(354g) 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: nassar@ucalgary.ca

Abstract

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 self–associating 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.