GB2356679A

GB2356679A - Utilising an old pipeline to house cables and/or narrower pipelines

Info

Publication number: GB2356679A
Application number: GB0022435A
Authority: GB
Inventors: Stuart Mcintyre
Original assignee: Boreas Consultants Ltd
Current assignee: Boreas Consultants Ltd
Priority date: 1999-09-14
Filing date: 2000-09-13
Publication date: 2001-05-30
Anticipated expiration: 2020-09-13
Also published as: GB0022435D0; GB2356679B; GB9921608D0

Description

lot 940 2356679

I APPARATUS AND METHOD FOR RECLAIMING PIPELINES 2 3 This invention lies in the field of pipeline engineering 4 and relates to apparatus and method for reclaiming 5 otherwise inefficient or even redundant pipelines. The 6 invention finds a particular but not exclusive 7 application in the re-use of oil pipelines. 8 9 It is recognised that there are a large number of 10 pipelines that by reason of age, corrosion or changing 11 commercial circumstances have degraded into a state of 12 inefficiency, low integrity or general disrepair. 13 Pipelines laid at one time to export oil have had to be 14 abandoned and replaced by larger pipelines to meet 15 changing demands. These original pipelines now lie full 16 of seawater. 17 18 Other pipelines, once required to export large amounts of 19 oil, are now no longer required or carry low volumes due 20 to the maturing of sites. In such circumstances, it has 21 heretofore been uneconomical to either replace these 22 pipelines or perform the necessary maintenance to keep 23 them fully operational. On the other hand, prohibitive 24 abandonment costs make it a preferable option for

2 1 operators to continue to use such pipelines for as long 2 as possible, even though inefficient.

3 4 There is, nonetheless, a drive within the oil industry to develop methods for exhausting reservoirs so as to extend 6 the life of these oilfields. With this, comes the desire

7 to prolong the use of pipelines and the ability to 8 economically maintain their integrity. Such action is 9 also attractive due to the increasing scrutiny to which the activities of oil companies are subjected by 11 environmental groups and agencies. Indeed, the disposal 12 of all installations that have exceeded their useful 13 working life is carefully monitored. For example, the 14 decommissioning of the Brent Spar rig was the subject of much debate.

16 17 Furthermore, in the years to come it is likely there will 18 be a burgeoning network of unused pipelines on the 19 seabed. These pipelines will inevitably be in such poor condition that further use in oil exploration will not be 21 possible.

22 23 It would therefore be desirable to develop alternative 24 uses for pipelines that are not of a sufficient standard to be used as a main pipeline for oil export from the 26 oilfield to the shore.

27 28 Alternative methods of using existing pipelines could 29 provide a number of benefits. For example, the lifetime of existing fields could be extended, the pipelines could

31 provide a casing for other cables such as power cables 32 and the pipelines could be used as part of offshore 33 windfarms.

34 3 1 It is an object of the present invention to provide a 2 method of using old pipelines that would otherwise be 3 abandoned at considerable cost.

4 It is a further object of the present invention to 6 provide an economical means of rejuvenating mature 7 pipelines assets in parallel with advancing reservoir 8 recovery technology, which is extending the life of 9 oilfields, but where the flows are not sufficient to justify a new pipeline.

11 12 According to a first aspect of the present invention 13 there is provided a method of reclaiming an existing 14 pipeline that has ceased being used for its original function, the method comprising the assembly of one or 16 more smaller diameter pipelines or cables on a bundle and 17 thereafter installing the bundle into the existing 18 pipeline.

19 The installation of the bundle may be performed using 21 vehicles adapted to install the bundle as it travels 22 through the existing pipeline.

23 24 Preferably there is a series of co-ordinated vehicles used for installation.

26 27 Preferably the vehicles pull the bundle through the 28 pipeline.

29 Alternatively the vehicles push the bundle through the 31 pipeline.

32 33 Most preferably the vehicles pull and push the bundle 34 through the pipeline.

