A device for temporarily holding an offshore drilling rig in the arctic shelf


E02D23/16 - Jointing caissons to the foundation soil, specially to uneven foundation soil

 

(57) Abstract:

Usage: in hydraulic engineering, in particular, can be used in the construction of offshore drilling on the Arctic shelf. The inventive device for temporarily holding an offshore drilling rig in the Arctic in terms of the progress of the ice fields in the reference column placed piles. Each pile on the internal surfaces are made with hollow ribs, a portion of which is bypassed refrigerant, others lose fluid, and third - flush fluid. 1 C.p. f-crystals, 8 ill.

The invention relates to hydraulic structures (artificial Islands), mainly to exploration and production offshore drilling units (MBU). With the greatest effect, it can be applied in the Arctic waters, which regularly operate heavy ice fields.

In the world practice for many years we are searching for such structures MBU, who could resist the advances of the ice fields without interrupting the operational mode. Created, for example, reinforced concrete substructure MBU in the form of a truncated cone, so that when nadhani ledang the Ktsia in PCT patent N 86/06771 class. E 02 In 17/02, from 1986 or U.S. patent N 3952527, CL E 02 In 17/00, 1977.

The disadvantage of such constructions is mainly their high cost of manufacture, since the construction of these enormous structures in Arctic conditions is very difficult.

Also long ago developed the idea of a more simple design substructures, which would have a relatively low own weight, but nevertheless could withstand shear effort of moving ice field. For this purpose the lower part of the support base is supplied hammered into the bottom of the pile. For example, we can refer to such structures sea platforms for U.S. patent N 3811289, CL E 02 In 17/00 from 1974 or N 4784526, CL E 02 In 17/00, from 1988, Japan's bid N 58-19806, CL E 02 In 17/00, 1983, etc. In most cases hammered into the soil pile (often concrete) almost become sacrificial, as in the transition MBU at another point the waters of the said piles practically be extracted from the bottom is either not possible, or necessary for this complex (expensive) devices. In addition, the extraction of such piles from the ground takes a lot of time.

In recent years considered is the creation of ice pillows.

In the United States developed a technical solution (U.S. patent N 4187039, CL E 02 In 17/00 from 1980) to create an artificial ice island. To do this, using underwater caissons to form an annular volume of water within which washes the walls of the caissons outside freeze-known holoprotein equipment placed inside the mentioned caissons and formed their volume. The so formed frozen soil under the caissons increases the stability of the MBU.

This known technical solution, obviously, can significantly improve the resistance MBU shift under the action of the ice fields, but there is a significant disadvantage from the point of view of manufacturing technology and production of structural elements. The fact that under the technical solution required to produce and deliver in Arctic waters special caissons. They should be equipped not only separate, stand-alone refrigeration units, and systems of immersion (ascent) with remote control authorities. Thus, the expected effect of unreasonably roads in achievement.

Known technical solution for and.with. USSR N 1168665 Μl. E 02 In 17/02 from 1985 (prototype) concerning oporn the boron pipe sections, tightly connected to each other. Each section is provided with a heat exchanger (cooling unit), placed inside the partition.

After you push the columns in the ground floor is the frosting around the mentioned sections of ice coats. At the same time is frozen and in contact with the sections of the soil, which leads to increased coupling sections with the ground.

What is the main drawback of this seemingly very promising design. The fact that such a construction of the support columns is not acceptable in Arctic conditions, as it is not protected from the effects of a moving ice field.

The objective of the invention is to provide such a construction of the supporting base MBU for a temporary hold on the Arctic shelf, which will be obtained reliably withstand the impact of a moving ice field; the maximum possible reduction of cost to manufacture the necessary supporting elements of design and their application in the process of setting MBU at the point of drilling and removing it for driving to another area and it's all due to the overlapping functions of the elements of the substructure, which in its composition it is necessary only to Podgornoe the basis of an offshore drilling unit (MBU) is made in the form of underwater Mat with at least one hollow support column, for example, a cylindrical shape, within which is placed movably piles with the opportunity to interact with the implementation mechanism at the top and a guiding device at the bottom, with each pile along its inner surface provided with hollow ribs, hydraulically connected with the reservoir for supplying fluid to the working environment.

The problem is solved in that the first part of hollow ribs are made of a perforated and through its collector connected to the washing liquid.

The problem is solved in that the second part of the ribs through its collector connected to the system coolant supply and the third part of them is connected via its collector to the system to lose fluid.

The problem is solved by the fact that all piles are placed equidistant from each other on the inner forming surface of the supporting columns.

The problem is solved in that the pile is provided with a nozzle for supplying it with compressed air and a discharge pipe pulp connected with the discharge pipe. The lower end of which is placed in the area of the collectors.

In Fig. 1 gives a General view of the base of an offshore drilling rig; n section b-B of Fig. 3; Fig. 5 section b-b of Fig. 3; Fig. 6 type G Fig. 4; Fig. 7 type D Fig. 4; Fig. 8 - section E-E of Fig. 3.

Support Foundation MBU contains installed on mate 1 columns 2, 3, along the inner surface of which is placed piles 4. Each pile along its inner surface provided with hollow ribs 5, 6, 7, United (grillage) corresponding collectors 8, 9, 10 with the pipes 11, 12, 13 of the supply of working fluid agents. Hollow ribs 6 (for feeding washing liquid) is made with the holes 14 of the perforation, and the ribs 7 are summed up and the washing liquid through the pipe 12. The pipe 13 to the inlet and outlet of the refrigerant to the ribs 5 is protected by a casing 15. All internal casing surface protected with insulating material 16.

