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WO2002063127A1 - Manchon de flottabilite non structural - Google Patents

Manchon de flottabilite non structural Download PDF

Info

Publication number
WO2002063127A1
WO2002063127A1 PCT/US2002/003135 US0203135W WO02063127A1 WO 2002063127 A1 WO2002063127 A1 WO 2002063127A1 US 0203135 W US0203135 W US 0203135W WO 02063127 A1 WO02063127 A1 WO 02063127A1
Authority
WO
WIPO (PCT)
Prior art keywords
buoyancy
frame
connectors
riser
buoyancy apparatus
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US2002/003135
Other languages
English (en)
Inventor
Brad R. Campbell
Paul Berner
Mehrdad Mortazavi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ExxonMobil Upstream Research Co
Original Assignee
ExxonMobil Upstream Research Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ExxonMobil Upstream Research Co filed Critical ExxonMobil Upstream Research Co
Priority to GB0320568A priority Critical patent/GB2390109B/en
Publication of WO2002063127A1 publication Critical patent/WO2002063127A1/fr
Priority to NO20033467A priority patent/NO20033467L/no
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B21/00—Tying-up; Shifting, towing, or pushing equipment; Anchoring
    • B63B21/50—Anchoring arrangements or methods for special vessels, e.g. for floating drilling platforms or dredgers
    • B63B21/502—Anchoring arrangements or methods for special vessels, e.g. for floating drilling platforms or dredgers by means of tension legs
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
    • E21B17/01—Risers
    • E21B17/012—Risers with buoyancy elements

