A downhole assembly includes a bit and a cutting tool uphole of the bit. The cutting tool has one or more expandable cutter arms. The one or more expandable cutter arms include at least one stabilizer portion having a radial position that is about the same as a gauge of the bit when the one or more expandable cutter arms are in an expanded position. A spline on the cutter arms are used by a cutting tool to move the cutter arms.

A rotary drill bit includes movable gauge elements biased to protrude radially through a circumferential engagement surface of a gauge pad. The gauge elements are retractable to protrude a lesser distance against the bias of a biasing mechanism. Fluid chambers are defined adjacent the gauge elements, and fluid is permitted to be bled into and out of the fluid chambers to delay and slow the retraction and extension of the gauge elements. During straight drilling operations, the biasing mechanisms maintain the gauge elements in an extended position providing stability to the drill bit. When a steering force is applied to the drill bit, the gauge elements retract slowly as fluid is bled from the fluid chambers. As the gauge elements rotate with the drill bit, the retracted configuration may be maintained as gauge elements disengage the geologic formation on a side of the drill bit opposite the steering direction.

An example drill bit is formed by a bit head portion and a shank portion. The bit head portion includes a bit face, and the shank includes a bit portion and a bit connection. The bit connection is configured to be coupled to a drill string. The bit head and shank are configured to be secured together. When secured together, one or more blades that start near a central axis of the bit face continue to a gage portion of the bit and along at least a portion of the length of the bit portion of the shank. One or more anchoring elements are coupled to the bit head and the shank to restrict relative rotational or axial movement between the bit head and the shank.

A rotary drill bit is operable for forming a wellbore in a geologic formation, and includes a hybrid gauge pad thereon. The hybrid gauge pad includes movable gauge elements biased to protrude radially from a circumferential engagement surface of the gauge pad to define a full gauge of the of the drill bit. The movable gauge elements retract and become flush with the circumferential engagement surface of the gauge pad in response to the application of a steering force to the drill bit, and thus, the circumferential engagement surface of the gauge pad may define the full gauge of the drill bit in a second configuration. The gauge elements are axially spaced from one another and are arranged to provide either uniform engagement forces, or decreasing engagement forces in an axial direction of the drill bit.

A cutter block includes a formation facing surface having a staged cutting profile and one or more stabilizer pads may be located between reaming portions. A shorter stabilizer pad or no stabilizer pad may be at the gauge of the cutter block. A spline on the cutter block and used by a downhole cutting apparatus to move the cutter block may intersect the formation facing surface. The spline may form an extension that increases a width of the formation facing surface. The extension may be located at a stabilizer pad to expand the stabilizer pad, such that the extension rotationally leads or trails cutting structure of the cutter block. When the cutter block is expanded, a stabilizer pad may be at a pilot diameter of a wellbore, while some cutting elements may be radially outside, and others radially within, the pilot diameter of the wellbore.

A fixed cutting structure-composite cone drill bit includes a drill bit body, a fixed cutting structure, and at least one cone. The cone and the fixed cutting structure are disposed on the drill bit body. The cone is rotatably connected to the drill bit body by means of a bearing structure. The distance from the outermost tooth or back cone of the at least one cone to the front side surface of the fixed cutting structure La≤πR/3, and the distance from the outermost tooth or back cone of the at least one cone to the rear side surface of the fixed cutting structure Lb≤πR/3. In the composite drill bit, the distance from the cone to the front/rear side surface of the fixed cutting structure is short, the gap between the cone and the fixed cutting structure is small, transition between cutting structure is smooth.

A polycrystalline diamond drill bit for percussion drilling, in small hole high silica ground is disclosed which has a cutting face having an inner flat face and an outer beveled peripheral surface, a number of first polycrystalline diamond tipped inserts having a first diameter inserted into the inner flat face and the outer beveled peripheral surface, and a number of second polycrystalline diamond tipped inserts having a second diameter inserted into the inner flat face, with the second diameter being different than the first diameter. The cutting angle and the radius of the tip of each insert in addition to the diameter of the inserts, provide for use of a machine thrust pressure and machine torque pressure at low ranges when the PCD bits are used in percussion drilling. The percussion drilling, with larger bits, may be used for rotary oil drilling, and operating at a machine thrust and torque of less than 20 Bar.

A drill bit comprises a bit body having a longitudinal axis and a blade extending radially outward from the longitudinal axis along a face region and axially along a gauge region. A gauge region includes a gauge feature and first and second recessed regions extending axially above and below the gauge feature, respectively. The gauge feature comprises an outermost surface extending radially beyond outer surfaces of the blade in the recessed regions. A method of drilling a borehole comprises rotating the bit about the longitudinal axis, engaging a formation with cutting elements mounted to the face region, and increasing a lateral force applied substantially perpendicular to the longitudinal axis such that radially outer surfaces in the gauge region engage the formation and such that side cutting exhibited by the bit is initially minimal and substantially constant and subsequently increases in a substantially linear manner with increasing lateral force.

The disclosure provides downhole tools with shaft regions that are hardened by a compressive residual stress created when an allotropic material in a precursor region transforms from a first allotrope to a second allotrope in response to heat, while continuing to occupy the same physical space. The disclosure further provides methods of forming such downhole tools.

An apparatus includes a first body, a second body, a shear pin, and a divider. The first body includes a coupling. The second body includes a cutter blade. The shear pin is configured to hold the position of the second body relative to the first body in an open position. The coupling is configured to couple the first body to the second body in a closed position. In the open position, the apparatus defines first and second flow paths for fluids and solids to pass through the apparatus. The first flow path is defined through the first body and through an inner bore of the divider. The second flow path is defined through the first body and through an annulus surrounding the divider. In the closed position, the second flow path is closed, such that solids remain in the annulus surrounding the divider.