(19)

(11)

EP 0 776 410 A1

(12)

(43) Date of publication: 04.06.1997 Bulletin 1997/23 (21) Application number: 95928564.0 (22) Date of filing: 16.08.1995

(51) International Patent Classification (IPC):  E21B 21/ 06( . ) (86) International application number: PCT/GB1995/001936 (87) International publication number: WO 1996/005408 (22.02.1996 Gazette 1996/09)

(84) Designated Contracting States: AT DE DK FR GB IE IT NL (30) Priority: 17.08.1994 GB 19940016586 (71) Applicant: Astleford, John St. Austell, Cornwall PL25 3BN (GB)	(72) Inventor: Astleford, John St. Austell, Cornwall PL25 3BN (GB) (74) Representative: Bryer, Kenneth Robert  K.R. Bryer & Co. Lewins House Lewins Mead Bristol BS1 2NN Bristol BS1 2NN (GB)