Abstract:
An apparatus and method for connecting an umbilical to a marine riser is provided. The method and apparatus can be employed in instances when a riser is already in place in the water, extending from a drilling vessel to subsea equipment on the ocean floor.

Description:
TECHNICAL FIELD 
     The field of the invention is subsea drilling, including methods and apparatus for securing an umbilical to a subsea riser. 
     BACKGROUND 
     In subsea drilling operations, a marine riser with an attached umbilical is often deployed from a drill ship or platform to the sea floor. The umbilical can be configured to support subsea components, for example, the umbilical could be configured to provide subsea components with electrical, hydraulic, and optical power and control signals as well as chemical and gas delivery. A subsea umbilical is typically connected to a subsea riser concurrent with the subsea deployment of the riser. The connected assemblies of the riser and umbilical are then lowered together into the subsea environment as an integrated unit. Deploying the umbilical together with the riser allows the riser to provide support to the umbilical. However, this method can cause the deployment of the riser to be slower than otherwise possible. In addition, the known deployment methods can make servicing the riser or umbilical more difficult than otherwise because the umbilical is attached to and supported by the riser. There is a need for improved apparatus and methods for deploying and securing umbilicals. 
     SUMMARY 
     The present disclosure provides an apparatus and method for connecting an umbilical to a marine riser. The apparatus and method may be used when an umbilical is deployed independently of the deployment of the riser. The term ‘independently’ is used herein to mean that the umbilical is not necessarily coupled to the drilling riser during the time when the umbilical is lowered to the sea floor. For example, the method and apparatus can be employed in those instances when a riser is already in place in the water, extending from a drilling vessel to subsea equipment on the ocean floor. Such a deployment method is disclosed in provisional application Ser. No. 61/422,557, filed on Dec. 13, 2010, which is hereby incorporated by reference in its entirety. 
     The method of the present disclosure may include securing the umbilical to the riser with the assistance of a remotely operated subsea vehicle (“ROV”). The method also may include releasing the umbilical from the riser and retrieving it without removing the riser from the subsea environment. 
     The apparatus of the present disclosure may be in the form of an umbilical guide assembly which itself can be deployed and manipulated using a remotely operated subsea vehicle. In one embodiment of the invention, a number of umbilical guide assemblies may be employed in a spaced apart arrangement upon the riser assembly to secure an umbilical laterally and approximately parallel to a riser. This may be accomplished in a manner that allows for movement of the umbilical longitudinally with respect to the riser, which may be desirable. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a schematic illustration of a guide assembly in operation connected between a riser and an umbilical; 
         FIG. 2  is a top perspective view of the guide assembly according to the present disclosure with its umbilical interface in a closed position and its riser interface in a lock position; 
         FIG. 3  is a top perspective view of the guide assembly of  FIG. 2  with its umbilical interface in an open position and its riser interface in an unlocked position; 
         FIG. 4  is a bottom perspective view of the guide assembly of  FIG. 2 ; 
         FIG. 5  is a side view of the guide assembly of  FIG. 2 ; 
         FIG. 6  is a top view of the guide assembly of  FIG. 2  with its umbilical interface in a closed position; 
         FIG. 7  is a top view of the guide assembly of  FIG. 2  with its umbilical interface in an open position; 
         FIG. 8  is a cross-section of a portion of the umbilical interface of  FIG. 2 ; 
         FIG. 9  is a perspective view of an alternative embodiment of the guide assembly of  FIG. 2 . 
