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Showing papers on "Permeability (earth sciences) published in 1993"


Proceedings ArticleDOI
TL;DR: In this article, a new, practical and theoretically correct methodology is proposed for identi$cation and characterization of hydraulic units based on a modified Kozeny-Carmen equation and the concept of mean hydraulic raditis.
Abstract: Understanding complex variations in pare geomet~ within different Iithofacies is the key to improved reservoir description and exploitation. Core data provide in~ornration on various depositional and diagenetic controls on pore geometry. Variations in pore geometrical attributes in rum, de$ne the existenceof distinct zones(hydraulic units) with similar f?uid-jlow characteristics. Classic discrimination of mck types has been based on subjective geological observations and on empirical relationships between the log of permeability versus porosity. Howevec for any porosity within a given mck type,permeability can vary by several orders of nragnitnde, which indicates the existenceof severalflow units. In this papec a new, practical and theoretically correct methodology is proposedfor identi$cation and characterization of hydraulic units widtin mappable geological units (facies). The technique is based on a modified Kozeny-Carmen equation and the conceptof mean hydraulic raditis. The equation indicatesIhat for any hydraulic unit, a log-log p!ot of a “Reservoir Quality index,” (RQI), which is equal to 0.0314 ~. versus a “Normalized PorosityIndex” (+=) which is equal to WI-W should yield a straight line with a unit slope. 7he intercept of the unit slope line with +Z = 1, designated as the “FIow Zme Indicator” (M), is a unique parameter for each hydraulic unit. RQI, 4, and FZI are based on stressed potvsity and permeability data measuredon core samples.

878 citations


Journal ArticleDOI
TL;DR: In this article, the effect of stochastic soil permeability on confined seepage under water retaining structures has been studied, and the results of parametric studies to gauge the impact of the standard deviation and correlation structure of the permeability of soil on the output statistics relating to seepability quantities, exit gradients and uplift pressures are presented.
Abstract: The effect of stochastic soil permeability on confined seepage beneath water retaining structures has been studied. Random field concepts for the generation of soil permeability properties with a fixed mean, standard deviation and spatial correlation structure have been combined with finite element methods to perform Monte Carlo simulations of the seepage problem. Analyses have been performed for a dam with two cut-off walls. The results of parametric studies to gauge the effect of the standard deviation and correlation structure of the permeability on the output statistics relating to seepage quantities, exit gradients and uplift pressures are presented. In all cases, comparison is made with results that would be achieved on a deterministic basis. Flow rates and other quantities are shown to be affected significantly by the standard deviation and the correlation structure of soil permeability. L'article etudie l'influence de la permeabilite d'un sol stochastique sur l'infiltration confinee existant sous ...

212 citations


Book
31 Jul 1993
TL;DR: In this article, the authors present a model of fluid flow in a single discontinuity and quantify the percolation properties of the fluid flow through a given discontinuity in a rock.
Abstract: Rock and rock mass permeability. Rock discontinuity characterization. Fluid flow in a single discontinuity. Connectivity, scale effects and percolation theory. Permeability and depth in rock masses. Numerical methods of modelling flow. Index.

138 citations


Journal ArticleDOI
TL;DR: In this paper, the pore-scale geometric features of the model are found to be spatially correlated, and this departure from randomness significantly affects macroscopic properties such as permeability.
Abstract: Permeability is a critical parameter for the petroleum geologist. By simulating the processes of compaction and cementation in a model porous medium, we have gained a new understanding of how permeability is controlled in reservoir sandstones. This understanding can be used predictively for simple sandstones. The geometry of the model pore system is completely defined, so permeability can be calculated directly using a network model for flow. The calculation is based on first principles and is physically rigorous. In contrast to many previous efforts to predict permeability, there are no adjustable parameters in the calculations and no additional measurements or correlations (e.g., capillary pressure data or pore system data from thin sections) are required. The model-derived porosity-permeability trend for a compacted or quartz cemented sandstone, or a sandstone having a combination of these processes, closely matches measurements on Fontainebleau sandstone samples whose permeabilities span nearly five orders of magnitude. The model also correctly predicts mercury injection measurements of pore throat size distribution for the Fontainebleau sandstone. Pore-scale geometric features of the model are found to be spatially correlated, and this departure from randomness significantly affects macroscopic properties such as permeability. The agreement between predictions and measurements suggests that spatial correlation is inherent in granular porous media and consequently, uncorrelated (or arbitrarily correlated) models of transport in such media are unlikely to be physically representative. We also discuss extending the model to predict properties of more complicated rocks.

