METHODS AND APPARATUS FOR MECHANICAL AND THERMAL DRILLING
Methods and apparatus for excavation of a borehole in a geological formation are provided. Such methods may include providing a thermal system (54) capable of providing substantially hot fluid, and comprising at least one jet nozzle, providing a mechanical drilling (55) system comprising a drill bit, directing the substantially hot fluid through the jet nozzle (49) towards the geological formation causing an altered portion of geological formation to form, and removing the altered portion using the drill bit, thereby creating cuttings and producing a borehole in the geological formation.