Reactive transport modeling in fractures and two-phase flow
Abstract
This study presents a mathematical model to simulate hydrodynamics and
fluid-mineral reactions in a fracture within permeable media. Fluid convection, diffusion
and precipitation / dissolution (PD) reactions inside a finite space are solved
as a simplified representation of natural fracture mineralization. The problem involves
mass transfer within the fluid accompanied by chemical reaction at the fracture
surface. Mass-conservation equations for components in the fluid are solved,
and these are coupled with chemical reaction at the fracture surface. The intent
of this model is to show the time evolution of fracture aperture shrinkage patterns
caused by the calcite cementation. We present the aperture width distribution along
the fracture. In this study, we consider the precipitate as porous media and allow
porosity and permeability in the cement. Therefore, the calcite cementation completely
fills eventually.
As a second subject, the reactive transport model of CO2 sequestration in
aquifers is studied. Geologic formations are considered as a target for the sequesvi
tration ofCO2 from stationary sources such as power plants or large industrial facilities.
Deep saline aquifers have a large potential storage capacity for CO2 and they
are ubiquitous in sedimentary formations. CO2 can be sequestered in geologic formations
by three principal mechanisms: hydrodynamic trapping, solubility trapping
and mineral trapping. Mineral trapping is the most stable way of CO2 sequestration
in aquifers. Storage capacities of CO2 for each trapping mechanism are presented
using GEM, a commercial program from Computer Modeling Group Ltd. We also
present the anlaytical solutions for the miscible displacement and compare them
with the numerical results. Developing methods for increasing the mineral trapping
creates stable repositories of carbon dioxide and that decreases mobile hazards such
as leakage of CO2 to the surface.
Department
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