Insights into fluid flow and environmental conditions present in deep-sea hydrothermal vent deposits from measurements of permeability and porosity

Science.gov (United States)

Gribbin, J. L.; Zhu, W.; Tivey, M. K.

2008-12-01

Evolution of permeability-porosity relationships (EPPRs) of different seafloor vent deposit sample types provide crucial information about how fluid flows within the deposits. In this study, we conducted permeability and porosity measurements on a wide range of vent sample types recovered from many different active seafloor vent fields. The sample set includes chalcopyrite-lined black smoker chimneys, Zn-rich diffusing spires (including white smokers), flanges/slabs/crusts (i.e., plate-like deposits that overlie pooled fluid), massive anhydrite, and cores recovered from the sides of vent structures. Using a probe permeameter, permeability measurements were systematically taken of each sample along several orientations. The measured permeability ranges over 6 orders of magnitude from 10-14 to 10-8 m2. Our data indicate that in general massive anhydrite samples are the least permeable with a mean at ~10-13 m2 and the samples from Zn-rich diffusing spires that were actively venting when collected are the most permeable with a mean at ~10-11 m2. With a mean at 10-11.5 m2, permeability data of flanges/slabs/crusts span over 4 orders of magnitude from 10-13 to 10-9 m2, the largest spread among all sample types tested. Permeability values of the outer portions of relict spires, ranging from ~10-13 m2 to 10-9.5 m2, displayed clear anisotropic trends: permeability along the radial directions is higher than that along the axial direction. Black smokers exhibit a strong layered heterogeneity, where inner chalcopyrite linings were significantly less permeable than outermost layers. To conduct porosity and directional permeability measurements, cylindrical cores will be taken from these vent samples. We will examine whether different sample types, or portions of samples, exhibit distinct permeability-porosity relationships, and will then use micro-structural observations of the cores to examine chimney growth processes (e.g., mineral deposition or cracking) that likely result

OBSERVATION AND ANALYSIS OF A PRONOUNCED PERMEABILITY AND POROSITY SCALE-EFFECT IN UNSATURATED FRACTURED TUFF

Energy Technology Data Exchange (ETDEWEB)

V. VESSELINOV; ET AL

2001-01-01

Over 270 single-hole (Guzman et al., 1996) and 44 cross-hole pneumatic injection tests (Illman et al., 1998; Illman, 1999) have been conducted at the Apache Leap Research Site (ALRS) near Superior, Arizona. They have shown that the pneumatic pressure behavior of fractured tuff at the site is amenable to analysis by methods which treat the rock as a continuum on scales ranging from meters to tens of meters, and that this continuum is representative primarily of interconnected fractures. Both the single-hole and cross-hole test results are free of skin effect. Single-hole tests have yielded estimates of air permeability at various locations throughout the tested rock volume, on a nominal support scale of about 1 m. The corresponding log permeability data exhibit spatial behavior characteristic of a random fractal and yield a kriged estimate of how these 1-m scale log permeabilities vary in three-dimensional space (Chen et al., 2000). Cross-hole tests have been analyzed by means of a three-dimensional inverse model (Vesselinov et al., 2000) in two ways: (a) by interpreting pressure records from individual borehole monitoring intervals, one at a time, while treating the rock as if it was spatially uniform; and (b) by using the inverse model to interpret pressure records from multiple tests and borehole monitoring intervals simultaneously, while treating the rock as a random fractal characterized by a power variogram. The first approach has yielded equivalent air permeabilities and air-filled porosities for a rock volume characterized by a length-scale of several tens of meters. Comparable results have been obtained by means of type-curves (Illman and Neuman, 2001). The second approach amounts to three-dimensional pneumatic tomography, or stochastic imaging, of the rock. It has yielded a high-resolution geostatistical estimate of how air permeability and air-filled porosity, defined over grid blocks having a length-scale of 1 m, vary throughout the modeled rock volume

Acoustic properties in travertines and their relation to porosity and pore types

NARCIS (Netherlands)

Soete, J.; Kleipool, L.M.; Claes, H.; Claes, S.; Hamaekers, H.; Kele, S.; Özkul, M.; Foubert, A.; Reijmer, J.J.G.; Swennen, R.

2015-01-01

Sonic velocities of Pleistocene travertines were measured under variable confining pressures. Combined with petrographical characteristics and petrophysical data, i.e. porosity, permeability and density, it was determined that travertine porosity, pore types and cementation control

Porosity and permeability determination of organic-rich Posidonia shales based on 3-D analyses by FIB-SEM microscopy

Science.gov (United States)

Grathoff, Georg H.; Peltz, Markus; Enzmann, Frieder; Kaufhold, Stephan

2016-07-01

The goal of this study is to better understand the porosity and permeability in shales to improve modelling fluid and gas flow related to shale diagenesis. Two samples (WIC and HAD) were investigated, both mid-Jurassic organic-rich Posidonia shales from Hils area, central Germany of different maturity (WIC R0 0.53 % and HAD R0 1.45 %). The method for image collection was focused ion beam (FIB) microscopy coupled with scanning electron microscopy (SEM). For image and data analysis Avizo and GeoDict was used. Porosity was calculated from segmented 3-D FIB based images and permeability was simulated by a Navier Stokes-Brinkman solver in the segmented images. Results show that the quantity and distribution of pore clusters and pores (≥ 40 nm) are similar. The largest pores are located within carbonates and clay minerals, whereas the smallest pores are within the matured organic matter. Orientation of the pores calculated as pore paths showed minor directional differences between the samples. Both samples have no continuous connectivity of pore clusters along the axes in the x, y, and z direction on the scale of 10 to 20 of micrometer, but do show connectivity on the micrometer scale. The volume of organic matter in the studied volume is representative of the total organic carbon (TOC) in the samples. Organic matter does show axis connectivity in the x, y, and z directions. With increasing maturity the porosity in organic matter increases from close to 0 to more than 5 %. These pores are small and in the large organic particles have little connection to the mineral matrix. Continuous pore size distributions are compared with mercury intrusion porosimetry (MIP) data. Differences between both methods are caused by resolution limits of the FIB-SEM and by the development of small pores during the maturation of the organic matter. Calculations show no permeability when only considering visible pores due to the lack of axis connectivity. Adding the organic matter with a

Gas-liquid Relative Permeability Estimation in 2D Porous Media by Lattice Boltzmann Method: Low Viscosity Ratio 2D LBM Relative Permeability

Directory of Open Access Journals (Sweden)

Sadegh Mahmoudi

2013-04-01

Full Text Available This work is a primary achievement in studying the CO2 and N2–oil systems. To predict gas-liquid relative permeability curves, a Shan-Chen type multicomponent multiphase lattice Boltzmann model for two-phase flow through 2D porous media is developed. Periodic and bounce back boundary conditions are applied to the model with the Guo scheme for the external body force (i.e., the pressure gradient. The influence of relationship between cohesion and adsorption parameters and the interfacial tension values in Young's equation, pore structure (micro scan image derived porous media response is compared with corresponding porosity and permeability ideal sphere pack structure, and saturation distribution on relative permeability curves are studied with the aim to achieve the realistic stable condition for the simulation of gas-liquid systems with a low viscosity ratio.

Investigating the effects of rock porosity and permeability on the performance of nitrogen injection into a southern Iranian oil reservoirs through neural network

Science.gov (United States)

Gheshmi, M. S.; Fatahiyan, S. M.; Khanesary, N. T.; Sia, C. W.; Momeni, M. S.

2018-03-01

In this work, a comprehensive model for Nitrogen injection into an oil reservoir (southern Iranian oil fields) was developed and used to investigate the effects of rock porosity and permeability on the oil production rate and the reservoir pressure decline. The model was simulated and developed by using ECLIPSE300 software, which involved two scenarios as porosity change and permeability changes in the horizontal direction. We found that the maximum pressure loss occurs at a porosity value of 0.07, which later on, goes to pressure buildup due to reservoir saturation with the gas. Also we found that minimum pressure loss is encountered at porosity 0.46. Increases in both pressure and permeability in the horizontal direction result in corresponding increase in the production rate, and the pressure drop speeds up at the beginning of production as it increases. However, afterwards, this pressure drop results in an increase in pressure because of reservoir saturation. Besides, we determined the regression values, R, for the correlation between pressure and total production, as well as for the correlation between permeability and the total production, using neural network discipline.

Using soft computing techniques to predict corrected air permeability using Thomeer parameters, air porosity and grain density

Science.gov (United States)

Nooruddin, Hasan A.; Anifowose, Fatai; Abdulraheem, Abdulazeez

2014-03-01

Soft computing techniques are recently becoming very popular in the oil industry. A number of computational intelligence-based predictive methods have been widely applied in the industry with high prediction capabilities. Some of the popular methods include feed-forward neural networks, radial basis function network, generalized regression neural network, functional networks, support vector regression and adaptive network fuzzy inference system. A comparative study among most popular soft computing techniques is presented using a large dataset published in literature describing multimodal pore systems in the Arab D formation. The inputs to the models are air porosity, grain density, and Thomeer parameters obtained using mercury injection capillary pressure profiles. Corrected air permeability is the target variable. Applying developed permeability models in recent reservoir characterization workflow ensures consistency between micro and macro scale information represented mainly by Thomeer parameters and absolute permeability. The dataset was divided into two parts with 80% of data used for training and 20% for testing. The target permeability variable was transformed to the logarithmic scale as a pre-processing step and to show better correlations with the input variables. Statistical and graphical analysis of the results including permeability cross-plots and detailed error measures were created. In general, the comparative study showed very close results among the developed models. The feed-forward neural network permeability model showed the lowest average relative error, average absolute relative error, standard deviations of error and root means squares making it the best model for such problems. Adaptive network fuzzy inference system also showed very good results.

A fractal model for predicting permeability and liquid water relative permeability in the gas diffusion layer (GDL) of PEMFCs

Science.gov (United States)

He, Guangli; Zhao, Zongchang; Ming, Pingwen; Abuliti, Abudula; Yin, Caoyong

In this study, a fractal model is developed to predict the permeability and liquid water relative permeability of the GDL (TGP-H-120 carbon paper) in proton exchange membrane fuel cells (PEMFCs), based on the micrographs (by SEM, i.e. scanning electron microscope) of the TGP-H-120. Pore size distribution (PSD), maximum pore size, porosity, diameter of the carbon fiber, pore tortuosity, area dimension, hydrophilicity or hydrophobicity, the thickness of GDL and saturation are involved in this model. The model was validated by comparison between the predicted results and experimental data. The results indicate that the water relative permeability in the hydrophobicity case is much higher than in the hydrophilicity case. So, a hydrophobic carbon paper is preferred for efficient removal of liquid water from the cathode of PEMFCs.

Permeability, porosity, dispersion-, diffusion-, and sorption characteristics of chalk samples from Erslev, Mors, Denmark

International Nuclear Information System (INIS)

Carlsen, L.; Batsberg, W.; Skytte Jensen, B.; Bo, P.

1981-08-01

A series of chalk samples from the cretaceous formation overlying the Erslev salt dome have been studied in order to establish permeabilities, porosities, dispersion-, diffusion-, and sorption characteristics of the chalk, Predominantly the investigations have been carried out by application of a liquid chromatographic technique. The chalk was found to be porous (epsilon approximately 0.4), however, of rather low permeability (k approximately 10 -7 cm/sec). It was found that the material exhibits a retarding effect on the migration of cationic species as Cs + , Sr 2+ , Co 2+ , and Eu 3+ , whereas anionic species as Cl - and TcO - 4 move with the water front. The geochemical implications are discussed. (author)

Fault-controlled permeability and fluid flow in low-porosity crystalline rocks: an example from naturally fractured geothermal systems in the Southern Andes

Science.gov (United States)

Arancibia, G.; Roquer, T.; Sepúlveda, J.; Veloso, E. A.; Morata, D.; Rowland, J. V.

2017-12-01

Fault zones can control the location, emplacement, and evolution of economic mineral deposits and geothermal systems by acting as barriers and/or conduits to crustal fluid flow (e.g. magma, gas, oil, hydro-geothermal and groundwater). The nature of the fault control permeability is critical in the case of fluid flow into low porosity/permeability crystalline rocks, since structural permeability provides the main hydraulic conductivity to generate a natural fractured system. However, several processes accompanying the failure of rocks (i.e. episodic permeability given by cycling ruptures, mineral precipitation from fluids in veins, dissolution of minerals in the vicinity of a fracture) promote a complex time-dependent and enhancing/reducing fault-controlled permeability. We propose the Southern Volcanic Zone (Southern Andes, Chile) as a case study to evaluate the role of the structural permeability in low porosity crystalline rocks belonging to the Miocene North Patagonian Batholith. Recently published studies propose a relatively well-constrained first-order role of two active fault systems, the arc-parallel (NS to NNE trending) Liquiñe Ofqui Fault System and the arc-oblique (NW trending) Andean Transverse Fault Zones, in fluid flow at crustal scales. We now propose to examine the Liquiñe ( 39°S) and Maihue ( 40°S) areas as sites of interaction between these fault systems, in order to evaluate a naturally fractured geothermal system. Preliminary results indicate upwelling of thermal water directly from fractured granite or from fluvial deposits overlying granitoids. Measured temperatures of thermal springs suggest a low- to medium-enthalpy system, which could potentially be harnessed for use in geothermal energy applications (e.g. heating, wood dryer and green house), which are much needed in Southern Chile. Future work will aim to examine the nature of structural permeability from the regional to the microscopic scale connecting the paleo- and current- fluid

Influence of local porosity and local permeability on the performances of a polymer electrolyte membrane fuel cell

Energy Technology Data Exchange (ETDEWEB)

Akiki, Tilda [Universite Saint Esprit Kaslik (Lebanon); Universite de Technologie de Belfort-Montbeliard, FCLAB Institute for Research on Fuel Cell Systems, 90010 Belfort (France); Charon, Willy; Iltchev, Marie-Christine; Kouta, Raed [Universite de Technologie de Belfort-Montbeliard, FCLAB Institute for Research on Fuel Cell Systems, 90010 Belfort (France); Accary, Gilbert [Universite Saint Esprit Kaslik (Lebanon)

2010-08-15

In the literature, many models and studies focused on the steady-state aspect of fuel cell systems while their dynamic transient behavior is still a wide area of research. In the present paper, we study the effects of mechanical solicitations on the performance of a proton exchange membrane fuel cell as well as the coupling between the physico-chemical phenomena and the mechanical behavior. We first develop a finite element method to analyze the local porosity distribution and the local permeability distribution inside the gas diffusion layer induced by different pressures applied on deformable graphite or steel bipolar plates. Then, a multi-physical approach is carried out, taking into account the chemical phenomena and the effects of the mechanical compression of the fuel cell, more precisely the deformation of the gas diffusion layer, the changes in the physical properties and the mass transfer in the gas diffusion layer. The effects of this varying porosity and permeability fields on the polarization and on the power density curves are reported, and the local current density is also investigated. Unlike other studies, our model accounts for a porosity field that varies locally in order to correctly simulate the effect of an inhomogeneous compression in the cell. (author)

Electrokinetic effects and fluid permeability

International Nuclear Information System (INIS)

Berryman, J.G.

2003-01-01

Fluid permeability of porous media depends mainly on connectivity of the pore space and two physical parameters: porosity and a pertinent length-scale parameter. Electrical imaging methods typically establish connectivity and directly measure electrical conductivity, which can then often be related to porosity by Archie's law. When electrical phase measurements are made in addition to the amplitude measurements, information about the pertinent length scale can then be obtained. Since fluid permeability controls the ability to flush unwanted fluid contaminants from the subsurface, inexpensive maps of permeability could improve planning strategies for remediation efforts. Detailed knowledge of fluid permeability is also important for oil field exploitation, where knowledge of permeability distribution in three dimensions is a common requirement for petroleum reservoir simulation and analysis, as well as for estimates on the economics of recovery

Permeability of gypsum samples dehydrated in air

Science.gov (United States)

Milsch, Harald; Priegnitz, Mike; Blöcher, Guido

2011-09-01

We report on changes in rock permeability induced by devolatilization reactions using gypsum as a reference analog material. Cylindrical samples of natural alabaster were dehydrated in air (dry) for up to 800 h at ambient pressure and temperatures between 378 and 423 K. Subsequently, the reaction kinetics, so induced changes in porosity, and the concurrent evolution of sample permeability were constrained. Weighing the heated samples in predefined time intervals yielded the reaction progress where the stoichiometric mass balance indicated an ultimate and complete dehydration to anhydrite regardless of temperature. Porosity showed to continuously increase with reaction progress from approximately 2% to 30%, whilst the initial bulk volume remained unchanged. Within these limits permeability significantly increased with porosity by almost three orders of magnitude from approximately 7 × 10-19 m2 to 3 × 10-16 m2. We show that - when mechanical and hydraulic feedbacks can be excluded - permeability, reaction progress, and porosity are related unequivocally.

Permeability, porosity and compressive strength of self-compacting concrete

Directory of Open Access Journals (Sweden)

Valcuende, M.O.

2005-12-01

Full Text Available Most deterioration affecting the durability of self-compacting concrete structures is mediated by water penetration in the concrete, a condition related to its porous structure. The present study analyzes these two factors. To this end, two types of concrete were prepared, a self-compacting and a traditional vibrated concrete, with different W/C ratios and different types of cement. The results of low-pressure water testing to evaluate permeability and analyses to determine compressive strength and pore size distribution showed that self-compacting concrete has lower capillary porosity than traditional concrete, which would explain its greater resistance to water penetration. Such concrete likewise reached higher strength values, except where large proportions of lime powder with low sand equivalents were used in its manufacture, when lower strength was recorded. Lastly, the depth of water penetration and compressive strength were found to be linearly correlated. That correlation was seen to depend, in turn, on the type of concrete, since for any given strength level, self-compacting concrete was less permeable than the traditional material.

En este trabajo experimental se estudia la penetración de agua en hormigones autocompactables, analizando al mismo tiempo su estructura porosa, pues gran parte de los procesos de deterioro que afectan a la durabilidad de las estructuras están condicionados por estos dos aspectos. Para ello se han fabricado dos tipos de hormigones, uno autocompactable y otro tradicional vibrado, con diferentes relaciones A/C y distintos tipos de cemento. Tras determinar la permeabilidad al agua bajo presión, la resistencia a compresión y las distribuciones de tamaño de poro, los resultados obtenidos ponen de manifiesto que los hormigones autocompactables presentan menor porosidad capilar que los tradicionales, lo que les confiere mejores prestaciones frente a la penetración de agua. Asimismo, dichos hormigones

Are porosity and permeability seismic structural parameter? An old idea is presented and scrutinized; Sind Porositaet und Permeabilitaet seismische Strukturparameter? Eine alte Idee kurz vorgestellt und hinterfragt

Energy Technology Data Exchange (ETDEWEB)

Fertig, J. [Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). Inst. fuer Geophysik

2008-10-23

The exploration of hydrocarbons is confronted with the penetration into ever larger depths with increasingly more unfavorable reservoir characteristics. That means lower porosities and permeabilities. The geometry of a tectonic formation is a substantial size for the gap formation. It is expected that the observable curvature of a rock formation stands in direct connection with porosity and permeability of the rock. Under this aspect, the behaviour of a rock formation is examined at the demand above the yield strength by means of theoretical approaches from fracture mechanics. The author of the available contribution comes to the result: Secondary porosity is directly proportional to the curvature of the formation. In contrast to this, the secondary permeability is proportional to the third power of the curvature of the formation.

Lattice Boltzmann simulation of dissolution-induced changes in permeability and porosity in 3D CO2 reactive transport

Science.gov (United States)

Tian, Zhiwei; Wang, Junye

2018-02-01

Dissolution and precipitation of rock matrix are one of the most important processes of geological CO2 sequestration in reservoirs. They change connections of pore channels and properties of matrix, such as bulk density, microporosity and hydraulic conductivity. This study builds on a recently developed multi-layer model to account for dynamic changes of microporous matrix that can accurately predict variations in hydraulic properties and reaction rates due to dynamic changes in matrix porosity and pore connectivity. We apply the model to simulate the dissolution and precipitation processes of rock matrix in heterogeneous porous media to quantify (1) the effect of the reaction rate on dissolution and matrix porosity, (2) the effect of microporous matrix diffusion on the overall effective diffusion and (3) the effect of heterogeneity on hydraulic conductivity. The results show the CO2 storage influenced by factors including the matrix porosity change, reaction front movement, velocity and initial properties. We also simulated dissolution-induced permeability enhancement as well as effects of initial porosity heterogeneity. The matrix with very low permeability, which can be unresolved on X-ray CT, do contribute to flow patterns and dispersion. The concentration of reactant H+ increases along the main fracture paths where the flow velocity increases. The product Ca++ shows the inversed distribution pattern against the H+ concentration. This demonstrates the capability of this model to investigate the complex CO2 reactive transport in real 3D heterogeneous porous media.

Relationship between micro-porosity, water permeability and mechanical behavior in scaffolds for cartilage engineering.

Science.gov (United States)

Vikingsson, L; Claessens, B; Gómez-Tejedor, J A; Gallego Ferrer, G; Gómez Ribelles, J L

2015-08-01

In tissue engineering the design and optimization of biodegradable polymeric scaffolds with a 3D-structure is an important field. The porous scaffold provide the cells with an adequate biomechanical environment that allows mechanotransduction signals for cell differentiation and the scaffolds also protect the cells from initial compressive loading. The scaffold have interconnected macro-pores that host the cells and newly formed tissue, while the pore walls should be micro-porous to transport nutrients and waste products. Polycaprolactone (PCL) scaffolds with a double micro- and macro-pore architecture have been proposed for cartilage regeneration. This work explores the influence of the micro-porosity of the pore walls on water permeability and scaffold compliance. A Poly(Vinyl Alcohol) with tailored mechanical properties has been used to simulate the growing cartilage tissue inside the scaffold pores. Unconfined and confined compression tests were performed to characterize both the water permeability and the mechanical response of scaffolds with varying size of micro-porosity while volume fraction of the macro-pores remains constant. The stress relaxation tests show that the stress response of the scaffold/hydrogel construct is a synergic effect determined by the performance of the both components. This is interesting since it suggests that the in vivo outcome of the scaffold is not only dependent upon the material architecture but also the growing tissue inside the scaffold׳s pores. On the other hand, confined compression results show that compliance of the scaffold is mainly controlled by the micro-porosity of the scaffold and less by hydrogel density in the scaffold pores. These conclusions bring together valuable information for customizing the optimal scaffold and to predict the in vivo mechanical behavior. Copyright © 2015 Elsevier Ltd. All rights reserved.

Permeability of porour rhyolite

Science.gov (United States)

Cashman, K.; Rust, A.; Wright, H.; Roberge, J.

2003-04-01

The development of permeability in bubble-bearing magmas determines the efficiency of volatile escape during their ascent through volcanic conduits, which, in turn, controls their explosive potential. As permeability requires bubble connectivity, relationships between permeability and porosity in silicic magmas must be controlled by the formation, growth, deformation and coalescence of their constituent bubbles. Although permeability data on porous volcanic pyroclasts are limited, the database can be greatly extended by including data for ceramic and metallic foams1. Several studies indicate that a single number does not adequately describe the permeability of a foam because inertial effects, which predominate at high flow rates, cause deviations from Darcy's law. These studies suggest that permeability is best modeled using the Forschheimer equation to determine both the Darcy permeability (k1) and the non-Darcian (k2) permeability. Importantly, at the high porosities of ceramic foams (75-95%), both k1 and k2 are strongly dependent on pore size and geometry, suggesting that measurement of these parameters provides important information on foam structure. We determined both the connected porosity (by He-pycnometry) and the permeability (k1 and k2) of rhyolitic samples having a wide range in porosity (22-85%) and vesicle textures. In general, these data support previous observations of a power law relationship between connected porosity and Darcy permeability2. In detail, variations in k1 increase at higher porosities. Similarly, k2 generally increases in both mean and standard deviation with increasing porosity. Measurements made on three mutually perpendicular cores from individual pumice clasts suggest that some of the variability can be explained by anisotropy in the vesicle structure. By comparison with ceramic foams, we suggest that the remaining variability results from differences either in average vesicle size or, more likely, in the size of apertures

Multiple technologies applied to characterization of the porosity and permeability of the Biscayne aquifer, Florida

Science.gov (United States)

Cunningham, K.J.; Sukop, M.C.

2011-01-01

Research is needed to determine how seepage-control actions planned by the Comprehensive Everglades Restoration Plan (CERP) will affect recharge, groundwater flow, and discharge within the dual-porosity karstic Biscayne aquifer where it extends eastward from the Everglades to Biscayne Bay. A key issue is whether the plan can be accomplished without causing urban flooding in adjacent populated areas and diminishing coastal freshwater flow needed in the restoration of the ecologic systems. Predictive simulation of groundwater flow is a prudent approach to understanding hydrologic change and potential ecologic impacts. A fundamental problem to simulation of karst groundwater flow is how best to represent aquifer heterogeneity. Currently, U.S. Geological Survey (USGS) researchers and academic partners are applying multiple innovative technologies to characterize the spatial distribution of porosity and permeability within the Biscayne aquifer.

Porosity, permeability and 3D fracture network characterisation of dolomite reservoir rock samples.