130 citations


Journal ArticleDOI
TL;DR: In this paper, the authors describe a conspicuous NTF signature entirely within a low-permeability shale in an eroded basin, which appears to be a lagging hydrodynamic response to mechanical rebound and cooling from erosion.
Abstract: Naturally transient flow (NTF) occurs when a groundwater regime fails to accommodate geologic changes. This paper describes a conspicuous NTF signature entirely within a low-permeability shale in an eroded basin. Flow in the shale appears to be a lagging hydrodynamic response to mechanical rebound and cooling from erosion; careful, long-term pressure measurements revealed a consistent pattern of low hydraulic head with the minimum within the shale. Available data are sufficient to rule out alternate causes of the pressure regime, and to construct a meaningful quantitative model of the effects of erosion. The shale behaves as a Kelvin substance in tests, but theoretical considerations suggest that its deformation during erosion mimics elastic behavior, permitting the model to be based on poroelasticity. Pressure patterns similar to that observed can be produced by incorporating into the model independent estimates of the shale's hydraulic, mechanical, and thermal properties and a reconstruction of the area's erosion history. The results confirm that local permeability is between 10−21 and 10−20 m2 (hydraulic conductivity between 10−14 and 10−13 m/s), in contrast to the higher regional permeability of 2×10−16 m2 (hydraulic conductivity of 2× 0−9 m/s) determined in an earlier study. Exploration techniques employed in this study could reveal similar NTF regimes in the future.

85 citations


Journal ArticleDOI
TL;DR: In this article, a straightforward procedure is developed for determining the general anisotropic in-plane permeability character of fiber preforms from constant flow rate mold filling experiments, based on the application of Darcy's law to a two-dimensional inplane flow situation.
Abstract: Fiber preform permeability has a strong influence on the resin impregna tion behavior during polymer composites fabrication. A straightforward procedure has been developed for determining the general anisotropic in-plane permeability character of fiber preforms from constant flow rate mold filling experiments. The procedure is based on the application of Darcy's law to a two-dimensional in-plane flow situation. From ex perimental data on changes in flow front position and inlet pressure with mold filling time, the components of the in-plane permeability tensor can be calculated directly using param eters obtained from two linear plots. Experimental data for a commercial fabric confirms the applicability of the procedure. The required equipment setup and the analytical proce dure are both uncomplicated in nature. The proposed method provides a simple solution to the measurement of permeability and comparison of different preforms for polymer composites application.

83 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the possibility that stress state- permeability relationships might be developed for clays within the framework of generalisations already made in the analysis and prediction of soil behaviour.
Abstract: This Technical Note investigates the possibility that stress state- permeability relationships might be developed for clays within the framework of generalisations already made in the analysis and prediction of soil behaviour. Consolidation and permeability tests carried out on red, brown, black cotton and bentonite soils, chosen for their varying liquid limits, are described. The results are presented and interpreted. For a given void ratio the experimental and predicted permeability coefficients showed a good correlation. The interchangeability of stress state and permeability is discussed.

79 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present two approximate models for describing the flow field within a porous particle contained in a fixed or fluidized bed, where a swarm model where a spherical porous particle of a specified permeability is contained in matrix of a different permeability that is equated to the overall bed permeability.

78 citations


Journal ArticleDOI
TL;DR: In this paper, a comparison of these measurements with estimates generated with five common methods showed that these methods are limited in their predictive capabilities, and thus these estimations may only be appropriately applied to drainage for the non wetting phase.
Abstract: Although the constitutive relationship of relative permeability as a function of saturation has been examined extensively in soil science and petroleum engineering, there is little information about this relationship for many systems encountered at hazardous waste sites. This lack of data has led to the use of estimation methods for relative permeability without verifying that they are indeed applicable to systems representative of hazardous waste sites. To assess the accuracy of methods commonly used for the prediction of two-phase relative permeabilities, drainage and imbibition relative permeabilities were measured for several organic liquid-water systems. A comparison of these measurements with estimates generated with five common methods showed that these methods are limited in their predictive capabilities. They estimated the relative permeability to the aqueous phase well, but failed to predict the low permeability to the organic liquid. For the relative permeability to the organic liquid to reach the predicted value of unity at the residual aqueous phase saturation, the effective permeabilities must be normalized by the permeability measured in the presence of residual water. The common estimation techniques make no provision for hysteresis. Since the aqueous phase showed little hysteresis, these estimations methods can be applied to both drainage and imbibition processes for this phase. However, the organic liquid phase showed hysteresis, and thus these techniques may only be appropriately applied to drainage for the non wetting phase.

