A reamer includes a housing, a first reamer block, and a second reamer block. The first reamer block includes a leading wall. A second reamer block includes a trailing wall, the trailing wall including a recess. The leading wall is inserted into or nested in the recess to increase the coverage-to-exposure ratio.

An underreamer for increasing a diameter of a wellbore. The underreamer may include a body having an axial bore extending at least partially therethrough. An electromagnetic activation system may be disposed at least partially within the bore of the body. A valve may be disposed within the bore of the body and coupled to the electromagnetic activation system. The valve may include a mobile element and a static element. The mobile element may be coupled to the electromagnetic activation system and move from a first position where the mobile element obstructs fluid flow through the valve to a second position where the mobile element permits fluid flow through the valve. A cutter block may be movably coupled to the body and move radially-outward as the mobile element moves from the first position to the second position.

A drill bit for drilling a bore, the drill bit comprising: an outer housing; a primary cutting structure defining a cutting plane of a first diameter; a flow path arranged to let drilling fluid flow through the drill bit; and a deployable blade assembly at least partially located within the outer housing, the deployable blade assembly comprising a cutting structure and being arranged to be axially movable from a first position, in which the deployable cutting structure is recessed with respect to the primary cutting structure, towards the cutting plane, to a second position; wherein when the deployable blade assembly is in the second position, the deployable cutting structure defines a cutting diameter which is less than or equal to the first diameter.

An actuation system to control flow of a fluid includes a body including an axial cavity and a valve in fluid communication with the axial cavity, the valve including a closing member moveable into and out of a closed position against the valve seat, and a resistance member. Fluid from the axial cavity can flow through and out of the valve when the closing member is out of the closed position and the closing member is biased into or out of the closed position by a force applied by the resistance member. The closing member is movable out of or into the closed position upon a rotational speed and fluid pressure within the axial cavity being sufficient to overcome the force applied by the resistance member.

The present invention discloses a liquid injection type reamer bit, which comprises a drilling and reaming rod (1), a drilling tool (2) and reaming tools (3). The reamer bit is adopted to perform drilling and reaming operations respectively in a water pressure adjusting manner, has the advantages of simple structure, convenient operation, small volume, light weight, flexible and reliable technology, unified power sources for drilling and reaming, stable reaming, easy recovery of tools, and realization of reaming while drilling, greatly improves the anchoring reliability of anchor bolts, and ensures the safety of workers during underground work.

A system for extracting gas from a tectonically-deformed coal seam in-situ by depressurizing a horizontal well cavity is provided. A horizontal well is constructed by a horizontal well drilling and reaming subsystem and adjoins a vertical well to form a U-shaped well, and a horizontal section of the horizontal well is reamed to enlarge hole diameter. A horizontal well hole-collapse cavity-construction depressurization excitation subsystem performs pressure-pulse excitation and stress release on the horizontal well of tectonically-deformed coal bed methane, and hydraulically displaces a coal-liquid-gas mixture such that the mixture is conveyed towards a vertical well section along a depressurizing space. A product lifting subsystem further pulverizes the coal and lifts the mixture towards a wellhead of a vertical well. A gas-liquid-solid separation subsystem separates the coal, liquid and gas. A monitoring and control subsystem detects and controls the operation conditions and the execution processes of technical equipment in real time.

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 downhole drilling apparatus, passing through a subterranean borehole, may mark an inner wall of the borehole with a marking element. A sensor, spaced axially from the marking element on the drilling apparatus, may subsequently sense the marking as it passes. A rate of penetration of the drilling apparatus may be calculated by dividing an axial distance, between the marking element and the sensor, by a time interval, between when the marking element marks the inner wall and when the marking is sensed by the sensor. Alternately, a second sensor, spaced axially from the first, may also sense the marking. A rate of penetration may then be calculated by dividing an axial distance, between the two sensors, by a time interval, between when the two sensors sense the marking.

A downhole cutting tool and method of operating the cutting tool. The cutting tool (10) has first and second flow pathways through the tool body (12) and a switching mechanism operated by axial force via weight-set or drop ball to control the opening of the flow pathways and direct fluid to the second flow path and operate the cutting mechanism (18). Fluid flow through the first pathway can be used to actuate a hydraulically operated tool mounted on the tool string below the cutting tool (10).

A section mill (10) and method of removing a section of tubular (150) from a well. The section mill includes elongate blades (14) which have a cutting structure (66) extending along at least a portion of a length from a first edge (62) and at least a portion of a width from a second edge (64) of the elongate cutter blade, the second edge being longer than the first edge, the first and second edges being perpendicular to each other. The blades are moved axially and radially relative to the tubular body (12) to arrange the second edge parallel to the central longitudinal axis (13) for milling Operation of the mill is in an upwards direction using a hydraulic tensioning device to provide a constant load so that milling of tubular can be achieved in a rigless arrangement.