Viscosifying surfactants for chemical EOR

This work describes proprietary surfactant-based viscosifying fluids for Chemical EOR applications. The viscosity is induced by wormlike micelles formed by self-assembled surfactants. Prior to a deeper analysis of fluid flow profile, the viscosity of the fluid has been screened using a millifluidic set-up developed at Rhodia LOF. Viscosity measurements, at low surfactant concentrations (0.1% to 0.5 % w/w), have been recorded in a wide range of reservoir conditions (including formation brine with up to 200 g/L TDS). Data show that the system is salt tolerant with a positive impact of brine concentration on the viscosity. Thermal stability of viscosifying surfactants perfomed in anaerobic conditions show excellent stability even in hard brine. A miniaturized core flood test developed at Rhodia LOF has been used to measure fluid propagation as well as adsorption in single-phase conditions in representative porous material (Clashach sandstone). An excellent correlation has been found between bulk viscosity and rheology in porous media. Core-flood experiments have been performed on a specific reservoir case, showing the ability of viscosifying surfactant to displace residual oil. Simulations of viscosifying surfactants performance versus waterflood and polymer flood have been performed to extrapolate recovry factors in a 5 spot pattern.