Multicomponent reactive transport in discrete fractures; I, Controls on reaction front geometry

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Authors:Steefel, Carl I.; Lichtner, Peter C.
Author Affiliations:Primary:
University of South Florida, Department of Geosciences, Tampa, FL, United States
Georgia Institute of Technology, United States
Southwest Research Institute, United States
Volume Title:Reactive transport modeling of natural systems
Volume Authors:Steefel, Carl I., editor; Van Cappellen, Philippe
Source:Journal of Hydrology, 209(1-4), p.186-199; Geological Society of America, 1996 annual meeting , symposium on Application of reactive transport modeling to natural systems, Denver, CO, Oct. 1996, edited by Carl I. Steefel and Philippe Van Cappellen. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0022-1694
Publication Date:1998
Note:In English. 50 refs.; illus., incl. 4 tables
Summary:A multicomponent reactive transport model with mixed equilibrium and kinetic reactions is presented for a dual porosity system. The model is used to analyze alteration front geometry in discrete fractures and adjacent rock matrix. An analytical solution for a dual porosity system is used to verify the numerical model and to obtain an expression for mineral reaction front geometry under quasi-stationary state conditions. Both the analytical solution and numerical results suggest that the geometry of reaction fronts in a dual porosity system can be characterized by the sum of two dimensionless parameters: φD'/δv (φ = porosity, D' = effective diffusion coefficient in rock matrix, δ = fracture aperture, and v = fluid velocity in the fracture) and λm0fm = equilibration length scale in rock matrix and λ0f = equilibration length scale in the fracture in the absence of matrix diffusion). In the case where the system is surface reaction-controlled, the first dimensionless parameter, which is independent of the reaction rate constants, dominates. From an analysis of a system described by linear reaction rates, this parameter can be used to predict quasi-stationary state concentration profiles and the distribution of minerals along the length of a fracture based on the one-dimensional diffusion-reaction profile in the rock matrix bordering the fracture. Numerical simulations of a multi-component problem involving dedolomitization resulting from the infiltration of hyperalkaline groundwater demonstrate that the dimensionless parameter φD'/δv applies in more complicated multicomponent systems as well. This result suggests that field observations of matrix alteration perpendicular to the fracture may be used to predict mineralization along the fracture itself. Abstract Copyright (1998) Elsevier, B.V.
Subjects:Carbonatization; Chemical reactions; Controls; Data processing; Dedolomitization; Diagenesis; Digital simulation; Dolomitization; Fractured materials; Fractures; Geochemistry; Ground water; Hydrochemistry; Kinetics; Mass transfer; Metasomatism; Numerical models; Phase equilibria; Pollution; Radioactive waste; Solute transport; Underground disposal; Wall-rock alteration; Waste disposal; Water-rock interaction
Record ID:1999002949
Copyright Information:GeoRef, Copyright 2018 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands
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