Page 194 - Reservoir Formation Damage

176 Reservoir Formation Damage

Scale Formation and Dissolution at the Pore Surface

The rate of scale formation at the pore surface can be expressed
similarly to crystal growth. The pore volume relates to the diameter of
an equivalent spherical shape pore space by (Civan, 1996):

(9-30)

indicating that

Thus, the pore surface relates to the porosity according to:

2/3
(9-32)

3
and are some shape factors and C 5=C 4/C^ . The porosity of
C 3 C 4
the solid porous matrix can be expressed as a sum of the instantaneous
porosity, <|>, and the pore space occupied by the scales, <{> 5, as:

4>r=4> + <l>, (9-33)

Therefore, the mass of the scale formed over the pore surface is given by

= PA = (9-34)

Therefore, substituting Eqs. 9-32 and 9-34 into Eq. 9-23 yields (Civan,
1996):

(9-35)

subject to

(9-36)

where