(128d) Foam Mobility Control: An Enhanced Oil Recovery Technique

In Enhanced Oil recovery techniques a significant fraction of the oil-in-place is left in the ground after primary or secondary recovery due to various reasons. Gas injection is one method used to extract these oils. There are basically four types of gases used in gas injection: natural hydrocarbon gas, inert gas, carbon dioxide, and steam; but in all cases there is the problem of gravity override.

Gravity override meaning the preferential movement of the injected gas through the upper part of the reservoir due to the lighter density of gas compared with oil. Gravity override causes early gas breakthrough in production wells and hence, reduced oil recovery. The steam is injected into the ground to reduce the viscosity of the oil and to make the oil more mobile. Unfortunately, due to gravity over ride, as steam rises to the top of the reservoir. Together with reservoir heterogeneity, gravity override results in early steam production and reduced volumetric sweep efficiency. Hence recovery is not improved to the degree desired. The injection of a permeability blocking agent would do the required. Various scientist have reviewed the selective blockage of fluids in thermal recovery projects and concluded that foam is best suited for this purpose. The foam is found to be promising to work in alkaline/surfactant processes to replace or supplement polymer as mobility control agent. The present study deals with the advancements in the foam mobility control for the recovery of unrecovered crude oil from the reserve.