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

• 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
• Chủ đề: 1. 01 coal, lignite, and peat; 2. Geological carbon storage; 3. Imbibition; 4. Micromodel; 5. Pore characteristics

Tóm tắt

 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<
 sub>
 2<
 /sub>
  (scCO<
 sub>
 2<
 /sub>
 ) and coupled scCO<
 sub>
 2<
 /sub>
  dissolution and water flow, i.e., scCO<
 sub>
 2<
 /sub>
  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<
 sub>
 2<
 /sub>
  to establish a stable scCO<
 sub>
 2<
 /sub>
  saturation. DI water was then injected at different rates with <
 em>
 logC<
 sub>
 a<
 /sub>
 <
 /em>
  (the capillary number) ranging from -6.56 to -4.34. Results show that bypass of scCO<
 sub>
 2<
 /sub>
  by displacing water is the dominant mechanism contributing to the residual CO<
 sub>
 2<
 /sub>
  trapping, triggered by heterogeneity in pore characteristics or pore-scale scCO<
 sub>
 2<
 /sub>
 -water distribution. Bypass can be enhanced by pore heterogeneity or reduced by increasing transverse permeability, resulting in relatively low (<
 2% of CO<
 sub>
 2<
 /sub>
  solubility) or high (9?13% of CO<
 sub>
 2<
 /sub>
  solubility) dissolved CO<
 sub>
 2<
 /sub>
  concentration in displacing water. The overall dissolution of residual scCO<
 sub>
 2<
 /sub>
  increases with decreasing <
 em>
 C<
 sub>
 a<
 /sub>
 <
 /em>
 , and approaches to their solubility at low <
 em>
 C<
 sub>
 a<
 /sub>
 <
 /em>
  value with sufficient residence time. This main trend is similar to a capillary desaturation curve that represents the relationship between the residual saturation and <
 em>
 C<
 sub>
 a<
 /sub>
 <
 /em>
 . Spatially, dissolution initiates along the boundary of bypassed scCO<
 sub>
 2<
 /sub>
  cluster(s) in a non-equilibrium manner, and the coupling of water flow and dissolution occurs which fragments the bypassed scCO<
 sub>
 2<
 /sub>
  clusters and enhance scCO<
 sub>
 2<
 /sub>
  dissolution.