Apparatus and method for seafloor stockpiling

Abstract

An apparatus for seafloor stockpiling that has a slurry inlet that receives slurry from a seafloor tool via a slurry transfer pipe and walls that, together with the seafloor, define a cavity having a stockpiling volume. The walls are made substantially of a water permeable material, such as a filter fabric or geotextile, that captures and contains seafloor material present in slurry received from the slurry inlet, while permitting egress of water from the slurry. In a preferred form the seafloor stockpiling device is a hood with an open bottom that is located on a seafloor surface.

1 . A seafloor stockpiling device that is located on the seafloor in use, the device comprising:
 a slurry inlet for attachment of a slurry transfer pipe and for receiving slurry from a seafloor tool; and   a hood with an open bottom comprising walls that substantially define a cavity having a stockpiling volume, the walls being configured to capture and contain seafloor material present in the slurry in the device while permitting egress of water present in the slurry from the device.   
     
     
         2 . (canceled) 
     
     
         3 . The seafloor stockpiling device of  claim 1 , wherein the walls define the cavity together with a seafloor surface that the seafloor stockpiling device is located on. 
     
     
         4 . The seafloor stockpiling device of  claim 1 , wherein the walls are water permeable. 
     
     
         5 . The seafloor stockpiling device of  claim 1 , wherein at least a portion of the walls comprise a filter material. 
     
     
         6 . The seafloor stockpiling device of  claim 5 , wherein the filter material is reversibly mounted such that reversing the mounting of the filter material causes an inward facing surface of the filter material to become outward facing. 
     
     
         7 . The seafloor stockpiling device of  claim 5 , wherein the filter material is a geotextile. 
     
     
         8 . The seafloor stockpiling device of  claim 1 , wherein at least a portion of the walls comprise a filter structure. 
     
     
         9 . The seafloor stockpiling device of  claim 8 , wherein the filter structure is an inclined plate or tube settler. 
     
     
         10 . The seafloor stockpiling device of  claim 1 , further comprising movable sections that can be moved to between a storage position and a travel position, wherein the drag load during movement of the seafloor stockpiling device is reduced in the travel position. 
     
     
         11 . The seafloor stockpiling device of  claim 1 , further comprising at least one friction reduction mechanism that reduces static friction between the seafloor stockpiling device and the seafloor. 
     
     
         12 . The seafloor stockpiling device of  claim 11 , wherein the friction reduction mechanism comprises one or more fluid outlets adjacent a bottom portion of the seafloor stockpiling device. 
     
     
         13 . The seafloor stockpiling device of  claim 12 , wherein the one or more fluid outlets are fluidly connected via a conduit to a diverter valve in the slurry inlet. 
     
     
         14 . The seafloor stockpiling device of  claim 12 , wherein the one or more fluid outlets are directed generally towards the seafloor. 
     
     
         15 . The seafloor stockpiling device of  claim 12 , wherein the one or more fluid outlets comprise nozzles. 
     
     
         16 . The seafloor stockpiling device of  claim 11 , wherein the friction reduction mechanism comprises movable walls. 
     
     
         17 . The seafloor stockpiling device of  claim 16 , wherein the movable walls are preferably contained inside the walls of the seafloor stockpiling device and enclose seafloor material contained within the device. 
     
     
         18 . The seafloor stockpiling device of  claim 16 , wherein the movable walls pivot relative to the walls of the seafloor stockpiling device. 
     
     
         19 . The seafloor stockpiling device of  claim 1 , further comprising a lifting attachment. 
     
     
         20 . The seafloor stockpiling device of  claim 1 , further comprising an offset lifting attachment that is offset from a central axis of the seafloor stockpiling device. 
     
     
         21 . The seafloor stockpiling device of  claim 20 , wherein the offset lifting attachment is located adjacent an outer edge of the seafloor stockpiling device. 
     
     
         22 . The seafloor stockpiling device of  claim 1 , wherein the seafloor stockpiling device is formed from at least two modules configured for separate deployment from a surface vessel and for underwater interconnection. 
     
     
         23 . The seafloor stockpiling device of  claim 1 , further comprising a stockpile removal device. 
     
     
         24 . The seafloor stockpiling device of  claim 23 , wherein the stockpile removal device comprises an opening port in at least one of the walls of the seafloor stockpiling device. 
     
     
         25 . The seafloor stockpiling device of  claim 1 , wherein the walls are angled forming a substantially frustoconical shape. 
     
     
         26 . The seafloor stockpiling device of  claim 1 , further comprising a rigid skirt around the periphery of the seafloor stockpiling device.