GB2523174A

GB2523174A - Control cable removal

Info

Publication number: GB2523174A
Application number: GB1402773.4A
Authority: GB
Inventors: Pã L Viggo Hemmingsen; Gjermund Grimsbo; Marcus Fathi
Original assignee: Statoil Petroleum ASA
Current assignee: Equinor Energy AS
Priority date: 2014-02-17
Filing date: 2014-02-17
Publication date: 2015-08-19
Anticipated expiration: 2034-02-17
Also published as: GB201402773D0; GB2523174B

Abstract

A method of preparing a well for subsequent plugging, the well comprising a casing1, a tubular 2 provided within the casing, and a cable 3 provided between the casing and the tubular; the method comprising providing within the tubular a means 5 for cutting the tubular and the cable, cutting the tubular and the cable with said means along a helical path 6 on the wall of the tubular in order to sever the cable at a plurality of locations 7 without severing the tubular. The cutting means may be a wireline, abrasive, thermal, chemical, explosive or mechanical. Also independently claimed is removing a part of a cable by severing the cable, forming an opening in the tubular and removing a portion of the cable and a method of preparing a well for plugging by filling the annulus between the casing and the tubular with an insulating material and removing part of the tubular and cable by thermal energy.

Description

Control cable removal

Background

The integrity of a well in drilling and wel operation, including placement of a plug and abandonment of a well, may be compromised by the presence of control cables.

Control cables may create vertical leak paths through a well barrier. The problem lies specifically with the insulation material of the electrical or hydraulic control cables, which may degrade in contact with hydrocarbons or which may be damaged during placement of a barrier, creating void space between the plug material and the metal cable. Degradation of the cable material could also happen during manufacturing of the cable, running the cable in the well and by downhole conditions. Another problem is hydraulic cables, which are hollow and therefore cannot be a part of permanent barrier because the hollow cable may provide a path for a fluid leak after abandonment.

If the location for a permanent barrier contains control cables, the practice today is to remove these by pulling out the whole production or injection tubing which the cables and cables are attached to. This requires a drill rig onsite, for example a floating drill rig. A problem with this is high time demands and cost, and sometimes safety issues.

Statement of invention

According to a first aspect of the inventon there is provided a method of preparing a well for subsequent plugging, the well comprising a casing, a tubular provided within the casing, and a cable provided between the casing and the tubular; the method comprising: providing within the tubular a means for cutting the tubular and the cable; cutting the tubular and the cable with said means along a helical path on the wall of the tubular in order to sever the cable at a plurality of locations while leaving the tubular substantially intact.

The means br cutting may be a wireline tool and may be an abrasive tool. For example, means for cutting may be one of thermal means, chemical means and mechanical means. Specifically, the means may comprises one of: thermite, explosives, a milling tool, a drilling tool, a computer numerical control, CNC, tool.

The step of cutting may comprise rotating the means for cutting around the longitudinal axis of the tubular and simultaneously moving the means for cutting along the longitudinal direction of the tubular. The step cutting the tubular may avoid severing the tubular.

According to a second aspect of the invention there is provided a method of removing part of a cable in a hydrocarbon well, the well comprising a casing, a tubular provided within the casing, and said cable provided between the casing and the tubular; the method comprising: severing the cable at one or more locations; providing within the tubular a means for cutting the tubular; farming an opening in the tubular in the vicinity of the cable; pulling a portion of the cable through the opening.

The method according to the second aspect may be followed by a step of lifting a portion of the cable through the tubular to the surface. The cutting means may be a wireline tool and may be a computer numerical control, CNC, tool. The cable may be located before cutting the opening in the tubular. The step of severing the cable may be carried out according to the first aspect of the invention.

According to a third aspect there is provided a method of preparing a well for subsequent plugging, the well comprising a casing, a tubular provided within the casing, and said cable provided between the casing and the tubular, wherein an annulus is provided between the tubular and the casing; the method comprising: filling the annulus with an insulating material for protecting the casing or a further tubular provided between the tubular and the casing; removing at least part of the tubular and the cable in the portion of the tubular where insulating material is provided by thermal energy, whilst leaving the casing or further tubular substantially undamaged.

