Polyhydroxy cationic viscoelastic surfactant for clean fracturing fluids: Study on the salt tolerance and the effect of salt on the high temperature stability of wormlike micelles

• A polyhydroxy cationic viscoelastic surfactant with excellent salt and temperature tolerance was synthesized. • The salt tolerance mechanism was analyzed from the molecular structure and intermolecular interaction. • The degree of temperature-response depends on the type of salt and its concentration. • The effects of salt and its concentration on temperature tolerance were analyzed from the molecular thermal motion. In this study, we designed and synthesized a polyhydroxy cationic viscoelastic surfactant (SY-TO). Though the FT-IR, 1H NMR and surface tension methods characterize and determine the structures and critical micelle concentration. Through the test of apparent viscosity, viscoelastic, and microstructure observation, we study the salt tolerance of SY-TO. And for the salt tolerance mechanism, we explain it from the molecular structure and hydrophilic headgroup. Additionally, through the high temperature rheological tests, we studied the effects of salt and its concentration on the behavior of wormlike micelles (WLMs) at high temperatures. In particular, the effects of salt and its concentration on temperature-response are analyzed. More importantly, the effects of salt and its concentration on the high temperature stability of WLMs were analyzed from the perspective of molecular thermal motion. Through the research on the salt tolerance mechanism of hydrophilic headgroup and the analysis of the effect of salt on the high temperature stability of WLMs, we hope it will be conducive to promote the preparation and wide application of salt and temperature resistant clean fracturing fluids.