Rotary drill bits
First Claim
1. A rotary drill bit for drilling holes in subsurface formations, the bit having a central axis of rotation and comprising a bit body having a shank for connection to a drill string, a plurality of circumferentially spaced blades on the bit body extending outwardly away from said central axis of rotation of the bit, and a plurality of cutters mounted along each blade, at least a majority of which cutters are each located at a different distance from the bit axis than any other cutter, said cutters including primary cutters having cutting edges which define a primary cutting profile and secondary cutters having cutting edges which define a secondary cutting profile which is disposed inwardly of the primary cutting profile with respect to the bit body wherein the primary cutters are mounted on primary blades and at least some of the secondary cutters are mounted on separate secondary blades and there are fewer secondary cutters on each secondary blade than there are primary cutters on each primary blade.
2 Assignments
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Accused Products
Abstract
A rotary drill bit, for drilling holes in subsurface formations, comprises a bit body having a shank for connection to a drill string, a number of circumferentially spaced blades on the bit body extending outwardly away from the central axis of rotation of the bit, and a number of cutters mounted side-by-side along the leading edge of each blade. The cutters include primary cutters having cutting edges which define a primary cutting profile and secondary cutters having cutting edges which define a secondary cutting profile which is disposed inwardly of the primary cutting profile with respect to the bit body. The secondary cutters may be on different blades from the primary cutters, or may be mounted on the same blades, rearwardly of the primary cutters. At least the majority of the cutters are located at different distances away from the bit axis, so that as the bit rotates each secondary cutter follows a path which lies intermediate the paths followed by two primary cutters.
96 Citations
54 Claims
- 1. A rotary drill bit for drilling holes in subsurface formations, the bit having a central axis of rotation and comprising a bit body having a shank for connection to a drill string, a plurality of circumferentially spaced blades on the bit body extending outwardly away from said central axis of rotation of the bit, and a plurality of cutters mounted along each blade, at least a majority of which cutters are each located at a different distance from the bit axis than any other cutter, said cutters including primary cutters having cutting edges which define a primary cutting profile and secondary cutters having cutting edges which define a secondary cutting profile which is disposed inwardly of the primary cutting profile with respect to the bit body wherein the primary cutters are mounted on primary blades and at least some of the secondary cutters are mounted on separate secondary blades and there are fewer secondary cutters on each secondary blade than there are primary cutters on each primary blade.
- 20. A rotary drill bit for drilling holes in subsurface formations, the bit having a central axis of rotation and comprising a bit body having a shank for connection to a drill string, a plurality of circumferentially spaced blades on the bit body extending outwardly away from said central axis of rotation of the bit, and a plurality of cutters mounted along each blade, at least a majority of which cutters are each located at a different distance from the bit axis than any other cutter, said cutters including primary cutters having cutting edges which define a primary cutting profile and secondary cutters having cutting edges which define a secondary cutting profile which is disposed inwardly of the primary cutting profile with respect to the bit body wherein the primary cutters are mounted on primary blades and at least some of the secondary cutters are mounted on separate secondary blades, the primary blades are longer than the secondary blades so as to extend into said central region of the bit body.
- 39. A rotary drill bit for drilling holes in subsurface formations, the bit having a central axis of rotation and comprising a bit body having a shank for connection to a drill string, a plurality of circumferentially spaced blades on the bit body extending outwardly away from said central axis of rotation of the bit, and a plurality of cutters mounted along each blade, at least a majority of which cutters are each located at a different distance from the bit axis than any other cutter, said cutters including primary cutters having cutting edges which define a primary cutting profile and secondary cutters having cutting edges which define a secondary cutting profile which is disposed inwardly of the primary cutting profile with respect to the bit body wherein the secondary cutters are of different sizes.
- 45. A rotary drill bit for drilling holes in subsurface formations, the bit having a central axis of rotation and comprising a bit body having a shank for connection to a drill string, a plurality of circumferentially spaced blades on the bit body extending outwardly away from said central axis of rotation of the bit, and a plurality of cutters mounted along each blade, at least a majority of which cutters are each located at a different distance from the bit axis than any other cutter, said cutters including primary cutters having cutting edges which define a primary cutting profile and secondary cutters having cutting edges which define a secondary cutting profile which is disposed inwardly of the primary cutting profile with respect to the bit body wherein the secondary cutters are of different size and larger secondary cutters are arranged alternately with smaller secondary cutters longitudinally of a blade.
- 51. A rotary drill bit for drilling holes in subsurface formations, the bit having a central axis of rotation and comprising a bit body having a shank for connection to a drill string, a plurality of circumferentially spaced blades on the bit body extending outwardly away from said central axis of rotation of the bit, and a plurality of cutters mounted along each blade, at least a majority of which cutters are each located at a different distance from the bit axis than any other cutter, said cutters including primary cutters having cutting edges which define a primary cutting profile and secondary cutters having cutting edges which define a secondary cutting profile which is disposed inwardly of the primary cutting profile with respect to the bit body wherein the primary cutting profile is a distance from the secondary cutting profile which increases with distance from the axis of rotation of the bit.
- 53. A rotary drill bit for drilling holes in subsurface formations, the bit having a central axis of rotation and comprising a bit body having a shank for connection to a drill string, a plurality of circumferentially spaced blades on the bit body extending outwardly away from said central axis of rotation of the bit, and a plurality of cutters mounted along each blade, at least a majority of which cutters are each located at a different distance from the bit axis than any other cutter, said cutters including primary cutters having cutting edges which define a primary cutting profile and secondary cutters having cutting edges which define a secondary cutting profile which is disposed inwardly of the primary cutting profile with respect to the bit body wherein the primary cutting profile is a distance from the secondary cutting profile which decreases with distance from the axis of rotation of the bit.
Specification