Effects of type of salt on nanoparticles-stabilized carbon dioxide foam in enhanced oil recovery

Abstract

Foam is employed to improve the efficiency by which the displacing fluid sweeps the reservoir and contacts and recovers oil. However, it is known that foam are both thermodynamically and kinetically unstable systems that readily destruct as a result of film drainage, drying, film breakup and gas diffusion. Study had found that solid nanoparticle may promote foam stabilization. The foams stability depends on the particle size, shape, concentration and hydrophobicity, as well as on the type of surfactant used. The objectives of this study are to determine the effectiveness of different type of salt on CO2 foam stability by using various concentrations of nanoparticle at fixed surfactant concentration (AOS) and dispersion salinity, and to determine oil recovery performance of each type of salt and compare the results. Three types of salt (Sodium Chloride, Calcium Chloride and Magnesium Chloride) were used to create six different compositions of brine with total salinity of 3 wt%. A silicon dioxide nanoparticle was used in this study at four different concentrations; 0 wt%, 0.1 wt%, 0.5 wt% and 1.0 wt%. Alpha olefin surfactant (AOS) was used as the foaming agent at fixed concentration of 0.5 wt%. Red dye paraffin oil is used to represent the oil in formation. In the foam stability test, it was found that different type of salt requires different concentration of SiO2 to give optimum stabilization on foam. From this study, it was found that different type of salt would affect the stability of nanoparticle-stabilized foam. The 3 wt% CaCl2 at 0.5 wt% SiO2 gave most stable foam and highest oil recovery because of the greater stability of micelles to cause enhanced foam stability. Thus, one can conclude that the foam stabilities can only be enhanced by packing micelles of high stability in the foam lamellae.