(19)

(11)

EP 1 159 626 A2

(12)

(88) Date of publication A3: 28.12.2000 (43) Date of publication: 05.12.2001 Bulletin 2001/49 (21) Application number: 00905475.0 (22) Date of filing: 09.02.2000

(51) International Patent Classification (IPC)7: G01R 31/04 (86) International application number: PCT/NO0000/050 (87) International publication number: WO 0048/020 (17.08.2000 Gazette 2000/33)

(84) Designated Contracting States: AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE (30) Priority: 10.02.1999 NO 990626 (71) Applicants: Schlumberger Holdings Limited Road Town,Tortola (VG) DE GB IT NL  SERVICES PETROLIERS SCHLUMBERGER 75007 Paris (FR) FR	(72) Inventor: HATTELAND, Kjell N-3440 R yken (NO) (74) Representative: Stoole, Brian David  WesternGeco,Intellectual Property Law Department,Schlumberger House Gatwick Airport,West Sussex RH6 0NZ Gatwick Airport,West Sussex RH6 0NZ (GB)