Enhancing Oil Recovery with Hydrophilic Polymer-Coated Silica Nanoparticles

Abstract

Nanoparticles have been proposed for enhanced oil recovery (EOR). The research has demonstrated marvelous effort to understand the mechanisms of nanoparticles-EOR. Nevertheless, gaps still exist in terms of understanding the improved fluids and fluid-rock interactions by nanoparticles, which are the key driving forces for oil mobilization. This paper investigates four types of polymer-coated silica nanoparticles as additives for water flooding oil recovery in water-wet reservoirs. A series of flooding experiments were performed with nanoparticles at 0.1 wt.% in seawater at ambient conditions. The dynamics of fluids, fluid-rock interface interactions and fluid flow behavior were characterized in order to understand oil recovery mechanisms of nanoparticles. Experimental results showed an increase in oil recovery up to 14.8%-point with nanofluid injection compared to an average of 40% of the original oil in place (OOIP) obtained from control water flood test. Moreover, the nanoparticles mobilized residual oil and incremented oil recovery up to 9.2% of the OOIP. Displacement studies show that no single mechanism could account for the EOR effect with the application of nanoparticles. Instead, the mobilization of oil seemed to occur through a combination of reduced oil/water IFT, change in the rock surface roughness and wettability to more water-wet, and microscopic flow diversion due to clogging of the pores.

Experimental Investigation of Polymer-Coated Silica Nanoparticles for EOR under Harsh Reservoir Conditions of High Temperature and Salinity

“…In addition, the IFT reduction can be due to the surface-active polymer molecules surrounding the surface of the NPs that provide steric repulsive forces and stabilization of the NPs suspension. Comparing the results of the IFT data from previous studies at room temperature [ 15 , 17 ], for the same NPs, the greatest IFT reduction is achieved at elevated temperature. This indicates that the wetting properties and the binding energy of the NPs to the oil/water interface increase with temperature.…”

“…The authors associated the EOR effect to the NPs’ ability to decrease the injection pressure; the authors argued that displacement pressure decrease is related to the formation of a wedge film between the oil and the rock surface. More recently, Bila et al [ 15 , 16 ], Bila and Torsæter [ 17 ] carried out a series of flooding experiments with polymer-coated SiO NPs in Berea sandstone core plugs. Their studies revealed an incremental recovery ranging from 2.6% to 14% of the OOIP.…”