A Geo‐Structurally Based Correction Factor for Apparent Dissolution Rates in Fractured Media

Abstract

Hydrology within fractured rocks is complex, with variable Péclet conditions reflecting the relative importance of fluid advection and diffusion on the movement of solutes. In many of these systems, the fluids passing through the fractures will be out of equilibrium with the resident minerals, and, in turn, a variety of reactions, for example, dissolution and precipitation, take place (Deng & Spycher, 2019). These geochemical processes can lead to the evolution of the fracture network by changing fracture permeability (Ellis et al., 2013) and potentially driving or inhibiting fracture propagation (Shovkun & Espinoza, 2019). Because the majority of flow in fractured media passes through a small volume relative to the domain size and the reactions are therein localized, these changes can produce a

Quartz Dissolution Effects on Flow Channelization and Transport Behavior in Three‐Dimensional Fracture Networks

“…Thus, as the system evolves with time, the primary and secondary networks become increasingly disparate in terms of hydraulic resistance and geochemical weathering/reactions. These results are in agreement with previous studies and also provide insight into previous studies from the literature where once readily accessible reactive minerals are depleted, the apparent mineral dissolution rate decreases to values that can be orders of magnitude lower than the laboratory-measured rate (Andrews & Navarre-Sitchler, 2021;Atchley et al, 2013;Beisman et al, 2015;Hyman et al, 2022;Jung & Navarre-Sitchler, 2018). In addition to the non-uniformity within each network, the results also clearly show that the magnitude of increased flow channelization is non-uniform between statistically identical networks.…”

“…Thus, the study presented here is an extension of Hyman et al. (2022) by providing a more detailed investigation of how dissolution influences flow channelization in fractured media.…”

“…As previously mentioned, the presence of flow channels indicates the existence of primary sub-networks, also referred to as backbones, within the fracture network. We follow Hyman et al (2022) and adopt a network partitioning definition that is based solely on the network structure, specifically the topology/connectivity, and does not utilize any hydraulic, geometric, or flow information. We identify the disjoint primary and secondary sub-networks by defining the secondary network to be comprised of all dead-end structures, that is, dead-end fractures and cycles, while the primary sub-network is its complement.…”

“…Nonetheless, recent developments in high-performance computing and discrete fracture network (DFN) models make such simulations possible. In one recent study, Hyman et al (2022) performed a series of high-fidelity reactive transport simulations of mineral dissolution in 3D DFNs to identify a link between flow channelization and reactive transport observations. They developed a correction factor to linear transition state theory to estimate the apparent dissolution rate of the network, which is known to deviate from laboratory measurements by multiple orders of magnitude (Arvidson & Luttge, 2010;Beckingham et al, 2017;Lüttge et al, 2013;Maher, 2010;Maher et al, 2009;Qin & Beckingham, 2021;White & Brantley, 2003;Zhu & Lu, 2009).…”

Surface‐Volume Scaling Controlled by Dissolution Regimes in a Multiphase Flow Environment

“…However, in regime II, C f cannot reach a stable plateau, and the error of reaction rate predicted by the model (Equation 1) amplifies as the dissolution processes because the dissolution rate is suppressed by the barrier effect (Figure 1g and Figure S8b in Supporting Information S1). Although this shifting method using the correction factor C f is practiced in some previous studies (Beckingham et al, 2016;Hyman et al, 2022), our work quantifies its predictability controlled by dissolution regimes in a multiphase flow environment for the first time.…”