Flexible Pipe

(54) Title: FLEXIBLE TUBE (30) Unionist Priority: 06/28/2007 gb 0712586.7 (73) Owner (s): Wellstream International Limited (72) Inventor (s): Terence Sheldrake (57) Abstract: FLEXIBLE TUBE. Flexible tube apparatus and methods are disclosed, and the flexible tube body of composite tape for a flexible tube comprises an internal pressure coating and at least one shielding layer over the coating comprising a rolled tape of composite material. A method for making the composite tape is disclosed using a pultrusion process.

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ΡΙ0802161-9

FLEXIBLE TUBE

The present invention relates to a flexible pipe body that can be used to form a flexible pipe of the type suitable for transporting water; gas; mineral oil; crude oil; or similar production fluids. Specifically, but not exclusively, the present invention relates to a flexible tube body having one or more layers of shield formed from tape wrapped in a composite material.

Traditionally, the flexible tube is used to transport production fluids, such as oil and / or gas and / or water, from one location to another. Flexible pipe is particularly useful in connecting a location on the seabed to a location at sea level. The flexible pipe is generally formed as an assembly of a pipe body and one or more end connections. The tube body is typically formed as a combination of layered materials that form a conduit containing fluid and pressure. The structure of the tube allows great deflections without causing efforts and bending stresses that impair the functionality of the tube during its useful life. The tube body is generally constructed as a structure including metallic and polymer layers.

In many known flexible hose models the hose includes one or more layers of pressure shielding. The main charge on such layers is formed from radial forces. The pressure shielding layers tend to be coiled at a large angle to the longitudinal axis of the flexible pipe body and often have a specific cross-sectional profile for interlacing in order to be able to maintain and absorb the radial forces resulting from external pressure or on the tube. The cross-sectional profile of the rolled tapes that thereby prevent the tube from sagging or bursting, as a result of pressure, is sometimes referred to as the pressure-resistant profile.

In many known flexible hose models, the hose includes one or more layers of voltage shielding. The main burden on such a layer is tension. In high pressure applications, such as in deep water and ultra deep water environments, this stress shielding layer experiences high stress loads from the load of the internal pressure end cap as well as weight. This can cause the hose to fail as such conditions are experienced for extended periods of time.

The non-bonded flexible tube has been an enabling medium for developments in deep water (less than 1,005.84 meters) and in ultra-deep water (greater than 1005.84 meters) for more than 15 years. The technology allowed the industry to initially produce in deep water in the early 1990s and then in ultra-deep water up to approximately 1,981.2 meters in the late 1990s. Water depths greater than 1,981.2 meters extend the envelope where typical free-standing riser configurations, and flexible hose in general, can operate. The growing demand for oil is causing exploration to take place at greater depths where environmental factors are present.

are even more extreme. For example, in deep water and ultra deep water environments, the temperature of the seabed increases the risk of cooling production fluids to a temperature that can lead to blockage of the tube. Greater depths also increase the pressure associated with the environment in which the flexible pipe must operate. As a result, the need for high levels of performance from the pressure shield and voltage shield layers of the flexible pipe body is increased.

One way to improve the strength and thereby the performance of the shielding layers is to make the layers thicker and stronger and thereby more robust materials. For example, for pressure shielding layers in which layers are generally formed from ribbon wound with adjacent windings in the layer interlacing, fabricating the ribbon from thicker material results in the strength increasing appropriately. However, as more material is used, the weight of the flexible tube increases. Finally, the weight of the hose can become a limiting factor in the use of the hose. In addition, manufacturing the flexible pipe using increasingly thick material considerably increases the material cost, which is also a disadvantage.

It is an objective of the present invention to at least partially alleviate the problems mentioned above.

It is an objective of the modalities of the present invention to provide a flexible tube body that can be used in a flexible tube of a type capable of transporting production fluids and which includes a pressure shield layer or voltage shield layer or shield layers pressure and tension that are capable of operating effectively at great depths.

