(19)

(11)

EP 0 864 031 A1

(12)

(43) Date of publication: 16.09.1998 Bulletin 1998/38 (21) Application number: 97909875.0 (22) Date of filing: 25.09.1997

(51) International Patent Classification (IPC):  E21B 19/ 00( . ) E21B 19/ 22( . ) E21B 19/ 09( . ) E21B 33/ 076( . ) (86) International application number: PCT/US1997/017219 (87) International publication number: WO 1998/014686 (09.04.1998 Gazette 1998/14)

(84) Designated Contracting States: BE DE FR GB IT NL (30) Priority: 02.10.1996 US 19960027140P 26.03.1997 US 19970825000 14.08.1997 US 19970911787 (71) Applicant: BAKER HUGHES INCORPORATED Houston Texas 77027 (US)	(72) Inventors: FONTANA, Peter Houston, TX 77005 (US) BURGE, Philip NL-2596 TE The Hague (NL) (74) Representative: Finck, Dieter, Dr.Ing., et al  Patentanwälte v. Füner, Ebbinghaus, Finck Mariahilfplatz 2 - 3 81541 München 81541 München (DE)