A method to facilitate the extraction of hydrocarbon from a coal seam gas formation is described that includes. : (a) drilling a wellbore using a drill string to access the coal seam gas formation; (b) perforating a section of the drill string; (c) abandoning a section of the drill string in the wellbore; (d) setting a temporary plug to isolate the abandoned section of the drill string and the wellbore; (e) installing a production tubing string above the temporary plug to create a fluid passageway ; (f) displacing a fluid above the temporary plug ; (g) removing the temporary plug to create an initial stimulated reservoir volume and, resultantly, at least partially filling an annulus formed between the abandoned section of the drill string and the wellbore wall with coal fragments; and (h) extracting hydrocarbon from the coal seam gas formation via the fluid passageway to create an expanding stimulated reservoir volume.

A downhole autonomous jet cutting tool includes a main body with a generally cylindrical configuration. The main body includes a locking unit actuable to engage the tool to an inner surface of the pipe, a hydraulic motor with a rotor and a stator, and a rotatable jet cutting nozzle assembly operable to emit a stream of fluid to cut the pipe. The tool also includes a sensor module to detect interactions between the pipe and walls of the wellbore and a control unit in electronic communication with the sensor module and the locking unit. The control unit can identify, based on output of the sensor module, a location where interaction between the pipe and the walls of the wellbore limits downhole movement of the pipe, actuate the locking unit to engage the tool in the inner surface of the pipe, and initiate the stream of fluid from the nozzle assembly.

An anchor for securing a well tool can include a longitudinally extending central axis, an outwardly extendable grip member, and a mechanical linkage including multiple pivotably connected links. The links pivot relative to each other in a plane laterally offset from the central axis. A method of anchoring a well tool can include flowing a fluid through an anchor connected to the well tool, thereby outwardly extending a grip member into contact with a well surface, and applying a tensile force to the anchor, thereby increasingly biasing the grip member against the well surface and securing the well tool relative to the well surface. A method of anchoring a tubing cutter in a tubular string can include applying a tensile force from an anchor to the tubular string, and cutting the tubular string while the tensile force is applied from the anchor to the tubular string.

An apparatus for cutting and/or milling of tubulars in a wellbore, especially using coiled tubing. An elongated main body has a longitudinal bore, with a piston slidably positioned in the bore. The piston is connected to one or more operating arms which are rotatably connected to the main body. The connection between the piston and the operating arms may be a pinned connection or a geared connection, both of which provide for a positive connection between the piston and the operating arms. Cutter bases are connected to the cutter arms, with a number of cutters mounted to the cutter bases. Fluid flow down the coiled tubing and through the main body bore pushes the piston downwardly, opening the operating arms and cutter bases and permitting the apparatus to be pulled up into the lower end of a tubular string for cutting and/or milling.

This invention relates to a cutting unit for a well pipe. The cutting unit includes a tool housing axially displaceable and rotatable in the well pipe, arranged in the tool housing at least one cutting tool displaceable in a radial direction, the unit connected to a rotary adapter for rotation around a center axis, and the tool housing provided with a leading end portion and a coupling portion, the leading end portion being conical, sloping towards the center axis and away from the coupling portion; and the cutting unit provided with an elongated springable tool mount with a first end portion, a second end portion and a resilient portion between first end portion and second end portion, elongated tool mount positioned in an external recess in the tool housing, and the second end portion positioned at the leading end portion, and the tool mount tensioned towards the center axis; a sleeve positioned around the coupling portion, the first end portion attached to the sleeve; at least one shear body fixing the sleeve to the tool housing; an internal first bevel on the second end portion of the tool mount; a cutting unit attached to the second end portion on the opposite side of the internal first bevel; and a push rod connected to a cone body, cone body resting against the first bevel.

This invention relates to a method for recovering a tubular structure (3) from a well (1), wherein a so-called free point is defined as the location where the tubular structure is stuck in the well. The method comprising providing a downhole tool string comprising a pipe-severing tool and an upper part of the downhole tool string; lowering the downhole tool string into the tubular structure to release the free pipe. Before the step of triggering the pipe-severing tool to sever the tubular structure, the method includes releasing the pipe-severing tool and subsequent withdrawing the upper part, of the downhole tool string away from the free point towards the surface over at least a predefined distance. The invention relates to a downhole tool string for use in such method.

A downhole autonomous cutting tool and methods are described. The downhole autonomous cutting tool including: a body comprising a hydraulic motor, the body having a generally cylindrical configuration such that the body limits a downhole flow of fluids past the autonomous cutting tool between the autonomous cutting tool and the pipe when the tool is deployed in the pipe; a locking unit attached to the body, the locking unit actuable to engage inner surfaces of the pipe in the wellbore; a sensor module operable to detect interactions between the pipe and walls of the wellbore; an actuation unit attached to the body and rotatable by the hydraulic motor, the actuation unit operable to move a plurality of cutting elements between a running position and a cutting position; and a control unit in electronic communication with the sensor module, the locking unit, and the actuation unit.

A rotary tool for operation within an underground wellbore or within tubing in a wellbore has at least one force-sensitive element attached to the tool body and positioned to contact the conduit wall, wherein the force-sensitive element comprises an outer portion to contact the wellbore or tubing wall, at least one connecting portion which is more compliant than the outer portion and through which the outer portion is connected to the tool body, and at least one sensor responsive to force on the outer portion transmitted through the force-sensitive element to the tool body. The sensors may resolve forces into measurable forces on three axes. Possible rotary tools include drill bit, reamer, mill, stabilizer and rotary steerable system for a drill bit.

A sealing tool for conveyance within a tubular member within a wellbore extending into a subterranean formation. The sealing tool includes a mandrel and a eutectic sealing material disposed about the mandrel. The eutectic sealing material has a eutectic temperature at which the eutectic sealing material melts. The sealing tool also includes means for heating the eutectic sealing material to at least the eutectic temperature. The eutectic sealing material is transferred onto an inner surface of the tubular member by activating the heating means to heat the eutectic sealing material to at least the eutectic temperature to melt the eutectic sealing material.