The thermal energy may be provided by igniting thermite. The insulating material is provided in the entire annulus in the region where the tubular is removed. The insulating material may be one of resin and plastics. One or more holes may be formed in the tubular wall before placing the insulating material.

The method of any one of the first, second and third aspects of the invention may further comprising forming a plug in the region where the control cables have been severed. The method of any one of the first, second and third aspects of the invention may be repeated several limes along the tubular According to a fourth aspect of the invention there is provided apparatus for preparing a well for subsequent plugging, the well comprising a casing, a tubular provided within the casing, and a cable provided between the casing and the tubular. The apparatus comprises a cutting tool for insertion into the well for cutting the tubular aong a helical path on the wall of the tubular in order to sever the cable at a plurality of locations while leaving the tubular substantially intact.

Drawings Some embodiments of the invention will now be described by way of example only and with reference to the accompanying figures, in which: Fig. 1 illustrates schematically a tubular with a helical cut.

Fig. 2 is a flow diagram of a first method disclosed herein.

Fig. 3 illustrates schematically a tubular with a cut-out window.

Fig. 4 is a flow diagram of a second method disclosed herein Fig. 5 illustrates schematically a method of severing control.

Fig. 6 is a flow diagram of a third method disclosed herein.

Specific description

A hydrocarbon well considered herein includes at least one tubular extendng downhole and a casing which lines the formation. The casing protects the formation and strengthens the walls of the well. One or more control cables extend downhole for providing electricity or hydraulic power to downhole tools, or for carrying an optical signal or to send and receive control signals or measurements. The control cables are provided outside the tubular to avoid obstructions to fluid flow inside the tubular and to protect the control cables during use. If a well is permanently abandoned, a plug may be formed which seals the portion of the well below the plug from the portion of the well above the plug and thereby prevents hydrocarbons from escaping the abandoned well.

The presence of control cables extending through a plug may cause a leak to the plug.

The leak may be caused by deterioration of the material of the control cables over time or by hollow cables providing a path for a fluid leak or a leak path may be caused during manufacturing.

The control cables are provided outside the tubular, but within the casing. The control cables may be attached to the outside wall of the tubular by clamps or other fasteners.

The inventors have appreciated that the control cables need to be severed in at least a portion of the well region in which a plug is to be formed. The absence of control cables in at least a portion of the plug enables the formation of an effective plug whereby leaks are avoided. Besides the formation of plugs for abandonment of a well, plugs may be used when the well is extended sideways above the plug into a new part of the formation.

In a first embodiment, the cable is severed by providing within the tubular a means for cutting the tubular and the cable and by cutting the tubular and the cable with said means along a helical path on the waH of the tubular. The step of cutting may be achieved by rotating the means for cutting around the longitudinal axis of the tubular and simultaneously moving the means for cutting along the longitudinal direction of the tubular. The cutting means is provided within the tubular and the control cable is present outside the tubular. An advantage of this method of cuffing is that the exact location of the cable does not need to be known given that after the cuffing means has rotated around the longitudinal axis of the tubular by more than 360 degrees, the control cables will necessarily have been cut, provided that the cutting depth is sufficient.

The cuffing means may be a wireline tool, thereby avoiding the need of a drill rig. The cuffing means may be an abrasive tool such as a drill or milling tool. Other means for cuffing include thermal means such as thermite or by any energetic material, such as explosives, chemical means and mechanical means.

The helical cuffing path may include a plurality of windings such that the control cables are cut in a plurality of locations. An advantage of cuffing a helical path through the tubular wall is that the tubular itself is not severed and a lower portion of the tubular below the cut region will not drop down into the well.

Figure 1 illustrates a well with a casing 1, a tubular 2 extending within the casing and a control cable 3 provided between the tubular and the casing. An annular space is provided between the casing and the tubular. A wireline 4 is used to lower a tool 5 within the tubular 2. The tool 5 includes a cutting means for cutting a helical opening 6 into the tubular wall. A helical opening B may be formed at more than one location along the tubular. The cutting depth is chosen such that the cable 3 is cut at a plurality of locations 7, without damaging the casing 1. After severing the control cable, a plug is placed in the portion of the well where the helical opening 6 has been made.