Science.gov (United States)

Voorn, Maarten; Exner, Ulrike; Barnhoorn, Auke; Baud, Patrick; Reuschlé, Thierry

2015-03-01

With fractured rocks making up an important part of hydrocarbon reservoirs worldwide, detailed analysis of fractures and fracture networks is essential. However, common analyses on drill core and plug samples taken from such reservoirs (including hand specimen analysis, thin section analysis and laboratory porosity and permeability determination) however suffer from various problems, such as having a limited resolution, providing only 2D and no internal structure information, being destructive on the samples and/or not being representative for full fracture networks. In this paper, we therefore explore the use of an additional method - non-destructive 3D X-ray micro-Computed Tomography (μCT) - to obtain more information on such fractured samples. Seven plug-sized samples were selected from narrowly fractured rocks of the Hauptdolomit formation, taken from wellbores in the Vienna basin, Austria. These samples span a range of different fault rocks in a fault zone interpretation, from damage zone to fault core. We process the 3D μCT data in this study by a Hessian-based fracture filtering routine and can successfully extract porosity, fracture aperture, fracture density and fracture orientations - in bulk as well as locally. Additionally, thin sections made from selected plug samples provide 2D information with a much higher detail than the μCT data. Finally, gas- and water permeability measurements under confining pressure provide an important link (at least in order of magnitude) towards more realistic reservoir conditions. This study shows that 3D μCT can be applied efficiently on plug-sized samples of naturally fractured rocks, and that although there are limitations, several important parameters can be extracted. μCT can therefore be a useful addition to studies on such reservoir rocks, and provide valuable input for modelling and simulations. Also permeability experiments under confining pressure provide important additional insights. Combining these and

Effects of specific surface area and porosity on cube counting fractal dimension, lacunarity, configurational entropy, and permeability of model porous networks: Random packing simulations and NMR micro-imaging study

Science.gov (United States)

Lee, Bum Han; Lee, Sung Keun

2013-07-01

Despite the importance of understanding and quantifying the microstructure of porous networks in diverse geologic settings, the effects of the specific surface area and porosity on the key structural parameters of the networks have not been fully understood. We performed cube-counting fractal dimension (Dcc) and lacunarity analyses of 3D porous networks of model sands and configurational entropy analysis of 2D cross sections of model sands using random packing simulations and nuclear magnetic resonance (NMR) micro-imaging. We established relationships among porosity, specific surface area, structural parameters (Dcc and lacunarity), and the corresponding macroscopic properties (configurational entropy and permeability). The Dcc of the 3D porous networks increases with increasing specific surface area at a constant porosity and with increasing porosity at a constant specific surface area. Predictive relationships correlating Dcc, specific surface area, and porosity were also obtained. The lacunarity at the minimum box size decreases with increasing porosity, and that at the intermediate box size (∼0.469 mm in the current model sands) was reproduced well with specific surface area. The maximum configurational entropy increases with increasing porosity, and the entropy length of the pores decreases with increasing specific surface area and was used to calculate the average connectivity among the pores. The correlation among porosity, specific surface area, and permeability is consistent with the prediction from the Kozeny-Carman equation. From the relationship between the permeability and the Dcc of pores, the permeability can be expressed as a function of the Dcc of pores and porosity. The current methods and these newly identified correlations among structural parameters and properties provide improved insights into the nature of porous media and have useful geophysical and hydrological implications for elasticity and shear viscosity of complex composites of rock

Image Analysis and Estimation of Porosity and Permeability of Arnager Greensand, Upper Cretaceous, Denmark

DEFF Research Database (Denmark)

Solymar, Mikael; Fabricius, Ida

1999-01-01

Arnager Greensand consists of unconsolidated, poorly sorted fine-grained, glauconitic quartz sand, often silty or clayey, with a few horizons of cemented coarse-grained sand. Samples from the upper part of the Arnager Greensand were used for this study to estimate permeability from microscopic...... images. Backscattered Scanning Electron Microscope images from polished thin-sections were acquired for image analysis with the software PIPPIN(R). Differences in grey levels owing to density differences allowed us to estimate porosity, clay and particle content. The images were simplified into two...

Estimation of Fracture Porosity in an Unsaturated Fractured Welded Tuff Using Gas Tracer Testing

International Nuclear Information System (INIS)

B.M. Freifeild

2001-01-01

Kinematic fracture porosity is an important hydrologic transport parameter for predicting the potential of rapid contaminant migration through fractured rock. The transport velocity of a solute moving within a fracture network is inversely related to the fracture porosity. Since fracture porosity is often one or two orders of magnitude smaller than matrix porosity, and fracture permeability is often orders of magnitude greater than matrix permeability, solutes may travel significantly faster in the fracture network than in the surrounding matrix. This dissertation introduces a new methodology for conducting gas tracer tests using a field portable mass spectrometer along with analytical tools for estimating fracture porosity using the measured tracer concentration breakthrough curves. Field experiments were conducted at Yucca Mountain, Nevada, consisting of air-permeability transient testing and gas-tracer-transport tests. The experiments were conducted from boreholes drilled within an underground tunnel as part of an investigation of rock mass hydrological behavior. Air-permeability pressure transients, recorded during constant mass flux injections, have been analyzed using a numerical inversion procedure to identify fracture permeability and porosity. Dipole gas tracer tests have also been conducted from the same boreholes used for air-permeability testing. Mass breakthrough data has been analyzed using a random walk particle-tracking model, with a dispersivity that is a function of the advective velocity. The estimated fracture porosity using the tracer test and air-injection test data ranges from .001 to .015. These values are an order of magnitude greater than the values estimated by others using hydraulically estimated fracture apertures. The estimates of porosity made using air-permeability test data are shown to be highly sensitive to formation heterogeneity. Uncertainty analyses performed on the gas tracer test results show high confidence in the parameter

Estimation of Fracture Porosity in an Unsaturated Fractured Welded Tuff Using Gas Tracer Testing

Energy Technology Data Exchange (ETDEWEB)

B.M. Freifeild

2001-10-18

Kinematic fracture porosity is an important hydrologic transport parameter for predicting the potential of rapid contaminant migration through fractured rock. The transport velocity of a solute moving within a fracture network is inversely related to the fracture porosity. Since fracture porosity is often one or two orders of magnitude smaller than matrix porosity, and fracture permeability is often orders of magnitude greater than matrix permeability, solutes may travel significantly faster in the fracture network than in the surrounding matrix. This dissertation introduces a new methodology for conducting gas tracer tests using a field portable mass spectrometer along with analytical tools for estimating fracture porosity using the measured tracer concentration breakthrough curves. Field experiments were conducted at Yucca Mountain, Nevada, consisting of air-permeability transient testing and gas-tracer-transport tests. The experiments were conducted from boreholes drilled within an underground tunnel as part of an investigation of rock mass hydrological behavior. Air-permeability pressure transients, recorded during constant mass flux injections, have been analyzed using a numerical inversion procedure to identify fracture permeability and porosity. Dipole gas tracer tests have also been conducted from the same boreholes used for air-permeability testing. Mass breakthrough data has been analyzed using a random walk particle-tracking model, with a dispersivity that is a function of the advective velocity. The estimated fracture porosity using the tracer test and air-injection test data ranges from .001 to .015. These values are an order of magnitude greater than the values estimated by others using hydraulically estimated fracture apertures. The estimates of porosity made using air-permeability test data are shown to be highly sensitive to formation heterogeneity. Uncertainty analyses performed on the gas tracer test results show high confidence in the parameter

Estimation of fracture porosity in an unsaturated fractured welded tuff using gas tracer testing

Energy Technology Data Exchange (ETDEWEB)

Freifeld, Barry Mark [Univ. of California, Berkeley, CA (United States)

2001-12-01

Kinematic fracture porosity is an important hydrologic transport parameter for predicting the potential of rapid contaminant migration through fractured rock. The transport velocity of a solute moving within a fracture network is inversely related to the fracture porosity. Since fracture porosity is often one or two orders of magnitude smaller than matrix porosity, and fracture permeability is often orders of magnitude greater than matrix permeability, solutes may travel significantly faster in the fracture network than in the surrounding matrix. This dissertation introduces a new methodology for conducting gas tracer tests using a field portable mass spectrometer along with analytical tools for estimating fracture porosity using the measured tracer concentration breakthrough curves. Field experiments were conducted at Yucca Mountain, Nevada, consisting of air-permeability transient testing and gas-tracer-transport tests. The experiments were conducted from boreholes drilled within an underground tunnel as part of an investigation of rock mass hydrological behavior. Air-permeability pressure transients, recorded during constant mass flux injections, have been analyzed using a numerical inversion procedure to identify fracture permeability and porosity. Dipole gas tracer tests have also been conducted from the same boreholes used for air-permeability testing. Mass breakthrough data has been analyzed using a random walk particle-tracking model, with a dispersivity that is a function of the advective velocity. The estimated fracture porosity using the tracer test and air-injection test data ranges from .001 to .015. These values are an order of magnitude greater than the values estimated by others using hydraulically estimated fracture apertures. The estimates of porosity made using air-permeability test data are shown to be highly sensitive to formation heterogeneity. Uncertainty analyses performed on the gas tracer test results show high confidence in the parameter

Clogging in permeable concrete: A review.

Science.gov (United States)

Kia, Alalea; Wong, Hong S; Cheeseman, Christopher R

2017-05-15

Permeable concrete (or "pervious concrete" in North America) is used to reduce local flooding in urban areas and is an important sustainable urban drainage system. However, permeable concrete exhibits reduction in permeability due to clogging by particulates, which severely limits service life. This paper reviews the clogging mechanism and current mitigating strategies in order to inform future research needs. The pore structure of permeable concrete and characteristics of flowing particulates influence clogging, which occurs when particles build-up and block connected porosity. Permeable concrete requires regular maintenance by vacuum sweeping and pressure washing, but the effectiveness and viability of these methods is questionable. The potential for clogging is related to the tortuosity of the connected porosity, with greater tortuosity resulting in increased potential for clogging. Research is required to develop permeable concrete that can be poured on-site, which produces a pore structure with significantly reduced tortuosity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Quantifying porosity, compressibility and permeability in Shale

DEFF Research Database (Denmark)

Mbia, Ernest Ncha; Fabricius, Ida Lykke; Frykman, Peter

strain data. We found that Kozeny's modelled permeability fall in the same order of magnitude with measured permeability for shale rich in kaolinite but overestimates permeability by two to three orders of magnitudes for shale with high content of smectite. The empirical Yang and Aplin model gives good...... permeability estimate comparable to the measured one for shale rich in smectite. This is probably because Yang and Aplin model was calibrated in London clay which is rich in smectite....

Integration of ANFIS, NN and GA to determine core porosity and permeability from conventional well log data

Science.gov (United States)

Ja'fari, Ahmad; Hamidzadeh Moghadam, Rasoul

2012-10-01

Routine core analysis provides useful information for petrophysical study of the hydrocarbon reservoirs. Effective porosity and fluid conductivity (permeability) could be obtained from core analysis in laboratory. Coring hydrocarbon bearing intervals and analysis of obtained cores in laboratory is expensive and time consuming. In this study an improved method to make a quantitative correlation between porosity and permeability obtained from core and conventional well log data by integration of different artificial intelligent systems is proposed. The proposed method combines the results of adaptive neuro-fuzzy inference system (ANFIS) and neural network (NN) algorithms for overall estimation of core data from conventional well log data. These methods multiply the output of each algorithm with a weight factor. Simple averaging and weighted averaging were used for determining the weight factors. In the weighted averaging method the genetic algorithm (GA) is used to determine the weight factors. The overall algorithm was applied in one of SW Iran’s oil fields with two cored wells. One-third of all data were used as the test dataset and the rest of them were used for training the networks. Results show that the output of the GA averaging method provided the best mean square error and also the best correlation coefficient with real core data.

Integration of ANFIS, NN and GA to determine core porosity and permeability from conventional well log data

International Nuclear Information System (INIS)

Ja’fari, Ahmad; Moghadam, Rasoul Hamidzadeh

2012-01-01

Routine core analysis provides useful information for petrophysical study of the hydrocarbon reservoirs. Effective porosity and fluid conductivity (permeability) could be obtained from core analysis in laboratory. Coring hydrocarbon bearing intervals and analysis of obtained cores in laboratory is expensive and time consuming. In this study an improved method to make a quantitative correlation between porosity and permeability obtained from core and conventional well log data by integration of different artificial intelligent systems is proposed. The proposed method combines the results of adaptive neuro-fuzzy inference system (ANFIS) and neural network (NN) algorithms for overall estimation of core data from conventional well log data. These methods multiply the output of each algorithm with a weight factor. Simple averaging and weighted averaging were used for determining the weight factors. In the weighted averaging method the genetic algorithm (GA) is used to determine the weight factors. The overall algorithm was applied in one of SW Iran’s oil fields with two cored wells. One-third of all data were used as the test dataset and the rest of them were used for training the networks. Results show that the output of the GA averaging method provided the best mean square error and also the best correlation coefficient with real core data. (paper)

Hydrothermal alteration and permeability changes in granitic intrusions related to Sn-W deposits : case study of Panasqueira (Portugal)

Science.gov (United States)

Launay, Gaetan; Sizaret, Stanislas; Guillou-Frottier, Laurent; Gloaguen, Eric; Melleton, Jérémie; Pichavant, Michel; Champallier, Rémi; Pinto, Filipe

2017-04-01

The Panasqueira Sn-W deposit occurs as a dense network of flat wolframite and cassiterite-bearing quartz veins concentrated in the vicinity of a hidden greisen cupola, and to a lesser extent as disseminated cassiterites in the greisen. Previous studies (Thadeu 1951; 1979) have suggested that the Panasqueira deposit is genetically related to magmatic activity for which the most part is unexposed, and being only represented by the greisen cupola. Hydrothermal fluid circulation during the final stages of granite crystallisation has probably led to the greisenisation of the cupola followed by the deposition of the mineralization in the veins system. Mineral replacement reactions that occurred during the greisenisation could affect rock properties (porosity, density and permeability) which control fluid circulation in the granite. This study aims to investigate effects of greisenisation reactions on the dynamic (time varying) permeability that ultimately leads to fluid circulation in the greisen cupola. To do so, petrological study and experimental determinations of hydrodynamic features (porosity and permeability) for different granite alteration levels and petrographic types (unaltered granite to greisen) are combined and then integrated in coupled numerical models of fluid circulation around the granitic intrusion. Greisen occurs in the apical part of the granitic body and results in the pervasive alteration of the granite along the granite-schist contact. This greisen consists mainly of quartz and muscovite formed by the replacement of feldspars and bleaching of biotites of the initial granite. Otherwise, greisen is generally vuggy which suggests a porosity increase of the granite during hydrothermal alteration processes. This porosity increase has a positive effect on the permeability of the granitic system. Indeed, experimental measurements of permeability with the Paterson press indicate that the initial granite is impermeable (10-20 m2) whereas the greisen is

Well Test Analysis of Naturally Fractured Vuggy Reservoirs with an Analytical Triple Porosity – Double Permeability Model and a Global Optimization Method

Directory of Open Access Journals (Sweden)

Gómez Susana

2014-07-01

Full Text Available The aim of this work is to study the automatic characterization of Naturally Fractured Vuggy Reservoirs via well test analysis, using a triple porosity-dual permeability model. The inter-porosity flow parameters, the storativity ratios, as well as the permeability ratio, the wellbore storage effect, the skin and the total permeability will be identified as parameters of the model. In this work, we will perform the well test interpretation in Laplace space, using numerical algorithms to transfer the discrete real data given in fully dimensional time to Laplace space. The well test interpretation problem in Laplace space has been posed as a nonlinear least squares optimization problem with box constraints and a linear inequality constraint, which is usually solved using local Newton type methods with a trust region. However, local methods as the one used in our work called TRON or the well-known Levenberg-Marquardt method, are often not able to find an optimal solution with a good fit of the data. Also well test analysis with the triple porosity-double permeability model, like most inverse problems, can yield multiple solutions with good match to the data. To deal with these specific characteristics, we will use a global optimization algorithm called the Tunneling Method (TM. In the design of the algorithm, we take into account issues of the problem like the fact that the parameter estimation has to be done with high precision, the presence of noise in the measurements and the need to solve the problem computationally fast. We demonstrate that the use of the TM in this study, showed to be an efficient and robust alternative to solve the well test characterization, as several optimal solutions, with very good match to the data were obtained.

The permeability of concrete for reactor containment vessels

International Nuclear Information System (INIS)

Mills, R.H.

1983-07-01

Review of the literature pertaining to water, water vapour and gas transmission through concrete revealed conflicting views on the mechanisms involved and the influence of mix design parameters such as initial porosities and water/cement ratio. Consideration of the effects of ageing and of construction defects in field concrete were totally neglected in published work. Permeability data from three published papers were compared with permeability calculated according to Powers. The ratio of calculated to observed permeability varied from 40 x 10 -3 to 860 x 10 -3 for one group: from 0.17 x 10 3 to 8.6 x 10 3 in the second; and from 24 x 10 3 to 142 x 10 3 for the third. There were therefore wide discrepancies within each group of data and between groups. A bibliography was prepared and an exploratory experimental programme was mounted to determine the relative importance of key parameters such as cement type, porosity and water/cement ratio. Contrary to frequently cited references it was found that permeability of concrete was not significantly influenced by water/cement ratio when the starting porosity was constant. If water/cement ratio was held constant, however, the permeability was strongly influenced by starting porosity. It was also found that with constant water/cement ratio permeability increased with cement content. The value of fly ash and blast furnace slag in partial substitution for Portland cement is neglected in the literature but it is important since such substitutions alleviate alkali-silicate reactions. Permeability of concrete was significantly decreased by partial substitution of Portland cement with fly ash but there was no benefit in the use of blast furnace slag

Relative Permeability of Fractured Rock

Energy Technology Data Exchange (ETDEWEB)

Mark D. Habana

2002-06-30

Contemporary understanding of multiphase flow through fractures is limited. Different studies using synthetic fractures and various fluids have yielded different relative permeability-saturation relations. This study aimed to extend the understanding of multiphase flow by conducting nitrogen-water relative permeability experiments on a naturally-fractured rock from The Geysers geothermal field. The steady-state approach was used. However, steady state was achieved only at the endpoint saturations. Several difficulties were encountered that are attributed to phase interference and changes in fracture aperture and surface roughness, along with fracture propagation/initiation. Absolute permeabilities were determined using nitrogen and water. The permeability values obtained change with the number of load cycles. Determining the absolute permeability of a core is especially important in a fractured rock. The rock may change as asperities are destroyed and fractures propagate or st rain harden as the net stresses vary. Pressure spikes occurred in water a solute permeability experiments. Conceptual models of an elastic fracture network can explain the pressure spike behavior. At the endpoint saturations the water relative permeabilities obtained are much less than the nitrogen gas relative permeabilities. Saturations were determined by weighing and by resistivity calculations. The resistivity-saturation relationship developed for the core gave saturation values that differ by 5% from the value determined by weighing. Further work is required to complete the relative permeability curve. The steady-state experimental approach encountered difficulties due to phase interference and fracture change. Steady state may not be reached until an impractical length of time. Thus, unsteady-state methods should be pursued. In unsteady-state experiments the challenge will be in quantifying rock fracture change in addition to fluid flow changes.

Effects of ancient porosity and permeability on formation of sedimentary dolomites: Devonian Jefferson Formation (Frasnian), south-central Montana

Energy Technology Data Exchange (ETDEWEB)

Smith, T.M.; Dorobek, S.L.

1987-08-01

Petrographic and geochemical evidence indicates that multiple dolomitization and dolomite stabilization events affected the Devonian Jefferson Formation (Frasnian) in south-central Montana. Several types of dolomite occur, defined by cathodoluminescence: nonzoned, dully luminescent subhedral-anhedral mosaics (most common), euhedral nonzoned and zoned dolomites, zoned dolomite cements, and irregularly luminescent dolomites (dully luminescent with irregularly luminescent regions). The irregularly luminescent fabrics probably represent partial replacement of early dolomite phases with later dolomite phases. Nonzoned, Ca-enriched, euhedral dolomites occur in calcite-cemented, coarse-grained limestone layers. These permeable layers probably were conduits for early meteoric waters, that occluded porosity in the limestones and prevented later dolomite stabilization. Irregularly luminescent dolomites are interpreted as intermediate fabrics in the dolomite stabilization process. Later calcite cements which occlude intercrystalline porosity prevented further dolomite replacement. Total recrystallization of remaining dolomites and formation of final dully luminescent mosaics occurred prior to brecciation and stylolitization.

A fractal analytical model for the permeabilities of fibrous gas diffusion layer in proton exchange membrane fuel cells

International Nuclear Information System (INIS)

Xiao, Boqi; Fan, Jintu; Ding, Feng

2014-01-01

The study of water and gas transport through fibrous gas diffusion layer (GDL) is important to the optimization of proton exchange membrane fuel cells (PEMFCs). In this work, analytical models of dimensionless permeability, and water and gas relative permeabilities of fibrous GDL in PEMFCs are derived using fractal theory. In our models, the structure of fibrous GDL is characterized in terms of porosity, tortuosity fractal dimension (D T ), pore area fractal dimensions (d f ), water phase (d f,w ) and gas phase (d f,g ) fractal dimensions. The predicted dimensionless permeability, water and gas relative permeabilities based on the proposed models are in good agreement with experimental data and predictions of numerical simulations reported in the literature. The model reveals that, although water phase and gas phase fractal dimensions strongly depend on porosity, the water and gas relative permeabilities are independent of porosity and are a function of water saturation only. It is also shown that the dimensionless permeability decreases significantly with the increase of tortuosity fractal dimension. On the other hand, there is only a small decrease in the water and gas relative permeabilities when tortuosity fractal dimension increases. One advantage of the proposed analytical model is that it contains no empirical constant, which is normally required in past models

The Multi-Porosity Multi-Permeability and Electrokinetic Natures of Shales and Their Effects in Hydraulic Fracturing of Unconventional Shale Reservoirs

Science.gov (United States)

Liu, C.; Hoang, S. K.; Tran, M. H.; Abousleiman, Y. N.

2013-12-01

Imaging studies of unconventional shale reservoir rocks have recently revealed the multi-porosity multi-permeability nature of these intricate formations. In particular, the porosity spectrum of shale reservoir rocks often comprises of the nano-porosity in the organic matters, the inter-particle micro-porosity, and the macroscopic porosity of the natural fracture network. Shale is also well-known for its chemically active behaviors, especially shrinking and swelling when exposed to aqueous solutions, as the results of pore fluid exchange with external environment due to the difference in electro-chemical potentials. In this work, the effects of natural fractures and electrokinetic nature of shale on the formation responses during hydraulic fracturing are examined using the dual-poro-chemo-electro-elasticity approach which is a generalization of the classical Biot's poroelastic formulation. The analyses show that the presence of natural fractures can substantially increase the leak-off rate of fracturing fluid into the formation and create a larger region of high pore pressure near the fracture face as shown in Fig.1a. Due to the additional fluid invasion, the naturally fractured shale swells up more and the fracture aperture closes faster compared to an intrinsically low permeability non-fractured shale formation as shown in Fig.1b. Since naturally fractured zones are commonly targeted as pay zones, it is important to account for the faster fracture closing rate in fractured shales in hydraulic fracturing design. Our results also show that the presence of negative fixed charges on the surface of clay minerals creates an osmotic pressure at the interface of the shale and the external fluid as shown in Fig.1c. This additional Donnan-induced pore pressure can result in significant tensile effective stresses and tensile damage in the shale as shown in Fig.1d. The induced tensile damage can exacerbate the problem of proppant embedment resulting in more fracture closure

Computer model for determining fracture porosity and permeability in the Conasauga Group, Oak Ridge National Laboratory, Tennessee

International Nuclear Information System (INIS)

Sledz, J.J.; Huff, D.D.

1981-04-01

Joint orientations for the shale and siltstone beds of the Conasauga Group were measured from outcrop exposures on the Oak Ridge National Laboratory Reservation. The data collected from two strike belts (structural trends) were analyzed with the use of the computer and subdivided into individual joint sets. The joint set patterns in the Northern outcrop belt were too complex for orientation prediction; joint formation is believed to be influenced by polyphase deformation. The Southern Conasauga Belt contains an orthogonal joint set consisting of strike and a-c joints in all outcrops measured. These are believed to be tension joints formed during thrust sheet emplacement. Joint length and spacing, measured in the field, were found to be extremely variable within each exposure and highly dependent upon surficial weathering. The measurements from all locations were combined for detailed analysis and trend prediction. Results showed that the joint length and spacing increased with increasing bed thickness in the siltstone, while the bed thickness variations in the shale had little effect on the joints. A computer model was developed by combining the joint orientation, joint spacing, and joint length data collected in the field with subsurface drill core information for the purpose of calculating the fracture porosity and permeability of the rocks. The joint gap width was measured from both outcrop and subsurface samples with ranges from 0.1 mm to 0.7 mm in the siltstones and less than 0.2 mm in the shales. The value for the joint gap width was found to be the major factor in the fracture porosity and permeability calculation

Porosity Prediction of Plain Weft Knitted Fabrics

Directory of Open Access Journals (Sweden)

Muhammad Owais Raza Siddiqui

2014-12-01

Full Text Available Wearing comfort of clothing is dependent on air permeability, moisture absorbency and wicking properties of fabric, which are related to the porosity of fabric. In this work, a plug-in is developed using Python script and incorporated in Abaqus/CAE for the prediction of porosity of plain weft knitted fabrics. The Plug-in is able to automatically generate 3D solid and multifilament weft knitted fabric models and accurately determine the porosity of fabrics in two steps. In this work, plain weft knitted fabrics made of monofilament, multifilament and spun yarn made of staple fibers were used to evaluate the effectiveness of the developed plug-in. In the case of staple fiber yarn, intra yarn porosity was considered in the calculation of porosity. The first step is to develop a 3D geometrical model of plain weft knitted fabric and the second step is to calculate the porosity of the fabric by using the geometrical parameter of 3D weft knitted fabric model generated in step one. The predicted porosity of plain weft knitted fabric is extracted in the second step and is displayed in the message area. The predicted results obtained from the plug-in have been compared with the experimental results obtained from previously developed models; they agreed well.

Permeability During Magma Expansion and Compaction

Science.gov (United States)

Gonnermann, Helge. M.; Giachetti, Thomas; Fliedner, Céline; Nguyen, Chinh T.; Houghton, Bruce F.; Crozier, Joshua A.; Carey, Rebecca J.

