title: A 2.5D Reactive Transport Model for Fracture Alteration Simulation.
abstract: Understanding fracture alteration resulting from geochemical reactions is critical in predicting fluid migration in the subsurface and is relevant to multiple environmental challenges. Here, we present a novel 2.5D continuum reactive transport model that captures and predicts the spatial pattern of fracture aperture change and the development of an altered layer in the near-fracture region. The model considers permeability heterogeneity in the fracture plane and updates fracture apertures and flow fields based on local reactions. It tracks the reaction front of each mineral phase and calculates the thickness of the altered layer. Given this treatment, the model is able to account for the diffusion limitation on reaction rates associated with the altered layer. The model results are in good agreement with an experimental study in which a CO2-acidified brine was injected into a fracture in the Duperow Dolomite, causing dissolution of calcite and dolomite that result in the formation of a preferential flow channel and an altered layer. With an effective diffusion coefficient consistent with the experimentally observed porosity of the altered layer, the model captures the progressive decrease in the dissolution rate of the fast-reacting mineral in the altered layer.
authors.affiliation: Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Hang
authors.initials: H
authors.lastname: Deng
authors.affiliation: Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Sergi
authors.initials: S
authors.lastname: Molins
authors.affiliation: Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Carl
authors.initials: C
authors.lastname: Steefel
authors.affiliation: Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.|Earth and Planetary Science, University of California , Berkeley, Berkeley, California 94720, United States.
authors.forename: Donald
authors.initials: D
authors.lastname: DePaolo
authors.affiliation: Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Marco
authors.initials: M
authors.lastname: Voltolini
authors.affiliation: Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Li
authors.initials: L
authors.lastname: Yang
authors.affiliation: Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Ajo-Franklin
mesh_terms: D004058:Diffusion; D008903:Minerals; D008962:Models, Theoretical; D010539:Permeability; D016062:Porosity
chemical_list: D008903:Minerals