CN1035782C

CN1035782C - Offshore structures

Info

Publication number: CN1035782C
Application number: CN93106711A
Authority: CN
Inventors: 默里·查尔斯·弗格森
Original assignee: Port Moss Marine Construction Co; Kvaerner Earl and Wright
Current assignee: Port Moss Marine Construction Co; Kvaerner Earl and Wright
Priority date: 1992-06-02
Filing date: 1993-06-02
Publication date: 1997-09-03
Anticipated expiration: 2013-06-02
Also published as: DE4318321A1; AU664448B2; GB2267525B; GB9311365D0; AU3994893A; DK61293D0; CN1079521A; NL9300899A; MY131366A; DK61293A; GB2267525A

Abstract

An offshore structure (e.g. for an offshore loading tower) having a central column arranged to extend vertically upwards when the structure is installed offshore, and in which there are at least three feet adapted to rest on a seabed and at least three legs extending upwardly and inwardly from respective feet to an apex which is below the wave effected zone when the structure is installed offshore, the apex of the legs supports an intermediate point on the height of the column, and a lower point on the height of the column is stabilised by bracing extending from positions on the at least three legs between the feet and the apex, such that the lower end of the column is supported a significant distance above the seabed.

Description

A kind of lower support structure with marine structure of a central post

The present invention relates to marine structure, relate in particular to a kind of lower support structure with marine structure of a central post.

The exploitation of offshore oil and gas field has promoted to be used to support the design of the building of drilling well, oil recovery and load bearing equipment.The fluctuation of energy prices has caused the demand to perfect as far as possible marine structure.

For large-scale deck loads, gravity platform or have the steel conduit frame of a plurality of support columns to be used as economic substructure.Yet,, proved that now with the substructure that single post constituted that penetrates the sea be very attractive to quite light deck loads.This single-column substructure has been intended to develop the oil gas field in sea, north and south and Australian coastal waters.

With regard to the single-column substructure, most weight and cost all are post itself, put on power on the deck because this post has to bear all.In order to reduce the flexural stress in the post, the useless length of post need be reduced to minimum.

When first the installation (and not being fixed to the seabed as yet), have seabed stability in order to make building, a triangular base can suitably be set in the seabed, and on this pedestal, put a three-legged supporting frame.

Before this, proposed trishores tower building thing, wherein, post is to be supported by three supporting legs that are fixed on the isolation on the stratum, seabed.This building is in british patent specification 2,116, discloses in 237.Yet there is shortcoming in this structure, promptly requires post to extend to the whole height on deck from the seabed, and supporting member need be fixed on the stratum, seabed.

Usually the exploitation of hydrocarbon sub-marine field is to adopt fixing drilling well/production platform to be transported to harbour on the bank by the seabed oil inlet pipe with oil is gentle, and this platform can support and be used for handling oil or gas equipment partly, and therefore, oil or gas can be by seagoing pipelines and pump fortune.

In order to exploit at a distance less seabed oil-bearing layer because provide from storage layer position until on the bank the oil pipeline of harbour be uneconomic.Under these situations, can adopt pontoon (example: come and go tank vessel) that oil is transported to harbour.

In the time of crude oil is drawn onto in order to the pontoon that oil is transported to harbour on the bank from sub-sea drilled wells (and/or seabed oil-bearing layer) pump, a problem can take place when crossing wave influence regional in crude stream.The generation of this problem is that employed any equipment all will be subjected to because the effect of the power that wind, wave, trend and tidal effect form the pontoon owing to oil is transported to by the wave influence area from sub-sea drilled wells.

This equipment must be designed to resist " uncommon incident " that these environment stresss cause.These incidents may comprise an a-hundred-year billow and the unusual hurricane more than 12 grades.Designing a movement system of resisting these uncommon incidents is the task of a complexity, is " wind vane " or head against the wind basically because oil is transported on the bank pontoon.Therefore, on a seabed fixed point, oil must be transported by the enough firm equipment that can stand uncommon incident, and also has the ability of pontoon as " wind vane ".

The device that comprises this equipment must protect " standpipe " or many standpipes not to damage because of the collision of ship with adding.(" standpipe " this speech special implication is arranged in the industry of coastal waters and represent an oil pipe with oil from the seabed through wave influence area and sending on the sea.)

For extremely, known pontoon is used to load from large-scale loading floating drum or has compliant riser or the offshore oil of the articulated column of the feed-line of connection since then.(device that is used to load from the oil of floating drum is disclosed in patent specification U.K, 2,250,253 in).Floating drum and post were owing to the precalculated position of leaving them was damaged in the past, and the result causes the loss and the corresponding product loss of equipment.

