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Title: Fluid Flow, Solute Mixing and Precipitation In Porous Media

Abstract

No abstract prepared.

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Idaho National Laboratory (INL), Idaho Falls, ID
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
924705
Report Number(s):
CONF/ERSD2007-1020913
R&D Project: ERSD 1020913; TRN: US200809%%330
DOE Contract Number:
AC07-05ID14517; AC06-76RLO1830
Resource Type:
Conference
Resource Relation:
Conference: Annual Environmental Remediation Science Program (ERSP) principal Investigator Meeting, April 16-19, 2007, Lansdowne, VA
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 54 ENVIRONMENTAL SCIENCES; POROUS MATERIALS; FLUID FLOW; PRECIPITATION; SOLUTES; MIXING; FLUID MECHANICS

Citation Formats

George D. Redden, Yoshiko Fujita, Yi-Lin Fang, T.D. Scheibe, A.M. Tartakovsky, Mikala Beig, Joanna Taylor, Robert W. Smith, Michael M. Reddy, and Shelly Kelly. Fluid Flow, Solute Mixing and Precipitation In Porous Media. United States: N. p., 2007. Web.
George D. Redden, Yoshiko Fujita, Yi-Lin Fang, T.D. Scheibe, A.M. Tartakovsky, Mikala Beig, Joanna Taylor, Robert W. Smith, Michael M. Reddy, & Shelly Kelly. Fluid Flow, Solute Mixing and Precipitation In Porous Media. United States.
George D. Redden, Yoshiko Fujita, Yi-Lin Fang, T.D. Scheibe, A.M. Tartakovsky, Mikala Beig, Joanna Taylor, Robert W. Smith, Michael M. Reddy, and Shelly Kelly. Thu . "Fluid Flow, Solute Mixing and Precipitation In Porous Media". United States. doi:. https://www.osti.gov/servlets/purl/924705.
@article{osti_924705,
title = {Fluid Flow, Solute Mixing and Precipitation In Porous Media},
author = {George D. Redden and Yoshiko Fujita and Yi-Lin Fang and T.D. Scheibe and A.M. Tartakovsky and Mikala Beig and Joanna Taylor and Robert W. Smith and Michael M. Reddy and Shelly Kelly},
abstractNote = {No abstract prepared.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Apr 19 00:00:00 EDT 2007},
month = {Thu Apr 19 00:00:00 EDT 2007}
}

Conference:
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  • Reactions that lead to the formation of mineral precipitates, colloids or growth of biofilms in porous media often depend on the molecular-level diffusive mixing. For example, for the formation of mineral phases, exceeding the saturation index for a mineral is a minimum requirement for precipitation to proceed. Solute mixing frequently occurs at the interface between two solutions each containing one or more soluble reactants, particularly in engineered systems where contaminant degradation or modification or fluid flow are objectives. Although many of the fundamental component processes involved in the deposition or solubilization of solid phases are reasonably well understood, including precipitationmore » equilibrium and kinetics, fluid flow and solute transport, the deposition of chemical precipitates, biofilms and colloidal particles are all coupled to flow, and the science of such coupled processes is not well developed. How such precipitates (and conversely, dissolution of solids) are distributed in the subsurface along flow paths with chemical gradients is a complex and challenging problem. This is especially true in systems that undergo rapid change where equilibrium conditions cannot be assumed, particularly in subsurface systems where reactants are introduced rapidly, compared to most natural flow conditions, and where mixing fronts are generated. Although the concept of dispersion in porous media is frequently used to approximate mixing at macroscopic scales, dispersion does not necessarily describe pore-level or molecular level mixing that must occur for chemical and biological reactions to be possible. An example of coupling between flow, mixing and mineral precipitation, with practical applications to controlling fluid flow or contaminant remediation in subsurface environments is shown in the mixing zone between parallel flowing solutions. Two- and three-dimensional experiments in packed-sand media were conducted where solutions containing calcium and carbonate ions came into contact along a parallel flow boundary and mixed by dispersion and diffusion. The result is the propagation of calcium carbonate precipitates along the solution-solution boundary in the direction of flow. As carbonate precipitates fill the pore space mixing of the two solutions is restricted and therefore precipitation, flow, and transport are coupled. The distribution of carbonate phases is a complex interaction involving precipitation and dissolution kinetics, which are functions of pore-scale saturation indices and solute ratios, heterogeneous vs. homogeneous nucleation and growth mechanisms and changes in porosity and flow. Experimental and modeling results illustrate challenges in understanding the macroscopic and microscopic phenomena that depend on solute mixing, the relevance of molecular and pore-scale processes to the macroscopic behavior, and potential impact on metal mobility in porous media. Mineral precipitation and changes in porosity are simulated at the pore-scale using the Smooth Particle Hydrodynamics method. Macroscopic simulations were performed using discretized, continuum-scale modeling with parameterization representing macroscopic media properties. One of the modeling goals is to use pore-scale simulations to provide the basis for parameterization of macroscopic (more practical) model predictions.« less
  • Synchrotron X-ray microtomography was used to track the spatiotemporal evolution of mineral precipitation and the consequent alteration of the pore structure. Column experiments were conducted by injecting CaCl2 and NaHCO3 solutions into granular porous media either as a premixed supersaturated solution (external mixing) or as separate solutions that mixed within the specimen (internal mixing). The two mixing modes produced distinct mineral growth patterns. While internal mixing promoted transverse heterogeneity with precipitation at the mixing zone, external mixing favored relatively homogeneous precipitation along the flow direction. The impact of precipitation on pore water flow and permeability was assessed via 3-D flowmore » simulations, which indicated anisotropic permeability evolution for both mixing modes. Under both mixing modes, precipitation decreased the median pore size and increased the skewness of the pore size distribution. Such similar pore-scale evolution patterns suggest that the clogging of individual pores depends primarily on local supersaturation state and pore geometry.« less
  • The transport of chemicals through solid waste disposal piles presents a potential source of surface and groundwater contamination. In an effort to determine the scope of the potential hazard, many laboratory tests have been devised and used on the waste materials. A prerequisite for such a test would be that it yields reproducible results. An added advantage, however, would be that the mechanisms of leachate generation in the test have some resemblance to those in the field.
  • A mathematical model has been developed for simulating the one-dimensional transport of solutes in a saturated porous medium. The numerical model, GCHEMFLOW (geochemistry and fluid flow), considers dispersion/diffusion, convection, ion exchange, the formation of complexes in the aqueous phase, the dissociation of water, competitive adsorption of organics, and the biodegradation of selected organics. This model was developed to predict the extent of process liabilities of in situ energy extraction. The geochemical equilibrium equations are solved simultaneously with the partial differential equations (PDEs) describing the convection/diffusion behavior of the solutes and the PDE for saturated flow of water through porous media.more » The resulting system of algebraic and differential equations are discretized with respect to space and integrated across time using Newton-Raphson iteration with variable time stepping. The discretization is done implicitly so that the unknown variables - pressure, velocity, and species concentrations - are determined simultaneously throughout the reservoir at a future time. A consistent set of model compounds consisting of both organic and inorganic species is selected for debugging and evaluating numerical solution technique characteristics. This report details the mathematical representations of the models fundamental equations, the numerical techniques used for obtaining solutions, the necessary model input data, and the output from the model. 33 refs.« less