It is an object of the modalities of the present invention to provide a flexible tube body that can be used in a flexible tube of a type to carry fluids and which includes a shielding layer made in such a way as to be relatively light yet strong enough to performance according to the desired parameters.

It is an objective of the modalities of the present invention to provide layers in a flexible tube body which can flex when the flexible tube is flexed and yet which are strong enough to resist the bursting of an underlying coating of internal pressure such as a layer or barrier lining.

It is an objective of the modalities of the present invention to provide a riser, flow line or bridge assembly and method of manufacturing the flexible tube capable of operating in deep and ultra-deep water environments.

According to a first aspect of the present invention, a flexible tube body is provided for a flexible tube, comprising:

an internal pressure coating;

at least one layer of shielding over the liner comprising a rolled-up ribbon of composite material.

According to a second aspect of the present invention, a method of fabricating a flexible pipe body is provided, comprising the steps of:

wrap at least one layer of shield over an internal pressure coating by wrapping a tape of composite material over the coating.

In accordance with a third aspect of the present invention there is provided a method of making a composite tape using a pultrusion process, comprising the steps of:

providing a plurality of reinforcement fibers; impregnate the fibers with a resin mixture; heating the fibers and resin in a matrix; continuously pull the fibers through the matrix. Modalities of the present invention provide a flexible tube body in which at least the shield layer on top of the fluid retention layer is formed from a rolled-up ribbon of composite material. The composite material provides high strength, but in a controlled mass. For deep water operation where weight is an issue, the composite material matrix can be selected to be relatively light. For operations where the weight of the flexible tube is not a crucial design parameter, the matrix of the composite material from which the shield layer is manufactured can be formed from a selected heavy material which provides high strength and therefore high performance, but produces a relatively heavy flexible tube.

Modalities of the present invention provide a shielding layer in which the reinforcing fibers can be located, and / or molded, and / or manufactured from different materials in order to determine the performance characteristics of the rolled tape in use. For example, in specific areas of the tape where high tension should be expected when the adjacent windings are interlaced, a greater concentration of reinforcement filters can be provided. Alternatively, a greater or lesser concentration of reinforcement fibers may be provided close to an outer surface of the tape.

Modalities of the present invention provide that portions of the adjacent windings of a shield layer can be fused together by heating a composite tape matrix material beyond a predetermined temperature. Merging the adjacent windings together, in an integral form, can increase the overall strength. In order to provide flexibility of a shield layer provided in this fused form, points of weakness such as the narrowed neck regions can be formed in the cross section of the tape which is wrapped around the shield layer. Bending around the neck region narrowed in this way can occur when the flexible tube body needs to be flexed.

Modalities of the present invention provide a shield layer formed of interlaced windings in which an additional composite tape can be wound radially out of that interlaced shield layer. This improves overall performance. The additional reinforcement tape can be fused to the interlaced shield layer in order to improve the overall performance.

Modalities of the present invention will be described below, by way of example only, with reference to the accompanying drawings in which:

Figure 1 illustrates a flexible tube body;

Figure 2 illustrates a catenary riser;

Figure 3 illustrates a cross section of tape used to form a shield layer;

Figure 4 illustrates a cross section of the tape in which the reinforcement fibers have a non-uniform distribution;

Figure 5 illustrates adjacent windings in a shield layer in an interlaced shape;

Figure 6 illustrates a narrowed neck region and how the protrusions of adjacent windings fit into adjacent valleys;

Figure 7 shows interlacing windings superimposed by means of a flat composite tape; and

Figure 8 illustrates a manufacturing node.

In similar reference numeral drawings they refer to similar parts.

Throughout this specification, reference will be made to a flexible tube. It will be understood that a flexible pipe is an assembly of a flexible pipe body part and one or more end connections at each of which an end of the pipe body is terminated. Figure 1 illustrates how a tube body 100 is formed according to one embodiment of the present invention from a composite of layered materials that form a pressure containment conduit. Although some specific layers are illustrated in Figure 1, it should be understood that the present invention is broadly applicable to coaxial tube body structures, including two or more layers.

