WO2003070561A1 - Arrangement at a riser tower - Google Patents

Arrangement at a riser tower Download PDF

Info

Publication number
WO2003070561A1
WO2003070561A1 PCT/NO2003/000046 NO0300046W WO03070561A1 WO 2003070561 A1 WO2003070561 A1 WO 2003070561A1 NO 0300046 W NO0300046 W NO 0300046W WO 03070561 A1 WO03070561 A1 WO 03070561A1
Authority
WO
WIPO (PCT)
Prior art keywords
tower
seabed
buoy
riser
anchor
Prior art date
Application number
PCT/NO2003/000046
Other languages
French (fr)
Inventor
Terje Magnussen
Original Assignee
Terje Magnussen
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 Terje Magnussen filed Critical Terje Magnussen
Priority to AU2003206450A priority Critical patent/AU2003206450A1/en
Publication of WO2003070561A1 publication Critical patent/WO2003070561A1/en

Links

Classifications

    • 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

Definitions

  • This invention regards a method of installing a subsea buoy, in particular a subsea buoy designed to form a subsea riser tower.
  • the invention also deals with a device for carrying out the method.
  • a submerged riser tower usually comprises a submerged buoy connected to the seabed by so-called tension legs, principally of the same type as those used for floating, so-called tension leg platforms.
  • the riser tower is further connected to production pipes located on the seabed, by means of relatively rigid risers running from the seabed to the riser tower.
  • the riser tower is connected to a vessel by means of a flexible riser.
  • the object of the invention is to remedy the disadvantages of prior art.
  • the anchoring operation can be carried out by a conventional drilling vessel.
  • a drilling vessel is constructed to be able to join and lower liners into the seabed, and may thus advantageously be used to cost- effectively anchor a riser tower of the type in question. If so desired, wells may also be drilled through said riser.
  • the same drilling vessel may be used to join, lower and suspend risers through openings in the riser tower, whereupon the lower portions of the risers are connected to production pipes located on the seabed.
  • the invention also regards a method of supporting the risers in the sea between the seabed and the riser tower, with guide frames being disposed on the seabed prior to the anchor pipes being positioned.
  • Figure 1 shows a ready installed riser tower during petroleum production
  • Figure 2 shows a deployed foundation frame that carries with it a number of guide frames, where the first anchor pipe is being lowered;
  • Figure .3 is a partially sectional side view of the foundation frame of figure 2;
  • Figure 4 is a plan view of the foundation frame in figure 3;
  • Figure 5 is a scaled-up drawing of an anchor pipe penetration sleeve in the foundation frame
  • Figure 6 shows the foundation frame at the point of lowering a third anchor pipe
  • Figure 7 shows the foundation frame fully anchored and a tower buoy positioned over the foundation frame, with temporary anchoring being installed between the foundation frame and the tower buoy;
  • Figure 8 shows the upper portion of the first anchor pipe being lowered through the tower buoy to the lower portion of the first anchor pipe
  • Figure 9 shows the upper portion of the last anchor pipe . being lowered through the tower buoy to the lower portion of the last anchor pipe;
  • Figure 10 shows the tower buoy fully anchored to the seabed, and where the guide frames have been arranged at suitable intervals along the upper portion of the anchor pipes;
  • Figure 11 is a scaled-up drawing of the means of securing the guide frames to the anchor pipes;
  • Figure 12 shows the riser tower during the lowering of the first riser
  • Figure 13 shows the riser tower after the risers have been set (lowered) and the first flexible pipe connection is in the process of being pulled in and connected to a riser;
  • Figure 14 shows the riser tower fully connected to pipes on the seabed, and where the tower buoy is equipped with a wellhead valve, with the drilling vessel carrying out drilling operations through one of the anchor pipes.
  • reference number 1 denotes a submerged riser tower in the form of a tower buoy 2 connected to the seabed 4 by means of three joinable anchor pipes 6.
  • the anchor pipes 6 are connected to the tower buoy 2 and project down to a foundation frame 8 and further down into the seabed 4.
  • guide frames 12 have been arranged at suitable intervals.
  • the guide frames 12 are fitted with through guides 14 for a plurality of risers 16.
