CA2723410C - Floating platform and method for operation thereof - Google Patents
Floating platform and method for operation thereof Download PDFInfo
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- CA2723410C CA2723410C CA2723410A CA2723410A CA2723410C CA 2723410 C CA2723410 C CA 2723410C CA 2723410 A CA2723410 A CA 2723410A CA 2723410 A CA2723410 A CA 2723410A CA 2723410 C CA2723410 C CA 2723410C
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- 238000000034 method Methods 0.000 title claims abstract description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 49
- 239000003643 water by type Substances 0.000 claims abstract description 25
- 238000004519 manufacturing process Methods 0.000 claims abstract description 10
- 238000003860 storage Methods 0.000 claims abstract description 9
- 238000005553 drilling Methods 0.000 claims abstract description 8
- 230000005484 gravity Effects 0.000 claims abstract description 6
- 230000003467 diminishing effect Effects 0.000 claims abstract description 4
- 238000004873 anchoring Methods 0.000 claims description 9
- 238000010276 construction Methods 0.000 description 7
- 230000009286 beneficial effect Effects 0.000 description 6
- 238000009434 installation Methods 0.000 description 4
- 230000001133 acceleration Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229930195733 hydrocarbon Natural products 0.000 description 3
- 150000002430 hydrocarbons Chemical class 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- 230000009191 jumping Effects 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 230000004308 accommodation Effects 0.000 description 1
- 239000012634 fragment Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000005304 joining Methods 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000005406 washing 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
- B63B2211/00—Applications
- B63B2211/06—Operation in ice-infested waters
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B2241/00—Design characteristics
- B63B2241/02—Design characterised by particular shapes
- B63B2241/04—Design characterised by particular shapes by particular cross sections
- B63B2241/06—Design characterised by particular shapes by particular cross sections circular
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- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- Ocean & Marine Engineering (AREA)
- Earth Drilling (AREA)
- Piles And Underground Anchors (AREA)
- Testing Or Calibration Of Command Recording Devices (AREA)
- Other Liquid Machine Or Engine Such As Wave Power Use (AREA)
Abstract
Floating platform for drilling, production, storage or other applications, particularly suitable for icy waters, which platform comprising a hull with outer side wall which is mainly symmetrical around a vertical centre axis in the platform and in a lower end is closed with a bottom, a deck in the upper end of the hull equipped conveniently according to the intended application, the platforms draught being considerably less than the diameter of the platform and the buoyancy centre for the platform for the submerged part is situated lower than the centre of gravity of the platform, characterized by that the mainly symmetrical outer side of the hull includes at least three sections counted from the upper part of the hull: a water level section with diminishing diameter in the direction downwards along the centre axis, in which water level section the water level should be positioned during operation in icy waters, an intermediate section with cylinder form and an under section with increasing diameter in the direction downwards along the centre axis. Method for operation in icy waters of the platform.
Description
Floating platform and method for operation thereof Area of the invention The present invention relates to floating platforms and particularly floating platforms applicable for operation in exposed waters.
Background of the invention and prior art For drilling for hydrocarbons, production and storage of produced hydrocarbons at sea and other applications, a wide range of concepts are used.
One of the concepts is to use a floating installation, which could be a vessel, a semi-submersible or floating platform. In the Patent publication NO 319971 is described an offshore platform for drilling for, or production of, hydrocarbons. Further it is is described a platform designed as vertical, mainly flat bottomed cylinder, characterized by the platform body in the lower part of the cylinder is equipped with at least one peripheral, circular cut out defined by a ring member below the cut out and that the diameter of the platform body is considerably larger than its draught and buoyancy centre of the submerged part of the platform is lower than the centre of gravity of the platform. Such a construction has shown to have advantageous large capacity both for storage of oil and load capacity on deck. Further the cost of the construction is low, the assembly period short and it is achieved large flexibility for different applications.
Such a platform may be positioned by scattered anchoring and neither a turret nor a swivel are needed to handle risers/hoses and anchoring lines. The round or mainly rounded cross section is beneficial due to that rotation according to weather is not necessary and it has been shown that the movement and stresses on the platform is surprisingly low compared with other types of floating installations. Thus the level of stretch and tension are limited. The form of the hull provides a compact construction which contribute to the wave loads only having a limited degree of influence on tension 3o and stretch forces.
