CA2681204A1 - Floating platform for operation in regions exposed to extreme weather conditions - Google Patents
Floating platform for operation in regions exposed to extreme weather conditions Download PDFInfo
- Publication number
- CA2681204A1 CA2681204A1 CA002681204A CA2681204A CA2681204A1 CA 2681204 A1 CA2681204 A1 CA 2681204A1 CA 002681204 A CA002681204 A CA 002681204A CA 2681204 A CA2681204 A CA 2681204A CA 2681204 A1 CA2681204 A1 CA 2681204A1
- Authority
- CA
- Canada
- Prior art keywords
- platform
- buoy
- anchoring
- risers
- main platform
- 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.)
- Granted
Links
- 238000004873 anchoring Methods 0.000 claims abstract description 59
- 238000005553 drilling Methods 0.000 claims abstract description 18
- 238000004519 manufacturing process Methods 0.000 claims abstract description 9
- 229930195733 hydrocarbon Natural products 0.000 claims abstract description 5
- 150000002430 hydrocarbons Chemical class 0.000 claims abstract description 5
- 238000000034 method Methods 0.000 claims abstract description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 229910000831 Steel Inorganic materials 0.000 claims description 4
- 239000010959 steel Substances 0.000 claims description 4
- 230000008878 coupling Effects 0.000 description 5
- 238000010168 coupling process Methods 0.000 description 5
- 238000005859 coupling reaction Methods 0.000 description 5
- 238000009434 installation Methods 0.000 description 5
- 238000003860 storage Methods 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000003351 stiffener Substances 0.000 description 1
- 238000012384 transportation and delivery Methods 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B35/00—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for
- B63B35/44—Floating buildings, stores, drilling platforms, or workshops, e.g. carrying water-oil separating devices
- B63B35/4413—Floating drilling platforms, e.g. carrying water-oil separating devices
-
- 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
-
- 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
- B63B21/507—Anchoring arrangements or methods for special vessels, e.g. for floating drilling platforms or dredgers with mooring turrets
- B63B21/508—Anchoring arrangements or methods for special vessels, e.g. for floating drilling platforms or dredgers with mooring turrets connected to submerged buoy
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B22/00—Buoys
- B63B22/02—Buoys specially adapted for mooring a vessel
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B35/00—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for
- B63B35/44—Floating buildings, stores, drilling platforms, or workshops, e.g. carrying water-oil separating devices
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- Ocean & Marine Engineering (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Earth Drilling (AREA)
- Soil Working Implements (AREA)
Abstract
A floating platform for drilling after or production of hydrocarbons comp rises a semi-submersible main platform (2) carrying process and/or drilling equipment at its upper surface (7), and which is designed as a vertical, ess entially flatbottomed cylinder. The main platform (2) is provided with a cen tral vertical shaft (8) which at its lower end is adapted for reception and releasable locking of an anchoring buoy (3) carrying fastening equipment for anchoring lines (10) and for risers (14, 15) and umbilicals.
Description
Floatingplatform for operation in re iog ns exposed to extreme weather conditions The invention relates to a floating platform for drilling after or production of hydrocarbons offshore, comprising a semi-submersible main platform carrying process and/or drilling equipment at its upper surface, and which is designed as a vertical, essentially flat-bottomed cylinder.
A platform designed as stated above is known from Norwegian patent No.
io 319 971. By designing the platform with a cylindrical platform body, there is obtained a substantial reduction of pitching and rolling moveinents. Further, such a platform has large carrying capacity with respect to production or drilling equipment, and a large storage capacity for oil, fuel and the like. The platform will be direction -independent with respect to environmental influence, and therefore may be anchored by means of a 1s simple fixed anchoring system. Further, risers can be connected directly to a receiving system on the platform, without any need for swivel transference or the like.
For operation in arctic regions where there is a danger for icebergs, it is a requirement that a floating platform must have the possibility for disconnection of both anchoring system and risers. When operating in regions where extreme weather occurs 20 with low frequency, for example in regions exposed to hurricanes, it may be of great advantage to be able to disconnect a floating unit, as this will be able to reduce the requirements to an anchoring system considerably.
