Upscaling Strategies of Porosity-Permeability Correlations in Reacting Environments from Pore-Scale Simulations

Abstract

In geochemically reacting environments, the mineral dissolution and precipitation alters the structural and transport properties of the media of interest. The chemical and structural heterogeneities of the porous media affect the temporal evolution of the permeability with respect to porosity. Such correlations follow a nonlinear trend, which is difficult to estimate a priori and without knowledge of the microstructure itself, especially under the presence of strong chemical gradients. Macroscopic fieldscale codes require such an input, and in the absence of exact descriptions, simplified correlations are used. After highlighting the diversity of microstructural evolution paths, due to dissolution, we discuss possible upscaling strategies.

A Novel Modeling Approach to Stochastically Evaluate the Impact of Pore Network Geometry, Chemistry and Topology on Fluid Transport

“…Improvements in the network's porosity are also expected to be beneficial, but only after the 'critical' threshold of ~ 30% porosity is reached. This is consistent with results reported by Prasianakis et al (2018). The size distribution of the pore throats is an important feature, but, in the case of unconventional reservoirs, it depends on factors that operators have no control over.…”

“…Since our 3D lattices are periodic in all 3 dimensions, we do not expect the 35% threshold to be strongly dependent on the representative elementary volume (REV) used to construct our systems. In fact, a similar threshold porosity value (~ 39%) was observed by Prasianakis et al (2018), who simulated an acidic aqueous mixture diffusing through a calcite mineral matrix, dissolving part of it, thus increasing the system's porosity. An exponential increase in permeability was observed when the 39% porosity threshold was reached.…”

“…In agreement with those observations, our results suggest that the network's transport behavior can be significantly improved when the porosity is artificially altered. However, the process of modifying the network's porosity utilizing chemical reactions should be carefully planned, as the reaction by-products (mineral precipitation in the case study by Prasianakis et al 2018) could clog the existing pore bodies, thereby reducing network connectivity, and thus fluid transport.…”

Simulation of mineral dissolution at the pore scale with evolving fluid-solid interfaces: review of approaches and benchmark problem set

“…Due to their simplicity, they can be programmed in many different computer languages and can be executed entirely, for example, on general purpose graphical units (GP-GPU's). A family of such codes has been developed at Paul Scherrer Institut over the past few years with applications that range from catalytic reactive flows [43], to micro-flows [81], to threedimensional porous media and multiphase flows [83,87], and to geochemical flows [85]. The lattice Boltzmann solver used here follows the passive scalar approach [84].…”

Towards Digital Twins: Machine Learning Based Process Coupling and Multiscale Modelling of Reactive Transport Phenomena

“…the pore scale [1], the models and the experimental research tools are well established, an automated coupling between processes at different scales remains very challenging [2]. For example, the geochemical evolution of the rock microstructure can result in different permeability-porosity pathways depending on several parameters relevant to the chemical and flow conditions [3]. Parametric microscopic simulation results have to be subsequently up-scaled to be used by field-scale simulators.…”