There is, however, a need for a further improved version of such a floating platform, particularly a platform which is particularly suitable for utilization in icy waters, in addition to other waters.
Summery of the invention The above mentioned need is meet by the present invention providing a floating platform for drilling, production, storage or other applications, particularly in icy waters, the platform comprising
Background of the invention and prior art For drilling for hydrocarbons, production and storage of produced hydrocarbons at sea and other applications, a wide range of concepts are used.
One of the concepts is to use a floating installation, which could be a vessel, a semi-submersible or floating platform. In the Patent publication NO 319971 is described an offshore platform for drilling for, or production of, hydrocarbons. Further it is is described a platform designed as vertical, mainly flat bottomed cylinder, characterized by the platform body in the lower part of the cylinder is equipped with at least one peripheral, circular cut out defined by a ring member below the cut out and that the diameter of the platform body is considerably larger than its draught and buoyancy centre of the submerged part of the platform is lower than the centre of gravity of the platform. Such a construction has shown to have advantageous large capacity both for storage of oil and load capacity on deck. Further the cost of the construction is low, the assembly period short and it is achieved large flexibility for different applications.
Such a platform may be positioned by scattered anchoring and neither a turret nor a swivel are needed to handle risers/hoses and anchoring lines. The round or mainly rounded cross section is beneficial due to that rotation according to weather is not necessary and it has been shown that the movement and stresses on the platform is surprisingly low compared with other types of floating installations. Thus the level of stretch and tension are limited. The form of the hull provides a compact construction which contribute to the wave loads only having a limited degree of influence on tension 3o and stretch forces.
There is, however, a need for a further improved version of such a floating platform, particularly a platform which is particularly suitable for utilization in icy waters, in addition to other waters.
Summery of the invention The above mentioned need is meet by the present invention providing a floating platform for drilling, production, storage or other applications, particularly in icy waters, the platform comprising
2 a hull with outer sidewalls mainly positioned rotation symmetrically around a vertical centre axis in the platform and in a lower part closed by a bottom, a deck in the upper end of the hull equipped suitably according to the intended application, the platforms draught being considerably less than the diameter of the platform and the buoyancy centre of the platform for the submerged part is positioned lower than the centre of gravity of the platform.
The platform according to the invention is characterized by its mainly symmetrically outer side of the hull includes at least three sections 1 o counted from the upper end of the hull:
a waterline section with diminishing diameter in the direction downwards along the centre axis, in which water level section the water level of the sea is to be located during operation in icy waters, an intermediate section with cylinder form and an under section with increasing diameter in the direction downwards along the centre axis.
Since the hull is mainly symmetrical around a vertical centre axis of the platform, implies that the hull is round or nearly round in the form defined by the outer sidewall. An outer sidewall of polygonal form, such as an assembly of many joining, flat sheets along the peripheral, is meant to be comprised in the term mainly symmetrical around a centre axis.
The ratio between the platforms draughts and diameter at water level is preferably 0.2-0.3 during operation in non-icy waters, were the water level can be added to the intermediate section of the hull. By operation in icy waters the ratio between the draughts of the platform and diameter at the water level is preferably approximately 0.3-0.4. A generally preferred ratio is about 0.3.
The water level section has preferably an inclination inward in downward direction of about 45 , which is considered preferable with regard to icebreaking and the prevailing forces. The inclination in the under section is preferably approximately 45 outwardly, as seen in the direction downwards, which is considered to be preferable with regard to the handling and transport of ice radial away from the platform. The under section contribute to give the ice a movement preventing it to be led under the hull. Other inclinations may, however, also be applicable. The transition between the sections can be sharp or gliding, so that the form can resemble an hourglass or an inner part of a laying U. Typical dimensions of the sections is a water level section with height of 10-15 m, an intermediate section with height 5-15 m and an under section with height 2-4 m. The dimensions of the sections can be beyond the above and depend on the ice thickness and other expected ice conditions in the scheduled operational area as well as the size and draught of the platform.
The platform according to the invention is characterized by its mainly symmetrically outer side of the hull includes at least three sections 1 o counted from the upper end of the hull:
a waterline section with diminishing diameter in the direction downwards along the centre axis, in which water level section the water level of the sea is to be located during operation in icy waters, an intermediate section with cylinder form and an under section with increasing diameter in the direction downwards along the centre axis.
