Patent ID: 7775302
Filing Date: 2010-08-17
Classification: E21B

Abstract:
1. An earth boring bit assembly for casing-while-drilling, comprising: a casing shoe adapted to be secured to a lower end of a string of casing, the casing shoe having a plurality of stabilizer blades spaced circumferentially apart from each other, defining a recessed flute between each of the blades; each of the blades having a leading edge and a trailing edge considering a direction of rotation of the casing shoe; a cutter arm seat formed on the leading edge of each blade at a lower end of the casing shoe; a tubular mandrel having an upper portion carried within the casing shoe and a threaded lower end below the casing shoe for threaded engagement with a pilot bit; a plurality of cutter arms pivotally mounted to the mandrel and movable from an extended position located within one of the cutter arm seats to a recessed position, each of the cutter arms having a plurality of cutting elements mounted on a leading side of the cutter arm; and each of the flutes defining an opening at and extending forward from the cutting elements so as to reduce accumulation of cuttings in front of the cutting elements.