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.

A drill bit for subterranean drilling operations is disclosed. The drill bit comprises a drill bit body with one or more blades. The drill bit further comprises a plurality of primary cutters, each primary cutter located on at least one blade, and a plurality of secondary cutters, each secondary cutter located on at least one blade other than the blade on which the primary cutters are located.

A drill bit for subterranean drilling operations is disclosed. The drill bit comprises a drill bit body with one or more blades. The drill bit further comprises a plurality of primary cutters, each primary cutter located on at least one blade, and a plurality of secondary cutters, each secondary cutter located on at least one blade other than the blade on which the primary cutters are located.

An earth-boring tool includes a body having a plurality of blades. Each blade of the plurality of blades extends axially and radially relative to a center longitudinal axis of the body. The earth-boring tool further includes a plurality of cutting elements secured within the plurality of blades and at least one protrusion trailing at least one cutting element of the plurality of cutting elements in a direction of intended rotation of the earth-boring tool and extending along a lateral side of a blade of the plurality of blades in which the at least one cutting element is secured. The earth-boring tool may further include a pocket extending into the at least one blade from a rotationally leading face of the at least one blade in at least a shoulder region of the at least one blade.

An earth-boring tool includes a body having a plurality of blades. Each blade of the plurality of blades extends axially and radially relative to a center longitudinal axis of the body. The earth-boring tool further includes a plurality of cutting elements secured within the plurality of blades and at least one protrusion trailing at least one cutting element of the plurality of cutting elements in a direction of intended rotation of the earth-boring tool and extending along a lateral side of a blade of the plurality of blades in which the at least one cutting element is secured. The earth-boring tool may further include a pocket extending into the at least one blade from a rotationally leading face of the at least one blade in at least a shoulder region of the at least one blade.

Cutting elements for earth-boring tools may include a rotationally leading end positioned and configured to engage with, and remove, a material of an earth formation. A transition region may extend from proximate to a periphery of the cutting element radially inward and axially toward the rotationally leading end. The transition region may include first faceted surfaces, each first faceted surface extending at a first angle relative to a central geometric axis of the cutting element. The transition region may also include second faceted surfaces, each second faceted surface extending at a second, different angle relative to the central geometric axis of the cutting element. The first faceted surfaces and the second faceted surfaces may intersect one another at edges around a periphery of the transition region.

Cutting elements for earth-boring tools may include a rotationally leading end positioned and configured to engage with, and remove, a material of an earth formation. A transition region may extend from proximate to a periphery of the cutting element radially inward and axially toward the rotationally leading end. The transition region may include first faceted surfaces, each first faceted surface extending at a first angle relative to a central geometric axis of the cutting element. The transition region may also include second faceted surfaces, each second faceted surface extending at a second, different angle relative to the central geometric axis of the cutting element. The first faceted surfaces and the second faceted surfaces may intersect one another at edges around a periphery of the transition region.

A drill bit includes a bit body providing one or more blades and defining a cone section extending from a centerline of the bit body a first distance, a nose section extending from the cone section a second distance, a shoulder section extending from the nose section a third distance, and a gauge section extending from the shoulder section a fourth distance. The drill but further includes one or more cutting elements mounted to the one or more blades outside of the cone section such that the cone section is void of cutting elements, and a plurality of milling elements secured to the bit body within the cone section.

A drill bit includes a bit body providing one or more blades and defining a cone section extending from a centerline of the bit body a first distance, a nose section extending from the cone section a second distance, a shoulder section extending from the nose section a third distance, and a gauge section extending from the shoulder section a fourth distance. The drill but further includes one or more cutting elements mounted to the one or more blades outside of the cone section such that the cone section is void of cutting elements, and a plurality of milling elements secured to the bit body within the cone section.

Methods for attaching cutting elements to an earth-boring bit rely on keying the cutting elements inside cavities formed in the earth-boring bit. The attachment methods may involve specific shapes of the cutting elements and the cavities in which the cutting elements are received, and/or mechanical retainers. Preferably, the blade of the earth-boring bit is thicker around the opening in the edge of the blade than when the cavity is shaped for receiving a cutting element that has a circular cross-section.