CN110998028A - Seaworthiness fixation of a cantilever on a mobile offshore platform - Google Patents

Seaworthiness fixation of a cantilever on a mobile offshore platform Download PDF

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Publication number
CN110998028A
CN110998028A CN201880053856.1A CN201880053856A CN110998028A CN 110998028 A CN110998028 A CN 110998028A CN 201880053856 A CN201880053856 A CN 201880053856A CN 110998028 A CN110998028 A CN 110998028A
Authority
CN
China
Prior art keywords
platform
cantilever
seaworthy
distal
boom
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.)
Pending
Application number
CN201880053856.1A
Other languages
Chinese (zh)
Inventor
科内鲁斯·韦尔杜
雷内·亚历山大·范罗森
雷内·德布鲁金
文森佐·弗朗西斯科·莫雷洛
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GustoMSC Resources BV
Original Assignee
GustoMSC Resources BV
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
Priority to NL2019115 priority Critical
Priority to NL2019115A priority patent/NL2019115B1/en
Application filed by GustoMSC Resources BV filed Critical GustoMSC Resources BV
Priority to PCT/NL2018/050399 priority patent/WO2018236214A1/en
Publication of CN110998028A publication Critical patent/CN110998028A/en
Pending legal-status Critical Current

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Classifications

    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02BHYDRAULIC ENGINEERING
    • E02B17/00Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
    • E02B17/02Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor placed by lowering the supporting construction to the bottom, e.g. with subsequent fixing thereto
    • E02B17/021Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor placed by lowering the supporting construction to the bottom, e.g. with subsequent fixing thereto with relative movement between supporting construction and platform
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B15/00Supports for the drilling machine, e.g. derricks or masts
    • E21B15/003Supports for the drilling machine, e.g. derricks or masts adapted to be moved on their substructure, e.g. with skidding means; adapted to drill a plurality of wells
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B15/00Supports for the drilling machine, e.g. derricks or masts
    • E21B15/02Supports for the drilling machine, e.g. derricks or masts specially adapted for underwater drilling

Abstract

A mobile offshore platform has a boom movable between an extended position and a retracted position and a movement system having a first guide mounted to the boom and oriented parallel to the boom, a second guide mounted to the platform hull and oriented transverse to the boom, and at least one support skid for guiding movement along the first and second guides. Proximal seaworthy fixtures are provided for holding the retracted booms in place relative to the platform hull. Distal seaworthy fixtures are provided for holding the retracted booms in place relative to the platform hull. When in the seaworthy secured state, the first retaining portion of the distal seaworthy securing device and the second retaining portion of the distal seaworthy securing device engage one another at a location below the cantilever at the platform hull. A method for the suspension of an airworthiness fixed platform is also described.