As shown in Figure 1, a tube body typically includes an innermost layer 101. The shell provides an interlaced metal construction that can be used as the innermost layer to prevent, totally or partially, the collapse of a pressure liner. internal 102 due to tube decompression, external pressure, voltage shield pressure and mechanical crushing loads. However, it will be considered that modalities of the present invention are applicable to smooth bore applications as well as rough bore applications.

The internal pressure liner 102 acts as

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The inner layer can itself comprise a number of sublayers. It will be considered that when a carcass layer is used, the retention layer is often referred to as a barrier layer. In operation without such a housing (so-called smooth bore operation) the fluid retention layer can often be referred to as a liner.

The pressure shield layer 103 is a structural layer with a seating angle close to 90 degrees that increases the resistance of the flexible tube to internal and external pressure and to mechanical crushing loads. The layer also structurally supports the internal pressure coating and typically consists of an interlaced metal construction. The pressure shielding layer is described in more detail below.

The flexible tube body may also include one or more layers of tape 104 and a first layer of strain shield 105 and a second layer of strain shield 106. Each layer of strain shield is a structural layer with a laying angle typically between 20 ° and 55 °. Each layer is used to support loads of tension and internal pressure. The voltage shield layers are typically wound in the opposite direction, in pairs.

The flexible tube body also includes an outer shell 108 which comprises a polymer layer used to protect the tube from penetration of seawater and other external environments, corrosion, abrasion and mechanical damage.

Each flexible tube comprises at least a portion, sometimes referred to as a pipe body segment or section 100 together with an end connection located on at least one end of the flexible tube. An end connection provides a mechanical device which forms the transition between the flexible pipe body and a connector. The different layers of tube, as shown, for example, in Figure 1, are terminated at the end connection in such a way as to transfer the load between the flexible tube and the connector.

Figure 2 illustrates a riser assembly

200 suitable for transporting production fluid such as oil and / or gas and / or water from and to a location on the seabed

201 for a floating installation 202. For example, in Figure 2 the location at the bottom of the sea 201 is a flow line at the bottom of the sea. The flexible flow line 205 comprises a flexible tube, integrally or in part, leaning on the seabed 204 or buried below the seabed and used in a static application. The floating installation can be provided by a platform and / or buoy or, as shown in Figure 2, a ship. The riser 12 is provided as a flexible riser, that is to say a flexible pipe connecting the ship to the installation on the seabed. The riser can be in segments with end connections and can be of hybrid structures optimizing either the stress or the collapse depending on the depth.

It will be considered that there are different types of riser tube, as is well known to those skilled in the art. Modalities of the present invention can be used with any type of riser, such as a freely suspended riser (free catenary riser), a riser contained to a certain extent (buoys, chains), riser fully contained or enclosed in a tube (tubes I or J).

Figure 2 also illustrates how the flexible tube body portions can be used as a flow line 205 or bridge 206.

Figure 3 illustrates a cross section of a tape formed by means of a pultrusion manufacturing process according to an embodiment of the present invention. As shown in Figure 3, the cross section of the ribbon is generally Z-shaped including two hump regions 301 and two valley regions 302. The cross section in this way has a generally convex and concave portion so that a convex portion of a winding can fit into a concave portion of an adjacent winding to thereby engage the adjacent windings. The tape 300 is formed of a matrix material 303 formed around reinforcement fibers 304 which extend longitudinally through the tape. The reinforcement fibers 304 shown in Figure 3 are distributed approximately uniformly and the position of these reinforcement fibers on the tape is determined during the manufacturing process by virtue of one or more guide plates as will be described in more detail below . The tape has a lower surface 305 and an upper surface 306. Each surface includes a shoulder region 307 where the surface is angled inwardly with respect to the rest of the surface.

