(19)

(11)

EP 0 083 366 A1

(12)

(43) Date of publication: 13.07.1983 Bulletin 1983/28 (21) Application number: 82902396.0 (22) Date of filing: 25.06.1982

(51) International Patent Classification (IPC):  E21B 43/ 12( . ) F04B 47/ 02( . ) E21B 47/ 00( . ) (86) International application number: PCT/US1982/000859 (87) International publication number: WO 1983/000203 (20.01.1983 Gazette 1983/02)

(84) Designated Contracting States: AT BE CH DE FR GB LI LU NL SE (30) Priority: 26.06.1981 US 19810277727 18.06.1982 US 19820389601 18.06.1982 US 19820389602 (71) Applicants: BASOLO, Domenith Clarence Hillsborough, CA 94101 (US) OLIVER, Stuart McCornack Oxnard, CA 93030 (US) PARSONS, Sanford Jennings Richmond, CA 94805 (US)	(72) Inventors: BASOLO, Domenith Clarence Hillsborough, CA 94101 (US) OLIVER, Stuart McCornack Oxnard, CA 93030 (US) PARSONS, Sanford Jennings Richmond, CA 94805 (US) (74) Representative: Alexander, Thomas Bruce  Boult, Wade & Tennant 27 Furnival Street London EC4A 1PQ London EC4A 1PQ (GB)