The drawbacks of a conventional disconnection with production of hydro-carbons where anchoring lines and risers are disconnected individually, are loss of time 25 and breaks in deliveries. In addition, equipment which is to be able to be disconnected is more expensive in order to be able to take into account a possible leakage together with picking-up from the sea. A disconnection and a subsequent connection of anchoring lines and/or risers may involve several weeks of stoppage in the production of a production unit. The connection generally will require that a tender vessel is 30 engaged for picking-up of anchoring lines and risers. The connecting operation therefore will be sensitive to the weather conditions.
The object of the present invention is to provide a platform for use in regions exposed to extreme weather or where drifting ice and icebergs occur.
The above-mentioned object is achieved with a platform of the introductorily 35 stated type which, according to the invention, is characterised in that the main platform is provided with a central, vertical shaft which at its lower end is adapted for reception in releasable locking of an anchoring buoy carrying fastening equipment for anchoring lines and for risers and umbilicals.
A platform designed as stated above is known from Norwegian patent No.
io 319 971. By designing the platform with a cylindrical platform body, there is obtained a substantial reduction of pitching and rolling moveinents. Further, such a platform has large carrying capacity with respect to production or drilling equipment, and a large storage capacity for oil, fuel and the like. The platform will be direction -independent with respect to environmental influence, and therefore may be anchored by means of a 1s simple fixed anchoring system. Further, risers can be connected directly to a receiving system on the platform, without any need for swivel transference or the like.
For operation in arctic regions where there is a danger for icebergs, it is a requirement that a floating platform must have the possibility for disconnection of both anchoring system and risers. When operating in regions where extreme weather occurs 20 with low frequency, for example in regions exposed to hurricanes, it may be of great advantage to be able to disconnect a floating unit, as this will be able to reduce the requirements to an anchoring system considerably.
The drawbacks of a conventional disconnection with production of hydro-carbons where anchoring lines and risers are disconnected individually, are loss of time 25 and breaks in deliveries. In addition, equipment which is to be able to be disconnected is more expensive in order to be able to take into account a possible leakage together with picking-up from the sea. A disconnection and a subsequent connection of anchoring lines and/or risers may involve several weeks of stoppage in the production of a production unit. The connection generally will require that a tender vessel is 30 engaged for picking-up of anchoring lines and risers. The connecting operation therefore will be sensitive to the weather conditions.
The object of the present invention is to provide a platform for use in regions exposed to extreme weather or where drifting ice and icebergs occur.
The above-mentioned object is achieved with a platform of the introductorily 35 stated type which, according to the invention, is characterised in that the main platform is provided with a central, vertical shaft which at its lower end is adapted for reception in releasable locking of an anchoring buoy carrying fastening equipment for anchoring lines and for risers and umbilicals.
2 The invention will be further described below in connection with exemplary embodiments with reference to the drawings, wherein Fig. 1 shows the main platform and the anchoring buoy connected together;
Fig. 2 shows how the anchoring buoy is raised to the main platform by chain winches;
Fig. 3 shows a first embodiment of the anchoring buoy with flexible risers connected thereto;
Fig. 4 shows a second embodiment of the anchoring buoy with steel risers connected thereto;
Fig. 5 shows a top view of a set-up of anchoring lines connected to the anchoring buoy;
Fig. 6 shows the anchoring buoy lowered to a free-floating position after disconnection; and Fig. 7 shows pick-up lines extending from the anchoring buoy and floating on the water surface.
As shown in Figs. 1 and 2, the illustrated embodiment of a platform structure according to the invention comprises a main platform 2 and an anchoring unit consisting of a submerged anchoring buoy 3. The main platform 2 is designed as a vertical, essentially flat-bottomed cylinder body, in a corresponding manner as in the introductorily mentioned patent specification. The platform may have a circular or a polygonal cross-section.
