| Abstract |
To make geothermal energy more widely available at an acceptable cost per kWh for the end user, basement rock needs to be drilled at a higher rate of penetration and longer bit runs. Thermo-mechanical coupling at the bit-rock interface plays a critical role in determining drilling performance, particularly in high-temperature geothermal environments. This work explores the feasibility of shock cooling, defined as the rapid quenching of hot rock by cold fluid, as a mechanism for altering rock failure behavior and reducing the mechanical specific energy (MSE) during cutting. A fully coupled thermo-mechanical finite element model was developed using the Abaqus software under a dynamic explicit framework to simulate the interaction between a polycrystalline diamond compact (PDC) cutter and heterogeneous granite in the presence of a cooling fluid. The simulation setup includes dynamic heat transfer, thermal front propagation, and damage-based element deletion to capture progressive rock removal. Rock heterogeneity and temperature-dependent material behavior were included through custom input routines and parametric variations. The modeling approach enables evaluation of drilling parameters such as cutter speed, depth of cut, and fluid-rock interaction. The work highlights the importance of thermal propagation relative to cutter engagement. Specifically, the model captures when thermal front propagation becomes less beneficial at high rates of penetration in drilling, if the thermal front depth is significantly shallower than the cutting depth. This study provides a numerical framework for assessing thermally assisted drilling concepts, with potential applications in improving the efficiency and durability of geothermal well construction operations. |