Description

Seaworthiness fixation of a cantilever on a mobile offshore platform
Technical Field
The present invention relates to a mobile offshore platform that is convertible between a floating state for displacement between operating positions and a stationary state supported by the sea floor. One example of such a mobile offshore platform is a jack-up rig having a jack-up hull that can be lifted to its fixed operating position at sea using legs that are first lowered to the sea floor and then the hull of the rig is lifted along the legs. To move to a new operating position, the platform hull is lowered until it floats, and then the legs are raised as much as possible to reduce drag when the tug pulls the rig or the rig is driven by its own drive.
Background
In a floating state, the mobile offshore platform is a vessel and thus moves due to the waves and surges exposed to the sea surface, while in a stationary state, the platform legs rest on the sea floor so that the platform moves very little.
Such mobile offshore platforms may for example be used for drilling hydrocarbons or installing offshore structures. In order to perform drilling operations, a drill floor and a drilling derrick are typically placed at the rear (distal) end of the cantilever structure. The entire cantilever can be moved relative to the platform hull of the mobile offshore platform using an X-Y movement system, allowing the drilling derrick to be placed precisely over the drilling location in a larger area at the rear of the platform hull without the need to displace the drilling rig, which would require lowering and jacking the platform hull. Mobile offshore platforms with a movement system allowing extension and retraction in the longitudinal (X) direction of the cantilever and pivoting of the cantilever about a vertical axis are also known.
An example of such a mobile offshore platform with such a mobile system is described in US 6171027. A longitudinal rail oriented in a direction designated as the X-direction is attached to the cantilever, and a transverse rail oriented in a direction designated as the Y-direction perpendicular to the X-direction is attached to the upwardly facing side of the platform hull (typically the main deck).
A support member between the cantilever and the platform deck for supporting the cantilever relative to the platform deck is provided in the form of a support ramp and is guided for movement in the Y-direction on the guide rail, while the support ramp supports and guides the cantilever for movement in the X-direction of the cantilever as the guide rail moves on the support ramp. The supporting runners can slide on the guide rails or have rollers that roll on the guide rails. The movement system drive may be, for example, a hydraulic cylinder or a rack and pinion type. The support skids also constitute spacers so that the level of the cantilever above the main deck is relatively high, thereby making more vertical space above the main deck available for other items and reducing the height to which the platform hull must be lifted in order to work over existing jackets.
When the rig is to be brought into a floating state, the cantilever is retracted and a seaworthy fixation has to be made to prevent the cantilever from moving relative to the platform hull due to the motions of the floating hull in waves and surges (pitch, roll and yaw). At the forward (proximal) end, the retracted jib is constrained against movement relative to the platform hull in both the longitudinal and transverse directions by a pin extending through holes in the forward end portion of each of the two longitudinal jib rails and in the support structure on the platform hull. The front end of the cantilever is held in place in both the X and Y directions by keeping corresponding holes in the guide rail and the support structure aligned with each other.
In addition to the seaworthy fixation at the forward end of the boom, the aft end (distal end) of the boom must also be seaworthy to avoid the boom pivoting about its forward end, which would cause damage to the attachment of the forward end. One known solution for airworthiness fixing the rear end of the cantilever is to provide a strut bridging the vertical separation between the cantilever and the main deck and extending from an eyelet at the lower deck level at the rear end of the cantilever to an anchor point at one of the ends of the rear transverse deck rail.
