Research On The Nozzle Device Of The Particle Impact Drilling System

The purpose of particles impact drilling technology is increasing the rate of penetration when drilling extra-hard and strong-abrasive rocks, and the technology becomes the world’s most potential drilling technology for deep wells and ultra-deep well. The most important part of the drilling technology is the nozzles which speed the particles.In this paper, based on the acceleration mechanism of five different nozzles, that is cylindrical nozzle model, tapered nozzle model, straight-taper nozzle model, streamline nozzle model and elliptical nozzle, set the speed of the particles and drilling fluid an appropriate ratio in the outlet the same, after developing the mathematical models, the simulation are finished based on FLUENT, and discusse how the flow characteristics are, and the better types of nozzles model are straight-taper nozzle model, streamline nozzle model and elliptical nozzle.The incident angle of nozzles depend on the locations in the PID(Particle Impact Drilling), the center one be 0 degree and the edge one with a certain angle of 20 degree for spraying-up. After the simulation of different types of nozzles, the streamline nozzle model and elliptical nozzle both are better than straight-taper nozzle model in flow convergence and acceleration ratio, also the approximate constant interval distance is enough for rock breaking,And the PID is designed based on the simulation, a center nozzle with 4 nozzles uniform distribution on the edge, and the distance of each between the center one is the 30 mm.Make sure the velocities of two-phase fluids satisfy the need of rock breaking when drilling extra-hard and strong-abrasive rocks, both simulation of the static and dynamic flow field are finished, discuss the acceleration and pressure characteristics of the two-phase fluids,the results show the PID can meet the needs of engineering work.A series of laboratory experiments of particle impact drilling technology, the particle and drilling fluid is accelerated through the nozzles of PID, the results prove the simulation of PID design is available, and the acceleration characters and rock breaking consequence of streamline nozzle is better than that of straight-taper nozzle model.