Williston Basin Petroleum

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FILE - In this May 22, 2012, file photo, workers erect an oil pump at the Williston Basin Petroleum Conference and Expo in Bismarck, N.D. The three-day Williston Basin Petroleum Conference and Expo starts Tuesday, May 20, 2014, at the Bismarck Civic Center, which is undergoing a $27 million expansion, in part because of the soaring interest in the oil conference. (AP Photo/James MacPherson)