(19)

(11)

EP 0 692 064 A1

(12)

(43) Date of publication: 17.01.1996 Bulletin 1996/03 (21) Application number: 94909945.0 (22) Date of filing: 17.03.1994

(51) International Patent Classification (IPC):  E21B 19/ 14( . ) (86) International application number: PCT/FI1994/000100 (87) International publication number: WO 1994/024410 (27.10.1994 Gazette 1994/24)

(84) Designated Contracting States: AT CH DE FR GB IT LI SE (30) Priority: 08.04.1993 FI 19930001616 (71) Applicant: TAMROCK OY SF-33330 Tampere (FI)	(72) Inventor: LAUNIEMI, Markku FIN-33200 Tampere (FI) (74) Representative: Brunner, Michael John  GILL JENNINGS & EVERY Broadgate House 7 Eldon Street London EC2M 7LH London EC2M 7LH (GB)