Abstract
Fault-zones significantly influence the migration of fluids in the
subsurface and can be important controls on the local as well as
regional hydrogeology. Hence, understanding the evolution of fault
porosity-permeability is critical for many engineering applications
(like geologic carbon sequestration, enhanced geothermal systems,
groundwater remediation, etc.) as well as geological studies (like
sediment diagenesis, seismic activities, hydrothermal ore deposition,
etc.). The highly heterogeneous pore structure of fault-zones along with
the wide range of hydrogeochemical heterogeneity that a fault-zone can
cut through make conduit fault-zones a dynamic reactive transport
environment that can be highly complex to accurately model. In this
paper, we present a critical review of the possible ways of modeling
reactive fluid flow through fault-zones, particularly from the
perspective of chemically driven “self-sealing” or “self-enhancing”
of fault-zones. Along with an in-depth review of the literature, we
consider key issues related to different conceptual models (e.g.
fault-zone as a network of fractures or as a combination of damaged zone
and fault core), modeling approaches (e.g. multiple continua, discrete
fracture networks, pore-scale models) and kinetics of water-rock
interactions. Inherent modeling aspects related to dimensionality (e.g.
1D vs 2D) and the dimensionless Damköhler number are explored. Moreover,
we use a case-study of the Little Grand Wash Fault-zone from central
Utah as an example in the review. Finally, critical aspects of reactive
transport modeling 2 like multiscale approaches and chemo-mechanical
coupling are also addressed in the context of fault-zones.