  • the risers 16 are connected to the tower buoy 2, projecting down into the sea to a level immediately above the seabed 4, where they are connected to pipelines 18 on the seabed 4 by means of flexible hose connections 20.
  • the riser tower 1 is connected to a production vessel 22 on the surface of the sea 24 by means of a flexible connection 26, where the connection 26 comprises the necessary pipes and cables for transporting well fluid and chemicals, and also for communication between the production vessel 22 and the riser tower 1.
  • the foundation frame 8 When a riser tower 1 according to the invention is to be installed at the production site, the foundation frame 8 is first lowered onto the seabed 4, see figure 2.
  • the foundation frame is equipped with a number of guide frames 12.
  • a drilling vessel 28 is positioned on the surface of the sea 24 and lowers one of the anchor pipes 6 through a through-going guide 30 in the foundation frame 8.
  • the main guides 31 of the guide frames 12 coincide with and enclose the guide 30.
  • the anchor pipes 6 may be liners or other preferably joinable pipes or stays.
  • the guide 30 Internally, the guide 30 is provided with an annular shoulder 32, see figure 5.
  • a landing ring 34 is joined to the anchor pipe 6 at a predetermined distance from the lower end of the anchor pipe 6. When the anchor pipe 6 is displaced a distance into the seabed 4, the landing ring 34 stops against the shoulder 32, thereby fixing the foundation frame 8 to the seabed 4.
  • the composition and geological properties of the seabed 4 must be determined in order to decide how far into the seabed 4 the anchor pipes 6 must be inserted.
  • the anchor pipes 6 may be fixed to the seabed by frictional force or be concreted to 'the seabed 4 in accordance with known techniques.
  • the upper portion 10 of the anchor pipe 6 is unscrewed from the lower portion of the anchor pipe 6 immediately above the through guide 30 in the foundation frame 8.
  • the remaining anchor pipes 6 are positioned in their respective guides 30 in a similar manner, see figure 6.
  • the tower buoy 2 is then submerged and positioned at a predetermined depth in the sea, e.g. by means of an anchor handling vessel 36 tied in to the tower buoy 2 by a wire 38, see figure 7.
  • the ballast of the tower buoy may be adjusted via a control connection 40 running between the tower buoy 2 and the drilling vessel 28.
  • Temporary anchoring 42 is interposed between the tower buoy 2 and the foundation frame 8, whereupon the ballast of the tower buoy is adjusted in order to impart the required tension to the temporary anchoring 42 for-the tower buoy 2 to align over the foundation frame 4, see figure 7.
  • An upper anchor pipe portion 10 is then moved down through a through opening 44 in the tower buoy 2 from the drilling vessel 28, see figure 8.
  • the upper portion of the anchor pipe 6 is connected up to the corresponding lower part of the anchor pipe 6 and is suspended in the through opening 44 in the tower buoy 2 in the same manner as that explained -for the foundation frame 8 , see figures 8 and 9.
  • the temporary anchoring 42 is removed, whereupon the tower buoy 2 may be given the required buoyancy for supporting a live load and maintaining a stable position in the sea.
  • the guide frames 12 are then raised to their respective positions along the upper portions 10 of the anchor pipes 6, where they are coupled to the anchor pipes 6 by means of lock frames 46 that abut the shoulder rings 47 on the anchor pipes 6, see figures 10 and 11.
  • a resilient damper 48 is arranged to enclose the anchor pipe.
  • the damper 48 is designed to accommodate horizontal intermovement between the anchor pipes 6, the risers 16 and the guide frames 12.
  • the drilling vessel 28 can be used to lower joined risers 16 through through openings 50 for risers in the tower buoy 2, and further through the openings 14 in the guide frames 12, to a level immediately above the seabed 4, see figure 12.
  • the pipelines 18 located on the seabed 4 may then be connected to their respective risers 16 in a manner that is known per se, by means of the flexible hose connections 20.
  • One or more of the anchor pipes 6 may be equipped with a wellhead valve 54 at the tower buoy 2, whereby the anchor pipes 6 may serve as pipes for well drilling according to techniques that are known per se.
  • the number of anchor pipes 6 and risers 16 must be adjusted according to the operating conditions on site.
  • the necessary subsea connecting operations may be performed by methods that are known per se, such as the use of an unmanned subsea vessel (ROV - remote operated vehicle).
  • ROV - remote operated vehicle an unmanned subsea vessel