2017-12-01

Plinian lapilli from the 1060 Common Era Glass Mountain rhyolitic eruption of Medicine Lake Volcano, California, were collected and analyzed for vesicularity and permeability. A subset of the samples were deformed at a temperature of 975°, under shear and normal stress, and postdeformation porosities and permeabilities were measured. Almost all undeformed samples fall within a narrow range of vesicularity (0.7-0.9), encompassing permeabilities between approximately 10-15 m2 and 10-10 m2. A percolation threshold of approximately 0.7 is required to fit the data by a power law, whereas a percolation threshold of approximately 0.5 is estimated by fitting connected and total vesicularity using percolation modeling. The Glass Mountain samples completely overlap with a range of explosively erupted silicic samples, and it remains unclear whether the erupting magmas became permeable at porosities of approximately 0.7 or at lower values. Sample deformation resulted in compaction and vesicle connectivity either increased or decreased. At small strains permeability of some samples increased, but at higher strains permeability decreased. Samples remain permeable down to vesicularities of less than 0.2, consistent with a potential hysteresis in permeability-porosity between expansion (vesiculation) and compaction (outgassing). We attribute this to retention of vesicle interconnectivity, albeit at reduced vesicle size, as well as bubble coalescence during shear deformation. We provide an equation that approximates the change in permeability during compaction. Based on a comparison with data from effusively erupted silicic samples, we propose that this equation can be used to model the change in permeability during compaction of effusively erupting magmas.

Impact of Three-Phase Relative Permeability and Hysteresis Models on Forecasts of Storage Associated With CO2-EOR

Science.gov (United States)

Jia, Wei; McPherson, Brian; Pan, Feng; Dai, Zhenxue; Moodie, Nathan; Xiao, Ting

2018-02-01

Geological CO2 sequestration in conjunction with enhanced oil recovery (CO2-EOR) includes complex multiphase flow processes compared to CO2 storage in deep saline aquifers. Two of the most important factors affecting multiphase flow in CO2-EOR are three-phase relative permeability and associated hysteresis, both of which are difficult to measure and are usually represented by numerical interpolation models. The purpose of this study is to improve understanding of (1) the relative impacts of different three-phase relative permeability models and hysteresis models on CO2 trapping mechanisms, and (2) uncertainty associated with these two factors. Four different three-phase relative permeability models and three hysteresis models were applied to simulations of an active CO2-EOR site, the SACROC unit located in western Texas. To eliminate possible bias of deterministic parameters, we utilized a sequential Gaussian simulation technique to generate 50 realizations to describe heterogeneity of porosity and permeability, based on data obtained from well logs and seismic survey. Simulation results of forecasted CO2 storage suggested that (1) the choice of three-phase relative permeability model and hysteresis model led to noticeable impacts on forecasted CO2 sequestration capacity; (2) impacts of three-phase relative permeability models and hysteresis models on CO2 trapping are small during the CO2-EOR injection period, and increase during the post-EOR CO2 injection period; (3) the specific choice of hysteresis model is more important relative to the choice of three-phase relative permeability model; and (4) using the recommended three-phase WAG (Water-Alternating-Gas) hysteresis model may increase the impact of three-phase relative permeability models and uncertainty due to heterogeneity.

An Evaluation of Subsurface Microbial Activity Conditional to Subsurface Temperature, Porosity, and Permeability at North American Carbon Sequestration Sites

Energy Technology Data Exchange (ETDEWEB)

Wilson, B. [Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); National Energy Technology Lab. (NETL), Albany, OR (United States); Mordensky, S. [Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); National Energy Technology Lab. (NETL), Albany, OR (United States); Verba, Circe [National Energy Technology Lab. (NETL), Albany, OR (United States); Rabjohns, K. [Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); National Energy Technology Lab. (NETL), Albany, OR (United States); Colwell, F. [National Energy Technology Lab. (NETL), Albany, OR (United States); Oregon State Univ., Corvallis, OR (United States). College of Earth, Ocean, and Atmospheric Sciences

2016-06-21

Several nations, including the United States, recognize global climate change as a force transforming the global ecosphere. Carbon dioxide (CO₂) is a greenhouse gas that contributes to the evolving climate. Reduction of atmospheric CO₂ levels is a goal for many nations and carbon sequestration which traps CO₂ in the Earth’s subsurface is one method to reduce atmospheric CO₂ levels. Among the variables that must be considered in developing this technology to a national scale is microbial activity. Microbial activity or biomass can change rock permeability, alter artificial seals around boreholes, and play a key role in biogeochemistry and accordingly may determine how CO₂ is sequestered underground. Certain physical parameters of a reservoir found in literature (e.g., temperature, porosity, and permeability) may indicate whether a reservoir can host microbial communities. In order to estimate which subsurface formations may host microbes, this report examines the subsurface temperature, porosity, and permeability of underground rock formations that have high potential to be targeted for CO₂ sequestration. Of the 268 North American wellbore locations from the National Carbon Sequestration Database (NATCARB; National Energy and Technology Laboratory, 2015) and 35 sites from Nelson and Kibler (2003), 96 sequestration sites contain temperature data. Of these 96 sites, 36 sites have temperatures that would be favorable for microbial survival, 48 sites have mixed conditions for supporting microbial populations, and 11 sites would appear to be unfavorable to support microbial populations. Future studies of microbe viability would benefit from a larger database with more formation parameters (e.g. mineralogy, structure, and groundwater chemistry), which would help to increase understanding of where CO₂ sequestration could be most efficiently implemented.

Permeability model of sintered porous media: analysis and experiments

Science.gov (United States)

Flórez Mera, Juan Pablo; Chiamulera, Maria E.; Mantelli, Marcia B. H.

2017-11-01

In this paper, the permeability of porous media fabricated from copper powder sintering process was modeled and measured, aiming the use of the porosity as input parameter for the prediction of the permeability of sintering porous media. An expression relating the powder particle mean diameter with the permeability was obtained, based on an elementary porous media cell, which is physically represented by a duct formed by the arrangement of spherical particles forming a simple or orthorhombic packing. A circular duct with variable section was used to model the fluid flow within the porous media, where the concept of the hydraulic diameter was applied. Thus, the porous is modeled as a converging-diverging duct. The electrical circuit analogy was employed to determine two hydraulic resistances of the cell: based on the Navier-Stokes equation and on the Darcýs law. The hydraulic resistances are compared between themselves and an expression to determine the permeability as function of average particle diameter is obtained. The atomized copper powder was sifted to reduce the size dispersion of the particles. The porosities and permeabilities of sintered media fabricated from powders with particle mean diameters ranging from 20 to 200 microns were measured, by means of the image analysis method and using an experimental apparatus. The permeability data of a porous media, made of copper powder and saturated with distilled water, was used to compare with the permeability model. Permeability literature models, which considers that powder particles have the same diameter and include porosity data as input parameter, were compared with the present model and experimental data. This comparison showed to be quite good.

Evaluating the Influence of Pore Architecture and Initial Saturation on Wettability and Relative Permeability in Heterogeneous, Shallow-Shelf Carbonates

Energy Technology Data Exchange (ETDEWEB)

Byrnes, Alan P.; Bhattacharya, Saibal; Victorine, John; Stalder, Ken

2007-09-30

Thin (3-40 ft thick), heterogeneous, limestone and dolomite reservoirs, deposited in shallow-shelf environments, represent a significant fraction of the reservoirs in the U.S. midcontinent and worldwide. In Kansas, reservoirs of the Arbuckle, Mississippian, and Lansing-Kansas City formations account for over 73% of the 6.3 BBO cumulative oil produced over the last century. For these reservoirs basic petrophysical properties (e.g., porosity, absolute permeability, capillary pressure, residual oil saturation to waterflood, resistivity, and relative permeability) vary significantly horizontally, vertically, and with scale of measurement. Many of these reservoirs produce from structures of less than 30-60 ft, and being located in the capillary pressure transition zone, exhibit vertically variable initial saturations and relative permeability properties. Rather than being simpler to model because of their small size, these reservoirs challenge characterization and simulation methodology and illustrate issues that are less apparent in larger reservoirs where transition zone effects are minor and most of the reservoir is at saturations near S{sub wirr}. These issues are further augmented by the presence of variable moldic porosity and possible intermediate to mixed wettability and the influence of these on capillary pressure and relative permeability. Understanding how capillary-pressure properties change with rock lithology and, in turn, within transition zones, and how relative permeability and residual oil saturation to waterflood change through the transition zone is critical to successful reservoir management and as advanced waterflood and improved and enhanced recovery methods are planned and implemented. Major aspects of the proposed study involve a series of tasks to measure data to reveal the nature of how wettability and drainage and imbibition oil-water relative permeability change with pore architecture and initial water saturation. Focus is placed on

Xenon NMR measurements of permeability and tortuosity in reservoir rocks.

Science.gov (United States)

Wang, Ruopeng; Pavlin, Tina; Rosen, Matthew Scott; Mair, Ross William; Cory, David G; Walsworth, Ronald Lee

2005-02-01

In this work we present measurements of permeability, effective porosity and tortuosity on a variety of rock samples using NMR/MRI of thermal and laser-polarized gas. Permeability and effective porosity are measured simultaneously using MRI to monitor the inflow of laser-polarized xenon into the rock core. Tortuosity is determined from measurements of the time-dependent diffusion coefficient using thermal xenon in sealed samples. The initial results from a limited number of rocks indicate inverse correlations between tortuosity and both effective porosity and permeability. Further studies to widen the number of types of rocks studied may eventually aid in explaining the poorly understood connection between permeability and tortuosity of rock cores.

An optimized microstructure to minimizing in-plane and through-plane pressure drops of fibrous materials: Counter-intuitive reduction of gas diffusion layer permeability with porosity

Science.gov (United States)

Sadeghifar, Hamidreza

2018-05-01

The present study experimentally investigates the realistic functionality of in-plane and through-plane pressure drops of layered fibrous media with porosity, fiber diameter, fiber spacing, fiber-fiber angles and fiber-flow angles. The study also reveals that pressure drop may increase with porosity and fiber diameter under specific circumstances. This counter-intuitive point narrows down the validity range of widely-used permeability-porosity-diameter models or correlations. It is found that, for fibrous materials, the most important parameter that impacts the in-plane pressure drop is not their porosities but the number of fibers extended in the flow direction. It is also concluded that in-plane pressure drop is highly dependent upon the flow direction (fiber-flow angles), especially at lower porosities. Contrary to in-plane pressure drop, through-plane pressure drop is a weak function of fiber-fiber angles but is strongly impacted by fiber spacing, especially at lower porosities. At a given porosity, low through-plane pressure drops occur if fiber spacing does not change practically from one layer to another. Through-plane pressure drop also, insignificantly, increases with the intersecting angles between fibers. An optimized microstructure of fibrous media resulting in minimal in-plane and through-plane pressure drops is also offered for the first time in this work.

Elementary analysis on the main factors affecting the permeability of sandstones

International Nuclear Information System (INIS)

Gong Binli

2006-01-01

Researches show that in the early stage of sandstone diagenesis, compaction, pressure solution, cementation and replacement reduce both the porosity and the permeability. The cementation of authigenic kaolinite may preserve the tiny intergranular pore-space, and slightly influence the porosity, and even increase the permeability. During the middle to late stage of diagenesis, the organic matter becomes matured, hydrocarbon and acidic water are produced, which forms secondary porosity by the dissolution and the corrosion, and greatly increases the permeability of sandstones and provides a favorable prerequisite for the formation of sandstone-type uranium deposits. The interlayered oxidation alteration, oil-gas reduction and low-temperature hydrothermal alteration also produce secondary porosity in epigenetic reforming stage, which finally decides the permeability after the formation of sandstone-type uranium deposits. This is an important condition for in-situ leaching of sandstone-type uranium deposit. (authors)

Permeability prediction in chalks

DEFF Research Database (Denmark)

Alam, Mohammad Monzurul; Fabricius, Ida Lykke; Prasad, Manika

2011-01-01

The velocity of elastic waves is the primary datum available for acquiring information about subsurface characteristics such as lithology and porosity. Cheap and quick (spatial coverage, ease of measurement) information of permeability can be achieved, if sonic velocity is used for permeability p...... significantly using the effective specific surface as the fluid-flow concept. The FZI unit is appropriate for highly permeable sedimentary rocks such as sandstones and limestones that have small surface areas....

High Resolution ground penetrating radar (GPR) measurements at the laboratory scale to model porosity and permeability in the Miami Limestone in South Florida.

Science.gov (United States)

Mount, G. J.; Comas, X.

2015-12-01

Subsurface water flow within the Biscayne aquifer is controlled by the heterogeneous distribution of porosity and permeability in the karst Miami Limestone and the presence of numerous dissolution and mega-porous features. The dissolution features and other high porosity areas can create preferential flow paths and direct recharge to the aquifer, which may not be accurately conceptualized in groundwater flow models. As hydrologic conditions are undergoing restoration in the Everglades, understanding the distribution of these high porosity areas within the subsurface would create a better understanding of subsurface flow. This research utilizes ground penetrating radar to estimate the spatial variability of porosity and dielectric permittivity of the Miami Limestone at centimeter scale resolution at the laboratory scale. High frequency GPR antennas were used to measure changes in electromagnetic wave velocity through limestone samples under varying volumetric water contents. The Complex Refractive Index Model (CRIM) was then applied in order to estimate porosity and dielectric permittivity of the solid phase of the limestone. Porosity estimates ranged from 45.2-66.0% from the CRIM model and correspond well with estimates of porosity from analytical and digital image techniques. Dielectric permittivity values of the limestone solid phase ranged from 7.0 and 13.0, which are similar to values in the literature. This research demonstrates the ability of GPR to identify the cm scale spatial variability of aquifer properties that influence subsurface water flow which could have implications for groundwater flow models in the Biscayne and potentially other shallow karst aquifers.

The effect of pore-scale geometry and wettability on two-phase relative permeabilities within elementary cells

Science.gov (United States)

Bianchi Janetti, Emanuela; Riva, Monica; Guadagnini, Alberto

2017-04-01

We study the relative role of the complex pore space geometry and wettability of the solid matrix on the quantification of relative permeabilities characterizing steady state immiscible two-phase flow in porous media. We do so by considering elementary cells, which are typically employed in upscaling frameworks based on, e.g., homogenization or volume averaging. In this context one typically relies on the solution of pore-scale physics at a scale which is much smaller than that of an investigated porous system. Pressure-driven two-phase flow following simultaneous co-current injection of water and oil is numerically solved for a suite of regular and stochastically generated two-dimensional explicit elementary cells with fixed porosity and sharing main topological/morphological features. We show that relative permeabilities of the randomly generated elementary cells are significantly influenced by the formation of preferential percolation paths (principal pathways), giving rise to a strongly nonuniform distribution of fluid fluxes. These pathways are a result of the spatially variable resistance that the random pore structures exert on the fluid. The overall effect on relative permeabilities of the diverse organization of principal pathways, as driven by a given random realization at the scale of the unit cell, is significantly larger than that of the wettability of the host rock. In contrast to what can be observed for the random cells analyzed, relative permeabilities of regular cells display a clear trend with contact angle at the investigated scale. Our findings suggest the need to perform systematic upscaling studies in a stochastic context, to propagate the effects of uncertain pore space geometries to a probabilistic description of relative permeability curves at the continuum scale.

Estimating the Permeability of Carbonate Rocks from the Fractal Properties of Moldic Pores using the Kozeny-Carman Equation

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Adewale Amosu

2018-02-01

Full Text Available Reservoir modeling of carbonate rocks requires a proper understanding of the pore space distribution and its relationship to permeability. Using a pigeonhole fractal model we characterize the fractal geometry of moldic pore spaces and extract the fractal dimension. We apply the Kozeny-Carman equation and equations relating the tortuosity and the porosity to the fractal dimension to derive an empirical relationship between permeability and porosity.

Is trabecular bone permeability governed by molecular ordering-induced fluid viscosity gain? Arguments from re-evaluation of experimental data in the framework of homogenization theory.

Science.gov (United States)

Abdalrahman, T; Scheiner, S; Hellmich, C

2015-01-21

It is generally agreed on that trabecular bone permeability, a physiologically important quantity, is governed by the material׳s (vascular or intertrabecular) porosity as well as by the viscosity of the pore-filling fluids. Still, there is less agreement on how these two key factors govern bone permeability. In order to shed more light onto this somewhat open issue, we here develop a random homogenization scheme for upscaling Poiseuille flow in the vascular porosity, up to Darcy-type permeability of the overall porous medium "trabecular bone". The underlying representative volume element of the macroscopic bone material contains two types of phases: a spherical, impermeable extracellular bone matrix phase interacts with interpenetrating cylindrical pore channel phases that are oriented in all different space directions. This type of interaction is modeled by means of a self-consistent homogenization scheme. While the permeability of the bone matrix equals to zero, the permeability of the pore phase is found through expressing the classical Hagen-Poiseuille law for laminar flow in the format of a "micro-Darcy law". The upscaling scheme contains pore size and porosity as geometrical input variables; however, they can be related to each other, based on well-known relations between porosity and specific bone surface. As two key results, validated through comprehensive experimental data, it appears (i) that the famous Kozeny-Carman constant (which relates bone permeability to the cube of the porosity, the square of the specific surface, as well as to the bone fluid viscosity) needs to be replaced by an again porosity-dependent rational function, and (ii) that the overall bone permeability is strongly affected by the pore fluid viscosity, which, in case of polarized fluids, is strongly increased due to the presence of electrically charged pore walls. Copyright © 2014 Elsevier Ltd. All rights reserved.

Porosity and permeability evolution of vesicular basalt reservoirs with increasing depth: constraints from the Big Island of Hawai'i

Science.gov (United States)

Millett, John; Haskins, Eric; Thomas, Donald; Jerram, Dougal; Planke, Sverre; Healy, Dave; Kück, Jochem; Rossetti, Lucas; Farrell, Natalie; Pierdominici, Simona

2017-04-01

Volcanic reservoirs are becoming increasingly important in the targeting of petroleum, geothermal and water resources globally. However, key areas of uncertainty in relation to volcanic reservoir properties during burial in different settings remain. In this contribution, we present results from borehole logging and sampling operations within two fully cored c. 1.5 km deep boreholes, PTA2 and KMA1, from the Humúula saddle region on the Big Island of Hawai'i. The boreholes were drilled as part of the Humu'ula Groundwater Research Project (HGRP) between 2013-2016 and provide unique insights into the evolution of pore structure with increasing burial in a basaltic dominated lava sequence. The boreholes encounter mixed sequences of 'a'ā, pāhoehoe and transitional lava flows along with subsidiary intrusions and sediments from the shield to post-shield phases of Mauna Kea. Borehole wireline data including sonic, spectral gamma and Televiewer imagery were collected along with density, porosity, permeability and ultrasonic velocity laboratory measurements from core samples. A range of intra-facies were sampled for analysis from various depths within the two boreholes. By comparison with core data, the potential for high resolution Televiewer imaging to reveal spectacular intra-facies features including individual vesicles, vesicle segregations, 'a'ā rubble zones, intrusive contacts, and intricate pāhoehoe lava flow lobe morphologies is demonstrated. High quality core data enables the calibration of Televiewer facies enabling improved interpretation of volcanic reservoir features in the more common exploration scenario where core is absent. Laboratory results record the ability of natural vesicular basalt samples to host very high porosity (>50%) and permeability (>10 darcies) within lava flow top facies which we demonstrate are associated with vesicle coalescence and not micro-fractures. These properties may be maintained to depths of c. 1.5 km in regions of limited

Effective stress law for the permeability and deformation of four porous limestones

Science.gov (United States)

Wang, Y.; Meng, F.; Wang, X.; Baud, P.; Wong, T. F.

2017-12-01

The effective stress behavior of a rock is related to the geometric of its pore space. In a microscopically homogeneous assemblage, effective stress coefficients for permeability, volumetric strain and porosity change are predicted to be equal to or less than unity. Experimental measurements are in basic agreement with this prediction, with exceptions particularly in clay-rich sandstones, for which effective stress coefficient for permeability up to 7 was documented. Little is known about carbonates, but Ghabezloo et al. [2009] studied the permeability of an oolitic limestone (from Nimes, France) with 17% porosity and reported effective stress coefficients up to 2.4. We investigated this phenomenon in Indiana, Leitha, Purbeck, and Thala limestones with porosities of 13-30%. Measurements were made at room temperature on water-saturated samples at confining and pore pressures of 7-15 MPa and 1-3 MPa, respectively. Unlike previous studies limited to the permeability, we also determined the effective stress coefficients for volumetric strain and porosity change. Indiana limestone is oolitic, and not surprisingly its behaviour was similar to Nimes limestone, with an effective stress coefficient for permeability of 2.5. Our Indiana limestone data showed that whereas the effective stress coefficient for volumetric strain was 1. Measurements on Purbeck and Thala limestones are consistent with these inequalities, with effective stress coefficients for permeability and porosity change >1 and that for volumetric strain <1. Even though Purbeck and Thala limestones are micritic with appreciable amount of quartz and dolomite, microstructural and mercury porosimetry data showed that their pore spaces are similar to the oolitic limestones, in that the pore size distribution is bimodal with significant fractions of both macropores and micropores. Berryman [1992] analyzed theoretically a rock made up of two porous constituents. Our new data are in agreement with inequalities he

Diagenetic effect on permeabilities of geothermal sandstone reservoirs

DEFF Research Database (Denmark)

Weibel, Rikke; Olivarius, Mette; Kristensen, Lars

The Danish subsurface contains abundant sedimentary deposits, which can be utilized for geothermal heating. The Upper Triassic – Lower Jurassic continental-marine sandstones of the Gassum Formation has been utilised as a geothermal reservoir for the Thisted Geothermal Plant since 1984 extracting...... and permeability is caused by increased diagenetic changes of the sandstones due to increased burial depth and temperatures. Therefore, the highest water temperatures typically correspond with the lowest porosities and permeabilities. Especially the permeability is crucial for the performance of the geothermal......-line fractures. Continuous thin chlorite coatings results in less porosity- and permeability-reduction with burial than the general reduction with burial, unless carbonate cemented. Therefore, localities of sandstones characterized by these continuous chlorite coatings may represent fine geothermal reservoirs...

Linking air and water transport in intact soils to macro-porosity by combining laboratory measurements and X-ray Computed Tomography

DEFF Research Database (Denmark)

Katuwal, Sheela; Norgaard, Trine; Møldrup, Per

-porosity (R2 = 0.80 for air permeability: R2= 0.61 for 5% arrival time) and macro-porosity of the restricting layer (R2=0.83 for air permeability: R2= 0.71 for 5% arrival time) over air-filled porosity and all the correlations were positive. The high positive correlation these air and water transport...... functions with macro-porosity stressed the importance of continuity and tortuosity of pores in air, water and solute flow and transport through the soils. Negative correlations of air permeability, 5% arrival time of tracer and macro-porosity were obtained with bulk density whereas with other soil physical......With an objective to link the hydraulic properties of soil with the soil structural properties, air permeability and 5% arrival time of a conservative tracer was measured for large undisturbed soil columns from the same agricultural field. The same soil columns were scanned with a medical scanner...

Double porosity models for the description of water infiltration in wood

DEFF Research Database (Denmark)

Krabbenhøft, Kristian; Damkilde, Lars

2004-01-01

In this paper some of the possibilities of applying double porosity and permeability models to the problem of water infiltration in wood are explored. It is shown that the double porosity model can capture a number of commonly reported anomalies including two-stage infiltration...

Porosity, single-phase permeability, and capillary pressure data from preliminary laboratory experiments on selected samples from Marker Bed 139 at the Waste Isolation Pilot Plant. Volume 1 of 3: Main report, appendix A

Energy Technology Data Exchange (ETDEWEB)

Howarth, S.M.; Christian-Frear, T.

1997-08-01

Three groups of core samples from Marker Bed 139 of the Salado Formation at the Waste Isolation Pilot Plant (WIPP) were analyzed to provide data to support the development of numerical models used to predict the long-term hydrologic and structural response of the WIPP repository. These laboratory experiments, part of the FY93 Experimental Scoping Activities of the Salado Two-Phase Flow Laboratory Program, were designed to (1) generate WIPP-specific porosity and single-phase permeability data, (2) provide information needed to design and implement planned tests to measure two-phase flow properties, including threshold pressure, capillary pressure, and relative permeability, and (3) evaluate the suitability of using analog correlations for the Salado Formation to assess the long-term performance of the WIPP. This report contains a description of the boreholes core samples, the core preparation techniques used, sample sizes, testing procedures, test conditions, and results of porosity and single-phase permeability tests performed at three laboratories: TerraTek, Inc. (Salt Lake City, UT), RE/SPEC, Inc. (Rapid City, SD), and Core Laboratories-Special Core Analysis Laboratory (Carrollton, TX) for Rock Physics Associates. In addition, this report contains the only WIPP-specific two-phase-flow capillary-pressure data for twelve core samples. The WIPP-specific data generated in this laboratory study and in WIPP field-test programs and information from suitable analogs will form the basis for specification of single- and two-phase flow parameters for anhydrite markers beds for WIPP performance assessment calculations.

Porosity, single-phase permeability, and capillary pressure data from preliminary laboratory experiments on selected samples from Marker Bed 139 at the Waste Isolation Pilot Plant. Volume 1 of 3: Main report, appendix A

International Nuclear Information System (INIS)

Howarth, S.M.; Christian-Frear, T.

