Drill bit with performance-improving cutting structure
AssigneeSmith International, Inc.
InventorsGraham Mensa-Wilmot, Carl W. Keith
Life of this patent
Estimating the term…
Abstract
A fixed cutter drill bit includes sets of cutter elements mounted on the bit face. Each set includes at least two cutters mounted on different blades at generally the same radial position with reset to the bit axis but having differing degrees of backrake. The cutter elements of a set may be mounted having their cutting faces out-of-profile, such that certain elements in the set are exposed to the formation material to a greater extent than other cutter elements in the same set. The cutter elements in a set may have cutting faces and profiles that are identical, or they may vary in size or shape or both. The bit exhibits increased stability and provides substantial improvement in ROP without requiting excessive WOB.
Claims43
A cutting structure of a drill bit for cutting kerfs in formation material when the bit is rotated about its axis, said cutting structure comprising:
- a set of spaced cutter elements mounted on the bit at substantially the same radial position relative to the bit axis such that each of said cutter elements in said set cuts in substantially the same kerf as the other cutter elements in said set when the bit is rotated about its axis;
- and
- wherein at least one of said cutter elements in said set is mounted with a backrake angle that differs from the backrake angle of other elements in said set.
A drill bit for drilling through formation material when said bit is rotated about its axis, said bit comprising:
- a bit body;
- a bit face on said body;
- at least one set of cutter elements disposed on said bit face, said cutter element set including a first cutter element mounted at a first backrake angle and a second cutter element mounted at a second backrake angle that differs from said first backrake angle;
- and
- wherein said first and second cutter elements of said set are mounted in said bit face at generally common radial positions relative to the bit axis.
A fixed cutter drill bit for drilling through formation material when said bit is rotated about its axis, said bit comprising:
- a bit body;
- a bit face on said body, said bit face including a plurality of cutter elements mounted thereon and protruding therefrom, said cutter elements having cutting faces for cutting swaths through the formation material and being arranged in a plurality of cutter sets radially spaced from each other relative to the bit axis;
- wherein said cutter sets comprise a plurality of angularly spaced cutter elements having element axes at generally common radial positions relative to the bit axis;
- and
- wherein said cutter elements of said sets are mounted on said bit face at varying backrake angles.
A fixed cutter drill bit for drilling through formation material when said bit is rotated about its axis, said drill bit comprising:
- a bit body including a bit face having at least one pair of radially disposed blades, each blade pair including a first blade and a second blade angularly spaced from said first blade;
- cutter elements disposed in rows on said blades, each of said rows including cutter elements radially spaced from each other relative to the bit axis, said cutter elements in said rows having cutting faces for cutting formation material and an element axis that is normal to said bit face;
- wherein said cutter elements in said rows are arranged in sets, each of said sets comprising a first cutter element on said first blade and a second cutter element on said second blade having element axes at generally common radial positions relative to the bit axis;
- and
- wherein said first cutter element is mounted at a first backrake angle and said second cutter element is mounted at a second backrake angle that is different from said first backrake angle.
Dependencies are inferred from the claim text.