Page 232 - Reservoir Formation Damage

212 Reservoir Formation Damage

a* =
(10-157)

where a is the expansion coefficient of a unit clay volume, estimated by
(see Chapter 2):

a = a s - (a s -1) exp (-2Jk 4flV*) (10-158)

in which a is the expansion coefficient at saturation. The initial con-
ditions are given by:

(10-159)

Therefore,

(10-160)

and

(10-161)

Note k' r =0 for c>c' cr, k"= 0 for k^ = 0 for T < i' cr, and k"= 0
for t<t^ r .

-*s£ n
(10-162)
(10-163)

The instantaneous porosity is given by:
(10-164)

where <j) 0 is the initial porosity.
The instantaneous permeability is estimated by means of the modified
Kozeny-Carman equation (see Chapter 5 for derivation).

- I (10-165)