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Reactive Transport Modeling of the Enhancement of Density-Driven CO2 Convective Mixing in Carbonate Aquifers and its Potential Implication on Geological Carbon Sequestration.

Islam A, Sun AY, Yang C - Sci Rep (2016)

Bottom Line: We study the convection and mixing of CO2 in a brine aquifer, where the spread of dissolved CO2 is enhanced because of geochemical reactions with the host formations (calcite and dolomite), in addition to the extensively studied, buoyancy-driven mixing.The nonlinear convection is investigated under the assumptions of instantaneous chemical equilibrium, and that the dissipation of carbonate rocks solely depends on flow and transport and chemical speciation depends only on the equilibrium thermodynamics of the chemical system.Early saturation of the reservoir can have negative impact on CO2 sequestration.

View Article: PubMed Central - PubMed

Affiliation: Bureau of Economic Geology, The University of Texas at Austin, TX, USA.

ABSTRACT
We study the convection and mixing of CO2 in a brine aquifer, where the spread of dissolved CO2 is enhanced because of geochemical reactions with the host formations (calcite and dolomite), in addition to the extensively studied, buoyancy-driven mixing. The nonlinear convection is investigated under the assumptions of instantaneous chemical equilibrium, and that the dissipation of carbonate rocks solely depends on flow and transport and chemical speciation depends only on the equilibrium thermodynamics of the chemical system. The extent of convection is quantified in term of the CO2 saturation volume of the storage formation. Our results suggest that the density increase of resident species causes significant enhancement in CO2 dissolution, although no significant porosity and permeability alterations are observed. Early saturation of the reservoir can have negative impact on CO2 sequestration.

No MeSH data available.


Change in porosity (Ra = 10,000, heterogeneous formation).
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f10: Change in porosity (Ra = 10,000, heterogeneous formation).

Mentions: Figure 10 displays porosity changes, based on volume fraction deviations, for the case of Ra = 10,000 and heterogeneous reservoir. Though dissolution observed has significantly been boosted by the reactions, maximum porosity alteration until the reservoir becomes CO2 saturated is only 0.02%. This slight increase is almost negligible and cannot affect hydrodynamics of the system by any means. By using porosity-permeability relation29, , respective permeability change is 0.06% which is also too small to distable fluid flow further.


Reactive Transport Modeling of the Enhancement of Density-Driven CO2 Convective Mixing in Carbonate Aquifers and its Potential Implication on Geological Carbon Sequestration.

Islam A, Sun AY, Yang C - Sci Rep (2016)

Change in porosity (Ra = 10,000, heterogeneous formation).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4837360&req=5

f10: Change in porosity (Ra = 10,000, heterogeneous formation).
Mentions: Figure 10 displays porosity changes, based on volume fraction deviations, for the case of Ra = 10,000 and heterogeneous reservoir. Though dissolution observed has significantly been boosted by the reactions, maximum porosity alteration until the reservoir becomes CO2 saturated is only 0.02%. This slight increase is almost negligible and cannot affect hydrodynamics of the system by any means. By using porosity-permeability relation29, , respective permeability change is 0.06% which is also too small to distable fluid flow further.

Bottom Line: We study the convection and mixing of CO2 in a brine aquifer, where the spread of dissolved CO2 is enhanced because of geochemical reactions with the host formations (calcite and dolomite), in addition to the extensively studied, buoyancy-driven mixing.The nonlinear convection is investigated under the assumptions of instantaneous chemical equilibrium, and that the dissipation of carbonate rocks solely depends on flow and transport and chemical speciation depends only on the equilibrium thermodynamics of the chemical system.Early saturation of the reservoir can have negative impact on CO2 sequestration.

View Article: PubMed Central - PubMed

Affiliation: Bureau of Economic Geology, The University of Texas at Austin, TX, USA.

ABSTRACT
We study the convection and mixing of CO2 in a brine aquifer, where the spread of dissolved CO2 is enhanced because of geochemical reactions with the host formations (calcite and dolomite), in addition to the extensively studied, buoyancy-driven mixing. The nonlinear convection is investigated under the assumptions of instantaneous chemical equilibrium, and that the dissipation of carbonate rocks solely depends on flow and transport and chemical speciation depends only on the equilibrium thermodynamics of the chemical system. The extent of convection is quantified in term of the CO2 saturation volume of the storage formation. Our results suggest that the density increase of resident species causes significant enhancement in CO2 dissolution, although no significant porosity and permeability alterations are observed. Early saturation of the reservoir can have negative impact on CO2 sequestration.

No MeSH data available.