1997-08-01

Three groups of core samples from Marker Bed 139 of the Salado Formation at the Waste Isolation Pilot Plant (WIPP) were analyzed to provide data to support the development of numerical models used to predict the long-term hydrologic and structural response of the WIPP repository. These laboratory experiments, part of the FY93 Experimental Scoping Activities of the Salado Two-Phase Flow Laboratory Program, were designed to (1) generate WIPP-specific porosity and single-phase permeability data, (2) provide information needed to design and implement planned tests to measure two-phase flow properties, including threshold pressure, capillary pressure, and relative permeability, and (3) evaluate the suitability of using analog correlations for the Salado Formation to assess the long-term performance of the WIPP. This report contains a description of the boreholes core samples, the core preparation techniques used, sample sizes, testing procedures, test conditions, and results of porosity and single-phase permeability tests performed at three laboratories: TerraTek, Inc. (Salt Lake City, UT), RE/SPEC, Inc. (Rapid City, SD), and Core Laboratories-Special Core Analysis Laboratory (Carrollton, TX) for Rock Physics Associates. In addition, this report contains the only WIPP-specific two-phase-flow capillary-pressure data for twelve core samples. The WIPP-specific data generated in this laboratory study and in WIPP field-test programs and information from suitable analogs will form the basis for specification of single- and two-phase flow parameters for anhydrite markers beds for WIPP performance assessment calculations

A theoretical model for gas permeability in a composite membrane

International Nuclear Information System (INIS)

Serrano, D. A

2009-01-01

We present in this work an analytical expression for permeability in a two-layer composite membrane, which was derived assuming the same hypothesis as those of Adzumi model for permeability in a homogeneous membrane. Whereas in Adzumi model permeability shows a linear dependence on the mean pressure, our model for a composite membrane related permeability to pressure through a rather complex expression, which covers the whole range of flow, from molecular-Knudsen to viscous-Poiseuille regimes. The expression obtained for permeability contained information of membrane structural properties as pore size, porosity and thickness of each layer, as well as gas nature and operational conditions. Our two-layer-model expression turns into Adzumi formula when the structure of the layers approach to each other. [es

Analytic Model for Predicting the Permeability of Foam-type Wick

Energy Technology Data Exchange (ETDEWEB)

Ngo, Ich-Long; Byon, Chan [Yeungnam Univ., Gyeongsan (Korea, Republic of)

2016-06-15

Wicks play an important role in determining the thermal performance of heat pipes. Foam-type wicks are known to have good potential for enhancing the capillary performance of conventional types of wicks, and this is because of their high porosity and permeability. In this study, we develop an analytic expression for predicting the permeability of a foam-type wick based on extensive numerical work. The proposed correlation is based on the modified Kozeny-Carman’s equation, where the Kozeny-Carman coefficient is given as an exponential function of porosity. The proposed correlations are shown to predict the previous experimental results well for an extensive parametric range. The permeability of the foam-type wick is shown to be significantly higher than that of conventional wicks because of their high porosity.

Effect Of Hot Water Injection On Sandstone Permeability

DEFF Research Database (Denmark)

Rosenbrand, Esther; Fabricius, Ida Lykke

2012-01-01

of published results regarding the effect of temperature on sandstone permeability. These tests are performed with mineral oil, nitrogen gas, distilled water and solutions of NaCl, KCl, CaCl2 as well as brines that contain a mixture of salts. Thirteen sandstone formations, ranging from quartz arenites...... to formations with a significant fraction of fine particles including clay minerals are investigated. The porosities range from 0.10 to 0.30 and permeabilities span the range from 1 to 1000 md. To compare different rock types, specific surface is determined from permeability and porosity using Kozeny’s equation...... not account for all the permeability reductions observed. Permeablity reduction occurs both when distilled water is the saturating fluid as well as in tests with NaCl, KCl or CaCl2 solutions, however, this is not the case in tests with mineral oil or nitrogen gas. The formation of a filter cake or influx...

Use of digital image analysis to estimate fluid permeability of porous materials: Application of two-point correlation functions

International Nuclear Information System (INIS)

Berryman, J.G.; Blair, S.C.

1986-01-01

Scanning electron microscope images of cross sections of several porous specimens have been digitized and analyzed using image processing techniques. The porosity and specific surface area may be estimated directly from measured two-point spatial correlation functions. The measured values of porosity and image specific surface were combined with known values of electrical formation factors to estimate fluid permeability using one version of the Kozeny-Carman empirical relation. For glass bead samples with measured permeability values in the range of a few darcies, our estimates agree well ( +- 10--20%) with the measurements. For samples of Ironton-Galesville sandstone with a permeability in the range of hundreds of millidarcies, our best results agree with the laboratory measurements again within about 20%. For Berea sandstone with still lower permeability (tens of millidarcies), our predictions from the images agree within 10--30%. Best results for the sandstones were obtained by using the porosities obtained at magnifications of about 100 x (since less resolution and better statistics are required) and the image specific surface obtained at magnifications of about 500 x (since greater resolution is required)

Effects of reduction in porosity and permeability with depth on storage capacity and injectivity in deep saline aquifers: A case study from the Mount Simon Sandstone aquifer

Science.gov (United States)

Medina, C.R.; Rupp, J.A.; Barnes, D.A.

2011-01-01

The Upper Cambrian Mount Simon Sandstone is recognized as a deep saline reservoir that has significant potential for geological sequestration in the Midwestern region of the United States. Porosity and permeability values collected from core analyses in rocks from this formation and its lateral equivalents in Indiana, Kentucky, Michigan, and Ohio indicate a predictable relationship with depth owing to a reduction in the pore structure due to the effects of compaction and/or cementation, primarily as quartz overgrowths. The regional trend of decreasing porosity with depth is described by the equation: ??(d)=16.36??e-0.00039*d, where ?? is the porosity and d is the depth in m. The decrease of porosity with depth generally holds true on a basinwide scale. Bearing in mind local variations in lithologic and petrophysical character within the Mount Simon Sandstone, the source data that were used to predict porosity were utilized to estimate the pore volume available within the reservoir that could potentially serve as storage space for injected CO2. The potential storage capacity estimated for the Mount Simon Sandstone in the study area, using efficiency factors of 1%, 5%, 10%, and 15%, is 23,680, 118,418, 236,832, and 355,242 million metric tons of CO2, respectively. ?? 2010 Elsevier Ltd.

Oxide film defects in Al alloys and the formation of hydrogen- related porosity

International Nuclear Information System (INIS)

Griffiths, W D; Yue, Y; Gerrard, A J

2016-01-01

Double oxide film defects have also been held responsible for the origins of hydrogen porosity, where hydrogen dissolved in the Al melt passes into the interior atmosphere of the double oxide film defect causing it to inflate. However, this is in opposition to long- established evidence that H cannot readily diffuse through aluminium oxide. To investigate this further, samples of commercial purity Al were first degassed to remove their initial H content, and then heated to above their melting point and held in atmospheres of air and nitrogen respectively, to determine any differences in H pick-up. The experiment showed that samples held in an oxidising atmosphere, and having an oxide skin, picked up significantly less H than when the samples were held in a nitrogen atmosphere, which resulted in the formation of AlN in cracks in the oxide skin of the sample. It is suggested that double oxide film defects can give rise to hydrogen-related porosity, but this occurs more quickly when the oxygen in the original oxide film defect has been consumed by reaction with the surrounding melt and nitrogen reacts to form AlN, which is more permeable to H than alumina, more easily allowing the oxide film defect to give rise to a hydrogen pore. This is used to interpret results from an earlier synchrotron experiment, in which a small pore was seen to grow into a larger pore, while an adjacent large pore remained at a constant size. (paper)

Multiscale modelling of dual-porosity porous media; a computational pore-scale study for flow and solute transport

Science.gov (United States)

de Vries, Enno T.; Raoof, Amir; van Genuchten, Martinus Th.

2017-07-01

Many environmental and agricultural applications involve the transport of water and dissolved constituents through aggregated soil profiles, or porous media that are structured, fractured or macroporous in other ways. During the past several decades, various process-based macroscopic models have been used to simulate contaminant transport in such media. Many of these models consider advective-dispersive transport through relatively large inter-aggregate pore domains, while exchange with the smaller intra-aggregate pores is assumed to be controlled by diffusion. Exchange of solute between the two domains is often represented using a first-order mass transfer coefficient, which is commonly obtained by fitting to observed data. This study aims to understand and quantify the solute exchange term by applying a dual-porosity pore-scale network model to relatively large domains, and analysing the pore-scale results in terms of the classical dual-porosity (mobile-immobile) transport formulation. We examined the effects of key parameters (notably aggregate porosity and aggregate permeability) on the main dual-porosity model parameters, i.e., the mobile water fraction (ϕm) and the mass transfer coefficient (α). Results were obtained for a wide range of aggregate porosities (between 0.082 and 0.700). The effect of aggregate permeability was explored by varying pore throat sizes within the aggregates. Solute breakthrough curves (BTCs) obtained with the pore-scale network model at several locations along the domain were analysed using analytical solutions of the dual-porosity model to obtain estimates of ϕm and α. An increase in aggregate porosity was found to decrease ϕm and increase α, leading to considerable tailing in the BTCs. Changes in the aggregate pore throat size affected the relative flow velocity between the intra- and inter-aggregate domains. Higher flow velocities within the aggregates caused a change in the transport regime from diffusion dominated to more

Fractal Theory for Permeability Prediction, Venezuelan and USA Wells

Science.gov (United States)

Aldana, Milagrosa; Altamiranda, Dignorah; Cabrera, Ana

2014-05-01

Inferring petrophysical parameters such as permeability, porosity, water saturation, capillary pressure, etc, from the analysis of well logs or other available core data has always been of critical importance in the oil industry. Permeability in particular, which is considered to be a complex parameter, has been inferred using both empirical and theoretical techniques. The main goal of this work is to predict permeability values on different wells using Fractal Theory, based on a method proposed by Pape et al. (1999). This approach uses the relationship between permeability and the geometric form of the pore space of the rock. This method is based on the modified equation of Kozeny-Carman and a fractal pattern, which allows determining permeability as a function of the cementation exponent, porosity and the fractal dimension. Data from wells located in Venezuela and the United States of America are analyzed. Employing data of porosity and permeability obtained from core samples, and applying the Fractal Theory method, we calculated the prediction equations for each well. At the beginning, this was achieved by training with 50% of the data available for each well. Afterwards, these equations were tested inferring over 100% of the data to analyze possible trends in their distribution. This procedure gave excellent results in all the wells in spite of their geographic distance, generating permeability models with the potential to accurately predict permeability logs in the remaining parts of the well for which there are no core samples, using even porority logs. Additionally, empirical models were used to determine permeability and the results were compared with those obtained by applying the fractal method. The results indicated that, although there are empirical equations that give a proper adjustment, the prediction results obtained using fractal theory give a better fit to the core reference data.

Pore Structure and Diagenetic Controls on Relative Permeability: Implications for Enhanced Oil Recovery and CO2 Storage

Science.gov (United States)

Feldman, J.; Dewers, T. A.; Heath, J. E.; Cather, M.; Mozley, P.

2016-12-01

Multiphase flow in clay-bearing sandstones of the Morrow Sandstone governs the efficiency of CO2 storage and enhanced oil recovery at the Farnsworth Unit, Texas. This formation is the target for enhanced oil recovery and injection of one million metric ton of anthropogenically-sourced CO2. The sandstone hosts eight major flow units that exhibit distinct microstructural characteristics due to diagenesis, including: "clean" macro-porosity; quartz overgrowths constricting some pores; ghost grains; intergranular porosity filled by microporous authigenic clay; and feldspar dissolution. We examine the microstructural controls on macroscale (core scale) relative permeability and capillary pressure behavior through: X-ray computed tomography, Robomet.3d, and focused ion beam-scanning electron microscopy imaging of the pore structure of the major flow units of the Morrow Sandstone; relative permeability and capillary pressure in the laboratory using CO2, brine, and oil at reservoir pressure and effective stress conditions. The combined data sets inform links between patterns of diagenesis and multiphase flow. These data support multiphase reservoir simulation and performance assessment by the Southwest Regional Partnership on Carbon Sequestration (SWP). Funding for this project is provided by the U.S. Department of Energy's National Energy Technology Laboratory through the SWP under Award No. DE-FC26-05NT42591. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Can porosity affect the hyperspectral signature of sandy landscapes?

Science.gov (United States)

Baranoski, Gladimir V. G.; Kimmel, Bradley W.

2017-10-01

Porosity is a fundamental property of sand deposits found in a wide range of landscapes, from beaches to dune fields. As a primary determinant of the density and permeability of sediments, it represents a central element in geophysical studies involving basin modeling and coastal erosion as well as geoaccoustics and geochemical investigations aiming at the understanding of sediment transport and water diffusion properties of sandy landscapes. These applications highlight the importance of obtaining reliable porosity estimations, which remains an elusive task, notably through remote sensing. In this work, we aim to contribute to the strengthening of the knowledge basis required for the development of new technologies for the remote monitoring of environmentally-triggered changes in sandy landscapes. Accordingly, we employ an in silico investigation approach to assess the effects of porosity variations on the reflectance of sandy landscapes in the visible and near-infrared spectral domains. More specifically, we perform predictive computer simulations using SPLITS, a hyperspectral light transport model for particulate materials that takes into account actual sand characterization data. To the best of our knowledge, this work represents the first comprehensive investigation relating porosity to the reflectance responses of sandy landscapes. Our findings indicate that the putative dependence of these responses on porosity may be considerably less pronounced than its dependence on other properties such as grain size and shape. Hence, future initiatives for the remote quantification of porosity will likely require reflectance sensors with a high degree of sensitivity.

Lattice Boltzmann Simulation of Permeability and Tortuosity for Flow through Dense Porous Media

Directory of Open Access Journals (Sweden)

Ping Wang

2014-01-01

Full Text Available Discrete element method (DEM is used to produce dense and fixed porous media with rigid mono spheres. Lattice Boltzmann method (LBM is adopted to simulate the fluid flow in interval of dense spheres. To simulating the same physical problem, the permeability is obtained with different lattice number. We verify that the permeability is irrelevant to the body force and the media length along flow direction. The relationships between permeability, tortuosity and porosity, and sphere radius are researched, and the results are compared with those reported by other authors. The obtained results indicate that LBM is suited to fluid flow simulation of porous media due to its inherent theoretical advantages. The radius of sphere should have ten lattices at least and the media length along flow direction should be more than twenty radii. The force has no effect on the coefficient of permeability with the limitation of slow fluid flow. For mono spheres porous media sample, the relationship of permeability and porosity agrees well with the K-C equation, and the tortuosity decreases linearly with increasing porosity.

Unsaturated and Saturated Permeabilities of Fiber Reinforcement: Critics and Suggestions

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Chung Hae ePARK

2015-04-01

Full Text Available In general, permeability measurement results show a strong scattering according to the measurement method, the type of test fluid and the fluid injection condition, even though permeability is regarded as a unique property of porous medium. In particular, the discrepancy between the unsaturated and saturated permeabilities for the same fabric has been widely reported. In the literature, relative permeability has been adopted to model the unsaturated flow. This approach has some limits in the modeling of double-scale porosity medium. We address this issue of permeability measurement by rigorously examining the mass conservation condition. Finally, we identify that the pressure gradient is non-linear with positive curvature in the unsaturated flow and a misinterpretation of pressure gradient is the main reason for the difference between the saturated and unsaturated permeabilities of the same fiber reinforcement. We propose to use a fixed value of permeability and to modify the mass conservation equation if there are air voids which are entrapped inside the fiber tow. Finally, we also suggest some guidelines and future perspectives to obtain more consistent permeability measurement results.

Nonstationary porosity evolution in mixing zone in coastal carbonate aquifer using an alternative modeling approach.

Science.gov (United States)

Laabidi, Ezzeddine; Bouhlila, Rachida

2015-07-01

In the last few decades, hydrogeochemical problems have benefited from the strong interest in numerical modeling. One of the most recognized hydrogeochemical problems is the dissolution of the calcite in the mixing zone below limestone coastal aquifer. In many works, this problem has been modeled using a coupling algorithm between a density-dependent flow model and a geochemical model. A related difficulty is that, because of the high nonlinearity of the coupled set of equations, high computational effort is needed. During calcite dissolution, an increase in permeability can be identified, which can induce an increase in the penetration of the seawater into the aquifer. The majority of the previous studies used a fully coupled reactive transport model in order to model such problem. Romanov and Dreybrodt (J Hydrol 329:661-673, 2006) have used an alternative approach to quantify the porosity evolution in mixing zone below coastal carbonate aquifer at steady state. This approach is based on the analytic solution presented by Phillips (1991) in his book Flow and Reactions in Permeable Rock, which shows that it is possible to decouple the complex set of equation. This equation is proportional to the square of the salinity gradient, which can be calculated using a density driven flow code and to the reaction rate that can be calculated using a geochemical code. In this work, this equation is used in nonstationary step-by-step regime. At each time step, the quantity of the dissolved calcite is quantified, the change of porosity is calculated, and the permeability is updated. The reaction rate, which is the second derivate of the calcium equilibrium concentration in the equation, is calculated using the PHREEQC code (Parkhurst and Apello 1999). This result is used in GEODENS (Bouhlila 1999; Bouhlila and Laabidi 2008) to calculate change of the porosity after calculating the salinity gradient. For the next time step, the same protocol is used but using the updated porosity

A review of porosity-generating mechanisms in crustal shear zones

Science.gov (United States)

Fusseis, F.; Regenauer-Lieb, K.; Revets, S.

2009-04-01

Knowledge of the spatiotemporal characteristics of permeability is critical for the understanding of fluid migration in rocks. In diagenetic and metamorphic rocks different porosity-generating mechanisms contribute to permeability and so influence fluid migration and fluid/rock interaction. However, little is known about their relative contributions to the porosity architecture of a rock in a tectono-metamorphic environment. This presentation reviews porosity-generating mechanisms that affect fluid migration in shear zones, the most important crustal fluid conduits, in the context of the tectonometamorphic evolution of rocks. Mechanisms that generate porosity can be classified in a) those that involve the direct action of a fluid, b) processes in which a fluid partakes or that are supported by a fluid or c) mechanism that do not involve a fluid. a) Hydraulic fracturing, where it happens through the formation of tensile fractures, occurs where pore fluid pressures equalize the combined lithostatic pressure and strength of the rock (Etheridge et al., 1984, Cox & Etheridge, 1989, Oliver, 1996). Here an internally released (devolatilisation reactions, e.g., Rumble, 1994, Hacker, 1997, Yardley, 1997 and references therein) or externally derived (infiltrating from metamorphic, magmatic or meteoric sources, Baumgartner et al., 1997, Jamtveit et al., 1997, Thompson, 1997, Gleeson et al., 2003) fluid directly causes the mechanical failure of a rock. Where a fluid is in chemical disequilibrium with a rock (undersaturated with regard to a chemical species) minerals will be dissolved, generating dissolution porosity. Rocks ‘leached' by the removal of chemical components by vast amounts of fluid are reported to lose up to 60% of their original volume (e.g., Kerrich et al., 1984, McCaig 1988). Dissolution porosity is probably an underrated porosity-generating mechanism. It can be expected along the entire metamorphic evolution, including diagenesis (Higgs et al., 2007) and

Carbonate porosity: some remarks; Porosidade em reservatorios carbonaticos: algumas consideracoes

Energy Technology Data Exchange (ETDEWEB)

Spadini, Adali Ricardo [PETROBRAS, Rio de Janeiro, RJ (Brazil). Exploracao e Producao]. E-mail: spadini@petrobras.com.br; Marcal, Rosely de Araujo [PETROBRAS, Rio de Janeiro, RJ (Brazil)

2005-05-01

Carbonate rocks are the major reservoirs of the largest super-giants fields in the world, including the Ghawar Field in Saudi Arabia, where the producing oil reservoir is the late Jurassic Arab-D limestone with five million barrels per day. Despite the great susceptibility to early diagenesis, that can dramatically modify the porous media, porosity values of carbonates remain essentially the same as that of deposition before burial. Porosity loss is essentially a subsurface process with a drastic reduction below 2500 m of burial depth. The occurrence of good reservoirs deeply buried, sometimes below 4,000 m, indicate that porosity can be preserved in subsurface in response to a series of mechanisms such as early oil emplacement, framework rigidity, abnormal pore pressure, among others. Percolation of geothermal fluids is a process considered to be responsible for generation of porosity in subsurface resulting in some good reservoir rocks. In Campos Basin, areas with burial around 2000 m, petrophysical data show a cyclic distribution that coincides with the shoaling upward cycles typical of the Albian carbonates. The greatest permeabilities coincide with the grain stones of the top of the cycles while the peloidal/oncolite wackestones/pack stones at the base show low values, reflecting the depositional texture. These relationships indicate that preservation of depositional porosity was very effective. The preservation of high porosity values for all the facies are related to early oil entrance in the reservoirs. In some cases, the presence of porosities of almost 30% in fine-grained peloidal carbonates, 3000 m of burial, without any clear effective preservation mechanism, suggest that corrosive subsurface brines have played an important role in porosity evolution. In Santos Basin, where reservoirs are deeply buried, only the grain stones have preserved porosity. The associated low energy facies has virtually no porosity. In this case, the depositional texture

Measurement of relative permeability of fuel cell diffusion media

KAUST Repository

Hussaini, I.S.

2010-06-01

Gas diffusion layer (GDL) in PEM fuel cells plays a pivotal role in water management. Modeling of liquid water transport through the GDL relies on knowledge of relative permeability functions in the in-plane and through-plane directions. In the present work, air and water relative permeabilities are experimentally determined as functions of saturation for typical GDL materials such as Toray-060, -090, -120 carbon paper and E-Tek carbon cloth materials in their plain, untreated forms. Saturation is measured using an ex situ gravimetric method. Absolute and relative permeability functions in the two directions of interest are presented and new correlations for in-plane relative permeability of water and air are established. © 2010 Elsevier B.V. All rights reserved.

Analytical Estimation of Water-Oil Relative Permeabilities through Fractures

Directory of Open Access Journals (Sweden)

Saboorian-Jooybari Hadi

2016-05-01

Full Text Available Modeling multiphase flow through fractures is a key issue for understanding flow mechanism and performance prediction of fractured petroleum reservoirs, geothermal reservoirs, underground aquifers and carbon-dioxide sequestration. One of the most challenging subjects in modeling of fractured petroleum reservoirs is quantifying fluids competition for flow in fracture network (relative permeability curves. Unfortunately, there is no standard technique for experimental measurement of relative permeabilities through fractures and the existing methods are very expensive, time consuming and erroneous. Although, several formulations were presented to calculate fracture relative permeability curves in the form of linear and power functions of flowing fluids saturation, it is still unclear what form of relative permeability curves must be used for proper modeling of flow through fractures and consequently accurate reservoir simulation. Basically, the classic linear relative permeability (X-type curves are used in almost all of reservoir simulators. In this work, basic fluid flow equations are combined to develop a new simple analytical model for water-oil two phase flow in a single fracture. The model gives rise to simple analytic formulations for fracture relative permeabilities. The model explicitly proves that water-oil relative permeabilities in fracture network are functions of fluids saturation, viscosity ratio, fluids density, inclination of fracture plane from horizon, pressure gradient along fracture and rock matrix wettability, however they were considered to be only functions of saturations in the classic X-type and power (Corey [35] and Honarpour et al. [28, 29] models. Eventually, validity of the proposed formulations is checked against literature experimental data. The proposed fracture relative permeability functions have several advantages over the existing ones. Firstly, they are explicit functions of the parameters which are known for

Permeability enhancement by shock cooling

Science.gov (United States)

Griffiths, Luke; Heap, Michael; Reuschlé, Thierry; Baud, Patrick; Schmittbuhl, Jean

2015-04-01

The permeability of an efficient reservoir, e.g. a geothermal reservoir, should be sufficient to permit the circulation of fluids. Generally speaking, permeability decreases over the life cycle of the geothermal system. As a result, is usually necessary to artificially maintain and enhance the natural permeability of these systems. One of the methods of enhancement -- studied here -- is thermal stimulation (injecting cold water at low pressure). This goal of this method is to encourage new thermal cracks within the reservoir host rocks, thereby increasing reservoir permeability. To investigate the development of thermal microcracking in the laboratory we selected two granites: a fine-grained (Garibaldi Grey granite, grain size = 0.5 mm) and a course-grained granite (Lanhelin granite, grain size = 2 mm). Both granites have an initial porosity of about 1%. Our samples were heated to a range of temperatures (100-1000 °C) and were either cooled slowly (1 °C/min) or shock cooled (100 °C/s). A systematic microstructural (2D crack area density, using standard stereological techniques, and 3D BET specific surface area measurements) and rock physical property (porosity, P-wave velocity, uniaxial compressive strength, and permeability) analysis was undertaken to understand the influence of slow and shock cooling on our reservoir granites. Microstructurally, we observe that the 2D crack surface area per unit volume and the specific surface area increase as a result of thermal stressing, and, for the same maximum temperature, crack surface area is higher in the shock cooled samples. This observation is echoed by our rock physical property measurements: we see greater changes for the shock cooled samples. We can conclude that shock cooling is an extremely efficient method of generating thermal microcracks and modifying rock physical properties. Our study highlights that thermal treatments are likely to be an efficient method for the "matrix" permeability enhancement of

Model-Assisted Control of Flow Front in Resin Transfer Molding Based on Real-Time Estimation of Permeability/Porosity Ratio

Directory of Open Access Journals (Sweden)

Bai-Jian Wei

2016-09-01

Full Text Available Resin transfer molding (RTM is a popular manufacturing technique that produces fiber reinforced polymer (FRP composites. In this paper, a model-assisted flow front control system is developed based on real-time estimation of permeability/porosity ratio using the information acquired by a visualization system. In the proposed control system, a radial basis function (RBF network meta-model is utilized to predict the position of the future flow front by inputting the injection pressure, the current position of flow front, and the estimated ratio. By conducting optimization based on the meta-model, the value of injection pressure to be implemented at each step is obtained. Moreover, a cascade control structure is established to further improve the control performance. Experiments show that the developed system successfully enhances the performance of flow front control in RTM. Especially, the cascade structure makes the control system robust to model mismatch.

