(19)

(11)

EP 1 392 955 A1

(12)

(43) Date of publication: 03.03.2004 Bulletin 2004/10 (21) Application number: 02769513.9 (22) Date of filing: 14.05.2002

(51) International Patent Classification (IPC)7: E21B 43/36, E21B 43/12, E21B 43/34 (86) International application number: PCT/GB2002/002255 (87) International publication number: WO 2002/092965 (21.11.2002 Gazette 2002/47)

(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: 17.05.2001 GB 0112107 (71) Applicant: Alpha Thames Limited Upminster,Essex RM14 2SU (GB)	(72) Inventors: APPLEFORD, David, Eric Epping,Essex CM16 7JD (GB) LANE, Brian, William Essex SS8 8NF (GB) (74) Representative: Johnstone, Douglas Ian et al Baron & Warren,19 South End Kensington,London W8 5BU Kensington,London W8 5BU (GB)