Abstract:
The present inventions relate generally to umbilicals comprising at least one inner tube and at least one composite fiber element to provide greater resistance to radial compressive forces. Such umbilicals may be used in subsea hydrocarbon production applications.

Description:
PRIORITY INFORMATION 
   This application claims the benefit of U.S. Provisional Application No. 60/625,858, filed on Nov. 8, 2004. 

   FIELD OF INVENTION 
   The present inventions relate generally to umbilicals comprising at least one inner tube and at least one composite fiber element to provide greater resistance to radial compressive forces. Such umbilicals may be used in subsea hydrocarbon production applications. 
   BACKGROUND OF THE INVENTION 
   Umbilical cables are used to supply power and/or control signals from a topside structure such as a platform to equipment located subsea, such as a remotely operated vehicle “ROV”. Due to increased operating/installation depths of umbilical systems, umbilicals are typically subjected to increasingly higher levels of radial compression forces, e.g. by installation equipment during the actual installation process. The present inveniton relates to the use of composite fiber beam elements and/or composite taping layers and/or composite fibers which may be incorporated directly into umbilicals when those umbilicals are being manufactured, e.g. during an extrusion process. In this manner, compressive forces may be distributed throughout the umbilical structure. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross sectional view of a preferred embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1  illustrates a cross-section of a preferred embodiment of an umbilical according to the present inventions. A preferred embodiment of the present invention comprises an inner section  10  comprising at least two inner tubes  12 . In one preferred embodiment, the inner section comprises at least three inner tubes arranged in a triangular configuration wherein a composite fiber element is positioned between each pair of adjacent inner tubes, as illustrated in  FIG. 1 . In another preferred embodiment, the inner section has a circular cross sectional area, as shown in  FIG. 1 . This embodiment further comprises a composite fiber element  30  positioned between the two inner tubes and a composite tape  16  surrounding the inner section. In the preferred embodiment shown in  FIG. 1 , the inner tubes  12  are positioned beside each other. 
   A preferred embodiment of the invention further comprises an outer annular section  18  surrounding the composite tape and comprising at least one outer tube  20  and one transmission cable  22 . In one preferred embodiment, the transmission cable is electrically conductive. In another preferred embodiment, the transmission cable is a fiber optic cable. 
   This embodiment of the invention further comprises a composite fiber element  30  positioned between the outer tube and the transmission cable, and an outer wall  24  surrounding the outer annular section. In another preferred embodiment, the inner section is concentrically located, relative to the outer annular section, as shown in  FIG. 1 . In another preferred embodiment, the outer wall has a circular cross section. 
   In a preferred embodiment, each composite fiber element has a cross sectional area comprising a central elongated region  32  comprising a first end  34 , and a second end  36 . In this preferred embodiment, the composite fiber element further comprises a first flared region  37  connected to the first end, and a second flared region  38 , connected to the second end, as shown in  FIG. 1 . In another preferred embodiment, each flared region is circular. In yet another preferred embodiment, at least one composite fiber element comprises a region having a substantially circular cross section, as shown in  FIG. 1 . 
   In one preferred embodiment, the outer annular section comprises at least two outer tubes located on substantially opposing sides of the inner section, at least two transmission cables, each of which are located between two outer tubes, and a composite fiber element located between each adjacent pair of outer tubes and transmission cables, as shown in  FIG. 1 . 
   Using composite fiber beam elements and/or composite taping layers and/or composite fibers which may be incorporated directly into umbilicals, a more robust umbilical design may be realized, allowing installation and use of umbilicals in deeper water without requiring upgrading of installation equipment. In addition to radial support, an umbilical of the present inventions may also be used as an axial tension member, e.g. by terminating them in umbilical strength terminations in such a way was to share axial loads with one or more existing tension members. In this embodiment, the umbilical comprises a first end region comprises a termination having equivalent strength to that of the remainder of the umbilical. Such a termination is illustrated in  FIG. 1 . Such tension members are typically steel tube components and/or steel armor layers. In another embodiment, the first end of the umbilical is connected to an axial tension member with which the first end of the umbilical shares an axial load. 
   The foregoing disclosure and description of the inventions are illustrative and explanatory. Various changes in the size, shape, and materials, as well as in the details of the illustrative construction and/or a illustrative method may be made without departing from the spirit of the invention.