As distinct from the previously known platform, the cylinder body in this case is provided with a central, vertical shaft 8 which at its lower end is adapted for reception and releasable locking of the anchoring buoy 3. The platform has double walls and possibly a double bottom that are used as ballast tanks 4. These are divided into a sufficient number of tanks to make sure that damage stability and the like is taken care of. Inside of the ballast tanks there are arranged loading tanks 5 for storage of hydrocarbons. Under a living quarter 18 on the main deck 7 there will be engine rooms and different tanks, a cofferdam etc. Equipment for the production of oil and gas, drilling equipment and different auxiliary systems are placed as modules 6 on the main deck.
As appears from Figs. 1 and 2, winches 9 are arranged in the upper part of the shaft 8, for pulling-in of the anchoring buoy 3 from a submerged position and up to the connecting position in the shaft 8. The anchoring buoy has an at least partly conical shape, for reception in a corresponding conical portion in the lower part of the shaft.
When the buoy 3 is in the correct position, it will be securely locked by a mechanical locking means (not shown). The winches 9 will also be used for connection, pre-stressing and after-tensioning of the anchoring lines (anchor chains) 10 for the platform. On the main platform there are also installed coupling manifolds for the
Fig. 2 shows how the anchoring buoy is raised to the main platform by chain winches;
Fig. 3 shows a first embodiment of the anchoring buoy with flexible risers connected thereto;
Fig. 4 shows a second embodiment of the anchoring buoy with steel risers connected thereto;
Fig. 5 shows a top view of a set-up of anchoring lines connected to the anchoring buoy;
Fig. 6 shows the anchoring buoy lowered to a free-floating position after disconnection; and Fig. 7 shows pick-up lines extending from the anchoring buoy and floating on the water surface.
As shown in Figs. 1 and 2, the illustrated embodiment of a platform structure according to the invention comprises a main platform 2 and an anchoring unit consisting of a submerged anchoring buoy 3. The main platform 2 is designed as a vertical, essentially flat-bottomed cylinder body, in a corresponding manner as in the introductorily mentioned patent specification. The platform may have a circular or a polygonal cross-section.
As distinct from the previously known platform, the cylinder body in this case is provided with a central, vertical shaft 8 which at its lower end is adapted for reception and releasable locking of the anchoring buoy 3. The platform has double walls and possibly a double bottom that are used as ballast tanks 4. These are divided into a sufficient number of tanks to make sure that damage stability and the like is taken care of. Inside of the ballast tanks there are arranged loading tanks 5 for storage of hydrocarbons. Under a living quarter 18 on the main deck 7 there will be engine rooms and different tanks, a cofferdam etc. Equipment for the production of oil and gas, drilling equipment and different auxiliary systems are placed as modules 6 on the main deck.
As appears from Figs. 1 and 2, winches 9 are arranged in the upper part of the shaft 8, for pulling-in of the anchoring buoy 3 from a submerged position and up to the connecting position in the shaft 8. The anchoring buoy has an at least partly conical shape, for reception in a corresponding conical portion in the lower part of the shaft.
When the buoy 3 is in the correct position, it will be securely locked by a mechanical locking means (not shown). The winches 9 will also be used for connection, pre-stressing and after-tensioning of the anchoring lines (anchor chains) 10 for the platform. On the main platform there are also installed coupling manifolds for the
3 transfer of well stream, and for oil and gas export. Transfer hoses will be installed between the coupling manifold and riser fastenings 20 located on the anchoring buoy.
The main platform 2 may be a passive unit which has no propulsion machinery of its own, and which has to be towed by a tender vessel to and from the position for connection, or if it has to be moved away from the current location. The main platform 2 may also be equipped with propellers (thrusters) 11 which will give the main platform the possibility to transfer itself without any assistance from a tender vessel. It may transfer itself to avoid bad weather or icebergs, and it may sail back for own machine and couple itself to the anchoring buoy 3.
