A downhole tool assembly coupled to a drill string includes a drill string motor that rotates the drill string, the downhole tool assembly including a tool body defining a perimeter, one or more cutting elements positioned on the perimeter of the tool body, where the one or more cutting elements are positionable between an extended position, in which the one or more cutting elements extend outwardly from the perimeter of the tool body, and a retracted position, where the one or more cutting elements are positioned further outward from the perimeter of the tool body in the extended position than the retracted position, and a tool motor coupled to the tool body, where the tool motor is structurally configured to rotate the tool body as fluid passes through the tool motor.

A flow rate control system includes a housing and a valve assembly slidingly disposed within a housing inner bore. The housing includes bypass openings. The valve assembly includes a valve and an orifice disposed in a valve inner bore. The valve includes a plurality of valve bypass bores extending axially through a valve collar. The valve assembly slides between closed and fully open positions. A spring biases the valve assembly toward the closed position in which the valve closes the housing bypass openings. In the open position, a bypass fluid path is formed including the valve bypass bores and the housing bypass openings. The valve assembly is flow rate controlled in the closed position and pressure controlled in the open position. The valve assembly may slide within a sleeve assembly including sleeve bypass openings, which connect the valve bypass bores and housing bypass openings in the bypass fluid path.

Provided is a downhole tool, a well system, and a method for forming a well system. The downhole tool, in at least one aspect, includes a two part drilling and running tool, the two part drilling and running tool including a conveyance, a smaller assembly coupled to an end of the conveyance, and a larger bit assembly slidably coupled to the conveyance, the smaller assembly and larger bit assembly configured to slidingly engage one another downhole to form a combined bit assembly. The downhole tool, in accordance with this aspect, further includes a whipstock assembly coupled to the two part drilling and running tool using a coupling mechanism, and a hydraulically actuated anchoring assembly coupled to a downhole end of the whipstock assembly.

A downhole cutting apparatus includes a cutter block. The cutter block includes a formation facing surface with cutting elements coupled thereto. The cutting elements are arranged such that at least one cutting element has a different exposure relative to the formation facing surface than at least one other cutting element. In some embodiments, a row of cutting elements may have a gradually changing exposure. The exposure may change such that cutting elements nearer the gauge of the cutter block have less exposure than cutting elements farther from the gauge of the cutter block. In additional embodiments, an underreamer may include multiple cutter blocks. The cutter blocks may each have a different configuration in a backreaming portion, gauge portion, underreaming portion, any part thereof, or in a combination of the foregoing.

A flow rate control system includes a housing and a valve assembly slidingly disposed within a housing inner bore. The housing includes bypass openings. The valve assembly includes a valve and an orifice disposed in a valve inner bore. The valve includes a plurality of valve bypass bores extending axially through a valve collar. The valve assembly slides between closed and fully open positions. A spring biases the valve assembly toward the closed position in which the valve closes the housing bypass openings. In the open position, a bypass fluid path is formed including the valve bypass bores and the housing bypass openings. The valve assembly is flow rate controlled in the closed position and pressure controlled in the open position. The valve assembly may slide within a sleeve assembly including sleeve bypass openings, which connect the valve bypass bores and housing bypass openings in the bypass fluid path.

A reamer includes a housing, a flow tube extending along a longitudinal axis of the housing, and a plurality of reamer blocks arranged radially around the flow tube and configured to extend and retract relative to the housing. The reamer has a reamer ratio between 1.8 and 2.5. The reamer ratio is a ratio between an expanded diameter of the reamer when the plurality of reamer blocks is extended and a retracted diameter of the reamer when the plurality of reamer blocks is retracted.

A wellbore assembly includes a drill string, a drill bit, and a reamer assembly. The reamer assembly is coupled to the drill string uphole of the drill bit and includes a side cutter. The reamer assembly includes a spring that moves the side cutter from an extended position, in which the side cutter is retained by a portion of the reamer assembly against inward movement and in which the cutter defines a first drilling diameter greater than a drilling diameter of the drill bit, to a retracted position in which the portion of the reamer assembly has been broken by a shear force applied by the side cutter under a weight on bit applied against an inner component of the casing. In the retracted position, the side cutter is housed within the housing and defines a drilling diameter equal to or less than the drilling diameter of the drill bit.

A tool for building a wellbore includes a tool body with a flow passage extending axially therethrough, a piston chamber formed radially through the tool body that intersects the flow passage of the tool body, a piston disposed in the piston chamber, at least one actuation element that exerts a force between the piston and the piston chamber, and a sleeve disposed within the flow passage of the tool body that includes at least one cutout. When the sleeve is in a first position within the tool body, the cutout is axially offset from the piston, and when the sleeve is in a second position, the cutout is axially aligned with the piston.

A downhole drilling tool, forming part of a subterranean drilling system, may include at least one plate secured to an exterior of an elongate body. Electronics may be disposed between the plate and the body to be protected by the plate while still readily accessible. A dynamic element may be radially extendable from the plate to engage an inner wall of a borehole being drilled. If this radially-extendable element becomes worn or damaged from this engagement, the plate may be replaced. More expensive components of the drilling tool may be contained within the elongate body, rather than the plate, thus reducing replacement frequency. Additionally, plates including unique features may be employed at different times without altering the underlying elongate body.

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.