KR100452595B1 - Method for Installation of an Offshore Platforms on a Substructure Without the Impact and the Load Concentration - Google Patents

Abstract

The present invention aims to prevent the impact load occurring between the legs of the deck and the pile of the jacket at the beginning of the load transfer and to prevent the load from being excessively concentrated on one of the various connections during the load transfer process.

For this purpose, in the present invention, the bridge of the offshore platform deck connected to the pile of the jacket, which is a lower support structure, is composed of a hydraulic cylinder. Before ballasting cargo barges to increase draft, open the hydraulic valves to lower the hydraulic cylinders on the deck legs and connect them to the jacket pile without impact. The hydraulic cylinders, which are the legs of the deck, move freely up and down before the hydraulic valves are locked, so there is no impact when they are connected.

Description

Method for Installation of an Offshore Platforms on a Substructure Without the Impact and the Load Concentration}

The present invention is a technique belonging to IPC E04 B 1/35, which is a method of installing and fixing the deck of the offshore platform on the lower support structure at sea.

The offshore platform consists of a steel structure "jacket" and a "deck" mounted on it, and is used for the drilling and production of oil and gas. There are several ways to install a deck over the jacket, which is the lower support structure at sea. Up to now, the installation of the deck of the offshore platform has been generally divided into the structure of the deck divided into parts, each part is lifted down by the crane ship, and assembled in the sea. Such methods are well known but limited by the capacity of available crane vessels and the like, are very time consuming and require expensive costs.

Recently, the integrated deck approach has been introduced as another way to install decks on offshore platforms over jackets. Installation after completion of a single structure on land, rather than multiple sector structures, greatly reduces installation time and costs, and uses common cargo barges, not crane barges. Since the integral deck has a considerable weight, it cannot be lifted by crane barges and transported to deck where cargo barges are located, then ballasted cargo barges and increased draft are seated on the jacket, the lower supporting structure.

However, this method is sensitive to wind, tide and waves because the deck is on the cargo barge during installation.

When the cargo barge increases in motion depending on the sea condition, a large collision load is generated between the bridge of the deck and the pile of the jacket, which is the ballasting of the cargo barge and at the beginning of the load transfer. Due to the considerable weight of the deck, the impact load at this time may also be excessive, resulting in a severe deformation of the connection between the deck leg and the pile of the jacket, making the connection difficult.

In addition, after some degree of ballasting of cargo barges and sufficient contact between the deck legs and the piles of the jacket, the movement of cargo barges increases according to the sea conditions, causing the load to be excessively concentrated in one of several connections. do.

The present invention aims to prevent the impact load occurring between the legs of the deck and the pile of the jacket at the beginning of the load transfer and to prevent the load from being excessively concentrated on one of the various connections during the load transfer process.

For this purpose, in the present invention, the bridge of the offshore platform deck connected to the pile of the jacket, which is a lower support structure, is composed of a hydraulic cylinder. Before ballasting cargo barges to increase draft, open the hydraulic valves to lower the hydraulic cylinders on the deck legs and connect them to the jacket pile without impact. The hydraulic cylinders, which are the legs of the deck, move freely up and down before the hydraulic valves are locked, so there is no impact when they are connected.

When the cargo barge reaches the highest level during the vertical movement, the speed is momentarily lost, so closing the hydraulic valve at this time can complete the connection without impact. The hydraulic valve is configured as a one-way valve that allows fluid flow into the hydraulic cylinder even when locked, allowing the hydraulic cylinder to be lowered further when the highest level is reached.

Even if the deck legs and the jacket pile are connected without impact, excessive load rotation of the cargo barge will concentrate the load on one of the connections. Too much concentrated load can cause serious damage to the structure. To prevent this, connect the hydraulic cylinders that make up the legs of the deck with hydraulic pipes so that the load is equally distributed. Since the loads applied to the respective connecting portions are not excessively distributed, it is possible to alleviate the structural design conditions of the legs and the jacket of the deck and the hydraulic cylinder. The hydraulic cylinders connected also allow the cargo barge to be free to rotate without concentrating loads on each connection.

