Abstract: A drill tool comprising a drill pipe having a turbine and a hydraulic pump, wherein drilling fluid is passed through the turbine and into the hydraulic pump through a hollow shaft in the drill pipe. The drill tool also includes a high pressure jet at a distal end of the drill pipe for discharging drill fluid at a pressure which is between 20 and 40 MPa greater than the ambient pressure of the drill hole.

Abstract: A boring bit for drilling is provided comprising one set of rotatable toothed wheels secured thereon as well as one set of tubular nozzles and one central nozzle for injecting drilling fluid from a chamber in bit body toward the bottom of a borehole. The boring bit comprises the inlet end of said tubular nozzle being secured on the bit body and connected with said chamber while its outlet end is quite close during operation to the lowest point of toothed wheels and the bottom of a borehole, and the fluid passage of said tubular nozzle from the inlet end to the outlet end is straight and cylindrical. Branch fluid passages are provided on the main fluid passage of said central nozzle for washing and cooling toothed wheels.