Design And Experiment Study Of Negative Pressure Jet Balanced Particle Injection System

Particle impact drilling technology provides technical support for improving the drilling rate of deep hard formations and strong abrasive formations.The particle injection system is the core part and the premise of particle impact drilling.In this paper,according to the existing defects and deficiencies of the existing injection system,the theoretical analysis,numerical simulation and experimental verification are used to optimize the system.A set of negative pressure The injection-balanced particle injection system solves the problems of difficult control of the differential pressure in the negative injection particle injection system,easy blockage of the high pressure particle tank discharge port and unstable particle injection,and promotes the negative pressure injection-equilibrium particle Injecting system on-site promotion and application.The discrete element method was used to calculate the liquid bridge force.The differential equation of particle motion in the high pressure particle tank was established.The particle flow in the high pressure particle tank was numerically simulated.The main reason for particle blockage and particle injection instability was analyzed.the reason.Based on the pulsation degree of particles injection process,the influence of half cone angle of high pressure particle tank on particle motion was studied numerically.The optimum half cone angle of high pressure particle tank was optimized.The numerical model of vacuum injection-equilibrium particle injection system was established,and the particle injection process was numerically simulated.The effects of the ratio of the three key parameters of fluidized nozzle diameter,throttle ring diameter and discharge port diameter on the particle flow stability and particle volume fraction were studied.The influences of the pulsation degree and particle volume fraction The structural parameters were optimized for the criterion.According to the field work requirements of particle injection system,combined with the flow characteristics and numerical simulation results of particles in high pressure particle tank,the high pressure particle tank,anti-blocking mixing system,pressure balance system and particle Gravity control system for the overall design,at the same time the system key components of the design and system seal design.The designed negative pressure injectionequilibrium particles were processed and assembled.Laboratory experiments were carried out.Particle volume fractions of 1.0mm,1.7mm and 2.0mm were obtained by changing the choke rings with different diameters.Calibration experiment.The experimental results show that the designed negative pressure injection-balanced particle injection system can inject particles continuously and stably,and obtain the particle volume fraction suitable for drilling site.