research on Hydraulic Capability Analysis to Clean Solid Particles at Flow Field of Submerged Jetting

It is a significant meaning to research the hydraulic capability to clean solid particles at flow field of submerged jetting on PDC drill bit. Coupled with the analysis of force and motion of solid particles according to the theory of sediment movement in the rivers, a new parameter embodying the capability of mud to clean solid particles at bottom hole was brought out, with the aid of numerical simulation on flow field of a certain real drill bit. Finally the effects of control parameters, as rotary speed, mass flow of jetting, size of nozzles, Renold number of jetting, flow space at bottom hole on flow field and hydraulic capability to entrain solid particles were described and explained. All the research is paving the way for controlling flow of bottom hole and optimal design of drill bit.