RU2499098C2 - Ice-resistant self-lifting platform for freezing shallow water and method of its installation - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: platform comprises a support base made in the form of a bottom board with a developed surface, strongly connected with a perpendicularly installed ice-resistant support block, somewhat protruding towards the bottom below the level of the near-bottom plane of the board. At the same time the ice-resistant support block is made in the form of a cylindrical column; special pipes - water-separating columns installed into the ice-resistant support block, through which operating wells are drilled; a superstructure made in the form of three replaceable floating decks with U-shaped cuts in the centre: decks of civil construction purpose, decks of drilling purpose and decks of operational purpose, at the same time U-shaped cuts are made as congruent to the cross section of the ice-resistant support block; detachable lifting mechanisms installed on the outer side along the perimeter of the U-shaped cut of the deck, engagement or disengagement with the support base is provided, as well as movement and fixation of the deck at the safe height of the ice-resistant support block; piles for fixation of the support base drilled with a drilling plant along a curvilinear trajectory provide for safe operation of the structure.

EFFECT: increased reliability of operation and process safety of an area of water during civil construction and drilling works.

3 cl, 3 dwg

Description

The invention relates to the hydraulic engineering construction of structures, in particular, to ice-resistant self-lifting platforms for the development of freezing shallow water for a long time, for example, such as the water area of the Ob-Taz Bay:

Known ice-resistant floating offshore platform for oil and gas production (RF patent 67542 according to class B63V 35/44 from 2007) containing a surface upper structure mounted on a vertically located support semi-immersed in water with tension supports for fixing the platform in a given place. The support base, in turn, consists of two sections in height, a lower section, which is completely located under water, and an upper section, on which the upper structure rests. The disadvantage of this structure is the impossibility of its use in shallow water with weak bottom soils at depths of 1 to 4 meters.

A known installation and method for providing drilling platforms on the high seas, comprising a support structure (support base) and a tender barge (floating deck) (RF patent 2139220 according to class B63B 35/44, E02B 17/02 of 1999), which after Analysis adopted as a prototype. The disadvantage of the prototype is the impossibility of its use in harsh climatic conditions of the Arctic.

The technical result of the claimed ice-resistant self-elevating platform for freezing shallow water, and especially on soft soils, as well as the method of their installation with subsequent operation, is: - acceleration of field commissioning by ensuring year-round use of the platform in arctic conditions; - improving the reliability of operation and technological safety during the construction, installation and drilling operations, as well as during the operation and maintenance of wells and technological equipment by reducing ice loads due to the creation of a single support base; - simplification of installation work during the construction of the structure on soft soils of shallow water at sea depths of 1 to 4 meters due to preliminary ballasting of the bottom plate with its subsequent fixing with piles of a curved profile; - ensuring the reuse of two decks (construction and drilling) for the development of the following promising fields in this oil and gas bearing area.

This technical result is achieved in an ice-resistant self-elevating platform for freezing shallow water in that: an ice-resistant self-elevating platform for freezing shallow water, including a support base made in the form of a ballastable floating bottom with a developed plate surface, firmly connected to a perpendicularly mounted ice-resistant support block made in the form of an ice-resistant a cylindrical column, slightly protruding toward the bottom below the level of the bottom plane of the plate to create tightness inside the column, in which special pipes (water separating columns) are installed, designed for drilling operations, while the upper structure is made in the form of three with U-shaped in the center cutouts of removable floating decks: construction, drilling, and operational purposes, while U- the shaped cutouts of all decks are congruent to the cross section of the ice-resistant support block, while the lifting mechanisms installed on the deck along the perimeter of the cutout are designed for docking and undocking the deck and the support block , and to raise the deck to a safe height from the waves with its subsequent fixation; moreover, these mechanisms can be removed for the period of use of this deck, and then re-installed to organize the descent of the deck into open water.

The specified technical result is also achieved by the fact that in the ice-resistant self-lifting platform for freezing shallow water, each removable deck is equipped with its own buoyancy, taking into account the technological equipment installed on it, and is also adapted for transportation with a tugboat, while preventing deck distortions relative to horizontal provisions are provided; ballast sectionalized tanks / pont located around the entire perimeter of each deck tones whose filling regulates the balance.

