Development And Application Of PDC Bit Bottom Flow Field Simulation Platform

PDC drill bit is a main tool of drilling rock,whose hydraulic structure directly affects the cuttings removal and bit cooling effect.To improve the hydraulic structure in a timely manner,the bottom hole flow field of PDC drill bit has been studied with numerical simulation to investigate the disadvantage of the hydraulic structure.However,the existing software numerical simulation method has some disadvantages,such as the high threshold,tedious operation process,repetitive labor and low analysis efficiency.What's more,the performance evaluation criteria of the hydraulic structure still exists inadequacies.Because of these considerations,this paper introduces some new evaluation criteria and researches the integration and exploitation of the PDC drill bit bottom hole flow field numerical simulation technology.Based on the existing simulation technique this paper has studied the following aspects:(1)The cooling effect of the PDC drill bit cutters.Based on the study of the temperature distribution and thermal wear mechanism of PDC drill bit cutters,the heating and heat transfer model of cutters were simplified.And in the numerical simulation analysis process the effect of bottom hole flow field on the cutting heat of cutters was considered to directly take the cutters surface temperature as an evaluation criteria of cooling effect of cutters.(2)The integration of simulation technology about the PDC bit bottom hole flow field.According to different drilling technology,this paper improved the simulation technology of single-phase flow,gas-liquid two phase flow,liquid-solid two phase flow and gas-liquid-solid three phase flow,and further perfected the evaluation method of cuttings removal and cooling effectiveness.What's more,the simulation technology was programmed which includes the grid division,computational fluid dynamics(CFD)pre-processing,CFD solver solving and CFD post-processing.The simulation technology was then encapsulated by EASA commercial packaging software to ultimately establish a PDC bit bottom hole flow field simulation platform based on Web services.(3)The application of the PDC drill bit bottom hole flow field simulation platform.Based on the simulation platform,this paper researched the effect of the junk slot shape on the cuttings removal and cooling effect.And,the research and application of the hydraulic structure of a suction micro coring PDC drill bit,shows that the coring effect and drilling efficiency of the optimizing bit is well.A large number of applications show that the PDC drill bit bottom hole flow field simulation platform developed in this paper simplifies the complex operation process of traditional numerical simulation analysis,improves the analysis efficiency,and reduces the cost of manpower and material resources.This simulation platform is suitable for the conventional PDC drill bit and personalized PDC drill bit,and has strong engineering practical value.