The anchoring buoy 3 is a large buoyancy tank. The buoyancy tank is divided into a suitable number of cells in order to ensure that a damage does not have dramatic consequences. At the outer edge of the buoy there are placed fairleads 12 for fastening of the anchor chains 10. The anchor chains 10 extend from the fairleads and up to chain locks 13 at the top the buoy. The chain locks will carry all forces from the anchor chains 10, both when the buoy floats freely and when it is connected to the main platform 2. Risers and umbilicals 14, 15 will be connected to the buoy. If flexible risers 14 are used at "normal" water depths, there will be arranged I- or J-tubes extending through the buoy hull from the bottom to the top. The risers 14 may then be pulled in and locked fixedly at the upper edge of the buoy. Here there will be placed safety valves and the like together with coupling flenses 20 for connection of transfer hoses etc. At the bottom of the I- or J-tube there may be arranged either a bellmouth or a locking means for fastening of bend stiffeners. If steel catenary risers (SCR) 15 are used, an opening 25 will be arranged in the center of the buoy (see Fig. 4) where there is arranged a deck for suspension of the risers. The risers then will hang in a flexible joint fastened in this deck. Safety valves, coupling flanges etc. will be placed above the deck. With this arrangement the steel risers will hang freely towards the sea bed. A
similar suspension may also be used for freely hanging flexible risers 14. The flexible joint at the top then will not be required.
When installing the platform structure 1, the main platform 2 and the 3o anchoring buoy 3 will be interconnected by a mechanical locking means.
Pulling-in/adjustment of anchoring lines 10 and tensioning of lines will be as on a "conventional" unit. After pulling-in of the anchoring lines 10 they will be locked by the chain locks 13 located at the top of the anchoring buoy 3. After locking of the anchoring lines/anchor chains 10, the chain length which has been pulled on board will be placed in chain lockers 16 at the top of the anchoring buoy. At the end of some of the chains there will be mounted a pick-up line 17. The number of pick-up lines 17 depends on how the anchoring lines 10 are arranged. For the arrangement shown in Fig. 5, three pick-up lines 17 will be used, i.e. one from each group of anchoring lines 10. The pick-up lines 17 may be arranged so that they are picked up by a remotely
The main platform 2 may be a passive unit which has no propulsion machinery of its own, and which has to be towed by a tender vessel to and from the position for connection, or if it has to be moved away from the current location. The main platform 2 may also be equipped with propellers (thrusters) 11 which will give the main platform the possibility to transfer itself without any assistance from a tender vessel. It may transfer itself to avoid bad weather or icebergs, and it may sail back for own machine and couple itself to the anchoring buoy 3.
The anchoring buoy 3 is a large buoyancy tank. The buoyancy tank is divided into a suitable number of cells in order to ensure that a damage does not have dramatic consequences. At the outer edge of the buoy there are placed fairleads 12 for fastening of the anchor chains 10. The anchor chains 10 extend from the fairleads and up to chain locks 13 at the top the buoy. The chain locks will carry all forces from the anchor chains 10, both when the buoy floats freely and when it is connected to the main platform 2. Risers and umbilicals 14, 15 will be connected to the buoy. If flexible risers 14 are used at "normal" water depths, there will be arranged I- or J-tubes extending through the buoy hull from the bottom to the top. The risers 14 may then be pulled in and locked fixedly at the upper edge of the buoy. Here there will be placed safety valves and the like together with coupling flenses 20 for connection of transfer hoses etc. At the bottom of the I- or J-tube there may be arranged either a bellmouth or a locking means for fastening of bend stiffeners. If steel catenary risers (SCR) 15 are used, an opening 25 will be arranged in the center of the buoy (see Fig. 4) where there is arranged a deck for suspension of the risers. The risers then will hang in a flexible joint fastened in this deck. Safety valves, coupling flanges etc. will be placed above the deck. With this arrangement the steel risers will hang freely towards the sea bed. A
similar suspension may also be used for freely hanging flexible risers 14. The flexible joint at the top then will not be required.
When installing the platform structure 1, the main platform 2 and the 3o anchoring buoy 3 will be interconnected by a mechanical locking means.
