(19)

(11)

EP 0 757 746 A1

(12)

(43) Date of publication: 12.02.1997 Bulletin 1997/07 (21) Application number: 93909291.0 (22) Date of filing: 09.04.1993

(51) International Patent Classification (IPC):  E21B 49/ 00( . ) (86) International application number: PCT/US1993/003321 (87) International publication number: WO 1993/021420 (28.10.1993 Gazette 1993/26)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB GR IE IT LI LU MC NL PT SE (30) Priority: 09.04.1992 US 19920865462 (71) Applicant: Amen, Randall M. Estes Park, Colorado 80517 (US)	(72) Inventor: Amen, Randall M. Estes Park, Colorado 80517 (US) (74) Representative: Bowman, Paul Alan  LLOYD WISE, TREGEAR & CO., Commonwealth House, 1-19 New Oxford Street London WC1A 1LW London WC1A 1LW (GB)