A aerial image shows a train entering a depot along the Burlington Northern Santa Fe (BNSF) rail line outside of Williston, North Dakota in this March 12, 2013 file photo. Philadelphia Energy ... more 
A aerial image shows a train entering a depot along the Burlington Northern Santa Fe (BNSF) rail line outside of Williston, North Dakota in this March 12, 2013 file photo. Philadelphia Energy Solutions' 350,000 barrel-per-day Pennsylvania refinery is now processing a fifth of all oil produced in North Dakota's prolific Bakken shale oil formation and the plant could take more from there or other sources. REUTERS/Shannon Stapleton/Files (UNITED STATES - Tags: BUSINESS ENERGY ENVIRONMENT COMMODITIES TRANSPORT) less 
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Reuters | Photo By SHANNON STAPLETON / Reuters
Thu, Oct 3, 2013 12:02 PM EDT