Page 168 - Reservoir Formation Damage
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150 Reservoir Formation Damage
Figure 8-4. Particles approaching a pore throat.
and
k, = 0 otherwise (8-16)
represents the critical time when the pore throats are first jammed
t cr
by particles.
This time is similar to the screen-factor. Himes et al. (1991) define
the screen-factor as:
A screen-factor value is the time for a given volume of a solution
to pass through a network of five lOO-U.S.-mesh screens stacked
together and normalized to the time taken for the carrier fluid alone
(usually water). A higher screen-factor value means less mobility
and poor injectivity. A value of one indicates equal mobility to the
carrier fluid.
|3 is the pore throat to particle diameter ration given by (see Figure S-4):
(8-17)
P = D t/D p
and P cr is the critical value below which pore throat blocking can occur.
One of the factors affecting the particle migration through a pore throat
is the particle size relative to the pore throat size. The hydraulic tube
diameter is given by the Carman-Kozeny equation:
(8-18)