Flow-induced proppant carrying capacity

• Novel viscoelastic surfactants can reduce viscosifiers and breakers in fracturing.
• Viscoelastic surfactants form shear induced structures in discrete flow regimes.
• Particle settling in sheared viscoelastic fluids is tested in a fracture flow cell.
• Proppant carrying capacity is enhanced by induced elasticity at high flowrates.
• Fluids can be tuned to match rheological requirements of fracturing treatment.

A subclass of viscoelastic surfactant fluids are investigated as flow-dependent proppant carrying fluids. Shear-induced structure networks have the potential to eliminate the need for cross linkers and viscosity breakers associated with traditional fluids because they shear-thicken and shear-thin depending on the fluid pump rates in the fracture. Particle tracking velocimetry is used to visualize proppant settling velocity inside a fracture flow cell. We show that settling velocities in high shear flows are reduced by a factor 20 compared to settling in low shear ones and fluids at rest. Couette cell and oscillatory rheometry are used to investigate the induced viscoelasticity. The critical shear rate required for fluid thickening and the succeeding viscosity contrast ratio determine the extra proppant carrying capacity.