GB2359787A - Jack up platform supported on suction piles - Google Patents

Description

2359787 1 SHALLOW WATER OFFSHORE PLATFORM This invention relates to

offshore shallow water platforms, particularly intended for use in industries associated with exploration and/or production of oil, gas or other resources.

British patent No. 1 540 928 discloses a conventional offshore shallow water platform comprising a deck structure and a plurality of support legs for supporting the deck structure above sea level.

In use the platform is floated into position with it's legs in the raised position, whereupon the legs are lowered onto the seabed. The deck structure is then raised out of the water to a suitable height above sea level. Finally the deck structure is clamped firmly to the legs.

A disadvantage of the above-mentioned platform is that the seabed may be soft, comprised of weak soils, and/or uneven, thereby making it difficult to reliably install the platform.

Another disadvantage is the previous use of large structure support foundations which impose large loads on the sea bed soils due to horizontal drag loading.

We have now devised a platform and a means of installing and supporting the same, which alleviates the above problems.

According to the present invention there is provided a shallow water platform comprising a deck structure, a plurality of support legs slidably mounted to the deck structure and suction piles for securing said legs to the sea bed.

In use the platform is secured to the seabed by connection to suction piles inserted in the sea bed.

The piles can be inserted to a controllable depth facilitating installation in uneven sea bed conditions. Also, they experience far less severe drag loading than a large gravity base support, thus they impose less load on the sea bed soils and allow installation in a wide range of sea bed conditions.

Also in accordance with this invention, there is provided a method of installing a shallow water platform comprising a deck structure, a plurality of support legs slidably mounted to the deck structure and suction piles, the method comprising inserting the suction piles into the seabed, securing the platform legs to the suction piles, moving the deck structure to the desired height above the sea surface and clamping it to the legs.

A specific embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings in which:Figure 1 is a side view of a shallow water platform in accordance with this invention; Figure 2 shows a method of fixing the platform legs to the suction piles; Figure 3 illustrates the use of the platform legs to facilitate installation.

2 Referring to Figure 1, there is shown a shallow water platform comprising a deck structure 1 and a plurality of support legs 2 disposed at respective corners of the deck structure 10. The legs 2 are slidable axially of themselves relative to the deck structure 1.

The deck structure 10 and legs 2 are moved relative to each other during installation using a jacking system or strand jacks (not shown).

The lower end of each leg 2 is connected to a suction pile 3. This connection may be made prior to installation or the suction pile 3 may be installed separately and prior to the platform leg 2 connection to it.

An additional frame 4 can be used to provide extra support as required.

The suction pile 3 can be connected to the legs 2 with a rigid connection as shown in Fig 1 or can be connected with a pin-jointed connector 5 as illustrated in Fig 2.

During installation the platform legs 2 can be used to facilitate a method of attaching the hose 7 to the suction pile 3. This is shown in Fig 3. A valve 6 is provided so that the hose 7 can be connected to the suction pile 3. The hose 7 is connected through the leg 2 to the support boat (not shown), whence the suction pile 3 can be pumped out to produce suction to the seabed. This obviates the need for divers to make the connections which is an alternative if the valve 6 is placed on the outside of the suction pile 3 and not inside the leg 2.

Removal of the platform can be facilitated by simply cutting the legs 2 off at the connection point with the suction piles 3.

3

Claims (11)

1. A shallow water platform comprising a deck structure, a plurality of support legs slidably mounted to the deck structure and suction piles for securing said legs to the seabed.

A shallow water platform as claimed in Claim 1 wherein the suction piles can be inserted to a controllable depth into the seabed.

A shallow water platform substantially as herein described and illustrated in the accompanying drawings.

4. A method of installing a shallow water platform comprising a deck structure, a plurality of support legs slidably mounted to the deck structure and suction piles, the method comprising inserting the suction piles into the seabed, securing the platform legs to the suction piles, moving the deck structure to the desired height above the sea surface and clamping it to the legs.

5.

A method as claimed in Claim 4 wherein the lower end of each leg is connected to a suction pile prior to installation.

6. A method as claimed in Claim 4 wherein the suction piles are installed separately and prior to the connection of the platform legs to said suction piles.

7. A method as claimed in any of claims 4 to 6, wherein the suction piles are connected to the legs with a rigid connection.

8. A method as claimed in any of claims 4 to 6, wherein fie suction piles are connected to the legs with a pin-jointed connector.

A method as claimed in any of claims 4 to 8, wherein a hose is connected from each suction pile to a support boat, said hose being routed inside of the platform legs with a valve placed inside each leg to allow hose connection and pumping out of each suction pile.

10. A method as claimed in Claim 9 wherein the valves and the hoses are placed on the outside of the suction piles.

11. A method of installing a shallow water platfonn, the method being substantially as herein described and illustrated in the accompanying drawings.