CO2-FOAMS STABILIZATION IN BRINE BY REDUCING DRAINAGE AND COARSENING USING AMINE OXIDE SURFACTANTS

A great challenge for oil industry is the development of foam to be used as a mobility controller in enhanced oil recovery (EOR) process in heterogeneous Brazilian Pre-Salt reservoirs. In special, producing CO2-foams in saline environments is a great challenge, since fast gas diffusion and reduction of electrical double layer promote fast coarsening and coalescence of bubbles. One possible strategy to arrest the destabilization mechanism and enhance the foam stability is to use zwitterionic amine oxide surfactants as a foaming agent because these molecules can form strong hydrogen bonds among themselves in acidic reservoir pH.1 However, a significant improvement in CO2-foam stability was only observed in the current study when using the longer chain surfactant. This behavior was attributed to the synergy between increased attractive hydrophobic interactions of alkyl chains and reduced repulsion among ionic surfactant heads mediated by hydrogen bonds, which led to the formation of large surfactant aggregates in bulk. The consequence is a significant increase in viscosity of the aqueous phase able to slow down the coarsening and drainage rate of CO2-foam. These results improve the insight about CO2-foam stability under harsh salinity conditions and important aspects to a foaming agent selection in EOR process.