Patent ID: 7520343
Filing Date: 2009-04-21
Classification: E21B

Abstract:
1. A borehole drilling tool, comprising: a drill shoe having a cylindrical sidewall, a bore and a threaded upper end for connection to a string of casing; a plurality of cutting elements positioned at a lower end of the drill shoe; a retrievable tubular member that lands in the drill shoe, the tubular member having a threaded lower end that extends below the cutting elements when landed for connection to a drill bit, the tubular member having a cylindrical sidewall and an axially extending passage that has an upper end in communication with the bore of the drill shoe for receiving drilling fluid pumped down the string of casing; and a plurality of cutting element ports extending through the sidewall of the tubular member, the cutting element ports having inlets at the bore of the tubular member and outlets on the exterior of the tubular member, the outlets being located below the lower end of the drill shoe when the tubular member has landed in the drill shoe, the cutting element ports being directed laterally outward toward at least part of the cutting elements for discharging drilling fluid onto said at last part of the cutting elements.