Numerical study on the effect of confinement on thermal spallation drilling of hard rock

Abstract

This paper presents a numerical study on the effect of confining pressure (down-to-hole pressure) on the performance of the thermal jet drilling on rock. For this end, a numerical method including a viscoplastic-damage model for rock and an explicit scheme for solving the governing thermo-mechanical problem, which is assumed uncoupled. Moreover, rock heterogeneity, which facilitates the thermal spallation phenomenon, is taken into account. Numerical simulations under axisymmetric conditions demonstrate that the efficiency of thermal spallation based drilling is reduces drastically due to confinement.