ES2729828T3 - A hybrid lifting system - Google Patents

Abstract

A hybrid elevator system (10) for the connection between a floating unit (12) and an underwater unit (14) that is located at the sea floor (18), the system comprises: a flexible composite conduit (22) for transporting a fluid between said floating unit (12) and the underwater unit (14) whereby said composite conduit comprises a joined pipe having an inner lining (30); an end pipe section (20) connected to the composite conduit, said end pipe section (20) being adapted to connect between the floating unit (12) and the composite conduit; and an additional end pipe section (24) connected to the composite conduit, said end pipe section (24) adapting to connect between the underwater unit (14) and the composite conduit (22), whereby said sections (20 , 24) end pipe comprises an unbound flexible metal pipe, the unbound flexible metal pipe comprising a plurality of metal layers, which are not bonded together and that move independently of each other, and wherein the elevator system It is adapted to assume a compatible flexible configuration when installed.

Description

DESCRIPTION

A hybrid lifting system

Technical field

The present invention relates to a hybrid lifting system for the connection between a floating unit, such as a floating vessel or a production unit for oil and gas production, and an underwater unit, such as an underwater well installation, located at the bottom of the sea. The term "elevator system" is intended to mean a pipe or chain adapted for the transport of fluids, that is, liquids and gases or mixtures thereof, and in particular hydrocarbons, such as oil and / or gas or injection fluids, such as methanol or water, between floating and underwater units.

Background of the invention

Lifting systems include a conduit through which various fluids are transported from an underwater installation located on the seabed to a floating platform or vessel on the sea surface, such as a facility for surface production and / or storage, or vice versa . The boat or floating platform is constantly exposed to movements, caused for example by waves, winds and surface and underwater currents. Therefore, the floating platform is continually subject to the forces that cause it and the lifting system is connected to the same movements. Lifting systems must be able to withstand the forces exerted on them without failing due to fatigue or the like. If part of an elevator is fatigued or damaged to the point of failure or possible failure, at least part of the elevator system must be replaced, which is expensive and can be difficult and time consuming. When lightweight, for example composite, lifting pipe is used, an additional weight added to the top of the lift that is connected to the floating platform or vessel may be required to ensure that the pipe is in tension, however, this additional weight compresses the elevator, negatively affects the flow of fluids through the elevator system and increases manufacturing and installation costs.

US Patent No. 5,639,187 discloses a marine lift system that combines rigid steel catenary elevators with flexible flow lines. The expression "catenary" refers to the curve assumed by a cord of uniform density and cross-section that is perfectly flexible but cannot be stretched and hangs freely from two fixed points. Steel catenary elevators curl upwards through the water in a smooth catenary path to a large submerged buoy which, in turn, is anchored to the bottom of the sea by clamping lines of the tension legs at a depth below the water turbulence zone. The buoy keeps the rigid steel catenary elevators in a substantially vertical position in the water. The flexible flow lines (commonly called bumps) are fluidly connected to the steel catenary elevators in the buoy and extend upward through the turbulence zone towards the surface.

A disadvantage with such a system is that a large buoy and fastening means are needed to support heavy steel elevators. Mooring the buoy to a predetermined depth also requires careful planning and engineering, which makes the design and manufacture of the buoy complex, time-consuming and expensive. In addition, the equipment required to anchor the buoy further increases manufacturing and installation costs.

US Patent No. 6,364,022 B1 discloses a hybrid deep water pipe comprising a rigid metal central part.

Summary of the Invention

An object of the present invention is to provide a hybrid lifting system for the connection between a floating unit and an underwater unit that is located on the seabed, which can withstand or accommodate the forces exerted on it due to movements, such as those caused by the movement of the floating unit.

