基于响应面法的仿生PDC钻头水力结构优化设计

Optimization Design of Bionic PDC Bit Hydraulic Structure Based on Response Surface Method

合理的钻头水力结构能避免泥包现象发生,提升钻井效率。为完善仿生PDC钻头的水力结构,基于κ-ε湍流模型和离散相模型对4种不同水力结构方案进行数值计算,确定了最佳方案为喷嘴和辅助喷嘴结合。为确定该方案下最佳结构参数,使用响应面法建立了以喷嘴直径x_(1),辅助喷嘴直径x_(2)、喷嘴距钻头中心径向距离x_(3)为设计变量,采样点最大速度D和采样点平均速度E为目标函数的数学模型,基于回归分析对钻头水力结构进行优化设计,求出最佳参数为喷嘴直径16.36 mm,辅助喷嘴直径8 mm,喷嘴距钻头中心径向距离63.85 mm,并对该参数下的水力结构性能进行了数值计算。结果表明:优化后的钻头水力结构不仅减少了流体井底速度波动次数,且明显提升了整体速度,解决了原有的涡流现象,增强了钻井液携岩性能,减小了粒子浓度。

Reasonable bit hydraulic structure can avoid mud bag phenomenon and improve drilling efficiency.In order to improve the hydraulic structure of bionic PDC bit,four different hydraulic structure schemes were numerically calculated based onκ-εturbulence model and discrete phase model.The best scheme was the combination of nozzle and auxiliary nozzle.In order to determine the optimal structural parameters under this scheme,a mathematical model with nozzle diameter x_(1),auxiliary nozzle diameter x_(2),radial distance from nozzle to drill center x_(3),maximum velocity of sampling point D and average velocity of sampling point E as objective functions was established by response surface method.Based on regression analysis,the hydraulic structure of drill bit was optimized.The optimal parameters were obtained as follows:nozzle diameter 16.36 mm,auxiliary nozzle diameter 8 mm,radial distance from nozzle to drill center 63.85 mm,and the hydraulic structure under this parameter was numerically calculated.The results show that the optimized hydraulic structure of the drill bit not only reduces the number of bottom hole velocity fluctuations,but also significantly improves the overall velocity,solves the original eddy current phenomenon,enhances the rock carrying performance of the drilling fluid and reducing the particle concentration.