Pore-Scale Imaging and Modelling of Reactive Flow in Evolving Porous Media: Tracking the Dynamics of the Fluid–Rock Interface

Abstract

Fluid-mineral and fluid-rock interfaces are key parameters controlling the reactivity and fate of fluids in reservoir rocks and aquifers. The interface dynamics through space and time results from complex processes involving a tight coupling between chemical reactions and transport of species as well as a strong dependence on the physical, chemical, mineralogical and structural properties of the reacting solid phases. In this article, we review the recent advances in pore-scale imaging and reactive flow modelling applied to interface dynamics. Digital rocks derived from time-lapse X-ray micro-tomography imaging gives unprecedented opportunity to track the interface evolution during reactive flow experiments in porous or fractured media, and evaluate locally mineral reactivity. The recent improvements in porescale reactive transport modelling allow for a fine description of flow and transport that integrates moving fluid-mineral interfaces inherent to chemical reactions. Combined with three-dimensional digital images, pore-scale reactive transport modelling complements and augments laboratory experiments. The most advanced multi-scale models integrate sub-voxel porosity and processes which relate to imaging instrument resolution and improve upscaling possibilities. Two example applications based on the solver porousMedia4Foam illustrate the dynamics of the interface for different transport regimes (i.e., diffusive-to advective-dominant) and rock matrix properties (i.e., permeable versus impermeable, and homogeneous versus polymineralic). These parameters affect both the interface roughness and its geometry evolution, from sharp front to smeared (i.e., diffuse) interface. The paper concludes by discussing the challenges associated with precipitation processes in porous media, rock texture and composition (i.e., physical and mineralogical heterogeneity), and upscaling to larger scales.

Pore-Scale Modeling of Mineral Growth and Nucleation in Reactive Flow

“…Precise control of interface dynamics has substantial implications in geological and environmental systems as it is described in recent comprehensive review by Noiriel and Soulaine (2021). The review is focused on recent advances in X-ray computed tomography (Noiriel and Daval, 2017;Yuan et al, 2021) and development of pore-scale reactive transport models (Molins et al, 2012;Prasianakis et al, 2020;Soulaine et al, 2021;Yang et al, 2021).…”

Four-dimensional X-ray micro-tomography imaging of dynamic processes in geosciences

“…After segmentation and labelling of the different phases, identification and tracking of the interface motion becomes possible. The different methods to extract and represent the interface displacement from XMT volumes as their limitations are described in Noiriel and Soulaine [2021]. Under flow or reactive conditions, fluid-fluid or fluid-mineral interface shift can be directly linked to the rate of fluid displacement or the amount of solid removed or precipitated by reactive fluids.…”

“…If evaluation of the motion of sharp, relatively flat interfaces from 3D data sets does not pose a serious problem, it is far more complicated to deal with curved or smeared (i.e. diffuse) interfaces [ Noiriel and Soulaine, 2021]. Evaluation of the displacement between two time steps lies in the calculation of the distance between two surfaces, i.e., the interface at times t i and t i +1 (Figure 3a).…”

The Impact of Sub-Resolution Porosity on Numerical Simulations of Multiphase Flow

“…This approach relies on locally-averaged Navier-Stokes equations that asymptotically approach Darcy's law in regions with SRP and the Navier-Stokes equations in fully resolved pores. This model has proven fairly flexible and has been used to evaluate the effects of static (Knackstedt et al, 2006;Apourvari and Arns, 2014;Scheibe et al, 2015;Guo et al, 2018;Kang et al, 2019;Singh, 2019), reactive (Soulaine et al, 2017;Noiriel and Soulaine, 2021), and deformable (Carrillo and Bourg, 2019) SRP on the permeability of heterogeneous porous media. Furthermore, through careful consideration of capillary and viscous effects within the SRP (i.e., fluid mobility, relative permeabilities, and capillary pressures), recent investigations have successfully expanded and validated the Micro-Continuum Approach for situations involving the flow of multiple fluids in multiscale porous media (Soulaine et al, 2018;Carrillo et al, 2020;Carrillo and Bourg, 2021b,a).…”