Overprinting faulting mechanisms in high porosity sandstones of SE Utah

Davatzes, Nicholas C.; Aydin, Atilla

doi:10.1016/s0191-8141(03)00043-9

Cited by 111 publications

(40 citation statements)

References 51 publications

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“…The current study undertakes an examination of a relay ramp in mature, aeolian sandstones having undergone faulting at c. 2 km depth Davatzes & Aydin 2003). In other areas, such as the Jurassic Brent reservoirs in the North Sea, faulting has occurred at near-surface depths.…”

Section: Applicabilitymentioning

confidence: 99%

“…The Delicate Arch Ramp per se was mapped, but was not a main subject of their studies. Other studies in the area include microstructural studies of deformation bands , studies of local and regional fracture patterns (Cruikshank & Aydin 1995;Kattenhorn et al 2000;Davatzes & Aydin 2003) and a numerical study of pressure drawdown in faulted sandstone reservoirs (Matthäi et al 1998).…”

Section: Geological Frameworkmentioning

confidence: 99%

“…Relay ramps may, therefore, exercise significant controls on fluid flow across faults in producing hydrocarbon reservoirs. However, some studies have documented that overlapping faults commonly are associated with the formation of a complex and anomalously wide fault damage zone (linking damage zone of Kim et al 2004), which may well envelope the entire relay zone (Davatzes & Aydin 2003;Kim et al 2004;Fossen et al 2005;Ciftci & Bozkurt 2006;Rotevatn et al 2007). Sub-seismic structural damage in the relay ramp may have profound effects on fluid conductivity along the ramp (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Dynamic investigation of the effect of a relay ramp on simulated fluid flow: geocellular modelling of the Delicate Arch Ramp, Utah

Rotevatn

Tveranger

Howell

et al. 2009

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A fluid flow simulation study was performed to investigate potential contrasts in reservoir performance between models displaying a soft-linked relay ramp vs. models with a continuous fault. The relay ramp model is based on a well-exposed outcrop analogue -the Delicate Arch Ramp, Arches National Park, Utah. In outcrop, the relay ramp exhibits a pervasive system of cataclastic deformation bands, which were mapped and incorporated into the reservoir simulation models. Several models were simulated, using deformation-band permeability as the main variable tested. Results show that when compared to flow across continuous faults, the presence of soft-linked relay ramps enhances net flow across the fault zone in all tested scenarios. Comparing models with deformation bands to the model that includes the ramp but no deformation bands illustrates that, although having an impact on flow tortuosity and sweep efficiency, deformation bands must have a very low permeability and be numerous before having a negative impact on recovery. Deformation bands with midrange permeabilities were shown to have a positive effect on recovery in the relay models, as they increase flow tortuosity and enhance sweep, causing later water breakthrough and prolonging production. Using very low-permeable deformation bands in the same models caused extremely poor pressure communication between the fault-breached compartments, despite the geometric connectivity provided by the sub-continuous relay beds.

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Section: Applicabilitymentioning

confidence: 99%

Section: Geological Frameworkmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dynamic investigation of the effect of a relay ramp on simulated fluid flow: geocellular modelling of the Delicate Arch Ramp, Utah

Rotevatn

Tveranger

Howell

et al. 2009

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“…In some cases, this heterogeneity can be inherited and may be related either to rock lithology or preexisting structural elements (e.g., BERGBAUER and MARTEL, 1999;DAVATZES and AYDIN, 2003;MYERS and AYDIN, 2004;POLLARD, 1983a, 1983b). Also, heterogeneity is commonly related to the processes responsible for fault growth, slip, and evolution: Rocks adjacent to faults are typically fractured due to brittle deformation associated with repeated slip events on the main fault surface(s).…”

Section: Introductionmentioning

confidence: 99%

Influence of Outcrop Scale Fractures on the Effective Stiffness of Fault Damage Zone Rocks

Griffith

Sanz

Pollard

2009

Pure appl. geophys.

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We combine detailed mapping and microstructural analyses of small fault zones in granodiorite with numerical mechanical models to estimate the effect of mesoscopic (outcrop-scale) damage zone fractures on the effective stiffness of the fault zone rocks. The Bear Creek fault zones were active at depths between 4 and 15 km and localize mesoscopic off-fault damage into tabular zones between two subparallel boundary faults, producing a fracture-induced material contrast across the boundary faults with softer rocks between the boundary faults and intact granodiorite outside the boundary faults. Using digitized fault zone fracture maps as the modeled fault geometries, we conduct nonlinear uniaxial compression tests using a novel finite-element method code as the experimental ''laboratory'' apparatus. Map measurements show that the fault zones have high nondimensional facture densities (>1), and damage zone fractures anastamose and intersect, making existing analytical effective medium models inadequate for estimation of the effective elastic properties. Numerical experiments show that the damage zone is strongly anisotropic and the bulk response of the fault zone is strain-weakening. Normal strains as small as 2% can induce a reduction of the overall stiffness of up to 75%. Fracture-induced effective stiffness changes are large enough to locally be greater than intact modulus changes across the fault due to juxtaposition of rocks of different lithologies; therefore mesoscopic fracturing is as important as rock type when considering material or bimaterial effects on earthquake mechanics. These results have important implications for earthquake rupture mechanics models, because mesoscopic damage zone fractures can cause a material contrast across the faults as large as any lithology-based material contrast at seismogenic depths, and the effective moduli can be highly variable during a single rupture event.

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“…, sandstones (Davatzes and Aydin, 2003;Peters, 2009), and conglomerates (Bossiere et al, 1996). For example, honeycomb weathering forms N0.5 m are defined as Tafoni, whereas b0.5 m are defined as Alveoles (Evelpidou, et al, 2010).…”

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confidence: 99%