A device for forming a diameter-enlarged hole portion by cutting into a hole that is formed in a workpiece, the device including: a bow jaw including a shaft and a guide, the guide including a distal end surface and an sloped surface, the distal end surface being provided on an opposite side of the guide from the shaft, the sloped surface being sloped from the shaft side of the guide toward the distal end surface side of the guide in a direction away from a center axis of the shaft; and a cutter blade including a cutting portion whose distal end is provided with a cutting edge, the cutting portion being slidable along the sloped surface. The bow jaw further includes a suction passage that includes a flow passage, the flow passage including a suction port that is open at the distal end surface.

A device for forming a diameter-enlarged hole portion by cutting into a hole that is formed in a workpiece, the device including: a bow jaw including a shaft and a guide, the guide including a distal end surface and an sloped surface, the distal end surface being provided on an opposite side of the guide from the shaft, the sloped surface being sloped from the shaft side of the guide toward the distal end surface side of the guide in a direction away from a center axis of the shaft; and a cutter blade including a cutting portion whose distal end is provided with a cutting edge, the cutting portion being slidable along the sloped surface. The bow jaw further includes a suction passage that includes a flow passage, the flow passage including a suction port that is open at the distal end surface.

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 wellbore is drilled in a formation using a drill string assembly that includes a drill string. A drill bit is connected to a downhole end of the drill string. A notching tool is connected to the drill string. After drilling the wellbore to a depth from a surface in the formation, the drilling is paused. The notching tool is rotated. a notch is formed with the rotating notching tool. In subsequent operations, DSA is removed from the well and the fracturing fluid pumped from the surface can create fractures at the locations of notches. These fractures would improve wellbore connectivity with the reservoir for better oil and gas recovery.

A belling auger includes a rotatable shaft, a main shaft extending through the rotatable shaft, a sliding sleeve mounted on the main shaft a bottom panel and a shovel rotatably attached to the rotatable shaft. Pressing the rotatable shaft down towards the sliding sleeve causes the shovel to hinge outward at the bottom of a piling hole. As the device rotates the shovel scoops dirt onto the pan, thus widening the bottom of the hole to a bell or cone shape.

A belling auger includes a rotatable shaft, a main shaft extending through the rotatable shaft, a sliding sleeve mounted on the main shaft a bottom panel and a shovel rotatably attached to the rotatable shaft. Pressing the rotatable shaft down towards the sliding sleeve causes the shovel to hinge outward at the bottom of a piling hole. As the device rotates the shovel scoops dirt onto the pan, thus widening the bottom of the hole to a bell or cone shape.

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 casing mill including a first milling configuration having a first blade for milling a first casing section, and a second milling configuration having a second blade, the second blade being an ultra-high expansion blade for milling a second casing section. A wellbore system including a borehole in a subsurface formation, two nested casings disposed within the borehole, a string disposed within the casings, a casing mill disposed within or as a part of the string and including a first milling configuration having a first blade for milling a first casing section, and a second milling configuration having a second blade, the second blade being an ultra-high expansion blade for milling a second casing section, the second casing section being radially outwardly disposed of the first casing section, and a stroking tool disposed between the first milling configuration and the second milling configuration.

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.