Drill ship for deep sea intervention operations

Abstract

A drill ship is provided for conducting subsea operations, including intervention, maintenance and workover operations. The ship includes a hull having a substantially wide beam-to-length ratio and a deckspace. An automated system for handling tubulars and risers is mounted to the deck space, along with a pipe racking system. The deckspace includes a heavy-lift heave crane for handling seafloor operations and a medium duty crane mounted over the deckspace. The ship is configured to provide heavy lift subsea construction operations including 16-inch riser well intervention and workover programs, connected riser completion operations, and riserless tophole drilling and casing operations. The ship is also able to perform connected riser remedial drilling and slim hole well construction. The ship maximizes environmental efficiency in both construction and use, and provides a stable and safe work and living environment for operations personnel.

1 . A drill ship for conducting subsea operations comprising:
 a hull having a substantially wide beam-to-length ratio and a deckspace;   an automated system for handling tubulars and risers, said system interfacing with a pipe racking arrangement mounted to said deckspace;   a heavy-lift heave crane mounted over said deckspace for handling seafloor operations; and   a medium duty crane mounted over said deckspace.   
     
     
         2 . The drill ship in  claim 1  wherein the hull incorporates a small force hull form to provide low fuel consumption, and
 wherein the hull is nitrogen-blanketed for storage of methanol and helifuel. 
 
     
     
         3 . The drill ship in  claim 1  further comprising at least one exhaust NOx emission reactor. 
     
     
         4 . The drill ship in  claim 1  wherein the hull has a beam-to-length ratio less than three. 
     
     
         5 . The drill ship in  claim 1  further comprising:
 a helipad; and 
 a remote operated vehicle installation. 
 
     
     
         6 . The drill ship in  claim 1  wherein the automated handling system comprises a hinged rig floor. 
     
     
         7 . The drill ship in  claim 1  further comprising a blowout preventer stack. 
     
     
         8 . The drill ship in  claim 7  wherein the blowout prevent stack is a wellconnector, annual ram blowout preventer stack. 
     
     
         9 . The drill ship in  claim 7  wherein the blowout preventer stack comprises:
 a wellhead connector; 
 a double ram blowout preventer unit; 
 an annular preventer; and 
 a lower marine rise package connector. 
 
     
     
         10 . The drill ship in  claim 1  further comprising a box tower hoisting and lowering system with top drive and active heave compensation, the box tower hoisting and lowering system comprising:
 a heave-compensated drawworks; and 
 a segmented traveling block. 
 
     
     
         11 . The drill ship in  claim 10  wherein the heave-compensated drawworks has a 400 metric ton capacity. 
     
     
         12 . The drill ship in  claim 1  wherein the heavy lift crane is a heavy-lift knuckle-boom, seafloor action heave crane. 
     
     
         13 . The drill ship in  claim 12  wherein the heavy-lift crane has a two-hour lowering speed to the rated depth at maximum load. 
     
     
         14 . The drill ship in  claim 1  wherein the medium duty crane is a knuckle-boom deck utility crane. 
     
     
         15 . The drill ship in  claim 14  wherein the medium duty crane comprises a pipe gripper arm. 
     
     
         16 . The drill ship in  claim 1  further comprising:
 a fluid pump; and 
 a cement processor. 
 
     
     
         17 . The drill ship in  claim 1  wherein the cement processor comprises:
 a fluid pump; 
 a choke-and-kill line; 
 a hydraulic supply line; 
 a mud booster/circulating line; and 
 a pup joint. 
 
     
     
         18 . A method of conducting a subsea operation comprising:
 navigating a ship to a location in a body of water, the ship comprising:
 a hull having a substantially wide beam-to-length ratio and a deckspace; 
 an automated system for handling tubulars and risers, said system interfacing with a pipe racking arrangement mounted to said deckspace; 
 a heavy-lift heave crane mounted over said deckspace for handling seafloor operations; and 
 a medium duty crane mounted over said deckspace. 
   
     
     
         19 . The method of  claim 3  further comprising operating the automated system to move a blowout preventer stack. 
     
     
         20 . A drill ship for conducting subsea operations comprising:
 a light displacement hull;   a heavy-lift heave crane;   a medium duty deck crane;   a plurality of fluid pumps;   a plurality of cement units; and   a blowout preventer (BOP) handling system comprising:   a subsea blowout preventer;   a pressurized riser system; and   a box tower hoisting and lowering system with a top drive and an active heave compensated drawworks.