Definitions

  • the invention relates to device used to provide tension for a riser in an offshore drilling and/or production apparatus.
  • a typical system used to obtain and produce hydrocarbons from offshore reservoirs comprises a host floating vessel located on the surface of the ocean, hydrocarbon producing wells located on the ocean floor and a conduit used for drilling or hydrocarbon recovery that connects the wells to the host floating vessel. This conduit is commonly referred to as a riser.
  • buoyancy chambers In operation, risers in these offshore systems need to be maintained in tension to avoid buckling or other failures.
  • a common method used by the petroleum industry for maintaining this tension is by attaching buoyancy chambers near the tops of the risers.
  • a problem encountered by the industry has been the high costs associated with manufacturing a suitable housing for the buoyancy chambers that can withstand the various loads acting upon it in the offshore environment. For example, movement of the host floating platform and wave/current forces cause the riser and buoyancy chamber housings to bend.
  • contact between the buoyancy chamber housings and the lateral support points causes localized bending in the housings. Accordingly, a significant amount of structural steel must be added to the buoyancy chamber housing to resist these loads.
  • a buoyancy apparatus for providing tension to an offshore riser that comprises at least one buoyancy element and a frame that comprises a plurality of vertical members externally disposed to the buoyancy element, and a plurality of connectors securing the vertical members to the riser.
  • FIG 1. is an elevational view of a floating platform in accordance with a conventional riser / buoyancy system.
  • FIG 2. is a perspective view of a conventional buoyancy can.
  • FIG 3. is a perspective view of an embodiment of a buoyancy element that may be used in accordance with the present invention.
  • FIG 4. is a perspective view of an embodiment of the buoyancy system in accordance with the present invention.
  • FIGS 5a and 5b. are perspective views of embodiments of the buoyancy system in accordance with the present invention, wherein the frame had additional internal connectors.
  • FIG. 6. is a perspective view of an embodiment of the buoyancy system in accordance with the present invention, with a frame containing arched bracing members.
  • FIG 7. is a perspective view of an embodiment of the buoyancy system in accordance with the present invention, shown in relation to contact with a riser guide.
  • FIG. 1 A typical offshore riser system is shown in Fig. 1.
  • Riser 15 passes through a moonpool within the floating host facility (only the lower portion of the host facility indicated), and connects to the subsea reservoir.
  • the riser 15 is maintained in tension by a series of buoyancy elements, shown in Fig. 1 as buoyancy cans 100, which are connected to a stem pipe 25.
  • a stem pipe is a cylindrical pipe that concentrically surrounds a riser and is attached to the riser near the riser's top, thereby transferring buoyancy from the buoyancy cans to the riser.
  • Riser guides 70 provide lateral support for the riser/buoyancy system by allowing free vertical motion of the riser/buoyancy can configuration within the host facility, while restricting its lateral movements.
  • the buoyancy cans 100 can be directly subjected to loads caused by movement of the host facility and wave and current action. Moreover, high bending stresses can occur at the connections between individual buoyancy cans due to stiffness discontinuity at these locations. Accordingly, these cans 100 are typically constructed with an additional amount of structural steel 20, as indicated in Fig. 2, to provide it with the necessary strength and durability to withstand the loads.
  • the current invention is a riser-tensioning device that comprises a buoyancy element and a frame enclosing the buoyancy element.
  • the frame is secured directly to the riser, or indirectly to the riser through a riser stem pipe, and allows buoyancy to be transferred by the buoyancy element through the frame and to the riser.
  • the frame can be constructed so that it is neutrally or positively buoyant in water, and therefore the weight of the frame does not counteract the buoyancy provided by the buoyancy element.
  • the frame accepts external loads that would otherwise act upon the buoyancy element.
  • the buoyancy element can therefore be made with fewer structural requirements, and can be made of lighter materials, which may lead to reduced size and reduced manufacturing and materials costs.
  • the buoyancy element may comprise any suitable buoyancy device or devices used in the offshore petroleum industry to provide buoyancy to a riser, including but not limited to buoyancy chambers (i.e. buoyancy cans) and syntactic foams.
  • the buoyancy element ih this embodiment is a buoyancy can which comprises a housing 65 with an outer shell 150 and an inner shell 155 concentrically positioned within, thereby forming an annulus between the outer and inner shells.
  • Inner shell 155 may be comprised of stem pipe 25, as is indicated in Fig. 3.
  • stem pipe 25 is not required, as will be explained later, and inner shell 155 may comprise riser 15 if no stem pipe is used.
  • Flange 82 may be present on the ends of stem pipe 25 to provide connection points for adjacent stem pipes 25, which may be desirable when using multiple buoyancy elements as will be explained later.
  • the annulus is closed at the top 185 to form buoyancy chamber 165.
  • the annulus may be open or closed at the bottom 175 of the buoyancy chamber 165.
  • the buoyancy chamber 165 is filled or depleted of air or other gases using air service lines 90 to provide the desired buoyancy.
  • the buoyancy chamber housing 65 may contain internal or external steel bracing 20, such as shown in Fig. 2, to provide additional structural support, but may also be constructed without such additional structural elements, as indicated in Fig. 3. Although this embodiment describes the buoyancy chamber housing 65 as being cylindrical in shape, the housing 65 is not limited in this manner.
  • the external frame 60 is designed and constructed to carry the loads exerted by external forces that would otherwise act on the buoyancy chamber housing 65.
  • the external frame 60 may be designed with various configurations while still accomplishing this load transfer.
  • the present embodiment shows a frame 60 comprised of frame columns 75 disposed vertically along the exterior of the housing 65 and connectors 80, here radial arms located above and below the housing 65, that connect frame columns 75 to the riser stem pipe 25.
  • the embodiment disclosed in Fig. 4 shows four vertical frame columns 75, the invention is not intended to be limited as such.
  • Other connectors including but not limited to plates or disks may used instead of or in addition to radial arms to secure the frame columns 75 to the riser stem pipe 25.
  • FIG. 5a Another embodiment of the invention is disclosed in Fig. 5a, where a plurality of connectors 80A - 80E are positioned along the length of the external frame 60.
  • Each connector attaches frame columns 75 to the riser 15, either directly or indirectly, and provides further structural support for the frame.
  • Indirect attachment includes attachment of the connectors to the riser 15 through a stem pipe 25 (as previously noted), as shown in Fig. 5a.
  • Individual buoyancy elements may be positioned in between the connectors, for example, syntactic foam may be positioned between connectors 80A and 80B, between connectors 80B and 80C, and so forth. Alternatively, the buoyancy element or elements may extend through some or all the connectors. Referring again to Fig.
  • a single buoyancy can 100 extends through three of the plate connectors 80B, 80C and 80D.
  • the three plate connectors 80B - 80D are partially contained within the buoyancy can 100 and contain perforations or other openings 95 that allow air or other fluid to pass therethrough, as fluid communication should be maintained within the buoyancy can 100.
  • the buoyancy can 100 may be constructed in sections, for example sections 65 A - 65D.
  • Section 65A is a tubular element having a closed top and an open bottom, and sections 65B - 65D are tubular elements having open tops and open bottoms. Each section may be secured, by welding or other means, to the connector 80 directly above and below the section. Accordingly, the fluid integrity and the buoyancy of the can 100 is maintained.
  • FIG. 5b Another similar embodiment discloses extending a buoyancy element through a series of vertically aligned perforations 95 in connectors 80.
  • a buoyancy can 100A can be adapted to pass through a series of vertically aligned perforations 95 A in the series of connectors 80.
  • More than one series of vertically aligned perforations for example perforation series 95B, 95C, and 95D, may be present to receive additional buoyancy elements (shown as buoyancy cans 100B - 100D).
  • perforation series 95B, 95C, and 95D may be present to receive additional buoyancy elements (shown as buoyancy cans 100B - 100D).
  • Persons skilled in the art will recognize that modifications, alterations, and variations to this invention are possible without departing from the true intent and scope of the invention.
  • one or more external bracing members 150 connecting the individual frame columns 75 may be provided.
  • These external bracing members 150 may comprise horizontal members, diagonal members, or a combination of horizontal and diagonal members.
  • These bracing members 150 may also be configured to conform to the exterior of the buoyancy element to help improve the load transfer.
  • the bracing members 150 may be radially arched to form a ring about a cylindrically shaped buoyancy chamber housing 65.
  • the frame columns 75 may be constructed of any suitable material that can be selected by one skilled in the art to provide the frame with necessary strength and durability to operate in an offshore environment.
  • the frame columns 75 are constructed of hollow members, and more preferably tubular members, and even more preferably the members are sealed such that they are neutrally or positively buoyant in water.
  • the buoyancy chamber housing 65 of the described embodiment can be constructed of any appropriate material used in the industry for such buoyancy devices, typically steel. But in addition, it can be constructed of lightweight, flexible and inexpensive material including but not limited to rubber, fiberglass and thin steel. The use of such materials can provide cost savings over previously used materials. Moreover, the use of nonmetallic materials eliminates the need for expensive corrosion protection of the housing.
  • the buoyancy elements useful for this invention are not limited to buoyancy cans. Other buoyancy elements used in the offshore industry, including but not limited to syntactic foams, may be used in conjunction with the frame of this invention and would be obvious to one of ordinary skill in the art.
  • Another benefit of the current embodiment is the ability to eliminate unnecessary penetrations in the buoyancy chamber housing for the gas service lines 90. It is undesirable to leave gas service lines 90 unprotected from possible collisions with other objects near the buoyancy can. Accordingly, it is common practice in the industry to introduce gas service lines 90 into the buoyancy chamber 165 through penetrations in the buoyancy chamber housing 65, thereby minimizing exposure to potential collisions. However, in creating these penetrations the buoyancy chamber housing 65 is weakened. As indicated in Fig. 4, the current invention allows the lines 90 to be run along the side of the external frame 60, or within the frame 60 (not shown), thereby protecting the lines 90 from possible collisions. The lines 90 may enter the buoyancy chamber from an open bottom in the housing 175, or an opening (not shown) in a closed housing bottom 175. This design will improve system reliability and enhance the housing's integrity by eliminating the penetrations in the housing.
  • buoyancy elements are typically attached to the riser 15, or riser stem pipe 25, in series with one attached above another, as shown in Fig. 1.
  • Frame 60 may contain top mating elements 84 and bottom mating elements 86 to aid in connecting and maintaining the connection between the attached frames 60.
  • mating element 84 of a lower positioned frame 60 can be connectively received by mating element 86 of a higher positioned frame 60.
  • Other mating elements can be used that would be obvious to one of ordinary skill in the art.
  • Mating elements 84 and 86 when connected, preferably maintain a flush connection respect to the exterior of frame columns 75 so as to not interfere with the vertical movement of the frame/buoyancy element configuration in relation to riser guide 70.
  • Flange 82 may be present on either end of stem pipe 25 to provide a connection point for an adjacent stem pipe 25.
  • Each frame 60 is attached to the riser 15, or riser stem pipe 25, in a manner as previously disclosed. In this way, a continuous external frame 60 is provided over all of the buoyancy elements, thereby eliminating stiffness discontinuity along the buoyancy system and its associated disadvantages, i.e. stresses that lead to bending at connections between buoyancy chamber housings.

