(19)

(11)

EP 0 069 773 A1

(12)

(43) Date of publication: 19.01.1983 Bulletin 1983/03 (21) Application number: 82900713.0 (22) Date of filing: 15.01.1982

(51) International Patent Classification (IPC):  E21B 23/ 08( . ) E21B 37/ 00( . ) E21B 49/ 00( . ) E21B 28/ 00( . ) E21B 47/ 00( . ) G01N 21/ 86( . ) (86) International application number: PCT/US1982/000044 (87) International publication number: WO 1982/002573 (05.08.1982 Gazette 1982/19)

(84) Designated Contracting States: FR (30) Priority: 16.01.1981 US 19810225535 (71) Applicant: GEO-OPTICS LTD. Dallas, TX 75248 (US)	(72) Inventors: BRYAN, Edward L. Dallas, TX 75248 (US) CAMPBELL, Thomas M. San Antonio, TX 78250 (US) HUGG, Steven B. San Antonio, TX 78281 (US) HOFFMAN, Leslie B. San Antonio, TX 78229 (US) BREWER, Timothy Denver City, TX 79323 (US) (74) Representative: Punschke, Edgar  c/o EGLI PATENTANWÄLTE Horneggstrasse 4 CH-8008 Zürich CH-8008 Zürich (CH)