(19)

(11)

EP 0 782 660 A1

(12)

(43) Date of publication: 09.07.1997 Bulletin 1997/28 (21) Application number: 95932810.0 (22) Date of filing: 25.09.1995

(51) International Patent Classification (IPC):  E21B 17/ 10( . ) (86) International application number: PCT/GB1995/002272 (87) International publication number: WO 1996/009459 (28.03.1996 Gazette 1996/14)

(84) Designated Contracting States: DE FR GB IT NL (30) Priority: 24.09.1994 GB 19940019313 14.02.1995 US 19950388603 (71) Applicant: WEATHERFORD/LAMB, INC. Dover, DE 19901 (US)	(72) Inventor: STOKKA, Arnold N-4300 Sandnes (NO) (74) Representative: Lucas, Brian Ronald, et al  Lucas & Co. 135 Westhall Road Warlingham Surrey CR6 9HJ Warlingham Surrey CR6 9HJ (GB)