WO2010070324A1

WO2010070324A1 - Subsea umbilical

Info

Publication number: WO2010070324A1
Application number: PCT/GB2009/051689
Authority: WO
Inventors: Alan Dutton; Alan Rutherford
Original assignee: Technip France
Priority date: 2008-12-18
Filing date: 2009-12-11
Publication date: 2010-06-24
Also published as: GB0822999D0; GB2466262A

Abstract

An umbilical (1) for use in the offshore production of hydrocarbons comprising at least one thermoplastic hose (20), the thermoplastic hose comprising at least an inner polymeric liner (7), a first reinforcement layer (11), a second reinforcement layer (9) and an external polymeric sheath (10), wherein the first reinforcement layer (11) comprises at least one non-woven winded layer of high tenacity fibres, and the second reinforcement layer comprises at least one interwoven winded layer of high tenacity fibres.

Description

SUBSEA UMBILICAL

The present invention relates to an umbilical comprising thermoplastic hoses for use in the offshore production of hydrocarbons.

In subsea oil field operations, umbilicals are used to transport fluids, power, signals or data to and from a subsea installation. An umbilical comprises a group of one or more types of functional elements such as electric cables, optical fibre cables, or hoses for fluid transportation of, for example, gas, water or chemical products such as methanol. These functional elements are assembled together in a helical or S/Z manner and over-sheathed and/or over-armoured for mechanical strength and ballast. It is desirable for a single umbilical to be able to contain as many functional elements as are required for a particular application, for example, as are required for a particular oil field where the umbilical is intended for use.

The document API 17E "Specification for Subsea Umbilicals" published by the American Petroleum Institute provides standards for the design and manufacture of such umbilicals.

The main hoses used for manufacturing umbilical are thermoplastic hoses and steel tubes. Thermoplastic hoses are more flexible than steel tubes, which reduces the stiffness of the umbilical, and can be easily assembled in a S/Z manner, contrary to steel tubes, which reduces the manufacturing costs.

Thermoplastic hoses typically comprise a thermoplastic liner covered by one or more reinforcement layers being covered by a thermoplastic sheath. The purpose of the reinforcement layer(s) is to contain the pressure in the hose. Each layer generally comprises high tenacity composite fibres such as aramid fibres. These fibres are applied in the form of woven or interwoven braid, with braiding angles ranging from 30° to 70° depending on the application and the desired properties of the hose. If one interwoven braid reinforcing layer is insufficient to contain the pressure, additional similar reinforcing layer can be added. The accompanying Figure 2 shows a conventional thermoplastic hose having two woven winded reinforcement layers 8, 9 around an inner liner 7.

In severe operating conditions combining high pressure and high dynamic loading over an extended period of time, such thermoplastic hoses may have their reinforcing layers damaged, and their performances reduced.

The object of the present invention is to minimise or overcome this disadvantage.

According to the invention, there is provided an umbilical for use in the offshore production of hydrocarbons comprising at least one thermoplastic hose, the thermoplastic hose comprising at least an inner polymeric liner, a first reinforcement layer, a second reinforcement layer and an external polymeric sheath, wherein the first reinforcement layer comprises at least one non-woven winded layer of high tenacity fibres, and the second reinforcement layer comprises at least one interwoven winded layer of high tenacity fibres.

According to a second aspect of the present invention, there is provided a thermoplastic hose comprising an inner polymeric liner, a first reinforcement layer, a second reinforcement layer and an external polymeric sheath, wherein the first reinforcement layer comprises at least one non-woven winded layer of high tenacity fibres, and the second reinforcement layer comprises at least one interwoven winded layer of high tenacity fibres.

Preferably, the thermoplastic hose has an unbonded construction. In the present application, "unbonded construction" means a structure where the polymeric and reinforcing layers of the hose are separate unbonded layers, which allow relative movement between layers.

Preferably, the high tenacity fibres are aramid fibres.

According to one embodiment of the present invention, the first reinforcement layer comprises at least two non-woven winded layers, such as two or three layers. Preferably, the at least two layers of the first reinforcement layer are contrary-winded around the inner polymeric liner. That is, the layers are winded in a contrary direction, such as in opposite directions.

According to another embodiment of the present invention, the or each winded layer of the first reinforcement layer is helically winded around the inner polymeric liner. The helical winding(s) provide a spiral braiding with a tight and uniform braid.

Preferred embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:-

Figure 1 is a cross section of a subsea umbilical according to an embodiment of the present invention; Figure 2 is a side elevation view cross of a thermoplastic hose according to the prior art; and

Figure 3 is a side elevation view cross of a thermoplastic hose according to an embodiment of the present invention.

As illustrated in Figure 1 , a subsea umbilical 1 contains a plurality of functional elements, including several thermoplastic hoses, and electric or optical cables generally labelled 3. These functional elements are assembled in helical or S/Z manner together with fillers 4 and over- sheathed 6 and armoured layers 5 to form the umbilical.

