(19)

(11)

EP 1 088 151 A1

(12)

(43) Date of publication: 04.04.2001 Bulletin 2001/14 (21) Application number: 99936456.5 (22) Date of filing: 09.06.1999

(51) International Patent Classification (IPC)7: E21B 29/06, E21B 27/00, E21B 7/28, E21B 4/16 (86) International application number: PCT/EP9904/039 (87) International publication number: WO 9964/715 (16.12.1999 Gazette 1999/50)

(84) Designated Contracting States: DE DK ES GB IT NL (30) Priority: 10.06.1998 EP 98304595 (71) Applicant: SHELL INTERNATIONALE RESEARCHMAATSCHAPPIJ B.V. 2596 HR Den Haag (NL)	(72) Inventors: AMORY, Marc, Emmanuel NL-2288 GD Rijswijk (NL) FISHER, Simon, Lawrence NL-2288 GD Rijswijk (NL) POINTING, Michael, Edward NL-2288 GD Rijswijk (NL) WILLEMSE, Onno NL-2288 GD Rijswijk (NL) ANDERSON, Mark, Wilson NL-2288 GD Rijswijk (NL)