Anionic Wormlike Micellar Fluids that Display Cloud Points:  Rheology and Phase Behavior

Abstract

We report our investigations into the self-assembly of sodium oleate (NaOA) in the presence of a binding salt (triethylammonium chloride, Et 3 NHCl) simple salt (potassium chloride, KCl). Both salts promote the growth of long, wormlike micelles in NaOA solutions, thereby increasing the fluid viscosity. The significant difference with the Et 3 NHCl salt is that it also modifies the phase behavior of NaOA solutions. Specifically, NaOA/Et 3 NHCl solutions display cloud points upon heating, followed by phase separation into two liquid phases. Such cloud point behavior is rarely observed in ionic surfactant systems, although it is common in nonionic surfactant solutions. Interestingly, while cloud points are not observed with KCl, the addition of KCl to NaOA/Et 3 NHCl solutions further lowers the cloud point temperature. Also, in the case of tetraethylammonium halide salt, neither a cloud point nor an increase in viscosity is observed. The clouding in the case of Et 3 NHCl is attributed to the temperature-induced aggregation of anionic micelles whose surface is covered by bound counterions.

Nanoparticles induced micellar growth in sodium oleate wormlike micelles solutions

“…Cryo-transmission electronic microscopy (cryo-TEM) [12] and extensional rheology measurements [13] were employed to characterize the mixed NaOA/OTAB wormlike micelles. Kalur [14] showed that the addition of triethylammonium chloride (Et 3 NHCl) to NaOA solutions could induce the formation of wormlike micelles with certain counterions. The addition of inorganic salts, such as KCl, NaCl, Na 2 CO 3 , and NaCl/NaOH could give rise to a highly viscoelastic fluids of NaOA solution [14,15].…”

CO2-responsive anionic wormlike micelles based on natural erucic acid

“…Moreover, the gel-like fluid after carbon dioxide streaming can also recover to its initial state by simply exposing to air for about 4 d. Although these two systems show some advantages over multicomponent ones, the surfactants used here are only obtained by complicated and time-consuming organic synthesis, and the cationic surfactants are demonstrated to be less biodegradable and more toxic than their anionic counterparts. [41][42][43][44] Thus, simpler and less toxic carbon dioxide-responsive wormlike micelles are highly desirable.…”

Self-assembly networks of wormlike micelles and hydrophobically modified polyacrylamide with high performance in fracturing fluid application

“…6 Effect of temperature on the dynamic viscoelastic spectra (a) and steady shear plots (b) of the WLMs system Fig. 7 Effect of temperature on the dynamic viscoelastic spectra (a) and steady shear plots (b) of the WLMs/HMPAM system we suppose that the zero-shear viscosity η 0 relates to the temperature by the Arrhenius equation [26] and its logarithmic form can be presented as:…”

“…Both the systems were heated with an average speed of 3°C/min to the target temperature in order to simulate the heating process of fracturing fluids from the wellhead to the down hole, and then continuously sheared for 90 min under the target temperature, and the entire process was kept at a constant shear rate of 170/s. After a 90-min continuous shear under the target temperature, the curves of viscosity values versus time of the two systems were maintained at 50-60 mPa s, which is the minimum viscosity value required for fracturing fluids to suspend the proppants [26], indicating that the highest applicable temperature of WLMs and WLMs/ HMPAM systems can reach to 80 and 110°C, respectively. Compared with the pure WLMs fracturing fluids, the self-assembly ones exhibited higher applicable temperature without increasing the concentration of the surfactant.…”