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Earth Drilling (AREA)

Abstract

A method and arrangement for anchoring a subsea riser tower (1) comprising a submerged tower buoy (2) and at least one riser (16), and where anchor pipes (6) are displaced down into the seabed (4), preferably by means of a drilling vessel (28), and where the tower buoy (2) is placed below the surface of the sea (24) in a position over the set anchor pipes (6), whereupon the anchor pipes (6) are connected to the tower buoy (2).

Description

ARRANGEMENT AT A RISER TOWER
This invention regards a method of installing a subsea buoy, in particular a subsea buoy designed to form a subsea riser tower. The invention also deals with a device for carrying out the method.
When producing petroleum in deep water, it has proven to be advantageous to place a submerged riser tower at a distance below the surface of sea which is significantly smaller than the depth of the ocean at the production site. The main advantage of using such a tower is that it allows equipment and methods for petroleum production in shallow waters to be used also at these depths.
According to prior art, a submerged riser tower usually comprises a submerged buoy connected to the seabed by so- called tension legs, principally of the same type as those used for floating, so-called tension leg platforms. The riser tower is further connected to production pipes located on the seabed, by means of relatively rigid risers running from the seabed to the riser tower. During petroleum production, the riser tower is connected to a vessel by means of a flexible riser.
Prior to installation, a riser tower according to prior art' with horizontally mounted risers is towed from the construction site to the installation site. It is well known that this transport and the subsequent turnabout of the riser from the horizontal to the vertical position puts a lot of strain on the structures. Anchoring by means of tension leg devices has proven to be relatively complex and expensive.
The object of the invention is to remedy the disadvantages of prior art.
The object is achieved in accordance with the invention by the characteristics stated in the description below and in the appended claims.
By designing the submerged riser in a manner such that it may be anchored to the seabed by mainly conventional liners, the anchoring operation can be carried out by a conventional drilling vessel. As is well-known, a drilling vessel is constructed to be able to join and lower liners into the seabed, and may thus advantageously be used to cost- effectively anchor a riser tower of the type in question. If so desired, wells may also be drilled through said riser.
After the riser tower has been, anchored, the same drilling vessel may be used to join, lower and suspend risers through openings in the riser tower, whereupon the lower portions of the risers are connected to production pipes located on the seabed.
The invention also regards a method of supporting the risers in the sea between the seabed and the riser tower, with guide frames being disposed on the seabed prior to the anchor pipes being positioned.
The following describes a non-limiting example of a preferred method illustrated in the accompanying schematic drawings, in which:
Figure 1 shows a ready installed riser tower during petroleum production;
Figure 2 shows a deployed foundation frame that carries with it a number of guide frames, where the first anchor pipe is being lowered;
Figure .3 is a partially sectional side view of the foundation frame of figure 2;
Figure 4 is a plan view of the foundation frame in figure 3;
Figure 5 is a scaled-up drawing of an anchor pipe penetration sleeve in the foundation frame;
Figure 6 shows the foundation frame at the point of lowering a third anchor pipe; Figure 7 shows the foundation frame fully anchored and a tower buoy positioned over the foundation frame, with temporary anchoring being installed between the foundation frame and the tower buoy;
Figure 8 shows the upper portion of the first anchor pipe being lowered through the tower buoy to the lower portion of the first anchor pipe;
Figure 9 shows the upper portion of the last anchor pipe . being lowered through the tower buoy to the lower portion of the last anchor pipe;
Figure 10 shows the tower buoy fully anchored to the seabed, and where the guide frames have been arranged at suitable intervals along the upper portion of the anchor pipes;
Figure 11 is a scaled-up drawing of the means of securing the guide frames to the anchor pipes;
Figure 12 shows the riser tower during the lowering of the first riser;
Figure 13 shows the riser tower after the risers have been set (lowered) and the first flexible pipe connection is in the process of being pulled in and connected to a riser; and
Figure 14 shows the riser tower fully connected to pipes on the seabed, and where the tower buoy is equipped with a wellhead valve, with the drilling vessel carrying out drilling operations through one of the anchor pipes. In the drawings, reference number 1 denotes a submerged riser tower in the form of a tower buoy 2 connected to the seabed 4 by means of three joinable anchor pipes 6. The anchor pipes 6 are connected to the tower buoy 2 and project down to a foundation frame 8 and further down into the seabed 4.
