WO2011151421A1

WO2011151421A1 - Apparatus for sealing to a broken pipe and method for sealing such an apparatus to such a broken pipe

Info

Publication number: WO2011151421A1
Application number: PCT/EP2011/059154
Authority: WO
Inventors: William George Clark
Original assignee: Statoil Asa
Priority date: 2010-06-03
Filing date: 2011-06-01
Publication date: 2011-12-08

Abstract

A method and apparatus for sealing to a broken pipe conveying a first fluid under pressure. The apparatus comprises a first chamber for a pressurisable second fluid, a second chamber for a pressurisable third fluid, a first seal which is moveable from a first position, in which the first seal is free of the broken pipe during engagement of the apparatus with the broken pipe, to a second position in which, following the engagement, the first seal is in sealing and frictional contact with the broken pipe in response to an increased second fluid pressure in the first chamber, and a first connector for connecting the chamber to a source of pressurised the second fluid. A second seal and connector is also provided.

Description

Apparatus for Sealing to a Broken Pipe and Method for Sealing Such an

Apparatus to such a Broken Pipe

Technical Field

The present invention relates to an apparatus for sealing to a broken pipe conveying a first fluid under pressure. The present invention also relates to a method of sealing such an apparatus to such a broken pipe. Such methods and apparatuses may be used, for example, in order to stop or reduce the spillage of hydrocarbons, such as crude oil, from an undersea pipe conveying production fluid, for example from an underwater oil well.

Background Pipes conveying fluid under pressure, such as production pipes for oil wells, can break. When this occurs in a hostile environment, for example, on a sea bed , it can be extremely difficult to stop the fluid from escaping.

Summary

According to a first aspect of the invention, there is provided an apparatus for sealing to a broken pipe conveying a first fluid under pressure, said apparatus comprising: a first chamber for a pressurisable second fluid and a second chamber for a pressurisable third fluid. A first seal is provided which is moveable from a first position, in which the first seal is free of the broken pipe during engagement of said apparatus with said broken pipe, to a second position, in which, following said engagement, the first seal is in frictional and sealing contact with the broken pipe in response to an increased second fluid pressure in the first chamber; and a first connector for connecting said chamber to a source of pressurised second fluid. A second seal is also provided, which is moveable from a first position, in which the second seal is free of the broken pipe during engagement of said apparatus with said broken pipe, to a second position, in which, following said engagement, the second seal is in frictional and sealing contact with the broken pipe in response to an increased third fluid pressure in the second chamber; and a second connector for connecting the second chamber to a source of pressurised second fluid Said apparatus may be insertable into an end of said broken pipe when the seals are in the first position. Alternatively, an end of said broken pipe may be insertable into said apparatus when the seals are in said first position.

Said apparatus may further comprise a rigid body the seals and chambers may be disposed between said broken pipe and said rigid body following said engagement. Said rigid body may comprise an outlet pipe for said first fluid from said broken pipe. Said outlet pipe may be connected to one of a control valve, a shut-off valve and a riser.

At least one seal may comprise an annular seal.

At least one seal may be biased towards said first position.

At least one seal may comprise a torridal rubber seal defining an inner volume in fluid communication with said chamber.

At least one seal may comprise a resilient membrane. Said membrane may be made of stainless steel. The membrane may comprise a coating which increases friction between the membrane and the broken pipe when the membrane is engaged with the broken pipe. The membrane may additionally or alternatively be provided with a textured surface, such as knurling, in order to increases friction between the membrane and the broken pipe when the membrane is engaged with the broken pipe.

Said apparatus may further comprise at least one friction pig which is moveable from a th ird position , in which said friction pig is free of said broken pipe during said engagement, to a fourth position, in which said friction pig is in frictional engagement with said broken pipe following said engagement. Each said at least one friction pig may comprise a piston disposed in a cylinder in fluid communication with said chamber.

A surface of the friction pig arranged to be in engagement with the broken pipe may be coated or textured to improve grip by increasing friction between the surface of the friction pig and the broken pipe. Any of the connectors may be connected to a non-return valve for non-return of said second or third fluid to said source. Any of the second fluid and third fluid may be one of hydraulic and pneumatic fluid.

Said broken pipe may be for conveying production fluid from a well. Said production fluid may be a hydrocarbon. According to a second aspect of the invention, there is provided a method of sealing an apparatus according to the first aspect of the invention to a broken pipe, said method comprising the steps of: deploying said apparatus with said seals in said first position; engaging said apparatus with said broken pipe; and increasing said second fluid and third fluid pressure in said first and second chambers such that said at least one seal is in frictional and sealing contact with said broken pipe.

