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(11)

EP 2 347 083 A2

(12)

(88) Date of publication A3: 12.08.2010 (43) Date of publication: 27.07.2011 Bulletin 2011/30 (21) Application number: 09793358.4 (22) Date of filing: 08.10.2009

(51) International Patent Classification (IPC):  E21B 7/14(2006.01) E21B 43/114(2006.01) E21B 7/18(2006.01) (86) International application number: PCT/US2009/060003 (87) International publication number: WO 2010/042720 (15.04.2010 Gazette 2010/15)

(84) Designated Contracting States: AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO SE SI SK SM TR Designated Extension States: AL BA RS (30) Priority: 23.12.2008 US 140477 P 23.12.2008 US 140512 P 08.10.2008 US 103859 P 23.12.2008 US 140489 P (71) Applicant: Potter Drilling, Inc. Redwood City, CA 94063 (US)	(72) Inventors: WIDEMAN, Thomas, W. Milton MA 02186 (US) POTTER, Jared, M. San Carlos CA 94070 (US) POTTER, Robert, M. Rio Rancho NM 87124 (US) DREESEN, Donald Los Alamos NM 87544 (US) (74) Representative: Copsey, Timothy Graham et al Kilburn & Strode LLP 20 Red Lion Street London WC1R 4PJ London WC1R 4PJ (GB)