(19)

(11)

EP 0 293 379 A1

(12)

(43) Date of publication: 07.12.1988 Bulletin 1988/49 (21) Application number: 87901157.0 (22) Date of filing: 03.02.1987

(51) International Patent Classification (IPC):  E21B 19/ 14( . ) (86) International application number: PCT/SE1987/000047 (87) International publication number: WO 1987/004754 (13.08.1987 Gazette 1987/18)

(84) Designated Contracting States: AT BE CH DE FR GB IT LI LU NL (30) Priority: 03.02.1986 SE 19860000460 (71) Applicant: Craelius AB S-195 01 Märsta (SE)	(72) Inventor: JONSSON, Gunnar S-183 46 Täby (SE) (74) Representative: Westerlund, Christer, et al  L.A. Groth & Co Patentbyra AB, P.O. Box 6107 S-102 32 Stockholm S-102 32 Stockholm (SE)