         FIG. 10  is an illustration of the guide assembly of  FIG. 2  being transported to the riser by a remotely operated vehicle; 
         FIG. 11  is an illustration of the guide assembly of  FIG. 2  being connected to the riser by the remotely operated vehicle; 
         FIG. 12  is an umbilical being connected to the guide assembly of  FIG. 2  by the remotely operated vehicle; and 
         FIG. 13  is a cross-section of a portion of an alternative embodiment of the umbilical interface of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , the umbilical guide assemblies  10  are shown in operation. In the depicted embodiment the guide assemblies  10  are shown spaced apart vertically along a riser  12  and connected between the riser  12  and the umbilical  14 . The guide assemblies  10  are configured to enable installation of the umbilical after the riser  12  has been fully deployed from the drilling vessel  16  and secured to the sea floor  18 . The guide assemblies  10  are also configured to make it possible to retract the umbilical from the sea without disrupting the riser. 
     Referring to  FIGS. 2-8 , an embodiment of the guide assembly  10  is shown in greater detail. The guide assembly  10  includes an umbilical interface assembly  20  configured to interface with an umbilical, a riser interface assembly  22  configured to interface with the riser, and a frame assembly  24  that extends between the umbilical interface assembly  20  and the riser interface assembly  22 . It should be appreciated that many other alternative embodiments of the present disclosure exist. 
     In the depicted embodiment umbilical interface assembly  20  includes a clam shell portion  26  and an umbilical interface actuation assembly  28 . The clam shell portion  26  is configured to be driven to an opened orientation by the umbilical interface actuation assembly  28  wherein it is arranged to receive a segment of umbilical  14  and configured to be driven to a closed orientation by the umbilical interface actuation assembly  28  wherein it retains the segment of umbilical  14  therein. The clam shell portion  26  is shown in a closed orientation in  FIGS. 2, 4, and 6  and shown in an open orientation in  FIGS. 3 and 7 . 
     In the depicted embodiment the clam shell portion  26  is configured to limit the movement of the umbilical in the horizontal plane (x-y plane) while allowing the umbilical to move freely in a vertical direction (z-direction). In the depicted embodiment, the clam shell portion  26  includes a generally cylindrical body having a first portion  30  that pivots relative to the second portion  32 . In the depicted embodiment the first portion  30  moves about axis AA while the second portion  32  is stationary when the umbilical interface actuation assembly  28  is actuated. See  FIGS. 6 and 7 . In the depicted embodiment the first portion  30  pivots through at least 60 degrees (e.g., 90, degrees, 110 degrees) such that the first portion  30  is moved sufficiently out of the way so that the umbilical can be easily directed into the target area, which is adjacent the inner surface of the second portion  32 . See  FIG. 7 . 
     In the depicted embodiment the umbilical interface actuation assembly  28  includes a frame mount  34  that supports a normally locked pivot connection  36  between the frame mount  34  and the second portion  32  of the clam shell portion  26 , and a driven pivot connection  38  between the frame mount  34  and the first portion  30 . The driven pivot connection  38  includes a hydraulic actuated device  40  that rotates the first portion  30  of the clam shell portion  26  relative to the second portion  32  of the clam shell portion  26 . When the driven pivot connection  38  is rotated it engages locking pins that retain the first portion  30  to the second portion  32  so that continuous hydraulic pressure is not needed to keep the clam shell portion  26  closed. The normally locked pivot connection  36  is configured to normally be locked to prevent movement of the second portion  32 , and configured to be mechanically unlocked to allow for movement of the second portion  32 . Direct manual movement of the second portion  32  may be desirable in the event of a malfunction of the driven pivot connection  38  or actuation assembly  28 . 
     In the depicted embodiment the umbilical interface actuation assembly  28  is driven by hydraulic fluid. In the depicted embodiment a hydraulic connection  42  is provided on a side surface of the frame assembly  24 . The hydraulic connection  42  is configured such that a remotely operated vehicle can remove a plug from the hydraulic connection and temporarily store (park) the plug on a holding structure  44  on the frame assembly  24 . Once the plug is removed, a hydraulic line can be provided by the remotely operated vehicle and can be directly connected to the hydraulic connection  42 . 
