The ﬂuid ﬂow properties of faults are highly variable and spatially heterogeneous. We use numerical simulation of ﬂow through ﬁeld maps of detailed fault zone architecture to demonstrate that ﬂow across the fault zone is controlled by connected high-permeability pathways, which are highly tortuous in mapped fault outcrops. Such small-scale, geometrically complex, fault zone architectural features can never be resolved for subsurface faults. Consequently, the key to prediction of subsurface bulk fault zone hydraulic properties is a statistical characterisation of the likelihood and frequency of such connected pathways. We demonstrate for a single architectural feature, the fault core, that thickness variation along strike can be well described by a spatially correlated random ﬁeld with a spherical covariance structure. These data are from a single site in a speciﬁc lithology. To enable such statistics to be used to make predictions at other sites, a large number of similar datasets must be pooled. This will enable us to relate such spatial statistics to gross properties such as host rock lithology and fault throw, which are measurable for subsurface faults.
|Title of host publication||The Internal Structure of Fault Zones: Implications for Mechanical and Fluid-Flow Properties - Special Publication no. 299|
|Number of pages||6|
|Publication status||Published - 2008|
- cicil engineering
- fluid dynamics