472728 Nanoscale Dynamics of Silica-Based Nanofluids for Asphaltene Removal and Wettability Alteration
Nanoscale dynamics of silica-based nanofluids for asphaltene removal and wettability alteration
Tatiana Montoya, Nashaat N. Nassar*, Gerardo Vitale
1Department of Chemical and Petroleum Engineering, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada.
Corresponding author e-mail: email@example.com
Asphaltenes form the solubility class that is considered the heaviest, most aromatic and most surface-active fraction of crude oil. Because of their complex chemical structures, polarizability and amphiphilic behavior, asphaltenes exhibit a selfassociating feature that promotes aggregation and subsequently increases the viscosity of crude oil. Due to these characteristics, asphaltenes can cause different problems at different stages of crude oil production, any of which cause a loss of productivity. Thus, understanding the adsorption and deposition of asphaltenes onto solid surfaces has practical significance for monitoring the fluid-property variations that are common during oil production. Therefore, the deposition mechanism of asphaltene onto sand and alumina surfaces and the factors influencing it are investigated in this study. This is because asphaltene deposition is important in many different domains of the oil industry, such as alteration of reservoir rock wettability because its potential to be adsorbed on reservoir rock, plugging of flow lines because of asphaltene deposit build-up, and refinery catalyst deactivation because of asphaltene adsorption at active sites, causing significant production losses. Accordingly, appropriate mitigation techniques, for surface exposed to asphaltene or operating conditions, can be identified.
It has been demonstrated that the use of nanoparticles may improve the mobility of oil and alter the formation wettability. This is because nanoparticles may be used as adsorbents and catalysts in the oil industry for enhancing in situ upgrading and recovery processes. Therefore, this study aims at inhibiting of formation damage caused by asphaltene deposition and subsequently enhance oil recovery using silica-based nanofluid flooding approach, with varying nanoparticle chemical surface.
The potential flow of silica-based nanofluids at concentration of 100 ppm with varying acidity in displacing the asphaltene layers adsorbed on silica surfaces is investigated in an attempt to explore the applicability of these nanoparticles as a chemical modifier to alter the reservoir wettability. The quartz crystal microbalance with dissipation (QCM-D) was used to determine the adsorption of the nanoparticles on silica or alumina which has a thin layer of asphaltenes (preadsorbed), and/or its removal. The operating variables studied were nanoparticles surface acidity, nanoparticle size, flowrate and temperature. The role of silica-base nanofluid on the wettability alteration and morphology mitigation of the asphaltene-contaminated (coated) silica surface was determined by contact angle measurement and atomic force microscope (AFM) imaging. Dynamic light scattering (DLS) was also used to determine the role of the modified chemical surface on aggregation. Thus, effluent samples were taken at different flowing times for DLS measurements. The measurements were conducted before and after the nanofluids flow. The results demonstrated the possibility of using basic nanoparticles to modify the wettability, through removing the hydrocarbon that adsorbed/deposited on inorganic solids (clays), in order to improve heavy oil recovery.
Keywords: Nanofluids, quarz crystal microbalance (QCM-D), Asphaltenes.