Method of plugging a well

Abstract

A method of plugging a well in a plug and abandonment procedure includes providing a tubing in a wellbore, in a location for a well plug, the tubing is provided with an internal cable section placed inside of the tubing, and forming a plug in the well in said location for the well plug across the width of the tubing and a surrounding wellbore annulus to create a permanent barrier without pulling the tubing from the wellbore. The step of forming the plug includes substantially removing the internal cable section inside the tubing and forming a fluid-tight seal in the tubing where the internal cable section has been removed, for separating, on either side of the seal, first and second fluid volumes of the tubing.

Claims

1. A method of plugging a well in a plug and abandonment procedure, comprising: providing a tubing in a wellbore, wherein in a location for a well plug, the tubing is provided with an internal cable section placed inside of the tubing and said tubing is an innermost tubing in the wellbore; and forming a plug in the well in said location for the well plug across the width of the tubing and a surrounding wellbore annulus to create a permanent barrier without pulling the tubing from the wellbore, wherein said step of forming the plug comprises substantially removing the internal cable section inside the tubing and forming a fluid-tight seal in the tubing where the internal cable section has been removed, for separating, on either side of the seal, first and second fluid volumes of the tubing.

2. The method according to claim 1 wherein the step of providing the tubing in the wellbore is implemented during completion of a new well or during re-completion of an old well.

3. The method according to claim 1 wherein the internal cable is configured as an electrical control cable, a hydraulic line, a fiber optic cable or a support cable.

4. The method according to claim 1 wherein a plurality of internal cables are provided inside of the tubing, in the location for the well plug.

5. The method according to claim 1 where the step of removing the internal cable section inside the tubing comprises cutting, milling, dissolving or otherwise destroying the internal cable section to ensure that there is no fluid flow path through the internal cable in the location for the well plug.

6. The method according to claim 1 wherein the step of providing a tubing in a wellbore with a section of internal cable placed inside the tubing in said location for the well plug comprises providing a tubing having a further section of cable placed outside the tubing and a port through which the further section of cable transitions from the outside of the tubing to the inside of the tubing to connect with said section of internal cable placed inside the tubing.

7. The method according to claim 1 wherein the step of forming the plug in the well comprises creating a hole in the tubing in the location for the well plug and introducing plugging material into the wellbore and through the hole.

8. The method according to claim 7 wherein a temporary plug is provided in the tubing below the location of the hole so as to form a shelf or ledge on which the plugging material within the tubing may set.

9. The method according to claim 1 comprising forming multiple plugs in the wellbore at a number of locations configured for such well plugs.

10. A method of plugging a well in a plug and abandonment procedure, comprising: providing a tubing in a wellbore, wherein in a location for a well plug, the tubing is provided with an internal cable section placed inside of the tubing; and forming a plug in the well in said location for the well plug across the width of the tubing and a surrounding wellbore annulus to create a permanent barrier without pulling the tubing from the wellbore, wherein said step of forming the plug comprises substantially removing the internal cable section inside the tubing and forming a fluid-tight seal in the tubing where the internal cable section has been removed, for separating, on either side of the seal, first and second fluid volumes of the tubing, wherein in the location for the well plug, the tubing is provided with an external cable section placed outside of the tubing, the external cable section comprising a fluid-tight cable suitable for forming a sealing part of the well plug.

11. The method according to claim 10 wherein the step of forming a plug in the well comprises: forming a fluid-tight seal in a wellbore annulus surrounding the tubing, with the external cable section forming a part of the seal, for separating, either side of the seal, first and second fluid volumes of the wellbore annulus.

12. The method according to claim 10 wherein the fluid-tight external cable is designed and manufactured in such a way that no internal voids exist in the cable.

13. The method according to claim 10 wherein the step of forming a plug in the well comprises sealing any interior cavities in the external cable.

14. The method according to claim 10 wherein the fluid-tight external cable has an external surface which will not degrade under wellbore conditions to cause a leak path through the well plug and that will readily seal with the material forming the plug.

15. The method according to claim 14 wherein the external surface is provided by a coating layer.

16. The method according to claim 10 wherein the external cable is configured as an electrical control cable, a hydraulic line, a fiber optic cable or a support cable.

17. The method according to claim 10 wherein a plurality of external cables are provided outside of the tubing, in the location for the well plug.

18. The method according to claim 17 comprising sealing all of the external cables provided outside of the tubing.

19. The method according to claim 10 wherein the fluid-tight external cable comprises one or more of the following: non-braided wire; gas-tight construction; continuous conductive screen; ceramic, porcelain, glass, mineral or composite type coating; and electric wire.

