Study on reverse circulation structural parameters of through-type ring jet DTH bit

Abstract:

Reverse circulation drilling technology， as an advanced drilling method， has attracted significant attention due to its remarkable advantages in improving drilling efficiency and reducing environmental pollution. Further optimizing the structural design of reverse circulation drill bits to enhance their performance remains a key research focus. This study focuses on the reverse circulation structure of the through-type ring jet DTH （Down-the-Hole） bit. Through systematic numerical simulation and experimental research， the influence laws of structural parameters on reverse circulation performance are explored in depth.Based on EFD （Engineering Fluid Dynamics） technology and using an L₂₇（313） orthogonal experimental design， numerical simulations were conducted to analyze the impact of 11 key structural parameters on reverse circulation performance. The results indicate that nozzle diameter， the distance between the nozzle and the inlet of the bottom jet hole， and the inlet air volume are the most significant factors affecting reverse circulation performance. The experimental findings show that a smaller nozzle diameter， an increased number of inner jet layers， and an inlet air volume within the range of 4~4.5m3/min can significantly enhance reverse circulation performance. Moreover， the open-jet design of the ring-jet reverse circulation structure can effectively suppress bit balling， especially in clay layers and other strata prone to bit balling.This study not only provides theoretical and technical support for the design of ring-jet reverse circulation drill bits but also lays the foundation for optimizing drilling process parameters and improving drilling efficiency.