Since the hull is mainly symmetrical around a vertical centre axis of the platform, implies that the hull is round or nearly round in the form defined by the outer sidewall. An outer sidewall of polygonal form, such as an assembly of many joining, flat sheets along the peripheral, is meant to be comprised in the term mainly symmetrical around a centre axis.
The ratio between the platforms draughts and diameter at water level is preferably 0.2-0.3 during operation in non-icy waters, were the water level can be added to the intermediate section of the hull. By operation in icy waters the ratio between the draughts of the platform and diameter at the water level is preferably approximately 0.3-0.4. A generally preferred ratio is about 0.3.
The water level section has preferably an inclination inward in downward direction of about 45 , which is considered preferable with regard to icebreaking and the prevailing forces. The inclination in the under section is preferably approximately 45 outwardly, as seen in the direction downwards, which is considered to be preferable with regard to the handling and transport of ice radial away from the platform. The under section contribute to give the ice a movement preventing it to be led under the hull. Other inclinations may, however, also be applicable. The transition between the sections can be sharp or gliding, so that the form can resemble an hourglass or an inner part of a laying U. Typical dimensions of the sections is a water level section with height of 10-15 m, an intermediate section with height 5-15 m and an under section with height 2-4 m. The dimensions of the sections can be beyond the above and depend on the ice thickness and other expected ice conditions in the scheduled operational area as well as the size and draught of the platform.
3 For a production and/or storage device the platform comprises preferably a removable, downward extending body (connecting member), coaxially located with the platforms vertical centre axis, withdrawn from the lower edge of the outer sidewall for attachment and/or through-guiding of anchoring lines, chains, risers, and/or cables and with inherit buoyancy. For icy waters such a removable member is preferred, because risers, houses, cables, anchoring lines and chains are pulled away from the pherimeter and thus protected from the ice and exposed connecting area is pulled down a distance under the bottom of the platform. Any ice entering under the platform must be moved a fair distance inward towards the centre of the platform for the area of attachment is 1o reached so that the ice probably must be raised to the bottom of the platform and not hitting any risers, anchoring lines etc. Should a large iceberg arrive, the connecting member can be detached; whereupon it will sink down to the safe depth determined by the balance between the buoyancy of the connecting member and the weight of attached devices. The removable connecting member is extending at least 10 in below the bottom of the platform before the area for attachment/through-guiding of the risers is met.
For some applications of the platform, particularly at deep waters, it is not necessary with anchoring and for some applications neither any removable connecting member. Dynamic positioning may be used for positioning of the floating platform for some applications, for instance during drilling at deep waters.
With the present invention a method is also provided for operation in icy waters with a floating platform according to the present invention, characterized by the platform is ballasted so that the water level is situated in the water level section during the operation of integrated devices for ballasting.
Comprehensive testing of the floating platform according to the invention in various scales and for a wide spectrum of conditions, has shown surprisingly positive results.
Figures The present invention as well as advantageous of it, are illustrated by means of four figures, of which:
Fig. 1 shows a view of a floating platform according to the invention, figures 2, 3 and 4 show comparable data between the round, vertically standing Sevan-platforms of which the present platform is one type, a semi-submersible platform and a vessel, respectively, in that fig. 2 illustrates data for heave movement, fig. 3 illustrates data for pitch movements and fig. 4. illustrates data for rolling movements.
For some applications of the platform, particularly at deep waters, it is not necessary with anchoring and for some applications neither any removable connecting member. Dynamic positioning may be used for positioning of the floating platform for some applications, for instance during drilling at deep waters.
With the present invention a method is also provided for operation in icy waters with a floating platform according to the present invention, characterized by the platform is ballasted so that the water level is situated in the water level section during the operation of integrated devices for ballasting.
Comprehensive testing of the floating platform according to the invention in various scales and for a wide spectrum of conditions, has shown surprisingly positive results.
Figures The present invention as well as advantageous of it, are illustrated by means of four figures, of which:
Fig. 1 shows a view of a floating platform according to the invention, figures 2, 3 and 4 show comparable data between the round, vertically standing Sevan-platforms of which the present platform is one type, a semi-submersible platform and a vessel, respectively, in that fig. 2 illustrates data for heave movement, fig. 3 illustrates data for pitch movements and fig. 4. illustrates data for rolling movements.
