Page 207 - Reservoir Formation Damage

188 Reservoir Formation Damage

Plugged tube

Nonplugged tube

^ ^ S~A

Figure 10-3. Pore throat plugging 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).

= C 4K (10-14)
A f
in which the new constant is given by:
2
C — C I A (10-15)
<- — <- ' ™-
Pore filling occurs near the inlet face of the core when a suspension
of high concentration of particles in sizes larger than the size of the pore
throats is injected into the core as depicted in Figure 10-4. The per-
meability, K c, of the particle invaded region decreases by accumulation
of particles. But, in the uninvaded core region near the outlet, the
permeability of the matrix, K m, remains unchanged. The harmonic mean
permeability, K, of a core section (neglecting the cake at the inlet face)
can be expressed in terms of the permeability, K c, of the L c long pore
filling region and the permeability, K m, of the L m long uninvaded region as

(10-16)
which can be written as:

K(t) = L/[L cR c(t) (10-17)