(19)

(11)

EP 0 752 049 A1

(12)

(43) Date of publication: 08.01.1997 Bulletin 1997/02 (21) Application number: 95930623.0 (22) Date of filing: 04.09.1995

(51) International Patent Classification (IPC):  E21B 43/ 12( . ) (86) International application number: PCT/GB1995/002079 (87) International publication number: WO 1996/007813 (14.03.1996 Gazette 1996/12)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB GR IE IT LI LU MC NL PT SE (30) Priority: 07.09.1994 US 19940301661 02.05.1995 US 19950434037 (71) Applicant: HALLIBURTON COMPANY Dallas, Texas 75381-9052 (US)	(72) Inventor: SCHMIDT, Zelimir Tulsa, OK 74136 (US) (74) Representative: Wain, Christopher Paul, et al  A.A. THORNTON & CO. Northumberland House 303-306 High Holborn London WC1V 7LE London WC1V 7LE (GB)