SAGD is used to recover heavy oil that is too deep to mine. A pair of horizontal wells is drilled from a central wellpad. In a plant nearby, steam generators powered by natural gas heat water and transform it into steam. The steam then travels through above-ground pipelines to the wells. It enters the ground via the steam injection (top) well. The steam heats the heavy oil to a temperature at which it can flow by gravity into the producing (bottom) well. The steam injection and oil production happen continuously and simultaneously. The resulting oil and condensed steam emulsion is then piped from the producing well to the plant, where it is separated and treated. The water is recycled for generating new steam.