Figure 2 is a flow diagram illustrating the steps of providing a means for cutting (Si) and making a helical cut in the tubular (S2) for severing the control cable.

The cable may be connected to the pipe wall by way of clamps and the clamps may automatically release after the cable has been severed. In a specific example, the spacing between the clamps is typically 10 to 12 meters and the helical cut may be made over a 1 meter interval on either side of a clamp or in between two clamps.

A method according to the second embodiment includes the method steps of providing within the tubular a means for cutting the tubular and the cable, cutting a window in the tubular wall using said means, accessing the cable through the window with a tool and attaching the cable to the tool and moving the cable through the window into the tubular. Before or after moving the cable through the window, the cable may be cut at one or more locations. The cut portion of the cable can be removed from the portion of the tubular with the window by lifting the cut portion towards the surface using the tool.

The cutting means may be a wireline tool. For example, the tool may be a computer numerical control, ONC, tool which is able to carry out multiple functions of cutting, grabbing and pulling. The tool may be a tool such as the one described in WO 2010/066276. A locating device may be used to locate the cable before cutting the window in the tubular wall.

Figure 3 illustrates a well with a casing 31, a tubular 32 extending within the casing and a control cable 33 provided between the tubular and the casing. The control cable is severed and is illustrated as extending into the tubular through a hole in the wall of the tubular. An annular space is provided between the casing and the tubular. A wireline 34 is used to lower a CNC tool 35 within the tubular 32. The tool 35 includes a cutting means for cutting an opening in the tubular wall, severing the cable, grabbing part of the severed cable and pulling part of the cable through the opening. The cable can be severed at a second place such that a portion of the cable can be lifted out of the well and there is a portion of the annulus Figure 4 is a flow diagram illustrating the steps of severing the cable at one or more locations (S4.1), providing within the tubular a means for cuffing the tubular (S4.2), forming an opening in the tubular was in the vicinity of the cable (S4.3), pulling a portion of the cable through the opening (S4.4).

The step of cutting the tubular and the cable may be carried out using the method of the first example using a helical cutting path.

A method according to the third embodiment includes the method steps of placing an insulating material between a portion of the tubular and the casing for protecting the casing and for preventing dispersion of the heat into the annulus, removing at least part of the tubular and the cable in the portion of the tubular where insulating material is provided. Heating means such as thermite or an explosion, or any other means of providing energy could be used to remove the portion of the tubular and control cable.

The insulating material will concentrate the heat and potentially protect the casing of the well against the heat and explosive forces. The insulating material is preferably provided around the entire perimeter of the tubular in the region where the tubular is removed. The insulating material is one of resin and plastics. Before the insulating material is placed around the tubular, holes may be formed in the tubular such that the insulating material can be placed from within the tubular.

Figure 5 illustrates a well with a plurality of tubulars 51, 52, 53, 54, 55. In this specific example, the inner tubular 55 is surrounded by another tubular 53, but the inner tubular may also be surrounded by a casing as in the first and second examples discussed before. A cable 56 extends downwards between the outside of tubular 55 and tubular 53. Before forming a plug across the inner diameter of tubular 53, an insulating material is provided which fills the annulus between tubular 53 and tubular 55 for protecting tubular 53. Before placing the insulating material, holes may be punched in tubular 55 to place the material into the annulus from the inside of tubular 55. After placing the insulating material 57, a heating means 58 is lowered with a wireline 59.

The heating means may be thermite. The thermite can be ignited once in place and then it will melt a portion of tubular 55 and cable 56, while tubular 53 is protected against the heat by insulator 57. The melted material may become part of the permanent plug. A further advantage of the insulating material is that the heat generated by the heating means is used more efficiently as the insulating material reduces dispersion of the heat. Examples of insulating materials are resin or other plastics. Part of the plastics may also be melted by the heating means while still carrying out its protective function.

