(19)

(11)

EP 1 951 988 A2

(12)

(88) Date of publication A3: 26.07.2007 (43) Date of publication: 06.08.2008 Bulletin 2008/32 (21) Application number: 06808669.3 (22) Date of filing: 24.11.2006

(51) International Patent Classification (IPC):  E21B 21/10(2006.01) E21B 41/00(2006.01) E21B 34/14(2006.01) (86) International application number: PCT/GB2006/004400 (87) International publication number: WO 2007/060449 (31.05.2007 Gazette 2007/22)

(84) Designated Contracting States: AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC NL PL PT RO SE SI SK TR (30) Priority: 24.11.2005 GB 0523841 13.04.2006 GB 0607412 (71) Applicant: Churchill Drilling Tools Limited Aberdeen AB10 6XL (GB)	(72) Inventor: CHURCHILL, Andrew, Philip Aberdeen AB10 6XL (GB) (74) Representative: Shanks, Andrew et al Marks & Clerk 19 Royal Exchange Square Glasgow G1 3AE Glasgow G1 3AE (GB)