The Study Of One New "Non-contact Rock-breaking" PID Bit And Simulation Of Well Bottom Flow Field

The problem of slow drilling speed and long drilling cycle in deep hard and abrasive formations seriously restricts oil and gas exploitation.Particle impact drilling technology provides technical support for solving this problem.As an important part of particle impact drilling,bit design and optimization and its downhole working environment are particularly important.Aiming at the defects and shortcomings of traditional drill bit,this paper uses the three-dimensional modeling software and foreign particle impact drill bit for reference,uses the method of theoretical analysis and numerical simulation to optimize the design of drill bit,and studies the law of bottom hole flow field.The numerical calculation physical models of nozzles with different structures are established,and the internal and external flow fields of different nozzles are simulated.The results show that the particle impact kinetic energy of streamlined nozzles with 40 mm streamline height,20 mm straight column section and 6.5 mm nozzle diameter decreases slowly,the kinetic energy at the bottom of the impact well is large,and the rock breaking efficiency is high.This nozzle is selected as the nozzle installed by the particle impact drilling bit.?According to the hydraulic structure parameters of the bit,the angle combination of the nozzle and the diameter of the positioning circle are designed,and the parameters are optimized by numerical simulation to ensure the full coverage of the bottom hole.In the aspect of bit structure design,it mainly includes the design of bottom of bit,chip removal groove,layout of diameter-keeping sheet and design of bit inner cavity structure.After checking and optimizing,a new type of "non-contact rock breaking" PID bit is designed.Using the method of controlling variables and FLUENT numerical simulation to study the bottom hole flow field shape,the results show that when the particle diameter is 1.7 mm,the particle volume fraction is 3%,the spray distance is 52 mm,and the bit speed is 90 rpm,the bottom hole swirl is less,the particle kinetic energy loss is smaller,the particle breaking efficiency is better,and the particle retention time at the bottom of the well is short,and the particle can quickly return to the surface device.It provides theoretical basis for laboratory and field experiments of particle impact drilling.