(19)

(11)

EP 0 400 037 A1

(12)

(43) Date of publication: 05.12.1990 Bulletin 1990/49 (21) Application number: 89902155.0 (22) Date of filing: 24.01.1989

(51) International Patent Classification (IPC):  E21B 23/ 03( . ) (86) International application number: PCT/US1989/000295 (87) International publication number: WO 1989/007189 (10.08.1989 Gazette 1989/18)

(84) Designated Contracting States: DE FR GB (30) Priority: 03.02.1988 US 19880151654 (71) Applicant: CRAWFORD, William B. Houston, TX 77069 (US)	(72) Inventors: CRAWFORD, William, B. Houston, TX 77069 (US) DE CUIR, Perry, J., Sr. New Iberia, LA 70561-0721 (US) (74) Representative: Allen, William Guy Fairfax  J.A. KEMP & CO. 14 South Square Gray's Inn London WC1R 5LX London WC1R 5LX (GB)