This object is achieved by an elevator system that includes a flexible composite conduit for transporting a fluid, that is, liquid or gas, between said floating and underwater units. The term "composite conduit" refers to a bonded pipe having an inner lining and an outer protective covering and, optionally, at least one reinforcing layer, such as that described in international application WO 99/67561. WO 99/67561 describes a flexible elevator comprising composite material. The elevator comprises an inner shell of thermoplastic material, a multi-layer intermediate reinforced polymer component and an outer thermoplastic coating. The inner lining continuously joins the multi-layered intermediate component, which in turn continuously joins the outer lining. The lifting system of the invention also comprises at least one end pipe section that is adapted to connect between the floating unit and / or the underwater unit and the composite conduit. Said at least one end pipe section comprises a metal pipe, that is, a pipe made of metal or containing it, or a non-joined flexible pipe. The elevator system is adapted to assume a compatible flexible configuration when installed.

The term "unbound" is intended to mean a pipe consisting of a plurality of layers, which comprise a metal or polymer, for example, that are not bonded together and therefore are free to move independently of each other. An unbound flexible pipe or a metal pipe provides an end pipe section of greater strength and weight that will not deviate and bend like a composite conduit and therefore eliminates the need to provide the lifting system with additional weight.

In accordance with the present invention, a hybrid elevator system is provided for the connection between a floating unit and an underwater unit as described in claim 1. The hybrid elevator system according to the invention has a lightweight and almost composite composite duct section. floating, which means less load impact on the floating unit. At least one end of the lifting system, that is, the end that is connected to the floating unit and / or the end that is connected to the underwater unit, is provided with an end pipe section that can resist or better accommodate the forces exercised in the elevator system in the vicinity of the floating and / or underwater unit where the elevator deviates and bends more. The lifting system of the invention reduces the upper tension, the contact bend curvature, the contact socket compression and the retention tension and is suitable for use at high hydrostatic pressures in deep and ultra deep waters.

According to an embodiment of the invention, said at least one end pipe section is arranged to be negatively floating.

According to another embodiment of the invention, the composite conduit is constituted by a single continuous conduit, that is, the composite conduit is connected to at least one end pipe section, but there are no other connections along the length of the elevator.

According to another embodiment of the invention, the lifting system has a lightweight and almost floating composite duct section to assume a neutral or slightly negative buoyancy.

In accordance with further embodiments of the invention, the elevator is adapted to assume a compatible configuration when installed, for example, free suspension (catenary), lazy in S or wave, or inclined in S or wave.

According to another embodiment of the invention, the composite conduit further comprises an outer protective cover, and optionally at least one reinforcing layer.

According to another embodiment of the invention, the upper and / or lower ends of the composite conduit section are terminated in a metal composite interface connector. According to a further embodiment of the invention, the composite conduit is flexible enough to be wound in a coil with a distribution radius of approximately 4500-8500 mm.

According to an embodiment of the invention, the composite conduit and said at least one end pipe section have an internal diameter in the range of about 10-40 cm (4-16 inches).

According to an embodiment of the invention, the length of the end pipe section that is connected to the floating unit is approximately 50-600 m. According to another embodiment of the invention, the length of the section of the end pipe that is connected to the underwater unit is approximately 50-100 m.

According to a further embodiment of the invention, the length of the composite conduit is approximately 1000-1500 m or more.

According to a further embodiment of the invention, the floating unit is a production or storage unit or a platform or vessel, the underwater unit is an underwater well installation, whereby the lifting system is adapted for the transport of fluids, in particular hydrocarbons, such as oil and / or gas, or injection fluids, such as methanol or water, between floating and underwater units.

Detailed description of the achievements

The present invention will be explained in more detail below by means of non-limiting examples with reference to the attached figures, where:

Figure 1 is a schematic view of an elevator according to an embodiment of the invention connected between a production vessel and an underwater installation.

Figure 2 shows a connector for connecting an end pipe section of an elevator to the central conduit section composed of the elevator,

Figure 3 is a cross section of the central composite duct section of an elevator according to an embodiment of the invention, taken along line A-A of Figure 2.

It should be noted that the drawings have not been drawn to scale and that the dimensions of certain features have been exaggerated for reasons of clarity.

