| Rock breaking is the core technology of oil and gas drilling engineering.The level of rock breaking efficiency directly determines the speed and cost of oil and gas drilling.Drilling engineering is a part of large investment and high risk in oil and gas reservoir development,and its cost usually accounts for more than 50% of exploration and development costs.With the increasing depth of modern oil and gas exploration and development,the geological conditions are becoming more and more complex,the difficulty of rock breaking is increasing,and the incompatibility of rotating machinery rock breaking drilling technology is becoming increasingly prominent.Rock breaking efficiency is low,drilling speed is slow and cost is high.How to improve the efficiency of rock breaking is an extremely important topic in today’s oil and gas drilling engineering.Therefore,the selection of "Non-transfer Plasma Arc Rock Breaking Technology Research" in this paper has very important theoretical significance and engineering application value.In this paper,according to the specific requirements of plasma arc rock breaking,a non-transferred arc plasma torch is designed.The plasma torch is mainly composed of electrode structure,cooling system,carrier gas channel and insulation structure.Electrode structure design includes structure selection,cathode shape and material,anode structure design,etc.The cooling system consists of a cathode cooling system and an anode cooling system.This design system introduces cooling water into the cathode to achieve cathode cooling,while the anode uses external water cooling.The insulation material of the plasma torch is 3722-phenolic cotton cloth laminated rod,the air flow channel is designed on the middle insulator,and the air intake method is linear air intake.An experimental study on the electric characteristics of the plasma arc was carried out,and the effects and changes of the parameters of the plasma arc on the arc stability and volt-ampere characteristic curve were studied.The effects of gas flow rate,anode diameter and working current on arc voltage and current waveform change characteristics were studied,and the influence mechanism of gas flow and diameter on arc pulsation mode was analyzed.The physical model of plasma arc rock breaking and the mathematical model of the arc temperature and velocity at the nozzle outlet are established,and the temperature field,velocity field and stress field of the rock breaking model are verified by the parameters such as working current,anode diameter and spray distance.Relationship of influence.The effect of plasma arc parameters on the rock breaking ability and the change trend were experimentally studied.The study revealed the influence of gas flow,anode diameter and working current on the breaking speed and the size of the broken channel,as well as rock cooling and rock The influence law of types on plasma arc rock breaking etc.The loss of the cathode and anode during rock breaking was studied and analyzed. |
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