Propagation of surfactant and polymer flow in natural carbonate cores

Abstract

This paper presents an experimental and analytical study of comprehensive effects of surfactant and polymer in aqueous solutions on the propagation in carbonates. Single-phase flow tests of surfactant, polymer and surfactant-polymer mixture were respectively conducted on natural carbonate core plugs at high temperature and high salinity reservoir conditions. The effect of different factors on chemical propagation was taken into account by use of a convection-dispersion model. The dynamic adsorptions of two amphoteric surfactants at 2000 mg/L concentration onto the carbonate rocks were 0.21 and 0.17 mg/g-rock, respectively. The dynamic adsorptions of a sulfonated polymer at 2000 and 5000 mg/L were 0.11 and 0.17 mg/g-rock, respectively. Surfactant-polymer mixtures in aqueous solutions were co-injected to evaluate their competitive adsorption, showing the surfactant adsorption was reduced by approximately 50%. The dispersion coefficient of the chemicals in the carbonate cores was in the magnitude of 10 −3 cm 2 /s. Caused by dispersion and adsorption, chemical concentration reduction occurred obviously during the propagation in carbonate porous media. Chromatographic separation took place in the surfactant-polymer co-injection scheme, which was estimated by modeling as well. • Study the phenomenon of chemical propagation in water-swept area before chemicals reach the trapped crude oils. • Quantify the factors in chemical injection for permeable carbonates at high temperature and high salinity conditions. • Investigate the way to have more efficient chemical injection.