The field of the invention is various configurations and methods for hybrid towers, and especially for buoyed and stayed tower and riser assemblies.
Numerous marine riser towers are known in the art, and exemplary hybrid towers and configurations are described in, for example, U.S. Pat. Nos. 6,082,391, 6,461,083, 6,837,311, 7,100,694, U.S. Pat. App. No. 2010/0172699, WO 2010/035248 and WO 2010/041229. These and all other extrinsic materials discussed herein are incorporated by reference in their entirety. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
While most of the known hybrid towers can be manufactured and operated without significant challenges in offshore reservoirs at relatively shallow depth, thermal insulation, structural integrity, and weight control for hybrid towers for use at significant depth present substantial challenges. Additionally, as more reservoirs are found that produce corrosive product, solutions are needed to address the significant corrosion issues that occur within the flowlines and risers. Therefore, maintenance, repair and/or expansion of the flowlines and risers in the deepwater field developments has become increasingly important to extend the production life of the fields.
For example, to assist in the delivery of deepwater oil and gas to an offshore floating production and storage vessel (FPSO), flowline risers connect the floating vessel at the sea surface with the pipelines on the sea bed. However, such connection is not trivial, particularly where the offshore field is at a significant depth below sea level. Among other difficulties, most of the currently known structures negatively impact operational flexibility. For example, addition and/or removal, or maintenance of the flowline risers often interrupts continuous product flow. Similarly, where expansion of production capacity is desired, simple addition of new risers to existing structures is generally not possible in a cost-effective manner.
Thus, even though numerous methods and systems are known to convey gas and/or oil from a deep sea location to an offshore floating production and storage vessel or other receiving structure, various problems nevertheless remain. Consequently, there is still a need to provide configurations and methods for towers and risers.
The present invention is directed to hybrid riser tower configurations and methods that not only allow for simplified construction and installation, but also provide flexibility once installed. Moreover, contemplated towers can be coupled to each other via a structural truss or other static element to form operational structures with minimal impact on the marine environment.
In one aspect of the inventive subject matter, a hybrid buoyed and stayed tower and riser assembly comprises a support structure, and a plurality of dividers that are coupled to and radially extend from the support structure. Most typically, a plurality of riser lines is coupled to at least one of the plurality of dividers via a coupling element, and a plurality of isolation valves are fluidly coupled to the plurality of riser lines, respectively, and configured to allow isolation of each individual riser within the tower and riser assembly. In such assemblies, it is further particularly preferred that the coupling element and at least one of the dividers allows addition and/or removal of one or more riser lines by a remotely operated vehicle.
In still further particularly preferred aspects, a riser line includes a riser pipe that is contained in a housing, wherein the riser pipe and/or the housing is isolated by syntactic foam, and wherein the syntactic foam is applied in an amount effective to provide buoyancy to the at least one of the riser line. Alternatively, or additionally, the support structure comprises a structural steel tube, wherein the support structure is at least partially enclosed by syntactic foam. Most typically, the tower and riser assembly comprises a topside element having dynamic flexible jumpers and/or a bottom element having static flexible jumpers.
It is still further contemplated that two or more hybrid buoyed and stayed tower and riser assemblies are coupled to each other, preferably via a structural truss. The truss may be used in various functions, and most preferably to couple one or more steel catenary risers to the structural truss. Alternatively, or additionally, one or more buoyed and stayed towers may be coupled to the assembly, preferably via a riser porch (that may allow for wet storage of flexible risers).
In another aspect of the inventive subject matter, a method of modifying a hybrid buoyed and stayed tower and riser assembly may include a step of providing a support structure and a plurality of dividers that are coupled to and radially extend from the support structure. In another step, a riser line is coupled to or removed from one or more dividers via a coupling element using a remote operable vehicle, a plurality of isolation valves are coupled to or uncoupled from the riser line using the remote operable vehicle to thereby fluidly couple or isolate a topside jumper and a bottom jumper to or from the riser line.
