On the influence of ionic strength on colloid transport in porous media in the presence of a rough surface : numerical simulation at the microscopic scale

Abstract

The understanding of Colloids transport, deposit or detachment in porous media is of central importance in many practical problems such as filtration, environmental issues and petroleum engineering. In particular, the interaction of colloids with the grain surfaces is a complex problem involving combination of short range physico-chemical forces, acting at the “interface scale” with the hydrodynamics in the pore space. The understating of the processes at these small scales is crucial for the description of colloid transport processes under different physicochemical and hydrodynamic conditions at larger scales. General experimental features of colloid deposition and their detachment after a flooding with brine of ionic strength and pH different from the resident one have been reported in literature and successfully predicted using DLVO theory (Canseco et al., 2009). However and despite various efforts, such prediction remains only qualitative. It is usually believed that the observed discrepancies arise from grain or colloid heterogeneities. Such heterogeneities may concern electrostatic charge or surface topography or both.(Ducker et al., 1991; Elimelech & O’Melia, 1990). The objective of this work is to study the influence of grain surface roughness on the transport, deposit and detachment of a colloidal particle under various physicochemical and hydrodynamic conditions. For this purpose, direct numerical simulations of the transport of a single particle near the fluid/solid interface have been performed.