(19)

(11)

EP 2 176 506 A2

(12)

(88) Date of publication A3: 22.05.2009 (43) Date of publication: 21.04.2010 Bulletin 2010/16 (21) Application number: 08788333.6 (22) Date of filing: 15.08.2008

(51) International Patent Classification (IPC):  E21B 19/00(2006.01) E21B 19/24(2006.01) (86) International application number: PCT/GB2008/002764 (87) International publication number: WO 2009/024760 (26.02.2009 Gazette 2009/09)

(84) Designated Contracting States: AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MT NL NO PL PT RO SE SI SK TR Designated Extension States: AL BA MK RS (30) Priority: 17.08.2007 GB 0716130 17.08.2007 US 935528 P (71) Applicant: Grenland Group Technology As 3202 Sandefjord (NO)	(72) Inventor: SORENSON, Bjorn Bro N-3215 Sandefjord (NO) (74) Representative: Piésold, Alexander James  Dehns St Bride's House 10 Salisbury Square London EC4Y 8JD London EC4Y 8JD (GB)