Heterogeneity-enhanced gas phase formation in shallow aquifers during leakage of CO₂-saturated water from geologic sequestration sites

TY - JOUR

T1 - Heterogeneity-enhanced gas phase formation in shallow aquifers during leakage of CO2-saturated water from geologic sequestration sites

AU - Plampin, Michael R.

AU - Lassen, Rune Nørbæk

AU - Sakaki, Toshihiro

AU - Porter, Mark L.

AU - Pawar, Rajesh J.

AU - Jensen, Karsten Høgh

AU - Illangasekare, Tissa H.

PY - 2014/12/23

Y1 - 2014/12/23

N2 - A primary concern for geologic carbon storage is the potential for leakage of stored carbon dioxide (CO2) into the shallow subsurface where it could degrade the quality of groundwater and surface water. In order to predict and mitigate the potentially negative impacts of CO2 leakage, it is important to understand the physical processes that CO2 will undergo as it moves through naturally heterogeneous porous media formations. Previous studies have shown that heterogeneity can enhance the evolution of gas phase CO2 in some cases, but the conditions under which this occurs have not yet been quantitatively defined, nor tested through laboratory experiments. This study quantitatively investigates the effects of geologic heterogeneity on the process of gas phase CO2 evolution in shallow aquifers through an extensive set of experiments conducted in a column that was packed with layers of various test sands. Soil moisture sensors were utilized to observe the formation of gas phase near the porous media interfaces. Results indicate that the conditions under which heterogeneity controls gas phase evolution can be successfully predicted through analysis of simple parameters, including the dissolved CO2 concentration in the flowing water, the distance between the heterogeneity and the leakage location, and some fundamental properties of the porous media. Results also show that interfaces where a less permeable material overlies a more permeable material affect gas phase evolution more significantly than interfaces with the opposite layering.

AB - A primary concern for geologic carbon storage is the potential for leakage of stored carbon dioxide (CO2) into the shallow subsurface where it could degrade the quality of groundwater and surface water. In order to predict and mitigate the potentially negative impacts of CO2 leakage, it is important to understand the physical processes that CO2 will undergo as it moves through naturally heterogeneous porous media formations. Previous studies have shown that heterogeneity can enhance the evolution of gas phase CO2 in some cases, but the conditions under which this occurs have not yet been quantitatively defined, nor tested through laboratory experiments. This study quantitatively investigates the effects of geologic heterogeneity on the process of gas phase CO2 evolution in shallow aquifers through an extensive set of experiments conducted in a column that was packed with layers of various test sands. Soil moisture sensors were utilized to observe the formation of gas phase near the porous media interfaces. Results indicate that the conditions under which heterogeneity controls gas phase evolution can be successfully predicted through analysis of simple parameters, including the dissolved CO2 concentration in the flowing water, the distance between the heterogeneity and the leakage location, and some fundamental properties of the porous media. Results also show that interfaces where a less permeable material overlies a more permeable material affect gas phase evolution more significantly than interfaces with the opposite layering.

U2 - 10.1002/2014wr015715

DO - 10.1002/2014wr015715

M3 - Journal article

SN - 0043-1397

VL - 50

SP - 9251

EP - 9266

JO - Water Resources Research

JF - Water Resources Research

IS - 12

ER -