Topic
Permeability (earth sciences)
About: Permeability (earth sciences) is a research topic. Over the lifetime, 15424 publications have been published within this topic receiving 288535 citations.
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TL;DR: In this article, the effect of fluid flow on mixed-volatile reactions in metamorphic rocks is described by an expression derived from the standard equation for coupled chemical reaction and fluid-flow in porous media.
Abstract: The effect of fluid flow on mixed-volatile reactions in metamorphic rocks is described by an expression derived from the standard equation for coupled chemical-reaction and fluid-flow in porous media. If local mineral-fluid equilibrium is assumed, the expression quantitatively relates the time-integrated flux at any point in a flow-system to the progress of devolatilization reactions and the temperature- and pressure-gradients along the direction of flow. Model calculations indicate that rocks are generally devolatilized by fluids flowing uptemperature and/or down-pressure. Flow down-temperature typically results in hydration and carbonation of rocks. Time-integrated fluid fluxes implied by visible amounts of mineral products of devolatilization reactions are on the order of 5·102–5·104 mol/cm2. The model was applied to regionally metamorphosed impure carbonate rocks from south-central Maine, USA, to obtain estimates of fluid flux, flow-direction, and in-situ metamorphic-rock permeability from petrologic data. Calculated time-integrated fluxes are 104–106 cm3/cm2 at 400°–450° C, 3,500 bars. Fluid flowed from regions of low temperature to regions of high temperature at the peak of the metamorphic event. Using Darcy's Law and estimates for the duration of metamorphism and hydrologic head, calculated fluxes are 0.1–20·10-4 m/year and minimum permeabilities are 10-10–10-6 Darcy. The range of inferred permeability is in good agreement with published laboratory measurements of the permeability of metamorphic rocks.
148 citations
TL;DR: In this paper, the authors evaluate how single-phase permeability varies as a function of sample support for ripple laminated sandstone intercalated with mudstone, and identify three flow upscaling regimes that each require a different method for up-scaling: (1) layered systems where the arithmetic and harmonic averages are appropriate, (2) systems close to the percolation threshold, (3) discontinuous systems where an effective medium method provides the best estimate of permeability.
Abstract: Using a range of realistic 3D numerical lithofacies (dm-scale) models of ripple laminated sandstone intercalated with mudstone we evaluate how single-phase permeability varies as a function of sample support. The models represent a range of mudstone content which is typical for tidal deposits. Furthermore, the spatial distribution of flow barriers (i.e. mudstone) is not random, but governed by sedimentological rules giving a variable anisotropy ratio as a function of mudstone content. Both vertical and horizontal permeability are found to vary at small sample volumes, but these fluctuations reduce as the sample volume increases. The vertical permeability increases while the horizontal permeability is nearly constant as a function of sample support for small mudstone contents. For higher mudstone content, the horizontal permeability decreases while the vertical permeability is nearly constant as a function of sample support. We propose a criterion, based on a normalised standard deviation, to determine the Representative Elementary Volume (REV). The size of the REV is dependent on both the property measured (vertical and horizontal permeability) and the correlation lengths of the lithological elements (i.e. lithofacies). Based on this we identify three flow upscaling regimes that each require a different method for upscaling: (1) layered systems where the arithmetic and harmonic averages are appropriate, (2) systems close to the percolation threshold where a percolation model should be used, and (3) discontinuous systems where an effective medium method provides the best estimate of permeability. The work gives, by using numerical experiments on a range of heterogeneous systems, a new insight in determination of the REV for permeability at the lithofacies scale and its relation to sedimentological parameters.
147 citations
TL;DR: Longitudinal dispersion and permeability tests in the Darcy flow regime using uniform porous media consisting either of spheres or sand grains were performed in this article, and the results showed that the media was uniform and porous.
Abstract: Longitudinal dispersion and permeability tests were performed in the Darcy flow regime using uniform porous media consisting either of spheres or sand grains.
147 citations
TL;DR: In this paper, the authors explored the coal seams of Chinese coal seams with high gas content and low permeability and proposed to improve coal seams' permeability to achieve maximum extraction of coalbed methane.
Abstract: Chinese coal seams are characterized by high gas content and low permeability. The permeability of coal seams should be improved to achieve maximum extraction of coalbed methane. This study explore...
147 citations
TL;DR: In this article, the authors numerically investigated the heat production potential from hot dry rock by water circulating through two horizontal wells, based on the geological data of well DP23-1 under the enhanced geothermal system (EGS) project at Desert Peak geothermal field.
146 citations