Viscosity measurements of CO2-in-water foam with dodecyl polypropoxy sulfate surfactants for enhanced oil recovery application

Abstract

Apparent viscosities of CO2-in-water foams were measured in a wide range of shear rate from 50 to 10 5 inverse second for enhanced oil recovery (EOR) application. The CO2-in-water dispersions, made of 50: 50 weight proportions of CO2 and water with 1 wt.% surfactant concentration, were prepared in high-pressure recirculation apparatus under pressure where CO2 density becomes 0.7, 0.8, and 0.9 g/mL at each temperature of 35, 45, and 55 degrees C. The surfactants used for the foam generation were sodium dodecyl poly-propoxy sulfates with average propoxylation degrees of 4.7 and 6.2. The foam viscosity showed shear thinning behaviors with power-law indices ranging from 0.80 to 0.85, and approached a Newtonian regime in the lower shear rate range at several tens of inverse second. Zero-shear viscosity values projected from experimental data based on Ellis model were as high as 57.4 mPa.s and enough to control the mobility of water and CO2 in oil reservoirs.