FILE PHOTO: Scott Sheffield, Chairman and Chief Executive Officer of Pioneer Natural Resources Company, speaks to guests and investors during the OGIS conference for oil and gas companies in New York, April 8, 2014. REUTERS/Eduardo Munoz /File Photo
FILE PHOTO: Scott Sheffield, Chairman and Chief Executive Officer of Pioneer Natural Resources Company, speaks to guests and investors during the OGIS conference for oil and gas companies in New York, April 8, 2014. REUTERS/Eduardo Munoz /File Photo