Self-regulating solutions for proppant transport

• VES fluids are tested for a flow-regulated viscosifier- and breaker-free system.
• The fluid is Newtonian at low flowrates and viscoelastic at high flowrates.
• Proppant is suspended in the viscoelastic regime above a critical flowrate.
• Viscoelastic behavior disappears upon the secession of high shear rates.
• The fluid is low viscosity and Newtonian during flow through a proppant pack.

Fluids displaying flow induced viscoelasticity are tested for proppant placement and flow back. The viscosity is self-regulating and obviates the need for viscosifiers 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.