About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract

AAPG Bulletin, V. 98, No. 6 (June 2014), P. 11611184.

Copyright copy2014. The American Association of Petroleum Geologists. All rights reserved.

DOI: 10.1306/10311312204

Fault displacement gradients on normal faults and associated deformation

Alan P. Morris,1 Ronald N. McGinnis,2 and David A. Ferrill3

1Department of Earth, Material, and Planetary Sciences, Southwest Research Institute®, San Antonio, Texas 78238; [email protected]
2Department of Earth, Material, and Planetary Sciences, Southwest Research Institute®, San Antonio, Texas 78238; [email protected]
3Department of Earth, Material, and Planetary Sciences, Southwest Research Institute®, San Antonio, Texas 78238; [email protected]

ABSTRACT

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-fault 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 fault within the Balcones fault system of south-central Texas are correlated with anomalous deformation patterns adjacent to the fault. This anomalous deformation consists of two superimposed small-displacement fault systems, including (1) an earlier set that formed in response to a displacement gradient in the slip direction, and (2) a later set of oblique faults that formed in a perturbed stress-and-strain field in response to a lateral displacement gradient on the fault. Bed dip, fault-cutoff relationships, and small-displacement fault patterns in the adjacent rock volume inform strain and paleostress estimates. Results indicate that seismically resolvable displacement gradients on and bed dips adjacent to the seismic-scale fault provide a means by which the smaller (subseismic-scale and off-fault) deformation features can be predicted both in terms of orientation and intensity. Specifically, lateral displacement gradients on a normal fault with dip-slip displacement will generate fault-strike-parallel extension, causing anomalously oriented (in the far-field stress context) deformation features adjacent to the fault. Displacement gradient analysis can be used to help predict the characteristics of subseismic-scale deformation within a reservoir adjacent to a seismic-scale normal fault.

Pay-Per-View Purchase Options

The article is available through a document delivery service. Explain these Purchase Options.

Protected Document: $10
Internal PDF Document: $14
Open PDF Document: $24

AAPG Member?

Please login with your Member username and password.

Members of AAPG receive access to the full AAPG Bulletin Archives as part of their membership. For more information, contact the AAPG Membership Department at [email protected].