A drill bit for drilling a borehole in an earthen formation has a central axis and a cutting direction of rotation. The bit includes a bit body configured to rotate about the axis in the cutting direction of rotation. The bit body includes a bit face. The bit also includes a blade extending radially along the bit face. In addition, the bit includes a first cutter element mounted to a cutter-supporting surface of the blade and a second cutter element mounted to the cutter-supporting surface of the blade. The first cutter element has a central axis and includes a first forward-facing cutting face including a first cutting tip distal the cutter supporting surface and a first planar surface extending radially from the first cutting tip toward the central axis of the first cutter element. The first planar surface is oriented at a first effective backrake angle measured between the cutter supporting surface and a surface vector of the first planar surface. The second cutter element has a central axis and comprises a second forward-facing cutting face including a second cutting tip distal the cutter supporting surface and a second planar surface extending radially from the second cutting tip toward the central axis of the second cutter element. The second planar surface is oriented at a second effective backrake angle measured between the cutter supporting surface and a surface vector of the second planar surface. The second effective backrake angle is greater than the first effective backrake angle.

A drill bit for drilling a borehole in an earthen formation has a central axis and a cutting direction of rotation. The bit includes a bit body configured to rotate about the axis in the cutting direction of rotation. The bit body includes a bit face. The bit also includes a blade extending radially along the bit face. In addition, the bit includes a first cutter element mounted to a cutter-supporting surface of the blade and a second cutter element mounted to the cutter-supporting surface of the blade. The first cutter element has a central axis and includes a first forward-facing cutting face including a first cutting tip distal the cutter supporting surface and a first planar surface extending radially from the first cutting tip toward the central axis of the first cutter element. The first planar surface is oriented at a first effective backrake angle measured between the cutter supporting surface and a surface vector of the first planar surface. The second cutter element has a central axis and comprises a second forward-facing cutting face including a second cutting tip distal the cutter supporting surface and a second planar surface extending radially from the second cutting tip toward the central axis of the second cutter element. The second planar surface is oriented at a second effective backrake angle measured between the cutter supporting surface and a surface vector of the second planar surface. The second effective backrake angle is greater than the first effective backrake angle.

The invention relates to reamers used in downhole oil well drilling operations, particularly in reaming while drilling applications. Presented is a reamer having an interior channel which runs along an elongate axis of the entire body of the reamer, wherein there are openings along both ends of the reamer, exposing the interior channel. Additionally presented in the reamer are a plurality of paths extending parallel to the interior channel along the exterior of the body of the reamer, and running in a helical pattern along the entirety of the exterior of the body of the reamer. Disposed within the helical paths are a plurality of cutting inserts, which cutting inserts are enabled to provides a uniform cutting surface against a well bore, which preferably improves cutting action and reduces strain on the reamer.

A method for forming localized binder in a drilling tool is disclosed. A method includes placing a reinforcement material in a matrix bit body mold, placing a localized binder material within the reinforcement material at a selected location in the matrix bit body mold, wherein the localized binder material confers a selected physical property at the selected location, placing a universal binder material in the matrix bit body mold on top of the reinforcement material, heating the matrix bit body mold, the reinforcement material, the localized binder material, and the universal binder material to a temperature above the melting point of the universal binder material, infiltrating the reinforcement material and the localized binder material with the universal binder material, and cooling the matrix bit body mold, the reinforcement material, the localized binder material, and the universal binder material to form a matrix drill bit body.

A cutting tool includes a body configured to rotate about a longitudinal axis, a blade connected to the body, and a pre-formed segment. The blade extends away from the body and includes a recess formed in a leading face of the blade. The pre-formed segment is disposed in the recess adjacent to the leading face of the blade. The pre-formed segment is connected to the blade. The pre-formed segment includes a cutter pocket therein, the cutter pocket having a sidewall and a base.

Methods and systems for receiving an earth-boring tool design, identifying a force model equation to utilize in simulating performance of the earth-boring tool design within a planned drilling operation, simulating performance of the earth-boring tool design within the planned drilling operation utilizing the identified force model equation, and based at least partially on the simulated performance of the earth-boring tool, estimating a probability of an actual earth-boring tool experiencing stick-slip within the planned drilling operation.

Methods and systems for receiving an earth-boring tool design, identifying a force model equation to utilize in simulating performance of the earth-boring tool design within a planned drilling operation, simulating performance of the earth-boring tool design within the planned drilling operation utilizing the identified force model equation, and based at least partially on the simulated performance of the earth-boring tool, estimating a probability of an actual earth-boring tool experiencing stick-slip within the planned drilling operation.

Provided is a mill bit and well system. The mill bit, in one aspect, includes a tubular having an uphole end and a downhole end. The mill bit, in accordance with this aspect, further includes a first cutting section having one or more first cutting surfaces disposed about the tubular, the first cutting section having a first material removal rate and configured to engage with wellbore casing disposed within a wellbore. The mill bit, in accordance with this disclosure, further includes a second cutting section having one or more second cutting surfaces disposed about the tubular, the second cutting section having a second material removal rate less than the first material removal rate and configured to engage with a whipstock disposed within the wellbore.

Provided is a mill bit and well system. The mill bit, in one aspect, includes a tubular having an uphole end and a downhole end. The mill bit, in accordance with this aspect, further includes a first cutting section having one or more first cutting surfaces disposed about the tubular, the first cutting section having a first material removal rate and configured to engage with wellbore casing disposed within a wellbore. The mill bit, in accordance with this disclosure, further includes a second cutting section having one or more second cutting surfaces disposed about the tubular, the second cutting section having a second material removal rate less than the first material removal rate and configured to engage with a whipstock disposed within the wellbore.

A multi-impeller passive-rotating-stirring-type rotary drilling rig for open caissons includes a hollow main drill pipe, a drill bit, four cutting edges, four impeller shafts, four passive impellers and a rotation bracket. Through being uniformly distributed at a peripheral of the drilling rig, four passive impellers contact with a hole wall of a borehole during the drilling process for passively generating relative rotation opposite to the rotation direction of the drill bit, so as to accelerate sufficient mixing of silt and water for forming mud during the drilling process.