High-Pressure Jet-Drilling Experiments in Some Hard Rocks

Abstract

The potential penetration rates of high-pressure jet bits drilling in hard rocks have been investigated experimentally. It has been found that the rates of penetration are much lower in hard, impermeable rock than in permeable rock [1]. Test results indicate that a laminated rock (Martelange schist) cannot be cut by jets at a high rate, which calls for hybrid bits. Isotropic rock can be jet-drilled at higher than conventional drilling rates, which may become profitable at daily rig costs in excess of approximately $20,000.