Monday,
November 14, 2011
6:00 - 7:30 pm
Pellissippi State Technical Community College
10915 Hardin
Valley Road, Knoxville
J.L Goins Administration Building, Cafeteria Annex
NOVEMBER
PRESENTATION
Geological
Storage of Carbon Dioxide:
Implementation, Simulations, and Impacts
By
Chu-Lin Cheng
and Dr. Ed Perfect
Department of Earth and Planetary Sciences
University of Tennessee, Knoxville
Abstract
Anthropogenic emissions of CO2 are rapidly
changing the gaseous composition of the atmosphere and
contributing to global climate change. Capture and storage of CO2
in the subsurface is currently considered to be the most
promising mitigation strategy. The main geologic storage options
are confined saline aquifers, coal beds, depleted oil reservoirs,
shales, and other reactive rocks that facilitate carbonate
precipitation.
Mathematical models and numerical simulations are important tools
for evaluating the feasibility of geologic storage of CO2 and the
design and operation of future storage systems. Researchers need
petrophysical and geochemical parameters to evaluate the total
amount of carbon that can be stored in a particular rock
formation and to predict the redistribution of CO2 gas following
injection. In particular, point parameters for the van Genuchten (VG) equations
describing the functional relationships between capillary pressure, relative
saturation, and relative permeability are essential for modeling gas-liquid
displacements in porous media. Many simulations of the fate CO2 injected into
brine aquifers simply assume values of the VG parameters for typical conditions. In other cases, average
instead of point VG parameters, are employed due to their
relative ease of measurement in the laboratory. The use of
assumed or average VG parameters can result in significant
prediction errors, especially in the case of coarse-grained
sediments and fractured rocks. Such errors can impose great risks
and challenges to decision-making.
The presentation will start with an introduction to the carbon
problem. The mechanisms involved in carbon capture and storage
will be discussed, followed by evaluations of key petrophysical
parameters needed for numerical modeling. Forward numerical
simulations using the Subsurface Transport Over Multiple Phases
(STOMP) model will be employed to illustrate the magnitudes of
the errors in flow and transport predictions resulting from the
use of different values for one single VG parameter (m,
representing the pore size distribution). Model predictions
indicate that integrated carbon inventories after 10,000 days
(~27 years) range between -16% and +4.8% in the aqueous and gas
phases depending upon the choice of the m value.
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