An arrangement and a method for the installation of data and electrical transmission lines on a steel lazy wave riser (slwr)

Abstract

An arrangement of an umbilical of data communication lines and/or electrical energy transmission lines is mounted on a lazy wave catenary riser. The umbilical has a first section extending from an upper hang off location of the riser continuously downward to a first installation point at the riser and a second section extending from a second installation point at the riser continuously downward to the sea bed at a riser touch down location. The first installation point is positioned in an installation region of the riser between a lowest sag bend point and a highest hog bend point of the lazy wave catenary riser extension. The first 1 section is tensioned to a flatter catenary shape than a catenary shape of the riser between the upper hang off location and the first installation point, so that a portion of the first section extends detached from the riser.

1 . An arrangement of an umbilical of data communication lines and/or electrical energy transmission lines mounted on a lazy wave catenary riser comprising:
 A) the lazy wave catenary riser, the lazy wave catenary riser comprising (2) having:   an upper catenary section extending from an upper hang off location at a floating production storage offloading (FPSO) facility downwards and transitioning in a sag bend having a lowest sag bend point and an upward oriented end section,   a buoyant section having buoyant devices attached to the riser and extending from the upward oriented end section of the sag bend further upward and forming a hog bend of opposite curvature with respect to the sag bend and defining a highest hog bend point and a downward oriented end section, so that the sag bend and the hog bend define a double curvature section and an inflection location between the sag bend and the hog bend,   a lower catenary section extending from the downward oriented end section of the hog bend further downward and then converging towards a horizontal orientation at a touch down location on the sea bed,   wherein the a course of the riser has, in addition to a vertical component, a continuously growing horizontal component in a horizontal riser direction starting from the upper hang off location towards the touch down location,   B) the umbilical, the umbilical comprising:   a first umbilical section extending from the upper hang off location continuously downward to a first installation point at the riser,   a second umbilical section extending from a second installation point at the riser continuously downward to the sea bed at the touch down location, wherein:   the first installation point is positioned in an installation region of the riser between the lowest sag bend point and the highest hog bend point, and the first umbilical section is tensioned to a flatter catenary shape than the a catenary shape of the riser between the upper hang off location and the first installation point, so that between the upper hang off location and the first installation point the first umbilical section extends at a distance and detached from the riser.   
     
     
         2 . An arrangement according to  claim 1 , wherein the second installation point is positioned in the installation region of the riser between the lowest sag bend point and the highest hog bend point, and the second umbilical section has a catenary shape with an opposite curvature to the curvature of the buoyant section, so that between the second installation point and the touch down location the second umbilical section extends at a distance and detached from the riser. 
     
     
         3 . An arrangement according to  claim 2 , wherein the first umbilical section extends at a distance above and in the horizontal riser direction with respect to the riser between the upper hang off location and the first installation point, whereas the second umbilical section extends at a distance below and opposite the horizontal riser direction with respect to the riser between the second installation point and the touch down location. 
     
     
         4 . An arrangement according to  claim 1 , wherein the first and second umbilical sections have different longitudinal pretension forces, or the first umbilical section has a higher pretension force than the second umbilical section. 
     
     
         5 . An arrangement according to  claim 1 , wherein the installation region is confined within a distance from the inflection location smaller than 2%, of a total length of the riser from the upper hang off location to the touch down location. 
     
     
         6 . An arrangement according to  claim 1 , wherein the first installation point and the second installation point are within a maximum distance of 25 meters from the inflection location and the third umbilical section has a length of less than 50 meters. 
     
     
         7 . An arrangement according to  claim 1 , wherein the umbilical comprises a third umbilical section extended between the first installation point and the second installation point and making an electrical and/or data communication connection between the first umbilical section and the second umbilical section,
 the third umbilical section having a length greater than a straight distance between the first installation point and the second installation point.   
     
     
         8 . An arrangement according to  claim 1 , comprising one or more branch lines with one or more of data transmission cables and electricity cables, branched off from the umbilical and extending to monitoring locations at the riser. 
     
     
         9 . An arrangement Arrangement according to  claim 8 , wherein said branch lines comprise one or more of:
 a sag bend branch line extending to a sag bend monitoring location at the sag bend of the riser, and   a hog bend branch line extending to a hog bend monitoring location at the hog bend of the riser, and   an upper branch line extending to an upper monitoring location along a portion of the upper catenary section of the riser, and   a lower branch line extending to a lower monitoring location along a portion of the lower catenary section of the riser.   
     
