Offshore coiled tubing system

Abstract

The present invention relates to an offshore coiled tubing system for running a coiled tubing into a subsea well offshore, comprising a well comprising a well tubular metal structure having a top and an inner face, a blowout preventer (BOP) arranged in the top of the well tubular metal structure, and a sluice having a top part for entry of coiled tubing, the BOP being arranged between the well tubular metal structure and the sluice, the sluice having a sealing unit arranged in the top part of the sluice for sealing around the coiled tubing, a vessel comprising a deck, a coiled tubing reel comprising coiled tubing, the coiled tubing having a first end, and a first driving unit for assisting in driving the coiled tubing into/from the well, the first driving unit being configured to be movable in relation to the deck to compensate for heave motion of the vessel, and a second driving unit for assisting in driving the coiled tubing into/from the well, wherein the second driving unit is movable in relation to the BOP. The present invention also relates to an offshore coiled tubing method.

1 . An offshore coiled tubing system for running a coiled tubing into a subsea well offshore, comprising:
 a well comprising:
 a well tubular metal structure having a top and an inner face, 
 a blowout preventer arranged in the top of the well tubular metal structure, and 
 a sluice having a top part for entry of coiled tubing, the blowout preventer being arranged between the well tubular metal structure and the sluice, the sluice having a sealing unit arranged in the top part of the sluice for sealing around the coiled tubing, 
   a vessel comprising:
 a deck, 
 a coiled tubing reel comprising coiled tubing, the coiled tubing having a first end, and 
 a first driving unit for assisting in driving the coiled tubing into/from the well, the first driving unit being configured to be movable in relation to the deck to compensate for heave motion of the vessel, and 
   a second driving unit for assisting in driving the coiled tubing into/from the well,   wherein the second driving unit is movable in relation to the blowout preventer.   
     
     
         2 . An offshore coiled tubing system according to  claim 1 , wherein the second driving unit is connected to the first end of the coiled tubing. 
     
     
         3 . An offshore coiled tubing system according to  claim 1 , wherein the second driving unit is configured to be moved into the well tubular metal structure together with the coiled tubing. 
     
     
         4 . An offshore coiled tubing system according to  claim 1 , wherein the second driving unit comprises several projectable parts configured to engage the inner face of the well tubular metal structure. 
     
     
         5 . An offshore coiled tubing system according to  claim 4 , wherein the projectable parts each comprises a wheel on an arm, and each wheel comprises a motor, such as a hydraulic or electrical motor. 
     
     
         6 . An offshore coiled tubing system according to  claim 5 , wherein the arm is projectable by means of pressurised fluid. 
     
     
         7 . An offshore coiled tubing system according to  claim 1 , wherein the first driving unit is configured to drive the coiled tubing by engaging an outer face of the coiled tubing, and the second driving unit is configured to drive the coiled tubing by engaging the inner face of the well tubular metal structure. 
     
     
         8 . An offshore coiled tubing system according to  claim 7 , wherein the second driving unit is configured to provide a tension in the coiled tubing. 
     
     
         9 . An offshore coiled tubing system according to  claim 1 , wherein the sluice is a riser or a lubricator. 
     
     
         10 . An offshore coiled tubing system according to  claim 1 , wherein the sealing unit is a stripper. 
     
     
         11 . An offshore coiled tubing method for running a coiled tubing into a well offshore, comprising:
 positioning a vessel of an offshore coiled tubing system according to any of the preceding claims above a well,   connecting the second driving unit to the first end of the coiled tubing,   introducing the second driving unit and part of the coiled tubing into the sluice,   pressurising the sluice for providing a pressure inside the sluice, said pressure being substantially equal to a pressure in the well tubular metal structure, and   driving the coiled tubing into the well tubular metal structure by means of the second driving unit.   
     
     
         12 . An offshore coiled tubing method according to  claim 11 , wherein the driving of the coiled tubing into the well tubular metal structure by means of the second driving unit is performed by moving the second driving unit together with the coiled tubing into the well tubular metal structure. 
     
     
         13 . An offshore coiled tubing method according to  claim 11 , wherein the driving of the coiled tubing into the well tubular metal structure by means of the second driving unit is performed by providing the second driving unit with several projectable parts configured to engage the inner face of the well tubular metal structure. 
     
     
         14 . An offshore coiled tubing method according to  claim 11 , wherein the step of driving the coiled tubing into the well tubular metal structure by means of the second driving unit comprises adjusting the speed according to a predetermined tension in the coiled tubing. 
     
     
         15 . An offshore coiled tubing method according to  claim 11 , wherein the step of driving the coiled tubing into the well tubular metal structure by means of the second driving unit comprises pulling the coiled tubing forward in the well.