Said broken pipe may be an underwater pipe and said engaging step may comprise manoeuvring said apparatus with a remotely operated vehicle. Said method may comprise the subsequent step of reducing an outflow of said first fluid.

It is thus possible to provide an apparatus and a method which may be used in situations relating to the breakage or leakage of oil delivery pipes or systems. For example, such techniques may be used to close or at least temporarily repair pipes in oil wells in an emergency, until other more permanent solutions may be effected. Such techniques may also be used to provide a relatively immediate repair of broken pipes which will need to be reconnected after such breakage. Brief Description of the Drawings

Figure 1 illustrates the use of a method constituting an embodiment of the invention to seal an apparatus constituting an embodiment of the invention to a broken oil pipe on the seabed; Figure 2 is a cross-sectional view of an apparatus constituting a further embodiment of the invention;

Figure 3 is a cross-sectional view of an apparatus constituting another embodiment of the invention;

Figure 4 is a cross-sectional view of an apparatus constituting yet another embodiment of the invention; and Figure 5 further illustrates the use of a method to seal an apparatus to a broken oil pipe on the sea bed.

Detailed Description Figure 1 illustrates a broken oil pipe 1 disposed on the seabed 2 and comprising, for example, an oil delivery pipe from a subsea oil well. In the case of such a broken oil pipe, crude oil from the well may escape into the environment and it may not be possible to control the flow of such crude oil. An apparatus in the form of a plug 3 is shown during deployment in order to attempt to seal the broken pipe so as to prevent or reduce further oil spillage.

During deployment, the apparatus 3 is manoeuvred into position so as to be inserted into the broken or ruptured oil pipe 1 . In such a hazardous situation, the apparatus is typically manoeuvred and inserted using a remotely operated vehicle (ROV; not shown). The apparatus 3 is connected by an hydraulic or pneumatic pipe or line 4 to a vessel 5 floating on the surface 6 of the sea. When the apparatus has been inserted into the end of the broken pipe 1 , hydraulic or pneumatic pressure generated by a source in the vessel 5 is conveyed to the apparatus 3 so as to fix the apparatus within the pipe by friction and so as to seal the end of the pipe to prevent or at least reduce further spillage. The hydraulic or pneumatic pressure source in the vessel 5 maintains the hydraulic or pneumatic pressure so as to retain the apparatus 3 within the pipe 1 until a more permanent solution to the problem may be deployed.

In Figure 1 , the apparatus 3 is shown as a plug for closing the end of the pipe 1 in order to prevent or reduce further outflow from the pipe 1 . However, the apparatus 3 may include an outlet oil pipe 7 and an apparatus of this type is shown in Figure 2. The outlet pipe 7 forms part of a rigid body for insertion into the end of the pipe 1 . The outlet pipe 7 is disposed inside and coaxially with a tube 8, forming another part of the rigid body, to define therebetween an annular chamber 9 whose ends are sealed by means of seals 10 and 1 1 . Annular inflatable rubber seals 12 are provided in annular grooves formed in rigid metal bodies 13 around the tube 8. The inflatable rubber seals 12 are toroidal and have inner volumes which communicate via aligned apertures 14 and 15 with the chamber 9. Metallic friction pigs 16 are provided in the form of pistons disposed within cylinders defined in annular metal bodies 17 around the tube 8. The cylinders communicate with the chamber 9 via apertures 18. The frictions pigs 16 provide additional grip to the surface of the outlet oil pipe 7, which ensures that the apparatus is firmly secured to the outlet oil pipe. Note that each friction pig 16 may have a pointed end or a blunt end to secure it to the outlet oil pipe 7. A blunt end may be used where there is a risk that a pointed end would further damage the outlet oil pipe 7. The surface of the friction pig 16 that contacts the outlet oil pipe 7 may be provided with a texture such as knurling, or a coating. Texturing or coating the surface of the friction pig 16 in contact with the outlet oil pipe 7 increases the friction and therefore increases the strength of the sealing of the apparatus to the outlet oil pipe 7. Examples of coatings include thermal coatings such as metals or ceramics. Tungsten carbide is particularly suitable. The coating is applied using any conventional application means, for example spraying or plasma spraying. Another example of a coating is a dispersion of a hard particulate material such as tungsten carbide in a carrier material such as an epoxy resin. Various types of coating are suitable, provided that they have the effect of increasing the friction between the thin wall metal tube 20 and a surface of the outlet oil pipe 7.

