Drilling system and method

1. Drilling system for drilling a well, the drilling system having a well centre through which a drill string may be run into and pulled out of the well, said drilling system comprising:

a coilable drill string;

a first reel for storing said coilable drill string;

a drive means for driving said coilable drill string into the well from said first reel and out of the well to said first reel;

a deflection means for directing said coilable drill string between said first reel and into said well centre;

a top drive;

wherein said coilable drill string is provided with:

a first connection at a first end thereof for connecting the coilable drill string to a bottom-hole-assembly; and

a second connection at a second end thereof for directly connecting the coilable drill string to said top drive.

2. Drilling system according to claim 1 , wherein said coilable drill string comprises a composite material.

3. Drilling system according to claim 1 , wherein said coilable drill string comprises metal.

4. Drilling system according to claim 1 wherein said deflection means is slidable to and from said well centre.

5. Drilling system according to claim 1 , wherein said drilling system further comprises a second reel for storing a second coilable drill string.

6. Drilling system according to claim 1 , wherein said first reel has a diameter in the range 10-15 metres.

7. Drilling system according to claim 1 , wherein said drilling system further comprises a cooling means for cooling said coilable drill string at or near said deflection means.

8. Drilling rig comprising a drilling system according to claim 1 .

9. Method for operating a drilling system according to claim 1 , said method including the steps of:

placing said first reel and said deflection means in an operating position;

connecting said first end of the coilable drill string to said bottom-hole-assembly;

spooling out said coilable drill string from the first reel for lowering said bottom-hole-assembly into the well;

reaching a target depth;

securing said coilable drill sting in said well centre;

disconnecting said first reel from said second end of the coilable drill string; and

connecting said top drive to said second end of the coilable drill string.

10. Method according to claim 9 , wherein the step of connecting said top drive to said second end includes the sub-steps of:

presenting a stand to the well centre and connecting said stand, directly or indirectly, to said second end of the coilable drill string; and

latching said top drive to the stand.

11. Method according to claim 9 , wherein the step disconnecting said first reel from said second end of the coilable drill string includes the step of rotating the coilable drill string on a well-side of the coilable drill string, while keeping said coilable drill string substantially fixed on a reel side of the coilable drill string.

12. Method according to claim 9 , wherein the method further comprises the step of drilling the well by rotating said coilable drill string with the top drive.

13. Drilling system according to claim 1 , wherein said drilling system further comprises a lubrication means for lubricating said coilable drill string at or near said deflection means.

14. Drilling system for drilling a well, the drilling system having a well centre through which a drill string may be run into and pulled out of the well, said drilling system comprising:

a coilable drill string;

a first reel for storing said coilable drill string;

a drive means for driving said coilable drill string into the well from said first reel and out of the well to said first reel;

a deflection means for directing said coilable drill string between said firsts reel and into said well centre;

a top drive;

wherein said coilable drill is provided with:

a first connection at a first end thereof for connecting the coilable drill string to a bottom-hole-assembly; and

a second connection to a second end thereof for connecting the coilable drill string to said top drive, wherein said coilable drill string comprises a plurality of connected drill pipes.

15. Drilling system according to claim 14 , wherein said first reel comprises recesses configured to accommodate joints between the connected pipes, said joints having a larger diameter than said drill pipes.

16. Drilling system for drilling a well, the drilling system having a well centre through which a drill string may be run into and pulled out of the well, said drilling system comprising:

a coilable drill string;

a first reel for storing said coilable drill string;

a drive means for driving said coilable drill string into the well from said first reel and out of the well to said first reel;

a deflection means for directing said coilable drill string between said first reel and into said well centre;

a top drive;

wherein said coilable drill is provided with:

a first connection at a first end thereof for connecting the coilable drill string to a bottom-hole-assembly; and

a second connection to a second end thereof for connecting the coilable drill string to said top drive, wherein said top drive is connectable to said second end of the coilable drill string via a drill stand.