JPH0542521B2 - - Google Patents

Description

[Detailed description of the invention] ≪Industrial application field≫ This invention is applicable to gravity-type underwater structures, such as petroleum and
The present invention relates to refloating devices and methods, such as gas production platforms.

<<Prior art>> Gravity-type underwater structures, such as oil and gas production platforms, have an underwater structure fixed to the bottom of the water, and compared to floating or jacket-type platforms, they have a lower payload and lower weight. It has various advantages, including a large oil storage capacity, stable operation under harsh natural environmental conditions, and the ability to ease oil loading restrictions on shipping tankers.

<<Problems to be solved by the invention>> With this type of gravity platform, there was no consideration at all of relocating and reusing it in the event that oil and gas fields were depleted in the future.
Therefore, platforms installed on oil and gas fields with short life cycles are not necessarily more cost-effective than floating or jacketed platforms.

This invention enables underwater structures, such as gravity oil and gas production planets, to be refloated, relocated, and reused, thereby:
The purpose is to significantly improve the superiority of gravity-type underwater structures.

≪Means for Solving the Problems≫ In order to achieve the above object, the present invention provides a method for embedding a plurality of pipes in the frame of an underwater structure such as a platform, and connecting the open end of each pipe to the underwater structure. The device invention is characterized in that the device is arranged on the bottom plate, its periphery, and the inner circumference skirt, and each pipe is connected to a pump that supplies high-pressure water and/or high-pressure gas. A jet of high-pressure water and/or high-pressure gas is ejected from the periphery of the submerged structure, and the jet removes the earth and sand from the periphery of the bottom plate and the lower surface of the underwater structure, and separates the grout between the bottom plate and the submerged ground. A feature of the method invention is that refloating is achieved by generating an appropriate amount of buoyancy.

<<Example>> Hereinafter, an example of the present invention will be described in detail using the drawings.

FIG. 1 is an elevational view showing the overall configuration of a gravity-type oil and gas production platform, which is an underwater structure to which the present invention is applied, and FIG. 2 is a sectional view of the main parts.

The platform 10 of this embodiment includes an underwater structure 14 fixed to the underwater ground E via grout 12, a support 16 extending above the water from the top of the underwater structure 14, and a support above the water surface WL of the support 16. It is provided with a deck 18 fixed to the upper end protruding from the top.

On deck 18 is tank 2 for well drilling, oil extraction, and gas extraction.
0 and a building 22 constituting a control room, living room, etc., and various equipment such as processing equipment such as oil/gas separators, pumps, etc. are installed as necessary.

The underwater structure 14 has a partition wall 32 in an airtight space closed by an outer wall 26, a top plate 28, and a bottom plate 30.
partition into multiple vertically and horizontally, partition wall 32
Oil and gas are stored in each room divided by , and these oil and gas are transferred to the outside through a pipeline 24 connected to one side of the underwater structure 14 .

Further, an outer circumferential skirt portion 34 is provided on the outer circumferential bottom surface of the bottom plate 30, and an inner circumferential skirt portion 36 is provided protrudingly provided on the inner circumferential side, and these skirt portions 34 and 36 are dug into the underwater ground E.

Outer wall 2 of underwater structure 14 configured as above
6 and the partition wall 32, a plurality of supply pipes 38 for supplying high-pressure water and/or high-pressure gas are embedded as shown in FIG. Each tube 3
The distal end openings 40 of 8 are respectively connected to the outer skirt portion 3.
4, the lower surface of the bottom plate 30, and the inner and outer circumferences of the inner skirt portion 36.

The other end of each pipe 38 is collected at the upper part of the underwater structure 14 and connected to high-pressure water (not shown) provided on the deck 18 through the inner peripheral part of the support column 16.
Or connected to a pump for high pressure gas supply.

Then, by spouting high-pressure water or pressure gas through each pipe 38, the underwater ground E is excavated by the jet stream, and the underwater ground E is
and the underwater structure 14 can be separated from each other.

Next, a method of re-floating the platform 10 fixed to the underwater ground using the above flotation device will be explained with reference to FIG.