As illustrated in Figure 2, a prior art thermoplastic hose 2 suitable for an umbilical 1 comprises an inner polymeric liner 7 covered by at least one reinforcing layer 8 and an external polymeric sheath 10. High pressure hoses generally comprise two reinforcing layers 8,9. Each reinforcing layer 8,9 is made of two layers of helically cross winded fibres, roves or yarns which have been woven or interwoven in a manner known in the art. The fibres are made with high strength composite material such as aramid. This interwoven braid construction confers a good geometrical stability to the reinforcing layer.

However it has been found that under severe cyclic pressure conditions, the interwoven braid 8 in direct contact with the inner tube 7 may be damaged over a long period of time.

Figure 3 illustrates a solution to this problem according to a preferred embodiment of the present invention. Starting from the inside, a hose 20 according to one embodiment of the present invention comprises an inner polymeric liner 7, a first reinforcing layer 11 , a second reinforcing layer 9, and an external polymeric sheath 10. The second reinforcing layer 9 has an interwoven construction similar to the reinforcing layers 8, 9 shown in Figure 2.

The first reinforcing layer 11 comprises two separate and helically cross winded layers 12, 13 of high tenacity fibres or rovings or yarns of fibres. These two layers 12, 13 are simply winded one on top the other without any weaving, interweaving or interlacing.

The first reinforcing layer 11 is therefore free from the numerous crossover points of the interwoven construction of the first reinforcing layer of a conventional hose 2 shown in Figure 2. This provides a better mechanical behavior under high pressure dynamic conditions. Furthermore, the dimensional stability of the first reinforcing layer 11 , although smaller than the one of the prior art interwoven first reinforcing layer 8, remains compatible with the requirements of the application of the hose 20 in use. Meanwhile, the risk of forming excessive gaps between adjacent yarns or fibres is limited by the second reinforcing layer 9 which has a very stable interwoven design and this can efficiently prevent the first reinforcing layer 11 from swelling.

The second reinforcing layer 9 of the hose 20 has crossover points which may seem to remain as weak points under high pressure cyclic conditions, however, as the first reinforcing layer 11 takes a significantly higher percentage of the load (typically 65% for the first reinforcing layer and 35% for the second reinforcing layer), the second reinforcing layer 9 is not stressed enough to be damaged at its crossover points. In this preferred embodiment, the hose 20 of the present invention has an unbonded construction and the first reinforcing layer 11 is in direct contact with the inner liner 7.

In an alternative embodiment not represented, an additional layer is intercalated between the inner liner 7 and the first reinforcement layer 11. This additional layer can be an adhesive layer, which leads to a bonded construction, and increases the dimensional stability of the first reinforcement layer 11. Alternatively, this additional layer can be a third reinforcing layer consisting in two interwoven cross winded layers of high tenacity fibres (and having a similar structure as the second reinforcing layer 9).

Preferably, the high tenacity fibres of the reinforcing layers are meta aramid fibres, such as the homopolymer commercialized by Du Pont under the trade name Kevlar, or the copolymer commercialized by Teijin under the trade name Technora.

Various modifications and variations to the described embodiments of the inventions will be apparent to those skilled in the art without departing from the scope of the invention as defined in the appended claims. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments.

Claims

1. An umbilical for use in the offshore production of hydrocarbons comprising at least one thermoplastic hose, the thermoplastic hose comprising at least an inner polymeric liner, a first reinforcement layer, a second reinforcement layer and an external polymeric sheath, wherein the first reinforcement layer comprises at least one non-woven winded layer of high tenacity fibres, and the second reinforcement layer comprises at least one interwoven winded layer of high tenacity fibres.

2. An umbilical according to claim 1 , wherein the thermoplastic hose has an unbonded construction.

3. An umbilical according to claim 1 or 2 wherein the high tenacity fibres are aramid fibres.

4. An umbilical according to any one of claims 1 to 3 wherein the first reinforcement layer comprises at least two non-woven winded layers.

5 An umbilical according to claim 4 wherein the at least two layers of the first reinforcement layer are contrary-winded around the inner polymeric liner.

6. An umbilical according to any one of the preceding claims wherein the or each winded layer of the first reinforcement layer is helically winded around the inner polymeric liner.

7. A thermoplastic hose comprising an inner polymeric liner, a first reinforcement layer, a second reinforcement layer and an external polymeric sheath, wherein the first reinforcement layer comprises at least one non-woven winded layer of high tenacity fibres, and the second reinforcement layer comprises at least one interwoven winded layer of high tenacity fibres.

8. A thermoplastic hose according to claim 7 wherein the thermoplastic hose has an unbonded construction.

9. A thermoplastic hose according to claim 7 or claim 8 wherein the first reinforcement layer comprises at least two non-woven winded layers.

10. A thermoplastic hose according to claim 9 wherein the at least two layers of the first reinforcement layer are contrary-winded around the inner polymeric liner.

11. A thermoplastic hose according to any one of claims 7 to 10 wherein the or each winded layer of the first reinforcement layer is helically winded around the inner polymeric liner.

12. A thermoplastic hose according to any one of claims 7 to 11 wherein the high tenacity fibres are aramid fibres.