Most preferably, the riser line comprises a riser pipe that is contained in a housing, wherein at least one of the riser pipe and the housing is isolated by syntactic foam, and wherein the syntactic foam is applied in an amount effective to provide buoyancy to the riser line. Furthermore, it is typically preferred that the support structure comprises a structural steel tube, and that the support structure is at least partially enclosed by syntactic foam.
In still further contemplated aspects, the hybrid buoyed and stayed tower and riser assembly is coupled to a second hybrid buoyed and stayed tower and riser assembly or to a buoyed and stayed tower, preferably via a structural truss. Where desired, a steel catenary riser may be coupled to the structural truss. Alternatively, or additionally, the structural truss is configured to allow for wet storage of flexible risers.
Therefore, in a further aspect of the inventive subject matter, a structural truss is configured for coupling a first hybrid buoyed and stayed tower and riser assembly or buoyed and stayed tower to a second hybrid buoyed and stayed tower and riser assembly or buoyed and stayed tower, and is further configured to allow the truss to act as a riser porch, or to receive and maintain a steel catenary riser and/or flexible jumper. Where the first and second towers are coupled to buoyancy elements via respective tethers, it is typically preferred that the truss is coupled to the tethers.
Various objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention.
The inventor has discovered that a hybrid riser tower can be configured such that all or almost all of the disadvantages of heretofore known systems and methods can be overcome in a conceptually simple and effective manner in which multiple riser lines are coupled to a hybrid riser tower via divider, wherein the coupling elements are configured to allow coupling and uncoupling operation using a remote operated vehicle under water.
Additional advantages can be achieved by fluidly coupling isolation valves such that individual riser lines can be fluidly isolated. Among other advantages, such configurations will allow addition, removal, and/or replacement of one or more riser lines that are contained within a single deepwater hybrid riser tower without affecting operations during production. Moreover, contemplated hybrid riser towers may further be coupled with at least one other hybrid riser tower or stayed and buoyed tower, preferably, via a truss to reduce adverse effects of unintended movement and to further provide for expansion capabilities as the truss may be configured as a riser porch and/or to allow for coupling a SCR to the truss.
In one exemplary aspect of the inventive subject matter as schematically illustrated in
In another exemplary aspect of the inventive subject matter as schematically illustrated in
Therefore, it should be recognized that the hybrid riser tower contemplated herein can be locally and substantially completely fabricated to form a free-standing hybrid riser tower that can be transported and installed using conventional offshore anchor handling and tow vessels. Moreover, contemplated configurations and methods presented herein allow multiple small risers from multiple reservoirs to be installed in one fabricated unit and so lower the overall cost per riser by taking advantage of the economies of scale. As a further advantage of the construction of the hybrid riser tower presented herein, it is now also possible to add, remove, and/or replace riser lines that are contained within a single deepwater hybrid riser tower without affecting operations during production. Most typically, such advantage is achieved by a series of isolation valves on the tower and/or at the jumpers that isolate each individual riser line within the single tower. Conventional release clamps and release mechanisms are provided to so allow release of the riser line by remote intervention from an ROV (remote operated vehicle) working underwater. It should still further be appreciated that recovery and replacement of individual riser lines is also now possible by control of the riser line buoyancy using syntactic foam and air to provide positive buoyancy of each riser line. Thus, it should be noted that conventional lower-cost offshore installation vessels such as an anchor handling and tow vessels may be used for recovery and replacement of riser lines.