Due to their size and weight, such columns are difficult and time consuming to handle during installation and removal. When not used as an airworthiness fixation of the cantilever, it can be removed so as to cause a risk of dropping and swaying of the object, or it can remain attached to the cantilever, which can have an adverse effect on the remaining maximum allowed cantilever load.
Disclosure of Invention
It is an object of the present invention to provide a solution for seaworthy fixation of a boom of a mobile offshore platform, which is easier to handle during installation and dismantling, avoids the risk of objects falling or shaking, has less impact on the allowed boom loads when put in place, and allows a fully remote or automatic seaworthy fixation of the boom in a simple way.
According to the present invention, this object is achieved by providing a mobile offshore platform according to claim 1. In another embodiment, the object is achieved by carrying out the airworthiness fastening method according to claim 16.
Since in the seaworthy securing state the first retaining portion of the distal seaworthy securing means and the second retaining portion of the distal seaworthy securing means engage each other, said first retaining portion of the distal seaworthy securing means and the second retaining portion of the distal seaworthy securing means are secured to the platform hull at a position below the cantilever, the seaworthy securing means can be very compact and easy to operate.
Specific details and embodiments of the invention are set forth in the dependent claims.
Other features, effects and details of the invention appear from the detailed description and the accompanying drawings.
Drawings
FIG. 1 is a schematic side view of one example of a platform standing on the seafloor with the cantilever in a partially extended position according to the present invention;
FIG. 2 is a schematic top plan view of the platform according to FIG. 1 with the cantilever in a fully extended position;
figure 3 is a schematic side view of a part of the platform according to figures 1 and 2, including parts of the cantilever and platform hull in a fully retracted state;
FIG. 4 is a schematic top plan view of the platform according to FIGS. 1-3 with the cantilever in a fully retracted position;
figure 5 is a schematic top plan view of a portion of the lower deck of the cantilever at the distal end of the cantilever of the platform according to figures 1 to 4;
FIG. 6 is a schematic side sectional view taken along the plane VI-VI in FIG. 5;
FIG. 7 is a top plan view of a portion of a cross rail of the platform according to FIGS. 1-6;
FIG. 8 is a schematic side sectional view taken along plane VIII-VIII in FIG. 7;
FIG. 9 is a schematic side sectional view taken along plane IX-IX in FIG. 7; and
fig. 10 is a schematic side sectional view taken along the plane X-X in fig. 4.
Detailed Description
In the drawings, an example of a mobile offshore platform 1 according to the invention is shown. The platform has a platform hull 2 allowing the platform to float and three legs 3 movably guided relative to the platform hull 2 for vertical movement relative to the platform hull 2. In order to drive the movement of the legs 3 between a lowered operating position, as shown in fig. 1, in which the platform hull 2 is lifted from the floating level, and a transport position (not shown), in which the main part of the legs 3 project above the floating platform hull 2, leg drivers 4 are provided.
The platform 1 also has an elongated cantilever 5 which is movable in the longitudinal manner X of the cantilever 5 between an extended position (fig. 1 and 2) and a retracted position (fig. 3, 4, 6, 8, 9, 10). At the distal end 7 of the cantilever 5, a drilling mast 6 (only shown in fig. 1, in other top views only the corners of the mast are shown) is mounted on the cantilever 5. Other devices may be provided at the distal end 7 of the boom 5 depending on the operation to be performed. The moonpool deck 8 of the cantilever 5 is located at a lower level than the rest of the cantilever 5. In this example, the distal end 7 of the boom 5 constitutes the aft end of the boom 5, as the boom 5 projects to the aft of the platform hull 2 when in the extended state. The distal end of the cantilever may also constitute the forward or lateral end of the cantilever, respectively, if the cantilever projects forward or at the side of the platform hull.
