Development and application of φ73 mm high toughness and high strength drilling pipe

According to the failure such as fracture, bending and thread gluing while drilling large diameter and directional long borehole using conventional drill rod, the paper designed a new drill rod named φ73 mm high toughness and high strength drilling pipe(HHDP) by analyzing the failure reason, optimizing joint structure and selecting materials. Performance testing and field testing results show that HHDP has antitorque capacity of 20 kN·m and flexural capacity of 2°/3 m, its accident rate is about 0.26 time/km while drilling large diameter and directional borehole, about 18% of the other drilling pipe under same drilling condition.