Coupled supercritical CO2 dissolution and water flow in pore-scale micromodels [electronic resource]

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Ngôn ngữ: eng

Ký hiệu phân loại: 666.9 Masonry adhesives

Thông tin xuất bản: Washington, D.C. : Oak Ridge, Tenn. : United States. Dept. of Energy. Office of Science ; Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2018

Mô tả vật lý: Size: p. 54-69 : , digital, PDF file.

Bộ sưu tập: Metadata

ID: 267721

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Dissolution trapping is one of the most crucial mechanisms for geological carbon storage (GCS). Recent laboratory and field experiments have shown non-equilibrium dissolution of supercritical CO
2
(scCO
2
) and coupled scCO
2
dissolution and water flow, i.e., scCO
2
dissolution at local pores/pore throats creating new water-flow paths, which in turn enhance dissolution by increased advection and interfacial area. Yet, the impacts of pore-scale characteristics on these coupled processes have not been investigated. In this study, imbibition and dissolution experiments were conducted under 40�C and 9 MPa using a homogeneous/isotropic hexagonal micromodel, two homogeneous elliptical micromodels with low or high anisotropy, and a heterogeneous sandstone-analog micromodel. The four micromodels, initially saturated with deionized (DI)-water, were drained by injecting scCO
2
to establish a stable scCO
2
saturation. DI water was then injected at different rates with 
logC
a

(the capillary number) ranging from -6.56 to -4.34. Results show that bypass of scCO
2
by displacing water is the dominant mechanism contributing to the residual CO
2
trapping, triggered by heterogeneity in pore characteristics or pore-scale scCO
2
-water distribution. Bypass can be enhanced by pore heterogeneity or reduced by increasing transverse permeability, resulting in relatively low (<
2% of CO
2
solubility) or high (9?13% of CO
2
solubility) dissolved CO
2
concentration in displacing water. The overall dissolution of residual scCO
2
increases with decreasing 
C
a

, and approaches to their solubility at low 
C
a

value with sufficient residence time. This main trend is similar to a capillary desaturation curve that represents the relationship between the residual saturation and 
C
a

. Spatially, dissolution initiates along the boundary of bypassed scCO
2
cluster(s) in a non-equilibrium manner, and the coupling of water flow and dissolution occurs which fragments the bypassed scCO
2
clusters and enhance scCO
2
dissolution.

1. 01 coal, lignite, and peat
2. Geological carbon storage
3. Imbibition
4. Micromodel
5. Pore characteristics

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Coupled supercritical CO<sub>2</sub> dissolution and water flow in pore-scale micromodels [electronic resource]