4 Detailed description Reference is made to fig. 1 which in a side view illustrates a floating platform according to the present invention. Further is illustrated a floating platform 1, comprising a hull 2 which is mainly symmetrical around a vertical centre axis in the platform and in a lower end closed by a bottom 3. A deck 4 is illustrated in an upper end of the hull equipped suitably according to the intended use. It would clearly appear from the figure that the draught of the platform is considerably less than the diameter of the platform. What is not so obvious is that the centre of buoyancy for the submerged part of the platform is lower than the centre of gravity of the platform. It io clearly appears that the-rotation symmetrical outer side of the hull 2 includes at least three sections counted from the upper end of the hull, namely:
a water level section 5 with diminishing diameter in the direction downwards along the centre axis, in which water level section, the water level of the sea is situated during operation in icy waters, a intermediate section 6 with a cylinder form, and an under section 7 with increasing diameter in the direction downwards along the centre axis.
In the direction downward the water level section inclines inwardly towards the centre axis approximately 45 , while the under section inclines outwardly about 45 . The ratio between draught and diameter of the platform at the water level is approximately 0.3. Further is illustrated a removable, downwardly extending member (connecting member) 8, coaxially located with the platforms vertical centre axis and withdrawn such that it is positioned far from the outer side walls lower edge of the hull.
The connecting member 8 is for connecting risers, anchoring lines/chains, hoses, cables and similar, as needed. The connecting area for risers is at least 10 m lower than the bottom of the platform, which is beneficial in icy waters.
During operation in icy waters, the platform is ballasted so that the water level is at the water level section. Further, it is considered beneficial to position the water level so that an upper edge of the level is meeting in the upper part of the water level section. During operation in non-icy waters the ballasting can be such that the water level is in the intermediate section 6 having a cylinder form, in that a cylinder form with vertical sides at the water level gives less movements for the platform.
The floating platform can have many applications and is equipped conveniently according to the intended application both on deck and inside.
Further, the platform can be used as an FPSO (Floating Production Storage Offloading), a FPU
(Floating Production Unit), a MODU (Mobile Offshore Drilling Unit), a MSV
(Multipurpose Support Vessel), a FLNG (Floating Liquified Natural Gas Production), a GTW (Gas Through Wire, that is an offshore power plant), a FDPSO (Floating Drilling Production Storage Offloading), a FAU (Floating Accommodation Unit, that is a residential quarter), or other applications.
The generally known advantages of the platform construction with regard to movement in turbulent waters, is illustrated in the figures 2, 3 and 4. In figure 2 is
a water level section 5 with diminishing diameter in the direction downwards along the centre axis, in which water level section, the water level of the sea is situated during operation in icy waters, a intermediate section 6 with a cylinder form, and an under section 7 with increasing diameter in the direction downwards along the centre axis.
In the direction downward the water level section inclines inwardly towards the centre axis approximately 45 , while the under section inclines outwardly about 45 . The ratio between draught and diameter of the platform at the water level is approximately 0.3. Further is illustrated a removable, downwardly extending member (connecting member) 8, coaxially located with the platforms vertical centre axis and withdrawn such that it is positioned far from the outer side walls lower edge of the hull.
The connecting member 8 is for connecting risers, anchoring lines/chains, hoses, cables and similar, as needed. The connecting area for risers is at least 10 m lower than the bottom of the platform, which is beneficial in icy waters.
During operation in icy waters, the platform is ballasted so that the water level is at the water level section. Further, it is considered beneficial to position the water level so that an upper edge of the level is meeting in the upper part of the water level section. During operation in non-icy waters the ballasting can be such that the water level is in the intermediate section 6 having a cylinder form, in that a cylinder form with vertical sides at the water level gives less movements for the platform.
The floating platform can have many applications and is equipped conveniently according to the intended application both on deck and inside.
Further, the platform can be used as an FPSO (Floating Production Storage Offloading), a FPU
(Floating Production Unit), a MODU (Mobile Offshore Drilling Unit), a MSV
(Multipurpose Support Vessel), a FLNG (Floating Liquified Natural Gas Production), a GTW (Gas Through Wire, that is an offshore power plant), a FDPSO (Floating Drilling Production Storage Offloading), a FAU (Floating Accommodation Unit, that is a residential quarter), or other applications.