In order to move the boom 5 in the longitudinal direction X and the transverse direction Y relative to the platform hull 2, a movement system is provided. In this example, the movement system is a sliding system. The sliding system is formed by a first guide 9, a second guide 10 and a support member, wherein the first guide 9 is mounted to the boom 5 and is oriented in a direction X parallel to the boom 5 for guiding the movement of the boom 5 in a longitudinal direction X, the second guide 10 is mounted to the platform housing 2 and is oriented in a direction Y transverse to the boom 5 and the longitudinal direction X for guiding the movement of the boom 5 in a direction Y transverse to the boom 5, and the support means are in the form of support runners 11, 12, 13, 14, each arranged to guide the movement along the first guide 9 and the second guide 10. When sliding the boom 5 in the transverse direction Y, the bearing runners 11 to 14 extend along the second guide 10. When sliding the boom 5 in the longitudinal direction X, the first guide 9 extends on the support runners 11 to 14.
When the platform 1 is in a transport state, in which the platform hull 2 is floating on the water surface, the cantilever 5 must be seaworthy fixed to the platform hull 2 to prevent the cantilever 5 from moving relative to the platform hull 2 due to the movement of the platform hull 2 caused by waves, surges and winds. For seaworthy fixation of the boom 5 at the proximal (here forward) end 15 of the boom 5, proximal seaworthy fixation means 16 are provided at the proximal end portion of the boom 5 for holding the boom 5 in a retracted position relative to the platform hull 2. As best shown in fig. 10, in this example, the proximal seaworthy fixation device 16 is formed by a tongue 17 at the proximal end of the cantilever 5 and is received in a hole 19 in a bracket 18. The holes 19 each have a lower boundary in the form of a guide support plate 20, which guide support plate 20 flares downwards in a rearward direction for guiding a chamfered front end 21 of the respective tongue 17 into the hole 19 as the boom 5 approaches its retracted position, so that the sliding system at least partially relieves the bending load caused by the fact that most of the retracted boom 5 is located in front of the support runners 11 to 14. A pin 22 is inserted through aligned holes 23 to 26 of each of the tongue 17 and the hole 19 to retain the tongue 17 in their position in the hole 19. Thus, the proximal end of the retracted boom 5 is held firmly in place in the seaworthy fixation state by the proximal seaworthy fixation device 16. The skilled person will note that alternative solutions for airworthiness fixation of the proximal boom end may be provided, such as a pin protruding into a hole in the front end portion of the rail extending in the longitudinal manner of the boom.
However, this is not sufficient to prevent the distal end 7 of the cantilever 5 from moving too far in the transverse direction Y, especially when sea conditions are severe or high. Thus, the platform 1 is also equipped with distal seaworthy fixtures 27 at the distal ends of the proximal seaworthy fixtures 16 for holding the booms 5 in place in a retracted position relative to the platform hull 2. When in the seaworthy securing state, the first retaining portion 28 of the distal seaworthy securing device 27 engages with the second retaining portion 29 of the distal seaworthy securing device 27 at a position below the cantilever 5, which second retaining portion 29 is secured to the platform hull 2. This makes the distal seaworthy fixation device 27 very light and compact and easy to handle and operate during fixation and release of the boom 5. Thus, it improves the operability, security and capabilities of the platform. Due to its low weight, the first holding portion 28 of the distal seaworthy fixation device 27 has very little effect on the allowed cantilever loads. It should be noted that embodiments are also conceivable in which the second holding portion engages the first engaging portion or in which the robot engaging portions engage each other.
The first retaining portion 28 of the distal seaworthy fixation device 27 is mounted to the cantilever 5. Thus, the boom 5 is held directly in place by the distal seaworthy fixing means 27, which is stronger than the distal end of the boom 5 being held in place in the transverse direction Y by one or more of the support skids 11 to 14, the dimensions of the support skids 11 to 14 not being such as to resist the seaworthy fixing loads, or requiring very large dimensions, in particular for the tilting loads that have to be resisted and transmitted by the guiding structure.