69 citations


Journal ArticleDOI
TL;DR: In this paper, a network method is presented for the simulation of mercury intrusion and the calculation of the absolute permeability of porous media, which can be used for any porous medium.

67 citations


Journal ArticleDOI
TL;DR: In this article, a total aqueous chemical potential concept is presented that describes the driving potentials that operate during both phases of flow, and experimental methods are presented to determine the storage of water shale during the swelling phase and the permeabilities with steady-state flow and transient-flow techniques.
Abstract: Laboratory-derived permeability and pore-pressure data obtained for Wellington and Pierre shales are used to describe swelling pressure, and spalling types of wellbore instability. Tests showed that increased pore pressures can lead to wellbore failure. The laboratory pore-pressure information developed displays a time-dependent swelling process followed by a Darcy type of flow. A total aqueous chemical potential concept is presented that describes the driving potentials that operate during both phases of flow. Experimental methods are presented to determine the storage of water shale during the swelling phase and the permeabilities with steady-state-flow and transient-flow techniques. Permeability values measured under effective stresses up to 8,000 psi show the Wellington shale to have values as low as 0.30 [times] 10[sup [minus]6] md.

Journal ArticleDOI
TL;DR: In this article, an improved self-consistent method for estimating the permeability of an aligned fiber assembly, in both longitudinal and transverse directions, is presented, where the insertion is assumed to include open space surrounded by densely packed fibers.
Abstract: This paper presents an improved self-consistent method for estimating the permeability of an aligned fiber assembly, in both longitudinal and transverse directions. In this method an insertion is assumed to include open space surrounded by densely packed fibers. This improvement allows us to describe effectively the permeability of dense structures containing distributed voids. As used in self-consistent methods, the insertion is placed into a homogeneous medium with an unknown permeability. Stokes flow and Darcy flow are then considered, respectively, at different regions. Boundary and interface conditions as well as two consistency conditions, including the total amount of the flow and the dissipation energy, are applied accordingly. The permeability is solved from these considerations. This improved permeability model captures the flow characteristics of a fiber bundle. In the longitudinal flow case, the openings within a bundle due to disturbance dominate the flow path. In the transverse flow case, the gaps between neighboring fibers govern the flow resistance. The derived expression for the transverse permeability contains two variables, the averaged fiber volume fraction and the maximum packing efficiency, which adequately describe the status of a fiber bundle. These two variables can also be measured experimentally. The predictions agree with available data reported. The result for the longitudinal flow shows not only the influence of these two parameters, but also the very strong effect of the openings within the bundle on the permeability. This explains the significant differences between the data of idealized packings, such as square and hexagonal packing, and those measured from real fiber bundles. The comparison also provides an estimation of the average opening sizes within a fiber bundle as a function of fiber volume fraction. Numerical simulation results of previous studies are also used to verify this approach.

Journal ArticleDOI
TL;DR: In this paper, a continuous-time random-walk method is introduced for applications to transport processes in random media, which can be used to calculate the diffusivity of homogeneous mixtures of many components, with applications to effective permeability and conductivity measurements.
Abstract: A continuous-time random-walk method is introduced for applications to transport processes in random media. The method is efficient and is easily parallelizable. It can be used to calculate the diffusivity of homogeneous mixtures of many components, with applications to effective permeability and conductivity measurements. It is also applicable to diffusion-limited aggregation in random media and to determining connected regions of high permeability in geological models of petroleum reservoirs.

