RU2591110C1 - Sea floating process platform for drilling and/or production and storage in ice conditions - Google Patents

Abstract

FIELD: shipbuilding.

SUBSTANCE: invention can be used in designing structures to be used in freezing seas. Offshore floating platform for drilling and/or producing and storing in ice conditions comprises outer side of hull including at least two additional symmetric sections. First section is located on the upper section and has the shape of polygonal regular prism or cylinder with outer diameter not more than 0.9 of section diameter on which it is located. Second additional section is located within the section of hull outer side upper section with back taper, which is made with double knuckle in the form of two consecutive cone-shaped sections with reverse located along the platform axis. Upper section has angle of inclination of horizon about 30 degrees, and lower - nearly 50 degrees. Total height of section with double knuckle is not less than rated ice thickness in water area of the corresponding platform operation area.

EFFECT: possibility to reduce impact of ice loads on platform and improved navigability.

4 cl, 2 dwg

Description

The invention relates to the field of shipbuilding, and more specifically to the shape of the hull of floating platforms for various purposes, and can be used in the design of such structures for use in freezing seas.

Known technical solutions (RF patent No. 2502629 dated 12/09/2010 “Floating platform and a method for controlling it”) for an offshore floating ice-resistant platform for drilling and / or production and storage, which includes a housing with side walls symmetrical with respect to the central vertical axis of the platform and closed from below bottom. On the deck there is technological equipment for various purposes. The outer side walls of the hull consist of at least three sections counted from the upper end: a water level section, the diameter of which decreases in the downward direction along the central axis and within which during operation of the platform in ice conditions there should be a sea water level, the middle section is cylindrical the shape and lower section, the diameter of which increases in the downward direction along the central axis. The draft of the platform is much smaller than its diameter, and the center of buoyancy of the platform for the submerged part is below the center of gravity of the platform. On the bottom of the platform there is a removable element for connecting and directing anchor lines, risers and cables.

However, in winter conditions, the platform is subject to significant loads from interaction with ice formations. In addition, in conditions of significant sea disturbance, the platform experiences rolling, which negatively affects the operation of technological equipment and habitat conditions. There is a need for further improvement of the known platform in terms of changing the shape of the hull for equally efficient operation in difficult natural conditions, both in ice periods and in periods of clean water without stopping the working processes occurring on the platform, according to its main purpose.

The objective of the invention is to reduce the load from the impact of ice fields on the offshore floating platform, as well as improving the seaworthiness of the platform by reducing the pitching in conditions of significant sea waves.

For this, an offshore floating platform for drilling and / or production and storage in ice conditions, having a hull with side walls symmetrical with respect to the central vertical axis of the platform and closed from below, the outer side of the hull comprising at least three sections counted from above, the upper of which has the shape of an inverted cone or a multifaceted pyramid with a height within which the sea water level should be located during operation, the middle section is in the form of a cylinder or a multifaceted regular of the prisms and the lower section has the shape of a cone or a multifaceted pyramid, and the platform sediment is much smaller than the diameter of the upper conical shape of the section at the water level, and a removable element is attached to the bottom of the platform for connecting anchor lines, risers and cables to the body, according to the invention a symmetrical outer side of the platform body made with additional at least two symmetric sections, the first of which is located on the upper section, in the form of an inverted polyhedral pyramid or cone, has the form of many rannoy regular prism or a cylinder with an outer diameter of not more than 0.9 times the diameter of the section on which it is placed, and providing a result of the formation of the annular horizontal area around said additional cylindrical section on said upper surface of the base section. The second additional section is located within the section of the upper section of the outer side of the hull with reverse taper, which as a result has a double scraper in the form of two consecutive conical sections with reverse taper, successively following one another along the platform axis, the upper of which has an angle of inclination of the generatrix to the horizon of about 30 degrees and within which during operation should be the level of sea water, and the lower of them - about 50 degrees. Moreover, the total height of the indicated section with a double break is not less than the estimated ice thickness in the water area of the corresponding platform operating area. The lower conical section of the outer side of the platform body has a diameter of at least 1.1 times the diameter of the middle cylindrical section of the outer side of the platform body.

In addition, the additional cylindrical section of the platform may have a reverse taper portion in its upper part.