In addition, since the first holding section 28 of the distal seaworthy fixation device 27 is mounted to the lower part of the cantilever 5 (in this case the moonpool deck 8) protruding downwards with respect to the more proximal part of the cantilever 5, a very secure seaworthy fixation of the distal end of the cantilever 5 is achieved. In this position, the distal seaworthy fixation device 27 need only bridge a relatively small gap between the cantilever 5 and the platform hull 2.
The gap to be bridged can be particularly small, since the first holding portion 28 of the distal seaworthy fixation device 27 is mounted at a lower position than the first guide 9. Nevertheless, since the first retaining portion 28 of the distal seaworthy fixation device 27 is mounted in a lateral position on the support runners 13, 14, the support runners 13, 14 engage the same rail of the second guide 9 in the lateral direction Y, thus leaving room for the support runners 11 to 14.
The first guide 9 and the second guide 10 are each constituted by a pair of guide rails 30, 31, 32, 33, which allow precise and stable guidance of the boom 5 during sliding.
The distal seaworthy fixation device 27 in the fastened state engages with one of the rails 32, 33 of the second guide 10, in this example the one of the rails 32, 33 which is closest to the stern of the platform hull 2. Engagement with the guide rail 32 closest to the outside of the platform 1 allows the boom 5 to be held near its distal end, which is advantageous for a secure airworthiness fixation. In addition, this avoids the need to pass the lowermost part of the downwardly projecting boom 5 until over most of the platform hull 2 immediately above the second guide 10 when retracting the boom 5 to its maximum retracted position.
When the platform is floating in rough sea waves, the cantilever 5 and the platform hull 2 tend to bend slightly. As in the present example, if the boom 5 is fixed at its proximal end 15 against movement in the longitudinal direction X relative to the platform hull 2, the bending of the boom 5 and the platform hull 2 may be accommodated for example by: securing the boom 5 by the distal seaworthy securing means 27 allows some displacement of the boom 5 in the longitudinal direction relative to the platform hull 2 when in position to hold the boom 5 in a retracted position relative to the platform hull 2.
As shown in fig. 5 to 9, the allowed displacement of the boom 5 in the longitudinal direction X relative to the platform hull 2 is larger within the longitudinal gap (sum of the first open spaces 34 in the longitudinal direction X) than the transverse gap (sum of the second open spaces 35 in the transverse direction Y), if any, so as to allow a larger displacement of the boom 5 in the longitudinal direction X relative to the platform hull 2 than in the transverse direction Y, if any. Preferably, the gap in the X direction is greater than 10mm, and for added preference, the gap in the X direction may be greater than 20mm, 30mm or 40 mm. Preferably, the gap in the X direction is less than 150mm, more preferably less than 120 mm. Preferably, the gap in the Y direction is less than 10mm, and for increasing preference, the gap in the Y direction may be less than 5mm or 2 mm. Preferably, the gap in the Y direction is greater than 0.25 mm.
In this example, this is achieved by the following settings: the first retaining portion 28 of the distal seaworthy fixation device 27 is a pin 28 that protrudes into the second retaining portion 29 when the distal seaworthy fixation device 27 is in a seaworthy fixation state, and the second retaining portion 29 is a hole 29. More specifically, the size of the hole 29 allows the longitudinal movement of the pin 28 with respect to the guide rail 32 and limits the lateral movement of the pin 28 completely or at least more strictly than the movement in the longitudinal direction X. The substantially rectangular shape of the aperture 29 and the distal end of the pin 28 provide a greater load transfer surface area in the lateral direction than the clearance in the vertical direction provided by a circular or other circular shape.
At least the lower end of the pin 28 to be inserted into the hole 29 and the hole 29 have respective shapes having a relatively close fit in the transverse direction Y, while leaving a significant clearance in the longitudinal direction X to prevent the pin 28 from being subjected to longitudinal loads. The upper part of the pin 28 has a larger cross-sectional dimension than the lower end, providing a shoulder 46, which shoulder 46 determines the vertical movement of the pin 28 towards the guide 10 during the airworthiness fixing, so that the depth of the hole 29 and the vertical distance between the cantilever 5 and the guide 10 do not have to meet tight tolerances. In addition, the lower end of the pin and the opening may thus be relatively small, so that the structural integrity of the guide rail is only impaired to a small extent, while the upper part of the pin may have a relatively large cross-section, so that the pin has a large bending strength.
