Research progress and prospects on working characteristics and failure mechanisms of diamond drill bits under extreme environments in deep drilling

Abstract:

The working performance of diamond drill bits faces severe challenges under extreme deep-drilling environments characterized by high temperature， high pressure， high abrasiveness， strong corrosion， and multi-field coupling. This paper systematically reviews the working characteristics and failure mechanisms of PDC bits and impregnated diamond bits under the aforementioned environments. The results indicate that： under high-temperature conditions， PDC bits primarily suffer from thermal damage and interfacial delamination， while impregnated bits exhibit matrix softening and thermal damage to diamond； under high-pressure conditions， PDC bits are prone to cutter fracture and delamination， whereas impregnated bits undergo matrix deformation and diamond particle shedding； under highly abrasive conditions， both types of bits experience synergistic failure caused by abrasive wear and vibration fatigue； under corrosive conditions， PDC bits undergo chemical dissolution and micro-galvanic corrosion， whereas impregnated bits mainly exhibit selective dissolution of the binder phase， and the corrosion-wear synergy significantly accelerates material loss； multi-field coupling promotes mutual reinforcement among various damage mechanisms， producing a nonlinear amplification effect. Correspondingly， the service life of drill bits can be extended or the rock-breaking efficiency can be improved through hydraulic structure optimization and heat-resistant material modification， shaped cutters with jet assistance， bionic structures and ultra-wear-resistant matrices， composition optimization and surface coating， as well as gradient structure design. Future research should focus on deepening the research on multi-field coupling mechanisms， promoting the engineering validation of extreme-environment-specific materials， and developing intelligent drill bit technologies， thereby supporting the iterative upgrades of drilling technologies for extreme deep-earth environments.