The generally known advantages of the platform construction with regard to movement in turbulent waters, is illustrated in the figures 2, 3 and 4. In figure 2 is
5 viewed curves of heaveheave-movements for standing rotational symmetrical platforms (Sevan) and semi-submersible platforms and vessel with waves coming in from the front from the side of the vessel, respectively. In figure 3 is illustrated pitch under similar conditions for a Sevan platform, a semi-submersible platform with sea coming in from the front and a vessel with sea coming in from the front and clearly that the io general Sevan construction is beneficial under many operating conditions.
In figure 4 is viewed rolling of similar, floating installations at corresponding conditions and it is clearly seen that the Sevan construction has very beneficial properties closely followed by the semi-submersible installation while a vessel has considerably more rolling, comparably.
Due to very limited storage and load capacity, as well as little applicability in icy waters, semi-submersible platforms cannot be compared with the present, floating platform, because the functionality is insufficient.
As mentioned it was found at comprehensive testing that the properties for the floating platform according to the invention is surprisingly beneficial in icy waters.
Further testing was conducted with ice driving towards a platform model in the scale of 1:40. In icy waters it is, as mentioned, compulsary that the water level is at the water level section, which means that the ice naturally will be broken down in the downwards direction towards the hull. At the same time the hull will endure a force which has a component in the direction upwards. Without the desire to be bound by any theory, it is assumed that incoming ice is applying a force against and accumulating towards the platform so that the platform is lifted somewhat on the side facing the driving ice (windward side) until the moment due to buoyancy of the platform becomes stronger than the moment applied by the ice. The platform is thus rocking or pitching around a horizontal axis, but the construction of the platform entails that by rocking the platform the moment due to buoyancy is increasing considerably faster than the moment applied by the ice, which entails very moderate movement and this effect is considered to be particularly pronounced with the water level in the water level section. When a certain amount of ice is accumulated towards the side of the water level sections, a power balance will be achieved but the inherent ability of the platform to correct the moment due to buoyancy will be changed considerably by the centre of buoyancy being moved considerably to the side (the distance between the centre of gravity and buoyancy centre is increasing), which entails that the platform is rocking/rotating back to the starting position while the ice is broken up and diverged in the direction downwards.
The movement of the water current and the platform motion guide the ice downwards
In figure 4 is viewed rolling of similar, floating installations at corresponding conditions and it is clearly seen that the Sevan construction has very beneficial properties closely followed by the semi-submersible installation while a vessel has considerably more rolling, comparably.
Due to very limited storage and load capacity, as well as little applicability in icy waters, semi-submersible platforms cannot be compared with the present, floating platform, because the functionality is insufficient.
As mentioned it was found at comprehensive testing that the properties for the floating platform according to the invention is surprisingly beneficial in icy waters.
Further testing was conducted with ice driving towards a platform model in the scale of 1:40. In icy waters it is, as mentioned, compulsary that the water level is at the water level section, which means that the ice naturally will be broken down in the downwards direction towards the hull. At the same time the hull will endure a force which has a component in the direction upwards. Without the desire to be bound by any theory, it is assumed that incoming ice is applying a force against and accumulating towards the platform so that the platform is lifted somewhat on the side facing the driving ice (windward side) until the moment due to buoyancy of the platform becomes stronger than the moment applied by the ice. The platform is thus rocking or pitching around a horizontal axis, but the construction of the platform entails that by rocking the platform the moment due to buoyancy is increasing considerably faster than the moment applied by the ice, which entails very moderate movement and this effect is considered to be particularly pronounced with the water level in the water level section. When a certain amount of ice is accumulated towards the side of the water level sections, a power balance will be achieved but the inherent ability of the platform to correct the moment due to buoyancy will be changed considerably by the centre of buoyancy being moved considerably to the side (the distance between the centre of gravity and buoyancy centre is increasing), which entails that the platform is rocking/rotating back to the starting position while the ice is broken up and diverged in the direction downwards.
The movement of the water current and the platform motion guide the ice downwards
6 along the intermediate section whereupon the ice by the water current is lead further down along the under section and diverged in the direction away from the centre axis, along the outer surface of the under section. Thus the ice is bent/broken down, is guided down and guided in the direction back against the direction of the driving ice whereupon the ice is floating up again as smaller fragments and lead around the platform by means of the increased velocity of the water current near the platform wall.