At the top of the piles installed pipes: 17 for supplying coolant 18

to supply wash water, 19 compressed air 20 from the discharge pipe 21 for removal of eroded soil. Piles pass through the routing device 22.

To perform technological operations on development of certain waters of the Arctic basin on the bottom ground is established by known means Mat 1 (typically the structure MBU with technological equipment. The upper structure of this sentence is not the subject of the invention is widely and therefore not shown.

Consider the technology of production of Mat 1 with the supporting column 2. It is hollow, mostly cylindrical design, through the Central part of which is held drilling tool (not shown). On the inner surface of the column 2 equidistant placed in the guiding device 22 is introduced into the soil ternoway 4. For the introduction of these piles, there are several types of mechanisms. This can be pile driving equipment or device for the push in the form of a rack-pinion mechanism or system traverse driven by hydraulic mechanisms. In this case, the device for the introduction of the 4 piles in the soil does not affect the subject matter of the invention and therefore not described in detail.

For the implementation of the next pile, it is introduced in a known manner in interaction with the injection mechanism (push) and immersed in the soil. Upon reaching the design elevation of the injection mechanism is released from the pile and set on the following. At the end of the staging pile them perform operation on podsoednineny device ternoway 4 is so at the lowest cost in the manufacture of scarce metals its shell to get the maximum effect in operation. It is often necessary to ensure the strength of the metal replaced less scarce ribs that run in the form of semi-cylinders 5, 6, 7, welded to the inner surface of the piles 4 increments determined by calculation. In this part of the ribs, for example, 5 are designed for coolant supply part 6 for ozonation of water forming a slurry, and part 7 for the fluid.

Work on introduction of piles is that when its gradual entry into the ground in the area of the face is served washing fluid through the manifold 9 and the corresponding ribs 7. To the resulting slurry would be more thin, through the manifold 10 and the ribs 6 may be served water through the holes 14. As further implementation of the 4 piles into the ground pulp is accumulated, rises up and spills out through the pipe 20. Depending on the properties of the soil may be that the water for ozonation is not required, then the corresponding collector and ribs may be idle.

After the implementation of all 4 piles into the ground at the corresponding edges of jesenia resistance in the event of an impending ice fields.

This increase resistance base from moving and tear-loads due to the following factors. As is known, the size of the columns in the cross-section of a few meters. Depth push the pile into the ground is more than 10 meters Distance between the piles OK. 1.0 m Thus, it is easy to imagine a lot of frozen soil, which prevents crowding of the platform under the action of the pressure of ice at the expense of the said mass of frozen soil. In addition, the area of frozen ground in the vertical plane is hundreds of square meters, which naturally prevents shifting efforts from the action of the ice field.

To increase the bearing capacity (resistance to shear loads) certain plays an important role guiding device 22. It consists of a ring (see Fig. 8) with cells for passage of piles 4. Freezing of the soil and the pulp is slightly above the location of the sending device 22. In this case, the soil (pulp), frozen within 4 piles, and outside, becomes a monolith in the case of advances of the ice field shifting efforts from the piles 4 are transferred to the column 2 through n is of metal.

For improving the operational efficiency of the system plays an important role in the removal of the pulp. The fact that the freezing of the entire column of slurry to the nozzle 20 is unprofitable due to the high cost of the refrigerant. Therefore, optimally, when the above guide device 22, the pulp will be removed. To do this, through pipe 19 (after the end of the process of freezing piles up to and slightly above the fixture 22) is supplied with compressed air. Through the discharge pipe 21 and the pipe 20 in the compressed air, the pulp is completely removed, and the air is a good insulator, preventing the buildup of ice pillows above the guide device 22.

Upon completion of technical operations at this point the waters, if necessary, driving MBU on the flow of the refrigerant is stopped. On these same channels can be skipped another working fluid agent with a high temperature (heated water, air, exhaust gases from the running engines, etc.,) In the layer of contact between pile and soil liquefies and facilitates the removal of the pile from the ground.

The inner surface of the casing 15 is covered with the insulating material 16, which prevents the freezing of nahodyaschiysya production (lifting) at the point of drilling, successfully resists the movement of the ice field and reduces the cost of manufacture of individual elements of the structure.

And the placement of piles 4 on the inner perimeter columns 2, 3 allows you to get a ring of frozen soil, which increases the weight attached to the ground, the cross-sectional area formed ring at a much lower cost cold than when fully frozen mentioned volume of soil.

1. A device for temporarily holding an offshore drilling rig in the Arctic shelf, containing the supporting base with support columns with piles, interacting with implementation mechanism, characterized in that each pile along its inner surface is made with hollow ribs, part of which is made of a perforated and through its collector connected to the washing liquid, the hollow part of the ribs is connected through its collector to the supply system refrigerant, and the remainder of these ribs through its collector to the system to lose fluid, each pile is provided with a nozzle for supplying it with compressed air and a discharge pipe pulp connected with the discharge pipe, the lower end of which RA is the column along its perimeter and equidistant from each other.

 

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