(19)

(11)

EP 0 996 810 A1

(12)

(43) Date of publication: 03.05.2000 Bulletin 2000/18 (21) Application number: 98935684.5 (22) Date of filing: 17.07.1998

(51) International Patent Classification (IPC)7: E21B 10/66 (86) International application number: PCT/US9814/651 (87) International publication number: WO 9904/130 (28.01.1999 Gazette 1999/04)

(84) Designated Contracting States: DE ES FI GB IT SE (30) Priority: 18.07.1997 US 896787 (71) Applicant: Holte, Ardis L. Eugene, OR 97402 (US)	(72) Inventor: Holte, Ardis L. Eugene, OR 97402 (US) (74) Representative: Weatherald, Keith Baynes  Castles,17 Lansdowne Road Croydon,Surrey CR0 2BX Croydon,Surrey CR0 2BX (GB)