Installing and removing the hydraulic cylinders inside the deck bridge of the offshore platform is not an easy task. If the hydraulic efficiency needs to be improved, the hydraulic cylinders are divided and installed outside the deck legs. The hydraulic cylinders or the hydraulic cables are also connected between the divided hydraulic cylinders. If the deck of the offshore platform is huge, considerable load will be applied to the hydraulic cylinders that make up the legs of the deck, so the cross section of the piston in the hydraulic cylinder should be secured enough. The required cross-sectional area can also be secured.

1 is a front view of a state where a cargo barge is placed on the lower support structure for installing a deck of a marine platform;

2 is a detailed view illustrating the connected hydraulic cylinder supporting the deck of the offshore platform;

3 is a front view of the lowered hydraulic cylinder connected to mount the deck of the offshore platform onto the lower support structure;

4 is a front view of a state in which the cargo barge freely moves up and down before locking the hydraulic valve.

5 is a front view of a state where the hydraulic valve is locked at the highest water level during the vertical movement of the cargo barge.

6 and 7 are front views showing the rotational movement in the state of closing the hydraulic valve of the cargo barge

8 is a structural diagram when the hydraulic cylinder is dividedly installed outside the deck

<Description of the symbols for the main parts of the drawings>

(1) offshore platform

(2) cargo barge

(3) jacket, which is a submarine supporting structure

(4) deck bridge of offshore platform

(5) bottom connection of deck legs

(6) top connection of jacket file

(7) Jacket pile as vertical member of lower supporting structure

(8) Deck support structures on cargo barges

(9) mooring and panthering system

(10) Hydraulic cylinder to support the deck legs

(11) hydraulic piston

(12) Hydraulic fluid

(13) hydraulic valve

(14) Hydraulic fluid storage and control device

(15) hydraulic pipe or hydraulic cable

The cargo barge 2 carrying the deck of the finished offshore platform 1 is located above the lower support structure jacket 3 as shown in the front view of FIG. 1 and the lower connection 5 of the deck leg and the upper connection 6 of the jacket pile. Prepare to connect. At this time, the cargo barge 2 maintains a fixed position through the mooring and the panda system (9).

As shown in FIG. 2, the deck leg 4 of the offshore platform is composed of a hydraulic cylinder 10, and as shown in FIG. 3, the hydraulic valve 13 is opened and the fluid 12 is injected from the hydraulic control device 14. Lower (10). At this time, the cargo barge 2 has not yet started ballasting. When the hydraulic cylinder 10 constituting the deck leg 4 is sufficiently lowered, the bottom connecting portion 5 of the deck leg and the upper connecting portion 6 of the jacket pile come into contact with each other.

In the state as shown in FIG. 4, since the hydraulic valve 13 is open and the fluid 12 is freely moved into the hydraulic cylinder 10, the hydraulic cylinder 10 also lowers and raises as the cargo barge 2 moves up and down. do.

As shown in FIG. 5, when the cargo barge 2 reaches the highest level during the vertical movement, the hydraulic valve 13 is locked. The instantaneous speed when the cargo barge 2 is at the highest water level during the up and down movement becomes "0" so that the bottom connection 5 of the deck leg and the top connection 6 of the jacket pile are connected without impact.

Even after closing the hydraulic valve 13, if a higher maximum water level occurs, the fluid 12 further flows into the hydraulic cylinder 10 and the hydraulic cylinder 10 expands. The hydraulic valve 13 is configured as a one-way valve that allows the inflow of the fluid 12 into the hydraulic cylinder 10 even when locked so that the hydraulic cylinder 10 is additionally provided when the cargo barge 2 reaches the highest level higher than before. Allow you to descend.

Even if the lower connection part 5 of the deck leg and the upper connection part 6 of the jacket pile are connected without impact, when the cargo barge 2 rotates, the load is concentrated to one of the connection parts 5 and 6. do. In order to prevent this, as shown in FIGS. 6 and 7, the hydraulic cylinders 10 constituting the deck legs 4 are connected by hydraulic pipes or hydraulic cables 15. Through the hydraulic pipe or hydraulic cable 15, the loads acting on the respective connecting portions are equally distributed and allow the rotational movement of the cargo barge 2. Since the loads applied to the respective connecting portions 5 and 6 are not excessive, the structural design conditions of the deck legs 4, the hydraulic cylinder 10, the jacket pile 7, and the connecting portions 5 and 6 are alleviated. You can do it.

