-Pore connectivity is likely one of the most important factors affecting the permeability of reservoir rocks. Furthermore, connectivity effects are not restricted to materials approaching a percolation transition but can continuously and gradually occur in rocks undergoing geological processes such as mechanical and chemical diagenesis. In this study, we compiled sets of published measurements of porosity, permeability and formation factor, performed in samples of unconsolidated granular aggregates, in which connectivity does not change, and in two other materials, sintered glass beads and Fontainebleau sandstone, in which connectivity does change. We compared these data to the predictions of a Kozeny-Carman model of permeability, which does not account for variations in connectivity, and to those of Bernabé et al. (2010Bernabé et al. ( , 2011 ]. Both models agreed equally well with experimental data obtained in unconsolidated granular media. But, in the other materials, especially in the low porosity samples that had undergone the greatest amount of sintering or diagenesis, only Bernabé et al. model matched the experimental data satisfactorily. In comparison, predictions of the Kozeny-Carman model differed by orders of magnitude. The advantage of the Bernabé et al. model was its ability to account for a continuous, gradual reduction in pore connectivity during sintering or diagenesis. Although we can only speculate at this juncture about the mechanisms responsible for the connectivity reduction, we propose two possible mechanisms, likely to be active at different stages of sintering and diagenesis, and thus allowing the gradual evolution observed experimentally.Résumé -Connectivité de l'espace poreux et propriétés de transport des roches -La connectivité porale est probablement l'un des plus importants facteurs affectant la perméabilité des roches réservoir. En outre, les effets de connectivité ne sont pas limités aux seuls matériaux approchant un seuil de percolation mais peuvent avoir lieu progressivement dans des roches soumises à des processus tels que la diagénèse mécanique ou chimique. Dans cette étude, nous avons compilé plusieurs jeux, préalablement publiés, de mesures de porosité, perméabilité et facteur de formation, obtenues sur des agrégats granulaires non-consolidés, pour lesquels la connectivité ne change pas, ainsi que dans deux autres matériaux, billes de verre frittées et grès de Fontainebleau, pour lesquels elle varie. Nous avons comparé ces données aux prédictions d'un modèle de perméabilité de type Kozeny-Carman, qui ne tient pas compte des variations de connectivité, et à celles du modèle de Bernabé et al. (2010Bernabé et al. ( , 2011

Preferential flow channeling and viscous fingering are widely observed phenomena in heterogeneous porous media from the pore scale to the core and reservoir scales. The transition from capillary to viscous fingering with increasing injection rate is also a well‐known phenomenon. Based on the previously observed visual similarity of viscous fingers and preferential single‐phase flow paths in 2‐D simulations, we postulate that these single‐ and two‐phase flow patterns should also be interrelated in 3‐D porous media. Capillary fingering is a manifestation of invasion percolation, a process restricted to the subnetwork of pores obtained from the critical path analysis. We investigated single‐phase flow channeling by applying a method similar to critical path analysis to the flow rate field and compared the subnetwork thus determined to the set of invaded pipes in drainage simulations. Our aim is to quantify the relation between preferential flow paths and viscous fingering, its dependence on pore‐scale heterogeneity and pore connectivity, and ultimately to upscale the network observations to the field scale appropriate for the engineering applications involving drainage in heterogeneous media.

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