4 2 Preferably the vehicles that are used to install the 3 bundle in a pipeline are tractors. 4 5 Alternatively the vehicles that are used to install the 6 bundle in a pipeline are pipeline pigs. 7 8 Preferably the installation of a bundle into a pipeline 9 is controlled from a remote centre. 10 11 optionally the bundle can incorporate a number of 12 pipelines or cables each with a different application. 13 14 optionally the pipelines or cables in a bundle can be 15 provided in a number of lengths which will be attached 16 together during the installation process. 17 18 The method may be reversed for the purposes of 19 abandonment of the pipeline. 20 21 Optionally, the vehicles that are used to install the 22 bundle of pipelines and cables are able to use any power 23 cables that are being installed to provide their own 24 power. 25 26 According to a second aspect of the present invention 27 there is provided a method of using an existing pipeline 28 that has ceased being used or suitable for its original 29 function, the method comprising the use of the pipeline 30 as a protective conduit for one or more service cables or 31 pipelines located within the existing pipeline. 32 33 According to a third aspect of the present invention 34 there is provided a first pipeline acting as a protective 1 conduit for one or more service cables and smaller 2 diameter pipelines.

3 4 The first pipeline may typically be a pipeline that is not in an appropriate condition to act as a means of 6 transmitting oil or other fluid. Alternatively, the 7 first pipeline may be located in a manner that renders it 8 otherwise wholly or partially obsolete due to the 9 maturing status of an oil reservoir or other site with which it is associated.

11 12 The one or more service cables may comprise of power 13 cables or fibre-optics for communication or other 14 purposes, for example.

16 Optionally, the smaller diameter pipelines may be used 17 for the transmission of oil or gas.

18 19 Preferably, the first pipeline acts as a pipe bridge over spanning sections of the inner cables or smaller diameter 21 pipelines.

22 23 Typically, the first pipeline is a subsea pipeline.

24 In order to provide a better understanding of the 26 invention, an example embodiment and method will now be 27 described with reference to the accompanying sole Figure 28 which illustrates an existing pipeline adapted for use in 29 an alternative manner to its original function.

31 Referring to the Figure, a pipeline that may have fallen 32 into disrepair or that is no longer suitable or required 33 for its original purpose, is generally depicted at 10.

34 Contained within the pipeline 10 there is provided a 6 1 bundle 3 supported on the pipeline lining 2 by rollers 4.

2 The bundle 3 in this example is comprised of both cables 3 and smaller diameter pipelines, although it should be 4 appreciated that the present invention allows for the bundle to comprise merely of only one internal cable or 6 pipeline or any number or combination of such that might 7 reasonably contained within the limitations of an 8 existing pipeline. The bundle 3 in the Figure is adapted 9 to hold a gas pipe 5, a power and control cable 6, a high tension power cable 7, an oil export pipeline 8 and a 11 power cable for a control system 9.

12 13 It may be seen that the pipeline 10 acts as a protective 14 sheath around the multipurpose bundle 3. Notwithstanding any diminished integrity of the pipeline 10, it is almost 16 inconceivable that the bundle 3 could be damaged by 17 external forces as a result. One further advantage of 18 this lies in the fact that stringent external inspection 19 of the cable/pipeline bundle is negated.

21 Typically, for installation in a subsea pipeline, the 22 bundle 3 of cables and pipelines would be assembled on 23 the beach as its installation proceeded. This would mean 24 that the only bends that must be negotiated during the installation process would be those resulting from the 26 pipeline elastically conforming to the sea bed profile, 27 and to changes in direction in the installation vessel.

28 Tractors, sited at regular intervals within the pipeline, 29 would be able to effect the installation of the bundle.

The tractors used may be similar to those used for down- 31 hole operations. The tractors could also be used to 32 uninstall the bundle.

33 7 1 Alternatively, or additionally, injectors or other 2 apparatus may be used to push the bundle or individual 3 cables or tubing into the pipeline. It will be 4 appreciated by those skilled in the art that certain contours of pipeline will be more efficiently negotiated 6 by pushing rather than pulling the bundle and there may 7 be advantage in having the bundle provided with both 8 pushing and pulling apparatus simultaneously.

9 The installation of the bundle would be controlled from a 11 remote centre.

12 13 For shorter installation lengths, or where limited number 14 of applications are to be installed, a series of pipeline pigs can be used as a replacement for the tractors, whose 16 use would not be economic.

