The most common method of in situ oil sands production is called steam assisted gravity drainage (SAGD). In this technique, two parallel wells are drilled horizontally into the reservoir from a central well pad. Steam generated from a surface plant is pumped into the reservoir through the top well, causing the bitumen to soften and flow to the bottom of the chamber. The bitumen is then pumped to the surface from the producing (bottom) well.
Bitumen gets pumped to the surface along with water as an oil and condensed steam emulsion. This stream is separated and treated, before the water is recycled for generation of new steam. Operators recycle as much of the water for steam production as possible, but treatment of water to produce high quality boiler feed water (for steam production) can be challenging.
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