A slurry jet driller is a novel drilling method, which delivers an abrasive slurry and supercritical gas mixture, to an expander nozzle. The expanded fluids flowing out of the nozzle, energize the particles, which hit the target material and erode it, achieving drilling. The expansion of the gas from a super critical state to in situ pressure and temperature conditions is the driving mechanism of the drilling operation. The primary objective of this paper is to evaluate the feasibility of the novel slurry jet drilling system. An experimental program is carried out for testing the performance of a slurry jet driller. The slurry is formed by mixing water with garnet particles, and a super critical carbon dioxide as the gas phase. The purpose of experiments is to evaluate the erosive nature of garnet rocks and to test the cutting efficiency of the nozzle. The acquired data show that the material removal rate increases with increase in the gas-slurry flow ratio, until a ratio of 1.5. A further increase in the flow ratio results in a reduction of the rate of material removal. Improved nozzle geometry was obtained using a program written in MATLAB. Criteria used for geometry improvement was the force applied to the bottom of the drilled bore. A rudimentary model is developed for the prediction of material removal rate utilizing a slurry jet driller, which is presented in a dimensionless form. The model incorporates the important variables affecting the jet driller system performance, including fluid and target material properties, and particle velocity. A fair agreement is observed between model predictions and experimental data, exhibiting a 20% deviation.
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