Experiment and Simulation Research on Rock Damage Mechanism in Tooth Indentation

Abstract

In the oil and gas drilling industry, cemented carbide teeth are one of the most widely used rock-breaking elements. In order to reveal the rock damage mechanism of tooth indentation, a series of tooth indentation experiments were conducted in this study, and an indentation simulation was also conducted as a supplement to the experiment. In the experiment, a new method to observe the inner damage status of the rock was put forward, i.e., utilizing the splitting action of the teeth to avoid unexpected rock damage that may affect the actual experiment results. The load-displacement curves and the damage status of the rock revealed that the wedge tooth was more efficient in fracturing and damaging the rock because the load requirement of the wedge tooth was lower, the narrow tooth crown generated larger specific stress in the rock; that rock-breaking advantage of the wedge tooth resulted from the occurrence of the compacted core and the tension stress generated by the core. According to the simulation results, the plastic strain in the intermediate area between the wedge teeth appeared more concentrated and increased faster, and the rock material beneath the wedge teeth was removed earlier than beneath the conical teeth, indicating that wedge teeth, disposed with proper spacing, can break rock more effectively than the conical teeth. The experiment and simulation results in this paper have proved the advantages of the wedge tooth in rock fracturing and damaging, which will provide technical support for the design and development for the drill bits applied in oil and gas drilling.