A connection 23 is provided so as to connect the hydraulic or pneumatic line 4 to the chamber 9 such that the hydraulic or pneumatic pressure provided by the source in the vessel 5 is transmitted to the chamber so as to act on the inflatable seals 12 and the friction pigs 16. The dimensions of the apparatus 3 are such that it may be freely inserted into the end of the broken pipe 1 during deployment. During such deployment, the hydraulic or pneumatic pressure in the chamber 9 is such that the inflatable seals 12 are substantially uninflated so that their outer annular surfaces are retracted into the grooves in the bodies 13 (in a "first" position). Similarly, the pistons formed by the friction pigs 16 are fully retracted inside the cylinders in the bodies 17 so as not to protrude therefrom (in a "third" position).

When the apparatus 3 has been manoeuvred into position inside the end of the broken pipe 1 , the source in the vessel 5 increases the hydraulic or pneumatic pressure, which is transmitted via the line 4 to the chamber 9. The inflatable flexible rubber seals 12 are thus inflated so that the outer surfaces of the seals 12 are pressed against the inside wall of the pipe 1 (in a "second" position). Similarly, the increased pressure supplied to the cylinders in the bodies 17 pushes the metallic friction pigs 16 radially outwardly so as to engage the inside wall of the pipe 1 (in a "fourth" position). The combination of the increased pressure and the friction provided by the seals 12 and the pigs 16 is such as to provide a friction contact between the apparatus 3 and the broken pipe 1 which is sufficient to hold the apparatus 3 inside the pipe 1 against the pressure of the oil within the pipe. The seals 12 are pressed against the inner wall of the pipe 1 with sufficient pressure so as to form a seal which prevents or reduces the spillage of oil between the apparatus 3 and the pipe 1 into the sea.

In order for the apparatus 3 to work, it must be "fully" inserted into the pipe 1 before the pressure in the chamber 9 is increased. In particular, it must be inserted such that all of the seals 12 engage the inner surface of the pipe 1 when in the second position. The pigs 16 may be provided with stops to prevent them from being expelled from the cylinders, with resulting loss of pressure in the chamber 9, as the pressure is increased. For maximum effectiveness, the apparatus should be inserted into the pipe sufficiently for all of the pigs to engage the pipe when in the fourth position.

During deployment, the outlet pipe 7 may be left open for subsequent connection to other apparatus, such as a control valve or shut-off valve or a riser for carrying oil from the pipe 1 to a storage facility, for example located in the vessel 5. In order to facilitate the deployment, no attem pt may be made to control the spillage of oil d uri ng deployment of the apparatus 3. However, once the apparatus 3 has been successfully deployed within the pipe 1 , remedial action may be taken to prevent or reduce further spillage. For example, valves may be fixed to the outlet pipe 7, if they are not already in place, and may be operated so as to close the outlet pipe 7. Alternatively or additionally, a riser may be attached to the outlet pipe 7 so as to conduct oil to the vessel 5 or to another vessel with storage facilities. Once the spillage has been brought under control, a more permanent arrangement may be provided for preventing further spillage.

In an alternative embodiment, the apparatus 3 may be dimensioned so that it fits over the end of the pipe 1 , which is therefore inserted inside the apparatus. In this case, the seals 14 and friction pigs 16 are disposed radially inside the chamber 9 so as to engage an outer wall of the pipe 1 .

Figure 3 shows an apparatus 3 which is also for insertion inside the end of the broken pipe 1 . The apparatus comprises an outlet pipe 7 surrounded by a thin wall metal tube 20, which is typically in the form of a resilient membrane made of stainless steel. The tube 20 is sealed to the outlet tube 7 at its ends by means of seals 10 and 1 1 . The tube 20 is spaced from the outlet tube in its first position by means of annular supports such as 21 which also reinforce the outlet pipe 7 against crushing. The pipe 7, the tube 20 and the seals 1 0 and 1 1 define a chamber 9 whose volume is reduced by the presence of the rings 21 such that the chamber 9 may be filled more quickly for a faster reaction time. The rings 21 have through-bores such as 22 so as to provide free hydraulic or pneumatic communication along the length of the chamber 9. The chamber 9 is provided with a connection 23 for connecting to an hydraulic or pneumatic pressure source, for example in a vessel as shown in Figure 1 . The connection is connected to a non-return valve 24, which permits a flow of fluid into the chamber 9 so as to increase the hydraulic or pneumatic pressure therein but prevents a return flow so as to maintain the increased pressure.