Landscapes

  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Mechanical Engineering (AREA)
  • Mining & Mineral Resources (AREA)
  • Fluid Mechanics (AREA)
  • Chemical & Material Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Ocean & Marine Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Earth Drilling (AREA)
  • Other Liquid Machine Or Engine Such As Wave Power Use (AREA)

Abstract

Dispositif tendeur de tube prolongateur destiné à être utilisé dans une installation flottante en mer, qui possède un élément de flottabilité (65) et un châssis (60). Le châssis (60) accepte des charges externes causées par le mouvement de l'installation flottante et l'action des vagues et / ou des courants qui s'exerceraient sinon sur l'élément de flottabilité. Le châssis (60, 75) peut être rendu flottant de matière positive ou neutre, si bien que le poids dudit châssis ne contrecarre pas la flottabilité fournie par l'élément de flottabilité (65).
PCT/US2002/003135 2001-02-05 2002-02-04 Manchon de flottabilite non structural Ceased WO2002063127A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB0320568A GB2390109B (en) 2001-02-05 2002-02-04 Nonstructural buoyancy can
NO20033467A NO20033467L (no) 2001-02-05 2003-08-05 Ikke-strukturell oppdriftstank

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US26658301P 2001-02-05 2001-02-05
US60/266,583 2001-02-05