Along the upper portion 10 of the anchor pipes 6 between the tower buoy 2 and the seabed 4, guide frames 12 have been arranged at suitable intervals. The guide frames 12 are fitted with through guides 14 for a plurality of risers 16. The risers 16 are connected to the tower buoy 2, projecting down into the sea to a level immediately above the seabed 4, where they are connected to pipelines 18 on the seabed 4 by means of flexible hose connections 20.
The riser tower 1 is connected to a production vessel 22 on the surface of the sea 24 by means of a flexible connection 26, where the connection 26 comprises the necessary pipes and cables for transporting well fluid and chemicals, and also for communication between the production vessel 22 and the riser tower 1.
When a riser tower 1 according to the invention is to be installed at the production site, the foundation frame 8 is first lowered onto the seabed 4, see figure 2. The foundation frame is equipped with a number of guide frames 12. A drilling vessel 28 is positioned on the surface of the sea 24 and lowers one of the anchor pipes 6 through a through-going guide 30 in the foundation frame 8. The main guides 31 of the guide frames 12 coincide with and enclose the guide 30. The anchor pipes 6 may be liners or other preferably joinable pipes or stays. Internally, the guide 30 is provided with an annular shoulder 32, see figure 5. A landing ring 34 is joined to the anchor pipe 6 at a predetermined distance from the lower end of the anchor pipe 6. When the anchor pipe 6 is displaced a distance into the seabed 4, the landing ring 34 stops against the shoulder 32, thereby fixing the foundation frame 8 to the seabed 4.
The composition and geological properties of the seabed 4 must be determined in order to decide how far into the seabed 4 the anchor pipes 6 must be inserted. The anchor pipes 6 may be fixed to the seabed by frictional force or be concreted to 'the seabed 4 in accordance with known techniques.
After the first anchor pipe 6 has been lowered into and set in the seabed, the upper portion 10 of the anchor pipe 6 is unscrewed from the lower portion of the anchor pipe 6 immediately above the through guide 30 in the foundation frame 8. The remaining anchor pipes 6 are positioned in their respective guides 30 in a similar manner, see figure 6.
The tower buoy 2 is then submerged and positioned at a predetermined depth in the sea, e.g. by means of an anchor handling vessel 36 tied in to the tower buoy 2 by a wire 38, see figure 7. The ballast of the tower buoy may be adjusted via a control connection 40 running between the tower buoy 2 and the drilling vessel 28. Temporary anchoring 42 is interposed between the tower buoy 2 and the foundation frame 8, whereupon the ballast of the tower buoy is adjusted in order to impart the required tension to the temporary anchoring 42 for-the tower buoy 2 to align over the foundation frame 4, see figure 7. An upper anchor pipe portion 10 is then moved down through a through opening 44 in the tower buoy 2 from the drilling vessel 28, see figure 8. The upper portion of the anchor pipe 6 is connected up to the corresponding lower part of the anchor pipe 6 and is suspended in the through opening 44 in the tower buoy 2 in the same manner as that explained -for the foundation frame 8 , see figures 8 and 9.
After all the anchor pipes 6 have been set down, see figure 10, the temporary anchoring 42 is removed, whereupon the tower buoy 2 may be given the required buoyancy for supporting a live load and maintaining a stable position in the sea.
The guide frames 12 are then raised to their respective positions along the upper portions 10 of the anchor pipes 6, where they are coupled to the anchor pipes 6 by means of lock frames 46 that abut the shoulder rings 47 on the anchor pipes 6, see figures 10 and 11.
At each connection between the guide frames 12 and the anchor pipes 6, a resilient damper 48 is arranged to enclose the anchor pipe. The damper 48 is designed to accommodate horizontal intermovement between the anchor pipes 6, the risers 16 and the guide frames 12.
When the guide frames 12 have been positioned, the drilling vessel 28 can be used to lower joined risers 16 through through openings 50 for risers in the tower buoy 2, and further through the openings 14 in the guide frames 12, to a level immediately above the seabed 4, see figure 12. The pipelines 18 located on the seabed 4 may then be connected to their respective risers 16 in a manner that is known per se, by means of the flexible hose connections 20.
One or more of the anchor pipes 6 may be equipped with a wellhead valve 54 at the tower buoy 2, whereby the anchor pipes 6 may serve as pipes for well drilling according to techniques that are known per se.
The number of anchor pipes 6 and risers 16 must be adjusted according to the operating conditions on site. The necessary subsea connecting operations may be performed by methods that are known per se, such as the use of an unmanned subsea vessel (ROV - remote operated vehicle).

