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Morten R. Kristensen, Margot
Gerritsen, Per G. Thomsen, Michael L. Michelsen and Erling H. Stenby
An Equation-of-State
Compositional In-Situ Combustion Model: A Study of Phase Behavior
Sensitivity
Transport in
Porous Media, 76(2):214-241, 2009.
Abstract
To facilitate the study of
reactive-compositional porous media processes we develop a virtual
kinetic cell (single-cell model) as well as a vitual combustion tube
(one-dimensional model). Both models are fully compositional based
on an equation of state. We employ the models to study phase
behavior sensitivity for in-situ combustion, a thermal oil recovery
process.
For the one-dimensional model we first study the sensitivity to
numerical discretization errors and provide grid density guidelines
for proper resolution of in-situ combustion behavior. A critical
condition for success of in-situ combustion processes is the
formation and sustained propagation of a high-temperature combustion
front. Using the models developed we study the impact of phase
behavior on ignition/extinction dynamics as a function of the
operating conditions. We show that when operating close to
ignition/extinction branches, a change of phase behavior model will
shift the system from a state of ignition to a state of extinction
or vice versa. For both the rigorous equation of state based and a
simplified, but commonly used, K-value based phase behavior
description we identify areas of operating conditions which lead to
ignition. For a particular oil we show that the simplified approach
overestimates the required air injection rate for sustained front
propagation by 17% compared to the equation of state based approach.
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