Journal ArticleDOI
TL;DR: In this paper, a simple cubic network model of 30 x 30 × 30 -30 bonds is used to identify the correct form of transport equations, and the duct hydraulic conductances are then obtained as a function of viscosity ratio and phase volume fraction using a finite element calculation.
Abstract: Two-phase flow in porous media is described based on the extended form of Darcy's law, which ignores momentum transfer at fluid-fluid interfaces. Two forms of corrections to this simple description have been proposed in the literature: on the relative permeability dependence on viscosity ratio; the other on the velocities assumed to be proportional to both phase pressure gradients and so introducing an additional saturation-dependent cross coefficient. In this article, to identify the correct form of transport equations, a simple cubic network model of 30 x 30 x 30 bonds is used. The cross section of the bonds is that of a four-cusp duct. The fluid interface in each duct is located by capillary equilibrium. The duct hydraulic conductances are then obtained as a function of viscosity ratio and phase volume fraction using a finite element calculation. These individual duct results are used in the network calculations for which a percolation algorithm is applied to simulate nonwetting phase displacing wetting phase, a process also known as initial drainage. Flow calculations show that both the nonwetting-phase relative permeability and the cross coefficient are strong functions of saturation and viscosity ratio. Also, the off-diagonal terms may contribute to a nonnegligible fraction of themore » flow. The proposed generalization of the Darcy equations is applicable to all problems involving multiphase flow in porous media. The current practices for relative permeability measurements and reservoir simulation may have to be reexamined in the context of the proposed transport equations.« less


Journal Article
TL;DR: In this article, the authors developed detailed data on aperture and phase structure from a transparent analog fracture, and measured the wetting phase relative permeability under steady-state conditions under unsaturated conditions.
Abstract: Fractures within geologic media can dominate the hydraulic properties of the system. Therefore, conceptual models used to assess the potential for radio-nuclide migration in unsaturated fractured rock such as that composing Yucca Mountain, Nevada, must be consistent with flow processes in individual fractures. A major obstacle to the understanding and simulation of unsaturated fracture flow is the paucity of physical data on both fracture aperture structure and relative permeability. An experimental procedure is developed for collecting detailed data on aperture and phase structure from a transparent analog fracture. To facilitate understanding of basic processes and provide a basis for development of effective property models, the simplest possible rough-walled fracture is used. Stable phase structures of varying complexity are created within the horizontal analog fracture. Wetting phase permeability is measured under steady-state conditions. A process based model for wetting phase relative permeability is then explored. Contributions of the following processes to reduced wetting phase permeability under unsaturated conditions are considered: reduction in cross-sectional flow area, increased path length, localized flow restriction, and preferential occupation of large apertures by the non-wetting phase.

Journal ArticleDOI
TL;DR: In this article, the authors measured the vertical hydraulic conductivity of a 15m-thick clay confining layer and found that it is approximately 10−5 cm s−1, up to 4 orders of magnitude higher than laboratory values for the same sediment.
Abstract: Installation of surface levees and subsurface slurry walls around a 1600-m by 950-m hazardous waste landfill in southeastern Louisiana has inadvertently converted the site into a large-scale permeameter. Differences in water levels in wells screened above and below a 15-m-thick clay “confining layer” define a vertical hydraulic gradient of +0.1. Basic climatological data permit calculation of a complete water budget for the site, including vertical recharge qz down through the clay. Cumulative precipitation over a 44-month period was 5.5 m, and recharge was over 1.0 m. The calculated vertical hydraulic conductivity of the clay sequence is approximately 10−5 cm s−1, up to 4 orders of magnitude higher than laboratory values for the same sediment. Intercalated sands and zones of pedogenic secondary porosity and fracturing developed during periods of subaerial weathering are apparently the dominant controls on vertical permeability, not the matrix properties of the clay.


Journal ArticleDOI
TL;DR: In this article, the pore structure, capillarity, water permeability, and electrical conductivity of Fontainebleau sandstone specimens were measured using laboratory equipment and techniques.
Abstract: We report laboratory measurements of pore structure, capillarity, water permeability, and electrical conductivity on Fontainebleau sandstone specimens. Experimental equipment and techniques are described. Water permeability measurements were performed on saturated cores with a 100 MPa permeameter. Various combinations of pore and confining pressures were used and an effective pressure law was determined. In addition, electrical conductivity of samples saturated with KCl brines was measured over a wide range of electrolyte conductivities (10−3 to 1 Sm−1). The well-known relationshipF=Φ−1 fits well our data, and empirical parameters such as the cementation exponent and tortuosity factor are derived. Differences between transport properties of the three types of sandstone are related to the microstructural characteristics of the pore network of each rock.

