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EP 1 064 452 A1

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(43) Date of publication: 03.01.2001 Bulletin 2001/01 (21) Application number: 99909756.1 (22) Date of filing: 03.03.1999

(51) International Patent Classification (IPC)7: E21B 49/10, E21B 43/26, E21B 49/06, E21B 33/124, E21B 49/00 (86) International application number: PCT/US9904/596 (87) International publication number: WO 9945/236 (10.09.1999 Gazette 1999/36)

(84) Designated Contracting States: DE FR GB NL (30) Priority: 06.03.1998 US 77144 P 01.06.1998 US 88208 07.01.1999 US 226865 (71) Applicant: BAKER HUGHES INCORPORATED HoustonTexas 77027 (US)	(72) Inventors: BERGER, Per, Erik N-4082 Vestre (NO) REIMERS, Nils N-4005 Stavanger (NO) MACUNE, Don, Thorton Houston, TX 77098 (US) (74) Representative: Jeffrey, Philip Michael et al Frank B. Dehn & Co.179 Queen Victoria Street London EC4V 4EL London EC4V 4EL (GB)