(19)

(11)

EP 1 534 923 A1

(12)

(43) Date of publication: 01.06.2005 Bulletin 2005/22 (21) Application number: 03761690.1 (22) Date of filing: 27.06.2003

(51) International Patent Classification (IPC)7: E21B 43/017 (86) International application number: PCT/GB2003/002767 (87) International publication number: WO 2004/003339 (08.01.2004 Gazette 2004/02)

(84) Designated Contracting States: AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PT RO SE SI SK TR Designated Extension States: AL LT LV MK (30) Priority: 28.06.2002 GB 0215064 (71) Applicant: ALPHA THAMES LTD Upminster,Essex RM14 2SU (GB)	(72) Inventors: APPLEFORD, David Eric Epping,Essex CM16 7JD (GB) LANE, Brian William Canvey Island,Essex SS8 8NF (GB) (74) Representative: Johnstone, Douglas Ian et al Baron & Warren,19 South End,Kensington London W8 5BU London W8 5BU (GB)