Particle Impact Drilling (PID) is a new technology to effectively improve the rate of penetration (ROP) for oil and gas drilling in hard and strongly abrasive formations. In this paper, numerical simulation method is used to analyse the motion characteristics and the modulation method of particle swarm in high-pressure tank for the particle injection system based on differential pressure ejection in PID. The numerical simulation results show that: when there is no modulation elements, the motion of particle swarm in the high-pressure tank follows an asymmetric funnel flow with pulsating state, which could be divided into vertical flow domain, fast flow domain, slow flow domain and stagnation domain. The unstable dynamic arching effect of the funnel flow, the viscous effect of the liquid bridge force and the collapsing effect of the particle swarm could probably lead to the blockage of the discharge port of the high-pressure tank. When the semiapex angles of the high-pressure tank decreases, the volume flow rate of particles increases and the stagnation domain becomes smaller, but it becomes easier to form arching and blockage. The modelling results indicate that the pulsation of the funnel flow is minimum when the semiapex angle is 45° without the mutilation element, which means the funnel flow of the particle swarm is relatively stable. By introducing a conical modulating element above the discharge port, the unstable funnel flow of the particle swarm could be transformed to an overall uniform flow. The modelling results indicate that the installation height of the modulation element has the greatest influence on the pulsation degree. The optimized parameters for the conical modulation element based on numerical modelling tests are 70° for the vertex angle, 35 mm for the length of the flank and 70 mm for the installation heigh.

中文翻译：

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颗粒冲击钻高压罐内钢质颗粒群运动分析与调制

颗粒冲击钻井（PID）是一种有效提高坚硬、强磨蚀地层油气钻井钻速（ROP）的新技术。本文采用数值模拟方法，对基于PID差压喷射的颗粒喷射系统中高压罐内颗粒群的运动特性及调制方法进行了分析。数值模拟结果表明:当没有调制元件时,高压罐内粒子群的运动呈脉动状态的非对称漏斗流,可分为垂直流域、快流域、慢流域和停滞域。漏斗流的不稳定动力拱效应、液桥力的粘性效应和粒子群的塌陷效应可能导致高压罐排出口的堵塞。当高压罐半顶角减小时，颗粒体积流量增大，滞止域变小，但更容易形成起拱和堵塞。模拟结果表明，在没有残缺单元的情况下，当半顶角为45°时，漏斗流的脉动最小，这意味着粒子群的漏斗流相对稳定。通过在出料口上方引入锥形调节元件，可以将颗粒群不稳定的漏斗流转变为整体均匀的流动。建模结果表明调制元件的安装高度对脉动程度影响最大。根据数值模拟试验，圆锥形调制元件的优化参数为：顶角70°、侧面长度35 mm、安装高度70 mm。