Offshore platform layout.

专利摘要:

公开号:NL1007432A1
申请号:NL1007432
申请日:1997-11-03
公开日:1998-05-08
发明作者:Roy Malcolm Bennett
申请人:Roy Malcolm Bennett；
IPC主号:

专利说明:

Title: * Offshore platform layout
The present invention relates to an offshore platform device known as a lifting platform. These vessels are used for production, exploration drilling for oil or gas, or for offshore maintenance.
The device uses a floating hull with three or four tubular or lattice legs, which can be round, square or triangular.
Most lifting platform structures use straight, i.e. vertical legs. The legs support the platform during use, and the legs are supported by the platform during transportation.
Once the legs are placed on the sea bed, lifting of the hull to the working height is accomplished by lifting devices installed at each corner of the platform. These may be rack and pinion systems or hydraulic lift systems that use frictional clamps or pins that engage holes spaced at regular intervals along the legs.
The present invention utilizes angled legs which is an improvement over the straight leg construction due to the reduced load in the legs due to wind and wave forces, the improved tilt resistance, and the reduced lateral movement of the platform. However, lifting the hull on oblique legs creates a load on the legs that is added to the load due to operational or storm design conditions. An example is known from U.S. Patent 5,092,712.
The present invention aims to eliminate or reduce this additional load.
The invention accordingly provides an offshore platform device as defined in claim 1.
One embodiment is provided with a sliding lower leg guide arranged in the four corners of the trunk, a divided collar guide arranged in the feet which makes it possible to lift the trunk to its working height without bending the legs. The sliding bottom guide does not use springs or other flexible devices to absorb leg loads during hull lift and storm loading, while the rotational freedom of the guides allows smooth lifting due to the uniform alignment of the guides on the hull. legs if the angle of inclination of the legs changes. Therefore, no limitation is imposed on the working height (or free space), which is therefore a great improvement over the prior art.
An embodiment of the present invention is described below, by way of example only, with reference to the accompanying drawings, in which:
Fig. 1 shows a view of the platform in transport conditions with the legs fully raised and the hull in floating condition;
Fig. 2 shows a view of the platform with the hull raised to its working height and the feet embedded in the ocean floor;
Fig. 3 shows a top view of the platform;
Fig. 4 shows the change in the inclination of the legs, which occurs when the trunk is raised to its working height, normally about 2-3 °;
Fig. 5 shows one of the upper guides of the platform, which is fixed and cannot move horizontally, but allows pivoting movement. The four segments of the guide are each shown with their own pivot pin,
Fig. 5A is a view of the upper guide in a direction parallel to the axis of the pivot pins;
Fig. 6 is a plan view of one of the lower guides adapted to slide horizontally in one direction but capable of responding to loads of the leg in a direction orthogonal or perpendicular to the slide direction;
Fig. 6A is a view of one of the lower guides in a direction parallel to the axis of the pivot pins;
Fig. 6B is an end view of the lower guides showing the guide installed in the hull support structure on each side of the guide;
Fig. 6C shows the position of the lower leg guides on the platform corners, and their direction of movement when the platform is raised or lowered;
Fig. 7 shows a section through the platform showing the fixed top and sliding bottom guides and the pivot attachment to the foundation;
Fig. 8 shows a cross section of the leg foundation;
Fig. 9 shows a top view of the leg foundation;
Fig. 10, 11 and 12 show the divided collar guidance of the legs at different stages of engagement.
The preferred embodiment provides a lifting platform (Fig. 1 to 3) with inclined legs 10 inclined at a fixed angle of 5 to 10 degrees that allows lifting of the hull 12 to a predetermined free height above the sea surface without bending moments in the legs cause.
Reference is now made to Fig. 4 for the description of lifting the hull.
The platform is towed to its location and the legs 10 are sunk to the seabed 14. During the sinking phase of the legs, the sliding bottom guides are locked in position to ensure that the legs 10 touch the seabed 14 at the correct angle of inclination. The locking mechanism can be mechanical or hydraulic. Penetrating the feet 18 is accomplished by transferring the water from the interior of the feet or by using the body ballast water.
With the legs 10 fully inserted, the lower guide locking mechanism 16 is disengaged before the start of the trunk lift.
In Fig. 4 it is shown that as the body 12 rises horizontally, the angle of inclination of the legs gradually decreases.
The present invention allows for unimpeded changes in the inclination of the legs by sliding the lower trunk guide horizontally and pivoting the base of the legs in a recess provided in the feet. In some embodiments, it may be preferable to use a fixed bottom guide and adjust the top guide for horizontal sliding.
When the usual free height is obtained, the locking mechanism for the lower guide 16 is actuated so that all legs 10 can withstand the same amount of load caused by storm wind and wave load. The split collar guides 20 (Figures 10 to 12) are arranged on the top of the recess in the feet 18 to fix the legs 10 to the seabed 14, which reduces the bending moments on the bottom guide.
5 and 5A show the preferred construction for the upper leg guides 22. It includes four coupling elements 24 pivotally connected to the platform and unable to translate relative to it. The coupling elements 24 hold one of the legs 10 so that it can slide and pivot therein about a single axis as a result of the pivoting of the coupling elements 24.
Fig. 6, 6A, 6B and 6C show the construction of the lower leg guide 16 in detail. It comprises four coupling elements corresponding to the coupling elements 24 of the upper guides 22. The main difference is that the coupling elements 26 are provided with a sliding mechanism, as indicated by the arrow in fig. 6 and 6C. The degree of sliding is usually in the range of 12.5 to 25 cm (5 to 10 inches). To promote sliding, the sliding mechanism may be provided with friction reducing agents such as roller bearings, a friction reducing fabric or low friction surfaces.
The movement of the sliding mechanism can run along a slight curvature.
In an alternative embodiment, pivoting coupling elements are not provided. The legs are placed in bores that allow some rotation of the legs. This alternative construction will be immediately clear to the skilled person. "
Fig. 7 shows how the angle of inclination of the legs 10 can be changed due to the adjustment of the coupling mechanisms 16, 22.
Fig. 7 to 9 schematically show the construction of the feet 18. As will be apparent, the legs 10 fit loosely into their respective feet to allow the legs to pivot when the feet 18 are anchored in the sea bed.
Referring to Figs. 10, 11 and 12, Fig. 10 shows the left segment of the divided collar 20 fitted in the recess in the foot 18. The purpose of this arrangement is to ensure that the foot is properly aligned with the leg 10 during embedding the foot.
Fig. 11 shows the left segment in a retracted position allowing the legs 10 to rotate freely in the recess in the foot during the lifting of the trunk.
Fig. 12 shows both segments of the divided collar 20 disposed in the recess in the foot.
The present invention provides for pivot or rotation of the legs 10 as they pass through the trunk 12, and also to relieve the rotating leg mount at the leg-foot connection during the lift phase.
Lifting the hull can be done by any well-known mechanism. For example, lifting pinions cooperating with toothed racks mounted on the legs 10 can be provided.
Fig. 12 shows that the fixation of the rotation achieved after lifting at the feet 18 contributes to the reduction of horizontal platform movements and foot responses due to overturning moments due to the wind wave forces.
In another embodiment, in lifting platforms that are frequently moved, the legs 10 and feet 18 may be integrally welded together. The bottom surface can be conical or pointed in this case in order to avoid large clamping moments of the supporting bottom which could cause great forces on the upper guides during lifting.
In a further embodiment, deeper water structures may include legs 10 with pointed ends that simply burrow into the sea bed. Once installed, these can be tilted freely, as required during the lifting procedure. Once the device has been lifted into position, anchor means can be mounted on each leg to position the legs against lateral displacement.
In an alternative embodiment, the guides 16 and 22 provide a loose fit to the legs 10 and pivotal coupling elements are unnecessary.
It will be understood that the top and bottom guides 22, 16 can be modified so that the top guides slide and the bottom are fixed.
It is clear that within the scope of the invention various variations and additions to the above described embodiments are possible, which are to be considered only in connection with the claims.