In order to make the distal seaworthy fixation device 27 particularly easy to operate, the distal seaworthy fixation device 27 comprises a pin actuator 36 for moving the pin 28 between an extended position, in which the pin 28 extends into the hole 29, and a retracted position, in which the pin 28 is retracted out of the hole 29. The pin actuator 36 may be in the form of a linear motor, spindle drive, or hydraulic cylinder, for example. Additionally or alternatively, a manually operated spindle may be provided.
The pin or the hole may have a tapered portion or an actuated wedging portion may be inserted into the hole to cause wedging engagement between the pin and the hole in the transverse direction to achieve zero clearance in the transverse direction.
A pin 28 is mounted to the boom 5, and a pin receiving hole 29 is provided in the second guide 10. This allows the movable parts to be arranged on the underside of the cantilever 5 where these parts are relatively well shielded from the weather, especially in the case of pins in the cantilever, and are not easily damaged during operation on the platform deck.
The pin actuator 28 is preferably arranged to urge the pin 28 towards the extended position, for example by gravity and/or spring force, such that if the hole 29 is in line with the pin 28, the pin 28 enters the hole 29. Thus, the cantilever 5 can simply be slid slowly in the lateral direction until the pin 28 snaps into the hole 29 and does not have to be slid to a position where the pin 28 and the hole 29 are aligned with a certain precision.
Depending on the size and weight of the cantilever, the distal seaworthy fixation device may provide engagement between its first and second retaining portions at one or more locations below the cantilever.
As best shown in fig. 5 and 6, by arranging the pin 28 between the beams 37 to 40 of the moonpool deck 8 and aligned with the longitudinal beams 41, 42 along the moonpool 43, the position of the pin 28 in the cantilever 5 is optimized to transfer loads to the cantilever 5. The moonpool deck 8 is partially provided with a reinforcement plate 44, the reinforcement plate 44 having an opening 45 allowing the pin 28 to protrude.
When seaworthy boom 5 is secured, boom 5 is first retracted and laterally aligned with bracket 18 for seaworthy securement at proximal end 15 of boom 5. After the cantilever 5 is fixed at its proximal end 15, the cantilever may be moved laterally at its distal end until the first and second retaining portions of the distal seaworthy fixation device are aligned to allow mutual engagement. Then, the pin 28 of the distal airworthiness fixture 27 is lowered or released to descend so as to come into contact with the rail 32 of the second guide 10. The sliding system can also be used to slowly align the first and second holding portions of the distal seaworthy fixation device in the transverse direction Y, for seaworthy fixation at its distal end 7, and to automatically drop or drive the pin 28 into the receiving hole 29 when the pin 28 is aligned with the receiving hole 29. The pin 28 can be pushed continuously in the engagement direction under a slight pretension.
Within the framework of the invention, many variations and alternatives on the examples described are conceivable. For example, the pins 28 of the distal seaworthy fixtures may be positioned on or in the platform hull, with the pins extending from the platform hull to the boom to be received in holes or other pin engaging structures provided as part of the boom. The pins may be held and driven by a device in the form of a separate structure attached to the platform hull or the boom, or the device may be integrated with the platform hull structure or the boom structure.
Various features have been described as part of the illustrated example or alternative embodiments. It should be understood, however, that the scope of the present invention also includes embodiments having combinations of all or some of the features of the embodiments in addition to the specific combinations of features presented in the embodiments. Moreover, the described effects and advantages of a feature are generally applicable to the feature to which they pertain, and not only in the context of the examples or in combination with other described features.