The ice is broken very efficiently and moved efficiently around the platform without doing any damage. The moderate rocking movements of the platform contribute to a reduced friction between the ice fragments and the platform in that a radially outward io directed water current is created when the platform swings back again. The swinging movement or the heave movement seems to adapt a natural frequency. The velocity of the water current is higher around the platform than the surrounding water because the water will have to follow the way around the platform. This contributes to the ice fragments being transported on a "water cushion" around the platform. However, the water currents hitting the platform can also be split in a current passing under the platform, particularly for a large platform, because it means a shorter or easier path for the current then all the way around the platform. This may lead to ice fragments under the platform, which is undesirable, but the shape of the under section has proved to be efficient to prevent ice under the platform as mentioned above, in addition to contribute to an improved "water cushion" effect.
The behaviour of the platform under icy conditions has been measured and filmed, which approves that it typically has heave movement not exceeding 6 even at 100 years first year ice condition in Arctic and very small accelerations in all degrees of freedom. It should be mentioned that other floating platform concepts have proved to have large unacceptable movements at similar ice loads in the form of "jumping"
movements with high accelerations at times. Both movements and amount of ice accumulating towards the present platform are very low, in that "jumping"
movements and high accelerations are almost absent.
The platform is preferably equipped with propulsion for operating on 3o assembling, which propulsion preferably also is adapted for utilization for propeller washing in the area around the under section with effect towards the surface at the wind board side and outwards towards the sides.
The ice is broken very efficiently and moved efficiently around the platform without doing any damage. The moderate rocking movements of the platform contribute to a reduced friction between the ice fragments and the platform in that a radially outward io directed water current is created when the platform swings back again. The swinging movement or the heave movement seems to adapt a natural frequency. The velocity of the water current is higher around the platform than the surrounding water because the water will have to follow the way around the platform. This contributes to the ice fragments being transported on a "water cushion" around the platform. However, the water currents hitting the platform can also be split in a current passing under the platform, particularly for a large platform, because it means a shorter or easier path for the current then all the way around the platform. This may lead to ice fragments under the platform, which is undesirable, but the shape of the under section has proved to be efficient to prevent ice under the platform as mentioned above, in addition to contribute to an improved "water cushion" effect.
The behaviour of the platform under icy conditions has been measured and filmed, which approves that it typically has heave movement not exceeding 6 even at 100 years first year ice condition in Arctic and very small accelerations in all degrees of freedom. It should be mentioned that other floating platform concepts have proved to have large unacceptable movements at similar ice loads in the form of "jumping"
movements with high accelerations at times. Both movements and amount of ice accumulating towards the present platform are very low, in that "jumping"
movements and high accelerations are almost absent.
The platform is preferably equipped with propulsion for operating on 3o assembling, which propulsion preferably also is adapted for utilization for propeller washing in the area around the under section with effect towards the surface at the wind board side and outwards towards the sides.
Claims (8)
1. A floating platform suitable for icy waters, comprising:
- a hull with outer side walls which is mainly symmetrical around a vertical centre axis of the platform and at a lower end is closed by a bottom, - a deck in the upper end of the hull, - the platform draught is less than a diameter of the platform and a centre of buoyancy of the platform for the submerged part is situated lower than a centre of gravity of the platform, characterized in that:
- the mainly symmetrical outer side of the hull includes at least three sections counted from the upper end of the hull:
- a water level section with diminishing diameter in the direction downwards along the centre axis, in which water level section a water level is situated during operation in icy waters, - a cylindrical intermediate section and - an under section with increasing diameter in the direction downwards along the centre axis, - the platform further comprises ballasting means configured for selectively raising or lowering the platform hull in the water so that the water level is situated in the water level section or in the intermediate section; and - the platform further comprises a removable downwardly extending member with inherent buoyancy, coaxially located with the vertical centre axis of the platform and withdrawn from a lower edge of the outer side walls.
