Cutter blades extend and stay extended as long as pressure on a piston is continued. The blades either open fully in open hole or cut through the wall of a tubular and then mill in an uphole direction to take out a piece of the tubular. The piston that held out the blades when pressure was applied is acted on by a return bias when the pressure is removed so that the blades can retract and the tool removed through the cut tubular. As a backup a plug can be dropped to obstruct a through passage in the piston so that pressure from the surface can be used to force the piston back to retract the blades. Continued drilling operations or the cut and milled portion can be then blocked off such as with cement for a plug and abandonment of the well.

A tool for use in a borehole to perform a milling, under reaming, or other cutting operation includes a tool body configured for rotation about its longitudinal axis, within the borehole, and a set of cutters, the set including two or more cutters which, at least in a deployed configuration, extend outwardly from the tool body and are fixedly coupled together whilst being pivotally coupled to the tool body substantially on said axis so that the cutters rotate with the tool body whilst being pivotable together relative to the tool body during cutting.

The present invention relates to a downhole tool (23), for removing sections of metal tubing, comprising: at least one conductive element (1) being arranged to corrode a section of metal tubing using an electrolytic process, said conductive element (1) being a tube or a pipe which is made of electric conductive material, an apparatus (4) to establish a connection to the metal tubing (2), and a milling apparatus with cutting or abrasive elements (3) arranged to remove byproducts from the electrolytic process. The invention also relates to a modular downhole tool (45), comprising an elongated main shaft (8) with several modules for insertion in a wellbore.

Dual section mills are selectively sequentially operated by locking an actuator for the backup mill as the primary mill has blades extended with internal flow through a housing. When the primary mill is spent the support string is shifted to defeat a lock on an actuation piston for the backup mill so that its blades can extend and continue to mill to finish the job. The blades of the primary mill continue to rotate in the already milled portion of the window as the secondary mill enlarges the window. Another way the secondary mill is actuated is to open access to flow to the secondary mill by removing a pressure barrier such as a valve or a disappearing plug, for example.

A method and apparatus for a locking system for a downhole tool. The locking system includes a first portion having a plurality of displaceable members, a second portion disposed around the first portion; a locked position wherein axial movement between the members is prevented; and an unlocked position wherein axial movement between the members is permitted.

A multi-string section milling tool has a longitudinally extending tubular body with mill carriers carrying hardened cutters that pivotally extend from a mill window in the tubular body by upward movement of a drive plunger. A downwardly biased piston mounted to the upper end of a flow tube is slidably inserted through a stationary thimble below the piston. The lower end of the flow tube is attached to a drive plunger which is pivotally attached to drive yoke links pivotally attached the mill carriers. The piston and thimble creates a pressure chamber in the milling tool. Fluid pressure in the pressure chamber moves the piston, flow tube and drive plunger upward to pivotally extend the drive yoke links and mill carriers radially outward through the mill window. Cessation of fluid pressure in the pressure chamber retracts the mill carriers.

A methodology and apparatus for cutting shape(s) or profile(s) through well tubular(s), or for completely circumferentially severing through multiple tubulars, including all tubing, pipe, casing, liners, cement, other material encountered in tubular annuli. This rigless apparatus utilizes a computer-controlled, downhole robotic three-axis rotary mill to effectively generate a shape(s) or profile(s) through, or to completely sever in a 360 degree horizontal plane wells with multiple, nested strings of tubulars whether the tubulars are concentrically aligned or eccentrically aligned. This is useful for well abandonment and decommissioning where complete severance is necessitated and explosives are prohibited, or in situations requiring a precise window or other shape to be cut through a single tubular or plurality of tubulars.

The present disclosure provides an apparatus for removing material from an internal surface of a pipe. The apparatus comprises a low-power cutting tool for insertion into the pipe and configured to remove material from an internal surface of the pipe. The cutting tool comprises a housing for insertion within the pipe, a cutting head extending from the housing and a cutting tip for machining the internal surface of the pipe in a machining operation when the cutting tool is inserted into the pipe, and one or more actuators for driving the cutting tip. The apparatus further comprises one or more processors, and a computer-readable memory storing instructions which, when executed by the one or more processors, control the one or more actuators to cause the cutting tip to machine the internal surface of the pipe, such that the cutting tool is maintained in a low-power configuration.

A milling tool for use in a cased wellbore. The milling tool has a housing having a plurality of pockets formed therein. A blade is installed within each pocket and is movable between open and closed positions. The blade projects from the pocket when in an open position. Rotation of the housing causes the blades to move to an open position. The blades remain in a closed position when the housing is not rotating.

Method and apparatus for removing a downhole casing from a well on a single trip. A downhole tool assembly is arranged on a work string having a downhole pull tool, a spear tool, motor unit and cutting device. The downhole pull tool is set inside a first casing string and the spear tool, motor unit and cutting device are located inside a second casing string, located through the first casing string. The downhole pull tool and spear tool can be configured to grip the respective casings during cutting of the second casing string. The cut casing section can then be pulled using the downhole pull tool to dislodge the casing section, whereupon via attachment to the spear tool, the cut casing section can be removed from the well. The assembly can be re-set at shallower depths in the event that the cut casing section cannot be dislodged for removal.