At present proposed to make one and had the fixed tower shape building of turning, wherein, load arm is installed in the top of turning.Should fixing tower shape building must be one than load floating drum or the big member of articulated column.In order to constitute the equipment of an economy, proved the design that is simplified to fix tower shape building so that it only comprises that the necessary member of quantity minimum is feasible.

One known proposal comprises a tower shape building, and it has a central post, and three supporting legs and a usefulness piled anchor are affixed to the basal component in seabed.Supporting leg all is fixed to one in the top and puts, and central post passes cover and is fixedly connected to this and puts.Central post extends to a position (so a kind of tower shape building has been disclosed in british patent specification 2,136,860 in) on the height of the strongest wave of the uncommon incident that ad-hoc location is anticipated from the seabed.

This known suggestion has shortcoming, and promptly a standpipe is not the outside that must be fixed to central post, must walk around a small half of footpath corner at the root of central post exactly, and it could move up in the wave influence area in passing the scope of post like this.

Under first kind of situation,, standpipe will be subjected to the impact of ship if being fixed to the outside of post.Under second kind of situation, the small radius corner of oil pipe being walked around the post root makes situation more complicated.Therefore, a central post that extends downwardly into the seabed is not suitable for admitting standpipe (or J-shaped pipe).

In view of the above-mentioned defective of prior art, the object of the present invention is to provide a kind of lower support structure with marine structure of a central post, described lower support structure can keep standpipe, can resist wave and other natural force.

For achieving the above object, the invention provides a kind of lower support structure with marine structure of a central post, when this building is installed in the sea, this central post is arranged to extend vertically upward, and wherein have at least three to be used for putting the footing that comes to the seabed and at least three upwards and extend inward into the supporting leg on a top from corresponding footing, when building is installed in the sea, the supporting leg top is lower than the wave influence area, the apical support of supporting leg is on the central post intermediate point, its characteristics are, have the circumferential horizontal part that extends between adjacent legs and with the same horizontal plane of circumferential horizontal part in stretch to the radial level parts of a central point from respective leg, the bottom of central post is fixed on the described central point and prevents horizontal movement, and described central post bottom separates a big slightly distance of bend radius than standpipe or J-shaped pipe with the seabed, and between the footing of the junction of radial level parts and a supporting leg and an adjacent legs X-bracing is arranged.

Preferably, between the radial level parts connect the footing of the each point of supporting leg and adjacent legs, X-bracing is arranged all.

Preferably, each tie rod in the X-bracing between paired adjacent legs has the locational short upper arm between two long underarms that are connected to adjacent footing and two footings that are connected to supporting leg and the top, wherein, the upper end of X-bracing and the described circumferential horizontal part that between adjacent legs, extends and tie together from the described radial level parts that respective leg extends to a central point.

Preferable, when building was installed in the sea, central post extended to the position that is higher than the wave influence area.

Preferable, circumferentially be connected about midpoint with supporting leg along a leg length with the radial level parts.

Preferable, be suitable for footing being fixed to the seabed with the mode of piling.

Now example is in conjunction with the drawings described the present invention's one specific embodiment, wherein:

Fig. 1 is the lateral view of a marine carrying tower;

Fig. 2 constitutes the pedestal of bottom of this tower and the more detailed lateral view of central post;

Fig. 3 to 6 is the plan views along horizon III-VI among Fig. 2;

Fig. 7 is the lateral view of central post and pedestal, represents the standpipe relevant with post with this pedestal and the structure of J-shaped pipe;

Fig. 1 represents that one comprises the sea carrying tower of triangular base portion, and this triangular base portion has three supporting legs that support a central post, and this central post is equipped with a bearing assembly.

This marine structure has three to be used to put the footing 10 that comes on the seabed, and three from its footing upwards and extend inward into the steel tubular supporting leg 11 on a top 12.When this building is installed to the sea, for example stake 14 is squeezed into by pile protection 15, make supporting leg top 12 be lower than the wave influence area.

Now referring to Fig. 2 to 6, it has represented to be used for the detailed structure that the support of central post is provided with, and Fig. 2 is a detailed lateral view of this building.With the height in the representative of the line shown in the Roman number III to VI emersion seabed, Fig. 3 to 6 provides plan view among Fig. 2.

