Page 353 - Reservoir Formation Damage

Inorganic Scaling and Geochemical Formation Damage 333

compact layer
of adsorbed ions

bulk solution

DISTANCED (meters)
0-plane
(mineral surface)
p*-plane
(electrolyte adsorption)

Figure 13-2. Triple-layer description of the potential vs. distance from the
mineral surface (Reprinted from Journal of Computers and Geosciences, Vol.
24, Sahai, N., & Sverjensky, D. A., "GEOSURF: A Computer Program for
Modeling Adsorption on Mineral Surfaces from Aqueous Solution," pp. 853-
873, ©1998, with permission from Elsevier Science).

ing exchange sites," but this effect has not been taken into account in
most reported studies. In Eq. 13-15, <j) and p^ denote the porosity and
the grain density of the rock, respectively. Represent the exchange sites
by a, the total number of different exchange sites by N a, an exchange
site of type ot with unit charge by E a, the i' h cation species with valence
Zi by S f, and the concentration of the i th species attached to the exchange
sites a by C™, expressed in moles per unit bulk volume. Lichtner (1985)
then describes the chemical reactions at mineral surfaces by

(13-16)