Gyroid Nanoporous Membranes with Tunable Permeability

DEFF Research Database (Denmark)

Li, Li; Schulte, Lars; Clausen, Lydia D.

2011-01-01

-linked 1,2-polybutadiene (1,2-PB) membranes with uniform pores that, if needed, can be rendered hydrophilic. The gyroid porosity has the advantage of isotropic percolation with no need for structure prealignment. Closed (skin) or opened (nonskin) outer surface can be simply realized by altering...... the effective diffusion coefficients of a series of antibiotics, proteins, and other biomolecules; solute permeation is discussed in terms of hindered diffusion. The combination of uniform bulk morphology, isotropically percolating porosity, controlled surface chemistry, and tunable permeability is distinctive...

Fabrication of porous Al-Cu sintered body and its permeability property

Energy Technology Data Exchange (ETDEWEB)

Kim, Se-Hoon; Sung, Si-Young; Noh, Sang Ho; Kim, Sang Min [Korea Automotive Technology Institute, Cheonan (Korea, Republic of); Jin, Kwang Jin; Kim, Sang Min [Dongwon Technology Co., Kimhae (Korea, Republic of)

2014-01-15

In this study, porous Al-Cu sintered body was fabricated without any space-holder material and its properties, such as porosity, compressive yield strength, shore hardness, and permeability, were evaluated. Al-Cu powder mixtures were prepared by low-energy ball milling. The ball-milled powders were granulated and classified into size with <150 µm and 150-300 µm, and then they were compacted and sintered at 600 ℃ for 1 h in a vacuum and N{sub 2} atmosphere. The porosities of sintered bodies could be controlled in range of 15-48% by controlling the compaction pressure. The compressive yield strength and hardness were increased with a decreasing porosity. As a result, the mechanical properties and permeability of the optimized porous body were superior to that of commercial one.

Influence of compaction on the interfacial transition zone and the permeability of concrete

International Nuclear Information System (INIS)

Leemann, Andreas; Muench, Beat; Gasser, Philippe; Holzer, Lorenz

2006-01-01

The interfacial transition zone (ITZ) is regarded as a key feature for the transport properties and the durability of concrete. In this study one self-compacting concrete (SCC) mixture and two conventionally vibrated concrete (CVC) mixtures are studied in order to determine the influence of compaction on the porosity of the ITZ. Additionally oxygen permeability and water conductivity were measured in vertical and horizontal direction. The quantitative analysis of images made with an optical microscope and an environmental scanning electron microscope shows a significantly increased porosity and width of the ITZ in CVC compared to SCC. At the same time oxygen permeability and water conductivity of CVC are increased in comparison to SCC. Moreover, considerable differences in the porosity of the lower, lateral and upper ITZ are observed in both types of concrete. The anisotropic distribution of pores in the ITZ does not necessarily cause anisotropy in oxygen permeability and water conductivity though

Cross-property relations and permeability estimation in model porous media

International Nuclear Information System (INIS)

Schwartz, L.M.; Martys, N.; Bentz, D.P.; Garboczi, E.J.; Torquato, S.

1993-01-01

Results from a numerical study examining cross-property relations linking fluid permeability to diffusive and electrical properties are presented. Numerical solutions of the Stokes equations in three-dimensional consolidated granular packings are employed to provide a basis of comparison between different permeability estimates. Estimates based on the Λ parameter (a length derived from electrical conduction) and on d c (a length derived from immiscible displacement) are found to be considerably more reliable than estimates based on rigorous permeability bounds related to pore space diffusion. We propose two hybrid relations based on diffusion which provide more accurate estimates than either of the rigorous permeability bounds

The coupling of dynamics and permeability in the hydrocarbon accumulation period controls the oil-bearing potential of low permeability reservoirs: a case study of the low permeability turbidite reservoirs in the middle part of the third member of Shahejie Formation in Dongying Sag

DEFF Research Database (Denmark)

Yang, Tian; Cao, Ying-Chang; Wang, Yan-Zhong

2016-01-01

The relationships between permeability and dynamics in hydrocarbon accumulation determine oilbearing potential (the potential oil charge) of low permeability reservoirs. The evolution of porosity and permeability of low permeability turbidite reservoirs of the middle part of the third member...... facies A and diagenetic facies B do not develop accumulation conditions with low accumulation dynamics in the late accumulation period for very low permeability. At more than 3000 m burial depth, a larger proportion of turbidite reservoirs are oil charged due to the proximity to the source rock. Also...

An integrated approach to permeability modeling using micro-models

Energy Technology Data Exchange (ETDEWEB)

Hosseini, A.H.; Leuangthong, O.; Deutsch, C.V. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[Alberta Univ., Edmonton, AB (Canada)

2008-10-15

An important factor in predicting the performance of steam assisted gravity drainage (SAGD) well pairs is the spatial distribution of permeability. Complications that make the inference of a reliable porosity-permeability relationship impossible include the presence of short-scale variability in sand/shale sequences; preferential sampling of core data; and uncertainty in upscaling parameters. Micro-modelling is a simple and effective method for overcoming these complications. This paper proposed a micro-modeling approach to account for sampling bias, small laminated features with high permeability contrast, and uncertainty in upscaling parameters. The paper described the steps and challenges of micro-modeling and discussed the construction of binary mixture geo-blocks; flow simulation and upscaling; extended power law formalism (EPLF); and the application of micro-modeling and EPLF. An extended power-law formalism to account for changes in clean sand permeability as a function of macroscopic shale content was also proposed and tested against flow simulation results. There was close agreement between the model and simulation results. The proposed methodology was also applied to build the porosity-permeability relationship for laminated and brecciated facies of McMurray oil sands. Experimental data was in good agreement with the experimental data. 8 refs., 17 figs.

A new method to calculate permeability of gob for air leakage calculations and for improvements in methane control

Energy Technology Data Exchange (ETDEWEB)

Karacan, C.O. [National Inst. for Occupational Safety and Health, Pittsburgh, PA (United States). Office of Mine Safety and Health Research

2010-07-01

Although longwall underground mining can maximize coal production, it causes large scale disturbances of the surrounding rock mass due to fracturing and caving of the mine roof as the mine face advances. The porosity and permeability of the longwall gob can affect the methane and air flow patterns considerably. Since methane is a major hazard in underground coal mining operations, extensive methane control techniques are used to supplement the existing mine ventilation system, such as gob gas ventholes (GGV). However, the gob is rarely accessible for performing direct measurements of porosity and permeability. Therefore, this study presented a fractal approach for calculating the porosity and permeability from the size distribution of broken rock material in the gob, which can be determined from image analyses. The fractal approach constructs flow equations and fractal crushing equations for granular materials to predict porosity for a completely fragmented porous medium. The virtual fragmented fractal porous medium is exposed to various uniaxial stresses to simulate gob compaction and porosity and permeability changes during this process. It was concluded that the use of this fractal approach will result in better predictions regarding the flow amount and flow patterns in the gob, and facilitate leakage calculations and methane control projections. 29 refs., 4 tabs., 5 figs.

Permeability in Rotliegend gas sandstones to gas and brine as predicted from NMR, mercury injection and image analysis

DEFF Research Database (Denmark)

Rosenbrand, Esther; Fabricius, Ida Lykke; Fisher, Quentin

2015-01-01

Permeability characterisation of low permeability, clay-rich gas sandstones is part of production forecasting and reservoir management. The physically based Kozeny (1927) equation linking permeability with porosity and pore size is derived for a porous medium with a homogeneous pore size, whereas...... the pore sizes in tight sandstones can range from nm to μm. Nuclear magnetic resonance (NMR) transverse relaxation was used to estimate a pore size distribution for 63 samples of Rotliegend sandstone. The surface relaxation parameter required to relate NMR to pore size is estimated by combination of NMR...

Synthetic Rock Analogue for Permeability Studies of Rock Salt with Mudstone

Directory of Open Access Journals (Sweden)

Hongwu Yin

2017-09-01

Full Text Available Knowledge about the permeability of surrounding rock (salt rock and mudstone interlayer is an important topic, which acts as a key parameter to characterize the tightness of gas storage. The goal of experiments that test the permeability of gas storage facilities in rock salt is to develop a synthetic analogue to use as a permeability model. To address the permeability of a mudstone/salt layered and mixed rock mass in Jintan, Jiangsu Province, synthetic mixed and layered specimens using the mudstone and the salt were fabricated for permeability testing. Because of the gas “slippage effect”, test results are corrected by the Klinkenberg method, and the permeability of specimens is obtained by regression fitting. The results show that the permeability of synthetic pure rock salt is 6.9 × 10−20 m2, and its porosity is 3.8%. The permeability of synthetic mudstone rock is 2.97 × 10−18 m2, with a porosity 17.8%. These results are close to those obtained from intact natural specimens. We also find that with the same mudstone content, the permeability of mixed specimens is about 40% higher than for the layered specimens, and with an increase in the mudstone content, the Klinkenberg permeability increases for both types of specimens. The permeability and mudstone content have a strong exponential relationship. When the mudstone content is below 40%, the permeability increases only slightly with mudstone content, whereas above this threshold, the permeability increases rapidly with mudstone content. The results of the study are of use in the assessment of the tightness of natural gas storage facilities in mudstone-rich rock salt formations in China.

Predicting permeability of regular tissue engineering scaffolds: scaling analysis of pore architecture, scaffold length, and fluid flow rate effects.

Science.gov (United States)

Rahbari, A; Montazerian, H; Davoodi, E; Homayoonfar, S

2017-02-01

The main aim of this research is to numerically obtain the permeability coefficient in the cylindrical scaffolds. For this purpose, a mathematical analysis was performed to derive an equation for desired porosity in terms of morphological parameters. Then, the considered cylindrical geometries were modeled and the permeability coefficient was calculated according to the velocity and pressure drop values based on the Darcy's law. In order to validate the accuracy of the present numerical solution, the obtained permeability coefficient was compared with the published experimental data. It was observed that this model can predict permeability with the utmost accuracy. Then, the effect of geometrical parameters including porosity, scaffold pore structure, unit cell size, and length of the scaffolds as well as entrance mass flow rate on the permeability of porous structures was studied. Furthermore, a parametric study with scaling laws analysis of sample length and mass flow rate effects on the permeability showed good fit to the obtained data. It can be concluded that the sensitivity of permeability is more noticeable at higher porosities. The present approach can be used to characterize and optimize the scaffold microstructure due to the necessity of cell growth and transferring considerations.

Fast Laplace solver approach to pore-scale permeability

Science.gov (United States)

Arns, C. H.; Adler, P. M.

2018-02-01

We introduce a powerful and easily implemented method to calculate the permeability of porous media at the pore scale using an approximation based on the Poiseulle equation to calculate permeability to fluid flow with a Laplace solver. The method consists of calculating the Euclidean distance map of the fluid phase to assign local conductivities and lends itself naturally to the treatment of multiscale problems. We compare with analytical solutions as well as experimental measurements and lattice Boltzmann calculations of permeability for Fontainebleau sandstone. The solver is significantly more stable than the lattice Boltzmann approach, uses less memory, and is significantly faster. Permeabilities are in excellent agreement over a wide range of porosities.

Compressible fluid flow through rocks of variable permeability

International Nuclear Information System (INIS)

Lin, W.

1977-01-01

The effectiveness of course-grained igneous rocks as shelters for burying radioactive waste can be assessed by determining the rock permeabilities at their in situ pressures and stresses. Analytical and numerical methods were used to solve differential equations of one-dimensional fluid flow through rocks with permeabilities from 10 4 to 1 nD. In these calculations, upstream and downstream reservoir volumes of 5, 50, and 500 cm 3 were used. The optimal size combinations of the two reservoirs were determined for measurements of permeability, stress, strain, acoustic velocity, and electrical conductivity on low-porosity, coarse-grained igneous rocks

Permeability of WIPP Salt During Damage Evolution and Healing

International Nuclear Information System (INIS)

BODNER, SOL R.; CHAN, KWAI S.; MUNSON, DARRELL E.

1999-01-01

The presence of damage in the form of microcracks can increase the permeability of salt. In this paper, an analytical formulation of the permeability of damaged rock salt is presented for both initially intact and porous conditions. The analysis shows that permeability is related to the connected (i.e., gas accessible) volumetric strain and porosity according to two different power-laws, which may be summed to give the overall behavior of a porous salt with damage. This relationship was incorporated into a constitutive model, known as the Multimechanism Deformation Coupled Fracture (MDCF) model, which has been formulated to describe the inelastic flow behavior of rock salt due to coupled creep, damage, and healing. The extended model was used to calculate the permeability of rock salt from the Waste Isolation Pilot Plant (WIPP) site under conditions where damage evolved with stress over a time period. Permeability changes resulting from both damage development under deviatoric stresses and damage healing under hydrostatic pressures were considered. The calculated results were compared against experimental data from the literature, which indicated that permeability in damaged intact WIPP salt depends on the magnitude of the gas accessible volumetric strain and not on the total volumetric strain. Consequently, the permeability of WIPP salt is significantly affected by the kinetics of crack closure, but shows little dependence on the kinetics of crack removal by sintering

Microstructure and permeability of the Whitby Mudstone (UK) as an analogue for the Posidonia shale (NL)

Science.gov (United States)

Houben, Maartje; Barnhoorn, Auke; Drury, Martyn; Peach, Colin; Spiers, Christopher

2015-04-01

In order to make gas productivity from a shale economically interesting we should find ways to better connect the in-situ pore network to the natural occurring and mechanical induced fractures in the rock. When trying to improve gas productivity a first aim is to understand gas storage and gas flow potential through the rock by investigating the microstructure and measure the matrix porosity and permeability of the unfractured shales. Using a combination of methods we have characterized the porosity and permeability of the Jet Dogger section of the Whitby Mudstone Formation (UK), which we use as an analogue for the Posidonia Shale (NL). The Posidonia shale is a possible unconventional source for gas in Northern Europe. A combination of Precision Ion Polishing (PIPS) and Scanning Electron Microscopy (SEM) has been used to investigate the microstructure and the pores. Microstructurally the circa 8 meter thick Jet section of the Whitby Mudstone Formation can be subdivided into a fossil rich (>15 %) top half with an organic matter content of 7-10% and a sub-mm laminated (alternating clay-rich, carbonate-rich, not necessarily fossils, layers) lower half were the organic matter content varies from 0.3-16%. In addition, any possible flow in the rock has to go through the fine-grained clay matrix (all grains 100 nm) is in the order of 0.5-2.5% and is not connected in 2D. Furthermore, overall more than 40% of the visible porosity is present within the clay matrix (sometimes even up to 80%). Porosity and pore size distributions for pores with smaller diameters (2 < diameter < 100 nm) were determined using Ar and N2 gas adsorption. The adsorption porosity was in the order of 1-5%, were we found 1-2.5% porosity for the top half of the section and 2-5% porosity for the bottom half. Ar gas permeability of the samples was measured on 1-inch diameter cores using Ar-gas-permeametry with a pressure step of 0.2 MPa. The permeability measured was in the order of 2•10-19 - 1•10

Permeability and pore structure connectivity of basic concrete formulations to use in near-surface repositories for radioactive wastes

International Nuclear Information System (INIS)

Tolentino, Evandro; Santos, Carlos Eduardo de Oliveira; Tello, Clédola Cássia Oliveira de

2017-01-01

The main concern of engineers who prepare concrete specifications for a particular application is to predict the deteriorative exposures that could cause concrete degradation over its intended service life. A durable concrete is able to resist destructive environmental conditions, without requiring excessive maintenance. Durability of cementitious materials largely depends on the possibilities of penetration of hazardous ions into the porous material with water as medium. Therefore, the water permeability of cementitious materials is related to its durability. Permeability and porosity should not instinctively be regarded as manifestations of the same phenomenon. Usually, when permeability increases, porosity increases as well. The connectivity of pore network exerts an important control on preferential flow into cementitious materials. This work presents results of quantitative evaluation of permeability and pore connectivity of Portland cement concretes. Two concrete mixture proportions with limestone and gneiss as coarse aggregate were produced. A modified polycarboxyl ether plasticizer GLENIUM 51 was added to one of the concrete mixtures in order to reduce the water content. Permeability tests were performed on all the specimens and a geometric modeling considering pore with cylindrical shape was applied in order to evaluate the pore network connectivity. The results showed that pore structure connectivity of concrete with plasticizer admixture decreased. The purpose of this research is to expand the knowledge concerning concrete durability and to provide the technical requirements related to the production the Brazilian near-surface repository of radioactive wastes. (author)

Permeability and pore structure connectivity of basic concrete formulations to use in near-surface repositories for radioactive wastes

Energy Technology Data Exchange (ETDEWEB)

Tolentino, Evandro; Santos, Carlos Eduardo de Oliveira [Centro Federal de Educação Tecnológica de Minas Gerais (CEFET-MG), Timóteo, MG (Brazil); Tello, Clédola Cássia Oliveira de, E-mail: tolentino@timoteo.cefetmg.br, E-mail: tellocc@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2017-07-01

The main concern of engineers who prepare concrete specifications for a particular application is to predict the deteriorative exposures that could cause concrete degradation over its intended service life. A durable concrete is able to resist destructive environmental conditions, without requiring excessive maintenance. Durability of cementitious materials largely depends on the possibilities of penetration of hazardous ions into the porous material with water as medium. Therefore, the water permeability of cementitious materials is related to its durability. Permeability and porosity should not instinctively be regarded as manifestations of the same phenomenon. Usually, when permeability increases, porosity increases as well. The connectivity of pore network exerts an important control on preferential flow into cementitious materials. This work presents results of quantitative evaluation of permeability and pore connectivity of Portland cement concretes. Two concrete mixture proportions with limestone and gneiss as coarse aggregate were produced. A modified polycarboxyl ether plasticizer GLENIUM 51 was added to one of the concrete mixtures in order to reduce the water content. Permeability tests were performed on all the specimens and a geometric modeling considering pore with cylindrical shape was applied in order to evaluate the pore network connectivity. The results showed that pore structure connectivity of concrete with plasticizer admixture decreased. The purpose of this research is to expand the knowledge concerning concrete durability and to provide the technical requirements related to the production the Brazilian near-surface repository of radioactive wastes. (author)

Laboratory-scale measurements of effective relative permeability for layered sands

Energy Technology Data Exchange (ETDEWEB)

Butts, M.G.; Korsgaard, S.

1996-12-31

Predictions of the impact of remediation or the extent of contamination resulting from spills of gasoline, solvents and other petroleum products, must often be made in complex geological environments. Such problems can be treated by introducing the concept of effective parameters that incorporate the effects of soil layering or other heterogeneities into a large-scale flow description. Studies that derive effective multiphase parameters are few, and approximations are required to treat the non-linear multiphase flow equations. The purpose of this study is to measure effective relative permeabilities for well-defined multi-layered soils at the laboratory scale. Relative permeabilities were determined for homogeneous and layered, unconsolidated sands using the method of Jones and Roszelle (1978). The experimental data show that endpoint relative permeabilities are important in defining the shape of the relative permeability curves, but these cannot be predicted by estimation methods base on capillary pressure data. The most significant feature of the measured effective relative permeability curves is that the entrapped (residual) oil saturation is significantly larger than the residual saturation of the individual layers. This observation agrees with previous theoretical predictions of large-scale entrapment Butts, 1993 and (1995). Enhanced entrapment in heterogeneous soils has several important implications for spill remediation, for example, the reduced efficiency of direct recovery. (au) 17 refs.

Laboratory-scale measurements of effective relative permeability for layered sands

International Nuclear Information System (INIS)

Butts, M.G.; Korsgaard, S.

1996-01-01

Predictions of the impact of remediation or the extent of contamination resulting from spills of gasoline, solvents and other petroleum products, must often be made in complex geological environments. Such problems can be treated by introducing the concept of effective parameters that incorporate the effects of soil layering or other heterogeneities into a large-scale flow description. Studies that derive effective multiphase parameters are few, and approximations are required to treat the non-linear multiphase flow equations. The purpose of this study is to measure effective relative permeabilities for well-defined multi-layered soils at the laboratory scale. Relative permeabilities were determined for homogeneous and layered, unconsolidated sands using the method of Jones and Roszelle (1978). The experimental data show that endpoint relative permeabilities are important in defining the shape of the relative permeability curves, but these cannot be predicted by estimation methods base on capillary pressure data. The most significant feature of the measured effective relative permeability curves is that the entrapped (residual) oil saturation is significantly larger than the residual saturation of the individual layers. This observation agrees with previous theoretical predictions of large-scale entrapment Butts, 1993 and (1995). Enhanced entrapment in heterogeneous soils has several important implications for spill remediation, for example, the reduced efficiency of direct recovery. (au) 17 refs

Stationary and Dynamic Permeability and Coupling Coefficient Measurements in Sintered Glass Bead Systems

Science.gov (United States)

Gueven, I.; Steeb, H.; Luding, S.

2014-12-01

Electrokinetic waves describe the coupling between seismic and electromagnetic waves that exist in porous media. The coupling between them arise from an electrochemical boundary layer between grain and fluid interface of saturated porous media. Acoustical waves cause a disturbance of the electrical fluid charge within the double layer, which therefore creates an electric streaming current (seismoelectric effect). Inversely, electromagnetic waves can generate mechanical signals (electroseismic effect). Electrokinetic conversion potentially combines high seismic resolution with good electromagnetic hydrocarbon sensitivity. The (stationary and frequency-dependent) streaming potential coefficient is a key property, which gives rise to the coupling between electromagnetic and acoustical waves. It depends strongly on the fluid conductivity, porosity, tortuosity, permeability, pore throat and zeta potential of porous media. We examine experimentally both, the stationary and dynamic permeabilities and coupling coefficients of sintered glass bead systems. For this purpose a multi-purpose measuring cell was developed which allows us to carry out - besides common ultrasound experiments - also to perform stationary and frequency-dependent permeability and coupling coefficient measurements. For the experiments sintered mono- and slightly polydisperse glass bead samples with different glass bead diameters between 0.4 and 8mm and porosities ranging between 21 and 39% were used. The stationary and dynamic permeability and streaming potential measurements are supported by μCT scans which enable us a deeper insight into the porous medium. Based on the μCT scans of the produced sintered glass bead samples essential influence parameters, like tortuosity, porosity, effective particle diameters and pore throats in different regions of the entire scanned region have been analyzed in detail to understand the laboratory experiments, cf. Illustration 1. In addition lattice Boltzmann

On the Representation of the Porosity-Pressure Relationship in General Subsurface Flow Codes

Science.gov (United States)

Birdsell, Daniel T.; Karra, Satish; Rajaram, Harihar

2018-02-01

The governing equations for subsurface flow codes in a deformable porous media are derived from the balance of fluid mass and Darcy's equation. One class of these codes, which we call general subsurface flow codes (GSFs), allow for more general constitutive relations for material properties such as porosity, permeability and density. Examples of GSFs include PFLOTRAN, FEHM, TOUGH2, STOMP, and some reservoir simulators such as BOAST. Depending on the constitutive relations used in GSFs, an inconsistency arises between the standard groundwater flow equation and the governing equation of GSFs, and we clarify that the reason for this inconsistency is because the Darcy's equation used in the GSFs should account for the velocity of fluid with respect to solid. Due to lack of awareness of this inconsistency, users of the GSFs tend to use a porosity-pressure relationship that comes from the standard groundwater flow equation and assumes that the relative velocity is already accounted for. For the Theis problem, we show that using this traditional relationship in the GSFs leads to significantly large errors. We propose an alternate porosity-pressure relationship that is consistent with the derivation of the governing equations in the GSFs where the solid velocity is not tracked, and show that, with this relationship, the results are more accurate for the Theis problem. The purpose of this note is to make the users and developers of these GSFs aware of this inconsistency and to advocate that the alternate porosity model derived here should be incorporated in GSFs.

Permeability and Microstructure of Suspension Plasma-Sprayed YSZ Electrolytes for SOFCs on Various Substrates

Science.gov (United States)

Marr, Michael; Kesler, Olivera

2012-12-01

Yttria-stabilized zirconia electrolyte coatings for solid oxide fuel cells were deposited by suspension plasma spraying using a range of spray conditions and a variety of substrates, including finely structured porous stainless steel disks and cathode layers on stainless steel supports. Electrolyte permeability values and trends were found to be highly dependent on which substrate was used. The most gas-tight electrolyte coatings were those deposited directly on the porous metal disks. With this substrate, permeability was reduced by increasing the torch power and reducing the stand-off distance to produce dense coating microstructures. On the substrates with cathodes, electrolyte permeability was reduced by increasing the stand-off distance, which reduced the formation of segmentation cracks and regions of aligned and concentrated porosity. The formation mechanisms of the various permeability-related coating features are discussed and strategies for reducing permeability are presented. The dependences of electrolyte deposition efficiency and surface roughness on process conditions and substrate properties are also presented.

Gravel-Sand-Clay Mixture Model for Predictions of Permeability and Velocity of Unconsolidated Sediments

Science.gov (United States)

Konishi, C.

