The influence of surfactant concentration on rheology and proppant-carrying capacity of VES fluids

Polymer-free VES fluids are used to minimize damage to the proppant pack to efficiently transport proppants into fractures. Proper investigation of the rheological properties and the proppant settling of the fluids play an important role in fracturing enginering.In this paper,the rheology and viscosity-temperature properties of the VES fracturing fluid were researched at the range of 1wt% to 6wt% of VES concentration using the HAAKE RS300 Stress-Controlled Rheometer. Proppant settling experiments are performed in static VES fluid. The results show that VES system behaves as a non-Newtonian shear-thinning fluid and the power law model can be used to describe fluid rheology within a certain range of shear rate and temperature. However, with the increase of shear rate and temperature, the fluid trends to Newtonian fluid. Apparant viscocity of the fluid first increases slightly with the temperature rising from 28°C, then, It would drastically reduce after reaching a peak. The temperature correspongding to the peak value increases with the concentration of VES,as well as the shear rates. When VES concentration is 4wt%, the fluid may generates stable micro-mesh wormlike micelle structure, which results in good viscoelasticity and high proppant-carrying capacity.