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CO 2 Dissolution Trapping Rates in Heterogeneous Porous Media
Author(s) -
Gilmore K. A.,
Neufeld J. A.,
Bickle M. J.
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl087001
Subject(s) - dissolution , advection , permeability (electromagnetism) , trapping , porous medium , porosity , carbon dioxide , aquifer , diffusion , geology , materials science , mineralogy , chemical engineering , chemistry , thermodynamics , groundwater , geotechnical engineering , ecology , biochemistry , physics , organic chemistry , membrane , biology , engineering
The rate of carbon dioxide (CO 2 ) dissolution in saline aquifers is the least well‐constrained of the secondary trapping mechanisms enhancing the long‐term security of geological carbon storage. CO 2 injected into a heterogeneous saline reservoir will preferentially travel along high permeability layers increasing the CO 2 ‐water interfacial area which increases dissolution rates. We provide a conservative, first‐principles analysis of the quantity of CO 2 dissolved and the rate at which free‐phase CO 2 propagates in layered reservoirs. At early times, advection dominates the propagation of CO 2 . This transitions to diffusion dominated propagation as the interfacial area increases and diffusive loss slows propagation. As surrounding water‐filled layers become CO 2 saturated, propagation becomes advection dominated. For reservoirs with finely bedded strata, ∼ 10% of the injected CO 2 can dissolve in a year. The maximum fraction of CO 2 that dissolves is determined by the volumetric ratio of water in low permeability layers and CO 2 in high permeability layers.