How permeable are clays and shales?

Neuzil, Christopher E.

doi:10.1029/93wr02930

Cited by 561 publications

(452 citation statements)

References 31 publications

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“…This analysis identifies permeability structures resulting in steady state pore pressures that are consistent with mechanically and observationally based constraints. The agreement found by Neuzil [1994] between laboratory measurements and bulk permeability estimated from inverse modeling justifies this approach.…”

Section: Model Equationsmentioning

confidence: 48%

“…Results of a rigorous sensitivity analysis suggest that the relationship between bulk permeability and porosity for the Nankai complex falls within the range given by Neuzil [1994] for argillaceous rocks. Furthermore, the relationship between permeability and porosity established through inverse modeling varies little, even with substantial changes in d6collement permeability and underthrust consolidation rate.…”

Section: Discussionmentioning

confidence: 99%

“…• All permeability-porosity functions which yield reasonable steady state pore pressure distributions in the Nankai accretionary complex fall within the range for argillaceous rocks defined by Neuzil [1994]. However, they differ from direct measurements of permeability in sediments of the Nankai complex [e.g., Taylor and Fisher, 1993] (Figure 6).…”

Section: Sensitivity Analysis Of Permeabilities and Steady State Presmentioning

confidence: 99%

“…The thickness of ash layers, which form the bulk of the smectite available for dehydration, is highly variable and depends upon both proximity to the ash source [Taira and Ashi, 1993] design was determined by decreasing horizontal grid spacing until pore pressures and chloride concentrations did not change [McCaffrey, 1994]. We assume that the permeabili• of both accreted and underthrust sediments varies log linearly with porosity [Nelson, 1994;Bryant et al, 1975;Neuzil, 1994]. We assign the permeability of the d6collement independently to represent the effects of channelized fluid flow.…”

Section: Site Descriptionmentioning

confidence: 99%

See 3 more Smart Citations

Episodic fluid flow in the Nankai accretionary complex: Timescale, geochemistry, flow rates, and fluid budget

Saffer

Bekins²

1998

J. Geophys. Res.

159

229

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Section: Model Equationsmentioning

confidence: 48%

Section: Discussionmentioning

confidence: 99%

Section: Sensitivity Analysis Of Permeabilities and Steady State Presmentioning

confidence: 99%

Section: Site Descriptionmentioning

confidence: 99%

See 2 more Smart Citations

Episodic fluid flow in the Nankai accretionary complex: Timescale, geochemistry, flow rates, and fluid budget

Saffer

Bekins²

1998

J. Geophys. Res.

159

229

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“…Numerical modelling shows that a hydraulic conductivity of 2-10~9 m/s is required for the 20 m thick confining layer overlying the artesian aquifer to explain a head of 1 m. This corresponds to a resistance (one over the leakance) of about 100,000 days. The inferred conductivity is very reasonable for a relatively pure marine clay (Neuzil, 1994). Clearly, if sediment loading were not considered, either the head distribution could not be explained, or a very complicated permeability distribution and flow regime would have to be assumed, with some narrow high-permeability conduit connecting the Burnside aquifer with an inland location with a high topographic head.…”

Section: Compaction-induced Flowmentioning

confidence: 96%

Geological processes and the management of groundwater resources in coastal areas

Kooi¹,

Groen²

2003

Netherlands Journal of Geosciences

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In this contribution, a case is made for the significance of sedimentation and sea-level change for groundwater management of coastal areas. In groundwater practice these geological processes are rarely considered. The role of sediment loading in causing anomalous fluid pressures and flow fields in relatively shallow aquifer systems is discussed and illustrated via both case studies and generic modelling studies. The role of sea-level changes in controlling current salinity distributions is discussed likewise. Central in the discussion is the concept of memory of groundwater systems, which provides the basic reason why processes that were operative in the geological past are still of relevance today. It is argued and shown that awareness and knowledge of the influence of sediment loading and sea level change on current hydrological conditions can lead to improved characterization of the distribution of hydraulic parameters and of the distribution of water quality in coastal areas. This improved characterization, in turn, serves to enhance the validity of impact assessment studies for the long-term development and management of those areas.

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Constraints on fluid flow processes in the Hellenic Accretionary Complex (eastern Mediterranean Sea) from numerical modeling

2014

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The dynamics of accretionary convergent margins are severely influenced by intense deformation and fluid expulsion. To quantify the fluid pressure and fluid flow velocities in the Hellenic subduction system, we set up 2‐D hydrogeological numerical models following two seismic reflection lines across the Mediterranean Ridge. These profiles bracket the along‐strike variation in wedge geometry: moderate compression and a >4 km thick underthrust sequence in the west versus enhanced compression and <1 km of downgoing sediment in the center. Input parameters were obtained from preexisting geophysical data, drill cores, and new geotechnical laboratory experiments. A permeability‐porosity relationship was determined by a sensitivity analysis, indicating that porosity and intrinsic permeability are small. This hampers the expulsion of fluids and leads to the build up of fluid overpressure in the deeper portion of the wedge and in the underthrust sediment. The loci of maximum fluid pressure are mainly controlled by the compactional fluid source, which generally decreases toward the backstop. However, pore pressure is still high at the decollement level at distances <100 km from the deformation front, either by the incorporation of low permeability evaporites or additional compaction of the wedge sediments in the two profiles. In the west, however, formation of a wide accretionary complex is facilitated by high pore pressure zones. When compared to other large accretionary complexes such as Nankai or Barbados, our results not only show broad similarities but also that near‐lithostatic pore pressures may be easier to maintain in the Hellenic Arc because of accentuated collision, some underthrust evaporates, and a thicker underthrust sequence.

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How permeable are clays and shales?

Cited by 561 publications

References 31 publications

Episodic fluid flow in the Nankai accretionary complex: Timescale, geochemistry, flow rates, and fluid budget

Episodic fluid flow in the Nankai accretionary complex: Timescale, geochemistry, flow rates, and fluid budget

Geological processes and the management of groundwater resources in coastal areas

Constraints on fluid flow processes in the Hellenic Accretionary Complex (eastern Mediterranean Sea) from numerical modeling

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