Abnormal pressures as hydrodynamic phenomena

Neuzil, Christopher E.

doi:10.2475/ajs.295.6.742

Cited by 265 publications

(238 citation statements)

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“…The variations around zero are only due to room temperature changes. cannot be interpreted as an "overpressure" (pressures exceeding the hydrostatic value, see review by Neuzil [1995]) generating diverging flow toward adjacent aquifers. Such erroneous interpretations can be avoided simply by considering the partial or hydrodynamic pressure gradient.…”

Section: Implications For Fluid Flowmentioning

confidence: 99%

What is the significance of pore pressure in a saturated shale layer?

Gonçalvès

Rousseau-Gueutin

Marsily

et al. 2010

Water Resources Research

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International audienceElectrostatic interactions, associated with negatively charged surfaces of clay minerals, produce a so-called "disjoining pressure" when diffuse layers overlap, i.e., at low porosity. Disjoining pressure is the pressure difference between the water in the clay pore space and that in a bulk solution at the same depth. Another widely used concept in clay-rocks is the "swelling pressure." It corresponds in fact to the macroscopic average of the disjoining pressure. This study proposes to determine the value of the swelling pressure of a natural material by a simple volume-averaging approach of the disjoining pressure, calculated for each clay mineral present in the material. The swelling pressure, which is dependent on the salinity of the pore fluid, is introduced into a hydrochemomechanical coupling, yielding a more general pressure diffusion equation. The results are compared to swelling pressure measurements for natural shale samples. The implications of this swelling pressure for water pressure measurements in natural formations are also discussed

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Section: Implications For Fluid Flowmentioning

confidence: 99%

What is the significance of pore pressure in a saturated shale layer?

Gonçalvès

Rousseau-Gueutin

Marsily

et al. 2010

Water Resources Research

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“…One example is the generation of deep subsurface rock fractures by anomalous fluid pressures. In sedimentary basins, fluid pressures may be elevated by many different processes [see Neuzil, 1995] and attain large magnitudes relative to hydrostatic, sometimes exceeding the least principal stress [McPherson and Bredehoeft, 2001]. The rate of pressure dissipation is governed by rock hydraulic diffusivity and the rate of pressure generation.…”

Section: Introductionmentioning

confidence: 99%

Direct simulation of fluid‐solid mechanics in porous media using the discrete element and lattice‐Boltzmann methods

Boutt¹,

Cook²,

McPherson³

et al. 2007

J. Geophys. Res.

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[1] A detailed understanding of the coupling between fluid and solid mechanics is important for understanding many processes in Earth sciences. Numerical models are a popular means for exploring these processes, but most models do not adequately handle all aspects of this coupling. This paper presents the application of a micromechanically based fluid-solid coupling scheme, lattice-Boltzmann discrete element method (LBDEM), for porous media simulation. The LBDEM approach couples the lattice-Boltzmann method for fluid mechanics and a discrete element method for solid mechanics. At the heart of this coupling is a previously developed boundary condition that has never been applied to coupled fluid-solid mechanics in porous media. Quantitative comparisons of model results to a one-dimensional analytical solution for fluid flow in a slightly deformable medium indicate a good match to the predicted continuum-scale fluid diffusion-like profile. Coupling of the numerical formulation is demonstrated through simulation of porous medium consolidation with the model capturing poroelastic behavior, such as the coupling between applied stress and fluid pressure rise. Finally, the LBDEM model is used to simulate the genesis and propagation of natural hydraulic fractures. The model provides insight into the relationship between fluid flow and propagation of fractures in strongly coupled systems. The LBDEM model captures the dominant dynamics of fluid-solid micromechanics of hydraulic fracturing and classes of problems that involve strongly coupled fluid-solid behavior.

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“…Water is expelled as sediments are squeezed tectonically and rapidly buried by tectonic thickening, reducing porosities from greater than The combination of low perme. abilities typical of marine sediments [e.g., Bryant,197•] and high fluid production rates in accretionary complexes [Neuzil, 1995;Screaton et al, 1990] In addition to mechanically induced dewatering caused by high burial rates, mineral dehydration and hydrocarbon generation become increasingly significant sources of pore fluid as buried sediments are exposed to higher temperatures. Low chloride and high methane concentrations observed at drilling sites document the role of these processes in fluid generation .…”

Section: Introductionmentioning

confidence: 99%