Cutting tool and method of cutting an object in a well

A cutting device cuts one or more downhole control lines such that the cut ends of the one or more control lines will not interfere with subsequent fishing operations. The cutting device comprises a mandrel, a cutting sleeve and a housing supported on a tubing. Movement of the tubing induces relative motion of the cutting sleeve to cut the one or more control lines.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to the field of cutting tools, particularly to a device and method to cut a control line downhole in a well.

2. Related Art

With the advent of intelligent completions, running multiple control lines downhole along completions equipment is common practice. Unfortunate occurrences sometimes require cutting the downhole tubing to retrieve the completion equipment. In those cases, the control lines can complicate the retrieval operations if the control lines are pulled apart above the tubing cut. Ideally, the control lines are cut below the tubing cut to recover as much of the control lines as possible and leave a clean “fish” downhole.

Prior systems use a “splice sub” in which the control lines are anchored above and below the tubing cutting target length. A tubing cutter such as an Explosive Jet Cutter (EJC) is run to target depth and detonated to cut the tubing. Excess impact from the EJC at least partially cuts the control lines. When the tubing is removed, the control lines, if not completed severed, break at the damaged area, leaving the remaining control line portions in the vicinity of the remaining tubing. The remaining tubing is more easily “fished” if it is clear of control line remnants.

SUMMARY OF INVENTION

The present invention provides for a cutting device and associated method to cut one or more downhole control lines such that the cut ends of the control lines will not interfere with subsequent fishing operations.

DETAILED DESCRIPTION

Referring toFIG. 1, a cutting tool10comprises four primary components: a mandrel12, a cutting sleeve14, a housing16, and lugs18.FIG. 1also shows a single control line19, though the invention is not limited to just one control line. Other figures (e.g.,FIGS. 3 and 4) show, for example, five control lines19. Control line19may be, for example, a hydraulic conduit, an electric cable, a fiber optic cable, or a combination of those, as well as other devices manifested as a relatively small diameter longitudinal line. A seal21is mounted near the lower end of mandrel12and serves to prevent the upward invasion of dust and debris.

InFIG. 1, housing16is shown retracted from its operational configuration to expose the underlying components. Housing16normally encloses mandrel12and sleeve14. Mandrel12provides a tubing cutting target20and carries a cutting base22near its lower end below target20. Base22can be integral to mandrel12or can be made as a separate component and attached to mandrel12. Mandrel12mounts at its upper end to an upper end of housing16, and at its lower end to a lower portion of a tubing24. Housing16attaches at its upper end to an upper portion of tubing24. Tubing24, housing16, and mandrel12, when so assembled, form a continuous passageway for fluid flow.

Sleeve14is carried on the lower end of mandrel12and can move in both rotation and translation relative to mandrel12and base22. The relative motion provides a cutting action. Base22and sleeve14have mating helical surfaces28and each has a longitudinal passageway through its respective sidewall to accommodate control line19. Those passageways are initially aligned. Axial holes31in mandrel12and axial holes33in base22ofFIG. 1show the passageway openings accommodating control line19.

Lugs18are carried in slots26of sleeve14and placed in sliding engagement with the lower end of mandrel12. Lugs18extend into a groove29in the inner surface of housing16, linking sleeve14to housing16while permitting sleeve14to rotate relative to housing16. A recess35in mandrel12allows lugs18to disengage from housing16upon sufficient displacement of sleeve14.

In operation, a tubing cutter34such as an explosive jet cutter is placed in the vicinity of tubing cutting target20. The cutter34is actuated to sever mandrel12somewhere along the length of target20. Once mandrel12is severed, the upper portion of tubing24is pulled upward by the operator. Because housing16is attached to the upper portion of tubing24, housing16is pulled upward as well. Since lugs18extend into groove29of housing16, sleeve14is also pulled upward. Thus, housing16provides a mechanical link between the upper portion of tubing24(that has now been severed from the lower portion of tubing24) and cutting sleeve14to generate the relative motion required for cutting control line19.

Helical surfaces28between sleeve14and cutting base22cause sleeve14to rotate relative to base22when sleeve14is pulled upward. The rotational motion advances the cutting edge of sleeve14through control line19, thereby cutting control line19. With sufficient upward travel of cutting sleeve14, lugs18encounter and retract into recess35in mandrel12to release housing16.

Once housing16is released, the upper portion of tubing24, along with housing16and the upper portion of (severed) mandrel12can all be removed from the well. The newly cut end of the upper portion of control line19is enclosed inside housing16during retrieval. The severed end of the lower portion of control line19left in the well is enclosed inside sleeve14. The lower portion of tubing24remains in the well and the uppermost end of the severed lower portion of mandrel12is clear of control lines19. Preferably the severed end of mandrel12is beveled to allow for easy overshoot. Additionally, the outside diameter of sleeve14is preferably small enough to be swallowed up (i.e., enclosed and captured), for example, by a burner mill. This allows for removal of the remaining portion of the completion assembly from the well.

FIGS. 2–4show an embodiment of cutting tool10in which the elements are eccentrically aligned. The eccentric design accommodates more or larger control lines19.

FIGS. 5–7show an embodiment of cutting tool10in which the elements are concentrically aligned. When requirements permit, a concentric design allows for simpler manufacture.

FIGS. 8–10show alternative embodiments of cutting tool10in which the roles of cutter sleeve14and base22are reversed. A thrust bearing36is placed above cutter sleeve14to better allow sleeve14to rotate. Base22can be integral to mandrel12or can be made as a separate component and attached to mandrel12. Base22and cutter sleeve14remain the two arms of the scissors and their helical profiles induce relative rotation between them. They can be manufactured from the same tube to ensure a conformable mating surface. The roles are reversed because the lower portion (base22) is now fixed to mandrel12. The upper portion (sleeve14) is now the component that rotates.

FIGS. 8 and 9show an embodiment in which dual tubing strings are used. Primary string38and secondary string40mount in a fashion similar to that described above to housing16and mandrel12. If it becomes necessary to cut control lines19, tubing strings38,40are first cut as before. Gaps in sleeve14around string40and within housing16allow sleeve14to rotate, cutting control lines19.

FIG. 10also shows other features such as housing16having a channel41along its entire length such that housing16effectively forms a “C-ring”. That allows control lines19to be laid through channel41alongside mandrel12without regard to alignment holes31. Channel41in housing16is rotated to align with the channels (instead of holes33) in the base22and cutter sleeve14and control lines19are installed through the channels one line at a time. Housing16can then be rotated over control lines19to protect them from external hazards in the well. To avoid hoop stresses in housing16, square threads42and square lugs18are preferred. Lugs18may also need to be spring loaded to insure proper retraction from housing16. Base22can be restrained by clutch43to limit the motion of base22to translation only.