     Referring to  FIG. 8  the clam shell portion  26  of the umbilical interface  20  is described in greater detail. In the depicted embodiment the geometry of the clam shell portion  26  is configured to prevent damage to the umbilical due to bending, compression or excessive wear. In the depicted embodiment the inner surface forms a sleeve having a generally cylindrical outer shape and a pair of tapered wear inserts  46 ,  48  that are define its inner shape. In the depicted embodiment the wear inserts are tapered from both ends towards a central region. The minimum distance Dmin between the wear inserts  46 ,  48  is slightly larger than the maximum exterior diameter of the umbilical (e.g., the maximum exterior diameter of the umbilical could be 3.5 inches and the Dmin could be 3.8 inches). 
     In the depicted embodiment the cross-sectional profile of the wear inserts  46 ,  48  define a smooth curve wherein at least a portion of the curve has a radius of curvature that is greater than or equal to the minimum recommended radius of curvature for the umbilical. In the depicted embodiment the central portion Cp of the wear inserts has a radius of curvature Rc between 50-60 inches. This configuration prevents contact between the guide assembly and the umbilical from causing the umbilical to bend beyond its minimum recommended radius of curvature (e.g., a minimum recommended radius of curvature of 40 inches). In the depicted embodiment the entire cross-sectional profile includes a constant radius of curvature. Many alternative embodiments are also possible including embodiment with cross-sectional profiles defined by multiple curves. For example,  FIG. 13  depicts one alternative embodiment wherein the cross-sectional profile includes two adjacent curves that each have a radius of curvature Rcc that is greater than or equal to the minimum recommended bend radius of the umbilical. In the depicted embodiment both curves have the same radius of curvature and the radius of curvatures are approximately 42 inches. 
     It should be appreciated that many other alternative configurations for the umbilical interface exists. 
     Referring to  FIG. 9 , an alternative embodiment of the umbilical guide assembly of  FIG. 2  is shown. The umbilical guide assembly  50  is similar to the umbilical guide assembly  10 . The riser interface assembly  52  of the umbilical guide assembly  50  is configured to mount to a shaft portion of the riser  12  rather than the flange located between riser sections. Like the umbilical guide assembly  10 , the umbilical guide assembly  50  is also configured such that it can be installed using a remotely operated vehicle prior to the riser being deployed and secured to the sea floor. This configuration allows for added flexibility with respect to where the guide assembly  50  can be located vertically along the riser. However, it should be appreciated that the umbilical guide assemblies are configured such that they could also be mounted to the riser prior to or during deployment of the riser either manually or via ROV. 
     Referring to  FIGS. 10-12 , a method of securing an umbilical to a riser using the umbilical guide assembly is described in further detail. In the depicted embodiment the umbilical guide assembly  10  is shown being connected to the riser  12  with a remotely operated vehicle  60  while the riser  12  is underwater. In particular,  FIG. 10  depicts a remotely operated vehicle  60  transporting the guide assembly  10  to the riser and aligning it with a portion of a riser flange located between adjacent sections of the riser  12 . It should be appreciated that in other embodiments, including the embodiment shown in  FIG. 9 , the guide assembly can be connected to portions of the riser other than the flange area (e.g., main body or auxiliary lines of the riser). In the depicted embodiment after the guide assembly  10  is connected to the riser, the remotely operated vehicle locates the umbilical and transports the umbilical to the guide assembly. In the depicted embodiment the remotely operated vehicle has a curved front shovel portion that is configured to capture the umbilical and enable the remotely operated vehicle to drive the umbilical into place. 
     In the depicted embodiment, the remotely operated vehicle hydraulically connects to the guide assembly and actuates umbilical interface actuation assembly  28  to open the clam shell portion  26 . The remotely operated vehicle  60  maneuvers the umbilical  14  so that a section of the umbilical  14  is adjacent the second portion  32  of the clam shell portion  26  and then closes the clam shell portion  26 , thereby retaining the umbilical  14  therein and limiting the motion of the umbilical  14  in the horizontal plane while still allowing for longitudinal movement of the umbilical relative to the umbilical guide assembly. 
     The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.