The indicated technical result is also achieved by the fact that in the method of sequentially mounting removable decks in the first navigation period, an ice-resistant self-lifting platform is towed to the drilling point equipped with the first removable deck for construction purposes, then the support base is lowered using lifting mechanisms while filling ballast of the bottom plate, providing preliminary fixing of the platform on the seabed, and final fixing of the platform on the ground they are carried out using a special drilling rig adapted for drilling piles along a curved path, then special pipes, the so-called water separating columns, through which the required number of production wells are drilled, are installed in the ice-resistant support block, and the second deck of the drilling rig is towed to the drilling point in the second navigation period destination, launch the first deck, after which it is diverted away from the ice-resistant support block from the U-shaped cut with tugboat and then using the same tugboat in place of the first deck set the second deck and raise the second deck to a predetermined height and fix it, then start drilling production wells, while the first deck is towed to the dock for repair and reception of the next ice-resistant foundation, and the third navigation period to the drilling point is towed by the third operational deck, which is similarly installed and used until the end of field development, and the second deck is similarly returned I am at the dock to perform subsequent functional tasks.

The proposed technical solution is illustrated by drawings, where: in Fig.1 shows a General view of an ice-resistant self-lifting platform for freezing shallow water; figure 2 shows a section aa of figure 1 of a self-lifting platform; figure 3 shows the towing to the drilling point during the navigation period of the ice-resistant self-lifting platform with the first removable deck fixed in the lower position.

1 - ice-resistant self-lifting platform (LSPP) for freezing shallow water; 2-foot base;

3 - removable floating deck with a U-shaped center neck;

4 - ice-resistant support block (LOB);

5 - bottom ballasted plate;

6 - special pipes (water separating columns);

7 - U-shaped neckline;

8 - wellhead;

9 - sea muddy bottom;

10 - piles;

11 - ice field;

12 - lifting mechanisms.

13 - oil rig

Ice-resistant self-lifting platform (LSPP) 1 (Fig.1-2) for freezing shallow water, consists of a support base 2 and the upper structure, made in the form of removable floating decks 3 with a U-shaped center cutout 7. Support base 2, in turn , made in the form of an ice-resistant support block (LOB) 4 with an extensive bottom ballasting plate 5, additionally fixed by curved piles.

LSPP 1 has three removable decks: a deck for construction purposes, a deck for drilling purposes and a deck for operational purposes.

All removable floating decks 3, in order to be able to get in close contact with the support block 4 installed on the seabed 9 or to leave it after the completed functional task, have a U-shaped cutout 7. Cutout 7 is made congruent to the cross section of the forehead 4 of the form.

Each removable floating deck 3 has its own buoyancy, taking into account the technological equipment installed on it, which is suitable for the functional purpose and is adapted for transportation by tug.

Lifting mechanisms 12 are installed along the perimeter of the U-shaped cutout from the side of the deck, thanks to which all interchangeable decks 3 can be joined or disengaged from the support base 2, and also can be moved and fixed at the required height. The mechanisms 12 must be removable and removed after each operation of raising / lowering the deck to accommodate other equipment.

The bottom plate 5 with a developed surface is a ballast tank, firmly connected to the perpendicularly mounted LOB 4, slightly protruding to the bottom below the bottom plane of the plate / tank. The developed surface ("vastness") of the bottom plate 5 prevents overturning from ice slide and is most rational for laying on muddy soils of the seabed. The ice-resistant support block 4 is made in the form of a cylindrical column with a cross-sectional diameter of 15-20 m. For the estimated number of wells (including backup), special pipes 6 (water separating columns) are installed in LOB 4 through which the entire drilling process is carried out; the distances between the axes of the planned production wells 8 on the forehead are taken at least 3 m. The implementation of the support block 4 with specialized pipes 6 provides the platform with additional strength and resistance to resistance to ice loads. The cross section of LOB 4 is designed to accommodate up to 12 deviated and horizontally directed wells in order to maximize drainage coverage of the reservoir / field. The total height of the supporting base 2 as a dock product depends on the depth of the sea at the installation point, taking into account the necessary (safe) clearance. LOB 4 and ballast bottom plate 5 are fastened using a special drilling rig adapted to drill piles 10 along a curved path in order to significantly increase the stability of monopod-type platforms under ice impacts characterized by overturning forces (sliders). And since the movement of the ice fields 11 is distinguished by a variety of directions depending on factors such as winds and currents, piling should be carried out along differently directed paths in order to increase the resistance of the LOB 4 to the shear and tipping forces of the moving ice fields 11 and hummocks.

