Design And Optimization For The Self-oscillating Rotary Percussive Drilling Tool

Aiming at the problems of low drilling penetration rate and high drilling cost in deep hard formations,efficient rock breaking drilling method suitable for deep well and hard formation is one of the important development directions for deep well drilling.Integrated the advantages of vibration-drilling and hydraulic pulse,the self-oscilation rotary percussive drilling tool can get a favorable speed-increasing effection.In order to further improve the efficiency,proposed a new design scheme of the multi-stage piston self-oscilation rotary percussive drilling tool,so as to provide a more effective technical method for the increase of drilling penetration rate in deep well and hard formation.First,combined with the modulation principle of the self-oscillating rotary percussion drilling tool,through explicit dynamic simulation,studied the rock broken rules of PDC teeth under rotary percussive loadings,and analyzed the influence rules of impact force amplitude and impact frequency on rock breaking efficiency.The results show that it is more practical to use the impact amplitude as the criterion for structural optimization design of the self-oscillating rotary percussion drilling tool.Secondly,in order to improve the impact force amplitude,proposed the design scheme of the multi-piston self-oscillating rotary percussive drilling tool,and verified the feasibility of the design scheme by the large eddy simulation method,explored the influence law of multipiston on the tool performance,the research results show that with the increase of multi-piston,the tool impact force amplitude increases significantly,impact frequency decreases gradually,pressure loss gradually increases.Combined with the requirement of pressure loss in the field application,the four-piston self-oscillating rotary percussive drilling tool can achieve greater impact force amplitude under the pressure loss condition.Then,analyzed the influence of flow and structural parameters on the performance of the four-piston self-oscillating rotary percussive drilling tool by the large eddy simulation method,determined the recommended flow and the structure proportion.On this basis,combined with the large eddy simulation and orthogonal test design method with impact force amplitude as the optimum criterion,completed the design and optimization for the four-piston self-oscillating rotary impact drilling tool,the research results can provide data support for the development of the engineering prototype.At last,developed the four-piston self-oscillating rotary percussive drilling tool and conducted the field test.The experimental results show that the tool has significant speed increase effect and good reliability.In this paper,through numerical simulation and field experiments,proved that the multipiston self-oscillating rotary percussive drilling tool is feasible and can further improve the tool efficiency,which can provide us a more effective technical mean for improving the drilling efficiency in deep hard formation.