Experimental and theoretical investigation of CTAB microemulsion viscosity in the chemical enhanced oil recovery process

Of the most important methods of enhancing oil extraction from petroleum reservoirs includes injecting chemical materials of which surfactants have been found to play a significant role. In surfactant concentrations higher than critical micelle concentration (CMC), formation of micelles is started which will lead to change in the properties of microemulsion. In previous studies, the effect of transformation of micelle from spherical to cylindrical shape on the viscosity of DeAC (dodecyl ammonium chloride) microemulsion has been discussed. In this paper, application of CTAB (Cetyl trimethylammonium bromide, a cationic surfactant) in above CMC ranges has been studied based on the data from laboratory tests and proposed models in order to predict microemulsion viscosity. Moreover, the size of cylindrical micelles has been calculated using some mathematical equations for the first time. The results showed that the shape transformation from spherical to cylindrical happens to CTAB surfactant leading to vigorous increase in viscosity. Additionally, size calculation of micelles in different conditions and their comparison to pore throats dimension of porous media suggest that for certain conditions, they are adequately smaller than the pore throats. It is therefore suggested that CTAB surfactant may be utilized as a sole reagent in lowering IFT and mobility ratio instead of implementation of CTAB-polymer, making the possible chemical enhanced oil recovery (EOR) process less costly.