(19)

(11)

EP 1 266 120 A1

(12)

(43) Date of publication: 18.12.2002 Bulletin 2002/51 (21) Application number: 01911870.2 (22) Date of filing: 12.03.2001

(51) International Patent Classification (IPC)7: E21B 37/04 (86) International application number: PCT/GB0101/056 (87) International publication number: WO 0106/6907 (13.09.2001 Gazette 2001/37)

(84) Designated Contracting States: AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR Designated Extension States: AL LT LV MK RO SI (30) Priority: 10.03.2000 GB 0005739 19.05.2000 GB 0012008 (71) Applicant: Nortech Systems Limited Aberdeen AB12 3BT (GB)	(72) Inventor: GRAEME, Gordon Aberdeen (GB) (74) Representative: Henderson, Wendy Agnes  Fitzpatricks,4 West Regent Street Glasgow G2 1RS Glasgow G2 1RS (GB)