Behavior and application of VES-18 clean fracturing fluid

VES-18 clean fracturing fluid is mixed with cationic quaternary ammonium and organic salt salicylate. The main behavior of VES-18 is investigated and tested on site. The results showed that VES-18 possessed a good temperature resistance and time stability. At room temperature and high shear rate of 170 s^-1, the viscosity of VES-18 is about 11 mPa·s. As the shear rate increased from 200 s^-1 to 1 000 s^-1, the viscosity declined slowly. And the viscosity-shear rate-decreasing curve is higher than rate-increasing curve. The curve of viscoelasticity showed that the elastic modulus was always bigger than the viscous modulus at the range of the stress scan. In the test of the simulated dynamic sedimentation, the time of VES-18 is greater than the time of the higher-viscosity guanidine and glycerol, which reflected the good carrying capacity of VES-18. Both a small amount of crude oil and gel breaker PJJ could make VES-18 broken completely within 4 hours. The breaking results are satisfactory. The viscosity of the gel-breaking liquids is reduced to less than 3 mPa·s, and the surface tension is low. The gel-breaking liquids had no residue content and had good compatibility with the formation.