The mechanics of clay smearing along faults

Abstract

A clay-or shale-rich fault gouge can signifi cantly reduce fault permeability. Therefore, predictions of the volume of clay or shale that may be smeared along a fault trace are important for estimating the fl uid connectivity of groundwater and hydrocarbon reservoir systems. Here, we show how fault smears develop spontaneously in layered soil systems with varying friction coeffi cients, and we present a quantitative dynamic model for such behavior. The model is based on Mohr-Coulomb failure theory, and using discrete element computations, we demonstrate how the model framework can predict the fault smear potential from soil friction angles and layer thicknesses.

Geologic carbon storage is unlikely to trigger large earthquakes and reactivate faults through which CO2could leak

“…We contend that close analysis of fault zone architecture reveals that CO 2 will not easily penetrate into the portions of the fault contained within shale rocks (31). Fault permeability, which is highly variable in reservoir-caprock sequences (32,33), decreases several orders of magnitude for increasing clay content, leading to a much lower permeability in the caprocks than in the reservoirs (34,35). Rocks with low clay content, like reservoirs, tend to fracture, increasing the width of the damaged zone and usually increasing permeability in response to shear (34).…”

Seismic Imaging of Salt-influenced Compressional Folds

“…For these reasons, this method has been used in many geological problems, especially involving the analysis of highstrain brittle deformation in the sedimentary cover such as normal faulting in layered sequences (Schöpfer et al, 2006(Schöpfer et al, , 2007a(Schöpfer et al, , 2007bEgholm et al, 2008;, fault bend folding (Strayer et al, 2004;Benesh et al, 2007), fault-propagation folding (Finch et al, 2003(Finch et al, , 2004Cardozo et al, 2005;Hardy andFinch 2006, 2007) (Hardy and Finch, 2005), and doubly vergent thrust wedges (Hardy et al, 2009), to name some examples. In all these cases, the results have a strong correspondence to the deformation seen in the field and seismic.…”

Effect of Surface Morphology on the Dissipation During Shear and Slip Along a Rock–Rock Interface that Contains a Visco-elastic Core

“…At the outcrop scale, it is also common to observe, in faulted sedimentary basins, that clay layers smear a fault interface (EGHOLM and CLAUSEN, 2008) and lubricate it (see Fig. 1d).…”