Patent ID: 6412579
Filing Date: 2002-07-02
Classification: E21B

Abstract:
A two stage bit enabling enhanced penetration rates comprising:a body defining a proximal end adapted for connection to a drilling string and a distal end, where said distal end defines a pilot and an intermediate reamer section; where said pilot includes a first cutter face defining a given diameter D; where said reamer section includes a second cutter face defining a given diameter R where R>D; where the first cutter face includes upsets where each upset defines an upper and a lower portion where said upper portion is provided with a series of cutting elements and said lower portion is provided with a surface adapted to extend to gauge into substantially non-cutting contact with the formation; where the second cutter face includes upsets which extend substantially to gauge and which extend over 180Â° of the rotational circumference of said reamer where said upsets define an upper and a lower portion where said upper portion is provided with a series of cutting elements; and where the upsets formed on the pilot section are misaligned relative to the upsets formed on the reamer section.