(19)

(11)

EP 0 256 080 A1

(12)

(43) Date of publication: 24.02.1988 Bulletin 1988/08 (21) Application number: 87901090.0 (22) Date of filing: 04.02.1987

(51) International Patent Classification (IPC):  G01B 17/ 02( . ) G01S 7/ 64( . ) (86) International application number: PCT/GB1987/000081 (87) International publication number: WO 1987/004783 (13.08.1987 Gazette 1987/18)

(84) Designated Contracting States: AT BE CH DE FR GB IT LI LU NL SE (30) Priority: 06.02.1986 GB 19860003010 (71) Applicant: BRITOIL PLC Glasgow, G2 5LJ (GB)	(72) Inventors: HAYWARD, Gordon Glasgow (GB) McNAB, Alistair Renfrew PA4 0UH (GB)