(19)

(11)

EP 1 404 944 A2

(12)

(88) Date of publication A3: 03.01.2003 (43) Date of publication: 07.04.2004 Bulletin 2004/15 (21) Application number: 02738305.8 (22) Date of filing: 14.05.2002

(51) International Patent Classification (IPC)7: E21B 43/01 (86) International application number: PCT/GB2002/002217 (87) International publication number: WO 2002/092961 (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 0112103 (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  Baron & Warren,19 South End Kensington,London W8 5BU Kensington,London W8 5BU (GB)