Pulling-in/adjustment of anchoring lines 10 and tensioning of lines will be as on a "conventional" unit. After pulling-in of the anchoring lines 10 they will be locked by the chain locks 13 located at the top of the anchoring buoy 3. After locking of the anchoring lines/anchor chains 10, the chain length which has been pulled on board will be placed in chain lockers 16 at the top of the anchoring buoy. At the end of some of the chains there will be mounted a pick-up line 17. The number of pick-up lines 17 depends on how the anchoring lines 10 are arranged. For the arrangement shown in Fig. 5, three pick-up lines 17 will be used, i.e. one from each group of anchoring lines 10. The pick-up lines 17 may be arranged so that they are picked up by a remotely
4 operated vehicle (ROV) in that lines 17 with a buoyancy element are released by a hydroacoustic signal, whereafter the lines can be picked up at the water surface, or at least one line 23 may be equipped with a floating element 22 so that it lies on the surface and can be picked up.
Pulling-in and connection of risers, umbilicals, etc. will also be carried out with the anchoring buoy 3 connected. After locking of risers 14, 15, connection hoses and cables between the top of risers/cables and the manifold arrangement on the main platform 2 can be mounted in place. After connection of anchoring lines 10 and risers 14, 15 the platform structure 1 is ready for operation.
io As mentioned above, the anchoring buoy 3 in the connected position is locked to the main platform 2 by a mechanical locking means. Before a disconnection can be carried out, all connection hoses and cables between the main platform 2 and the anchoring buoy 3 must be disconnected. When this has been carried out, the anchoring buoy can be disconnected by opening the mechanical locking means. The anchoring buoy is ballasted so that it finds a position of equilibrium at a pre-determined depth D
below the water surface 24. The anchoring buoy 3 will now float in a position wherein it will only to a small extent be subjected to loads from waves. In addition, the risk for collision with vessels and possible icebergs will be reduced to a minimum.
When connecting the anchoring buoy 3, the main platform 2 will be brought to the correct position above the buoy, either unaided or by assistance from a tender vessel. A remotely operated vehicle (ROV) picks up pick-up lines 17 which are brought up inside the shaft 8 in the main platform 2. The pick-up lines 17 are connected to the chain winches 9 which are used to pull up the ends of the anchor chains 10 located in the chain lockers 16 at the top of the anchoring buoy 3, and the chains are placed on the chain winches. The pull-in is carried out in that the chain winches 9 pull in the anchoring buoy 3 with all risers, umbilicals, cables, etc.
connected to and extending down to the sea bed. When the anchoring buoy 3 is in the correct position, it is locked by the mechanical locking means. Coupling hoses, cables, etc. from the main platform 2 is connected to the anchoring buoy 3 and the production can be restarted.
Alternatively, the pick-up lines 17 will have floating buoys 21, 22 which can be released for instance by a hydroacoustic signal or which lie on the water surface and can be picked up in a conventional manner. If an arrangement with a floating pick-up line 23 is used, a line must be arranged from the shaft 8 and outwards to the side of the platform 2. The floating line 23 is then picked up from the side of the main platform 2 and is connected to said line. The buoyancy elements 21, 22 are disconnected and the interconnected lines are again dropped into the sea. The pick-up lines 17 can now be pulled up through the shaft 8 and connected to the chain winches 9. Further pulling-up and connection will be as with the use of an ROV.
When the platform structure is to be equipped with an installation for drilling after oil, such an installation requires a vertical opening through the main platform (a moon-pool) if the installation is to be placed on the deck 7 of the platform.
It will then be most suitable to use a part of a loading tank 5 as a moon-pool. When using an
Pulling-in and connection of risers, umbilicals, etc. will also be carried out with the anchoring buoy 3 connected. After locking of risers 14, 15, connection hoses and cables between the top of risers/cables and the manifold arrangement on the main platform 2 can be mounted in place. After connection of anchoring lines 10 and risers 14, 15 the platform structure 1 is ready for operation.
io As mentioned above, the anchoring buoy 3 in the connected position is locked to the main platform 2 by a mechanical locking means. Before a disconnection can be carried out, all connection hoses and cables between the main platform 2 and the anchoring buoy 3 must be disconnected. When this has been carried out, the anchoring buoy can be disconnected by opening the mechanical locking means. The anchoring buoy is ballasted so that it finds a position of equilibrium at a pre-determined depth D
below the water surface 24. The anchoring buoy 3 will now float in a position wherein it will only to a small extent be subjected to loads from waves. In addition, the risk for collision with vessels and possible icebergs will be reduced to a minimum.
