Nanotechnology is well established in several industries. However, the emergence of its application is recent in the oil and gas industry; a fact corroborated by the current surge of publication in literature. Interestingly, advancement in research has shown that nanotechnology can improve the rheological properties of surfactant-based fluids (SBF) and polymeric fluids.
To date, this application focuses more on polymeric fluids than on SBF. Furthermore, a few or none of the studies address the detrimental effect of nanotechnology on rheological properties of these fluids once certain limits are exceeded. Likewise, little or no information is available regarding the application of nanotechnology in SBF-polymeric fluid blends.
This paper presents an experimental investigation of nanotechnology on the rheological properties of SBF, polymeric fluids, and SBF-polymeric fluid blends. The surfactant-based and polymeric fluids are composed of 5% SBF in 4% KCl and 33 lb/Mgal guar in 4% KCl respectively. Blend A was prepared by adding 75% vol. of surfactant-based fluid to 25% vol. of polymeric fluid; while Blend B resulted from the addition of 25 and 75% vol. of these fluids. The 20 nm silica nanoparticles were added to achieve three nano-fluid concentrations (0.058%, 0.24%, and 0.4% wt.) for each clean fluid. Rheological data were gathered by conducting viscometry and frequency sweep tests using the Bohlin CS-50 rheometer within a temperature range of 75 to 175 °F. The results indicate that 20 nm silica nanoparticles are beneficial in terms of enhancing rheological properties in surfactant-based and polymeric nano-fluids up to particle concentration of 0.24% and 0.4% respectively. Blend A nano-fluids show similar results at 0.058%, and only at 0.4% at high shear rates. Similarly, Blend B displayed favorable results up to 0.24% and at high temperature applications only (125 to 175 °F). Finally, relative viscosity correlations are developed for predicting viscosity of nano-suspensions.
The application of nanotechnology on the rheological properties of SBF, polymeric fluids, and SBF-polymeric fluid blends delivers on great benefits, if nanoparticle concentrations are carefully selected. These nano-fluids will be applicable for oilfield operations such as hydraulic fracturing.