InterPore2026

Structural barriers to complete homogenization and wormholing in dissolving porous and fractured rocks

21 May 2026, 09:20

15m

Oral Presentation (MS08) Mixing, dispersion and reaction processes across scales in heterogeneous and fractured media MS08

Speaker

Tomasz Szawełło (University of Warsaw)

Description

Dissolution in porous media and fractured rocks alters both the chemical composition of the fluid and the physical properties of the solid, with major implications for permeability evolution, injectivity, and long-term transport [1]. Depending on the balance between advection, diffusion, and surface reaction, reactive flow may enlarge pores uniformly, widen pre-existing channels, or trigger instabilities that form wormholes. The resulting patterns depend not only on the roughness of individual links (pore diameters or fracture apertures), but also on the underlying network topology and the distribution of path lengths—features that differ sharply between porous media and fracture networks.

We investigate these effects using three network models: a regular pore network (diamond lattice) with variability only in pore diameters, a disordered pore network (Delaunay lattice) with variability in both diameters and pore lengths [2], and a discrete fracture network [3] with heterogeneity in fracture apertures, lengths, and connectivity. Across all systems, we classify heterogeneity into link-scale (diameter/aperture), segment-scale (length), and network-scale (connectivity).

Dissolution is simulated over a broad range of effective Damköhler numbers and reaction–diffusion parameters, capturing uniform, channeling, and wormholing regimes. The evolution is quantified by a single metric—the flow focusing profile—which measures how many links are needed to carry a fixed fraction of the total flow along the system length [4]. This metric reveals a focusing front advancing from the inlet in the wormholing regime, a system-wide decrease in focusing under uniform dissolution, and nearly uniform amplification of pre-existing paths during channeling.

Our results show that, even when link-scale heterogeneity is largely erased, structural heterogeneity in path lengths and connectivity sets a hard lower bound on flow homogenization. Disordered pore networks and discrete fracture networks retain significant focusing even at low Damköhler numbers, implying that continuum models that assume complete homogenization under uniform dissolution may systematically underestimate the persistence of preferential flow paths in natural rocks.