When connecting the anchoring buoy 3, the main platform 2 will be brought to the correct position above the buoy, either unaided or by assistance from a tender vessel. A remotely operated vehicle (ROV) picks up pick-up lines 17 which are brought up inside the shaft 8 in the main platform 2. The pick-up lines 17 are connected to the chain winches 9 which are used to pull up the ends of the anchor chains 10 located in the chain lockers 16 at the top of the anchoring buoy 3, and the chains are placed on the chain winches. The pull-in is carried out in that the chain winches 9 pull in the anchoring buoy 3 with all risers, umbilicals, cables, etc.
connected to and extending down to the sea bed. When the anchoring buoy 3 is in the correct position, it is locked by the mechanical locking means. Coupling hoses, cables, etc. from the main platform 2 is connected to the anchoring buoy 3 and the production can be restarted.
Alternatively, the pick-up lines 17 will have floating buoys 21, 22 which can be released for instance by a hydroacoustic signal or which lie on the water surface and can be picked up in a conventional manner. If an arrangement with a floating pick-up line 23 is used, a line must be arranged from the shaft 8 and outwards to the side of the platform 2. The floating line 23 is then picked up from the side of the main platform 2 and is connected to said line. The buoyancy elements 21, 22 are disconnected and the interconnected lines are again dropped into the sea. The pick-up lines 17 can now be pulled up through the shaft 8 and connected to the chain winches 9. Further pulling-up and connection will be as with the use of an ROV.
When the platform structure is to be equipped with an installation for drilling after oil, such an installation requires a vertical opening through the main platform (a moon-pool) if the installation is to be placed on the deck 7 of the platform.
It will then be most suitable to use a part of a loading tank 5 as a moon-pool. When using an
5"internal" moon-pool, drilling risers and the like will be protected against ice and the like in exposed regions. Possible oil leakages in the moon-pool will also in a simple manner be able to be intercepted and removed.
Alternatively, the drilling installation may be placed on a cantilever platform (not shown) at the side of the main platform 2. In case of drilling operations the io anchoring lines may be adjusted in order to maintain a correct position of the platform when the weather load varies. If the platform is equipped with thrusters 11 these may be used in addition in order to maintain a best possible position while drilling.
When connecting and disconnecting the anchoring buoy 3, the drilling installation will not be involved. Drilling risers etc. will be connected after that the anchoring buoy is in the locked position. When disconnecting the anchoring buoy, drilling risers with associated valves etc. will be disconnected from the bottom and preferably raised and stored prior to disconnection.
Alternatively, the drilling installation may be placed on a cantilever platform (not shown) at the side of the main platform 2. In case of drilling operations the io anchoring lines may be adjusted in order to maintain a correct position of the platform when the weather load varies. If the platform is equipped with thrusters 11 these may be used in addition in order to maintain a best possible position while drilling.
When connecting and disconnecting the anchoring buoy 3, the drilling installation will not be involved. Drilling risers etc. will be connected after that the anchoring buoy is in the locked position. When disconnecting the anchoring buoy, drilling risers with associated valves etc. will be disconnected from the bottom and preferably raised and stored prior to disconnection.
Claims (9)
1. A floating platform for drilling after or production of hydrocarbons offshore, comprising a semi-submersible main platform (2) carrying process and/or drilling equipment at its upper surface (7), and which is designed as a vertical, essentially flat-bottomed cylinder, characterised in that the main platform (2) is provided with a central vertical shaft (8) which at its lower end is adapted for reception and releasable locking of an anchoring buoy (3) carrying fastening equipment for anchoring lines (10) and for risers (14, 15) and umbilicals.
2. A platform according claim 1, characterised in that the anchoring buoy (3) has an at least partly conical shape, for reception in a corresponding conical portion at the lower part of the shaft (8) in the main platform (2).
3. A platform according to claim 1 or 2, characterised in that the anchoring buoy (3) is provided with chain stoppers (13) and fairleads (12) placed along the outer periphery of the buoy (3).
4. A platform according to one of the claims 1-3, characterised in that the anchoring buoy (3) has an arrangement for fastening of flexible risers (14) or steel risers (15) in a central opening (25) in the buoy (3).
