(19)

(11)

EP 0 670 951 A1

(12)

(43) Date of publication: 13.09.1995 Bulletin 1995/37 (21) Application number: 94901918.0 (22) Date of filing: 30.11.1993

(51) International Patent Classification (IPC):  E21B 47/ 022( . ) (86) International application number: PCT/EP1993/003353 (87) International publication number: WO 1994/013931 (23.06.1994 Gazette 1994/14)

(84) Designated Contracting States: BE CH ES FR GR LI (30) Priority: 04.12.1992 IT 1992MI02777 (71) Applicant: VIANINI, Matteo I-37013 Caprino Veronese (IT)	(72) Inventor: VIANINI, Matteo I-37013 Caprino Veronese (IT) (74) Representative: Gervasi, Gemma, Dr., et al  Studio Brevetti e Marchi NOTARBARTOLO & GERVASI S.r.l. 33, Viale Bianca Maria I-20122 Milano I-20122 Milano (IT)