Page 355 - Reservoir Formation Damage

Inorganic Scaling and Geochemical Formation Damage 335

where Cf is the concentration of the i th species attached to the exchange
sites a expressed in moles per unit bulk volume. Because

(13-21)

(13-22)

then, (13-23)

Thus, Lichtner (1985) combined Eqs. 13-19 and 20 into the following
convenient form by summing Eq. 13-20 over all the exchange sites a,
adding the resultant equation to Eq. 13-19, and eliminating the exchange
reaction rates by means of Eq. 13-23:

(13-24)

Geochemical Modeling
As stated by Plummer (1992)*: "Geochemical modeling attempts to
interpret and (or) predict chemical reactions of minerals, gases, and
organic matter with aqueous solutions in real or hypothetical water-rock
systems." Figure 13-3 by Bassett and Melchior (1990) outlines the basic
constituents and options of most geochemical models.
Plummer (1992)* classified the various geochemical modeling efforts
into four groups:

1. Aqueous speciation models for geochemical applications,
2. Inverse geochemical modeling techniques for interpreting observed
hydrochemical data,
3. Forward geochemical modeling techniques for simulating the chemi-
cal evolution of water-rock systems, and
4. Reaction-transport modeling for the coupling of geochemical reac-
tion modeling with equations describing the physics of fluid flow
and solute transport processes.
Brief descriptions of these models are presented in the following, accord-
ing to Plummer (1992).

* Reprinted from "Water-Rock Interaction," Proceedings of the 7th international symposium,
WRI-7, Park City, Utah, 13-18 July 1992 Kharaka, Y. K. & A. S. Maest (eds.), 90 5410
075 3, 1992, 25 cm, 1730 pp., 2 vols., EUR 209.00/US$246.00 GBP147. Please order
from: A. A. Balkema, Old Post Road, Brookfield, Vermont 05036 (telephone: 802-276-
3162; telefax: 802-276-3837; e-mail: info@ashgate.com).