权利要求:
Claims (1)
[1]
1. Offshore platform arrangement, comprising a series of angled legs and a platform supported by the legs and two vertically spaced bearings mounted on the platform for each leg, the first of said bearings being a laterally fixed position and has a single degree of rotational freedom in an inclination direction of the legs and the other of said bearings has a single degree of translation freedom lateral in the plane of the platform and radial to the inclination direction of the leg, as well as a rotational freedom in the inclination direction of the leg, further including the other of said bearings such that, when these bearings are not locked, a substantially frictionless movement with respect to said single degree of translation freedom is possible.

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同族专利:

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公开号 | 公开日

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US5954454A|1999-09-21|

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NL1007432C2|1998-05-20|

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GB9622938D0|1997-01-08|

引用文献:

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公开号 | 申请日 | 公开日 | 申请人 | 专利标题

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WO1999058769A1|1998-05-11|1999-11-18|Spacelift Offshore B.V.|Tilting jack offshore platform|US2954676A|1957-05-13|1960-10-04|Jersey Prod Res Co|Lifting assembly for structures|

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US4657437A|1985-01-11|1987-04-14|Breeden John O|Mobile, offshore, self-elevating support system with adjustable leg inclination and fixation|

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US5092712A|1990-06-07|1992-03-03|Jerome Goldman|Inclined leg jack-up platform with flexible leg guides|US6099207A|1997-07-11|2000-08-08|Bennett; Roy M.|Offshore platform assembly|

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US7138038B1|2004-02-23|2006-11-21|James N Britton|Expandable anode pod|

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US7594781B1|2007-06-01|2009-09-29|Ronald Sanders|Lift boat leg|

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KR101242506B1|2010-12-27|2013-03-12|재단법인 포항산업과학연구원|Tension leg platform having stationary buoyance holding by tendon and movable buoyance|

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KR101242675B1|2012-05-04|2013-03-12|명일정공|Jack-up barge having an improved performance to prevent shake|

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FR3003324B1|2013-03-15|2015-03-13|Nov Blm|DEVICE FOR THE MANEUVER IN TRANSLATION OF A MOBILE STRUCTURE IN RELATION TO A FIXED SUPPORT|

法律状态:
1998-07-01| AD1B| A search report has been drawn up|

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1998-08-03| PD2B| A search report has been drawn up|

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2004-08-02| VD1| Lapsed due to non-payment of the annual fee|Effective date: 20040601 |

优先权:

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申请号 | 申请日 | 专利标题

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GB9622938|1996-11-04|

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GBGB9622938.0A|GB9622938D0|1996-11-04|1996-11-04|Offshore platform assembly|

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