5. A platform according to one of the claims 1-4, characterised in that the anchoring buoy (3) is divided into ballast tanks which can be partly filled with ballast to give the buoy (3) a suitable depth (D) in the water after disconnection.
6. A platform according to one the claims 1-5, characterised in that the anchoring buoy (3) is equipped with a line arrangement (17) making it possible to connect the end of anchor chains (10) to pull-in winches (9) on the main platform (2).
7. A platform according to one of the claims 1-6, characterised in that the anchoring buoy (3) can be pull into the shaft (8) in the main platform (2) by use of the winches (9) used for pulling-in and tensioning of the anchor chains (10).
8. A platform according to one of the claims 1-7, characterised in that the main platform (2) has a vertical opening (moon-pool) in the platform hull for execution of drilling operations or other well interventions.
9. A platform according to claim 1, characterised in that the main platform (2) has a cantilever platform for the support of equipment for carrying out drilling operations or other well interventions.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NO20071491A NO20071491L (en) | 2007-03-21 | 2007-03-21 | Detachable platform for operation in exposed areas |
| NO20071491 | 2007-03-21 | ||
| PCT/NO2008/000091 WO2008115068A1 (en) | 2007-03-21 | 2008-03-12 | Floating platform for operation in regions exposed to extreme weather conditions |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2681204A1 true CA2681204A1 (en) | 2008-09-25 |
| CA2681204C CA2681204C (en) | 2014-08-05 |
Family
ID=39766102
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2681204A Active CA2681204C (en) | 2007-03-21 | 2008-03-12 | Floating platform for operation in regions exposed to extreme weather conditions |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US20100143045A1 (en) |
| EP (1) | EP2139754A4 (en) |
| KR (1) | KR101532234B1 (en) |
| CN (1) | CN101674975A (en) |
| CA (1) | CA2681204C (en) |
| NO (1) | NO20071491L (en) |
| RU (1) | RU2009138730A (en) |
| WO (1) | WO2008115068A1 (en) |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2644349C (en) | 2006-03-30 | 2014-07-08 | Exxonmobil Upstream Research Company | Mobile, year-round arctic drilling system |
| PL2093143T3 (en) * | 2008-02-19 | 2011-09-30 | Waertsilae Ship Design Germany Gmbh | Service vessel |
| CN101612982B (en) * | 2009-08-13 | 2012-05-09 | 上海利策科技有限公司 | Circular floating ocean platform capable of releasing multi-point mooring |
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| US6113314A (en) * | 1998-09-24 | 2000-09-05 | Campbell; Steven | Disconnectable tension leg platform for offshore oil production facility |
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| US7958835B2 (en) * | 2007-01-01 | 2011-06-14 | Nagan Srinivasan | Offshore floating production, storage, and off-loading vessel for use in ice-covered and clear water applications |
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2007
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2008
- 2008-03-12 CN CN200880014490A patent/CN101674975A/en active Pending
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- 2008-03-12 WO PCT/NO2008/000091 patent/WO2008115068A1/en active Application Filing
- 2008-03-12 US US12/531,785 patent/US20100143045A1/en not_active Abandoned
- 2008-03-12 KR KR1020097021880A patent/KR101532234B1/en active IP Right Grant
- 2008-03-12 RU RU2009138730/11A patent/RU2009138730A/en not_active Application Discontinuation
- 2008-03-12 EP EP08723983A patent/EP2139754A4/en not_active Withdrawn
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|---|---|
| EP2139754A4 (en) | 2012-12-12 |
| RU2009138730A (en) | 2011-04-27 |
| KR20090121403A (en) | 2009-11-25 |
| EP2139754A1 (en) | 2010-01-06 |
| KR101532234B1 (en) | 2015-06-29 |
| NO20071491L (en) | 2008-09-22 |
| WO2008115068A1 (en) | 2008-09-25 |
| CN101674975A (en) | 2010-03-17 |
| CA2681204C (en) | 2014-08-05 |
| US20100143045A1 (en) | 2010-06-10 |
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| EEER | Examination request |