Lawrence Berkeley National Laboratory, Report LBNL-36086
A TOUGH2 equation-of-state module
for the simulation of two-phase flow
of air, water, and a miscible gelling liquid
S. Finsterle, G. J. Moridis, and K. Pruess
Lawrence Berkeley National Laboratory, Earth Sciences Division
University of California, Berkeley, CA 94720
Abstract.
The injection of grout into the subsurface can be used to encapsulate contaminated regions
of an aquifer, or to form underground barriers for the isolation of contaminant sources and to
prevent the spreading of existing plumes. This requires identifying grouts, or barrier fluids,
which when injected into the subsurface exhibit a large increase in viscosity and eventually
solidify, sealing the permeable zones in the aquifer. Simulation and modeling analysis are
indispensable tools for designing the injection and predicting the performance of the barrier.
In order to model flow and transport in such systems, the thermophysical properties of the
fluid mixtures have to be provided, and the governing mass- and energy-balance equations
for multiphase flow in porous media have to be solved numerically. The equation-of-state
module EOS11 described herein is an extension of the EOS7 module of the TOUGH2 code
for flow of saline water and air. In our modeling approach, the chemical grout is treated as a
miscible fluid the viscosity of which is a function of time and concentration of the gelling
agent in the pore water. If a certain high viscosity is reached and the movement of the grout
plume ceases, the gel is assumed to solidify, leading to a new porous medium with changed
soil characteristics, i.e. reduced porosity and permeability, increased capillary strength for a
given water content, and changed initial saturation distribution.
(1.0 MB).