It will be considered that although modalities of the present invention are described here with respect to a cross section in the shape and Z, other types of cross section profiles that can be interlaced, can be used for pressure shielding layers. It will also be considered that embodiments of the present invention can also be used, or can be used alternatively to provide the voltage shielding layers. In voltage shielding applications it will be considered that the adjacent windings do not need to interlace and thus a greater variety of cross section can be used.

Figure 4 illustrates a cross section of a tape that can be wrapped to form a shield layer in accordance with an alternative embodiment of the present invention, in that embodiment the sizes in cross section of the reinforcement fibers are different. Some 400 fibers have a relatively larger diameter while some additional 401 fibers have a smaller cross section. It should be noted that groups of fibers may be concentrated in selected regions, such as in regions where high loading stress is to be expected. It will be considered that by providing reinforcement fibers having a different cross section in different locations the performance of the tape can be somewhat controlled. For example, fibers of smaller diameters can be grouped close to an outer surface of the tape around the bulge and valley regions. This helps to prevent the protrusions from breaking during use when substantial forces can be experienced when adjacent windings in the shield layer are interlaced.

It will also be considered that, in addition or as an alternative for the selection of reinforcement fibers with different cross sections, the material from which the fibers are manufactured may be different. The fibers themselves can be of a wide variety of materials such as metal fibers, aramid fibers and / or glass fibers. For example, using small diameter aramid fibers in key locations can provide a good balance between overall cost and strength and performance of the shielding layer.

Figure 5 illustrates adjacent windings of a pressure shield layer 103 in a flexible tube body. A radially inner surface 305 of the tape is located nearby and conveniently in contact with the inner pressure liner 102. A protuberance of a convex portion of the rightmost thread 500 is illustrated to fit into a concave portion on the left most, adjacent to the rolling. As an example, a reinforcing fiber 502 of the wound tape is illustrated in Figure 5 as having an elliptical cross section. It will be considered that the shape in cross section as well as the diameter / size of the reinforcement fibers can be selected according to the modalities of the present invention.

The contact region 504 between the adjacent windings can be fused together, according to the modalities of the present invention. This is achieved during the fabrication of the shield layer 103 by providing localized heating as well as by induction heating in regions where the adjacent windings intertwine. Conveniently, a melt welding / bonding process can alternatively or additionally be used to fuse the windings together. The heat is raised above a predetermined temperature so that the matrix material in the windings melts together. Heating may occur beyond a material softening point or melting point. If the softening point is used, pressure can be applied to assist in the melting process. By melting the matrix material of adjacent windings together, the adjacent windings effectively become integrally formed. This produces a strong shield layer that helps to reduce the likelihood of the underlying fluid retention layer 102 bursting between the clearances in the shield layer.

It will be considered that more properly than fusing adjacent windings together, adhesive can be used to connect the winding portions together.

It will be considered by those skilled in the art that if adjacent windings are fused together, the flexibility of the layer will be reduced which may impede the flexibility of the flexible tube as a whole. To overcome such problems, a neck region narrowed in at least one position of the tape is provided. An example of this is illustrated in Figure 6. Here, the narrowed neck region 600 is provided by forming an outer notch 601 and an inner notch 602. This can be achieved by selecting a mold / die format which includes such notches or by removing part of the tape where the notches are desired. The narrowed neck region 600 thus acts as a pivoting mechanism allowing the flexible tube to flex in two directions. It will be considered that the narrow neck region can be formed according to a wide variety of options. For example, more properly than forming the notch of the tape may be such that the outer surfaces of the tape are angled inward to a narrowed point. It will also be considered that one can narrowly be formed on only one side of the tape yet to the extent that an articulating action is maintained.

Figure 7 illustrates how a reinforcement tape 700 can be wrapped around an outer surface of the shield layer 102. Reinforcement tape 700 can be of a well-known variety used by those skilled in the art in order to restrict movement in the direction out of the windings in order to prevent the tapes from becoming non-interlaced or (particularly in the case of tension shield layers) moving radially outward. Conveniently the reinforcement tape 700, as shown in Figure 7 is a composite tape having a substantially flat profile. The tape includes a matrix material 701 with the reinforcement fiber 702 extending longitudinally therethrough. The winding of the tape layer 700 can be formed of a matrix material 701 which combines with the matrix material 303 of the shielding tape. If used, the polymer combination of the matrix materials means that the shield tape layer can be fused to the reinforcement tape layer in selected regions 703. Conveniently the entire outer surface of the shield layer tape is fused to the outer layer of reinforcement tape except for the shoulder regions of the shield layer tape where the tape is distanced from reinforcement tape 700.