In this case, the base of the upper conical section of the outer side of the platform body, on which the additional cylindrical section of the platform is located, can be equipped with a cylindrical insert.

Along with this, the offshore platform can be equipped with a propulsion-steering complex based on helical-steering columns.

By supplementing the outer side of the platform body with a symmetrical section shaped as a regular polyhedral prism or cylinder located on the upper section, having the shape of an inverted polyhedral pyramid or cone, and an outer diameter smaller than the diameter of the base of the section on which it is placed, an annular horizontal platform is formed around the indicated an additional cylindrical section on the base surface of said conical section. The presence of this site favorably affects the reduction in pitching due to effective damping due to the partial entry of this site into the water during waves.

The lower cone-shaped section of the outer side of the platform, which has a larger diameter with respect to the middle cylindrical part of the hull, also has a beneficial effect on the reduction of pitching, especially vertical, due to the involvement of additional attached masses of water. In addition, it also reduces the possibility of broken ice falling under the bottom of the platform, reducing unwanted force on the anchor lines and risers of the platform.

The introduction of an additional section located within the section of the upper section of the outer side of the hull with reverse taper, which as a result has a double scrapping in the form of two cone-shaped sections with reverse taper consecutively following each other along the platform axis, favorably affects the platform's resistance to ice loads. So, the upper cone-shaped section of the indicated fracture, having an angle of inclination of the generatrix to the horizon of about 30 degrees, implements the main type of ice destruction upon contact with the surface of the platform body - breaking due to bending of the ice cover down due to the conical shape of the body, with the formation of a system of radial and circumferential cracks. The purpose of the cone-shaped section with an inclination angle of the generatrix of about 50 degrees, located below the fracture is to reduce the value of the ice load component associated with turning and pushing fragments of ice formations during the transition from the cone-shaped surface with an inclination angle of the generatrix of about 30 degrees to the middle cylindrical surface of the platform body.

The essence of the invention is illustrated by drawings, where in FIG. 1 shows an offshore platform for drilling and / or production and storage in ice conditions; FIG. 2 shows an offshore platform of FIG. 1 with additional sections and propulsion system, where:

1 - additional cylindrical section;

2 - upper section;

3 - annular horizontal platform;

4 - additional section;

5 - middle section;

6 - lower section;

7 - bottom;

8 - removable element;

9 - anchor lines;

10 - risers;

11 - section with reverse taper;

12 - upper deck;

13 - cylindrical insert;

14 - propulsion and steering complex;

15 - technological and / or drilling equipment.

The proposed offshore platform for drilling and / or production and storage in ice conditions has a housing consisting of round sections of various configurations in plan (Fig. 1). The housing has side walls symmetrical with respect to the central vertical axis of the platform. The additional cylindrical section 1 (Fig. 1) has the shape of a multifaceted regular prism or cylinder with an outer diameter smaller than the diameter of the base of the conical section 2. The diameter of section 1 is not more than 0.9 of the diameter of the base of the conical section 2. The difference in diameters ensures the formation of an annular horizontal platform 3 , which on a wave is partially immersed in water and involves additional attached masses. The upper section 2 has the shape of an inverted polyhedral pyramid or cone, the angle of inclination of the generatrix to the horizon is about 30 degrees. During operation in ice conditions, the level of sea water is located within the section. Down along the vertical axis there is a similar additional section 4, which also has the shape of an inverted cone or a polyhedral pyramid with an angle of inclination of the generatrix to the horizon of about 50 degrees. The double scrap formed by sections 2 and 4 is designed to reduce ice loads associated with turning and pushing fragments of ice formations along the platform. The total height of the specified section with a double break is not less than the estimated thickness of the ice in the area of operation of the platform. The middle section 5 has the shape of a cylinder or a multifaceted regular prism, and the lower section 6 has the shape of a cone or a multifaceted pyramid. At the same time, the lower section 6 has a diameter of at least 1.1 the diameter of the middle section 5 and is closed from the bottom by a bottom 7. In the bottom of the platform 7 there is a removable element 8 for connecting the platform with anchor lines 9 of the containment system and risers 10.

In addition, the marine floating platform on the additional cylindrical section 1 (Fig. 2) of the platform may have a section with inverse taper 11, the presence of which allows to reduce the fillability of the upper deck 12 of the platform.

