Innovation and Application of Cluster Edge Teeth of DTH Hammer Drill Bit in Large Diameter Geothermal Well with High Strength Rock

Down the Hole (DTH) Hammer drilling has high rock breaking efficiency and strong advantage in hard rock drilling, which can reduce the cost of geothermal drilling. However, when the drill bit rotation speed and the DTH percussion frequency do not match properly, specially when the drill bit diameter is large and the ball tooth diameter is small, while drilling high strength formation, the edge teeth of the drill bit are prone to fracture and break, leading to the failure of the drill bit and a significant reduction in its lifespan.This paper investigates the failure modes firstly, then analyzes the failure mechanism of large diameter DTH bit, and proposes a novel method of cluster edge teeth of DTH hammer drill bit in large diameter geothermal well with high strength rock. The drill bits of this innovative design have been mass-produced. Widespread field applications have shown significant improvements in drill bit life and drilling efficiency, obtaining the reduction of drilling costs.