(19)

(11)

EP 2 516 788 A1

(12)

(43) Date of publication: 31.10.2012 Bulletin 2012/44 (21) Application number: 10798559.0 (22) Date of filing: 22.12.2010

(51) International Patent Classification (IPC):  E21B 7/04(2006.01) E21B 7/00(2006.01) E21B 7/18(2006.01) B24C 9/00(2006.01) (86) International application number: PCT/EP2010/070490 (87) International publication number: WO 2011/076845 (30.06.2011 Gazette 2011/26)

(84) Designated Contracting States: AL 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 RS SE SI SK SM TR (30) Priority: 23.12.2009 EP 09180516 (71) Applicant: Shell Internationale Research Maatschappij B.V. 2596 HR The Hague (NL)	(72) Inventors: BLANGÉ, Jan-Jette NL-2288 GS Rijswijk (NL) VAN NIEUWKOOP, Pieter NL-2288 GS Rijswijk (NL) (74) Representative: Matthezing, Robert Maarten et al Shell International B.V. LSI PO Box 384 2501 CJ The Hague 2501 CJ The Hague (NL)