A modular reamer for use in a wellbore comprises an uphole end member, a center member, and a downhole member, with reamer sleeves that removably slides over a sleeve mounting portion of the center member or one of the end members, and are held between the end members and the center members when assembled into a downhole tool. The reamer sleeves may be positioned at any desired rotational angle relative to each other and are prevented from rotational movement relative to the center member by spines or keys formed on the mating surfaces of the reamer sleeves and corresponding members of the modular eccentric reamer.

A reaming tool for enlarging an underground borehole has a plurality of cutter assemblies distributed azimuthally around a longitudinal axis of the tool. First, second and possibly more cutter assemblies each have an axially extending length comprising supporting structure bearing a sequence of cutters which have hard surfaces facing in a direction of rotation of the tool and are distributed axially along the length. A plurality of the cutters on the second cutter assembly are at axial positions relative to the tool which are intermediate between axial positions of the cutters on the first cutter assembly. Cutters on further assemblies may also be at intermediate axial positions. Cutters in the overall plurality of sequences are positioned at radial distances from the tool axis which increase as axial distance from an end of the tool increases.

In some aspects, the present disclosure includes systems and methods for rotatably coupling a bottom-hole assembly to a drilling shaft for use in subterranean drilling operations. In one embodiment, the methods of the present disclosure are suitable for underreaming a portion of a wellbore. The methods may comprise rotating a drilling shaft coupled to a drill bit about its axis to form a wellbore; engaging a first locking mechanism rotatably coupled to the drilling shaft with a second locking mechanism coupled to a housing to rotatably couple the drilling shaft and the housing; expanding an expandable reamer attached to the housing; and rotating the housing to widen at least a portion of the wellbore uphole from the drill bit. The bottom-hole may comprise one or more actuators that are selectively operable to engage the first and second locking mechanisms and expand the expandable reamer.

A cutter head arrangement comprising a cutter head portion including a cutter head side wall to define a chamber (or cavity) surrounded by the cutter head side wall. A substantially circular rim portion extends from (a distal end of) the cutter head side wall, the rim portion defining a working, contact face of the cutter head portion. A recessed wall portion extends away from the rim portion inwardly into the chanber so as to be surrounded by the cutter head side wall, with the rim portion and/or the recessed wall portion being fitter with a plurality of cutter elemenets, to enable the cutter head portion to blind bore a pilot hole in use. The recessed wall portion that extends away from the rim portion inwardly into the chamber is a substantially conical body so as to define a conical recess.

Systems and methods for adjusting a drilling operation, the methods and systems include obtaining, at a control system, a first drilling characteristic associated with a first drilling operation device that is part of a drilling system on a drill string; obtaining, at the control system, a second drilling characteristic associated with a second drilling operation device located apart from the first drilling operation device along the drill string; and controlling, with the control system, at least one adjustable element of the first drilling operation device in response to at least one of the obtained first drilling characteristic and the second drilling characteristic, wherein adjustment of the at least one adjustable element causes a change in at least one of the first drilling characteristic and the second drilling characteristic.

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 in rows that may extend at an angle across a width of the formation facing surface. Mud flutes may optionally be located between rows of cutting elements. A gauge portion of the formation facing surface may be adjacent a leading edge having reinforcement members coupled thereto.

Disclosed is a hammer reamer comprising cutting wheels, a product-pulling feature, and a hammer component operable to deliver a percussive cycle of an internal piston component. Notably, an internal impact surface within the head of the hammer reamer is positioned relative to the piston component in the hammer consistent with a sweet spot position of a drill bit used in a pilot boring configuration. Unlike a slidably engaged drill bit, however, the internal impact surface in the hammer reamer is fixed in place so that the impact surface remains in the sweet spot of the piston stroke range. In this way, even though the hammer reamer is being pulled back through a bore while the drill string is being retracted, the hammer component may continue to deliver percussive blows to the hammer reamer head to introduce a vibratory force that contributes to the efficiency of the reaming process.

A drilling tool includes a pilot bit coupled to an eccentric reamer that has a reaming side and a stabilizing side. A fluid passageway extends between the reamer and the pilot bit, and the tool includes at least one upwardly-directed nozzle in fluid communication with the fluid passageway and positioned on the stabilizing side of the reamer. The reamer may include a plurality of angularly spaced blades on the reaming side that radially extend a first distance, the reamer blades being disposed within a first arcuate segment defined by the two most distant reamer blades. One or more stabilizing blades extend a second distance that is less than the first distance, the stabilization blades being disposed within a second arcuate segment defined by the two most distant reamer blades and that has the angular measure equal to 360 degrees minus the first arcuate segment.

A downhole-milling-tool method for milling through hard substances, such as barite, found in underground wells, providing a stepped increase of diameters and positioning of carbide cutters and appropriate positioning of fluid ports and channels, to provide removal of cuttings and cooling and lubricating of the cutting head, in turn providing more efficiency and a better rate of penetration (ROP).

A downhole cutting tool which may be a reamer or a mill has a rotary tool body with at least one block which carries hard-faced cutters and projects or is extensible from the tool body. A radially outward facing part of the cutter block defines a channel for fluid flow which extends generally axially along the cutter block. The channel is configured such that at least the rotationally trailing edge of the channel extends along the block in one or more directions which are inclined relative to the tool axis. This reduces or avoids the amount of channel edge parallel to the tool axis and thereby mitigates whirling and/or or vibration.