In order to soften the oil sands before pumping begins, high- pressure steam is injected into the oils sand formation for several weeks. The heat softens the oil sands and the water vapour helps in breaking up the bitumen from the sand. The pressure that has been created causes cracks to be formed that assist in moving the bitumen to producing wells. After a section of oil sands have been saturated the steam is removed and the area is allowed to sit for several weeks, soaking up the moisture and steam. The bitumen will begin to flow more freely and then can be pumped up the well to the surface, and if the production rates begin to fall, cycle steam simulation is repeated.
Steam Assisted Gravity Drainage
This technology requires the horizontal drilling of two parallel wells which steam is pumped into the upper well creating a high temperature chamber that serves to heat and loosen thick bitumen. The heated bitumen is then pumped to the surface via the second horizontal well. This is one of the most popular and cost effective methods. This is a key technology that will be how most in-situ production is done in the years to come. Pairs of horizontal wells are drilled on above the other into the upper well. The steam heats the oil sands and it softens and drains into the lower well, where it naturally flows to the surface.
Whereas cyclic steam stimulation works best in formations like those near Cold Lake with good horizontal permeability, SAGD works better in deposits with good vertical permeability, like the Athabasca deposits near Fort McMurry.
Both cyclic steam stimulation (CSS) and (SAGD) use enormous amounts of natural gas to make the steam necessary to extract the bitumen. So in essence, developers are using energy to make energy.
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