(19)

(11)

EP 0 851 960 A1

(12)

(43) Date of publication: 08.07.1998 Bulletin 1998/28 (21) Application number: 95933577.0 (22) Date of filing: 18.09.1995

(51) International Patent Classification (IPC):  E21B 15/ 00( . ) (86) International application number: PCT/IB1995/000901 (87) International publication number: WO 1997/011243 (27.03.1997 Gazette 1997/14)

(84) Designated Contracting States: DE DK FR GB IE IT NL SE (71) Applicant: DRECO, INC. Houston, TX 77236 (US)	(72) Inventor: DESAI, Vinod Houston, TX 77083 (US) (74) Representative: Ede, Eric, et al  Fitzpatricks, 4 West Regent Street Glasgow G2 1RS, Scotland Glasgow G2 1RS, Scotland (GB)