WO2010015046A1

WO2010015046A1 - Flexible device for connection of a pipe to an offshore floating production unit, between two segments of pipes, and between a pipe and a subsea equipment

Info

Publication number: WO2010015046A1
Application number: PCT/BR2008/000368
Authority: WO
Inventors: Petrucio Benoni Orlanti; Fernando Guilherme Castanheira Kaster
Original assignee: Petrucio Benoni Orlanti; Fernando Guilherme Castanheira Kaster
Priority date: 2008-08-06
Filing date: 2008-12-04
Publication date: 2010-02-11
Also published as: BRMU8803199U2

Abstract

The request of invention patent for 'flexible device for connection of a pipe to an offshore floating production unit, between two segments of pipes, and between a pipe and a subsea equipment' aims a simple solution to increase the pipes service life, diminishing the fatigue at a critical region of its.structure, caused by natural.or non-natural agents, and to absorb all angular movements of the pipe, so as to eliminate the combined efforts of bending and tension on the pipes. The device is constituted of five main elements: two pipe spools (2) with two opposing structural arms (5) and an pad eye (6) at each arm end; two structural rings (9, 10) with four holes in 90 degrees phase and one flexible pipe segment (4). The assembling of the five elements is done by the connection of the arms of both pipe spools (2) to the structural rings (9, 10) through shafts (11); and once the flexible pipe segment is positioned on the flexible device center line, has its ends connected to the pipe spools by screws.

Description

FLEXIBLE DEVICE FOR CONNECTION OF A PIPE TO AN OFFSHORE FLOATING PRODUCTION UNIT, BETWEEN TWO SEGMENTS OF PIPES, AND BETWEEN A PIPE AND A SUBSEA EQUIPMENT.

Invention patent of a "flexible device for connection of a pipe to an offshore floating production unit, between two segments of pipes, and between a pipe and a subsea equipment". This patent was created to solve the chronic problem of pipes due to its connection between subsea equipment, such as oil wells, manifolds, etc and many types of vessels and floating production platforms. Offshore oil production has demanded a wide use of floating production platforms. The hull of such units can be of various types: such as semi- submersible platforms; floating, production, storage and offloading vessels (FPSO); floating, storage and offloading vessels (FSO); tension leg platforms; spar buoys; calm buoys, and others. Floating production platforms are generally fixed at the sea bottom through several anchor lines; the quantity and the size of which depend on several issues, like size of the unit, water depth, meteoceanographic conditions at the site of installation, etc. It is important to point out that some projects of production units can, though not so frequently, present a positioning system based on self propulsion known as dynamic positioning system. Once the floating production units are positioned at the surface of the sea, there is the need that the oil coming from the productions wells, located at the sea bottom, reach the units in order to be processed in an existing plant and/or stored. After that, oil processed and/or stored in the floating unit, and the gas resulting from this processing, will need to be transferred onshore via pipe lines or tankers.

On both flowing forms presented, i.e., oil from production wells reaching floating unit or being pumped out of it, the use of pipes is necessary. As a result, these pipes must be permanently connected to their respective floating units, as long as they are on operation, so as to maintain the operational continuity. There are several materials used to make these pipes; steel or a combination of steel and high resistance synthetic fiber respectively known as pipe steel or flexible pipe. However fabrication in other materials is also possible. Once the floating production units or platform are anchored, with their production or offloading pipes connected, they will be vulnerable to local metocean conditions. Such situation will cause movements of the floating unit on the sea level, due to the influence of winds, current and waves. Consequently, such movements of the unit will be transmitted to all elements hanging up on it, including production and/or offloading pipes. The connection between pipes and their respective production units may present damages or rupture problems, generally due to fatigue caused by the relative and frequent movement between the two systems, i.e., the platform and the pipes that come from the sea bottom.

Together with the fatigue problem of the pipes, there is also the fact that they are submitted to high tension, when floating production units are installed in deep water. Such tension is directly related to the weight of the hanging segment of pipe, that is, the segment between the sea bottom and the sea level.

