A cutting element may include a substrate; and an ultrahard layer on the substrate, the ultrahard layer including a non-planar working surface that is surrounded by a peripheral edge having a varying height around a circumference of the cutting element, the working surface also having: a plurality of cutting crests extending from an elevated portion of the peripheral edge across at least a portion of the working surface; at least one valley between the plurality of cutting crests; and a canted surface extending laterally from each of the outer plurality of cutting crests towards a depressed portion of the peripheral edge, a height between the depressed portion and the elevated portion being greater than a height between the elevated portion and the valley.

A cutting element may include a substrate; and an ultrahard layer on the substrate, the ultrahard layer including a non-planar working surface that is surrounded by a peripheral edge having a varying height around a circumference of the cutting element, the working surface also having: a plurality of cutting crests extending from an elevated portion of the peripheral edge across at least a portion of the working surface; at least one valley between the plurality of cutting crests; and a canted surface extending laterally from each of the outer plurality of cutting crests towards a depressed portion of the peripheral edge, a height between the depressed portion and the elevated portion being greater than a height between the elevated portion and the valley.

Fixed-cutter matrix bits comprising hardfaced elements on the gauge pads, and methods of manufacture and using. An example fixed-cutter matrix bit comprises a matrix bit body, a plurality of cutter elements secured at fixed locations to the matrix bit body, and a plurality of gauge pads disposed on the matrix bit body; wherein at least one of the gauge pads includes a hardfaced exterior surface. The hardfaced exterior surface may comprise a material selected from the group consisting of tungsten, niobium, vanadium, molybdenum, silicon, titanium, tantalum, zirconium, chromium, yttrium, boron, carbon, carbides thereof, nitrides thereof, borides thereof, oxides thereof, silicides thereof, and combinations thereof. The hardfaced exterior surface may be fused to the at least one gauge pad during the infiltration process of manufacturing the matrix bit body.

Fixed-cutter matrix bits comprising hardfaced elements on the gauge pads, and methods of manufacture and using. An example fixed-cutter matrix bit comprises a matrix bit body, a plurality of cutter elements secured at fixed locations to the matrix bit body, and a plurality of gauge pads disposed on the matrix bit body; wherein at least one of the gauge pads includes a hardfaced exterior surface. The hardfaced exterior surface may comprise a material selected from the group consisting of tungsten, niobium, vanadium, molybdenum, silicon, titanium, tantalum, zirconium, chromium, yttrium, boron, carbon, carbides thereof, nitrides thereof, borides thereof, oxides thereof, silicides thereof, and combinations thereof. The hardfaced exterior surface may be fused to the at least one gauge pad during the infiltration process of manufacturing the matrix bit body.

A cutting element for a drill bit can include a first layer of polycrystalline diamond, a second layer of polycrystalline diamond, wherein a boundary between the first layer and the second layer is nonplanar, and a substrate. The first and second layers can be formed from polycrystalline diamond of different grain sizes. One of the first and second layers can be leached of a catalyzing material. The first layer can be formed on a first substrate having a nonplanar surface feature, removed from the first substrate, and placed over the second layer to form the nonplanar boundary. The first layer can be leached of a catalyzing material prior to being applied to the second layer. A barrier layer can be placed between the first layer and the second layer to prevent sweeping of a catalyzing material into the leached first layer.

Cutting elements are installed on the outer surface of a drill bit body such that the surface profile supports the plurality of cutting elements in a desired orientation. Each cutting element has a substrate with a rear end, a leading end that carries a cutting portion, and a cylindrical surface therebetween. The cutting elements are installed within a cavity on the drill bit body such that a portion of the substrate is exposed and the leading end leads the cutting element in a direction of rotation of the drill bit body. The cutting elements are bound on the outer surface by applying a composite to the outer surface and to the portion of the substrate that is exposed. The composite is a mixture of a matrix and cutting fragments and is in direct contact with about 40-75%% of the surface area of the substrate.

Cutting elements are installed on the outer surface of a drill bit body such that the surface profile supports the plurality of cutting elements in a desired orientation. Each cutting element has a substrate with a rear end, a leading end that carries a cutting portion, and a cylindrical surface therebetween. The cutting elements are installed within a cavity on the drill bit body such that a portion of the substrate is exposed and the leading end leads the cutting element in a direction of rotation of the drill bit body. The cutting elements are bound on the outer surface by applying a composite to the outer surface and to the portion of the substrate that is exposed. The composite is a mixture of a matrix and cutting fragments and is in direct contact with about 40-75%% of the surface area of the substrate.

A drill bit for removing subterranean formation material in a borehole comprises a bit body comprising a longitudinal axis, a plurality of blades extending radially outward from the longitudinal axis along a face region of the bit body and extending axially along a gauge region of the bit body, and an insert coupled to at least one blade in the gauge region. The insert comprises an elongated body having an upper surface, a lower surface, and a longitudinal axis extending centrally therethrough and intersecting the upper and lower surfaces. The upper surface comprises a bearing surface for supporting for the drill bit and providing a surface on which the subterranean formation being drilled rubs against the insert without exceeding the compressive strength of the selected formation. The insert is coupled to the blade such that the upper surface thereof extends radially beyond an outer surface of the blade and the lower surface thereof extends radially below the outer surface of the blade.

A drill bit for removing subterranean formation material in a borehole comprises a bit body comprising a longitudinal axis, a plurality of blades extending radially outward from the longitudinal axis along a face region of the bit body and extending axially along a gauge region of the bit body, and an insert coupled to at least one blade in the gauge region. The insert comprises an elongated body having an upper surface, a lower surface, and a longitudinal axis extending centrally therethrough and intersecting the upper and lower surfaces. The upper surface comprises a bearing surface for supporting for the drill bit and providing a surface on which the subterranean formation being drilled rubs against the insert without exceeding the compressive strength of the selected formation. The insert is coupled to the blade such that the upper surface thereof extends radially beyond an outer surface of the blade and the lower surface thereof extends radially below the outer surface of the blade.

A method of manufacturing an earth-boring tool to reduce a carbon footprint of the earth-boring tool includes calculating an amount of CO.sub.2 associated with forming a drill bit. The method additionally includes redesigning the drill bit to reduce the amount of CO.sub.2 associated with forming the drill bit. The method may further include forming the redesigned drill bit. Related drill bits with reduced carbon footprints are also described.