Journal ArticleDOI
TL;DR: In this paper, the authors delineate the extent of validity of Darcy's law, within the context of a more general theoretical framework, and show that there are conditions when Mixture Theory could predict results that provide a significant departure from those predicted by Darcy’s Law.
Abstract: The classical problem of the radial flow to a well in a confined horizontal aquifer is solved using two theories: (1) when the flow is based on Darcy’s law, and (2) when the flow is based on equations of the Continuum Theory of Mixtures. The latter reduce to Darcy’s law when the inertia of the fluid can be neglected, and when the viscosity of the fluid does not enter into the expression for the partial stress for the fluid. A comparison of the two solutions shows that there are conditions when Mixture Theory could predict results that provide a significant departure from those predicted by Darcy’s Law. In this paper we delineate the extent of validity of Darcy’s law, within the context of a more general theoretical framework. The results of our work indicate that Darcy’s law is indeed quite good for low flow rates for a fluid like water. However this is not the case for dense fluids, say oils or effluents, due to the inclusion of inertial effects in the equations of motions.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the relationship between the fractal character of hydraulic conductivity distribution and the statistics of unsaturated flow by means of Monte Carlo simulations of steady-state infiltration in soils with generated fractal permeability distribution.
Abstract: Stochastic analysis of flow and transport in soils usually assumes that the soil permeability is a stationary, homogeneous stochastic process. Some field data suggest, however, that permeability distributions may have a fractal character with long-range correlations. One such set of data is analyzed in this paper. We also investigate the relationship between the fractal character of hydraulic conductivity distribution and the statistics of unsaturated flow. This was studied by means of Monte Carlo simulations of steady-state infiltration in soils with generated fractal permeability distribution. The results of these simulations were compared to theoretical results obtained from spectral analysis of unsaturated flow.

Book
01 Jan 1993
TL;DR: In this article, the effects of permeability, frequency, and fluid distribution on the viscoelastic behavior of rock to seismic waves are investigated. But the authors consider wave-induced squirt fluid flow at two scales: (1) local microscopic flow at the smallest scale of saturation heterogeneity (e.g., within a single pore) and (2) macroscopic flow at a larger scale of fluid-saturated and dry patches.
Abstract: We investigate the effects of permeability, frequency, and fluid distribution on the viscoelastic behavior of rock. The viscoelastic response of rock to seismic waves depends on the relative motion of pore fluid with respect to the solid phase. Fluid motion depends, in part, on the internal wave‐induced pore pressure distribution that relates to the pore micro‐structure of rock and the scales of saturation. We consider wave‐induced squirt fluid flow at two scales: (1) local microscopic flow at the smallest scale of saturation heterogeneity (e.g., within a single pore) and (2) macroscopic flow at a larger scale of fluid‐saturated and dry patches. We explore the circumstances under which each of these mechanisms prevails. We examine such flows under the conditions of uniform confining (bulk) compression and obtain the effective dynamic bulk modulus of rock. The solutions are formulated in terms of generalized frequencies that depend on frequency, saturation, fluid and gas properties, and on the macroscopic ...

Journal ArticleDOI
TL;DR: Correlation analysis in conjunction with principal component and multiple-regression analyses were applied to laboratory chemical and petrographic data to assess the usefulness of these techniques in evaluating selected physical and hydraulic properties of carbonate-rock aquifers in central Pennsylvania as discussed by the authors.

Journal ArticleDOI
TL;DR: In this article, a simple correlative model is proposed for the estimation of sandstone permeability using data derived from image analysis of thin sections, and the model is empirical, and based on only two-dimensional image data.

Journal ArticleDOI
TL;DR: The change in hydraulic conductivity of saturated clays due to short-term and long-term exposure of organic chemicals to clays is investigated to explain the change in the hydraulic conductivities of contaminated soils as mentioned in this paper.
Abstract: The change in hydraulic conductivity of saturated clays due to short‐term and long‐term exposure of organic chemicals to clays is investigated to explain the change in hydraulic conductivity of contaminated soils. The long‐term exposure of soils to chemicals is simulated in a laboratory environment by premixing chemicals with soils. Under short‐term and simulated long‐term exposures of water soluble chemicals to soils, the hydraulic conductivities of laboratory consolidated clays are measured and reported. The permeability tests are performed using the both flexi‐wall and modified fixed‐wall permeameters with soil samples subjected to confining pressures. The fixed‐wall and flexi‐wall permeameters produced similar results. The short‐term permeability tests showed a change in hydraulic conductivity values but not the intrinsic permeabilities of soils. The simulated long‐term exposure of organic chemicals to soils showed a change in the soil structure and an increase in the intrinsic permeability of soils. ...

