The fragmentation mechanism of granite in electrical breakdown process of plasma channel drilling

Abstract Low rate of penetration (ROP) and high drilling cost are the key problems that encountered in hot dry rock (HDR) geothermal resources exploitation utilization. Plasma channel (PCD) is a potential technology which has advantages rock-breaking efficiency ROP. A detailed understanding PCD essential to optimize electrical parameters bit structure. Therefore, this paper uses probabilistic evolution model thermo-mechanical coupling PFC2D reveal generation plasma trajectory cracks heterogeneous granite under high-voltage electric pulse. The results show increasing temperature on will not alter trend initiation propagation cracks, but simply reduces time consumption crack initiation. quantity intragranular shear always largest, they mainly distributed around channel. In addition, compared with channels formed when complete breakdown occurs, maximum depth partial larger same electrode gap. This study also includes an experimental program examine fragmentation borehole caused by bit. research can provide new ideas methods for improving HDR formation, help design structural drill bits based technology.