17 18 In order to make the installation as economical as 19 possible, if power cables are being installed into the pipeline they can be used to supply power to the 21 installation vehicles.

22 23 An advantage of the present invention is that it allows 24 existing pipeline to be used a protective conduit for a variety of service cables or as a low integrity flowpath.

26 Accordingly, pipelines having a diminished utility may be 27 adapted to support a number of new and multi-purpose 28 functions.

29 Furthermore, new service cables or pipelines can be 31 readily installed with negligible environmental impact.

32 Installation of the bundle would also not be affected by 33 changes in the weather and thus winter operations would 34 be possible.

8 2 The use of the pipeline allows for the use of coiled 3 tubing that might otherwise be considered too light and 4 unstable to seabed currents.

6 The cost of abandonment is also deferred due to the 7 further uses of the pipeline. These costs can be quite 8 considerable.

9 It may also be possible that oilrigs that would otherwise 11 be de-commissioned could be used as offshore wind farms 12 with the power generated being conducted onshore using 13 the pipeline that would otherwise fall out of use.

14 Further modifications and improvements may be made 16 without departing from the scope of the invention herein 17 intended.

18 19 20 21 9

Claims

1 Claims 2 3 1. A method of reclaiming an existing pipeline that has

4 ceased being used for its original function, the method 5 comprising the assembly of one or more smaller diameter 6 pipelines or cables on a bundle and thereafter 7 installing the bundle into the existing pipeline. 8 9

2. A method of reclaiming an existing pipeline as in Claim 1, wherein installation of a bundle of pipelines or 11 cables is performed using a vehicle adapted to install 12 the bundle as it travels through the pipeline.

13 14

3. A method of reclaiming an existing pipeline as in Claim 1 or Claim 2, wherein a series of co-ordinated vehicles 16 are used to install the bundle.

17 18

4. A method of reclaiming an existing pipeline as in 19 Claims 1 to 3, wherein vehicles are used to pull the bundle into the pipeline.

21 22

5. A method of reclaiming an existing pipeline as in 23 Claims 1 to 3, wherein vehicles are used to push the 24 bundle into the pipeline.

26

6. A method of reclaiming an existing pipeline as in 27 Claims 1 to 3, wherein a series of co-ordinated 28 vehicles are used to both push and pull the bundle as 29 it is installed into the pipeline.

31

7. A method of reclaiming an existing pipeline as in any 32 of the previous Claims wherein the vehicles that are 33 used for installing the bundle into the pipeline are 34 tractors.

1 2

8. A method of reclaiming an existing pipeline as in any 3 of the previous Claims wherein the vehicles that are 4 used for pulling the bundle through the pipeline are pipeline pigs.

6 7

9. A method of reclaiming an existing pipeline as in any 8 of the previous Claims wherein the installation of a 9 bundle is controlled from a remote centre.

11

10. A method of reclaiming an existing pipeline as in 12 any of the previous Claims, wherein the bundle of one 13 or more smaller diameter pipelines or cables may be fed 14 through the pipeline in a number of lengths which are 15 joined together. 16 17

11. A method of reclaiming an existing pipeline as in 18 any of the previous Claims wherein the vehicles that 19 are used for pulling the bundle through the pipeline 20 are able to use power cables in the bundle to supply 21 their power. 22 23

12. A pipeline acting as a protective conduit for a 24 bundle of one or more service cables and smaller 25 diameter pipelines, wherein the bundles have been 26 installed into the pipeline using the method described 27 in any of Claims 1 to 8. 28 29

13. A series of remotely controlled vehicles for use in installing a bundle of one or more service cables and 31 smaller diameter pipelines into an existing pipeline.

32 33

14. A series of remotely controlled vehicles as 34 described in Claim 10 wherein the vehicles work co- 11 I operatively to transport a bundle through an existing 2 pipe without the bundle breaking.

3 4

15. A series of remotely controlled vehicles as Claimed in Claims 10 or 11, wherein the vehicles for 6 transporting receive power via the power cables they 7 are transporting.