Numerical Simulation of Microwave-Assisted PDC Cutter Breaking Rock Based on PFC

Microwave-assisted rock breaking is a new rock breaking method proposed in recent years. To explore the feasibility of this method in assisting PDC bits to break hard-to-drill formations, a PDC cutter-rock interaction model considering the effects of microwave heating has been developed based on the bond particle model (BPM) built in discrete element software PFC. The effects of different microwave irradiation conditions on the cutting and rock breaking of PDC cutter were studied. The results show that under the same microwave irradiation time and low power, the cutting rock breaking mode is dominated by the extrusion and scraping of PDC cutter. With the increase of microwave power, the thermal cracks in rock gradually increase, and the damage effect of microwave on rock dominates the failure mode of rock in the cutting process. When the microwave loss power reaches 3.51 kW and the irradiation time is 90 seconds, the average cutting force and specific work of rock breaking are 56.77% and 73.9% lower than those of conventional cutting, respectively. The larger the microwave loss power is, the longer the irradiation time is, and the higher the rock breaking efficiency is. Microwave irradiation can reduce the fluctuation of cutting force and make the change of cutting force more gentle, which is helpful to improve the working life of PDC cutter.