Page 267 - Reservoir Formation Damage

Two-Phase Formation Damage by Fines Migration 247

The dispersion term is considered for dissolved species, such as those
contained in the aqueous phase, but it is usually neglected for the particles.
In accordance with the experimental observations by Muecke (1979),
Liu and Civan (1993, 1995, 1996) have assumed that wettable particles
remain in the wetting phase and nonwettable particles remain in the
nonwetting phase and the intermediately wet particles are situated along
the interface. They did not consider the possibility of wettability alteration
of the particles and the pore surface in porous media and they assumed
that the dispersion terms are negligible for the particles. They considered
that the porous media has uniform wetting properties. Under these
circumstances, Eq. 11-31 simplifies significantly because q ju = 0 and the
particle loss only occurs from the fluid phases to the solid matrix (i.e.,
= f
qj = qjj ijjs'' J = W,N).
Liu and Civan (1996) considered a water/oil system flowing through a
homogeneous (i.e., one type—either water-wet or oil-wet—porous media).
They assumed that the wettability of the porous medium does not change
during the short period of time involving the typical laboratory core tests.

Wettability Transformation and
Interface Transfer of Particles

The literature on studies of the mechanisms of wettability alteration
and interface particle transfer is rather limited and insufficient to formulate
these processes accurately and rigorously. Therefore, Liu and Civan
(1996) have resorted to a simplified approach, which yielded reasonably
good results. They have combined the rate processes of the wettability
transformation and the phase to phase particle transfer into one step
assuming that the particles would immediately migrate into the phases,
which wet them once their wettabilities change from one type to another.
Based on the experimental observations and the studies of the mechanisms
of interface particle transfer of Ku and Henry (1987), Liu and Civan
(1996) assumed that the rate of the combined processes of wettability
transformation and interface transfer of particles can be expressed as being
proportional to the particle concentration according to:

QjlJL - (11-32)

Particle Retention in Porous Media

Although particle retentions may occur at various locations in porous
media by various mechanisms, only the most likely mechanisms are
considered here. The wetting and nonwetting particles preferentially