Patent Grant
7090006
This application is related to commonly owned U.S. Patent application Ser. No. 10/288,710, entitled “Metal Lined Composite Risers in Offshore Applications” filed on Nov. 5. 2002, which is hereby incorporated by reference herein.
Not applicable.
Not applicable.
The invention relates to a method of re-manufacturing a composite riser section having a damaged original metal liner. More particularly, an expandable replacement liner is installed within the bore of the composite riser section to cover the damaged portion of the original metal liner and is radially expanded to repair the composite riser section. A seal is created between the replacement liner and the composite overwrap to prevent internal fluid from flowing around the replacement liner, through the damaged metal liner and to the outside of the composite riser section.
As exploration and production of oil and gas has moved into deeper water, it has become increasingly important to reduce weight, lower costs, and improve reliability of water-depth sensitive systems such as risers and the like. The term riser generally describes the different types of discrete pipes that extend from the seabed toward the surface of the water. These include components such as drilling risers, production risers, workover risers, catenary risers, production tubing, choke and kill lines and mud return lines. Conventional risers are typically constructed of various metal alloys such as titanium or steel. More recently, however, the oil and gas industry has considered a variety of alternative riser materials and manufacturing techniques including the use of composite materials.
Composite materials offer a unique set of physical properties including high specific strength and stiffness, resistance to corrosion, high thermal insulation, improved dampening of vibrations, and excellent fatigue performance. By utilizing these and other inherent physical characteristics of composite materials, it is believed that composite riser may be used to lower system costs and increase reliability of risers used in deepwater applications. Although there has been a significant effort in the last decade to facilitate and to increase the general use of composites in offshore applications, the acceptance of composite materials by offshore operators continues to be a relatively slow and gradual process. Reasonably good progress has been made to expand the usage of composites for topside components such as vessels, piping and grating. Some advanced components such as high-pressure riser accumulator bottles have already been used successfully in the field. However, in view of the reduced weight, extended life span, lower cost and other enabling capabilities, composite risers are particularly appealing for deep water drilling and production operations.
Composite risers are generally constructed of a number of riser sections each having an outer composite material and an inner liner assembly. Typically, a thin tubular metal or elastomeric liner is coaxially secured to the metal connections at opposite ends to form the liner assembly. For a liner assembly comprising a metal liner, an elastomeric shear ply (usually rubber) is provided along the outer surface of the liner assembly, followed with a composite overwrap reinforcement to form the composite riser section. The composite riser section is then heated to cure the elastomeric shear ply and the composite overwrap. Additionally, an external elastomeric jacket and a layer of composite overwrap may be provided over the composite riser section and thermally cured to reduce external damage by providing impact protection and abrasion resistance to the composite riser section.
The liner assembly is necessary to prevent leakage due to the inherent cracking characteristics of the composite material. Typically, the matrix of the composite overwrap will develop micro cracks at pressures lower than those at which the reinforcing fibers of the composite structure will fail. Matrix micro cracking is due to the thermal stresses induced by the curing cycle and the mechanical stresses induced during the shop acceptance pressure test of the composite riser section during the manufacturing process. Thus, the liner assembly is essential in ensuring fluid tightness of a composite riser to prevent leakage under the condition of matrix micro cracking which is expected.
While elastomeric liners are generally acceptable for production composite risers, they are ill suited for use in composite drilling or workover risers. The likely possibility of damaging, namely cutting or tearing, elastomeric liners with the mechanical tools required for drilling and workover operations makes elastomeric liners less desirable for these types of operations. Accordingly, metal liners for composite drilling and workover risers are being considered. Metal liners also have applications in composite production risers as the metal liners may offer better long term resistance the corrosive production fluids than most elastomeric liners. In a typical composite riser having a metal liner, the metal liner is welded directly to the metal connection assembly at or near the metal-to-composite interface (MCI). Alternatively, the metal liner may be coaxially secured to the MCI through the use of a transition ring. The transition ring is secured at one end to the MCI and is welded at the other end to the metal liner and serves as a transition between the material of the liner and that of the MCI. A transition ring is generally used because the MCI and the connection assembly are generally constructed of a heavier tube stock than the relatively thin metal liner which serves primarily to keep the composite riser from leaking internal fluid. The transition ring is secured to the MCI either by welding or mechanically attaching it to the MCI. A mechanical attachment is preferred over welding when the transition ring and the MCI are formed of different materials.
