A mixed ethanolamine-potassium-sodium carboxylate surfactant system was formulated by reacting 10 grams of tallow acid (product T11 from Procter and Gamble) with 1.3 grams of ethanolamine in water in the presence of 40 grams of sodium stearate (Norac Inc.), 30 grams of potassium carbonate and 10 grams of sodium carbonate. Sufficient water was added to generate one litre of a viscoelastic suspension. FIG. 13 shows the shear viscosity of the suspension for shear rates in the range from 0.1 s−1 to 100 s−1 at temperatures from 25 to 120° C. The viscosity increased with increasing temperature up to 80° C., and subsequent increases in the temperature resulted in a decrease in viscosity. The surfactant formed a clear, viscoelastic gel on heating. At a temperature of 120° C., the surfactant solution was able to generate a viscosity of 70 cP at a shear rate of 100 s−1.