Exemplary aspects of top and bottom elements of an hybrid riser tower assembly are schematically depicted in
It should still further be appreciated that a single hybrid riser tower or multiple hybrid riser towers allow the motions of the FPSO to be de-coupled from the risers themselves by removing the large weight that would be supported by the FPSO if such towers were not available. In most preferred aspects, flexible dynamic risers connect the free standing riser tower to the FPSO, and the flexible dynamic risers can be removed from the FPSO in an emergency (e.g., storm) and stored on a subsea structural porch that is preferably created by coupling two or more free standing hybrid riser towers together with a structural truss or frame, or by coupling two free standing buoyed and stayed riser towers. As used herein, and unless the context dictates otherwise, the term “coupled to” is intended to include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements). Therefore, the terms “coupled to” and “coupled with” are used synonymously.
Therefore, and viewed from another perspective it should be appreciated that the buoyed and stayed towers and risers presented herein will offer a unique solution with the addition of a cross-braced truss or other structure that couples two riser towers together to form a platform upon which steel catenary risers may be added to expand the offshore field development at a significantly smaller incremental cost than providing a stand alone riser since the platform already exists for expansion. Various exemplary configurations are schematically depicted in
Additionally, steel catenary riser 530 is coupled to the truss 540 in a lazy wave configuration and also provides product to the FPSO.
Where wet storage of the dynamic flexible jumpers is anticipated, configurations as exemplarily depicted in
In still further contemplated aspects of the inventive subject matter as exemplarily shown in
It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the scope of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refers to at least one of something selected from the group consisting of A, B, C . . . and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.
This application claims priority to our U.S. provisional application with the Ser. No. 61/253,765, which was filed Oct. 21, 2009.
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/US2010/053380 | 10/20/2010 | WO | 00 | 8/9/2012 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2011/050064 | 4/28/2011 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
3913668 | Todd et al. | Oct 1975 | A |
4119145 | Tuson | Oct 1978 | A |
4332509 | Reynard et al. | Jun 1982 | A |
4401164 | Baugh | Aug 1983 | A |
4941773 | Vergouw | Jul 1990 | A |
4963420 | Jarrin et al. | Oct 1990 | A |
5330294 | Gueson | Jul 1994 | A |
5639187 | Mungall et al. | Jun 1997 | A |
5855178 | Treu et al. | Jan 1999 | A |
6082391 | Thiebaud et al. | Jul 2000 | A |
6109989 | Kelm et al. | Aug 2000 | A |
6267537 | Breivik et al. | Jul 2001 | B1 |
6461083 | Pionetti et al. | Oct 2002 | B1 |
6595725 | Shotbolt | Jul 2003 | B1 |
6837311 | Sele | Jan 2005 | B1 |
6854930 | Pionetti | Feb 2005 | B2 |
7073593 | Hatton et al. | Jul 2006 | B2 |
7100694 | Legras et al. | Sep 2006 | B2 |
7104330 | Legras et al. | Sep 2006 | B2 |
7434624 | Wilson | Oct 2008 | B2 |
7793726 | Daniel et al. | Sep 2010 | B2 |
8186912 | Saint-Marcoux et al. | May 2012 | B2 |
20040028479 | Horton, III | Feb 2004 | A1 |
20040129425 | Wilson | Jul 2004 | A1 |
20040218981 | Chenin | Nov 2004 | A1 |
20050063788 | Clausen | Mar 2005 | A1 |
20060000615 | Choi | Jan 2006 | A1 |
20080311804 | Bauduin | Dec 2008 | A1 |
20100172699 | Saint-Marcoux | Jul 2010 | A1 |
Number | Date | Country |
---|---|---|
0114687 | Mar 2001 | WO |
02063128 | Aug 2002 | WO |
2008056185 | May 2008 | WO |
2009012196 | Aug 2009 | WO |
2010035248 | Apr 2010 | WO |
2010041229 | Apr 2010 | WO |
Entry |
---|
“International Search Report and the Written Opinion of the International Searching Authority”, Patent Cooperation Treaty, Dec. 22, 2010. |
Number | Date | Country | |
---|---|---|---|
20120292040 A1 | Nov 2012 | US |
Number | Date | Country | |
---|---|---|---|
61253765 | Oct 2009 | US |