Claims (17)

1. A mobile offshore platform, comprising:
a platform hull allowing the platform to float;
at least three legs movably guided relative to the platform hull for vertical movement relative to the platform hull;
a leg drive for driving the legs between a lowered operating position in which the platform hull is jacked from a floating level and a transport position in which a major portion of the legs project above the floating platform hull;
an elongated cantilever movable in a longitudinal direction of the cantilever between an extended position and a retracted position;
a mobile system, comprising:
a first guide mounted to the boom and oriented parallel to the boom,
for guiding the cantilever movement in the longitudinal direction;
a second guide mounted to the platform hull and oriented transverse to the cantilever for guiding the cantilever movement in a direction transverse to the cantilever; and
at least one support runner arranged for being arranged along the first guide and the first guide
A second guide member guides the movement;
a proximal seaworthy fixture at a proximal end of the boom for holding the boom in place in the retracted position relative to the platform hull; and
a distal seaworthy fixation device, distal to the proximal seaworthy fixation device, for holding the boom in place in the retracted position relative to the platform hull, wherein, when in a seaworthy fixation state, a first retaining portion of the distal seaworthy fixation device and a second retaining portion of the distal seaworthy fixation device are engaged with one another at a position below the boom in a fixed position relative to the platform hull.
2. The platform of claim 1, wherein the first retaining portion of the distal seaworthy fixation device is mounted to the cantilever.
3. The platform of claim 2, wherein the first retaining portion of the distal seaworthy fixation device is mounted to a lower portion of the cantilever that protrudes downward relative to a more proximal portion of the cantilever.
4. The platform of claim 3, wherein the first retaining portion of the distal seaworthy fixation device is mounted in a position below the first guide.
5. The platform of claim 4, in which the first retaining portion of the distal seaworthy fixation device is mounted in a lateral position to the at least one support runner.
6. The platform according to any one of the preceding claims, wherein at least the first guide or the second guide is constituted by at least one guide rail.
7. The platform of claim 6, wherein at least the first guide or the second guide is comprised of a pair of rails.
8. The platform of claim 7 in which the second guide is comprised of a pair of rails and in which a first retaining portion of the distal seaworthy fixture in a fastened state engages one of the rails of the second guide closest to a proximal most side of the platform hull.
9. The platform of any one of claims 2 to 8 in which the distal fastening means allows the cantilever to be displaced in a longitudinal direction relative to the platform hull when in position to hold the cantilever in the retracted position relative to the platform hull.
10. The platform of claim 9, wherein the allowed displacement of the cantilever relative to the platform hull in the longitudinal direction is within a gap that is greater than a gap, if any, that allows displacement of the cantilever relative to the platform hull in the transverse direction.
11. The platform of any one of the preceding claims, wherein the first retaining portion of the distal seaworthy fixation device is a pin protruding into a hole when the distal seaworthy fixation device is in a seaworthy fixation state.
12. The platform of claim 11, wherein the distal seaworthy fixation device comprises a pin actuator for moving the pin between an extended position protruding into the hole and a retracted position retracted out of the hole.
13. The platform of claim 12, wherein at least the pin, the hole, or a wedging portion that is insertable with the pin into the hole has a tapered portion for causing wedging engagement between the pin and the hole.
14. The platform of any one of claims 11 to 13 in which the pin is mounted to the cantilever and the pin receiving hole is provided in the second guide.
15. The platform of claim 12 or 13 and claim 14, wherein the pin actuator is arranged to cause the pin to be urged towards the extended position such that the pin enters the hole with the hole in line with the pin.
16. A method for airworthiness securing a cantilever of a mobile offshore platform, the mobile offshore platform comprising:
a platform hull allowing the platform to float;
at least three legs movably guided relative to the platform hull for vertical movement relative to the platform hull;
a leg drive for driving the legs between a lowered operating position in which the platform hull is jacked from a floating level and a transport position in which a major portion of the legs project above the floating platform hull;
an elongated cantilever movable in a longitudinal direction of the cantilever between an extended position and a retracted position; and
a mobile system, comprising:
a first guide mounted to the boom and oriented parallel to the boom for guiding the boom movement in the longitudinal direction;
a second guide mounted to the platform hull and oriented transverse to the cantilever for guiding the cantilever movement in a direction transverse to the cantilever; and
at least one support runner arranged for being arranged along the first guide and the first guide
A second guide member guides the movement;
wherein, the cantilever carries out the airworthiness fixedly through following mode:
securing a proximal portion of the boom relative to the platform hull to maintain the boom in the retracted position relative to the platform hull; and
securing a distal end portion of the boom relative to the platform hull using a distal seaworthy securing means distal from a proximal seaworthy securing means for holding the boom in position relative to the platform hull in the retracted position by causing interengagement between a first retaining portion of the distal seaworthy securing means and a second retaining portion of the distal seaworthy securing means in a fixed position relative to the platform hull in a position below the boom.
17. The method of claim 16, further comprising after the proximal end portion is fixed relative to the hull and before the distal end portion is fixed relative to the hull, laterally moving the distal end portion of the boom until the first retention portion of the distal seaworthy fixation device and the second retention portion of the distal seaworthy fixation device reach alignment.
CN201880053856.1A 2017-06-23 2018-06-21 Seaworthiness fixation of a cantilever on a mobile offshore platform Pending CN110998028A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
NL2019115 2017-06-23
NL2019115A NL2019115B1 (en) 2017-06-23 2017-06-23 Seafastening of a cantilever on a mobile offshore platform
PCT/NL2018/050399 WO2018236214A1 (en) 2017-06-23 2018-06-21 Seafastening of a cantilever on a mobile offshore platform

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Publication Number Publication Date
CN110998028A true CN110998028A (en) 2020-04-10

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CN (1) CN110998028A (en)
NL (1) NL2019115B1 (en)
SG (1) SG11201912885YA (en)
WO (1) WO2018236214A1 (en)

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NL2022730B1 (en) * 2019-03-12 2020-09-18 Itrec Bv Offshore system

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