--> Abstract: Fault Displacement Gradients and Associated Deformation on Normal Faults, by Morris, Alan P.; McGinnis, Ronald N.; Ferrill, David A.; #90163 (2013)
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Previous HitFaultNext Hit Displacement Gradients and Associated Deformation on Normal Faults

Morris, Alan P.; McGinnis, Ronald N.; Ferrill, David A.

Faults are important components of hydrocarbon and other reservoirs; they can affect trapping of fluids, flow pathways, compartmentalization, production rates, and through these, production strategies, and economic outcomes. Displacement gradients on faults are associated with off-Previous HitfaultNext Hit deformation, which can be manifest as faulting, extension fracturing, or folding. In this work, displacement gradients - both in the slip direction and laterally - on a well-exposed large-displacement ("seismic-scale") normal Previous HitfaultNext Hit within the Balcones Previous HitFaultNext Hit System of south-central Texas are correlated with "anomalous" deformation patterns adjacent to the Previous HitfaultNext Hit. This anomalous deformation is manifest by two superposed small-displacement Previous HitfaultNext Hit systems, including (i) an earlier set that formed in response to a displacement gradient in the slip direction, and (ii) a later set of oblique faults that formed in a perturbed stress and strain field in response to a lateral displacement gradient on the Previous HitfaultNext Hit. Use of bed-dip, Previous HitfaultNext Hit cutoff relationships, and small-displacement Previous HitfaultNext Hit patterns in the adjacent rock volume to inform strain and paleo-stress estimates indicates that displacement gradients on the seismic-scale Previous HitfaultNext Hit provide a means by which the smaller (subseismic-scale and off-Previous HitfaultNext Hit) deformation features can be predicted both in terms of orientation and intensity. Specifically, lateral displacement gradients on a normal Previous HitfaultNext Hit with dip-slip displacement will generate Previous HitfaultNext Hit-strike-parallel extension, causing anomalously oriented (in the far-field stress context) deformation features adjacent to the Previous HitfaultNext Hit. Displacement gradient analysis can be used to help predict the characteristics of sub-seismic scale deformation within a reservoir adjacent to a seismic-scale normal Previous HitfaultTop.


AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013