01 Jan 1993
TL;DR: In this paper, the authors studied the mechanism causing substantial settlement observed during and immediately after liquefaction in a centrifuge test, using resistivity measurements to characterize the soil structure.
Abstract: The mechanism causing the substantial settlement observed during and immediately after liquefaction in a centrifuge test is studied using resistivity measurements to characterize the soil structure. The permeability value at the point of initial liquefaction is shown to increase from the value at the initial state when the tortuosities and the pore shape factors at the appropriate states are used in the Kozeny-Carman equation. The mechanism causing the substantial increase in settlement is considered to be due to the increase in permeability. The higher the permeability, the higher is the rate of settlement and the larger is the incremental settlement in each time step. In addition, the increase in permeability causes the liquefaction front to propagate upwards faster and, therefore, the generation and dissipation processes affect a larger depth of the soil column during shaking, and hence, produces a larger settlement. The use of a modified permeability in a fully coupled finite element code, DYSAC2, provides a good measure of the observed settlement. (A) For the covering abstract see IRRD 859983.

Journal ArticleDOI
TL;DR: In this article, the authors examined the coupled problem of fluid overpressure build-up, permeability and local mass transfer in the crust by means of an advection-diffusion equation derived from the poro-elastic theory.

Journal ArticleDOI
TL;DR: In this paper, a simple technique is proposed to obtain approximate analytical solutions to the diffusive problem with pressure-dependent formation permeability, which can result in significant errors in the estimation of temporal and spatial variation of pressure.
Abstract: Fluid flow in hydrocarbon reservoirs and groundwater aquifers is traditionally studied by assuming that the formation permeability is constant. Such an assumption can, however, result in significant errors in the estimation of temporal and spatial variation of pressure when the formation permeability is pressure sensitive. In the present study a simple technique is proposed to obtain approximate analytical solutions to the diffusive problem with pressure-dependent formation permeability. A constant pressure test in an infinitely large system is considered. Solutions to the flow problem in linear, cylindrical, and spherical systems are derived. These solutions are then compared with the corresponding constant permeability solutions and are related to a dimensionless parameter αD which is a measure of the pressure sensitivity of the formation permeability. In the present analysis the parameter αD is used to define a simple relationship between the pressure-sensitive and constant permeability solutions for all three geometries. It is shown that the constant permeability solutions may underestimate the pressure distribution by approximately 10% or more for a spherical system for αD, = 0.2. Moreover, it is demonstrated that the pressure difference between the two solutions would be most significant within a distance of a few well bore radii around the well bore and at large times. For a cylindrical system the maximum pressure difference is located at the well bore and is approximately 10% for αD = 0.2.

Journal ArticleDOI
James S. Reed1
TL;DR: In this article, the experimental aqueous permeability of sets of porous powder compacts varying widely in porosity and pore structure was shown to be much better described in terms of the linear mean pore size determined from mercury penetration porosimetry.
Abstract: Liquid transport through the interstices of packed particles is commonly described using the Carmen–Kozeny mean hydraulic radius model, which calibrates the effective pore dimension from mean macroscopic parameters. However, the experimental aqueous permeability of sets of porous powder compacts varying widely in porosity and pore structure was shown to be much better described in terms of the linear mean pore size determined from mercury penetration porosimetry. Here it is shown that the latter model is supported by studies of the permeability of porous rock and percolation theory.

Journal ArticleDOI
TL;DR: In this article, the authors measured the air permeability of pre-gelatinized flour dough as a function of porosity (0.10-0.60), moisture content (15-50%, wet basis), and fat content (0-6%).
Abstract: Permeability of air through porous pre-gelatinized flour dough was measured as a function of porosity (0.10–0.60), moisture content (15–50%, wet basis), and fat content (0–6%). At free stream velocities <2 cm/sec, flow rate and pressure drop followed Darcy's law for flow through porous media. Permeability values ranged from 0.02 darcies at 0.10 porosity to about 23 darcies at 0.60 porosity. Permeability of dough does not follow the Kozeny model for granular materials, possibly due to differences in tortuosity between dough and granular materials. Moisture content <50% and fat content to 6% did not directly affect permeability.