Synergistic effect of salts on inducing obvious viscoelastic behavior of cationic trimeric surfactant solutions

A viscoelastic system formed by the solutions of di(2-hydroxyl-dimethylene ether)-α,ω,γ-triple (dimethyloctadecylammonium chlorine) (18-4(OH)-18-4(OH)-18) is proposed to solve the problems of poor temperature and shear resistances of clean fracturing fluid. The apparent viscosity of 18-4(OH)-18-4(OH)-18 solution affected by inorganic salt, hydrotropic salt and their mixtures is investigated using steady state measurements. Meanwhile, the temperature and shear resistances of systems of 18-4(OH)-18-4(OH)-18 and several common single-chain surfactants are compared. The rheological experiments show that, the coexistence of NaSal and NaCl makes it easier for the system to promote micellar growth yielding wormlike micelles than single NaSal or NaCl. The apparent viscosity of 18-4(OH)-18-4(OH)-18 solution maintains over 87.5.mPa·s above 100.℃. The results indicate that there exists a synergistic effect in solutions of 18-4(OH)-18-4(OH)-18 trimeric surfactant with NaSal and NaCl.