Development and Laboratory Study of Surfactant Fracturing Fluid for Oil and Gas Development
Surfactant dosage severely limits the application of viscoelastic surfactant(VES)fracturing fluids.In this study,a novel long hydrophobic double-bonded twin surfactant(ALA)was synthesized,and a low concentration ALA fracturing fluid was developed.When compounded with KCl solution,it showed the best salt tolerance and apparent viscosity in the KCl mass fraction range of 0.2%to 2.6%.The results of molecular simulation showed that the radius of gyration started to decrease when the mineralization of the simulated system was higher than mass fraction 2.2%KCl,and the high salt ions would destroy the hydration layer and decrease the radius of gyration.The viscosity of the VES fluid decreased from 405 mPa·s to 68 mPa·s as the temperature increased from 18℃to 107℃,and in addition,the solution exhibited good viscoelasticity and a tight network structure as confirmed by oscillatory measurements.Rheological tests of the fracturing fluid were conducted under the conditions of 170 s-1 and 107℃,and the results showed that 2.2%KCl+3%ALA surfactant solution had significantly superior rheological properties,and the viscosity could be maintained above 58 mPa·s after 120 min.Finally,the optimized fracturing fluid system was subjected to sand suspension test,glue breaking performance test and core matrix injury test,and the results met the industry requirements.
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