This scenario shows that there is a tension combined with a bending load on the pipes where they are connected to the platform. Alone, tension loads do not cause great structural problems on the pipes, but together with bending efforts, they are highly destructive. So, that specific operational problem may occur on floating production units, or on any floating hull, that has pipes connected on it. It means that after some time, can occurs partial or total rupture of the pipes where they are connected to the platform. That means the replacement of the damaged pipes with huge oil losses besides with the costs involved in pipes repair. There are also the ceasing profits caused by the loss of oil production during the replacement period and the environmental pollution created by the leakage of oil.

The segment of hanging pipe between the sea bottom and the floating unit is also called riser by the technical community of oil industry; whereas the pipe segment laid down on the sea bottom is called flow line.

The present request of invention patent refers to a "flexible device for connection of a pipe to an offshore floating production unit, between two segments of pipes, and between a pipe and a subsea equipment" has a main function of eliminate the bending efforts on a certain area of the pipes; such area can be located at the pipe end, close to the floating unit or any place along the pipe line.

The device object of requesting present invention was designed to permit the connection of the upper end of the pipes with the floating unit; to permit the flow of fluids in and/or out of the floating unit through such pipes, without cause bending efforts at the area of connection with the floating unit; to facilitate the connection of its upper end to the existing pipe on the platform; to connect several segments of pipes present in the offloading oil line and to connect a pipe to a subsea equipment.

The production platforms or any other floating system of production need production and/or offloading pipes connected to them, so as to guarantee the continuous flow of products, like oil, gas and water. Looking for solving the problem of pipes connected to floating offshore units, devices were created with the objective of decoupling combined efforts of tension and bending at the area where the pipe is connected on the unit, or simply to increase the stiffness of the pipe at the referred area. One of the solutions currently in use is the employment of stiffener on the upper end of the pipe proposed for increase its bending resistance on the region connected to the platform. Such stiffener, which is a jacket with a cone trunk shape, can be made of metallic alloys or plastic material, for use respectively on steel pipes and flexible pipes. The second solution in use, according to Patent EP 1559941 A1 , refers to a chamber in a toroid shape, with an internal support of elastomeric material to sustain the pipe and, simultaneously, to allow its articulation inside the chamber. The articulation system of the present invention differs from that due to use of a flex and pivoted joint, preferably made of steel, instead of a pipe supported by a system of elastomeric material.

There are reports referring that both alternatives currently in use have already presented structural problems in one of its components, due to the rupture of the elastomer inside the toroid ring chamber, for the first option, and the unfastening or even rupture of the stiffener, for the second one. Among the mentioned problems, those solutions have also high costs. It is known that when such problems of failure occur, the consequences are environmental accidents due to the leaking of greasy products or gas, and repair or replacement of the damaged pipes, together with the ceasing profit of the production unit. The two solutions here described are the ones in current use in a still limited universe of employment. So, some proposals were offered, in a wish to solve the problem, according to the patents that will be commented next. The Patent US 747.411 (Pl 8602868, in Brazil) shows a universal joint surrounded by several articulated flow pipes. The conception described here does not seem to attend the problem of the pipes, since they contain several articulated points.