Field development begins with towing in the navigation period to the drilling point of an ice-resistant self-lifting platform with a construction and assembly deck (see Fig. 3). At the drilling point, with the help of lifting mechanisms 12, the supporting base 2 is lowered to the bottom, being filled with ballast, and upon reaching the bottom, deck 3 begins to rise above sea level to the required height, while the bottom ballasted slab is further deepened into the ground, thereby preliminary fixing of the platform.

The first removable deck during the first inter-navigation period carries out work on the reliable fastening of the support base 2 on the seabed 9. The support base 2 is fastened using a special drilling rig adapted to drill piles along a curved path. Next, special pipes 6 are installed in the ice-resistant support block 4, through which the drilling process is carried out.

Further, having ascertained in the process of the first ice drift that the LOB 4 is reliable in resisting ice influences, the second deck (drilling destination) is towed to the drilling point in the second navigation period. In parallel with this, launching is carried out using the already known lifting mechanisms 12 of the first deck. Having reached the sea, the lifting mechanisms 12 of the first deck 3 weaken the engagement, allowing it to be moved away from the forehead 4 from the U-shaped cutout 7 using a tug. Then, with the help of a tugboat, the second deck is joined to the place of the first deck with a U-shaped cut to LOB 4, then the second deck is lifted using the same lifting mechanisms to a given height with its subsequent fixation. After that, the first deck is transported by the same tug to the destination (port / dock) for possible repair and reuse.

After changing the decks, drilling begins during the second inter-navigation period (moreover, if the drilling process exceeds the estimated number of wells, then drilling will continue into the third inter-navigation cycle).

Upon completion of drilling during the navigation period, the next deck change occurs in a similar way, i.e. the second deck (for drilling purposes) is replaced by a third deck (for operational purposes), which, after lifting and fixing on the forehead, will already be at sea until the end of the development of the field.

Thus, for the implementation of the above solution, when replacing decks again, it is necessary to use only one towing vessel, since all the above decks are not self-propelled in order to reduce their weight; however, all deck replacement operations must be performed during the navigation period. The proposed technical solution is most acceptable in undeveloped areas with necessary infrastructure, freezing for a long time and having a very short navigation period (40-50 days).

Claims (3)

1. An ice-resistant self-elevating platform for freezing shallow water, including a support base made in the form of a ballastable floating bottom with a developed plate surface, firmly connected to a perpendicularly mounted ice-resistant support block, made in the form of an ice-resistant cylindrical column, slightly protruding to the bottom below the level of the bottom plane of the plate to create tightness inside this column, in which special pipes are installed - water separating columns designed for drilling operations d, while the upper structure is made in the form of three with U-shaped cutouts in the center of removable floating decks: for construction, drilling and operational purposes, with the U-shaped cutouts of all decks made congruent to the cross section of the ice-resistant support block, and the lifting mechanisms installed on the deck along the perimeter of the cut-out, they are designed both for docking and undocking the deck and the support block, and for raising the deck to a wave-safe height with its subsequent fixation, and these mechanisms, in order to save space spares can be removed for the period of functional use of each particular deck, and then re-installed to organize the launching of the deck in open water. 2. An ice-resistant self-elevating platform for freezing shallow water according to claim 1, characterized in that each interchangeable floating deck has its own buoyancy, taking into account the technological equipment installed on it, and is adapted for transportation using one tug, and the horizontal position of the decks, based on centrally located support block; ballasting sectionalized containers / pontoons provided around the entire outer perimeter support. 3. The method of sequential installation of removable decks of an ice-resistant self-elevating platform for freezing shallow water, which consists in the fact that in the first navigation period an ice-resistant self-elevating platform is towed to the drilling point equipped with the first removable deck for construction purposes, then the descent is carried out using the lifting mechanisms support base with simultaneous ballast filling of the bottom plate, providing preliminary fixing of the platform on the seabed, and final mounting the platform on the ground is performed using a special rig adapted to drill a curved path along the pile, then placed in ice-resistant support block special pipes, so-called risers through which drilling is performed the required number of wells; in the second navigation period, the second drilling deck is towed to the drilling point, the first deck is launched, then it is diverted away from the ice-resistant support block from the U-shaped cutout using a tugboat, and then using the same tugboat to the place of the first deck establish the second deck and raise the second deck to a predetermined height and fix it, then start drilling production wells, and the first deck is towed to the dock for repair and receiving another ice-resistant foundation; in the third navigation period, the third operational deck is towed to the drilling point, which is similarly installed and used until the end of field development.

Images