- a hull with outer side walls which is mainly symmetrical around a vertical centre axis of the platform and at a lower end is closed by a bottom, - a deck in the upper end of the hull, - the platform draught is less than a diameter of the platform and a centre of buoyancy of the platform for the submerged part is situated lower than a centre of gravity of the platform, characterized in that:
- the mainly symmetrical outer side of the hull includes at least three sections counted from the upper end of the hull:
- a water level section with diminishing diameter in the direction downwards along the centre axis, in which water level section a water level is situated during operation in icy waters, - a cylindrical intermediate section and - an under section with increasing diameter in the direction downwards along the centre axis, - the platform further comprises ballasting means configured for selectively raising or lowering the platform hull in the water so that the water level is situated in the water level section or in the intermediate section; and - the platform further comprises a removable downwardly extending member with inherent buoyancy, coaxially located with the vertical centre axis of the platform and withdrawn from a lower edge of the outer side walls.
2. The platform according to claim 1, characterized in that the ratio between the draught of the platform and the diameter at the water level is approximately 0.3.
3. The platform according to claim 1, characterized in that the water level section has an inclination inwards in a downward direction of approximately 45 .
4. The platform according to claim 1, characterized in that the inclination of the under section is approximately 45° outwardly, viewed in the downward direction.
5. The platform of claim 1, wherein the removable downwardly extending member is a connecting member for attachment and/or through guiding of anchoring lines, chains, risers and/or cables.
6. The platform according to claim 1 or claim 5, characterized in that the removable downwardly extending member is extending below the bottom of the platform before an area for attaching/through guiding of risers and anchoring lines are found.
7. The platform of any one of the claims 1 to 6, wherein the floating platform is a drilling platform, a production platform or a storage platform.
8. A method of operating the floating platform as defined by any one of claims 1 to 7, characterized by, depending on whether the platform is in icy waters or not, operating an integrated ballasting device in the platform to selectively raise or lower the platform hull in the water so that the water level is situated in the water level section or in the intermediate section.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NO20082189A NO336984B1 (en) | 2008-05-09 | 2008-05-09 | Liquid platform and method of operation thereof |
| NONO20082189 | 2008-05-09 | ||
| PCT/NO2009/000177 WO2009136799A1 (en) | 2008-05-09 | 2009-05-08 | Floating platform and method for operation thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2723410A1 CA2723410A1 (en) | 2009-11-12 |
| CA2723410C true CA2723410C (en) | 2015-04-14 |
Family
ID=41264743
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2723410A Active CA2723410C (en) | 2008-05-09 | 2009-05-08 | Floating platform and method for operation thereof |
Country Status (6)
| Country | Link |
|---|---|
| CN (1) | CN102015436B (en) |
| CA (1) | CA2723410C (en) |
| DK (1) | DK179027B1 (en) |
| NO (1) | NO336984B1 (en) |
| RU (1) | RU2502629C2 (en) |
| WO (1) | WO2009136799A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10196114B2 (en) | 2015-05-13 | 2019-02-05 | Crondall Energy Consultants Ltd. | Floating production unit and method of installing a floating production unit |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10093394B2 (en) | 2009-11-08 | 2018-10-09 | Jurong Shipyard Pte Ltd. | Method for offshore floating petroleum production, storage and offloading with a buoyant structure |
| US9180941B1 (en) | 2009-11-08 | 2015-11-10 | Jurong Shipyard Pte Ltd. | Method using a floatable offshore depot |
| US9266587B1 (en) | 2009-11-08 | 2016-02-23 | Jurong Shipyard Pte Ltd. | Floating vessel |
| US8662000B2 (en) | 2009-11-08 | 2014-03-04 | Ssp Technologies, Inc. | Stable offshore floating depot |
| LT5806B (en) | 2010-06-29 | 2012-02-27 | Rimantas Varanauskas | Energy free floating platform and its wheel system |
