Hydraulic Structure Design Of Rotary Cutting PDC Bit

In recent years,shale gas has attracted wide attention as a new type of clean energy.However,in the process of shale gas exploitation,there are some problems,such as low rock breaking efficiency,poor rock carrying effect and obvious mud inclusion,which lead to the prolongation of drilling cycle and the increase of engineering cost.As a new type of PDC bit,rotary cutting PDC bit has provided a new solution for solving the problems encountered in the process of shale gas exploitation.In this paper,the research methods and research status of hydraulic structure of conventional PDC bits are investigated.The standard k-epsilon model and discrete phase model(DPM)are used to analyze the original bottom hole flow field model of rotary cutting PDC bits.The hydraulic structure of rotary cutting PDC bits is improved according to the simulation results.The bottom hole flow field of the improved bit is analyzed by numerical simulation method.The analysis results show that: the change of cutter head shape is beneficial to the flow of workflow and can reduce the mass concentration of cuttings near the cutter head.The use of nozzles with curvature can improve the bottom hole cleaning effect in the cutter head area of rotary PDC bit.When the nozzle with a curvature of 1/50 is used,the bottom hole cleaning effect in the cutter head area is the best.Through the analysis of the influence of the combination of the central and edge nozzle diameters on the bottom hole flow field,when the diameter of the central nozzle is 12 mm and the diameter of the edge nozzle is 8.8 mm,the cleaning effect of the bottom hole area of the bit is most obvious.According to the above analysis,this paper has reference significance for the optimization design of hydraulic structure of rotary PDC bit and the application of rotary PDC bit in practical engineering.