Page 70 - Reservoir Formation Damage

Petrography and Texture of Petroleum-Bearing Formations 53

a = A/Vp = 6/D (3-4)

The expressions given above for a spherical shape can be corrected
for irregular pore space, respectively, as (Civan, 1996):

=
V P (3-5)

= C 2D 3 (3-6)

2 3
2
A = C 3D = C 4(|) / (3-7)
a = C 5/D (3-8)

where C l,C 2,...,C 5 are some empirical shape factors.
Similarly, for the spherical idealization of a particle, the specific
surface defined as the contact surface per volume sphere is given by:

(3-9)

This can be corrected for irregular particle shape as:

(3-10)

where C 6 is a shape factor.

Area Open for Flow

Areosity or areal porosity is the fractional area of the bulk porous
media open for flow (Liu and Masliyah, 1996). Liu and Masliyah (1996)
point out that, frequently, the areal porosity has been taken equal to the
volumetric porosity of porous media.

A f=* (3-11)

They emphasize that Equation 3-11 performs well for models con-
sidering a bundle of straight hydraulic flow pathways and nonconnecting
constricted pathways. Whereas, for isotropic porous media, Liu et al.
(1994) recommend that the areal porosity should be estimated as:

(3-12)