The steam injected into the oil sands reservoir in the SAGD process helps bitumen flow in two ways – reducing its viscosity by heating it, and increasing the pressure in the reservoir to help it flow.
As the steam condenses back to a liquid state when it cools, the pressure declines. Co-injecting trace amounts of a non-condensable gas, like methane, with the steam helps keep consistent pressure in the reservoir. The use of non-condensable gas frees up steam capacity to be redeployed into predrilled wells, providing a very efficient way of adding low cost barrels.
In addition to gas injection, the eMSAGP program includes drilling ‘infill wells’ – single collector wells that are placed between producing SAGD well pairs. Working together with non-condensable gas injection, infill wells take advantage of heat that is already in the reservoir, without requiring additional steam.
*Steam and Gas Push (SAGP) was invented by the late Dr. Roger Butler, who also invented the SAGD process.