The Patent Pl 0400422-1 refers to a mooring line supporting some weight of the riser. That means the mooring line is connected between the structure of the platform and a riser area next to the sea level. The objective is to eliminate part of the efforts on the riser, at the place where it is connected to the platform. However, at the riser connection area of the mooring line there will be combined efforts of tension and bending which make vulnerable the structure of the riser, among that the efforts between the riser connection area and the platform will not be totally eliminated. The Patent Pl 9605 669-OA describes a mechanism where a stiffener is installed in the riser structure area close to the sea level. In this system, guide pipes are used to avoid movements of the risers and their contact with the platform structure, as well as the stiffener connection on the guide pipe base. On the other hand this system is characterized by the solution mentioned before, that means try to eliminate the efforts on the riser structure through the stiffener use, which still brings the problems of eventual failure or unfastening of the stiffener. The system described on the Patent Pl 0505400-1 A shows an articulated base covering the upper end of the riser. This conception will not reduce the difficulties related to bending and fatigue on the riser structure, because its upper end are connected in a rigid pipe on the floating unit or platform. It is also known that damage or rupture of the pipes demand repairs that request the use of vessels that are specialized in lay down operations related to rigid and flexible pipes. Such vessels have reels and/or baskets for pipe storage, devices for tension, and other special mechanisms needed for pipes lay down and repair operations. Handling long pipe segments that mean their loading, transport and installation will demand the use of pipe lay vessels. Nevertheless, such vessels are not always available on the market when there is an urgent demand for them. The merit of the invention patent request of a "flexible device for connection of a pipe to an offshore floating production unit, between two segments of pipes, and between a pipe and a subsea equipment" is to permit a simple solution to increase pipe life, reducing fatigue at a critical region of its structure, caused by natural or non-natural agents, and to absorb all angle movements of the pipe, so as to eliminate combined bending and tension efforts on it. The patent request "flexible device for connection of a pipe to an offshore floating production unit, between two segments of pipes, and between a pipe and a subsea equipment" is constituted of five main elements: two pipe spools with two opposing structural arms and an pad eye at each arm end; two structural rings with four holes in 90 degrees phase and one flexible pipe segment. The assembling of the five elements is done by the connection of the arms of both pipe spools to the structural rings through shafts; and once the flexible pipe segment is positioned on the center line of the system, has its ends connected to the pipe spools by screws. The final assembling shows a universal joint with a flexible pipe segment on the invention center line. The flexible pipe segment of the invention should be sized basically for pressure, bending, temperature and chemical composition of the product flow, since the combined efforts of bending and tension will be captured by the universal joint structure. The flanged ends of the flexible device, which are the object of the invention, will permit and facilitate connections on it. According to what was previously mentioned, the application of the present flexible device include all types of pipe, and the positioning of the invention can be in any end of the pipe to solve fatigue problems due to bending and tension loads. In such a way, one of the possible places for installation of the flexible device is a floating unit structure so that the pipe can be connected below that. Other possibility for installation of the invention is on the hanging pipe segment, at the region next to its contact with the sea bottom, contact point known as touch down point. At that place, fatigue problems due to strong bending of the pipe are also observed.

Another possible place for installation of the invention is between a subsea equipment based on the sea bottom, such as the oil collector of several production wells known as manifold, and a pipe. • The request for an invention of a "flexible device for connection of a pipe to an offshore floating production unit, between two segments of pipes, and between a pipe and a subsea equipment" may be better understood with the illustrations shown next, with the drawings that are part of this descriptive report. However, it is worth mentioning that due to illustrations of the invention are been done by drawings, they can not be considered limiting, since the invention can receive other constructive details to attend its aim. Figure 1 - Isometric View.

1 - Flexible device for connection of a pipe to an offshore floating production unit, between two segments of pipes, and between a pipe and a subsea equipment.

Figure 2 - Exploded Isometric View.

2 - Pipe spool with flanged ends, to be connected to the platform or pipe.

3 - Cylindric protuberance.

4 - Flexible pipe segment. 5 - Equal structural arms, attached and installed diametrally opposite in relation to the pipe spool 2 center line. 6 - Pad eyes.

7 - Pipe spool with flanged ends, to be connected to the pipe or subsea equipment.

8 - Equal structural arms, attached and installed diametrally opposite in relation to the pipe spool 7 center line.

9 - External structural ring with four holes in 90 degrees phase.

10 - Internal structural ring with four holes in 90 degrees phase.

11 - Four shafts, having head at one end and thread on the other, in order to connect the structural arms (5 and 8) through its pad eyes 6 to the holes of the structural ring (9 and 10), so as to permit the arms to articulate orthogonally between them.

12 - Four hexagonal nut, to be connected at each shafts 11 ends.

Figure 3 - Illustrative side view of a type of the flexible device connection on the platform hull, with detail. 1 - Flexible device for connection of a pipe to an offshore floating production unit, between two segments of pipes, and between a pipe and a subsea equipment.

13 - Floating platform.