Detailed description of the achievements

Figure 1 shows an elevator system 10 for the connection between a floating unit 12 and an underwater unit 14 located on the seabed 18. The floating unit 12 is, in the illustrated example, a floating production unit for processing well fluid, by removing gas and water, for example, from an underwater well assembly 14, and transporting the fluid to a pipe line export or unload it to another vessel, such as an oil tanker, whereby the elevator system 10 transports the fluid from the underwater unit 14 to the floating unit 12. The floating production unit 12 may alternatively, or also, have equipment for injecting water or gas into an underwater well 14 for production purposes, whereby the elevator 10 transports fluid from the floating unit 12 to the underwater unit 14.

An elevator 10 comprises a section 20 of upper metal end pipe, a central composite section 22 and a section 24 of lower metal end pipe. The upper end pipe section 20 has a length of about 50 to 600 m and is negatively floating. According to the invention, the entire upper end pipe section 20 and the lower end pipe section 24 are formed from a non-joined flexible pipe. The lower end pipe section 24 is connected to a submarine installation 14 at the underwater bottom 18, such as a multiple or production / injection shaft, in a horizontally displaced location of the production vessel 12. The elevator 10 is constructed to assume a compatible configuration when installed. As shown in Figure 1, the installed elevator 10 assumes a lazy wave configuration. The movement of the floating unit adapts to the flexibility of the section of the upper end pipe, that is, the unbound metal flexible pipe. No tension means are required to maintain the tension in the elevator 10. The tension is obtained through section 20 of the upper end pipe and buoyancy is optionally applied to section 22 of the composite central conduit to prevent compression in the elevator chain 10.

The section 22 of the composite central conduit constitutes the greater part of the length of the elevator 10, and is much longer than the section 20 of the upper end pipe or the lower end pipe section 24. For example, the distance from the vessel 12 to the underwater installation 14 could be 2,000 meters and the section 22 of the composite central duct would be 1,500 meters or more in length. Section 22 of the composite central duct is preferably neutral or slightly negative in buoyancy.

The lower end pipe section 24 is used in environments where flexibility is required to connect the lower end of the elevator 10 to an underwater installation 14 or where compression can occur. The lower end pipe section 24 may include a metal conical tension joint if necessary. The lower end pipe section 24 comprises a non-joined flexible pipe of the type described above. As shown in Figure 1, since the elevator 10 has a compatible configuration, a part of the bottom end pipe section 24 will probably be found at the bottom 18. The lower end pipe section 24 is also much shorter than the length of the section 22 of the composite central conduit, for example, the lower section 24 is preferably about 50 to 100 meters in length.

The, or each section of end pipe 20, 24, can be connected to the ground compound conduit 22 and stored in a reel for installation purposes or the end pipe section could be wound in a separate reel and connected to the composite conduit during the installation. The latter method would be more suitable when the end pipe sections comprise a metal pipe.

Figure 2 shows a flange type connector 26, made of metal, for example, for connecting a composite conduit 22 to an upper end pipe section 20 and / or a lower end pipe section 24. The connector 26 is secured by a plurality of bolts 28. The flange type connector 26 could be a standard API.

Alternatively, a more compact flange could be used, but also a flexible joint depending on the environment. The upper end pipe section 20 has a conventional float connection, for example, that couples the elevator 10 to the floating production unit 12. The float connection could include a flexible joint or a flange connection with a curvature reinforcement.

Figure 3 shows a cross section of the central duct section composed of the lifting system (the outer protective cover is not shown). According to an embodiment of the invention, the conduit 22 has a fluid impervious inner liner 30, which has an internal diameter typically ranging from about 15-30 cm (6-12 inches), which is continuous and extends from its upper end 20 to its lower end 24. The inner lining 30 may be formed from a conventional thermoplastic material, such as polyamides, polyvinylidene fluoride (PVDF), polyphenylene sulfide (PPS) or polyether ether ketone (PEEK), preferably with a thickness of between 4 and 7 mm . A tape 32 reinforced with thermoplastic fiber, such as carbon fiber or glass fiber, is wrapped around the liner 30 at various angles, depending on the loads and the environment. The tape 32 reinforced with thermoplastic fiber is then attached to the lining 30 or to the substrate of the tape, for example, with heat, which forms a lightweight and high strength tubular member. The upper and / or lower ends of the composite conduit section 22 are terminated in a metal composite interface connector 26.

