Drilling Unit Comprising an Electric Heave-Compensation System

Abstract

A drilling unit on a deck of a floating vessel, includes a drill tower structure with a heave-compensation system, a winch mounted at or near the deck, a crown block mounted at a top side of the drill tower structure and at least one wire rope between the winch and the crown block. The heave-compensation system includes a slideable support frame configured to be moved in a direction substantially parallel to the axial direction of the drill tower structure. Either the winch or the crown block is positioned within the slideable support frame such that a distance between the winch and the crown block is controlled by at least one electric motor or linear actuator. In an alternative embodiment in which a crown block in not employed, the winch is placed in the slideable support frame at the top side of the drill tower structure.

1 . Drilling unit for mounting on a deck of a floating vessel, the drilling unit comprising:
 a drill tower structure with a heave-compensation system for compensating vertical movements of the floating vessel due to waves, wherein the drilling unit further comprises:
 a winch, 
 a crown block mounted at a top side of the drill tower structure and 
 at least one wire rope provided between the winch and the crown block, 
   wherein the heave-compensation system comprises a slideable support frame configured to be moved relative to the drill tower structure in a direction substantially parallel to the axial direction of the drill tower structure, and   wherein either the winch or the crown block is provided within the slideable support frame such that a distance between the winch and the crown block is controllable, and   wherein the position of the slideable support frame with respect to the drill tower structure is controlled by at least one electric motor or linear actuator.   
     
     
         2 . The drilling unit according to  claim 1 , wherein the slideable support frame is provided with at least one friction track, and wherein the drill tower structure is provided with at least one rotatable friction wheel that is driven by the at least one electric motor or linear actuator, the at least one rotatable friction wheel being configured for rolling over the at least one friction track for controlling the position of the slideable support frame. 
     
     
         3 . The drilling unit according to  claim 1 , wherein the drill tower structure is provided with at least one friction track, and wherein the slideable support frame is provided with at least one rotatable friction wheel that is driven by the at least one electric motor or linear actuator, the at least one rotatable friction wheel being configured for rolling over the at least one friction track for controlling the position of the slideable support frame. 
     
     
         4 . The drilling unit according to  claim 2 , wherein the at least one friction wheel is directly driven by the at least one electric motor or linear actuator. 
     
     
         5 . The drilling unit according to  claim 2 , comprising one or more respective gearing systems in between the at least one electric motor or linear actuator and the at least one friction wheel. 
     
     
         6 . The drilling unit according to any one of  claims 2 , wherein the at least one friction track comprises a toothed rack. 
     
     
         7 . The drilling unit according to any one of  claims 2 , wherein the at least one rotatable friction wheel comprises a pinion. 
     
     
         8 . The drilling unit according to  claim 1 , wherein the winch is also configured for compensating vertical movements of the floating vessel due to waves. 
     
     
         9 . The drilling unit according to  claim 1 , further comprising an energy recovery system connected to the at least one electric motor or linear actuator, wherein the energy recovery system is configured for storing energy generated by a load when the load is being lowered and for supplying it to the at least one electric motor or linear actuator when the load is being hoisted. 
     
     
         10 . The drilling unit according to  claim 1  wherein the winch is provided within the slideable support frame. 
     
     
         11 . The drilling unit according to  claim 1 , wherein the crown block provided within the slideable support frame. 
     
     
         12 . The drilling unit according to  claim 1 , wherein the winch located at a drill floor or deck ( 200 ). 
     
     
         13 . The drilling unit according to  claim 1 , wherein the winch is located outside the drill tower structure ( 130 ). 
     
     
         14 . The drilling unit according to  claim 1 , wherein the winch is located inside the drill tower structure ( 130 ). 
     
     
         15 . The drilling unit according to  claim 1 , wherein the slideable support frame is configured for being lockable relative the drill tower structure. 
     
     
         16 . Drilling unit for mounting on a deck of a floating vessel, the drilling unit comprising:
 a drill tower structure with a heave-compensation system for compensating vertical movements of the floating vessel due to waves,   wherein the drilling unit further comprises a winch and at least one wire rope coupled to the winch,   wherein the heave-compensation system comprises a slideable support frame provided at a top side of the drill tower structure, and   wherein the slideable support frame is configured to be moved relative to the drill tower structure in a direction substantially parallel to the axial direction of the drill tower structure, and   wherein the winch is provided within the slideable support frame, and   wherein the position of the slideable support frame with respect to the drill tower structure is controlled by at least one electric motor or linear actuator.