X-bracing (total usefulness 16 marks) is arranged on each plane that is limited by adjacent legs 11.Therefore there are three X-shapeds that directly point to the inclination on top 12 to support base plate.Each base plate has two underarms 17 that are connected on the adjacent footing 10, and with approximately be positioned at footing 10 and top 12 in the middle of supporting leg on two upper arm 18 being connected of point 19 places.Point 19 is in the same place the circumferential horizontal part 21 that extends between adjacent legs (clearly visible from Fig. 5) with the radial level parts 22 that extend to a central point (or node) 23 from each supporting leg are strained.

Parts

21 and 22 constitute the plane tie rod layer of a level.

All inclined walls (17 and 18) and horizontal part (21 and 22) are all made by the less steel pipe of diameter, and are soldered on the supporting leg 11 and suitably welded together mutually.

The sizable hollow steel column 24 of one diameter is from node 23, passes sea level 25 through top 12 and extends upward and arrive a deck support or the seat 26 of turning (it is irrelevant with turn assembly 27 1 its concrete structures and a present invention).The stage casing part of post 24 is passed the sea, so only has single post to stop the wave passage of process tower.In this case, the wave load that acts on the tower is minimum.12 post 24 is being supported on the top in the upper end of supporting leg 11, and this top 12 is positioned at half position of height between node 23 and sea level.The radial component of converging with node 23 22 makes the bottom position of post 24 exceed the long distance in seabed one.

The assembly 27 of turning is positioned at the top of seat 26 of turning, and is supporting the load arm 28 with oil pipe.During use, a reciprocating type oil groove ship (not shown) receivability is from the oil of oil pipe and be transported on the bank unloading dock.

Shown structure has special advantage, is that the X-bracing 16 of the inclination between supporting leg and horizontal tie rod 21/22 have constituted an effective support structurally that is used for post 24 lower ends.This structure does not need the post of total length (i.e. distance from the seabed to the tower), because the flexural stress in the post can act in the plane of top 12 and parts 21/22.In addition, this building need not be positioned at the plane tie rod on the stratum, seabed, and footing 10 can rely on the seabed independently like this.

Fig. 7 one corresponds essentially to the view of Fig. 2, represents that a standpipe 29 and J-shaped pipe 31 are along entering and turn over a suitable angle is positioned at the central post 24 on warp-wise parts 22 height with feeding lower end near on the height in seabed.

Suitably be arranged on the top, seabed by the lower end with post 24, standpipe and J-shaped pipe can adopt a suitable radius of curvature to arrive the seat 26 of turning directly upwards to penetrate central post inside, turn assembly 27 and load arm 28.

Claims

1. lower support structure with marine structure of a central post, when this building is installed in the sea, this central post is arranged to extend vertically upward, and wherein have at least three to be used for putting the footing that comes to the seabed and at least three upwards and extend inward into the supporting leg on a top from corresponding footing, when building is installed in the sea, the supporting leg top is lower than the wave influence area, the apical support of supporting leg is on the central post intermediate point, it is characterized in that, have the circumferential horizontal part that extends between adjacent legs and with the same horizontal plane of circumferential horizontal part in stretch to the radial level parts of a central point from respective leg, the bottom of central post is fixed on the described central point and prevents horizontal movement, and described central post bottom separates a big slightly distance of bend radius than standpipe or J-shaped pipe with the seabed, and between the footing of the junction of radial level parts and a supporting leg and an adjacent legs X-bracing is arranged.

2. lower support structure as claimed in claim 1 is characterized in that, connecting at the radial level parts between the footing of the each point of supporting leg and adjacent legs all has X-bracing.

3. lower support structure as claimed in claim 1 or 2, it is characterized in that, each tie rod in the X-bracing between paired adjacent legs has the locational short upper arm between two long underarms that are connected to adjacent footing and two footings that are connected to supporting leg and the top, wherein, the upper end of X-bracing and the described circumferential horizontal part that between adjacent legs, extends and tie together from the described radial level parts that respective leg extends to a central point.

4. lower support structure as claimed in claim 1 is characterized in that, when building was installed in the sea, described central post extended to the position that is higher than the wave influence area.

5. lower support structure as claimed in claim 4 is characterized in that, circumferentially is connected about the length midpoint along supporting leg with supporting leg with the radial level parts.

6. lower support structure as claimed in claim 1 is characterized in that described footing is suitable for being fixed to the seabed with the piling mode.

7. lower support structure as claimed in claim 3 is characterized in that, described footing is suitable for being fixed to the seabed with the piling mode.

8. as claim 4 or 5 described lower support structures, it is characterized in that described footing is suitable for being fixed to the seabed with the piling mode.