At least one reinforcing layer can be added which is formed by unidirectional continuous carbon, glass or aramid fibers, which are embedded in thermoplastic resins. Typical thermoplastic resins are the following: polyamides (PA, PPA) polysulfone (PSU), polyetherimide (PEI) and polyether sulfone (PES) or polyether ether ketone (PEEK).

The invention, of course, is not restricted in any way to the preferred embodiments described above. On the contrary, many possibilities of modification thereof will be apparent to a person with ordinary experience in the art without departing from the basic idea of the invention as defined in the appended claims.

Claims (15)

1. A hybrid elevator system (10) for the connection between a floating unit (12) and an underwater unit (14) that is located at the sea floor (18), the system comprises: a flexible compound conduit (22) for transporting a fluid between said floating unit (12) and the underwater unit (14) whereby said composite conduit comprises a joined pipe having an inner lining (30); an end pipe section (20) connected to the composite conduit, said end pipe section (20) being adapted to connect between the floating unit (12) and the composite conduit; and an additional end pipe section (24) connected to the composite conduit, said end pipe section (24) adapting to connect between the underwater unit (14) and the composite conduit (22), whereby said end pipe sections (20, 24) comprise an unbound flexible metal pipe, the unbound flexible metal pipe comprising a plurality of metal layers, which are not bonded together and that move independently of each other , and where the elevator system is adapted to assume a compatible flexible configuration when installed. 2. An elevator system according to claim 1, characterized in that said end pipe sections (20, 24) are arranged to be negatively floating. 3. An elevator system according to claim 1 or 2, characterized in that the composite conduit (22) is constituted by a single continuous composite conduit. 4. An elevator system according to any of claims 1-3, characterized in that the composite duct section (22) is neutral or has negative buoyancy. 5. An elevator system according to claim 1, characterized in that said compatible configuration is a free suspension configuration. 6. An elevator system according to claim 1, characterized in that said compatible configuration is an S-lazy or lazy wave configuration. 7. An elevator system according to claim 1, characterized in that said compatible configuration is an inclined S or inclined wave configuration. 8. An elevator system according to any of the preceding claims, characterized in that the composite conduit (22) further comprises an outer protective cover, and optionally at least one reinforcing layer (32). 9. An elevator system according to any one of the preceding claims, characterized in that the upper and lower ends of the composite conduit section (22) are terminated in a metal composite interface connector (26). 10. A lifting system according to any of the preceding claims, characterized in that the composite conduit (22) is flexible enough to be wound on a reel with an axis radius of approximately 4500-8500 mm. An elevator system according to any of the preceding claims, characterized in that the composite conduit (22) and said end pipe sections (20, 24) have an internal diameter in the range of approximately 10-40 cm. 12. An elevator system according to any of the preceding claims, characterized in that the length of the end pipe section (20) that is adapted to be connected between the floating unit and the composite conduit (12) is approximately 50-600 m. 13. An elevator system according to any of the preceding claims, characterized in that the length of the section (24) of the end pipe which is adapted to be connected between the underwater unit and the composite conduit is approximately 50-100 m. 14. An elevator system according to any of the preceding claims, characterized in that the length of the composite conduit (22) is approximately 1000-1500 m or more. 15. An elevator system according to any of the preceding claims, characterized in that the floating unit (12) is a production or storage unit or a platform or vessel, and the underwater unit (14) is an underwater well installation, in where the elevator system (10) is adapted for transport of fluids, in particular hydrocarbons, such as oil and / or gas, or injection fluids, such as methanol or water, between the floating (12) and underwater (14) units.