The apparatus 3 shown in Figure 3 is deployed in the same way as the apparatus shown in Figure 2. During deployment, the pressure in the chamber 9 is sufficiently low such that the flexible membrane of thin wall stainless steel forming the tube 20 rests against the rings 21 . Once the apparatus has been deployed inside the tube 1 , the hydraulic or pneumatic pressure in the chamber 9 is increased so that the membrane forming the tube 20 expands to provide a frictional and sealing engagement with the inner wall of the pipe 1 . A pressure up to around 300 bar has been found to be suitable, but this will depend on the thickness of the thin wall. The length of the apparatus combined with the expansion of the membrane 20 and the pressure within the chamber 9 are such as to provide sufficient friction to resist the pressure within the pipe 1. The apparatus is therefore held in place and provides a seal between the outlet pipe 7 and the broken oil pipe 1 . The flow of oil through the outlet pipe 7 may then be controlled as described hereinbefore. The thin wall metal tube 20 can be coated or textured in order to provide additional grip to the surface of the outlet oil pipe 7, which ensures that the apparatus is firmly secured to the outlet oil pipe when the tube is in frictional and sealing engagement with the inner wall of the pipe 1 . Examples of coatings include thermal coatings such as metals or ceramics. Tungsten carbide is particularly suitable. The coating is applied using any conventional application means, for example spraying or plasma spraying. Another example of a coating is a dispersion of a hard particulate material such as tungsten carbide in a carrier material such as an epoxy resin. Various types of coating are suitable, provided that they have the effect of increasing the friction between the thin wall metal tube 20 and a surface of the outlet oil pipe 7.

Figure 3 also shows two external reaction/support rings 25 which are (optionally) provided on the outside of the membrane 20 adjacent the connection 23. The rings 25 are provided if "full deployment" may not be possible. The rings 25 are in the form of loose collars (which may be replaced by a single wider collar) disposed over the tube 20 and, for example, extending up to half of the length of the tube 20. If "full deployment" is possible such that the apparatus 3 is fully inserted into the pipe 1 , the rings 25 are pushed off the end of the tube 20 adjacent the seal 1 1 and the whole of the tube 20 contacts the pipe 1 when the chamber is pressurised. Conversely, if full deployment is not possible such that only part of the tube 20 is inserted in the pipe 1 , the chamber 9 may still be pressurised without risk of bursting the steel membrane forming the part of the tube 20 outside the pipe 1 . In particular, expansion of this part of the tube 20 is constrained by the rings 25 (or the remaining rings 25) and limits expansion such that the tube 20 does not burst. The apparatus may therefore still be effective in reducing spillage from the pipe.

The apparatus 3 shown in Figure 4 differs from that shown in Figure 3 in that the rings 21 and the membrane 20 are disposed inside the outlet pipe 7. Thus, in order to engage the apparatus 3 with the pipe 1 , the pressure supplied to the chamber 9 inflates the chamber and the membrane 20 is pressed against the outer surface of the pipe 1 to provide a frictional and sealing engagement. The above description refers to two embodiments in which a single set of seals are used. However, it is more effective to use multiple sets of seals, as shown in Figure 5. The apparatus 3 shown in Figure 5 has a first set of seals 25 and a second set of seals 26. The first set of seals 25 is connected via a first connector to a source of pressurisable fluid by a first hydraulic or pneumatic pipeline 27, and the second set of seals is connected via a second connector to a source of pressurisable fluid by a second hydraulic or pneumatic pipeline 28. In this example, the first set of seals has an associated first chamber for pressurisable fluid and the second set of seals has an associated second chamber for a pressurisable fluid.

An advantage of providing one or more additional sets of seals and additional hydraulic or pneumatic pipes or lines is that redundancy is built into the apparatus. Deployment of the apparatus 3 can be very difficult, especially where the broken oil pipe 1 is at a great depth underwater or the fluid flow from the broken oil pipe 1 is at a high pressure. It is possible that during deployment, one of the hydraulic or pneumatic pipes or lines may become broken or damaged. The additional hydraulic or pneumatic pipe or line provides a backup in this event, allowing deployment of the device to continue. A further advantage of providing an additional hydraulic or pneumatic pipe or line is that, in the event that the apparatus is successfully deployed with no damage to any of the hydraulic or pneumatic pipes or lines, a stronger seal can be effected with the broken oil pipe 1 , allowing the apparatus to be deployed under higher crude oil pressure than if the apparatus only had one set of inflatable seals and friction pigs.

Note that any combination of types of seal may be used. For example, the first set of seals 25 and the second set of seals 26 may include any combination of the seals 12 shown in Figure 2 and the thin wall metal tube 20 shown in Figure 3. The type of seal may be selected depending on the type of fluid being conveyed by the broken oil pipe 1 . If the fluid is, for example, low pressure gas, then an inflatable rubber seal might be more appropriate as the seal formed is likely to be more gas-tight than a seal formed using a steel tubular wall.

