Patent ID: 6142247
Filing Date: 2000-11-07
Classification: E21B

Abstract:
An earth boring bit comprising:a bit body adapted for attachment to a drill string;at least one bearing shaft extending downwardly from the body;a cutter rotatably secured to said bearing shaft, including teeth with exposed ends composed at least partially of wear resistant material and having a selected projection from the surface of the cutter to form cuttings from the borehole bottom, each cutter having a backface, a gage area adjacent the backface, and a heel area inward of the gage area;a nozzle retained in the body, including an orifice to discharge a jet stream of fluid having a high velocity core, the high velocity core being directed within a space bounded by the backface of the cutter, bit body, borehole wall and a radial plane tangent to the tips of the teeth in the heel area at their outermost sweep during rotation away from the borehole bottom;whereby the high velocity jet is biased towards the heel and gage area of the cutter to dislodge cuttings from the cutter as well as the borehole bottom.