Figure 6 is a flow diagram illustrating the steps of plaoing an insulator in the annulus (86.1), providing means for heating the inner tubular (86.2) and severing the control cable and tubular using the heating means (86.3).

The methods described above for severing a cable and removing part of the tubular may be repeated at a plurality of locations along the length of the tubular. A plurality of plugs can be formed after the cable has been severed.

Although the invention has been described in terms of preferred embodiments as set forth above, it should be understood that these embodiments are illustrative only and that the claims are not limited to those embodiments. Those skilled in the art will be able to make modifications and alternatives in view of the disclosure which are contemplated as falling within the scope of the appended claims. Each feature disclosed or illustrated in the present specification may be incorporated in the invention, whether alone or in any appropriate combination with any other feature disclosed or illustrated herein.

Claims

CLAIMS: 1. A method of preparing a well for subsequent plugging, the well comprising a casing, a tubular provided within the casing, and a cable provided between the casing and the tubular; the method comprising: providing within the tubular a means for cutting the tubular and the cable; cutting the tubular and the cable with said means along a helica path on the wall of the tubular in order to sever the cable at a plurality of locations while leaving the tubular substantially intact.
2. The method according to claim 1, wherein the means for cutting is a wireline tool.
3. The method according to claim 1 or 2, wherein the means for cutting is an abrasive tool.
4. The method according to claim 1 or 2, wherein the means for cutting comprises one of thermal means, chemical means and mechanical means.
5. The method according to claim 1 or 2, wherein the means comprises one of: thermite, explosives, a milling tool, a drilling tool, a computer numerical control, CNC, tool.
6. The method according to claim 1 or 2, wherein the step of cutting comprises rotating the means for cutting around the longitudinal axis of the tubular and simultaneously moving the means for cutting along the longitudinal direction of the tubular.
7. The method according to any one of the preceding claims, wherein cutting the tubular does not sever the tubular.
8. A method of removing part of a cable in a hydrocarbon well, the well comprising a casing, a tubular provided within the casing, and said cable provided between the casing and the tubular; the method comprising: severing the cable at one or more locations; providing within the tubular a means for cutting the tubular; forming an opening in the tubular in the vicinity of the cable; pulling a portion of the cable through the opening.
9. The method of claim 8, further comprising lifting a portion of the cable through the tubular to the surface.
10. The method of claim 8 or 9, wherein the cutting means is a wireline tool.
11. The method of any one of claims 8 to 10, wherein the cutting means is a computer numerical control, CNC, tool.
12. The method of any one of claims 8 to 11, further comprising locating the cable before cutting the opening in the tubular.
13. The method of claim 8, wherein said step of severing the cable is carried out according to the method of claim 1.
14. A method of preparing a well for subsequent plugging, the well comprising a casing, a tubular provided within the casing, and said cable provided between the casing and the tubular, wherein an annulus is provided between the tubular and the casing; the method comprising: filling the annulus with an insulating material for protecting the casing or a further tubular provided between the tubular and the casing; removing at least part of the tubular and the cable in the portion of the tubular where insulating material is provided by thermal energy, whilst leaving the casing or further tubular substantially undamaged.
15. The method of claim 14, wherein said thermal energy is provided by igniting therm ite.
16. The method of claim 14 or 15, wherein said insulating material is provided in the entire annulus in the region where the tubular is removed.
17. The method of any one of claims 14 to 16, wherein said insulating material is one of resin and plastics.
18. The method ci any one of claims 14 to 17, further comprising creating one or more holes in the tubular wall before placing the insulating material.
19. The method of any one of the preceding claims, further comprising forming a plug in the region where the control cables have been severed.
20. The method of any one of the preceding claims, comprising repeating said method at a plurality of locations along the tubular.
21. Apparatus for preparing a well for subsequent plugging, the well comprising a casing, a tubular provided within the casing, and a cable provided between the casing and the tubular; the apparatus comprising: a cutting tool for insertion into the well for cutting the tubular along a helical path on the wall of the tubular in order to sever the cable at a plurality of locations while leaving the tubular substantially intact.