14 - Pipe. 15 - Point of pipe contact with the sea bottom or touch down point.

16 - Sea bottom.

Figure 4 - Illustrative side view showing the connection between the flexible device and two segments of pipe.

13 - Floating platform.

14 - Pipe.

15 - Point of pipe contact with the sea bottom or touch down point. 16 - Sea bottom.

Figure 5 - Illustrative side view showing the connection between the flexible device and a subsea equipment type manifold.

1 - Flexible device for connection of a pipe to an offshore floating production unit, between two segments of pipes, and between a pipe and a subsea equipment. 13 - Floating platform. 14 - Pipe. 16 - Sea bottom.

17 - Submerged buoy.

18 - Subsea equipment type oil collector of several production wells known as manifold.

Claims

What is claimed is:

1 - Invention Patent of a "flexible device for connection of a pipe to an offshore floating production unit, between two segments of pipes, and between a pipe and a subsea equipment" characterized by increasing the pipes service life, diminishing fatigue and eliminating bending and tension combined efforts on pipes.

2 - Invention Patent of a "flexible device for connection of a pipe to an offshore floating production unit, between two segments of pipes, and between a pipe and a subsea equipment", as claimed in claim 1 , characterized by a pipe spool 2 with flanged ends, to be connected to the floating unit structure or pipe and to the flexible pipe segment 4; such pipe spool has a section with a cylindric protuberance 3, which can also be a cone trunk, so as to permit the fixation and sustaining of the flexible device on the floating unit hull. 3 - Invention Patent of a "flexible device for connection of a pipe to an offshore floating production unit, between two segments of pipes, and between a pipe and a subsea equipment", as claimed in claim 1 , characterized by a pipe spool 7 with flanged ends, to be connected to the pipes 14 or subsea equipment 18 and to a flexible pipe segment 4. 4 - Invention Patent of a "flexible device for connection of a pipe to an offshore floating production unit, between two segments of pipes, and between a pipe and a subsea equipment", as claimed in claim 1 , characterized by a flexible pipe segment 4, with flanged ends, positioned at the center line of the invention to be connected to the pipe spools 2 and 7. 5 - Invention Patent of a "flexible device for connection of a pipe to an offshore floating production unit, between two sectors of pipes, and between a pipe and a subsea equipment", as claimed in claim 1, characterized by two equal structural arms 5, attached and installed diametrally opposite in relation to the pipe spool 2 and also for each arm 5 has an pad eye 6 at its end, being the pad eyes equal.

6 - Invention Patent of a "flexible device for connection of a pipe to an offshore floating production unit, between two segments of pipes, and between a pipe and a subsea equipment", as claimed in claim 1 , characterized by two equal structural arms 8, attached and installed diametrally opposite in relation to the pipe spool 7 and also for each arm 8 has an pad eye 6 at its end, being the pad eyes equal.

7 - Invention Patent of a "flexible device for connection of a pipe to an offshore floating production unit, between two segments of pipes, and between a pipe and a subsea equipment", as claimed in claim 1 , characterized by an external structural ring 9 with four holes in 90 degrees phase, the holes have the same diameter of the structural arms (5 and 8) pad eyes and the external structural ring 9 has an octhogonal shape.

8 - Invention Patent of a "flexible device for connection of a pipe to an offshore floating production unit, between two segments of pipes, and between a pipe and a subsea equipment", as claimed in claim 1 , characterized by an internal structural ring (10) with four holes in 90 degrees phase, the holes have the same diameter of the structural arms (5 and 8) pad eyes and the internal structural ring 10 has octhogonal shape.

9 - Invention Patent of a "flexible device for connection of a pipe to an offshore floating production unit, between two segments of pipes, and between a pipe and a subsea equipment", as claimed in claim 1 , characterized by four shafts 11 to connect the structural arms (5 and 8) through its pad eyes (6) to the holes of the structural ring (9 and 10) in order to permit the arms articulate orthogonally between them. Each shaft has a head at one end and threads in the other to permit the installation of a hexagonal nut 12 on it to avoid the shafts 11 unfasten from the flexible device during the operation.