(19)

(11)

EP 2 379 813 A2

(12)

(88) Date of publication A3: 23.09.2010 (43) Date of publication: 26.10.2011 Bulletin 2011/43 (21) Application number: 09835651.2 (22) Date of filing: 17.12.2009

(51) International Patent Classification (IPC):  E02D 27/38(2006.01) E04H 7/20(2006.01) (86) International application number: PCT/US2009/068561 (87) International publication number: WO 2010/075186 (01.07.2010 Gazette 2010/26)

(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 (30) Priority: 23.12.2008 US 342503 (71) Applicant: Chevron U.S.A. Incorporated San Ramon, California 94583 (US)	(72) Inventors: SHOCKLEY, Lestle R. San Ramon California 94583 (US) BOROV, Vincent G. Martinez California 94553 (US) (74) Representative: Nash, David Allan  Haseltine Lake LLP Redcliff Quay 120 Redcliff Street Bristol BS1 6HU Bristol BS1 6HU (GB)