Southwestern Energy Company is an energy company engaged in natural gas and oil exploration, development and production. The Company operates through two segments: Exploration and Production (E&P) and Midstream Services. Its operations in northeast Pennsylvania are primarily focused on the unconventional natural gas reservoir known as the Marcellus Shale. Through its affiliated midstream subsidiaries, it is engaged in natural gas gathering activities in Arkansas and Louisiana. Its operations are principally focused on the development of unconventional natural gas reservoirs located in Pennsylvania, West Virginia and Arkansas. As of December 31, 2016, its estimated proved natural gas and oil reserves were 5,253 billions of cubic feet equivalent (Bcfe).