Page 206 - Reservoir Formation Damage

Single-Phase Formation Damage by Fines Migration and Clay Swelling 187

Surface
deposits

Figure 10-2. Pore surface deposition in a core (after Civan, 1994; reprinted
by permission of the U.S. Department of Energy; after Civan 1992 SPE;
reprinted by permission of the Society of Petroleum Engineers).

somewhere along the tube, by a single particle to stop the flow through
that particular tube. Therefore, the cross-sectional areas of the individual
tubes, A h, do not change. But, the number of tubes, N np, open for the flow
is reduced as depicted in Figure 10-3. The area of the tubes eliminated
from service is given by:

(10-12)
A p=N pA h
The number of tubes plugged is estimated by the ratio of the total volume
of pore throat blocking particles to the volume of a single particle of the
critical size.

(10-13)

The critical particle size, d, is defined as the average size of the critical
f
pore constrictions in the core. d is the volume fraction of particles in
the flowing phase, having sizes comparable or greater than d. p p is the
particle grain density. p p/ is the mass concentration of particles in the
flowing suspension of particles. Because A h is a constant, Eq. 10-7 leads
to the following permeability to open flow area relationship: