Faulting, fault sealing and fluid flow in hydrocarbon reservoirs: an introduction

Knipe, R. J.; Jones, G.; Fisher, Q.J.

doi:10.1144/gsl.sp.1998.147.01.01

Cited by 142 publications

(77 citation statements)

References 27 publications

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“…Natural fault zones exhibit complex internal architectures composed of clusters and networks of small faults and fractures surrounding larger slip surfaces (Engelder 1974;Knipe et al 1998). The behaviour of fluids and strength characteristics in these zones depend upon the distribution, evolution and connectivity of the fault rocks with different properties in the network (Caine & Foster 1999;Haneberg et al, 1999).…”

Section: Fluids Faults and Detachmentsmentioning

confidence: 99%

The nature and tectonic significance of fault-zone weakening: an introduction

Rutter

Holdsworth

Knipe

2001

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Fault zones control the location, architecture and evolution of a broad range of geological features, act as conduits for the focused migration of economically important fluids and, as most seismicity is associated with active faults, they also constitute one of the most important global geological hazards. In general, the repeated localization of displacements along faults and shear zones, often over very long time scales, strongly suggests that they are weak relative to their surrounding wall rocks. Geophysical observations from plate boundary faults such as the San Andreas fault additionally suggest that this fault zone is weak in an absolute sense, although this remains a controversial issue. Our understanding of fault-zone structure and mechanical behaviour derive from three main sources of information: (1) studies of natural fault zones and their deformation products (fault rocks); (2) seismological and neotectonic studies of currently active natural fault systems; (3) laboratory-based deformation experiments using rocks or rock-analogue materials. These provide us with a basic understanding of brittle faulting in the upper crust of the Earth where the stress state is limited by the frictional strength of networks of faults under the prevailing fluid-pressure conditions. Under the long-term loading conditions typical of geological fault zones, poorly understood phenomena such as subcritical crack growth in fracture process zones are likely to be of major importance in controlling both fault growth and strength. Grain-size reduction in highly strained fault rocks produced in the plastic-viscous and deeper parts of frictional regime can lead to changes in deformation mechanisms and relative weakening that can account for the localization of deformation and repeated reactivation of crustal faults. Our understanding the interactions between deformation mechanisms, metamorphic processes and the flow of chemically active fluids is a key area for future study. An improved understanding of how fault-or shear-zone linkages, strength and microstructure evolve over large changes in finite strain will ultimately lead to the development of geologically more realistic numerical models of lithosphere deformation that incorporate displacements concentrated into narrow, weaker fault zones.In continental and oceanic regions, the deformation of the Earth's crust (and lithosphere) is characteristically heterogeneous, with most displacements being localized into linked systems of faults and shear zones. In both intraplate and plate margin settings, these approximately planar or tabular deformation zones influence strongly the location, architecture and evolution of a broad range of geological features, including rift basins, orogenic belts and transcurrent fault systems. Many fault zones are known to act as conduits for the focused migration of fluids and clearly play a central role in determining the location, modes of transport and emplacement of economically important hydrocarbon reservoirs, hydrothermal mineral d...

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Section: Fluids Faults and Detachmentsmentioning

confidence: 99%

The nature and tectonic significance of fault-zone weakening: an introduction

Rutter

Holdsworth

Knipe

2001

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“…The variability of brittle fault zones permeability has been widely discussed these last twenty years [27]. Depending on the stratigraphic column and displacements scale [28], faults juxtapose compartments which may be sealant or highly permeable [29]. Fault zones may involve one or several core zones, composed of fault rocks, surrounded by a damage zone corresponding to highly fractured host rocks.…”

Section: Introductionmentioning

confidence: 99%

Fault-Related Controls on Upward Hydrothermal Flow: An Integrated Geological Study of the Têt Fault System, Eastern Pyrénées (France)

et al. 2017

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The way faults control upward fluid flow in nonmagmatic hydrothermal systems in extensional context is still unclear. In the Eastern Pyrénées, an alignment of twenty-nine hot springs (29 ∘ C to 73 ∘ C), along the normal Têt fault, offers the opportunity to study this process. Using an integrated multiscale geological approach including mapping, remote sensing, and macro-and microscopic analyses of fault zones, we show that emergence is always located in crystalline rocks at gneiss-metasediments contacts, mostly in the Têt fault footwall. The hot springs distribution is related to high topographic reliefs, which are associated with fault throw and segmentation. In more detail, emergence localizes either (1) in brittle fault damage zones at the intersection between the Têt fault and subsidiary faults or (2) in ductile faults where dissolution cavities are observed along foliations, allowing juxtaposition of metasediments. Using these observations and 2D simple numerical simulation, we propose a hydrogeological model of upward hydrothermal flow. Meteoric fluids, infiltrated at high elevation in the fault footwall relief, get warmer at depth because of the geothermal gradient. Topography-related hydraulic gradient and buoyancy forces cause hot fluid rise along permeability anisotropies associated with lithological juxtapositions, fracture, and fault zone compositions.

