Jackup drilling unit having material storage in jacking legs

Abstract

A jackup mobile offshore drilling unit includes a hull and a plurality of jacking legs movable longitudinally with respect to the hull and having features thereon to support the hull above a body of water. A storage tank is disposed inside at least one of the plurality of jacking legs. The unit comprises means for moving the storage tank longitudinally inside the at least one of the plurality of jacking legs.

1 . A jackup mobile offshore drilling unit, comprising:
 a hull;   a plurality of jacking legs movable longitudinally with respect to the hull and having features thereon to support the hull above a body of water;   means for moving the jacking legs;   a storage tank disposed inside at least one of the plurality of jacking legs; and   means for moving the storage tank longitudinally inside the at least one of the plurality of jacking legs, wherein the means for moving the storage tank is synchronized with means for moving the at least one of the jacking legs such that the storage tank is maintained at a substantially constant elevation with respect to the hull.   
     
     
         2 . The jackup mobile offshore drilling unit of  claim 1  wherein the means for moving comprises a winch disposed on the hull, a cable deployed from the winch and at least one sheave disposed proximate an upper end of the at least one of the plurality of jacking legs. 
     
     
         3 . The jackup mobile offshore drilling unit of  claim 1  further comprising a reel disposed on the hull and having thereon at least one fluid transfer hose in fluid communication with an interior of the storage tank. 
     
     
         4 . The jackup mobile offshore drilling unit of  claim 1  further comprising a storage tank disposed inside each of the plurality of jacking legs; and
 means for moving each storage tank longitudinally inside each of the plurality of jacking legs. 
 
     
     
         5 . (canceled) 
     
     
         6 . The jackup mobile offshore drilling unit of  claim 1  wherein the plurality of jacking legs are each shaped as an elongated cylinder. 
     
     
         7 . A method for jacking a jackup mobile offshore drilling unit, comprising:
 operating a jacking motor to move at least one of a plurality of jacking legs longitudinally with respect to a hull of the drilling unit;   operating a means for movably suspending a storage tank disposed inside the at least one of the plurality of jacking legs so as to move the storage tank to a selected elevation with respect to the hull and maintain said selected elevation as the at least one of the jacking legs moves longitudinally.   
     
     
         8 . (canceled) 
     
     
         9 . The method of  claim 7  wherein the selected elevation entirely within a jacking leg opening in the hull. 
     
     
         10 . The method of  claim 9  wherein the selected elevation is such that the storage tank is substantially entirely above a water surface.