In a continuing effort to improve economics of oil recovery, the feasibility of using lignosulfonate with other surfactants for mobility control in CO2 flooding was evaluated. The laboratory tests were designed to quantify 1) the foam property of lignosulfonate with surfactant mixtures, and 2) the incremental oil recovery resulted from using such a mixture system.

The properties of foam were evaluated using a high-pressure foam durability apparatus in which the interfacial tension and stability of foam were determined. The mobility reduction of foam and the oil recovery efficiency were evaluated by conducting coreflooding experiments in a composite core, which contained well-defined high and low permeability regions in parallel to the flow direction.

Our results showed that lignosulfonate was compatible with most of the tested surfactants in generating high pressure CO2-foam. Lignosulfonate is a weak foam former by itself, however, it becomes a good foaming agent when mixed with other surfactant. Using such a mixture system in coreflooding experiments resulted in a significant improvement in oil recovery with a smaller amount of more expensive foaming agents and foam volume.

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