钻杆流场诱导腐蚀模拟

Numerical simulation of flow field induced corrosion in drill pipe

钻杆是钻柱系统的重要组成部分,在工作中除要承受多种载荷外,还要受到钻井液等流体的诱导腐蚀,是钻柱系统的薄弱环节,现场实际工作中钻杆失效事故更是频繁发生。而钻杆失效高发区域便为加厚过渡带,传统上的钻杆失效数值模拟分析采用的主要方法是建立钻杆加厚过渡带的力学模型,从该区域受到载荷的情况下分析其等效应力的分布和应力集中系数的大小。针对钻杆受到钻井液诱导腐蚀刺穿的情况,从流体力学的角度进行数值模拟分析。以准127 mm的API钻杆的8种不同结构为研究对象,采用有限体积法建立数学模型。基于8种不同结构和不同钻井液流速情况,对钻杆内部的流场变化进行数值模拟,获得了钻井液在钻杆加厚过渡带这一区域的压力场分布规律。研究结果对优化钻杆加厚带尺寸,合理钻井液流速工艺具有一定的参考作用。

Drill pipe is an important component of drill string system and is the weak link of drill string system. It undertakes the drilling fluid induced corrosion except the various loads. So the drill pipe failure accidents frequently happen in practical operation. The high-risk areas with drill pipe failure are drill pipe upset transition area. Numerical simulation analysis of traditional pipe failure mainly adopts the methods that establish the mechanical model of drill pipe upset transition area. From the undertaking load in this area, this paper analyzed the equivalent stress distribution, stress concentration coefficient and the numerical simulation results from the viewpoint of fluid mechanics and aimed at the drill pipe corrosion and pierce by the fluid in the pipe. Based on different structure of drill pipe upset transition area and fluid flowing velocities, used the 127 mm API standard drill pipe with 8 different structures and the mathematical model established by finite volume method, the pressure field distribution was acquired through the simulation of the flow field in the drill pipe. The study results can provide a reference for the optimization of drilling pipe size and the reasonable improvement of drilling fluid technology.