First, as shown in a, after removing the turret 20, the building 22, and other equipment mounted on the deck 18, and removing the pipeline 24, the ballast water stored in the underwater structure 14 is pumped to a drainage pump. It is discharged by P1, and the entire weight of the platform 10 and the acting buoyancy are almost balanced.

Next, as shown in b, the supply pump P2 installed on the deck 18 is operated to jet high pressure water or high pressure gas from the pipe 38.

This operation is performed in the order shown in FIG.

That is, initially, the underwater structure 14 was
This is done by jetting high-pressure water or pressurized air from the outer periphery of the outer skirt side 34 through a pipe 38 installed on the outermost periphery of the submersible structure 14, thereby disturbing and digging up the earth and sand around the periphery of the underwater structure 14. As a result, the frictional force between the outer circumferential skirt portion 34 and the underwater ground E is removed.

Next, as shown in FIG.
A water channel is formed through the lower end of the bottom plate 30 , and it becomes possible to discharge the earth and sand accumulated under the bottom plate 30 to the outer periphery of the underwater structure 14 .

Next, the ground below the grout 12 is disturbed by jetting out the portion shown in , and the adhesion force to the bottom plate 30 is removed.

After this, the grout 12 attached to the bottom plate 30 is removed by jetting the part shown in
is crushed and peeled off. Furthermore, the ground around the inner peripheral skirt portion 36 can also be disturbed.

Thereafter, the disturbance of the ground below the grout 12 located inside the inner circumferential skirt portion 36 and the friction between the inner circumferential skirt portion 36 and the water bottom ground E are removed by jetting out the portion shown in FIG.

Finally, the grout 12 adhered to the inner circumference of the bottom plate by blowing out the partial jet shown in
can be crushed and peeled off.

In this way, by sequentially supplying high-pressure water or high-pressure gas from the outer periphery to the inner periphery of the bottom of the underwater structure 14, the bottom of the underwater structure 14 is separated from the underwater ground E. In addition, the above
The order of If the ejection work is performed, the underwater structure 14 will be completely separated from the underwater ground E.

In this state, as shown in FIG. 3c, the structural part 1
While draining the palast water accumulated inside 4,
By supplying pressurized air to the inner periphery of the skirt portions 34 and 36 through each tube 38, the buoyancy increases accordingly, and the planet form 10 begins to gently re-float.

Thereafter, the trim of the platform in the water can be maintained by supplying and draining ballast water into each compartment by operating the drainage pump P1, and the platform can be towed to another installation location by a tugboat or the like.

In addition, a plug may be interposed in the tip opening 40 of each tube 38 to prevent seawater or grout from entering.

<<Effects of the Invention>> As explained in detail in the embodiments above, in this invention, with the above configuration, the gravity type underwater structure can be re-floated and relocated, so that the advantages of the gravity type underwater structure can be enjoyed. However, by making it possible to reuse the product, economic advantages can also be secured.

[Brief explanation of the drawing]

Fig. 1 is an elevational view of the gravity platform according to the present invention, Fig. 2 is a sectional view of the main parts showing the underwater structure of the platform, and Fig. 3 a, b, and c are the same planet form. FIG. 10... Gravity platform, 12... Grout, 14... Underwater structure, 30... Bottom plate, 3
8... Supply pipe, 40... Opening, P2... Supply pump.

Claims (1)

[Claims] 1. A plurality of pipes are buried in the frame of an underwater structure such as a platform, and the open end of each pipe is arranged on the bottom plate of the underwater structure, its periphery, and the inner circumferential skirt. A gravity-type underwater structure refloating device, characterized in that each pipe is connected to a pump that supplies high-pressure water and/or high-pressure gas. 2 High-pressure water and/or high-pressure gas is jetted out from the bottom plate and its periphery of the underwater structure that has landed on the bottom of the water, and the jet jet removes the earth and sand from the bottom plate periphery and the lower surface of the underwater structure, and the bottom plate is connected to the bottom of the water. A method for re-floating a gravity-type underwater structure, which is characterized by peeling off the grout in between and re-floating the underwater structure by generating an appropriate amount of buoyancy. 3. The method for refloating a gravity-type underwater structure according to claim 2, wherein the jet is ejected sequentially from the periphery toward the center of the underwater structure.