Williston Basin Petroleum

AP_750304890859.jpg

Political commentator Sean Hannity addresses the crowd while delivering his speech, "Get America Back to Work", Thursday, May 22, 2014, during the 22nd Williston Basin Petroleum Conference held in Bismarck, N.D. (AP Photo/Kevin Cederstrom)

8b57c08f26b20114550f6a706700fc04.jpg

This May 21, 2014 photo provided by the North Dakota Petroleum Council shows a group of eight-graders from West Fargo’s Cheney Middle School standing behind North Dakota Attorney General Wayne Stenehjem as he addresses the Williston Basin Petroleum Conference in Bismarck, N.D. The students were at the conference to present projects addressing problems caused by or related to oil development in the state. (AP Photo/North Dakota Petroleum Council, Renae Mitchell)

4188268226b20114550f6a7067003c66.jpg

This May 21, 2014 photo provided by the North Dakota Petroleum Council shows a group of eight-graders from West Fargo’s Cheney Middle School standing behind North Dakota Attorney General Wayne Stenehjem as he addresses the Williston Basin Petroleum Conference in Bismarck, N.D. The students were at the conference to present projects addressing problems caused by or related to oil development in the state. (AP Photo/North Dakota Petroleum Council, Renae Mitchell)

1d2b302c0345ec14540f6a7067003e54.jpg

Political commentator Sean Hannity addresses the crowd during his speech, "Get America Back to Work," Thursday, May 22, 2014, during the 22nd Williston Basin Petroleum Conference oil expo in Bismarck, N.D. (AP Photo/Kevin Cederstrom)

7fbc36a30345ec14540f6a7067008bd6.jpg

Political commentator Sean Hannity addresses the crowd while delivering his speech, "Get America Back to Work", Thursday, May 22, 2014, during the 22nd Williston Basin Petroleum Conference oil expo in Bismarck, N.D. (AP Photo/Kevin Cederstrom)

ced680f90345ec14540f6a706700aba4.jpg

Political commentator Sean Hannity addresses the crowd during his speech, "Get America Back to Work," Thursday, May 22, 2014, during the 22nd Williston Basin Petroleum Conference oil expo in Bismarck, N.D. (AP Photo/Kevin Cederstrom)

8264f3270307eb14540f6a7067008dd2.jpg

Political commentator Sean Hannity addresses the crowd while delivering his speech, "Get America Back to Work", Thursday, May 22, 2014, during the 22nd Williston Basin Petroleum Conference held in Bismarck, N.D. (AP Photo/Kevin Cederstrom)

5faee7160301ea14540f6a706700b48b.jpg

Billionaire oilman Harold Hamm, chairman of Oklahoma City-based Continental Resources Inc., delivers his speech, "Rock Steady in the Bakken", Thursday, May 22, 2014 during the 22nd Williston Basin Petroleum Conference held in Bismarck, N.D. (AP PhotoKevin Cederstrom)

4869e00e0312eb14540f6a706700cebd.jpg

Billionaire oilman Harold Hamm, chairman of Oklahoma City-based Continental Resources Inc., delivers his speech, "Rock Steady in the Bakken", Thursday, May 22, 2014, during the 22nd Williston Basin Petroleum Conference in Bismarck, N.D. (AP Photo/Kevin Cederstrom)