Thereafter, ballasting the cargo barge (2) and increase the draft to transfer the deck load of the offshore platform (1) to the lower support structure of the jacket (3) to complete the installation.

Installing and removing the hydraulic cylinder 10 inside the deck bridge 4 of the offshore platform is not an easy task. Therefore, when it is necessary to increase the work efficiency, the inflow cylinder 10 outside the deck bridge 4 as shown in FIG. Install separately. Each of these divided hydraulic cylinders 10 is also connected via a hydraulic pipe or hydraulic cable 15. In the case where the deck of the offshore platform 1 is huge, a considerable load also acts on the hydraulic cylinder 10 constituting the deck leg 4, so that the cross-sectional area of the piston 11 in the hydraulic cylinder 10 must be sufficiently secured. Dividing the hydraulic cylinder 10 to the outside of the deck leg 4 to install a number of it can also secure the required cross-sectional area.

(Variations, applications and legal interpretations)

The present invention is not limited to the specific preferred embodiments described above, and various modifications can be made by those skilled in the art without departing from the gist of the invention as claimed in the claims. Of course, such changes are intended to fall within the scope of the claims.

The present invention prevents impact loads occurring between the lower connection of the deck leg and the upper connection of the jacket pile at the time of connection via the connected hydraulic cylinder and at the beginning of the load transfer.

By connecting each hydraulic cylinder with a hydraulic pipe or hydraulic cable, the rotational movement of the cargo barge prevents excessive concentration of load on one part of the connection.

In addition, by dividing the hydraulic cylinder to the outside of the deck leg as necessary, it is easy to install and remove, it is possible to secure the cross-sectional area of the piston in the required hydraulic cylinder.

Claims (4)

In mounting a marine platform on a cargo barge and then installing it on a jacket, an offshore supporting structure, Hydraulic cylinders are installed in connection with the deck legs, and the respective hydraulic cylinders are connected by hydraulic pipes or hydraulic cables, and the lower connections of the deck legs and the upper connections of the jacket pile are installed without impact loads and concentrated loads. Method of installing the offshore platform without impact and concentrated load on the offshore substructure. The method of claim 1, A method of installing an offshore platform without impact and concentrated load on an undersea structure, comprising a method of dividing and mounting a hydraulic cylinder on the outside of a deck leg. The method of claim 1, A method of installing an offshore platform without impact and concentrated load on an offshore undercarriage comprising mounting a hydraulic cylinder on a jacket pile rather than a deck bridge. Mount the offshore platform (1) on top of the cargo barge (2) where the fixed position is maintained, eg through mooring and panthering systems (9), and then place the cargo barge (2) on the jacket (3), which is the lower support structure. And lowering the hydraulic cylinder 10 connected to the deck leg 4 so that the lower connecting portion 5 of the deck leg contacts the upper connecting portion 6 of the jacket pile, and the water level of the cargo barge 2 Locking the hydraulic valve 13 when the maximum is reached and the instantaneous speed is "0", connecting the lower connection 5 of the deck leg to the upper connection 6 of the jacket pile without impact, and the cargo barge 2 The hydraulic cylinder 10 is further lowered by the one-way valve when the water level is higher than the conventional level, and the load of the offshore platform is increased by increasing the draft by ballasting the cargo barge 2. 3) so that the steps to complete the installation A method of mounting a marine platform on a cargo barge through a marine undersupport structure, the method comprising: The hydraulic cylinder 10 is connected to the hydraulic pipe 10 or the hydraulic cable 15 so that the load is not distributed by the rotational movement of the cargo barge 2 on the connecting portions 5 and 6 so that the load is distributed equally. A method of installing an offshore platform without impact and concentrated loads on an offshore undercarriage, characterized in that it is included.