Rheology of Viscous CO2 Foams Stabilized by Nanoparticles under High Pressure

Abstract

Foamed fluids with carbon dioxide in the gas phase have been recently studied as fracturing fluids to develop unconventional resources. This type of fracturing fluid is superior to water- or oil-based fracturing fluids for unconventional reservoirs, which are prone to damage by clay swelling and blocking of pore throats in water- or oil-rich environments. Conventional CO2 foams with surfactants have low durability under high temperature and high pressure, which limit their application. Nanoparticles provide a new technique to stabilize CO2 foams under harsh reservoir conditions. As CO2 foams will be applied as carrier fluids for proppant transport, it is essential to determine the in situ rheology of CO2 foams stabilized by nanoparticles under reservoir conditions in order to predict proppant transport and effective microchannels in reservoir fractures for improving oil production. This work studied the in situ shear viscosity and foam stability of supercritical CO2 foams stabilized by nanosilica (SiO2) i...