The design of chemical flooding systems has been and remains quite complex due to the many interactions that can occur between not only the various constituents in the chemical slug but also with the reservoir itself. This paper discusses many of the interactions that occur between surfactants, polymers and alkalis in a mixed system design. Specific focus is directed towards the benefits mixed alkalis impart to the overall design such as 1) water and reservoir conditioning, 2) adsorption/retention reduction, 3) emulsification improvement, 4) wettability alteration, and 5) improved sweep efficiency and mobility control.

Data are presented and discussed to show how such systems can be designed and what parameters to consider in maximizing chemical survivability, transport, and effectiveness. Effects such as consumption, ion exchange, precipitation, and propagation are discussed for a buffered mixed alkali that is tailored to a specific reservoir environment. This approach expands the horizon for alkaline chemicals and indicates one of the few remaining economically feasible directions for chemical recovery systems in todays oil market.

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