Marco A. Ruiz

Anomalous Heavy-Oil Rheological Thinning Behavior upon Addition of Nanoparticles: Departure from Einstein's Theory

Heavy and extra-heavy oils generally exhibit high viscosity, which is detrimental to their production, transport, and refining. The oil & gas industry has thoroughly investigated the use of chemical agents to improve the mobility of these types of low-quality crude oils at the surface as well as under reservoir conditions for many years. In this sense, the main objective of this paper is to provide unexpected experimental evidence of heavy oil and extra-heavy crude oils viscosity reduction resulting from the presence of nanoparticles (NPs) of different chemical natures (SiO2, Fe3O4, and Al2O3), particle size, surface acidity, and concentration at low-volume fractions. The viscosity of the enhanced fluids was measured using a rotational rheometer at shear rates varying between 1 and 75 s−1. Upon addition of NPs, viscosity reduction was observed in all cases evaluated. The maximum viscosity reduction of roughly 52% was obtained at a concentration of 1000 mg/L with 7 nm SiO2 NPs at low shear rate, below 10 s−1, contrary to expectations from Einstein’s viscosity theory in particulate systems. A mathematical model based on a modification to the Pal and Rhodes Model for the viscosity of suspensions is proposed in this work. The said model was validated successfully using experimental data, as evidenced by RSME% values lower than 10%. The importance of our findings lies in the lack of previous experimental and theoretical data in the open literature showing heavy crude oils viscosity reduction in the presence of NPs.

RETRACTED: Striking behavior of the rheology in heavy crude oils by adding nanoparticles:

At the request of the Publisher, the following article has been retracted for redundant publication. Taborda EA, Franco CA, Ruiz AM, Alvarado V, Cortés FB (2017) Striking behavior of the rheology in heavy crude oils by adding nanoparticles. Adsorption Science & Technology. Epub ahead of print 29 August 2017. DOI: 10.1177/0263617417727996. After publication, the Adsorption Science & Technology Editorial Office became aware that this article had been simultaneously submitted to Adsorption Science & Technology, and two other journals: Chemical Engineering Communications and Energy Fuels, which resulted in the redundant publication of the above article. The above article is near-identical to the following articles published by the same group of authors in Chemical Engineering Communications and Energy & Fuels. Taborda EA, Franco CA, Ruiz AM, Alvarado V, Cortés FB (2017) Anomalous Heavy-Oil Rheological Thinning Behavior upon Addition of Nanoparticles: Departure from Einstein’s Theory. Chemical Engineering Communications 204(6): 648–657. Taborda EA, Franco CA, Ruiz AM, Alvarado V, Cortés FB (2017) Experimental and Theoretical Study of Viscosity Reduction in Heavy Crude Oils by Addition of Nanoparticles. Energy Fuels 31(2): 1329–1338.