Structure Design And Simulation Analysis Of Particle Impact Drill Bit

With oil exploration and development moving to deep formation and unconventional oil and gas,it is particularly difficult to drill deep well and hard formation.Particle impact rock breaking technology is to use the steel particles in the particle jet to impact the formation at high frequency and high speed for rock breaking,which can significantly reduce the critical pressure of rock breaking and effectively improve the drilling speed.The effect of particle impact drilling technology is remarkable,but it also reflects the high cost of equipment input,complex system,serious pipeline erosion and other problems,which can not form large-scale industrial popularization.This paper proposes a new type of particle impact drill,which does not need external equipment to inject steel particles,and uses the cuttings generated by the drill to directly modulate the particle jet inside the drill,which is used to assist the rock breaking.In this paper,the technology does not need to increase the surface equipment,simplify the particle impact drilling technology process,and has broad application prospects in the field.Specific research contents are as follows:(1)Based on particle impact drilling technology,combined with the principle of ejector,a new type of particle impact drill is proposed.The design theory and working principle of particle impact drill are studied,and the rational design of particle impact drill is carried out.(2)Combined with the ejector structure,design the ejector structure of particle impact drill bit;Drill mechanical structure from the bit crown,tooth design and other aspects of comprehensive design;Design the hydraulic structure of the bit,complete the nozzle Angle and position design,and realize the full coverage of particle jet at the bottom of the hole;Through the numerical simulation of single nozzle,the acceleration ability of cone straight nozzle and streamline nozzle to debris particles is compared and analyzed.(3)The bottomhole fluid domain model of full-size bit was constructed,and the feasibility of self-circulation of particle impact bit was verified by numerical simulation;The influence law of the structural parameters of drill ejector is studied.The bottom hole flow field pattern was analyzed,and the best nozzle combination was selected by comparing four bit nozzle combinations.(4)Build the principle prototype test system,design and process the drill principle prototype,and carry out laboratory test research.Verify the feasibility of the bit self-circulation,and analyze the influence of the size of the upper nozzle on the ejection coefficient.The experimental results show that the self-circulation principle of the new particle impact drill is feasible and the design structure is reasonable.It provides technical support for future field application.