HR: 1340h
AN: H23C-1512    [Abstracts]
TI: Evaluation of the Effects of Cementation on Specific Storage of Granular Porous Media Using Discrete Element Models
AU: * Plourde, K E
EM: kplourde@geo.umass.edu
AF: University of Massachusetts - Amherst, Geoscience Department, Morrill Science Center, 611 North Pleasant Street, Amherst, MA 01003, United States
AU: Boutt, D F
EM: dboutt@geo.umass.edu
AF: University of Massachusetts - Amherst, Geoscience Department, Morrill Science Center, 611 North Pleasant Street, Amherst, MA 01003, United States
AU: Goodwin, L B
EM: laurel@geology.wisc.edu
AF: University of Wisconsin - Madison, Department of Geology and Geophysics University of Wisconsin - Madison 1215 W. Dayton St., Madison, WI 53706, United States
AU: Buchheit, T E
EM: tebuchh@sandia.gov
AF: Sandia National Laboratories, MS 0751, Albuquerque, NM 87123-0751, United States
AB: In recent years, population growth, climate change and surface water contamination have resulted in increased development of deep groundwater resources. As this trend continues, quantitative data of aquifer properties (i.e. specific storage) will be crucial for ensuring the sustainability of groundwater resources. Specific storage is the volume of water expelled due to the compressibility of the surrounding granular skeleton. The compressibility is believed to be controlled by the microscale properties of the surrounding granular skeleton (e.g. grain size, shape and mineralogy) and cementation. In general, cementation is assumed to reduce specific storage by reducing compressibility. However, data which adequately quantifies the relationship between cementation and storage does not exist due to unknown variations in mineralogy, amount and distribution of the cement. The goal of this research is to address this problem by quantifying the effects of cementation of granular porous media on specific storage using discrete-based numerical models. We modeled the modification of specific storage by varying microscale parameters (cement stiffness and percent of cementation) in a series of discrete element models (DEM). Modifications to microscale properties produce bulk-scale responses that are represented in a series of stress/strain curves for each model. The stress/strain curves are used to determine the stiffness for each model and to calculate percent of change in specific storage as a function of the microscale properties. Additionally, we are fabricating analog granular assemblages which will be used to better understand fluid storage in weakly cemented clastic materials. The assemblages will be used to evaluate the differences between natural and synthetic systems and to improve and interpret the DEM models. Preliminary results suggest that cementation has a strong control on the elastic storage properties of cemented granular media. We present results which quantify the proportion of cement needed to effectively reduce the specific storage. We anticipate being able to use the bulk-scale results from the DEM models as an input parameter for continuum-based coupled fluid-solid deformation models. The coupled models will allow us to further investigate elastic and inelastic poroelastic properties, (specific storage and aquifer compaction, respectively), with implications for carbon sequestration during which reactive transport (i.e. precipitation) is assumed to be important for fluid storage.
DE: 1828 Groundwater hydraulics
SC: Hydrology [H]
MN: 2007 Fall Meeting