Claims

C l a i m s
A method of anchoring a subsea riser tower ( 1 ) comprising a submerged tower buoy (2) and at least one riser (16), c h a r a c t e r i s e d i n that anchor pipes (6) are displaced into the seabed (4), preferably by means of a drilling vessel (28), and that the tower buoy (2) is placed below the surface of the sea (24) in a position above the set anchor pipes (6), whereupon the anchor pipes (6) are connected up to the tower buoy ( 2 ) .
A method in accordance with Claim 1, c h a r a c t e r i s e d i n that a foundation frame (8) is disposed on the seabed (4) prior to the anchor pipes (6) being moved through their respective guides (30) in the foundation frame (8) and into the seabed (4).
A method in accordance with one or more of the preceding claims, c h a r a c t e r i s e d i n that at least one guide frame (12) is connected to the upper portion (10) of the anchor pipes (6) with the desired spacing between the seabed (4) and the tower buoy (2), after the tower buoy (2) has been connected to the anchor pipes (6), the guide frame(s) (12) being located on the foundation frame (8) during the connecting operation.
A method in accordance with one or more of the preceding claims, c h a r a c t e r i s e d i n that at least one riser (16) is displaced into the sea and connected to the tower buoy (2), preferably by means of a drilling vessel (28) .
A method in accordance with one or more of the preceding claims, c h a r a c t e r i s e d i n that the riser(s) (16) is/are moved through respective openings (14) in the guide frame(s) (12).
An arrangement for anchoring a subsea riser tower ( 1 ) comprising a submerged tower buoy (2) and at least one riser (16), c h a r a c t e r i s e d i n that the tower buoy (2) is anchored to the seabed (4) by means of joinable anchor pipes (6) that project down into the seabed ( 4 ) , and where the anchor pipes ( 6 ) are connected to a foundation frame ( 8 ) .
An arrangement in accordance with Claim 6, c h a r a c t e r i s e d i n that a foundation frame (8) is provided with at least one guide frame (12) during deployment on the seabed (4).
PCT/NO2003/000046 2002-02-19 2003-02-07 Arrangement at a riser tower WO2003070561A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2003206450A AU2003206450A1 (en) 2002-02-19 2003-02-07 Arrangement at a riser tower

