Research on microstructure and rheological properties of recyclable NaOA/Na3PO4 viscoelastic micelle fracturing fluid

The electrolyte Na3PO4 solution is used to induce anionic surfactant NaOA to form wormlike micelle system. By using freeze-fracture transmission electron microscopy (FF-TEM) technology and rheology method, the research about Na3PO4 which induces NaOA to form micelle system under different mass fractions， was conducted on the functions like microstructure, rheological properties, gel breaking behavior and recycling. By measuring and analysis of physical quantities about dynamic modulus, shear viscosity, compound viscosity, etc. of the system, it was found that this micelle system shows wormlike net structure and good viscoelastic performance in a broad frequency. Using gel breakers, the gel breaking behavior of the system was studied, and combined with the test on rheological properties, it is proved that this micelle system is good for repeated use. Through comparison with the now maturely used hydroxypropyl guanidine gum (HPG) fracturing fluid and microcosmic FF-TEM of its breaking fluid, it shows that the NaOA/Na3PO4 viscoelastic micelle system has clear net structure and can achieve the breaking effectiveness equal to HPG after breaking by strong oxidant under moderate conditions. The above results show that the NaOA/Na3PO4 viscoelastic micelle system can be used as recyclable clean fracturing fluid system and has a broad application prospect.