2014-12-01

Gravel-sand-clay mixture model is proposed particularly for unconsolidated sediments to predict permeability and velocity from volume fractions of the three components (i.e. gravel, sand, and clay). A well-known sand-clay mixture model or bimodal mixture model treats clay contents as volume fraction of the small particle and the rest of the volume is considered as that of the large particle. This simple approach has been commonly accepted and has validated by many studies before. However, a collection of laboratory measurements of permeability and grain size distribution for unconsolidated samples show an impact of presence of another large particle; i.e. only a few percent of gravel particles increases the permeability of the sample significantly. This observation cannot be explained by the bimodal mixture model and it suggests the necessity of considering the gravel-sand-clay mixture model. In the proposed model, I consider the three volume fractions of each component instead of using only the clay contents. Sand becomes either larger or smaller particles in the three component mixture model, whereas it is always the large particle in the bimodal mixture model. The total porosity of the two cases, one is the case that the sand is smaller particle and the other is the case that the sand is larger particle, can be modeled independently from sand volume fraction by the same fashion in the bimodal model. However, the two cases can co-exist in one sample; thus, the total porosity of the mixed sample is calculated by weighted average of the two cases by the volume fractions of gravel and clay. The effective porosity is distinguished from the total porosity assuming that the porosity associated with clay is zero effective porosity. In addition, effective grain size can be computed from the volume fractions and representative grain sizes for each component. Using the effective porosity and the effective grain size, the permeability is predicted by Kozeny-Carman equation

The Effect of Volumetric Porosity on Roughness Element Drag

Science.gov (United States)

Gillies, John; Nickling, William; Nikolich, George; Etyemezian, Vicken

2016-04-01

the cubes and 0.525 for the mesh forms. Results from the study indicate that as volumetric porosity increases, the force of drag on an element increases although the 2-dimensional porosity remains unchanged for the case of the cube forms. The mesh forms show a similar result that with increasing number of internal forms present, drag increases, but the drag curves are different, suggesting the kind of porosity has an effect on drag. An important scaling parameter that controls drag on the cubes is the permeability (K) of the element, which is a function of the diameter of the tubes and the porosity. K seems to be of lesser importance for controlling drag on the mesh forms. We hypothesize that the drag force data do not universally collapse as a function of permeability due to Reynolds number dependency on flow conditions within the elements that can be laminar, transitional, or turbulent even though flow exterior to the forms is fully turbulent. For the mesh forms, the greatest effect on drag occurs with the addition of the first internal form with subsequent additions showing very little additional effect.

Permeability Prediction in Deep Coal Seam: A Case Study on the No. 3 Coal Seam of the Southern Qinshui Basin in China

Science.gov (United States)

2013-01-01

The coal permeability is an important parameter in mine methane control and coal bed methane (CBM) exploitation, which determines the practicability of methane extraction. Permeability prediction in deep coal seam plays a significant role in evaluating the practicability of CBM exploitation. The coal permeability depends on the coal fractures controlled by strata stress, gas pressure, and strata temperature which change with depth. The effect of the strata stress, gas pressure, and strata temperature on the coal (the coal matrix and fracture) under triaxial stress and strain conditions was studied. Then we got the change of coal porosity with strata stress, gas pressure, and strata temperature and established a coal permeability model under tri-axial stress and strain conditions. The permeability of the No. 3 coal seam of the Southern Qinshui Basin in China was predicted, which is consistent with that tested in the field. The effect of the sorption swelling on porosity (permeability) firstly increases rapidly and then slowly with the increase of depth. However, the effect of thermal expansion and effective stress compression on porosity (permeability) increases linearly with the increase of depth. The most effective way to improve the permeability in exploiting CBM or extracting methane is to reduce the effective stress. PMID:24396293

Insights into the dolomitization process and porosity modification in sucrosic dolostones, Avon Park Formation (Middle Eocene), East-Central Florida, U.S.A.

KAUST Repository

Maliva,, Robert G.

2011-03-01

The Avon Park Formation (middle Eocene) in central Florida, U.S.A., contains shallow-water carbonates that have been replaced by dolomite to varying degrees, ranging from partially replaced limestones, to highly porous sucrosic dolostones, to, less commonly, low-porosity dense dolostones. The relationships between dolomitization and porosity and permeability were studied focusing on three 305-m-long cores taken in the City of Daytona Beach. Stable-isotope data from pure dolostones (mean δ 18O = +3.91% V-PDB) indicate dolomite precipitation in Eocene penesaline pore waters, which would be expected to have been at or above saturation with respect to calcite. Nuclear magnetic log-derived porosity and permeability data indicate that dolomitization did not materially change total porosity values at the bed and formation scale, but did result in a general increase in pore size and an associated substantial increase in permeability compared to limestone precursors. Dolomitization differentially affects the porosity and permeability of carbonate strata on the scale of individual crystals, beds, and formations. At the crystal scale, dolomitization occurs in a volume-for-volume manner in which the space occupied by the former porous calcium carbonate is replaced by a solid dolomite crystal with an associated reduction in porosity. Dolomite crystal precipitation was principally responsible for calcite dissolution both at the actual site of dolomite crystal growth and in the adjoining rock mass. Carbonate is passively scavenged from the formation, which results in no significant porosity change at the formation scale. Moldic pores after allochems formed mainly in beds that experienced high degrees of dolomitization, which demonstrates the intimate association of the dolomitization process with carbonate dissolution. The model of force of crystallization-controlled replacement provides a plausible explanation for key observations concerning the dolomitization process in the

Insights into the dolomitization process and porosity modification in sucrosic dolostones, Avon Park Formation (Middle Eocene), East-Central Florida, U.S.A.

KAUST Repository

Maliva,, Robert G.; Budd, David A.; Clayton, Edward A.; Missimer, Thomas M.; Dickson, John Anthony D

2011-01-01

The Avon Park Formation (middle Eocene) in central Florida, U.S.A., contains shallow-water carbonates that have been replaced by dolomite to varying degrees, ranging from partially replaced limestones, to highly porous sucrosic dolostones, to, less commonly, low-porosity dense dolostones. The relationships between dolomitization and porosity and permeability were studied focusing on three 305-m-long cores taken in the City of Daytona Beach. Stable-isotope data from pure dolostones (mean δ 18O = +3.91% V-PDB) indicate dolomite precipitation in Eocene penesaline pore waters, which would be expected to have been at or above saturation with respect to calcite. Nuclear magnetic log-derived porosity and permeability data indicate that dolomitization did not materially change total porosity values at the bed and formation scale, but did result in a general increase in pore size and an associated substantial increase in permeability compared to limestone precursors. Dolomitization differentially affects the porosity and permeability of carbonate strata on the scale of individual crystals, beds, and formations. At the crystal scale, dolomitization occurs in a volume-for-volume manner in which the space occupied by the former porous calcium carbonate is replaced by a solid dolomite crystal with an associated reduction in porosity. Dolomite crystal precipitation was principally responsible for calcite dissolution both at the actual site of dolomite crystal growth and in the adjoining rock mass. Carbonate is passively scavenged from the formation, which results in no significant porosity change at the formation scale. Moldic pores after allochems formed mainly in beds that experienced high degrees of dolomitization, which demonstrates the intimate association of the dolomitization process with carbonate dissolution. The model of force of crystallization-controlled replacement provides a plausible explanation for key observations concerning the dolomitization process in the

Methane hydrate induced permeability modification for multiphase flow in unsaturated porous media

Science.gov (United States)

Seol, Yongkoo; Kneafsey, Timothy J.

2011-08-01

An experimental study was performed using X-ray computed tomography (CT) scanning to capture three-dimensional (3-D) methane hydrate distributions and potential discrete flow pathways in a sand pack sample. A numerical study was also performed to develop and analyze empirical relations that describe the impacts of hydrate accumulation habits within pore space (e.g., pore filling or grain cementing) on multiphase fluid migration. In the experimental study, water was injected into a hydrate-bearing sand sample that was monitored using an X-ray CT scanner. The CT images were converted into numerical grid elements, providing intrinsic sample data including porosity and phase saturations. The impacts of hydrate accumulation were examined by adapting empirical relations into the flow simulations as additional relations governing the evolution of absolute permeability of hydrate bearing sediment with hydrate deposition. The impacts of pore space hydrate accumulation habits on fluid migration were examined by comparing numerical predictions with experimentally measured water saturation distributions and breakthrough curves. A model case with 3-D heterogeneous initial conditions (hydrate saturation, porosity, and water saturation) and pore body-preferred hydrate accumulations best captured water migration behavior through the hydrate-bearing sample observed in the experiment. In the best matching model, absolute permeability in the hydrate bearing sample does not decrease significantly with increasing hydrate saturation until hydrate saturation reaches about 40%, after which it drops rapidly, and complete blockage of flow through the sample can occur as hydrate accumulations approach 70%. The result highlights the importance of permeability modification due to hydrate accumulation habits when predicting multiphase flow through high-saturation, reservoir quality hydrate-bearing sediments.

Porosity, single-phase permeability, and capillary pressure data from preliminary laboratory experiments on selected samples from Marker Bed 139 at the Waste Isolation Pilot Plant. Volume 3 of 3: Appendices C, D, E, and F

Energy Technology Data Exchange (ETDEWEB)

Howarth, S.M.; Christian-Frear, T.

1997-08-01

This volume contains the mineralogy, porosity, and permeability results from the Marker Bed 139 anhydrite specimens evaluated by TerraTek, Inc. for the Waste Isolation Pilot Plant. This volume also documents the brine recipe used by RE/SPEC, Inc., the parameter package submitted to Performance Assessment based on all the data, and a memo on the mixed Brooks and Corey two-phase characteristic curves.

Porosity, single-phase permeability, and capillary pressure data from preliminary laboratory experiments on selected samples from Marker Bed 139 at the Waste Isolation Pilot Plant. Volume 3 of 3: Appendices C, D, E, and F

International Nuclear Information System (INIS)

Howarth, S.M.; Christian-Frear, T.

1997-08-01

This volume contains the mineralogy, porosity, and permeability results from the Marker Bed 139 anhydrite specimens evaluated by TerraTek, Inc. for the Waste Isolation Pilot Plant. This volume also documents the brine recipe used by RE/SPEC, Inc., the parameter package submitted to Performance Assessment based on all the data, and a memo on the mixed Brooks and Corey two-phase characteristic curves

Effective permeability in micropores from molecular simulations

International Nuclear Information System (INIS)

Botan, A.; Vermorel, R.; Brochard, L.; Hantal, G.; Pellenq, R.

2012-01-01

Document available in extended abstract form only. Despite many years' efforts and a large numbers of proposed models, the description of transport properties in clays is still an open question. The reason for this is that structurally clay is an extremely heterogeneous material. The pore size varies from a few to 20 angstroms for interlayer (micro) porosity, from 20 A to 500 A for interparticle (meso) porosity, and 500 A to μm and more for natural (macro) fractures. One further problem with the description of the transport properties is the presence of adsorption/desorption processes onto clay particles, which are coupled with swelling/shrinkage of the particles. Any volumetric changes in the particles affect the meso-pore aperture, and thus, the total permeability of the system. The various processes affecting the permeability occur on different spatial and temporal scales, that requires a multi-scale modeling approach. The most complete model to date is a dual porosity mode. Here the total flow is often written as a sum of the macropore flow and micropore flow. The flow through macro-pores is generally considered to be laminar and obeys Darcy's law, whereas flow through the matrix (micropore flow) may be modeled using Fick's law. The micropore flow involves both Knudsen and surface diffusion mechanisms. An accurate accounting of adsorption-desorption processes or the consideration of binary mixture greatly complicate analytical description. The goal of this study is to improve macro-scale model, the dual porosity model, for the transport properties of fluids in micropores from molecular simulations. The main idea is that we reproduce an experimental set-up used for permeability measurements, as illustrated in Figure 1. High density and low density regions are settled at each end of the membrane that allows to attain a steady flow. The densities in these regions are controlled by Grand Canonical Monte Carlo simulation; the molecular motions are described by

A derivative-free approach for the estimation of porosity and permeability using time-lapse seismic and production data

International Nuclear Information System (INIS)

Dadashpour, Mohsen; Kleppe, Jon; Landrø, Martin; Echeverria Ciaurri, David; Mukerji, Tapan

2010-01-01

In this study, we apply a derivative-free optimization algorithm to estimate porosity and permeability from time-lapse seismic data and production data from a real reservoir (Norne field). In some circumstances, obtaining gradient information (exact and/or approximate) can be problematic e.g. derivatives are not available from a commercial simulator, or results are needed within a very short time frame. Derivative-free optimization approaches can be very time consuming because they often require many simulations. Typically, one iteration roughly needs as many simulations as the number of optimization variables. In this work, we propose two ways to significantly increase the efficiency of an optimization methodology in model inversion problems. First, by principal component analysis we decrease the number of optimization variables while keeping geostatistical consistency, and second, noticing that some optimization methods are very amenable to being parallelized, we apply them within a distributed computing framework. If we combine all this, the model inversion approach can be robust, fairly efficient and very simple to implement. In this paper, we apply the methodology to two cases: a semi-synthetic model with noisy data, and a case based entirely on field data. The results show that the derivative-free approach presented is robust against noise in the data

Numerical modeling of porosity waves in the Nankai accretionary wedge décollement, Japan: implications for aseismic slip

Science.gov (United States)

Joshi, Ajit; Appold, Martin S.

2017-01-01

Seismic and hydrologic observations of the Nankai accretionary wedge décollement, Japan, show that overpressures at depths greater than ˜2 km beneath the seafloor could have increased to near lithostatic values due to sediment compaction and diagenesis, clay dehydration, and shearing. The resultant high overpressures are hypothesized then to have migrated in rapid surges or pulses called `porosity waves' up the dip of the décollement. Such high velocities—much higher than expected Darcy fluxes—are possible for porosity waves if the porous media through which the waves travel are deformable enough for porosity and permeability to increase strongly with increasing fluid pressure. The present study aimed to test the hypothesis that porosity waves can travel at rates (kilometers per day) fast enough to cause aseismic slip in the Nankai décollement. The hypothesis was tested using a one-dimensional numerical solution to the fluid mass conservation equation for elastic porous media. Results show that porosity waves generated at depths of ˜2 km from overpressures in excess of lithostatic pressure can propagate at rates sufficient to account for aseismic slip along the décollement over a wide range of hydrogeological conditions. Sensitivity analysis showed porosity wave velocity to be strongly dependent on specific storage, fluid viscosity, and the permeability-depth gradient. Overpressure slightly less than lithostatic pressure could also produce porosity waves capable of traveling at velocities sufficient to cause aseismic slip, provided that hydrogeologic properties of the décollement are near the limits of their geologically reasonable ranges.

A new method for the experimental determination of three-phase relative permeabilities

International Nuclear Information System (INIS)

Perez Carrillo, Edgar Ricardo; Jose Francisco Zapata Arango; Santos Santos, Nicolas

2008-01-01

Petroleum reservoirs under primary, secondary or tertiary recovery processes usually experience simultaneous flow of three fluids phases (oil, water and gas). Reports on some mathematical models for calculating three-phase relative permeability are available in the Literature. Nevertheless, many of these models were designed based on certain experimental conditions and reservoir rocks and fluids. Therefore, special care has to be taken when applying them to specific reservoirs. At the laboratory level, three-phase relative permeability can be calculated using experimental unsteady-state or steady state methodologies. This paper proposes an unsteady-state methodology to evaluate three-phase relative permeability using the equipment available at the petrophysical analysis Laboratory of the Instituto Colombiano del Petroleo (ICP) of Ecopetrol S.A. Improvements to the equipment were effected in order to achieve accuracy in the unsteady-state measurement of three-phase relative permeability. The target of improvements was directed toward to the attainment of two objectives:1) the modification of the equipment to obtain more reliable experimental data and 2) the appropriate interpretation of the data obtained. Special attention was given to the differential pressure and uncertainty measurement in the determination of fluid saturation in the rock samples. Three experiments for three-phase relative permeability were conducted using a sample A and reservoir rock from the Colombian Foothills. Fluid tests included the utilization of synthetic brine, mineral oil, reservoir crude oil and nitrogen. Two runs were conducted at the laboratory conditions while one run was conducted at reservoir conditions. Experimental results of these tests were compared using 16 mathematical models of three-phase relative permeability. For the three-phase relative permeability to oil, the best correlations between experimental data and tests using Blunt, Hustad Hasen, and Baker's models were

Experimental Measurement of Relative Permeability Functions for Fuel Cell GDL Materials

KAUST Repository

Hussaini, Irfan; Wang, Chao-Yang

2009-01-01

Gas diffusion layer in PEM fuel cells plays a pivotal role in water management. Modeling of liquid water transport through the GDL relies on knowledge of relative permeability functions in the in-plane and through-plane directions. In the present work, air and water relative permeabilities are experimentally determined as functions of saturation for typical GDL materials such as Toray-060, -090, -120 carbon paper and E-Tek carbon cloth materials in their plain, untreated forms. Saturation is measured using an ex-situ gravimetric method. Absolute and relative permeability functions in the two directions of interest are presented. Significant departure from the generally assumed cubic function of saturation is observed. ©The Electrochemical Society.

Fluid flow simulation and permeability computation in deformed porous carbonate grainstones

Science.gov (United States)

Zambrano, Miller; Tondi, Emanuele; Mancini, Lucia; Lanzafame, Gabriele; Trias, F. Xavier; Arzilli, Fabio; Materazzi, Marco; Torrieri, Stefano

2018-05-01

In deformed porous carbonates, the architecture of the pore network may be modified by deformation or diagenetic processes altering the permeability with respect to the pristine rock. The effects of the pore texture and morphology on permeability in porous rocks have been widely investigated due to the importance during the evaluation of geofluid reservoirs. In this study, these effects are assessed by combining synchrotron X-ray computed microtomography (SR micro-CT) and computational fluid dynamics. The studied samples pertain to deformed porous carbonate grainstones highly affected by deformation bands (DBs) exposed in Northwestern Sicily and Abruzzo regions, Italy. The high-resolution SR micro-CT images of the samples, acquired at the SYRMEP beamline of the Elettra - Sincrotrone Trieste laboratory (Italy), were used for simulating a pressure-driven flow by using the lattice-Boltzmann method (LBM). For the experiments, a multiple relaxation time (MRT) model with the D3Q19 scheme was used to avoid viscosity-dependent results of permeability. The permeability was calculated using Darcy's law once steady conditions were reached. After the simulations, the pore-network properties (effective porosity, specific surface area, and geometrical tortuosity) were calculated using 3D images of the velocity fields. These images were segmented considering a velocity threshold value higher than zero. The study showed that DBs may generate significant heterogeneity and anisotropy of the permeability of the evaluated rock samples. Cataclasis and cementation process taking place within the DBs reduce the effective porosity and therefore the permeability. Contrary to this, pressure dissolution and faulting may generate connected channels which contribute to the permeability only parallel to the DB.

Bioinspired Layer-by-Layer Microcapsules Based on Cellulose Nanofibers with Switchable Permeability

DEFF Research Database (Denmark)

Paulraj, Thomas; Riazanova, Anastasia V; Yao, Kun

2017-01-01

Green, all-polysaccharide based microcapsules with mechanically robust capsule walls and fast, stimuli-triggered, and switchable permeability behavior show great promise in applications based on selective and timed permeability. Taking a cue from nature, the build-up and composition of plant......-by-layer technique on sacrificial CaCO3 templates, using plant polysaccharides (pectin, cellulose nanofibers, and xyloglucan) only. In water, the capsule wall was permeable to labeled dextrans with a hydrodynamic diameter of ∼6.6 nm. Upon exposure to NaCl, the porosity of the capsule wall quickly changed allowing...

Controls on magma permeability in the volcanic conduit during the climactic phase of the Kos Plateau Tuff eruption (Aegean Arc)

Science.gov (United States)

Degruyter, W.; Bachmann, O.; Burgisser, A.

2010-01-01

X-ray computed microtomography (µCT) was applied to pumices from the largest Quaternary explosive eruption of the active South Aegean Arc (the Kos Plateau Tuff; KPT) in order to better understand magma permeability within volcanic conduits. Two different types of pumices (one with highly elongated bubbles, tube pumice; and the other with near spherical bubbles, frothy pumice) produced synchronously and with identical chemical composition were selected for µCT imaging to obtain porosity, tortuosity, bubble size and throat size distributions. Tortuosity drops on average from 2.2 in frothy pumice to 1.5 in tube pumice. Bubble size and throat size distributions provide estimates for mean bubble size (~93-98 μm) and mean throat size (~23-29 μm). Using a modified Kozeny-Carman equation, variations in porosity, tortuosity, and throat size observed in KPT pumices explain the spread found in laboratory measurements of the Darcian permeability. Measured difference in inertial permeability between tube and frothy pumices can also be partly explained by the same variables but require an additional parameter related to the internal roughness of the porous medium (friction factor f 0 ). Constitutive equations for both types of permeability allow the quantification of laminar and turbulent gas escape during ascent of rhyolitic magma in volcanic conduits.

Calculation of large scale relative permeabilities from stochastic properties of the permeability field and fluid properties

Energy Technology Data Exchange (ETDEWEB)

Lenormand, R.; Thiele, M.R. [Institut Francais du Petrole, Rueil Malmaison (France)

1997-08-01

The paper describes the method and presents preliminary results for the calculation of homogenized relative permeabilities using stochastic properties of the permeability field. In heterogeneous media, the spreading of an injected fluid is mainly sue to the permeability heterogeneity and viscosity fingering. At large scale, when the heterogeneous medium is replaced by a homogeneous one, we need to introduce a homogenized (or pseudo) relative permeability to obtain the same spreading. Generally, is derived by using fine-grid numerical simulations (Kyte and Berry). However, this operation is time consuming and cannot be performed for all the meshes of the reservoir. We propose an alternate method which uses the information given by the stochastic properties of the field without any numerical simulation. The method is based on recent developments on homogenized transport equations (the {open_quotes}MHD{close_quotes} equation, Lenormand SPE 30797). The MHD equation accounts for the three basic mechanisms of spreading of the injected fluid: (1) Dispersive spreading due to small scale randomness, characterized by a macrodispersion coefficient D. (2) Convective spreading due to large scale heterogeneities (layers) characterized by a heterogeneity factor H. (3) Viscous fingering characterized by an apparent viscosity ration M. In the paper, we first derive the parameters D and H as functions of variance and correlation length of the permeability field. The results are shown to be in good agreement with fine-grid simulations. The are then derived a function of D, H and M. The main result is that this approach lead to a time dependent . Finally, the calculated are compared to the values derived by history matching using fine-grid numerical simulations.

Thermal radiation effects on magnetohydrodynamic free convection heat and mass transfer from a sphere in a variable porosity regime

KAUST Repository

Prasad, Vallampati Ramachandra Ramachandra

2012-02-01

A mathematical model is presented for multiphysical transport of an optically-dense, electrically-conducting fluid along a permeable isothermal sphere embedded in a variable-porosity medium. A constant, static, magnetic field is applied transverse to the cylinder surface. The non-Darcy effects are simulated via second order Forchheimer drag force term in the momentum boundary layer equation. The surface of the sphere is maintained at a constant temperature and concentration and is permeable, i.e. transpiration into and from the boundary layer regime is possible. The boundary layer conservation equations, which are parabolic in nature, are normalized into non-similar form and then solved numerically with the well-tested, efficient, implicit, stable Keller-box finite difference scheme. Increasing porosity (ε) is found to elevate velocities, i.e. accelerate the flow but decrease temperatures, i.e. cool the boundary layer regime. Increasing Forchheimer inertial drag parameter (Λ) retards the flow considerably but enhances temperatures. Increasing Darcy number accelerates the flow due to a corresponding rise in permeability of the regime and concomitant decrease in Darcian impedance. Thermal radiation is seen to reduce both velocity and temperature in the boundary layer. Local Nusselt number is also found to be enhanced with increasing both porosity and radiation parameters. © 2011 Elsevier B.V.

EXPERIMENTAL DETERMINATION OF VARIABILITY IN PERMEABILITY OF SANDY SILT SOIL MIXED WITH FLY ASH IN PROPORTIONATE

OpenAIRE

Rasna Sharma*, Dr. M.K. Trivedi

2016-01-01

This paper presents the experimental determination of variability in permeability of sandy silt soil by blending with fly ash. The grain size, porosity, structure of the soil, specific gravity of the soil, viscosity and temperature are important factors in varying the permeability of the soil. Permeability is the flow conduction property of the soil. The void ratio with in the soil plays a vital role in varying the permeability. By blending with finer grains like fly ash in the soil with sand...

Flow visualization and relative permeability measurements in rough-walled fractures

International Nuclear Information System (INIS)

Persoff, P.; Pruess, K.

1993-01-01

Two-phase (gas-liquid) flow experiments were done in a natural rock fracture and transparent replicas of natural fractures. Liquid was injected at constant volume flow rate, and gas was injected at either constant mass flow rate or constant pressure. When gas was injected at constant mass flow rate, the gas inlet pressure, and inlet and outlet capillary pressures, generally did not reach steady state but cycled irregularly. Flow visualization showed that this cycling was due to repeated blocking and unblocking of gas flow paths by liquid. Relative permeabilities calculated from flow rate and pressure data show that the sum of the relative permeabilities of the two phases is much less than 1, indicating that each phase interferes strongly with the flow of the other. Comparison of the relative permeability curves with typical curves for porous media (Corey curves) show that the phase interference is stronger in fractures than in typical porous media

Evolution of porosity and diffusivity associated with chemical weathering of a basalt clast

Energy Technology Data Exchange (ETDEWEB)

Navarre-Sitchler, A.; Steefel, C.I.; Yang, L.; Tomutsa, L.; Brantley, S.L.

2009-02-15

Weathering of rocks as a result of exposure to water and the atmosphere can cause significant changes in their chemistry and porosity. In low-porosity rocks, such as basalts, changes in porosity, resulting from chemical weathering, are likely to modify the rock's effective diffusivity and permeability, affecting the rate of solute transport and thus potentially the rate of overall weathering to the extent that transport is the rate limiting step. Changes in total porosity as a result of mineral dissolution and precipitation have typically been used to calculate effective diffusion coefficients through Archie's law for reactive transport simulations of chemical weathering, but this approach fails to account for unconnected porosity that does not contribute to transport. In this study, we combine synchrotron X-ray microcomputed tomography ({mu}CT) and laboratory and numerical diffusion experiments to examine changes in both total and effective porosity and effective diffusion coefficients across a weathering interface in a weathered basalt clast from Costa Rica. The {mu}CT data indicate that below a critical value of {approx}9%, the porosity is largely unconnected in the basalt clast. The {mu}CT data were further used to construct a numerical pore network model to determine upscaled, effective diffusivities as a function of total porosity (ranging from 3 to 30%) for comparison with diffusivities determined in laboratory tracer experiments. By using effective porosity as the scaling parameter and accounting for critical porosity, a model is developed that accurately predicts continuum-scale effective diffusivities across the weathering interface of the basalt clast.