Publications (1)

Publication Number Publication Date
WO2002063127A1 true WO2002063127A1 (fr) 2002-08-15

Family

ID=23015179

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2002/003135 Ceased WO2002063127A1 (fr) 2001-02-05 2002-02-04 Manchon de flottabilite non structural

Country Status (4)

Country Link
US (1) US20020142683A1 (fr)
GB (1) GB2390109B (fr)
NO (1) NO20033467L (fr)
WO (1) WO2002063127A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2382116A (en) * 2001-09-18 2003-05-21 2H Offshore Engineering Ltd Buoyancy apparatus for tensioning a subsea riser
GB2380747B (en) * 2001-10-10 2005-12-21 Rockwater Ltd A riser and method of installing same
WO2020194064A2 (fr) 2019-03-25 2020-10-01 Acergy France SAS Bouées résistantes à la pression

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7059416B2 (en) * 2003-11-21 2006-06-13 Technip France Buoyancy can for offshore oil and gas riser
NO325540B1 (no) * 2005-02-11 2008-06-16 Nexans Umbilical og fremgangsmate for dens fremstilling
WO2010021907A1 (fr) * 2008-08-21 2010-02-25 Shell Oil Company Installation ou désinstallation d’une structure sous-marine

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3952526A (en) * 1975-02-03 1976-04-27 Regan Offshore International, Inc. Flexible supportive joint for sub-sea riser flotation means
US4099560A (en) * 1974-10-02 1978-07-11 Chevron Research Company Open bottom float tension riser
US4634314A (en) * 1984-06-26 1987-01-06 Vetco Offshore Inc. Composite marine riser system
US4646840A (en) * 1985-05-02 1987-03-03 Cameron Iron Works, Inc. Flotation riser
EP0459649A1 (fr) * 1990-05-30 1991-12-04 Conoco Phillips Company Système de déconnexion d'une colonne montante avec flotteurs gonflables près de la surface
US6371697B2 (en) * 1999-04-30 2002-04-16 Abb Lummus Global, Inc. Floating vessel for deep water drilling and production
US6375391B1 (en) * 1999-03-25 2002-04-23 Pgs Offshore Technology As Guide device for production risers for petroleum production with a “dry tree semisubmersible” at large sea depths

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4740109A (en) * 1985-09-24 1988-04-26 Horton Edward E Multiple tendon compliant tower construction
US5758990A (en) * 1997-02-21 1998-06-02 Deep Oil Technology, Incorporated Riser tensioning device
US6488447B1 (en) * 2000-05-15 2002-12-03 Edo Corporation Composite buoyancy module
US6632112B2 (en) * 2000-11-30 2003-10-14 Edo Corporation, Fiber Science Division Buoyancy module with external frame

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4099560A (en) * 1974-10-02 1978-07-11 Chevron Research Company Open bottom float tension riser
US3952526A (en) * 1975-02-03 1976-04-27 Regan Offshore International, Inc. Flexible supportive joint for sub-sea riser flotation means
US4634314A (en) * 1984-06-26 1987-01-06 Vetco Offshore Inc. Composite marine riser system
US4646840A (en) * 1985-05-02 1987-03-03 Cameron Iron Works, Inc. Flotation riser
EP0459649A1 (fr) * 1990-05-30 1991-12-04 Conoco Phillips Company Système de déconnexion d'une colonne montante avec flotteurs gonflables près de la surface
US6375391B1 (en) * 1999-03-25 2002-04-23 Pgs Offshore Technology As Guide device for production risers for petroleum production with a “dry tree semisubmersible” at large sea depths
US6371697B2 (en) * 1999-04-30 2002-04-16 Abb Lummus Global, Inc. Floating vessel for deep water drilling and production

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2382116A (en) * 2001-09-18 2003-05-21 2H Offshore Engineering Ltd Buoyancy apparatus for tensioning a subsea riser
GB2382116B (en) * 2001-09-18 2004-09-29 2H Offshore Engineering Ltd Buoyancy apparatus
GB2380747B (en) * 2001-10-10 2005-12-21 Rockwater Ltd A riser and method of installing same
WO2020194064A2 (fr) 2019-03-25 2020-10-01 Acergy France SAS Bouées résistantes à la pression
US12195144B2 (en) 2019-03-25 2025-01-14 Acergy France SAS Pressure-resistant buoys
EP4610029A2 (fr) 2019-03-25 2025-09-03 Acergy France SAS Bouées résistant à la pression

Also Published As

Publication number Publication date
NO20033467D0 (no) 2003-08-05
NO20033467L (no) 2003-10-06
GB0320568D0 (en) 2003-10-01
US20020142683A1 (en) 2002-10-03
GB2390109B (en) 2005-01-05
GB2390109A (en) 2003-12-31

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