Patent ID: 7083011
Filing Date: 2006-08-01
Classification: E21B

Abstract:
1. A fluid drilling head of the type having a plurality of nozzles in a rotatable nozzle assembly, said nozzles being adapted to be supplied with high pressure fluid forming jets positioned to cut adjacent rock and angled to provide a reactive force arranged to rotate the nozzle assembly, the head being provided with a gauging ring concentrically located relative to the rotatable nozzle assembly and positioned behind the jets relative to the direction of advance of the drilling head, the gauging ring having an overall circumference sized to fit within the desired section of the bore being drilled by the drilling head, the gauging ring being generally cylindrical in configuration and having a radial, annular clearance to the rotatable nozzle assembly, the clearance being sized to permit the flow of rock particles eroded by the cutting action of the fluid jets between the gauging ring and the rotatable nozzle assembly.