Figure 8 illustrates a pultrusion manufacturing process for producing composite tape to form a shield layer or reinforcement tape layer in accordance with the modalities of the present invention. Coils 800 are loaded with spools of reinforcement fibers having a desired cross section / shape or material. The process is a pultrusion process which involves pulling the fiber from the left side of Figure 8 to the right side of Figure 8. The fibers are located in desired locations using a guide plate 801 that helps to position the fibers in desired locations in the final product. An 802 resin impregnator contains a mixture of liquid resin (which may optionally contain resin, fibers, pigment or specialized additives). The fibers are pulled through the liquid resin material and then through a heated preform stage 803. The resin impregnator saturates the reinforcement fibers with a solution. The interior of the resin impregnator can be carefully designed to optimize the reinforcement wetting process in order to obtain complete or almost complete saturation of the fibers.

Upon exiting the resin impregnator, the reinforcement fibers can again be organized and positioned for eventual placement within the cross section. The preform

803 it is a rigging arrangement that compresses the excess resin when the product moves in order to start molding the materials before entering the matrix.

A matrix 804 having a predetermined shape is heated in order to activate a thermal consolidation reaction and to cure the composite. Upon leaving, the cured profile is pulled by an 805 traction system and can be cut to predetermined lengths by an 806 cutter. It will be considered that various types of heating mechanisms can be used during the pultrusion process and that various cooling stages can be used to cool the product as will be considered by those skilled in the art.

Modalities of the present invention also refer to the manufacture of a flexible tube body and a flexible tube using a portion of such a flexible tube body. During manufacture an internal pressure coating such as a barrier layer or liner is provided in a manufacturing knot and then the composite tape, as described above, is helically wound around the pressure coating. When the tape is wound, adjacent windings are interwoven to form a pressure shield layer. In the manufacturing node, heating elements, such as induction or fusion heating elements (not shown), can be included to provide localized heating to fuse parts of the adjacent windings together.

An internal housing can be formed within the internal pressure coating for rough hole application, the pressure coating thereby forming a barrier layer.

Optionally an additional composite tape layer can be wrapped around the interlaced pressure shield layer. This additional reinforcement tape layer may have the same profile, or different profile, in cross section and conveniently be a substantially flat strip having a polymer of matrix material combining with the matrix material of the shield layer. The heating elements, again, can be located to provide localized heating to fuse parts of the reinforcement tape into the underlying windings.

Outer layers, such as voltage shielding layers, insulation layers and an outer covering layer can later be formed.

In accordance with embodiments of the present invention in addition or as an alternative to provide the pressure shield layer as a composite ribbon wound one or more tension shield layers can be formed by coiling the composite ribbon in a coaxial manner with the internal pressure coating. The cross section of the voltage shield layer can be interlaced, but it will conveniently have a simple or circular rectangular cross section. Portions of adjacent windings can be fused or bonded together.

Throughout the description and claims of this specification, the terms understand and contain and variations of the terms, for example, comprising and understand, mean including, but not limited to, and are not intended to exclude (and do not exclude) other fractions, additives, components , wholes, or stages.

Throughout the description and claims of this descriptive report, the singular encompasses the plural unless the context requires otherwise. Specifically, where the indefinite article is used, the specification should be understood as considering the plurality as well as the singularity5 of, unless the content requires otherwise.

Characteristics, wholes, resources, compounds, chemical fractions or groups described together with a specific aspect, modality or example of the invention should be understood as applicable to any other aspect, modality or example described here unless it is incompatible with it.