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Abstract
\nThis study develops a one-dimensional analytical framework for CO₂ injection into saline aquifers containing multiple impurities and equilibrium reactions.
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Extending previous solutions limited to non-reactive, self-sharpening systems, the approach combines gas-injection theory, the method of characteristics, and tie-line analysis to describe multicomponent systems that may exhibit both shocks and non-tie-line rarefactions.
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The results show that impurities less volatile than CO₂, when initially dissolved in the formation brine, can produce non-self-sharpening behavior, whereas more volatile impurities tend to maintain self-sharpening displacement paths.
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Equilibrium reactions are incorporated through apparent equilibrium ratios (K-values), which account for the distribution of a component among its aqueous conjugate species and depend primarily on brine pH. This formulation enables the analytical framework developed for non-reactive systems to be extended to reactive transport, allowing prediction of impurity propagation, gas saturation, composition, and pH.
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The results further demonstrate that geochemical reactions can modify impurity dissolution and shock velocities, particularly for reactive species such as SO₂, while leaving the propagation of non-reactive components largely unchanged.
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Analytically calculated profiles are useful for benchmarking numerical simulations and understanding the different mechanisms that influence the numerical results.
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An example of such application is the near wellbore pH during cyclic injection of CO2-rich stream into aquifer, for the greensand project, where analytical solutions was used to validate numerical models, and provide insight for numerical setup.
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Abstract
\nThis study develops a one-dimensional analytical framework for CO₂ injection into saline aquifers containing multiple impurities and equilibrium reactions.
\n\n
Extending previous solutions limited to non-reactive, self-sharpening systems, the approach combines gas-injection theory, the method of characteristics, and tie-line analysis to describe multicomponent systems that may exhibit both shocks and non-tie-line rarefactions.
\n\n
The results show that impurities less volatile than CO₂, when initially dissolved in the formation brine, can produce non-self-sharpening behavior, whereas more volatile impurities tend to maintain self-sharpening displacement paths.
\n\n
Equilibrium reactions are incorporated through apparent equilibrium ratios (K-values), which account for the distribution of a component among its aqueous conjugate species and depend primarily on brine pH. This formulation enables the analytical framework developed for non-reactive systems to be extended to reactive transport, allowing prediction of impurity propagation, gas saturation, composition, and pH.
\n\n
The results further demonstrate that geochemical reactions can modify impurity dissolution and shock velocities, particularly for reactive species such as SO₂, while leaving the propagation of non-reactive components largely unchanged.
\n\n
Analytically calculated profiles are useful for benchmarking numerical simulations and understanding the different mechanisms that influence the numerical results.
\n\n
An example of such application is the near wellbore pH during cyclic injection of CO2-rich stream into aquifer, for the greensand project, where analytical solutions was used to validate numerical models, and provide insight for numerical setup.
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