InterPore2026

Pore-scale modeling of Ostwald ripening: Comparison with a Percolation without Trapping Model

19 May 2026, 09:50

1h 30m

Poster Presentation (MS09) Pore-Scale Physics and Modeling Poster

Speaker

Ademola Adebimpe

Description

The accurate prediction of multiphase flow in porous media underlies key subsurface energy applications such as geological carbon sequestration (GCS) and underground hydrogen storage (UHS). Ostwald ripening — the diffusion-driven dissolution of small gas ganglia and redeposition onto larger ones - strongly modifies phase connectivity, yet classical models are limited to unconfined, equilibrium systems. Recently, Adebimpe et al. (2024) recast equilibrium two-phase displacement as percolation without trapping, demonstrating that conventional measurements overestimate capillary trapping by 20–25 \% when ripening is ignored. Here, we extend this framework by developing a time-dependent pore-network model that couples transient mass transfer, capillary pressure heterogeneity, and realistic pore-throat geometries to capture the dynamic evolution of gas clusters during Ostwald ripening. The model is applied to Bentheimer sandstone to study Ostwald ripening after imbibition to residual gas saturation. In addition to including time dependence, unlike the equilibrium model, both imbibition (shrinkage) and drainage (growth) events are allowed. The model tracks event statistics, capillary pressure equilibration, cluster volume distributions, and spatial saturation profiles over 30 days. While the volume-weighted average capillary pressure is constant, there is a rapid initial decline in average number-weighted cluster pressure (from ~4200 Pa to ~2200 Pa) and a shift in cluster size distributions toward fewer, larger ganglia, consistent with pore-scale imaging studies. Pore and throat occupancy analysis reveal persistent gas trapping in larger pore spaces. Since growth is by drainage, the pore-scale configuration of fluid is different from that predicted by a percolation-without-trapping model that only allows imbibition displacements. The implications of this for the interpretation of experimental results are discussed.