Jack-up rig and method of installing the same on location of operation

Abstract

A system and method for accommodating normal, or larger than normal, support footings for the legs of an offshore jack-up rig, with the support footings now to be known as spud cans, and an improved hull design to accommodate legs with attachable spud cans, along with a method of mounting said spud cans by submerging them, lowering each jack-up leg down on the designated spud can and locking the two units in together.

What is claimed is: 
     
         1 . A jack-up rig comprising:
 a main buoyant hull,   three or more leg wells through said hull,   a jack-up leg in each of the leg wells, the jack-up legs movably coupled to said hull;   each of said leg wells surrounding said legs are formed by one or more walls, and   said walls are substantially vertically straight.   
     
     
         2 . The jack-up rig according to  claim 1 , further comprising a jacking drive system, wherein said jack-up legs are mounted so as to be individually lowered or raised by the jacking drive system, the jacking drive system attached to the main hull to facilitate movement of the jack-up legs vertically through the hull. 
     
     
         3 . The jack-up rig according to  claim 1 , further comprising a jacking drive system, wherein said jack-up legs are mounted in each leg well so as to be lowered or raised by the jacking drive system attached to the hull,
 said jacking drive system comprising:
 a leg driving structure for driving said jack-up legs vertically up and down relative to the main hull, 
 a support structure on which the leg driving structure is installed, and 
 a leg guide structure for guiding the movement of the jack-up legs and providing structural support of said legs, 
 wherein at least part of the leg guide structure is mounted close to the bottom of the hull. 
   
     
     
         4 . The jack-up rig according to  claim 3 , wherein:
 the leg driving structure comprises jacking gears; and   the leg guide structure comprises guide rails.   
     
     
         5 . The jack-up rig according to  claim 3 , wherein at least part of the leg guide structure is mounted within 10 m to the bottom of the hull. 
     
     
         6 . The jack-up rig according to  claim 3 , wherein at least part of the leg guide structure is mounted within 7 m to the bottom of the hull. 
     
     
         7 . The jack-up rig according to  claim 3 , wherein at least part of the leg guide structure is mounted within 6 m to the bottom of the hull. 
     
     
         8 . The jack-up rig according to  claim 3 , wherein at least part of the leg guide structure is mounted within 4 m to the bottom of the hull. 
     
     
         9 . The jack-up rig according to  claim 3 , wherein at least part of the leg guide structure is mounted within 3 m to the bottom of the hull. 
     
     
         10 . The jack-up rig according to  claim 3 , wherein at least part of the leg guide structure is mounted within 2 m to the bottom of the hull. 
     
     
         11 . The jack-up rig according to  claim 3 , wherein at least part of the leg guide structure is mounted within 1 m to the bottom of the hull. 
     
     
         12 . The jack-up rig according to  claim 1 , further comprising separate spud cans attached to the lower end of each jack-up leg. 
     
     
         13 . The jack-up rig according to  claim 1 , further comprising a coupling interface system allowing the coupling of a spud can and a jack-up leg. 
     
     
         14 . The jack-up rig according  claim 13 , wherein the coupling interface system is remotely operated. 
     
     
         15 . The jack-up rig according  claim 13 , wherein the coupling interface system is remotely operated from the main control room of the jack-up rig or from a same location as the jack-up legs are operated. 
     
     
         16 . The jack-up rig according to  claim 12 , wherein said spud can comprises a system to adjust buoyancy. 
     
     
         17 . A method of operating a jack-up rig comprising a main buoyant hull, three or more leg wells through said hull, a jack-up leg in each of the leg wells, the jack-up legs movably coupled to said hull, the method comprising:
 submerging a spud can for each leg to a position accessible to the jack-up rig,   allowing a jack-up leg to be directly attached to said spud can,   floating the jack-up rig (e.g. on its main buoyant hull) and moving it into position so that the jack-up leg is located directly above the spud can, and   connecting the leg with the spud can by lowering the leg through the leg wells in the hull and/or hoisting the spud cans up onto the leg.   
     
     
         18 . The method according to  claim 17 , wherein the jack-up rig is floating on its main buoyant hull. 
     
     
         19 . The method of  claim 17 , further comprising raising the jack-up legs with attached spud cans to a level where the spud cans have clearance, transporting the jack-up rig to a site of operation for which the spud cans have been designed, installing the jack-up rig by lowering the spud cans to the seabed, and operating the jack-up. 
     
     
         20 . The method of  claim 17 , further comprising raising the jack-up legs with attached spud cans to a level where the spud cans have clearance immediately below the main hull, transporting the jack-up rig to a site of operation for which the spud cans have been designed, installing the jack-up rig by lowering the spud cans to the seabed, and operating the jack-up. 
     
     
         21 . The method of  claim 17 , where the method is performed on the location of an operation of the jack-up rig. 
     
     
         22 . The method of  claim 17 , where all spud cans are lowered to the sea floor, aligned to the jack-up rig, and the jack-up legs are lowered down onto the spud cans and connected. 
     
     
         23 . The method of  claim 17 , where one spud can is lowered to the sea floor at a time, the jack-up rig moved into place and aligned to the spud can, and the leg lowered to and fastened to the spud can. 
     
     
         24 . The method of  claim 17 , where the spud cans are lowered to the sea floor, the jack-up rig moved into place and aligned to the spud can and the leg lowered into the sea, but not all the way to the sea floor, and the spud can is hoisted from the sea floor up onto the legs and fastened.