Although various embodiments have been shown and described in detail, the claims are not limited to any particular embodiment or example. None of the above description should be read as implying that any particular element, step, or function is essential such that it must be included in the claims' scope. The scope of protection is defined by the claims.

Claims

CLAIMS:

1 . An apparatus for sealing to a broken pipe conveying a first fluid under pressure, said apparatus comprising:

a first chamber for a pressurisable second fluid;

a second chamber for a pressurisable third fluid;

a first seal which is moveable from a first position, in which said first seal is free of said broken pipe during engagement of said apparatus with said broken pipe, to a second position in which, following said engagement, said first seal is in frictional and sealing contact with said broken pipe in response to an increased second fluid pressure in said first chamber;

a first connector for connecting said chamber to a source of pressurised said second fluid;

a second seal which is moveable from a first position, in which said second seal is free of said broken pipe during engagement of said apparatus with said broken pipe, to a second position in which, following said engagement, said second seal is in frictional and sealing contact with said broken pipe in response to an increased third fluid pressure in said second chamber; and

a second connector for connecting said chamber to a source of pressurised third fluid.

2. An apparatus as claimed in claim 1 , in which said apparatus is insertable into an end of said broken pipe when said seals are in said first position.

3. An apparatus as claimed in claim 1 , in which an end of said broken pipe is insertable into said apparatus when said seals are in said first position.

4. An apparatus as claimed in any of claims 1 to 3, further comprising a rigid body and in which said seals and said chambers are disposed between said broken pipe and said rigid body following said engagement.

5. An apparatus as claimed in claim 4, in which said rigid body comprises an outlet pipe for said first fluid from said broken pipe.

6. An apparatus as claimed in claim 5, in which said outlet pipe is connected to one of a control valve, a shut-off valve, and a riser.

7. An apparatus as claimed in any of claims 1 to 6, in which each at least one seal comprises an annular seal.

8. An apparatus as claimed in any of claims 1 to 7, in which at least one seal is biased towards said first position.

9. An apparatus as claimed in claims 1 to 8, in which at least one seal comprises a torodial rubber seal defining an inner volume in fluid communication with a chamber.

10. An apparatus as claimed in any of claims 1 to 8, in which at least one seal comprises a resilient membrane.

1 1 . An apparatus as claimed in claim 1 0, in which said membrane is made of stainless steel.

12. An apparatus as claimed in claim 10 or 1 1 , in which said membrane comprises a coating, said coating being provided to increase friction between the membrane and the broken pipe when the membrane is engaged with the broken pipe.

13. An apparatus as claimed in claim 1 0, 1 1 or 12, in which said membrane comprises a textured surface, said textured surface being provided to increase friction between the membrane and the broken pipe when the membrane is engaged with the broken pipe.

14. An apparatus as claimed in any of claims 1 to 13, further comprising at least one friction pig which is movable from a third position, in which said friction pig is free of said broken pipe during said engagement, to a fourth position, in which said friction pig is in frictional engagement with said broken pipe following said engagement.

15. An apparatus as claimed in claim 14, wherein a surface of said friction pig arranged to be in engagement with said broken pipe following said engagement is selected from any of a coated surface and a textured surface,.

16. An apparatus as claimed in claim 14 or 1 5, in which each said at least one friction pig comprises a piston disposed in a cylinder in fluid communication with said chamber.

17. An apparatus as claimed in any of claims 1 to 16, in which any of said first and second connectors is connected to a non-return valve for non-return of said second or third fluid to said source.

18. An apparatus as claimed in any of claims 1 to 17, in which any of said second and third fluid is one of hydraulic and pneumatic fluid.

19. An apparatus as claimed in any of claims 1 to 18, in which said broken pipe is for conveying production fluid from a well.

20. An apparatus as claimed in claim 19, in which said production fluid is a hydrocarbon.

21 . A method of sealing an apparatus as claimed in any of claims 1 to 20 to a broken pipe, said method comprising the steps of: deploying said apparatus with said seals in said first position; engaging said apparatus with said broken pipe; and increasing said second fluid and third fluid pressures in said first and second chambers such that said at least one seal is in frictional and sealing contact with said broken pipe.

22. A method as claimed in claim 21 , in which said broken pipe is an underwater pipe and said engaging step comprising manoeuvring said apparatus with a remotely operated vehicle.

23. A method as claimed in claim 21 or 22, comprising the subsequent step of reducing an outflow of said first fluid.