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“…Earthquakes nucleate in rocks at depth (e.g., FAGERENG and TOY 2011;SIBSON 1977;2003), yet until recently (see ANDO, 2001;BOULLIER et al 2009;CORNET et al 2004;HEERMANCE et al 2003;HICKMAN et al 2004;HICKMAN et al 2007;HIRONO et al 2007;OHTANI et al 2000;TANAKA et al 2002;TOBIN and KINOSHITA 2006;TOWNEND et al 2009;ZO-BACK et al 2007;ZOBACK et al 2010), we have only had limited sampling of rocks or observations from within active plate-boundary fault zones where earthquake nucleation and rupture propagation has occurred. Direct knowledge of rock properties from active fault zones through integrated drilling, field, and laboratory studies can provide significant insight into fault processes, and can be used to: (1) identify systematic compositional and textural changes to infer the chemical and physical processes involved in fault zone evolution; (2) delineate the dimensions of the structural and permeability fault zone architecture; and (3) consider the role of fluid migration and fluidrelated alteration throughout deformation (BRODSKY et al 2010;CAINE et al 1996CAINE et al , 2010CHESTER and LOGAN 1986;COWAN 1999;EVANS and CHESTER 1995;FAGERENG and SIBSON 2010;KNIPE et al 1998;MARONE and RICHARDSON 2010;MENEGHINI and MOORE 2007;ROWE et al 2009;SHIPTON AND COWIE and COWIE 2001;SIBSON 1989;WIBBERLEY et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Composition, Alteration, and Texture of Fault-Related Rocks from Safod Core and Surface Outcrop Analogs: Evidence for Deformation Processes and Fluid-Rock Interactions

Bradbury

Davis

Shervais

et al. 2014

Pure Appl. Geophys.

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Abstract-We examine the fine-scale variations in mineralogical composition, geochemical alteration, and texture of the faultrelated rocks from the Phase 3 whole-rock core sampled between 3,187.4 and 3,301.4 m measured depth within the San Andreas Fault Observatory at Depth (SAFOD) borehole near Parkfield, California. This work provides insight into the physical and chemical properties, structural architecture, and fluid-rock interactions associated with the actively deforming traces of the San Andreas Fault zone at depth. Exhumed outcrops within the SAF system comprised of serpentinitebearing protolith are examined for comparison at San Simeon, Goat Rock State Park, and Nelson Creek, California. In the Phase 3 SAFOD drillcore samples, the fault-related rocks consist of multiple juxtaposed lenses of sheared, foliated siltstone and shale with blockin-matrix fabric, black cataclasite to ultracataclasite, and sheared serpentinite-bearing, finely foliated fault gouge. Meters-wide zones of sheared rock and fault gouge correlate to the sites of active borehole casing deformation and are characterized by scaly clay fabric with multiple discrete slip surfaces or anastomosing shear zones that surround conglobulated or rounded clasts of compacted clay and/or serpentinite. The fine gouge matrix is composed of Mgrich clays and serpentine minerals (saponite ± palygorskite, and lizardite ± chrysotile). Whole-rock geochemistry data show increases in Fe-, Mg-, Ni-, and Cr-oxides and hydroxides, Fe-sulfides, and C-rich material, with a total organic content of [1 % locally in the fault-related rocks. The faults sampled in the field are composed of meters-thick zones of cohesive to non-cohesive, serpentinite-bearing foliated clay gouge and black fine-grained fault rock derived from sheared Franciscan Formation or serpentinized Coast Range Ophiolite. X-ray diffraction of outcrop samples shows that the foliated clay gouge is composed primarily of saponite and serpentinite, with localized increases in Ni-and Cr-oxides and C-rich material over several meters. Mesoscopic and microscopic textures and deformation mechanisms interpreted from the outcrop sites are remarkably similar to those observed in the SAFOD core. Microscale to meso-scale fabrics observed in the SAFOD core exhibit textural characteristics that are common in deformed serpentinites and are often attributed to aseismic deformation with episodic seismic slip. The mineralogy and whole-rock geochemistry results indicate that the fault zone experienced transient fluid-rock interactions with fluids of varying chemical composition, including evidence for highly reducing, hydrocarbon-bearing fluids.

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Faulting, fault sealing and fluid flow in hydrocarbon reservoirs: an introduction

Cited by 142 publications

References 27 publications

The nature and tectonic significance of fault-zone weakening: an introduction

The nature and tectonic significance of fault-zone weakening: an introduction

Fault-Related Controls on Upward Hydrothermal Flow: An Integrated Geological Study of the Têt Fault System, Eastern Pyrénées (France)

Composition, Alteration, and Texture of Fault-Related Rocks from Safod Core and Surface Outcrop Analogs: Evidence for Deformation Processes and Fluid-Rock Interactions

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