Surfactant Flooding Evaluation for Enhanced Oil Recovery in Sandstones Reservoirs

Abstract

This research work considered surfactants for chemical oil recovery applications. Surfactant flooding is an EOR technique applied for decreasing capillary effects by molecular performance alterations on water-oil interface between injected water and displaced oil. In most situations, this method is implemented as a tertiary flood near of the end of waterflooding but it could be conducted after the initial stage of field production when oil saturations are high in the porous media. By an injector well, required volumes are introduced to the reservoir with the defined surfactant formulations for developing a new stabilized oil bank via ultralow interfacial tension between oil and water phases. The experimental methodology included Phase Behavior and Coreflooding tests for making comparative analyses between oil production responses of different configurations of surfactant flooding method. The phase behavior tests were conducted to select the best surfactant formulations through interfacial tensions and solubilization ratios determinations of different concentrations of five commercial surfactants: three anionic surfactants (Stepanol, sodium dodecyl sulfate and ammonium dodecyl sulfate) and two no-ionic surfactants (SPAN-20 and TWEN-20). Previously, it was performed surface tensions measurements to identify the critical micellar concentration (CMC), characteristic of each surfactant. The selected primary surfactant and co-surfactant formulations were tested for enhanced oil recovery using coreflood tests on high permeability sandstones from Bocatutu Formation. In these tests, the primary formulation solutions were followed by polymeric drive solutions injection. The tested formulations were also tested for porous media adsorption, evaluating surfactant losses during a surfactant flooding. The results are useful for running numerical simulation cases and single well field projects.