The invention provides a cost effective alternative to replacing an entire composite riser section when only the liner of the riser section is damaged by disclosing a method of re-manufacturing a composite riser section, particularly in a composite drilling or workover riser. An expandable replacement liner is inserted into the bore of the composite riser section and is positioned to cover the damaged portion of the original liner. The damaged metal liner of the composite riser section may be machined away to form an annular recess between the ends of the liner. The replacement liner is positioned within the annular recess of the damaged metal liner to ensure proper alignment of the replacement liner. The depth of the annular recess can be substantially the same as the thickness of the replacement liner for forming a relatively smooth or flush inner surface in the composite riser section with the replacement liner installed therein.
The replacement liner is held in position as it is radially expanded to an outer diameter which is slightly less than the inner diameter of the composite overwrap and slightly larger than the inner diameter of the elastomeric shear ply. This will allow for an interference fit (i.e. auto-frettage) between the replacement liner and the repaired riser section. Note that if the damaged portion of the liner is not removed to form an annular recess, the replacement liner should be expanded to form an interference fit with the original metal liner itself. Of course, making the repair without removing the damaged portion of the original liner will slightly decrease the inner diameter of the composite riser section.
By way of example only, one end of the replacement liner can be attached to the inside of the composite riser section for holding the replacement liner in place as it is expanded. Alternatively, a plug can be inserted in the bore of the composite riser section proximate one end of the replacement liner to hold it in position as it is being expanded. In addition, one or both ends of the replacement liner can be mechanically flared or expanded at the ends to engage the inner surface of the composite riser section when the replacement liner is positioned over the liner.
Radial expansion of the replacement liner within the composite riser section can be accomplished by the use of an expansion tool having a diameter larger than the inner diameter of the unexpanded liner. The expansion tool is axially moved through the liner to expand the liner to the diameter of the expansion tool which is preferably just slightly larger than the inner diameter of the elastomeric shear ply of the composite riser section. The expansion tool may have rollers set in tension for rolling along the inner surface of the replacement liner as the tool is moved axially through the liner to ensure that the outer surface of the replacement liner conforms to the contours of the inner surface of the composite riser section.
As the outer diameter of the replacement liner is expanded toward the dimension of the inner diameter of the composite overwrap, interface pressure between the outer surface of the replacement liner and the inner surface of the elastomeric shear ply creates a seal therebetween. The seal prevents internal fluid from leaking around the replacement liner, through the damaged portion of the original liner and to the outside of the composite riser. A seal may also be created by applying a sealant, such as an epoxy resin or other suitable adhesive compound, at the ends of the replacement liner between the replacement liner and the damaged metal liner. Alternatively, a sealant can be applied to the inner surface of the elastomeric shear ply or to the outer surface of the replacement liner for creating a seal between the replacement liner and the shear ply as their surfaces come into contact.
The present invention will be better understood in view of the detailed description in conjunction with the following drawings in which like reference numbers refer to like parts in each of the figures, and in which:
A conventional elongated riser [40] extends between the subsea template [30] and the platform [20]. The riser [40] generally comprises a tieback connector [42] proximate to the borehole [34] and a number of riser sections [44] which extend between platform [20] and subsea template [30] and are connected thereto by a taper or flex joint [46] and telescoping section [48] to accommodate the movement of the platform [20] relative to the subsea template [30] and the borehole [34]. The elongated riser sections [44] which comprise conventional riser [40] are coaxially secured together in series. Each riser section [44] must accommodate the pressure of the fluid or gas within the section, the tensile load which is caused by the suspension of additional riser sections [44] below the section, the tensioner load and the bending moments imposed by the wave loads and the relative movement of the platform [20] with respect to the subsea template [30].
In a composite riser, metal connectors are coaxially secured to liners to form a liner assembly which is wrapped with an elastomeric shear ply, a composite overwrap reinforcement, an external elastomeric jacket and an outerwrap for impact and external damage protection. The liners can be metal or elastomeric, depending on the particular application of the composite riser as production, drilling or workover risers.
After curing, an external jacket [500] of an uncured elastomeric material may be applied over the entire length of the resulting composite riser section [100] to prevent migration of seawater into the composite wall and through its interface with the MCI. An outerwrap (not shown) comprising a composite of carbon, glass or other reinforcing fibers in an epoxy resin matrix can be filament wound over the external elastomeric jacket [500] to compact the jacket and to provide scuff protection. The composite riser section is then heated and held at a suitable temperature to cure elastomeric external jacket [500] and the outerwrap.
