(19)

(11)

EP 0 901 560 A1

(12)

(43) Date of publication: 17.03.1999 Bulletin 1999/11 (21) Application number: 98912587.0 (22) Date of filing: 24.03.1998

(51) International Patent Classification (IPC):  E21B 7/ 04( . ) E21B 17/ 00( . ) E21B 7/ 10( . ) (86) International application number: PCT/GB1998/000739 (87) International publication number: WO 1998/042944 (01.10.1998 Gazette 1998/39)

(84) Designated Contracting States: AT BE DE DK ES FR GB GR IE IT NL PT (30) Priority: 24.03.1997 US 19970069146 (71) Applicant: Sibille, Patrick Neil Aberdeen AB15 4AA (GB)	(72) Inventor: OWENS, Dewey, E. Maurice, LA 70555-3334 (US) (74) Representative: Pattullo, Norman  Murgitroyd and Company 373 Scotland Street Glasgow G5 8QA Glasgow G5 8QA (GB)