(19)

(11)

EP 2 427 623 A1

(12)

(43) Date of publication: 14.03.2012 Bulletin 2012/11 (21) Application number: 10772302.5 (22) Date of filing: 29.04.2010

(51) International Patent Classification (IPC):  E21B 7/06(2006.01) E21D 9/10(2006.01) E21B 17/10(2006.01) (86) International application number: PCT/NO2010/000157 (87) International publication number: WO 2010/128861 (11.11.2010 Gazette 2010/45)

(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 MK MT NL NO PL PT RO SE SI SK SM TR (30) Priority: 06.05.2009 NO 20091795 (71) Applicant: Norwegian Hard Rock Drilling AS 4441 Tonstad (NO)	(72) Inventors: HAUGHOM, Sigurd, Kjell 4440 Tonstad (NO) VATLAND, Hans, Are 4440 Tonstad (NO) (74) Representative: Håmsø, Gunnar  Håmsø Patentbyrå ANS P.O. Box 171 4302 Sandnes 4302 Sandnes (NO)