20. A method of performing a wellbore operation, comprising: providing a tubing in a wellbore, wherein in a location for forming a well plug across the width of the tubing and a surrounding wellbore annulus to create a permanent barrier, the tubing is provided with an internal cable section placed inside of the tubing and the tubing is an innermost tubing in the wellbore; and using the tubing in a wellbore operation, wherein said using comprises substantially removing the internal cable section inside the tubing and forming a fluid-tight seal in the tubing where the internal cable section has been removed, for separating, on either side of the seal, first and second fluid volumes of the tubing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Specific embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

(2) FIG. 1a shows a longitudinal cross-sectional view of a wellbore provided with tubing having an external electrical control cable section placed outside of the tubing in accordance with a first embodiment of the invention;

(3) FIG. 1b shows the wellbore of FIG. 1a after a section of the tubing has been removed during a plugging procedure;

(4) FIG. 1c shows the wellbore of FIG. 1b after cement has been injected through the tubing to form a plug across the width of the wellbore;

(5) FIG. 2a shows a view similar to that of FIG. 1a but wherein the tubing further comprises an internal fluid cable section placed inside the tubing, in accordance with a second embodiment of the invention;

(6) FIG. 2b shows the wellbore of FIG. 2a after the inner fluid cable section has been removed;

(7) FIG. 2c shows the wellbore of FIG. 2b after the a hole has been created in the tubing in the location for the well plug; and

(8) FIG. 2d shows the wellbore of FIG. 2c after plugging material has been introduced into the wellbore, to form a plug across the width of the tubing and surrounding annulus.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

(9) With reference to FIGS. 1a, b and c, there is illustrated a method for plugging a well in accordance with a first embodiment of the present invention. The method comprises providing a production tubing 10 in a wellbore 12, the tubing 10 being provided with a (standard) electrical control cable 14 along the outside of the tubing 10 but wherein, in a location for a well plug, the tubing 10 is provided with an external electrical control cable section 14 (also placed outside of the tubing 10), the electrical control cable section 14 comprising a fluid-tight electrical cable 16 suitable for forming a sealing part of a well plug. In this embodiment, the fluid-tight electrical cable 16 comprises a ceramic coating.

(10) In particular embodiments, the fluid-tight electrical cable 16 may have a length of between 60 m and 200 m. However, it be understood that the required length will depend upon the desired length of the well plug to be formed around the fluid-tight electrical cable 16 and the accuracy of the procedures for providing the fluid-tight electrical cable 16 in the location for the well plug. In other embodiments, the (standard) electrical control cables 14 may be replaced with fluid-tight electrical cable 16 so that a well plug can be placed at any location along the length of the tubing.

(11) As illustrated, a production packer 18 is provided in an annulus 20 surrounding the tubing 10, at or close to a lowermost region of the location for the well plug. A hole 22 is milled in the tubing 10, above the production packer 18, and a plugging material 24 (e.g. comprising cement) is introduced through the tubing 10 so as to form a well plug 26 in the tubing 10 and the annulus 20, in the location for the well plug. Accordingly, the plugging material 24 will encapsulate and seal against the tubing 10 and the fluid-tight electrical cable 16 in the location for the well plug 26.

(12) Although not shown, a temporary plug may be provided in the tubing 10 below the location of the hole 22 so as to form a shelf or ledge on which the plugging material 24 within the tubing 10 may set.

(13) It will be understood that, in practice, the tubing 10 will be provided within one or more outer casings 28 which are cemented in place. It may therefore be necessary to check that the outer casing cement 30 is properly placed and verified as a permanent barrier.

(14) FIGS. 2a, b, c and d illustrate a method for plugging a well in accordance with a second embodiment of the present invention. This method is similar to that described above in relation to FIGS. 1a through 1c and so like reference numerals will be employed. In this embodiment the tubing 10 is further provided with a (standard) fluid line 32 provided on the outside of the tubing 10 but wherein, in a location for a well plug, the tubing 10 is provided with a fluid cable section 34 placed inside of the tubing 10. For example, the fluid cable section 32 may be constituted by a hollow hydraulic line or a hollow injection line. The outer (standard) fluid line 32 is fluidly connected to the inner fluid cable section 34 through entry and exit transition ports 36, which are provided in the tubing 10. The transition ports 36 are configured to form a fluid-tight seal with the tubing 10.

(15) As illustrated in FIG. 2b, the provision of the fluid cable section 34 inside the tubing 10 permits access to the hollow line so that it can be milled out in the location of the well plug thereby removing a potential fluid flow path through the plug.

(16) Once the fluid cable section 34 has been removed, the method proceeds as described above. This, FIGS. 2c and 2d show the production packer 18 provided in the annulus 20 surrounding the tubing 10 and a hole 22 milled in the tubing 10, above the production packer 18, for introduction of the plugging material 24. As before, the plugging material 24 encapsulates and seal against the tubing 10 and the fluid-tight electrical cable 16 in the location for the well plug 26.

(17) Aspects of the invention therefore relate to the installation of control cables and lines during completion of a new well or re-completion of an old well, which can form a part of a permanent barrier, thereby minimising the time, cost and safety concerns associated with traditional plug and abandonment techniques.

(18) It will be appreciated by persons skilled in the art that various modifications may be made to the above-described embodiments without departing from the scope of the present invention, as defined by the claims.