Study on Mechanism and Regularity of Rock Breaking by Pulsed Water Injection with Particles

In recent years, the drilling technology applied to deep and ultra-deep formations has developed rapidly, but the drilling speed for hard formations is low. Therefore, it is very important to study the drilling methods for deep and hard strata. Particle pulsed jet drilling is a new drilling method based on particle jet impact drilling technology and high-pressure pulsed water jet impact drilling technology. In this paper, the mathematical models of the shear layer amplification coefficient and wave velocity are established based on a similar network theory, and the motion equations of a single particle and particle swarm are established according to the motion of particles in a pulsed jet environment. Then, based on the self-designed particle jet impact rock-breaking experimental platform, the numerical simulation results are compared, analyzed, and verified. The results show that the rock-breaking efficiency increases with the increase in the average velocity of the particle pulsed jet. When the average speed exceeds 160 m/s, the rock-breaking efficiency increases significantly. With the increase in the particle concentration, the rock-breaking efficiency of the particle pulsed jet also increases, but there is an optimal value. When the concentration is too high, the impact of particles on the rock is affected by the collision between particles, and the wear of the drill intensifies. This research is helpful for understanding deep-well drilling-speed-increasing technology and promotes the development and engineering applications of particle jet impact drilling theory.