(19)

(11)

EP 1 730 384 A2

(12)

(88) Date of publication A3: 04.05.2006 (43) Date of publication: 13.12.2006 Bulletin 2006/50 (21) Application number: 05731196.1 (22) Date of filing: 24.03.2005

(51) International Patent Classification (IPC):  E21B 43/00(2006.01) (86) International application number: PCT/US2005/009988 (87) International publication number: WO 2005/098199 (20.10.2005 Gazette 2005/42)

(84) Designated Contracting States: DK GB NL (30) Priority: 29.03.2004 US 812337 (71) Applicant: Nalco Energy Services, L.P. Sugar Land, TX 77478 (US)	(72) Inventor: BLAIR, Cecil, Curtis East Bernard, TX 77435 (US) (74) Representative: Hock, Joachim  Müller-Boré & Partner Grafinger Strasse 2 81671 München 81671 München (DE)