Numerical simulation of retention and release of colloids in porous media at the pore scale

Abstract

Transport of a solid colloidal particle was simulated at the pore scale in presence of surface roughness and particle/pore physicochemical interaction by adopting a “one fluid” approach. A code developed in our laboratory was used to solve equations of motion, while implementing additional modules in order to take into account lubrication and physicochemical forces. Particles were recognized through a phase indicator function and the particle/fluid interface position at each instant was obtained by solving a transport equation. Roughnesses of different shapes were considered and the magnitude of the particle/pore physicochemical interaction was monitored through the change of the ionic strength of the suspending fluid. We first show that if pore surface is smooth no retention of the transported particle occurs whether the particle/pore surface is attractive or repulsive. However for shape roughnesses of “peak” or “valley”, particles may be retained inside pores or not depending on the considered ionic strength. In absence of particle retention, the residence time (the time needed for a particle to travel a characteristic pore distance) is finite and was found to be an increasing function of ionic strength for every considered roughness at fixed hydrodynamic conditions.International audienceTransport of a solid colloidal particle was simulated at the pore scale in presence of surface roughness and particle/pore physicochemical interaction by adopting a “one fluid” approach. A code developed in our laboratory was used to solve equations of motion, while implementing additional modules in order to take into account lubrication and physicochemical forces. Particles were recognized through a phase indicator function and the particle/fluid interface position at each instant was obtained by solving a transport equation. Roughnesses of different shapes were considered and the magnitude of the particle/pore physicochemical interaction was monitored through the change of the ionic strength of the suspending fluid. We first show that if pore surface is smooth no retention of the transported particle occurs whether the particle/pore surface is attractive or repulsive. However for shape roughnesses of “peak” or “valley”, particles may be retained inside pores or not depending on the considered ionic strength. In absence of particle retention, the residence time (the time needed for a particle to travel a characteristic pore distance) is finite and was found to be an increasing function of ionic strength for every considered roughness at fixed hydrodynamic conditions

Prediction of Productivity Decline in Oil and Gas Wells Due to Fines Migration: Laboratory and Mathematical Modelling

“…The near-rock-surface drift of detached fines is a combination of rolling, sliding, temporary detachment into fluid and return to the surface due to collision with asperities, etc. (Li et al, 2006, Yuan and Shapiro, 2011, Sefrioui et al 2013.…”

“…It is assumed that the particle rotates around a point of the contact circle at the moment of mobilisation; the rotation touching point is located on the contact area boundary. Following works by Derjiagin et al, 1975, Freitas and Sharma, 2001, Schechter, 1992, Torkzaban et al, 2007, Bradford et al, 2013, the lever arm is assumed to be equal to radius of the contact area of deformation by the normal force. It is calculated using the Hertz's theory:…”

“…Following works by Derjiagin et al, 1975, Freitas and Sharma, 2001, Schechter, 1992 let us determine the lever arm ratio from the deformation of the elastic particle on the cake surface by the total normal force. The total of gravity, electrostatic and lifting forces deforms a particle and creates a particle-martix contact area.…”

“…The Hertz's theory presents with the explicit formula for radius of the contact area which is equal to the normal lever l n . It was originally derived by Derjiagin et al, 1975 for the case of particle deformed by electrostatic force and was used for the colloidal particles attached to solid surface (Schechter, 1992, Torkzaban et al, 2007, Bradford et al, 2013: (B-1)…”

“…Navier-Stokes-based simulation of colloids behaviour at the pore scale, performed by Sefrioui et al 2013, exhibits the particle transport speeds significantly lower than the water velocity. Li et al, 2006 argue that those are the particles in the secondary energy minimum that perform the slow surface motion.…”