Self-regulating solutions for proppant transport

Fluids displaying flow induced viscoelasticity are tested for proppant placement and flow back. The viscosity is self-regulating and obviates the need for viscosiflers and breakers. The flow induced viscoelasticity degrades at higher flow rates enabling good injectivity. Particle tracking velocimetry is performed to study the influence of flow rate on the particle settling under different flow regimes. These tests show that above a critical flow rate particles are maintained in suspension and settle with a constant velocity giving the fluid an apparent viscosity up to 200 mPa s compared to a zero-shear viscosity of 2 mPa s. During flowback in porous proppant packs the fluid has a low flow resistance with a viscosity comparable to its zero-sheared state. Pack permeability is retained after flowback of the fluid thereby resulting in optimum fracture clean-up. (C) 2016 Elsevier Ltd. All rights reserved.