Outcrop Analogues of Fault
Systems Showing Variations in Linkage, Segmentation and Compartmentalisation with Increasing Deformation
The progressive development of a fault
zone, in response to ongoing deformation, can give rise to major changes in the potential of the
fault
to impede or enhance hydrocarbon flow. We show a number of detailed 3D outcrop models of extensional
fault
systems (captured using terrestrial Lidar) that illustrate typical effects of increasing deformation on
fault
linkage, segmentation and reservoir compartmentalisation. Examples of low-strain extensional
fault
systems are often characterised by sparsely distributed, isolated faults and low levels of
fault
linkage. There is little compartmentalisation, and the likely effects on fluid flow are minor. As deformation accumulates, ongoing
fault
growth causes increased
fault
interaction and linkage; i.e. there is a tendency for strain to localise onto a fewer number of larger structures. Mature
fault
zones that have accommodated large extension are often highly linked. We show an example of a large regional-scale active
fault
zone, and present evidence to suggest that the host volume is compartmentalised on at least three scales of observation (~10km, ~100m, ~10m). This appears to occur by progressive linkage of
fault
panels of different orientations (giving rise to curved composite
fault
surfaces), and by bifurcation of
fault
panels (so that different parts of a single panel are linked with other panels of different orientations). These processes give rise to complex patterns of 3D
fault
linkage, and can generate a large amount of low permeability cataclastic
fault
product that will significantly impede hydrocarbon flow.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009