Also for such a platform, on the basis of the upper section 2 (Fig. 2) of the outer side of the hull, a cylindrical insert 13 can be located. This allows for ease of installation of the hull set, which will reduce the complexity of assembly work during the construction of the platform.

The platform can be equipped with a propulsion and steering complex 14 (Fig. 2) in the form of helical columns in an amount that ensures its movement at the required speed.

The platform is operated in waters with a constant or partial presence of ice. On the flat upper deck 12 (Fig. 2), according to the main purpose of the platform, there is technological and / or drilling equipment 15. The hull of the platform held on anchor lines 9 is subject to stresses and ice formations. In the ice-free period, the water level is at the level of the upper section 2. With significant sea waves, the annular horizontal platform 3 between sections 1 and 2 is partially immersed in sea water and due to this the angular pitch amplitudes decrease. Due to the presence of the inverse taper section 11, which acts as a wave deflector, the fillability of the upper deck 12 is reduced. During operation of the platform in ice conditions, the water level is also located within the upper section 2. When ice formations collide with the upper section 2 of the platform, ice breaks account of its bending downward. After that, the fragments of ice formations fall on an additional section 4 located between the upper section 2 and the middle section 5, where they unfold and push along the platform body, as a result of which ice loads on its body are reduced. Fragments of ice formations falling on the lower section 6 are diverted to one side, thereby preventing them from falling under the bottom of the platform 7 and damage to anchor lines 9 and risers 10 is eliminated. In the event of a chance of collision with critical ice formations, the platform is disconnected from the removable element 8 (Fig. 2) and due to the operation of the propulsion and steering complex 14, the platform moves to a safe distance from the point of operation. After the departure of critical ice formations, the platform returns to the point of operation and its work resumes.

The proposed offshore floating platform for drilling and / or production and storage in ice conditions reduces ice loads on it, and in conditions of significant sea waves, it has improved seaworthiness due to a decrease in the pitching amplitudes. In this connection, it can be operated both in periods of clean water and in ice conditions, which compares it favorably with the prototype.

Claims (4)

1. A marine floating platform for drilling and / or production and storage in ice conditions, having a hull with side walls symmetrical with respect to the central vertical axis of the platform and closed from below, the outer side of the hull comprising at least three sections counted from the upper end, one of which has the shape of an inverted cone or a multifaceted pyramid with a height within which during operation in ice conditions the level of sea water should be located, the middle section is in the form of a cylinder or a multifaceted of the correct prism, and the lower section has the shape of a cone or a multifaceted pyramid, and the draft of the platform is much smaller than the diameter of the upper section of the conical shape at the water level, and on the bottom of the platform there is a removable element for connecting and directing anchor lines, chains, risers and cables, characterized in that the symmetrical outer side of the platform body is made with additional at least two symmetric sections, the first of which is located on the upper section, in the form of an inverted polyhedral pyramid whether the cone is in the form of a multifaceted regular prism or cylinder with an outer diameter smaller than the diameter of the base of the section on which it is placed, amounting to not more than 0.9 of its diameter and resulting in the formation of an annular horizontal platform around the specified additional cylindrical section on the base surface of the aforementioned upper sections, the second additional section is located within the section of the upper section of the outer side of the hull with reverse taper, which as a result has a double scrap in e two consecutive conical sections with inverse taper successively following each other along the platform axis, the upper of which has an angle of inclination of the generatrix to the horizon of about 30 degrees and within which during operation there should be a sea water level, and the lower of them - about 50 degrees, moreover, the total height of the specified area with a double break is not less than the estimated thickness of the ice in the water area of the corresponding operating area of the platform, while the lower cone-shaped section of the outer side of the hull latformy has a diameter of at least 1.1 times the average diameter of the cylindrical section of the outer hull side platform. 2. The marine floating platform according to claim 1, characterized in that the additional cylindrical section of the platform may have in its upper part a section with reverse taper. 3. The marine floating platform according to claim 1, characterized in that the base of the upper conical section of the outer side of the platform body, on which the additional cylindrical section of the platform is located, can be equipped with a cylindrical insert. 4. The marine floating platform according to claim 1, characterized in that it can be equipped with a propulsion and steering complex in the form of helm columns.

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