Numerical simulation of rock-breaking characteristics of tri-cone bit in hard formations

Abstract:

To address the engineering challenges of frequent failure and short service life of roller cone bits in hard formation drilling， this study established a nonlinear contact dynamic model between the bit and rock based on field drilling data. The Drucker-Prager criterion was adopted to describe the elastoplastic behavior of the rock. The rock-breaking process of a tri-cone bit under the coupled effects of weight on bit （WOB） and rotary speed was simulated using the finite element software ABAQUS. The results indicate that rock breakage is primarily achieved through impact and shear， with the induced tensile stress being the dominant factor in rock failure. Pronounced longitudinal and torsional vibrations occur during the rock-breaking process， and the resulting transient impacts are the root cause of accelerated tooth wear and bearing failure. This conclusion is consistent with field failure cases. The research reveals the failure mechanism of roller cone bits in hard formations and proposes recommendations such as preferentially selecting wear-resistant bits， installing shock absorbers， and optimizing drilling parameters. These findings provide important theoretical guidance and practical value for enhancing drilling efficiency in deep hard formations and reducing engineering costs.