Geochemical porosity values obtained in core samples from different clay-rocks

International Nuclear Information System (INIS)

Fernandez, A.M.

2010-01-01

Document available in extended abstract form only. Argillaceous formations of low permeability are considered in many countries as potential host rocks for the disposal of high level radioactive wastes (HLRW). In order to determine their suitability for waste disposal, evaluations of the hydro-geochemistry and transport mechanisms from such geologic formations to the biosphere must be undertaken. One of the key questions about radionuclide diffusion and retention is to know the chemistry and chemical reactions and sorption processes that will occur in the rock and their effects on radionuclide mobility. In this context, the knowledge of the pore water chemistry is essential for performance assessment purposes. This information allows to establish a reliable model for the main water-rock interactions, which control the physico-chemical parameters and the chemistry of the major elements of the system. An important issue in order to model the pore water chemistry in clayey media is to determine the respective volume accessible to cations and anions, i.e, the amount of water actually available for chemical reactions/solute transport. This amount is usually referred as accessible porosity or geochemical porosity. By using the anion inventories, i.e. the anion content obtained from aqueous leaching, and assuming that all Cl - , Br - and SO4 2- leached in the aqueous extracts originates from pore water, the concentration of a conservative ion can be converted into the real pore water concentration if the accessible porosity is known. In this work, the accessible porosity or geochemical porosity has been determined in core samples belonging to four different formations: Boom Clay from Hades URL (Belgium, BE), Opalinus Clay from Mont Terri (Switzerland, CH), and Callovo-Oxfordian argillite from Bure URL (France, FR). The geochemical or chloride porosity was defined as the ratio between the pore water volume containing Cl-bearing pore water and the total volume of a sample

Modeled near-field environment porosity modifications due to coupled thermohydrologic and geochemical processes

International Nuclear Information System (INIS)

Glassley, W. E.; Nitao, J. J.

1998-01-01

Heat deposited by waste packages in nuclear waste repositories can modify rock properties by instigating mineral dissolution and precipitation along hydrothermal flow pathways. Modeling this reactive transport requires coupling fluid flow to permeability changes resulting from dissolution and precipitation. Modification of the NUFT thermohydrologic (TH) code package to account for this coupling in a simplified geochemical system has been used to model the time- dependent change in porosity, permeability, matrix and fracture saturation, and temperature in the vicinity of waste-emplacement drifts, using conditions anticipated for the potential Yucca Mountain repository. The results show, within a few hundred years, dramatic porosity reduction approximately 10 m above emplacement drifts. Most of this reduction is attributed to deposition of solute load at the boiling front, although some of it also results from decreasing temperature along the flow path. The actual distribution of the nearly sealed region is sensitive to the time- dependent characteristics of the thermal load imposed on the environment and suggests that the geometry of the sealed region can be engineered by managing the waste-emplacement strategy

Industrial waste as a source for fabrication of composite ceramics-glass with a controlled porosity

Directory of Open Access Journals (Sweden)

Adziski R.

2008-01-01

Full Text Available Metallurgical slag with granulation (-0.125+0.063mm and 20 wt% waste TV glass were used for obtaining a glass ceramic composite with a controlled porosity. This material obtained by sintering at 950oC/2h possessed thermal stability, integral porosity of 43.6% and E-modulus and bending strength of 12 GPa and 39 MPa, respectively. The composite was characterized with a permeability of 0.47 Da and generation of air bubbles with size of 1-4 mm in a water medium.

An improved method for permeability estimation of the bioclastic limestone reservoir based on NMR data

Science.gov (United States)

Ge, Xinmin; Fan, Yiren; Liu, Jianyu; Zhang, Li; Han, Yujiao; Xing, Donghui

2017-10-01

Permeability is an important parameter in formation evaluation since it controls the fluid transportation of porous rocks. However, it is challengeable to compute the permeability of bioclastic limestone reservoirs by conventional methods linking petrophysical and geophysical data, due to the complex pore distributions. A new method is presented to estimate the permeability based on laboratory and downhole nuclear magnetic resonance (NMR) measurements. We divide the pore space into four intervals by the inflection points between the pore radius and the transversal relaxation time. Relationships between permeability and percentages of different pore intervals are investigated to investigate influential factors on the fluid transportation. Furthermore, an empirical model, which takes into account of the pore size distributions, is presented to compute the permeability. 212 core samples in our case show that the accuracy of permeability calculation is improved from 0.542 (SDR model), 0.507 (TIM model), 0.455 (conventional porosity-permeability regressions) to 0.803. To enhance the precision of downhole application of the new model, we developed a fluid correction algorithm to construct the water spectrum of in-situ NMR data, aiming to eliminate the influence of oil on the magnetization. The result reveals that permeability is positively correlated with percentages of mega-pores and macro-pores, but negatively correlated with the percentage of micro-pores. Poor correlation is observed between permeability and the percentage of meso-pores. NMR magnetizations and T2 spectrums after the fluid correction agree well with laboratory results for samples saturated with water. Field application indicates that the improved method provides better performance than conventional models such as Schlumberger-Doll Research equation, Timur-Coates equation, and porosity-permeability regressions.

Quantifying multiscale porosity and fracture aperture distribution in granite cores using computed tomography

Science.gov (United States)

Wenning, Quinn; Madonna, Claudio; Joss, Lisa; Pini, Ronny

2017-04-01

Knowledge of porosity and fracture (aperture) distribution is key towards a sound description of fluid transport in low-permeability rocks. In the context of geothermal energy development, the ability to quantify the transport properties of fractures is needed to in turn quantify the rate of heat transfer, and, accordingly, to optimize the engineering design of the operation. In this context, core-flooding experiments coupled with non-invasive imaging techniques (e.g., X-Ray Computed Tomography - X-Ray CT) represent a powerful tool for making direct observations of these properties under representative geologic conditions. This study focuses on quantifying porosity and fracture aperture distribution in a fractured westerly granite core by using two recently developed experimental protocols. The latter include the use of a highly attenuating gas [Vega et al., 2014] and the application of the so-called missing CT attenuation method [Huo et al., 2016] to produce multidimensional maps of the pore space and of the fractures. Prior to the imaging experiments, the westerly granite core (diameter: 5 cm, length: 10 cm) was thermally shocked to induce micro-fractured pore space; this was followed by the application of the so-called Brazilian method to induce a macroscopic fracture along the length of the core. The sample was then mounted in a high-pressure aluminum core-holder, exposed to a confining pressure and placed inside a medical CT scanner for imaging. An initial compressive pressure cycle was performed to remove weak asperities and reduce the hysteretic behavior of the fracture with respect to effective pressure. The CT scans were acquired at room temperature and 0.5, 5, 7, and 10 MPa effective pressure under loading and unloading conditions. During scanning the pore fluid pressure was undrained and constant, and the confining pressure was regulated at the desired pressure with a high precision pump. Highly transmissible krypton and helium gases were used as

Integrated petrophysical and reservoir characterization workflow to enhance permeability and water saturation prediction

Science.gov (United States)

Al-Amri, Meshal; Mahmoud, Mohamed; Elkatatny, Salaheldin; Al-Yousef, Hasan; Al-Ghamdi, Tariq

2017-07-01

Accurate estimation of permeability is essential in reservoir characterization and in determining fluid flow in porous media which greatly assists optimize the production of a field. Some of the permeability prediction techniques such as Porosity-Permeability transforms and recently artificial intelligence and neural networks are encouraging but still show moderate to good match to core data. This could be due to limitation to homogenous media while the knowledge about geology and heterogeneity is indirectly related or absent. The use of geological information from core description as in Lithofacies which includes digenetic information show a link to permeability when categorized into rock types exposed to similar depositional environment. The objective of this paper is to develop a robust combined workflow integrating geology and petrophysics and wireline logs in an extremely heterogeneous carbonate reservoir to accurately predict permeability. Permeability prediction is carried out using pattern recognition algorithm called multi-resolution graph-based clustering (MRGC). We will bench mark the prediction results with hard data from core and well test analysis. As a result, we showed how much better improvements are achieved in the permeability prediction when geology is integrated within the analysis. Finally, we use the predicted permeability as an input parameter in J-function and correct for uncertainties in saturation calculation produced by wireline logs using the classical Archie equation. Eventually, high level of confidence in hydrocarbon volumes estimation is reached when robust permeability and saturation height functions are estimated in presence of important geological details that are petrophysically meaningful.

Thermal radiation effects on magnetohydrodynamic free convection heat and mass transfer from a sphere in a variable porosity regime

KAUST Repository

Prasad, Vallampati Ramachandra Ramachandra; Vasu, Buddakkagari; Bé g, Osman Anwar; Parshad, Rana

2012-01-01

A mathematical model is presented for multiphysical transport of an optically-dense, electrically-conducting fluid along a permeable isothermal sphere embedded in a variable-porosity medium. A constant, static, magnetic field is applied transverse

Porosity of Self-Compacting Concrete (SCC) incorporating high volume fly ash

Science.gov (United States)

Kristiawan, S. A.; Sunarmasto; Murti, G. Y.

2017-02-01

Degradation of concrete could be triggered by the presence of aggressive agents from the environment into the body of concrete. The penetration of these agents is influenced by the pore characteristics of the concrete. Incorporating a pozzolanic material such as fly ash could modify the pore characteristic of the concrete. This research aims to investigate the influence of incorporating fly ash at high volume level on the porosity of Self-Compacting Concrete (SCC). Laboratory investigations were carried out following the ASTM C642 for measuring density and volume of permeable pores (voids) of the SCC with varying fly ash contents (50-70% by weight of total binder). In addition, a measurement of permeable voids by saturation method was carried out to obtain an additional volume of voids that could not be measured by the immersion and boiling method of ASTM C642. The results show that the influence of fly ash content on the porosity appears to be dependent on age of SCC. At age less than 56 d, fly ash tends to cause an increase of voids but at 90 d of age it reduces the pores. The additional pores that can be penetrated by vacuum saturation method counts about 50% of the total voids.

An improved method for permeability estimation of the bioclastic limestone reservoir based on NMR data.

Science.gov (United States)

Ge, Xinmin; Fan, Yiren; Liu, Jianyu; Zhang, Li; Han, Yujiao; Xing, Donghui

2017-10-01

Permeability is an important parameter in formation evaluation since it controls the fluid transportation of porous rocks. However, it is challengeable to compute the permeability of bioclastic limestone reservoirs by conventional methods linking petrophysical and geophysical data, due to the complex pore distributions. A new method is presented to estimate the permeability based on laboratory and downhole nuclear magnetic resonance (NMR) measurements. We divide the pore space into four intervals by the inflection points between the pore radius and the transversal relaxation time. Relationships between permeability and percentages of different pore intervals are investigated to investigate influential factors on the fluid transportation. Furthermore, an empirical model, which takes into account of the pore size distributions, is presented to compute the permeability. 212 core samples in our case show that the accuracy of permeability calculation is improved from 0.542 (SDR model), 0.507 (TIM model), 0.455 (conventional porosity-permeability regressions) to 0.803. To enhance the precision of downhole application of the new model, we developed a fluid correction algorithm to construct the water spectrum of in-situ NMR data, aiming to eliminate the influence of oil on the magnetization. The result reveals that permeability is positively correlated with percentages of mega-pores and macro-pores, but negatively correlated with the percentage of micro-pores. Poor correlation is observed between permeability and the percentage of meso-pores. NMR magnetizations and T 2 spectrums after the fluid correction agree well with laboratory results for samples saturated with water. Field application indicates that the improved method provides better performance than conventional models such as Schlumberger-Doll Research equation, Timur-Coates equation, and porosity-permeability regressions. Copyright © 2017 Elsevier Inc. All rights reserved.

Comparing flows to a tunnel for single porosity, double porosity and discrete fracture representations of the EDZ

International Nuclear Information System (INIS)

Hawkins, I.; Swift, B.; Hoch, A.; Wendling, J.

2010-01-01

transfer between the continua. The MINC model is an extension of double continuum models. Double continuum models assume that the flow between the fractures and matrix blocks is 'quasi-steady' (i.e. proportional to the local difference in average pressure between the fractures and matrix blocks). In contrast, the MINC model treats this flow in a fully transient way; it resolves the gradients that drive the flow by discretizing the matrix blocks into a nested sequence of volume elements. DFN models were implemented using the computer program NAPSAC. The program uses an efficient finite-element method that allows the flow through many thousands of fractures to be calculated accurately. Amongst its capabilities, NAPSAC is able to: calculate the effective continuum permeability tensor; calculate the porosity and the inter-fracture matrix block size; simulate steady-state and transient inflows to tunnels; and simulate unsaturated flow in fractured rocks. Continuum models were implemented using the computer program TOUGH2v2. TOUGH2v2 can be used to simulate multiphase flows in single continuum, double continuum or MINC models. A DFN model of the EDZ was developed. The model includes three classes of fractures. - Chevron fractures are curved, flowing surfaces, which cut perpendicular to the tunnel axis and have a variable spacing. - Oblique fractures are planar, and cut into the side of the tunnel at a defined angle. - Random fractures are small, planar features, which lie in a narrow region close to the tunnel wall. - Additionally, lattices of fractures were included in the DFN model to represent the undamaged clay and the concrete lining of the tunnel. NAPSAC was used to calculate effective continuum permeability tensors and porosities for sub-regions of the DFN model. These permeability tensors and porosities were used to parameterize both single continuum and MINC models of the EDZ. For each of the models (i.e. DFN, single continuum and MINC), desaturation of the

Mapping the Fluid Pathways and Permeability Barriers of a Large Gas Hydrate Reservoir

Science.gov (United States)

Campbell, A.; Zhang, Y. L.; Sun, L. F.; Saleh, R.; Pun, W.; Bellefleur, G.; Milkereit, B.

2012-12-01

An understanding of the relationship between the physical properties of gas hydrate saturated sedimentary basins aids in the detection, exploration and monitoring one of the world's upcoming energy resources. A large gas hydrate reservoir is located in the MacKenzie Delta of the Canadian Arctic and geophysical logs from the Mallik test site are available for the gas hydrate stability zone (GHSZ) between depths of approximately 850 m to 1100 m. The geophysical data sets from two neighboring boreholes at the Mallik test site are analyzed. Commonly used porosity logs, as well as nuclear magnetic resonance, compressional and Stoneley wave velocity dispersion logs are used to map zones of elevated and severely reduced porosity and permeability respectively. The lateral continuity of horizontal permeability barriers can be further understood with the aid of surface seismic modeling studies. In this integrated study, the behavior of compressional and Stoneley wave velocity dispersion and surface seismic modeling studies are used to identify the fluid pathways and permeability barriers of the gas hydrate reservoir. The results are compared with known nuclear magnetic resonance-derived permeability values. The aim of investigating this heterogeneous medium is to map the fluid pathways and the associated permeability barriers throughout the gas hydrate stability zone. This provides a framework for an understanding of the long-term dissociation of gas hydrates along vertical and horizontal pathways, and will improve the knowledge pertaining to the production of such a promising energy source.

Effect of W/C Ratio on Durability and Porosity in Cement Mortar with Constant Cement Amount

Directory of Open Access Journals (Sweden)

Yun-Yong Kim

2014-01-01

Full Text Available Water is often added to concrete placing for easy workability and finishability in construction site. The additional mixing water can help easy mixing and workability but causes increased porosity, which yields degradation of durability and structural performances. In this paper, cement mortar samples with 0.45 of W/C (water to cement ratio are prepared for control case and durability performances are evaluated with additional water from 0.45 to 0.60 of W/C. Several durability tests including strength, chloride diffusion, air permeability, saturation, and moisture diffusion are performed, and they are analyzed with changed porosity. The changing ratios and patterns of durability performance are evaluated considering pore size distribution, total porosity, and additional water content.

Integrated Analysis Seismic Inversion and Rockphysics for Determining Secondary Porosity Distribution of Carbonate Reservoir at “FR” Field

Science.gov (United States)

Rosid, M. S.; Augusta, F. F.; Haidar, M. W.

2018-05-01

In general, carbonate secondary pore structure is very complex due to the significant diagenesis process. Therefore, the determination of carbonate secondary pore types is an important factor which is related to study of production. This paper mainly deals not only to figure out the secondary pores types, but also to predict the distribution of the secondary pore types of carbonate reservoir. We apply Differential Effective Medium (DEM) for analyzing pore types of carbonate rocks. The input parameter of DEM inclusion model is fraction of porosity and the output parameters are bulk moduli and shear moduli as a function of porosity, which is used as input parameter for creating Vp and Vs modelling. We also apply seismic post-stack inversion technique that is used to map the pore type distribution from 3D seismic data. Afterward, we create porosity cube which is better to use geostatistical method due to the complexity of carbonate reservoir. Thus, the results of this study might show the secondary porosity distribution of carbonate reservoir at “FR” field. In this case, North – Northwest of study area are dominated by interparticle pores and crack pores. Hence, that area has highest permeability that hydrocarbon can be more accumulated.

Surface-subsurface turbulent interaction at the interface of a permeable bed: influence of the wall permeability

Science.gov (United States)

Kim, T.; Blois, G.; Best, J.; Christensen, K. T.

2017-12-01

Coarse-gravel river beds possess a high degree of permeability. Flow interactions between surface and subsurface flow across the bed interface is key to a number of natural processes occurring in the hyporheic zone. In fact, it is increasingly recognized that these interactions drive mass, momentum and energy transport across the interface, and consequently control biochemical processes as well as stability of sediments. The current study explores the role of the wall permeability in surface and subsurface flow interaction under controlled experimental conditions on a physical model of a gravel bed. The present wall model was constructed by five layers of cubically arranged spheres (d=25.4mm, where d is a diameter) providing 48% of porosity. Surface topography was removed by cutting half of a diameter on the top layer of spheres to render the flow surface smooth and highlight the impact of the permeability on the overlying flow. An impermeable smooth wall was also considered as a baseline of comparison for the permeable wall flow. To obtain basic flow statistics, low-frame-rate high-resolution PIV measurements were performed first in the streamwise-wall-normal (x-y) plane and refractive-index matching was employed to optically access the flow within the permeable wall. Time-resolved PIV experiments in the same facility were followed to investigate the flow interaction across the wall interface in sptaio-temporal domain. In this paper, a detailed analysis of the first and second order velocity statistics as well as the amplitude modulation for the flow overlying the permeable smooth wall will be presented.

Effective porosity and pore-throat sizes of Conasauga Group mudrock: Application, test and evaluation of petrophysical techniques

International Nuclear Information System (INIS)

Dorsch, J.; Katsube, T.J.; Sanford, W.E.; Univ. of Tennessee, Knoxville, TN; Dugan, B.E.; Tourkow, L.M.

1996-04-01

Effective porosity (specifically referring to the interconnected pore space) was recently recognized as being essential in determining the effectiveness and extent of matrix diffusion as a transport mechanism within fractured low-permeability rock formations. The research presented in this report was performed to test the applicability of several petrophysical techniques for the determination of effective porosity of fine-grained siliciclastic rocks. In addition, the aim was to gather quantitative data on the effective porosity of Conasauga Group mudrock from the Oak Ridge Reservation (ORR). The quantitative data reported here include not only effective porosities based on diverse measurement techniques, but also data on the sizes of pore throats and their distribution, and specimen bulk and grain densities. The petrophysical techniques employed include the immersion-saturation method, mercury and helium porosimetry, and the radial diffusion-cell method

Qualitative and Quantitative Characterization of Porosity in a Low Porous and Low Permeable Organic Rich Shale by Combining Broad Ion Beam and Scanning Electron Microscopy (BIB-SEM)

International Nuclear Information System (INIS)

Klaver, Jop; Desbois, Guillaume; Urai, Janos L.

2013-01-01

This contribution focuses on the characterization of porosity in low porous shale using a broad ion beam (BIB) polishing technique combined with a conventional scanning electron microscopy (SEM). Porosity was traced in certain representative elementary areas (REA) and pores detected are segmented from mosaics of secondary electron (SE) images. Traced pores could be classified into two major pore-size classes. Relative large pores (> 0.5 μm 2 ) were found in the organic matter and matrix. They contribute strongly to the overall porosity con-tent of the shale. Nevertheless the far majority of the pores traced have equivalent radius less than 400 nm. Including the latter pore class, the imaged porosity from both samples gives similar results in the order of < 1 %. (authors)

Determination of pore sizes and relative porosity in porous nanoshell architectures using dextran retention with single monomer resolution and proton permeation

Science.gov (United States)

Muhandiramlage, Thusitha P.; Cheng, Zhiliang; Roberts, David L.; Keogh, John P.; Hall, Henry K.; Aspinwall, Craig A.

2012-01-01

Unilamellar phospholipid vesicles prepared using the polymerizable lipid bis-sorbylphosphatidylcholine (bis-SorbPC) yield three-dimensional nanoarchitectures that are highly permeable to small molecules. The resulting porous phospholipid nanoshells (PPNs) are potentially useful for a range of biomedical applications including nanosensors and nanodelivery vehicles for cellular assays and manipulations. The uniformity and size distribution of the pores, key properties for sensor design and utilization, has not previously been reported. Fluorophore-assisted carbohydrate electrophoresis (FACE) was utilized to assess the nominal molecular weight cutoff limit (NMCL) of the PPN via analysis of retained dextran with single monomer resolution. The NMCL of PPNs prepared from pure bis-SorbPC was equivalent to a 1800 Da linear dextran, corresponding to a maximum pore diameter of 2.6 nm. Further investigation of PPNs prepared using binary mixtures of bis-SorbPC and dioleylphosphatidylcholine (DOPC) revealed a similar NMCL when the bis-SorbPC content exceeded 30 mol %, whereas different size-dependent permeation was observed below this composition. Below 30 mol % bis-SorbPC, dextran retention provided insufficient mass resolution (162 Da) to observe porosity on the experimental time scale; however, proton permeability showed a marked enhancement for bis-SorbPC ≥ 10 mol %. Combined these data suggest that the NMCL for native pores in bis-SorbPC PPNs results from an inherent property within the lipid assembly that can be partially disrupted by dilution of bis-SorbPC below a critical value for domain formation. Additionally, the analytical method described herein should prove useful for the challenging task of elucidating porosity in a range of three-dimensional nanomaterials. PMID:23083108

2.5-D poroelastic wave modelling in double porosity media

Science.gov (United States)

Liu, Xu; Greenhalgh, Stewart; Wang, Yanghua

2011-09-01

To approximate seismic wave propagation in double porosity media, the 2.5-D governing equations of poroelastic waves are developed and numerically solved. The equations are obtained by taking a Fourier transform in the strike or medium-invariant direction over all of the field quantities in the 3-D governing equations. The new memory variables from the Zener model are suggested as a way to represent the sum of the convolution integrals for both the solid particle velocity and the macroscopic fluid flux in the governing equations. By application of the memory equations, the field quantities at every time step need not be stored. However, this approximation allows just two Zener relaxation times to represent the very complex double porosity and dual permeability attenuation mechanism, and thus reduce the difficulty. The 2.5-D governing equations are numerically solved by a time-splitting method for the non-stiff parts and an explicit fourth-order Runge-Kutta method for the time integration and a Fourier pseudospectral staggered-grid for handling the spatial derivative terms. The 2.5-D solution has the advantage of producing a 3-D wavefield (point source) for a 2-D model but is much more computationally efficient than the full 3-D solution. As an illustrative example, we firstly show the computed 2.5-D wavefields in a homogeneous single porosity model for which we reformulated an analytic solution. Results for a two-layer, water-saturated double porosity model and a laterally heterogeneous double porosity structure are also presented.

Use of geophysical logs to estimate the quality of ground water and the permeability of aquifers

Science.gov (United States)

Hudson, J.D.

1996-01-01

The relation of formation factor to resistivity of formation water and intergranular permeability has often been investigated, and the general consensus is that this relation is closest when established in a clean-sand aquifer in which water quality does not vary substantially. When these restrictions are applied, the following standard equation is a useful tool in estimating the resistance of the formation water: F = Ro/Rw, where F is the formation factor, which is a function of the effective porosity; Ro is the resistivity of a formation that is 100 percent saturated with interstitial water; and Rw is the resistivity of the water in the saturated zone. However, arenaceous aquifers can have electrical resistivities that are not directly related to resistivity of water or porosity. Surface conductivity and ion exchange are significant factors when the sediments are clay bearing. The solid constituents are a major component of the parameters needed to solve the equation for formation-water resistivity and estimates of aquifer permeability. A correction process needs to be applied to adjust the variables, Ro and F, to the equivalent of clean sand. This report presents an empirical method of using the neutron log and the electrical-resistivity values from long- and short-normal resistivity logs to correct for fine-grained material and the subsequent effects of low impedance to electrical flow that are not related to the resistance of formation water.

Zeolites with Continuously Tuneable Porosity**

Science.gov (United States)

Wheatley, Paul S; Chlubná-Eliášová, Pavla; Greer, Heather; Zhou, Wuzong; Seymour, Valerie R; Dawson, Daniel M; Ashbrook, Sharon E; Pinar, Ana B; McCusker, Lynne B; Opanasenko, Maksym; Čejka, Jiří; Morris, Russell E

2014-01-01

Zeolites are important materials whose utility in industry depends on the nature of their porous structure. Control over microporosity is therefore a vitally important target. Unfortunately, traditional methods for controlling porosity, in particular the use of organic structure-directing agents, are relatively coarse and provide almost no opportunity to tune the porosity as required. Here we show how zeolites with a continuously tuneable surface area and micropore volume over a wide range can be prepared. This means that a particular surface area or micropore volume can be precisely tuned. The range of porosity we can target covers the whole range of useful zeolite porosity: from small pores consisting of 8-rings all the way to extra-large pores consisting of 14-rings. PMID:25284344

Estimation of relative permeability and capillary pressure from mass imbibition experiments

Science.gov (United States)

Alyafei, Nayef; Blunt, Martin J.

