(19)

(11)

EP 0 682 739 A1

(12)

(43) Date of publication: 22.11.1995 Bulletin 1995/47 (21) Application number: 93911936.0 (22) Date of filing: 10.05.1993

(51) International Patent Classification (IPC):  E21B 3/ 02( . ) E21B 33/ 072( . ) (86) International application number: PCT/GB1993/000964 (87) International publication number: WO 1993/023654 (25.11.1993 Gazette 1993/28)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB GR IE IT LI LU MC NL PT SE (30) Priority: 09.05.1992 GB 19920010059 (71) Applicant: MACKINTOSH, Kenneth Aberdeen AB1 4HD (GB)	(72) Inventor: MACKINTOSH, Kenneth Aberdeen AB1 4HD (GB) (74) Representative: McCallum, Graeme David, et al  Murgitroyd & Company, Chartered Patent Agents, 373 Scotland Street Glasgow G5 8QA Glasgow G5 8QA (GB)