     
         10 . An arrangement according to  claim 1 , wherein the first installation point and the second installation point are each formed by an installation structure having:
 a reversable mechanical riser coupler for a mechanical connection of the installation structure with the riser, and   one or more mechanical pull resistant umbilical couplers for a mechanical connection of the installation structure with the umbilical,   an electrical and data distribution device comprising multiple communicating connecting sockets to enable a plurality of connections between the umbilical sections, and/or additional branch lines.   
     
     
         11 . An arrangement according to  claim 10 , wherein the installation structure is configured as a self-supporting clamping body having further comprising:
 a crane rigging attachment interface to enable the installation structure to be lifted, lowered and positioned by a crane,   a coupling actuation interface adapted to be engaged and operated by a remotely operated subsea vehicle for engaging and releasing the mechanical riser coupler,   wherein the mechanical riser coupler comprises opposing jaws.   
     
     
         12 . An arrangement according to  claim 1 , wherein at the touch down location, a lower end of the second umbilical section is mechanically connected with a mud mat placed on the sea bed, said mud mat comprising:
 a mechanical umbilical coupler, and   an electrical and data distribution device with a plurality of connecting sockets for electrical and data transmission connection of the second umbilical section and of additional branch lines.   
     
     
         13 . An arrangement according to  claim 1 , comprising a monitoring instrumentation with one or more of a pressure sensor, a temperature sensor, an accelerometer, a strain gauge, an optical sensor, a telecamera, connected to the umbilical and/or to one or more additional branch lines branched off the umbilical. 
     
     
         14 . A method for installing an umbilical of data communication lines and/or electrical energy transmission lines on a lazy wave catenary riser for obtaining the arrangement according to  claim 1 , comprising the step of installing the first umbilical section by:
 positioning a deploy vessel, different from the FPSO which defines the upper hang off location, above the installation region of the riser and paying out and lowering the first umbilical section from the deploy vessel until a lower end of the first umbilical section reaches the first installation point in the installation region,   while the deploy vessel holds an upper end of the first umbilical section, mechanically coupling the lower end of the first umbilical section with the riser in the first installation point by using a remotely operated subsea vehicle,   moving the deploy vessel to the FPSO and contemporaneously paying out an additional length of the first umbilical section from the deploy vessel,   transferring the upper end of the first umbilical section from the deploy vessel to the FPSO and fixating the upper end of the first umbilical section in the upper hang of location of the riser at the FPSO,   tensioning the first umbilical section to a flatter catenary shape than the catenary shape of the riser between the upper hang off location and the first installation point, so that between the upper hang off location and the first installation point the first umbilical section extends at a distance from the riser   
     
     
         15 . The method according to  claim 14 , comprising the step of installing the second umbilical section by:
 positioning the deploy vessel, different from the FPSO which defines the upper hang off location, above the touch down location of the riser and paying out and lowering the second umbilical section from the deploy vessel until a lower end of the second umbilical section reaches the touch down location,   while the deploy vessel holds an upper end of the second umbilical, mechanically coupling the lower end of the first umbilical section in the touch down location, by using the remotely operated subsea vehicle,   moving the deploy vessel to a location above the installation region of the riser and contemporaneously lowering the upper end of the second umbilical section from the deploy vessel,   mechanically coupling the upper end of the second umbilical section with the riser in the second installation point, by using the remotely operated subsea vehicle.   
     
     
         16 . The method according to  claim 15 , comprising the step of making an electrical and/or data transmission connection between the first umbilical section and the second umbilical section in the installation region by installing a third umbilical section by:
 electrically and/or data transmission connecting a first end of the third umbilical section to the lower end of the first umbilical section in the first installation point, by using the remotely operated subsea vehicle,   electrically and/or data transmission connecting a second end of the third umbilical section to the upper end of the second umbilical section in the second installation point, by using the remotely operated subsea vehicle.   
     
     
         17 . The method according to  claim 14 , comprising the step of connecting to the umbilical one or more branch lines having one or more of data transmission cables and electricity cables, using the remotely operated subsea vehicle, and extending the one or more branch lines to monitoring locations at the riser. 
     
     
         18 . The method according to  claim 14 , comprising the step of coupling the lower end of the first umbilical section to a first installation structure prior to lowering the first umbilical section from the deploy vessel and coupling the lower end of the first umbilical section to the riser by clamping the first installation structure on the riser. 
     
     
         19 . The method according to  claim 15 , comprising the step of coupling the upper end of the second umbilical section to a second installation structure prior to lowering the upper end of the second umbilical section from the deploy vessel and coupling the upper end of the second umbilical section to the riser by clamping the second installation structure on the riser.