Dissolved CO2 stabilizes dissolution front and increases breakthrough porosity of natural porous materials
arXiv:1704.01061 · doi:10.1021/acs.est.7b02157
Abstract
When reactive fluids flow through a dissolving porous medium, conductive channels form, leading to fluid breakthrough. This phenomenon is important in geologic carbon storage, where the dissolution of CO2 in water increases the acidity and produce microstructures significantly different from those in an intact reservoir. We demonstrate the controlling mechanism for the dissolution patterns in natural porous materials. This was done using numerical simulations based on high resolution digital models of North Sea chalk. We tested three model scenarios, and found that aqueous CO2 dissolve porous media homogeneously, leading to large breakthrough porosity. In contrast, CO2-free solution develops elongated convective channels in porous media, known as wormholes, and resulting in small breakthrough porosity. We further show that a homogeneous dissolution pattern appears because the sample size is smaller than the theoretical size of a developing wormhole. The result indicates that the presence of dissolved CO2 expands the reactive subvolume of a porous medium, and thus enhances the geochemical alteration of reservoir structures and might undermine the sealing integrity of caprocks when minerals dissolve.
arXiv comment40 pages, 9 figures
References in corpus (2)
Cited by in corpus (6)
- Direct observation of coupled geochemical and geomechanical impacts on chalk microstructural evolution under elevated CO2 pressure. Part I
- Reactive infiltration instability amplifies the difference between geometric and reactive surface areas in natural porous materials
- Retraction of dissolution front in natural porous media
- Temporal pattern of entropy production induced by reactive infiltration instability in natural porous media
- Momentary increase in reactive surface area in dissolving carbonate
- Path selection during wormhole growth