Steam Assisted Gravity Drainage (SAGD) is a steam drive process in which at least one horizontal well near the bottom of the reservoir is used for oil production and one horizontal or several vertical injection wells are used for steam injection. In the current process, injection wells are located around 3-5 meters above the production well. As steam is being continuously injected into the reservoir, it forms an expanding chamber above the production well at a constant temperature based on the reservoir pressure. In this process, heated oil normally drains to the lower well by gravity and is produced from the reservoir.
In-Situ Combustion (ISC) is basically a burning front that slowly moves from an injection well to one or more production wells. The process is initiated by injecting air into the injection well surrounded by an array of production wells. After permeability development for gas, the burning front starts moving forward to the production wells. Normal air, enriched air or pure oxygen can be used to support combustion. Oil is displaced by vaporizing action of resulting front as well as the sweep provide by combustion product gases and hot water/steam. The process is fuelled by a small fraction of the oil generally the heavier components, which are burned as fuel by the advancing front.
