Dual surfactant systems for enhanced oil recovery at high salinities

Miller, D.J., Von Halasz, S.-P., Schmidt, M., Hoist, A. and Pusch, G., 1991. Dual surfactant systems for enhanced oil recovery at high salinities. J. Pet. Sci. Eng., 6: 63-72. Surfactants for the enhanced recovery of crude oil were studied with a model oil by means of phase experiments and core floods. As single surfactants, alkylphenol ether sulfonates have only a limited potential for enhanced oil recovery at high salinities. If the surfactant is made hydrophilic enough to dissolve in brine it is no longer able to form a microemulsion with the hydrocarbon. This problem may be solved by using dual surfactant systems consisting of alkane sulfonate and ether sulfonate. At high salinities these surfactant combinations dissolve in brine to form a homogeneous dispersion. Such mixtures are also cheaper than the ether sulfonate alone. Core floods with a model oil demonstrate the efficiency of these surfactant mixtures and their compatibility with a modified polyacrylamide polymer specially developed for high salinity reservoirs.