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NO20020803A NO316635B1 (en) 2002-02-19 2002-02-19 Method and apparatus for riser rods
NO20020803 2002-02-19

Publications (1)

Publication Number Publication Date
WO2003070561A1 true WO2003070561A1 (en) 2003-08-28

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NO2003/000046 WO2003070561A1 (en) 2002-02-19 2003-02-07 Arrangement at a riser tower

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AU (1) AU2003206450A1 (en)
NO (1) NO316635B1 (en)
WO (1) WO2003070561A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011099852A3 (en) * 2010-02-10 2011-12-15 Heerema Marine Contractors Nederland B.V. Method for constructing a riser assembly from a vessel and on a seabed
US20150047852A1 (en) * 2012-03-21 2015-02-19 Francois Regis Pionetti Installation Comprising Seabed-To-Surface Connections Of The Multi-Riser Hybrid Tower Type, Including Positive-Buoyancy Flexible Pipes
US9482059B2 (en) 2012-04-18 2016-11-01 Acergy France SAS Jumper support arrangements for hybrid riser towers

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NO331991B1 (en) * 2005-11-04 2012-05-21 Statoil Asa production and loading system for transporting fluids

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5421676A (en) * 1993-02-08 1995-06-06 Sea Engineering Associates, Inc. Tension leg platform and method of instalation therefor
US5551802A (en) * 1993-02-08 1996-09-03 Sea Engineering Associates, Inc. Tension leg platform and method of installation therefor
WO2001014687A1 (en) * 1999-08-24 2001-03-01 Aker Riser Systems As A hybrid riser configuration
WO2002063128A1 (en) * 2001-01-08 2002-08-15 Stolt Offshore Sa Marine riser tower

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5421676A (en) * 1993-02-08 1995-06-06 Sea Engineering Associates, Inc. Tension leg platform and method of instalation therefor
US5551802A (en) * 1993-02-08 1996-09-03 Sea Engineering Associates, Inc. Tension leg platform and method of installation therefor
WO2001014687A1 (en) * 1999-08-24 2001-03-01 Aker Riser Systems As A hybrid riser configuration
WO2002063128A1 (en) * 2001-01-08 2002-08-15 Stolt Offshore Sa Marine riser tower

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011099852A3 (en) * 2010-02-10 2011-12-15 Heerema Marine Contractors Nederland B.V. Method for constructing a riser assembly from a vessel and on a seabed
US8821070B2 (en) 2010-02-10 2014-09-02 Heerema Marine Contractors Nederland Se Method for constructing a riser assembly from a vessel and on a seabed
US20150000925A1 (en) * 2010-02-10 2015-01-01 Heerema Marine Contractors Nederland Se Riser assembly from a vessel and on a seabed
AU2011214986B2 (en) * 2010-02-10 2015-10-01 Heerema Marine Contractors Nederland S.E. Riser Assembly and Method For Constructing Same
AU2011214986C1 (en) * 2010-02-10 2016-01-21 Heerema Marine Contractors Nederland S.E. Riser Assembly and Method For Constructing Same
US20150047852A1 (en) * 2012-03-21 2015-02-19 Francois Regis Pionetti Installation Comprising Seabed-To-Surface Connections Of The Multi-Riser Hybrid Tower Type, Including Positive-Buoyancy Flexible Pipes
US9115543B2 (en) * 2012-03-21 2015-08-25 Saipem S.A. Installation comprising seabed-to-surface connections of the multi-riser hybrid tower type, including positive-buoyancy flexible pipes
US9482059B2 (en) 2012-04-18 2016-11-01 Acergy France SAS Jumper support arrangements for hybrid riser towers

Also Published As

Publication number Publication date
NO20020803D0 (en) 2002-02-19
NO20020803L (en) 2003-08-20
NO316635B1 (en) 2004-03-15
AU2003206450A1 (en) 2003-09-09

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