| RU2591780C2 (en) * | 2010-07-08 | 2016-07-20 | Итрек Б.В. | Semisubmersible floating base and operation method thereof |
| NO20110173A1 (en) * | 2011-02-01 | 2012-08-02 | Sevan Marine Asa | Production unit suitable for use of dry valve trees |
| NO336206B1 (en) | 2011-02-01 | 2015-06-15 | Sevan Marine Asa | Production unit with butchered hanging riser and with custom hull and moonpool |
| CN103085946B (en) * | 2012-10-15 | 2016-04-13 | 大连理工大学 | Docking circular table Floating Production oil storage system |
| NO339535B1 (en) * | 2013-01-11 | 2016-12-27 | Moss Maritime As | Floating unit and method for reducing stomping and rolling movements of a floating unit |
| GB2507370B (en) | 2013-05-15 | 2014-10-15 | Atkins Ltd | Compact floating production, storage and offloading facility |
| WO2015057333A1 (en) * | 2013-10-15 | 2015-04-23 | Exxonmobil Upstream Research Company | Arctic rapid disconnect and reconnect floating drilling unit |
| AU2016223268B2 (en) * | 2015-02-24 | 2020-01-23 | Jurong Shipyard Pte Ltd. | Floating vessel |
| RU2591110C1 (en) * | 2015-03-02 | 2016-07-10 | Федеральное государственное унитарное предприятие "Крыловский государственный научный центр" | Sea floating process platform for drilling and/or production and storage in ice conditions |
| CN108995778A (en) * | 2018-08-17 | 2018-12-14 | 招商局重工（江苏）有限公司 | A kind of floating drilling platform being suitble in polar region ice formation and severe sea condition |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US1029013A (en) * | 1909-03-22 | 1912-06-11 | Springfield Metallic Casket Company | Coffin-fastener. |
| US3766874A (en) * | 1971-07-29 | 1973-10-23 | Gen Dynamics Corp | Moored barge for arctic offshore oil drilling |
| CA1042274A (en) * | 1975-04-14 | 1978-11-14 | Richard W. Slocum | Mooring system for semisubmersible drilling platform |
| US4048943A (en) * | 1976-05-27 | 1977-09-20 | Exxon Production Research Company | Arctic caisson |
| SU943090A1 (en) * | 1980-07-03 | 1982-07-15 | За витель | Semi-submerged floating platform for operation in ice |
| JPS57191188A (en) * | 1981-05-21 | 1982-11-24 | Mitsui Eng & Shipbuild Co Ltd | Floating type structure in frozen sea |
| CA1162442A (en) * | 1982-03-17 | 1984-02-21 | Brian D. Wright | Arctic barge drilling unit |
| US4434741A (en) * | 1982-03-22 | 1984-03-06 | Gulf Canada Limited | Arctic barge drilling unit |
| FI82112C (en) * | 1982-06-15 | 1991-01-10 | Masa Yards Oy | Protection procedure and device |
| GB2185446B (en) * | 1986-01-17 | 1989-10-25 | Shell Int Research | Semi-submersible vessel |
| NO319971B1 (en) * | 2001-05-10 | 2005-10-03 | Sevan Marine As | Offshore platform for drilling for or producing hydrocarbons |
| RU2213882C2 (en) * | 2001-07-23 | 2003-10-10 | Пикуль Вадим Николаевич | Method of operation of power-generating semi- submersible platform |
| MXPA05004043A (en) * | 2002-10-16 | 2005-08-18 | Single Buoy Moorings | Riser installation vessel and method of using the same. |
| NO330955B1 (en) * | 2003-04-30 | 2011-08-22 | Torp Tech As | Unloading and cargo evaporation device for ships |
| 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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2008
- 2008-05-09 NO NO20082189A patent/NO336984B1/en unknown
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2009
- 2009-05-08 WO PCT/NO2009/000177 patent/WO2009136799A1/en active Application Filing
- 2009-05-08 RU RU2010150346/11A patent/RU2502629C2/en active
- 2009-05-08 CN CN200980115983.0A patent/CN102015436B/en active Active
- 2009-05-08 CA CA2723410A patent/CA2723410C/en active Active
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2010
- 2010-01-11 DK DKPA201070011A patent/DK179027B1/en active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10196114B2 (en) | 2015-05-13 | 2019-02-05 | Crondall Energy Consultants Ltd. | Floating production unit and method of installing a floating production unit |
Also Published As
| Publication number | Publication date |
|---|---|
| DK179027B1 (en) | 2017-09-04 |
| DK201070011A (en) | 2010-03-09 |
| RU2502629C2 (en) | 2013-12-27 |
| WO2009136799A1 (en) | 2009-11-12 |
| NO20082189L (en) | 2009-11-10 |
| CN102015436B (en) | 2015-10-21 |
| NO336984B1 (en) | 2015-12-07 |
| RU2010150346A (en) | 2012-06-20 |
| CA2723410A1 (en) | 2009-11-12 |
| CN102015436A (en) | 2011-04-13 |
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