Examining the influence of mechanical stratigraphy and displacement profiles on fault linkage and damage zone architecture: an analog study of the Iron Wash Fault, Utah

David Richey
Utah State University, Department of Geology Logan, Utah, USA
[email protected]

Geologic sequestration of anthropogenic carbon dioxide (CO2) in deep, underground geologic formations, including depleted oil and gas reservoirs or stacked saline aquifers, depends on the ability to adequately store injected CO2 with minimal leakage through natural pathways such as faults and facture networks. The Iron Wash Fault (IWF), a NW-SE striking, steeply dipping normal fault with <100m of displacement in the San Rafael Desert of Utah cuts a range of Mesozoic strata and is an analog for sub-surface faults of similar scale within potential CO2 storage sites and hydrocarbon reservoirs. Potential leakage pathways resulting from fault related structures, at both seismic and sub-seismic scales, include fractures, relay zones, synthetic and antithetic faults, fault blocks, fault splays, fault related folds, fault gouge and smear. The IWF is characterized using field observations and active source seismic refraction/ reflection imaging to correlate expressions of fault architecture in outcrop and in the subsurface to understanding the interaction of fault linkage and propagation and their dependence on mechanical stratigraphy. Along-strike heterogeneities such as fault growth structures, expressions of the fault core and fault relay zones at various stages of linkage are characterized with respect to displacement gradients and stratigraphic juxtaposition. Fault geometry at depth and various expressions of fault damage zone related to mechanical stratigraphy provide the basis for the development of theoretical models of fault zone properties, including: scale, architecture, connectivity, interaction with lithology, and predictive models of seal effectiveness for fluids in the subsurface.

AAPG Search and Discovery Article #90157©2012 AAPG Foundation 2012 Grants-in-Aid Projects