Role of Pore and Pore‐Throat Distributions in Controlling Permeability in Heterogeneous Mineral Dissolution and Precipitation Scenarios

Abstract

Mineral dissolution and precipitation reactions can significantly alter the porosity and permeability of porous media. While porosity generally increases with dissolution and decreases with precipitation, permeability is controlled by the spatial locations of reactions in discrete pores and pore throats and in the greater pore network. Geochemical reactions have been observed to occur both uniformly and nonuniformly in porous media, driven by parameters such as mineral distribution, grain size, and Peclet and Damkohler numbers. Pore network modeling can be used to simulate the impact of pore‐scale alterations on permeability, requiring only pore and pore‐throat size distributions and pore connectivity. Here, the impact of variations in pore and pore‐throat size distributions on reactive permeability for uniform and nonuniform spatial distributions of reactions is evaluated. A series of pore network models are created and populated with pore and pore‐throat size distributions of varying types (skewed, normal, and uniform) to represent differences in network topology and characterization methods. The impacts of these distributions on reactive permeability are then simulated for uniform and nonuniform reaction conditions by increasing or decreasing pore and pore‐throat sizes in a prescribed manner to reflect dissolution and precipitation, respectively. Overall, simulations reveal that porosity‐permeability evolution varies with reaction scenario and is qualitatively consistent for the different pore and pore‐throat size distributions. Common macroscopic porosity‐permeability relationships work well for some reaction scenarios but are unable to reflect size‐dependent reactions. A new modified version of the Verma‐Pruess relationship is created and able to successfully reflect the porosity‐permeability evolution for size‐dependent reactions.

Combination of MRI and SEM to Assess Changes in the Chemical Properties and Permeability of Porous Media due to Barite Precipitation

“…In parallel the effective transverse relaxation rates increased by a factor of three. This, at first glance, unexpected behavior might reflect a decrease in pore and pore-throat sizes as shown in the numerical investigations of Steinwinder and Beckingham [21]. In addition, the presence of localized clogging zones (Figure 3) could strongly affect the tortuosity of the system, decreasing also its permeability which is in in agreement with previous observations [16].…”

“…The Kozeny-Carman equation predicts fairly well the hydraulic conductivity of most soils with some exceptions involving heterogeneity or unconnected porosities (e.g., [18,19]). This is because the empirical relationship does not account for the changes in the microstructure and the pore architecture of the porous medium, such as pore throat distributions and connectivity of the pore network [20,21]. In fact, the Kozeny-Carman equation was not originally developed to describe the permeability changes of porous media undergoing alteration in its pore architecture [22].…”

The quality of geothermal reservoir of the Lower Jurassic aquifer in the Mogilno-Łódź Trough (Polish Lowlands)

“…Rock composition has a significant effect on the reservoir parameters such as porosity and permeability. High porosity and permeability play a significant role in fluid migration [4,6]. Sandsotnes from boreholes located in the Mogilno-Łódź Trough represents mainly by quartz arenites and wackes which have variation in porosity and permeability (min.…”

“…Mineral dissolution and precipitation reactions in porous media can result in changes in porosity and permeability [4,5]. Moreover, the lithology of reservoir rocks, as well as the water-rock thermodynamic equilibrium, affect the chemical composition of groundwater and its exploitation [6].…”

Digital rock physics approach to simulate hydraulic effects of anhydrite cement in Bentheim sandstone

“…Precipitation reduces porosity in general, but its effect on transport properties strongly depends on its location. Various studies discuss if precipitation preferably occurs in larger pores or in contrast in smaller ones (Stack, 2015;Steinwinder and Beckingham, 2019). For the Allermöhe sandstone, it is presumed that larger pores were favoured for anhydrite precipitation during its diagenesis (Pape et al, 2005).…”