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The present invention is also suitable for a composite riser section [100 ] having a damaged expandable replacement liner [120], In this embodiment, the damaged expandable liner [120] would be removed by making one or more longitudinal cuts axially along the damaged expandable liner [120], and removing the damaged liner [120] to expose the annular recess [106], for example, as shown in FIG. 7. The removed expandable liner [120] would then be replaced as described herein with another expandable replacement liner [120] to fill the recess [106] and again form the re-manufactured composite riser [100] as shown in FIG. 4. Similarly, the present invention also allows for placing a relatively short length of liner over a damaged portion of the riser section and expanding it. Note that if the whole length is to be covered, access to the ends of the liner will make the process of sealing the liner against the surface of the metal connector easier.
Still referring to
Radial expansion of replacement liner [120] is completed by the use of an expansion tool [130], for example, an expansion mandrel, which is axially moved through replacement liner [120]. Expansion tool [130] should have a diameter larger than the inner diameter of the unexpanded replacement liner [120] and preferably about the same as the desired inner diameter of the remanufactured composite riser section [100]. Expansion tool [130] can be tapered in the direction of movement, its largest diameter being greater than the inner diameter of the unexpanded replacement liner [120] and about the same as the desired inner diameter of the remanufactured composite riser section [100]. As expansion tool [130] is moved through replacement liner [120], the tool [130] axially expands liner [120] to an inner diameter which is about the same as the largest outer diameter of the tool [130]. The replacement liner [120] expansion can also be accomplished with hydraulic pressure applied to a moving pig. However, this method is generally more suitable for an installation in which the replacement liner extends along the whole length of the riser section.
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While a number of preferred embodiments of the invention have been shown and described herein, modifications may be made by one skilled in the art without departing from the spirit and the teachings of the invention. The embodiments described herein are exemplary only, and are not intended to be limiting. Many variations, combinations, and modifications of the invention disclosed herein are possible and are within the scope of the invention. Accordingly, the scope of protection is not limited by the description set out above, but is defined by the claims which follow, that scope including all equivalents of the subject matter of the claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 2139745 | Goodall | Dec 1938 | A |
| 2661225 | Lyon et al. | Dec 1953 | A |
| 2812025 | Teague et al. | Nov 1957 | A |
| 3477506 | Malone | Nov 1969 | A |
| 3489220 | Kinley | Jan 1970 | A |
| 3529853 | Triest et al. | Sep 1970 | A |
| 3768842 | Ahlstone | Oct 1973 | A |
| 4290836 | McPherson et al. | Sep 1981 | A |
| 4449281 | Yoshida et al. | May 1984 | A |
| 4501327 | Retz | Feb 1985 | A |
| 4589801 | Salama | May 1986 | A |
| 4634314 | Pierce | Jan 1987 | A |
| 4728224 | Salama et al. | Mar 1988 | A |
| 4745977 | Love et al. | May 1988 | A |
| 4875717 | Policelli | Oct 1989 | A |
| 5097585 | Klemm | Mar 1992 | A |
| 5105854 | Cole et al. | Apr 1992 | A |
| 5185215 | Adams et al. | Feb 1993 | A |
| 5233737 | Policelli | Aug 1993 | A |
| 5348095 | Worrall et al. | Sep 1994 | A |
| 5398975 | Simmons | Mar 1995 | A |
| 5474132 | Gallagher | Dec 1995 | A |
| 5483894 | Facciano et al. | Jan 1996 | A |
| 5487411 | Goncalves | Jan 1996 | A |
| 5725026 | Maimets | Mar 1998 | A |
| 5785120 | Smalley et al. | Jul 1998 | A |
| 5813467 | Anderson et al. | Sep 1998 | A |
| 5944124 | Pomerleau et al. | Aug 1999 | A |
| 5988300 | Pomerleau et al. | Nov 1999 | A |
| 6042152 | Baldwin et al. | Mar 2000 | A |
| 6050612 | Wolterman | Apr 2000 | A |
| 6250385 | Montaron | Jun 2001 | B1 |
| 6405762 | Bunch | Jun 2002 | B1 |
| 6457532 | Simpson | Oct 2002 | B1 |
| 6561227 | Cook et al. | May 2003 | B1 |
| 20010045289 | Cook et al. | Nov 2001 | A1 |
| 20030047939 | Whitehead et al. | Mar 2003 | A1 |
| Number | Date | Country |
|---|---|---|
| 2320028 | Mar 2001 | CA |
| 0 907 049 | Apr 1999 | EP |
| Number | Date | Country | |
|---|---|---|---|
| 20040084188 A1 | May 2004 | US |