2018-05-01

We perform spontaneous imbibition experiments on three carbonates - Estaillades, Ketton, and Portland - which are three quarry limestones that have very different pore structures and span wide range of permeability. We measure the mass of water imbibed in air saturated cores as a function of time under strongly water-wet conditions. Specifically, we perform co-current spontaneous experiments using a highly sensitive balance to measure the mass imbibed as a function of time for the three rocks. We use cores measuring 37 mm in diameter and three lengths of approximately 76 mm, 204 mm, and 290 mm. We show that the amount imbibed scales as the square root of time and find the parameter C, where the volume imbibed per unit cross-sectional area at time t is Ct1/2. We find higher C values for higher permeability rocks. Employing semi-analytical solutions for one-dimensional flow and using reasonable estimates of relative permeability and capillary pressure, we can match the experimental data. We finally discuss how, in combination with conventional measurements, we can use theoretical solutions and imbibition measurements to find or constrain relative permeability and capillary pressure.

Predicting Porosity and Permeability for the Canyon Formation, SACROC Unit (Kelly-Snyder Field), Using the Geologic Analysis via Maximum Likelihood System

International Nuclear Information System (INIS)

Reinaldo Gonzalez; Scott R. Reeves; Eric Eslinger

2007-01-01

-based, probabilistic clustering analysis procedure is successfully applied to generate a high-resolution reservoir characterization outcome. The approach was applied in the Pennsylvanian-Permian reef carbonates (Cisco and Canyon Formations) of a subregion of the SACROC Unit, Horseshoe Atoll, Permian Basin, Texas, and acknowledged as a highly complex carbonate reservoir. Due to the modest results achieved with the application of soft-computing methodologies to the available information (no crosswell data at hand), the original project target about creating a data-driven device relating surface seismic information, crosswell seismic attributes, geophysical logs and core parameters for the prediction of core-scale porosity and permeability profiles in locations where only 3D surface seismic data was available, had to be reformulated. It was shown that 3D seismic information was not capable of capturing the degree of vertical variability of SACROC. As a consequence, available seismic information was unincorporated from posterior reservoir characterization tasks, and a combination of data-driven procedures and geostatistical methods was utilized for reservoir characterization purposes. A selected area within the SACROC Unit platform was used for this study. The suitable logs for the creation of an 'intelligent' log-to-core device were not present for all wells. These logs were gamma ray (GR), neutron porosity (NPHI), bulk density (RHOB), and delta time (DT). It was necessary to create a first 'intelligent' tool, a log-to-log model to provide synthetic logs of RHOB and DT (or eventually of acoustic impedance derived from them) at well locations where only GR and NPHI were available (the most common situation in this reservoir). Once the 'ideal' logs were completed, a second model, a log-to-core device, provides core scale estimates of porosity and permeability (P and P). The validity of these soft-computing devices was checked using 'holdout' wells. In this way, 'core' parameter profiles

Pore pressure propagation in a permeable thin-layer coal seam based on a dual porosity model: A case of risk prediction of water inrush in coalmines

Science.gov (United States)

Zhu, B.; Gao, F.; Yang, J. W.; Zhou, G. Q.

2016-08-01

Thin-layer coal seams, a type of filling coal rock body, are considered aquifer systems made up of dual porosity medium with immediate floor. A numerical simulation for the pore pressure propagation along a thin-layer coal seam was carried out for the case of the Zhaogezhuang coalmine in China. By valuing the permeability (Kf ) of the thin-layer coal seam, pore pressure variation with time was simulated and compared to the analytical solutions of a dual porosity model (DPM). The main conclusions were drawn as follow: (1) Seepage in the thin-layer coal seam was predominant in the whole process, and the distance of seepage was lengthened and the pore pressure decreased with increased Kf , (2) A series of simulated hydraulic graphs demonstrated that the pore pressure characteristics of peak-occurring and time-lag effects agreed with the analytical solutions of DPM; (3) By adjusting the parameters of DPM, two results of analytical solutions and numerical solutions fit well, particularly in the thin-layer coal seam, (4) The power law relationship between the peak-values and lag time of pore pressure were derived statistically under consideration of the Kf parameter in the range of 10-8 to 10-10 m2/pa-s orders, and it was reasonable that the Kf of the thin-layer coal seam was in the range of 10-8 m2/pa-s orders. The results were significantly helpful in decision-making for mining water prevention and prediction in practice.

Measurement of relative permeability of fuel cell diffusion media

KAUST Repository

Hussaini, I.S.; Wang, C.Y.

2010-01-01

Gas diffusion layer (GDL) in PEM fuel cells plays a pivotal role in water management. Modeling of liquid water transport through the GDL relies on knowledge of relative permeability functions in the in-plane and through-plane directions

Coupling between cracking and permeability, a model for structure service life prediction

International Nuclear Information System (INIS)

Lasne, M.; Gerard, B.; Breysse, D.

1993-01-01

Many authors have chosen permeability coefficients (permeation, diffusion) as a reference for material durability and for structure service life prediction. When we look for designing engineered barriers for radioactive waste storage we find these macroscopic parameters very essential. In order to work with a predictive model of transfer properties evolution in a porous media (concrete, mortar, rock) we introduce a 'micro-macro' hierarchical model of permeability whose data are the total porosity and the pore size distribution. In spite of the simplicity of the model (very small CPU time consuming) comparative studies show predictive results for sound cement pastes, mortars and concretes. Associated to these works we apply a model of damage due to hydration processes at early ages to a container as a preliminary underproject for the definitive storage of Low Level radioactive Waste (LLW). Data are geometry, cement properties and damage measurement of concrete. This model takes into account the mechanical property of the concrete maturation (volumic variations during cement hydration can damage the structures). Some local microcracking can appear and affect the long term durability. Following these works we introduce our research program for the concrete cracking analysis. An experimental campaign is designed in order to determine damage-cracking-porosity-permeability coupling. (authors). 12 figs., 16 refs

Evaluation of methods for measuring relative permeability of anhydride from the Salado Formation: Sensitivity analysis and data reduction

International Nuclear Information System (INIS)

Christiansen, R.L.; Kalbus, J.S.

1997-05-01

This report documents, demonstrates, evaluates, and provides theoretical justification for methods used to convert experimental data into relative permeability relationships. The report facilities accurate determination of relative permeabilities of anhydride rock samples from the Salado Formation at the Waste Isolation Pilot Plant (WIPP). Relative permeability characteristic curves are necessary for WIPP Performance Assessment (PA) predictions of the potential for flow of waste-generated gas from the repository and brine flow into repository. This report follows Christiansen and Howarth (1995), a comprehensive literature review of methods for measuring relative permeability. It focuses on unsteady-state experiments and describes five methods for obtaining relative permeability relationships from unsteady-state experiments. Unsteady-state experimental methods were recommended for relative permeability measurements of low-permeability anhydrite rock samples form the Salado Formation because these tests produce accurate relative permeability information and take significantly less time to complete than steady-state tests. Five methods for obtaining relative permeability relationships from unsteady-state experiments are described: the Welge method, the Johnson-Bossler-Naumann method, the Jones-Roszelle method, the Ramakrishnan-Cappiello method, and the Hagoort method. A summary, an example of the calculations, and a theoretical justification are provided for each of the five methods. Displacements in porous media are numerically simulated for the calculation examples. The simulated product data were processed using the methods, and the relative permeabilities obtained were compared with those input to the numerical model. A variety of operating conditions were simulated to show sensitivity of production behavior to rock-fluid properties

Permeability of Concrete with Recycled Concrete Aggregate and Pozzolanic Materials under Stress.

Science.gov (United States)

Wang, Hailong; Sun, Xiaoyan; Wang, Junjie; Monteiro, Paulo J M

2016-03-30

The research reported herein studied the permeability of concrete containing recycled-concrete aggregate (RA), superfine phosphorous slag (PHS), and ground granulated blast-furnace slag (GGBS) with and without stress. Test results showed that the chloride diffusion coefficient of RA concrete (RAC) without external loads decreased with time, and the permeability of RAC is much lower than that of the reference concrete due to the on-going hydration and the pozzolanic reaction provided by the PHS and GGBS additives in the RAC mixture. The permeability of chloride under flexural load is much more sensitive than that under compressive load due to the differences in porosity and cracking pattern. At low compressive stress levels, the permeability of chloride decreased by the closing of pores and microcracks within RAC specimens. However, in a relatively short time the chloride diffusion coefficient and the chloride content increased rapidly with the increase of compressive stress when it exceeded a threshold stress level of approximate 35% of the ultimate compressive strength. Under flexural stress, the chloride transport capability increased with the increase of stress level and time. At high compressive and flexural stress levels, creep had a significant effect on the permeability of chloride in the RAC specimens due to the damage from the nucleation and propagation of microcracks over time. It is apparent that mortar cracking has more of a significant effect on the chloride transport in concrete than cracking in the interfacial transition zone (ITZ).

Permeability of Aluminium Foams Produced by Replication Casting

Directory of Open Access Journals (Sweden)

Maxim L. Cherny

2012-12-01

Full Text Available The replication casting process is used for manufacturing open-pore aluminum foams with advanced performances, such as stability and repeatability of foam structure with porosity over 60%. A simple foam structure model based on the interaction between sodium chloride solid particles poorly wetted by melted aluminum, which leads to the formation of air pockets (or “air collars”, is proposed for the permeability of porous material. The equation for the minimum pore radius of replicated aluminum foam is derived. According to the proposed model, the main assumption of the permeability model consists in a concentration of flow resistance in a circular aperture of radius rmin. The permeability of aluminum open-pore foams is measured using transformer oil as the fluid, changing the fractions of initial sodium chloride. Measured values of minimum pore size are close to theoretically predicted ones regardless of the particle shape. The expression for the permeability of replicated aluminum foam derived on the basis of the “bottleneck” model of porous media agrees well with the experimental data. The obtained data can be applied for commercial filter cells and pneumatic silencers.

Field-scale permeability and temperature of volcanic crust from borehole data: Campi Flegrei, southern Italy

Science.gov (United States)

Carlino, Stefano; Piochi, Monica; Tramelli, Anna; Mormone, Angela; Montanaro, Cristian; Scheu, Bettina; Klaus, Mayer

2018-05-01

We report combined measurements of petrophysical and geophysical parameters for a 501-m deep borehole located on the eastern side of the active Campi Flegrei caldera (Southern Italy), namely (i) in situ permeability by pumping tests, (ii) laboratory-determined permeability of the drill core, and (iii) thermal gradients by distributed fiber optic and thermocouple sensors. The borehole was drilled during the Campi Flegrei Deep Drilling Project (in the framework of the International Continental Scientific Drilling Program) and gives information on the least explored caldera sector down to pre-caldera deposits. The results allow comparative assessment of permeability obtained from both borehole (at depth between 422 a 501 m) and laboratory tests (on a core sampled at the same depth) for permeability values of 10-13 m2 (borehole test) and 10-15 m2 (laboratory test) confirm the scale-dependency of permeability at this site. Additional geochemical and petrophysical determinations (porosity, density, chemistry, mineralogy and texture), together with gas flow measurements, corroborate the hypothesis that discrepancies in the permeability values are likely related to in-situ fracturing. The continuous distributed temperature profile points to a thermal gradient of about 200 °C km-1. Our findings (i) indicate that scale-dependency of permeability has to be carefully considered in modelling of the hydrothermal system at Campi Flegrei, and (ii) improve the understanding of caldera dynamics for monitoring and mitigation of this very high volcanic risk area.

Rapid increases in permeability and porosity of bentonite-sand mixtures due to alteration by water vapor

International Nuclear Information System (INIS)

Couture, R.A.

1984-01-01

Packed columns of canister packing material containing 25% bentonite and 75% quartz or basalt sand, were exposed to water vapor at temperatures up t 260 0 C. The permeabilities of the columns were subsequently measured after complete saturation with liquid water in a pressurized system. Exposure to water vapor caused irreversible increases in permeability by factors of up to 10 5 . After saturation with liquid water, the permeability was nearly independent of temperature. The increases in permeability were due to a large decrease in the ability of the bentonite to swell in water. Calculations suggest that swelling of bentonite altered at 250 0 C was not sufficient to fill the pore spaces. If the pore spaces are filled, the mixture will form an effective barrier against flow, diffusion, and transport of colloids. The results suggest that if bentonite-based canister packing material is exposed even briefly to water vapor at high temperatures in a high-level nuclear waste repository, its performance will be seriously impaired. The problem is less severe if the proportion of bentonite is high and the material is highly compacted. Previous results show significant degradation of bentonite by water vapor at temperatures as low as 150 0 C. This suggests that in some repositories, backfill in tunnels and drifts may also be affected. 9 references, 5 figures, 1 table

Earth formation porosity log

International Nuclear Information System (INIS)

Smith, H.D.; Smith, M.P.; Schultz, W.E.

1977-01-01

A method for determining the porosity of earth formations in the vicinity of a cased well borehole is described, comprising the steps of: irradiating the earth formations in the vicinity of the cased well borehole with fast neutrons from a source of fast neutrons passed into the borehole; and generating a signal representative of the fast neutron population present in the well borehole at a location in the borehole, the signal is functionally related to the porosity of the earth formations in the vicinity of the borehole

Preparation and microstructure of ZrO2- and LaGaO3-based high-porosity ceramics

International Nuclear Information System (INIS)

Kaleva, G.M.; Golubko, N.V.; Suvorkin, S.V.; Kosarev, G.V.; Sukhareva, I.P.; Avetisov, A.K.; Politova, E.D.

2006-01-01

The morphology and concentration of pore formers are studied for their effect on the microstructure and gas permeability of porous zirconia- and lanthanum-gallate-based oxygen-ion-conducting ceramics. The results have been used to optimize the preparation conditions and composition of the ceramics. The resultant dense, fine-grained materials have porosities of up to ∼56% [ru

Plant fibre composites - porosity and volumetric interaction

DEFF Research Database (Denmark)

Madsen, Bo; Thygesen, Anders; Lilholt, Hans

2007-01-01

the combination of a high fibre volume fraction, a low porosity and a high composite density is optimal. Experimental data from the literature on volumetric composition and density of four types of plant fibre composites are used to validate the model. It is demonstrated that the model provides a concept......Plant fibre composites contain typically a relative large amount of porosity, which considerably influences properties and performance of the composites. The large porosity must be integrated in the conversion of weight fractions into volume fractions of the fibre and matrix parts. A model...... is presented to predict the porosity as a function of the fibre weight fractions, and to calculate the related fibre and matrix volume fractions, as well as the density of the composite. The model predicts two cases of composite volumetric interaction separated by a transition fibre weight fraction, at which...

Fluid flow pathways through the oceanic crust: reaction permeability and isotopic tracing

Science.gov (United States)

McCaig, Andrew; Castelain, Teddy; Klein, Frieder

2013-04-01

It is generally assumed that the dominant means of creating permeability in ocean floor hydrothermal systems is fracturing, induced either by cooling or by tectonic stress. Here we show textural evidence that metamorphic reactions can create a hierarchy of permeable pathways through gabbroic rocks similar to a fracture hierarchy. Isotopic microsampling shows that just as with fractures, most flow occurs through the larger channelways, and that even at the microscale, flow can be extremely heterogeneous with alteration affecting only certain minerals in the framework, leaving others untouched. Reaction permeability is created in three ways; dissolution creating open porosity, microcracking due to volume increase reactions involving olivine, and expansion of water due to rapid heating in dyke margins, particularly when intruded into brecciated rocks. Our data comes from IODP Hole U1309D, which was drilled to 1400 mbsf in the footwall of the Atlantis Massif detachment fault at the Mid-Atlantic Ridge 30°N. The core is composed of gabbroic rocks interlayered with olivine rich troctolites, with several basalt/diabase sills in the top 130 m. The dominant alteration occurred in the greenschist facies, at depths at least 1 km below seafloor, and decreases in intensity downhole. Whole rock oxygen isotope values range from +5.5 permil to +1.5 permil, indicating variable degrees of interaction with seawater at temperatures generally > 250 °C. Gabbroic rocks and diabases exhibit a range of Sr isotope ratios from MORB values (0.70261) to intermediate ratios (0.70429). Microsampling shows that amphiboles are often more radiogenic than coexisting plagioclase and can sometimes be isotopically altered in the same rock as completely unaltered primary minerals. Large (10 cm) amphibole-filled vugs show values ranging up to 0.708, close to seawater. In some cases however the secondary minerals are virtually unaltered indicating low fluid fluxes in pervasive alteration. SEM textures in

A comparison of experimental methods for measuring water permeability of porous building rocks

Directory of Open Access Journals (Sweden)

Galvan, S.

2014-09-01

Full Text Available This paper compares different experimental methods for measuring water permeability in 17 different porous building rocks. Both commercial apparatus and specially made designed permeameters are used for characterising intrinsic permeability and hydraulic conductivity, k, of rocks in the range of 10−12 to 10−4 m/s (~ 10−19−10−11 m2 or ~ 10−4−104 mD. We use both falling head and constant head permeameter methods including the triaxial and modified triaxial tests and a classical constant head permeameter. Results showed that for very low and low permeability samples (k−6 m/s, triaxial conditions were found the most accurate procedures and they provided similar or slightly lower permeability values than constant and falling head methods. The latter techniques were highly recommended for permeable and high permeable porous building materials. Water permeability values were also linked to effective porosity and interpreted in terms of interparticle and vugs porosity. Finally, some modifications in the apparatus and procedures were carried out in order to assess water permeability in soft materials, which involve the use of non-saturated samples.Se comparan diferentes métodos experimentales para la medida de la permeabilidad al agua en rocas porosas usadas como material de construcción. Se usaron diferentes permeabilímetros, (comerciales y desarrollados específicamente empleando los métodos triaxial, triaxial modificado, carga constante y carga variable. Se caracterizó la permeabilidad intrínseca y conductividad hidráulica, k, con valores que var.an desde 10−12 a 10−4 m/s (~ 10−19−10−11 m2 or ~ 10−4−104 mD. Para muestras poco y muy poco permeables el ensayo con célula triaxial fue el mas reproducible. Los ensayos de carga constante son muy recomendables para rocas porosas de construcción permeables y muy permeables. Además, se definen los parámetros experimentales más apropiados para caracterizar la

Self-Assembling Sup-porosity: The Effect On Fluid Flow And Seismic Wave Propagation

Energy Technology Data Exchange (ETDEWEB)

Pyrak-Nolte, Laura J. [Purdue University

2013-04-27

Fractures and joints in the field often contain debris within the void spaces. Debris originates from many different mechanisms: organic and/or inorganic chemical reactions/mineralization, sediment transport, formation of a fracture, mechanical weathering or combinations of these processes. In many cases, the presence of debris forms a sub-porosity within the fracture void space. This sub-porosity often is composed of material that differs from the fracture walls in mineralogy and morphology. The sub-porosity may partially fill voids that are on the order of hundreds of microns and thereby reduce the local porosity to lengths scales on the order of sub-microns to tens of microns. It is quite clear that a sub-porosity affects fracture porosity, permeability and storativity. What is not known is how the existence/formation of a sub-porosity affects seismic wave propagation and consequently our ability to probe changes in the subsurface caused by the formation or alteration of a sub-porosity. If seismic techniques are to be developed to monitor the injection and containment of phases in sequestration reservoirs or the propping of hydraulically induced fracture to enhance oil & gas production, it is important to understand how a sub-porosity within a fracture affects macroscopic seismic and hydraulic measurements. A sub-porosity will directly affect the interrelationship between the seismic and hydraulic properties of a fracture. This reports contains the results of the three main topics of research that were performed (1) to determine the effect of a sub-porosity composed of spherical grains on seismic wave propagation across fractures, (2) to determine the effect of biofilm growth in pores and between grains on seismic wave propagation in sediment, and (3) to determine the effect of the scale of observation (field-of-view) on monitoring alteration the pore space within a fracture caused by reactive flow. A brief summary of the results for each topic is contained in

Zeolites with continuously tuneable porosity

OpenAIRE

Wheatley, Paul S; Chlubná-Eliášová, Pavla; Greer, Heather; Zhou, Wuzong; Seymour, Valerie R; Dawson, Daniel M; Ashbrook, Sharon E; Pinar, Ana B; McCusker, Lynne B; Opanasenko, Maksym; Cejka, Jiří; Morris, Russell E

2014-01-01

Czech Science Foundation. Grant Number: P106/12/G015 Zeolites are important materials whose utility in industry depends on the nature of their porous structure. Control over microporosity is therefore a vitally important target. Unfortunately, traditional methods for controlling porosity, in particular the use of organic structure-directing agents, are relatively coarse and provide almost no opportunity to tune the porosity as required. Here we show how zeolites with a continuously tuneabl...

Instability of an infiltration-driven dissolution-precipitation front with a nonmonotonic porosity profile

Science.gov (United States)

Kondratiuk, Paweł; Dutka, Filip; Szymczak, Piotr

2016-04-01

Infiltration of a rock by an external fluid very often drives it out of chemical equilibrium. As a result, alteration of the rock mineral composition occurs. It does not however proceed uniformly in the entire rock volume. Instead, one or more reaction fronts are formed, which are zones of increased chemical activity, separating the altered (product) rock from the yet unaltered (primary) one. The reaction fronts propagate with velocities which are usually much smaller than those of the infiltrating fluid. One of the simplest examples of such alteration is the dissolution of some of the minerals building the primary rock. For instance, calcium carbonate minerals in the rock matrix can be dissolved by infiltrating acidic fluids. In such a case the product rock has higher porosity and permeability than the primary one. Due to positive feedbacks between the reactant transport, fluid flow, and porosity generation, the reaction fronts in porosity-generating replacement systems are inherently unstable. An arbitrarily small protrusion of the front gets magnified and develops into a highly porous finger-like or funnel-like structure. This feature of dissolution fronts, dubbed the "reactive-infiltration instability" [1], is responsible for the formation of a number of geological patterns, such as solution pipes or various karst forms. It is also of practical importance, since spontaneous front breakup and development of localized highly porous flow paths (a.k.a. "wormholes") is favourable by petroleum engineers, who apply acidization to oil-bearing reservoirs in order to increase their permeability. However, more complex chemical reactions might occur during infiltration of a rock by a fluid. In principle, the products of dissolution might react with other species present either in the fluid or in the rock and reprecipitate [2]. The dissolution and precipitation fronts develop and and begin to propagate with equal velocities, forming a single dissolution-precipitation front

A multiscale model of distributed fracture and permeability in solids in all-round compression

Science.gov (United States)

De Bellis, Maria Laura; Della Vecchia, Gabriele; Ortiz, Michael; Pandolfi, Anna

2017-07-01

We present a microstructural model of permeability in fractured solids, where the fractures are described in terms of recursive families of parallel, equidistant cohesive faults. Faults originate upon the attainment of tensile or shear strength in the undamaged material. Secondary faults may form in a hierarchical organization, creating a complex network of connected fractures that modify the permeability of the solid. The undamaged solid may possess initial porosity and permeability. The particular geometry of the superposed micro-faults lends itself to an explicit analytical quantification of the porosity and permeability of the damaged material. The model is the finite kinematics version of a recently proposed porous material model, applied with success to the simulation of laboratory tests and excavation problems [De Bellis, M. L., Della Vecchia, G., Ortiz, M., Pandolfi, A., 2016. A linearized porous brittle damage material model with distributed frictional-cohesive faults. Engineering Geology 215, 10-24. Cited By 0. 10.1016/j.enggeo.2016.10.010]. The extension adds over and above the linearized kinematics version for problems characterized by large deformations localized in narrow zones, while the remainder of the solid undergoes small deformations, as typically observed in soil and rock mechanics problems. The approach is particularly appealing as a means of modeling a wide scope of engineering problems, ranging from the prevention of water or gas outburst into underground mines, to the prediction of the integrity of reservoirs for CO2 sequestration or hazardous waste storage, to hydraulic fracturing processes.

Lattice Boltzmann simulations of the permeability and capillary adsorption of cement model microstructures

Energy Technology Data Exchange (ETDEWEB)

Zalzale, M. [Laboratory of Construction Materials, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); McDonald, P.J., E-mail: p.mcdonald@surrey.ac.uk [Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)

2012-12-15

The lattice Boltzmann method is used to investigate the permeability of microstructures of cement pastes generated using the numerical models CEMHYD3D (Bentz, 1997) and {mu}IC (Bishnoi and Scrivener, 2009). Results are reported as a function of paste water-to-cement ratio and degree of hydration. The permeability decreases with increasing hydration and decreasing water-to-cement ratio in agreement with experiment. However the permeability is larger than the experimental data recorded using beam bending methods (Vichit-Vadakan and Scherer, 2002). Notwithstanding, the lattice Boltzmann results compare favourably with alternate numerical methods of permeability calculation for cement model microstructures. In addition, we show early results for the liquid/vapour capillary adsorption and desorption isotherms in the same model {mu}IC structures. The broad features of the experimental capillary porosity isotherm are reproduced, although further work is required to adequately parameterise the model.

Relative permeability of the endothelium and epithelium of rabbit lungs

International Nuclear Information System (INIS)

Effros, R.M.; Mason, G.R.; Silverman, P.; Hukkanen, J.

1986-01-01

Electron micrographic studies of lungs suggest that the epithelial cells are more tightly joined than the underlying endothelium, and macromolecules penetrate the endothelium more readily than the epithelium. Comparisons of epithelial and endothelial permeability to small molecules have been based upon the relative rates at which solutes traverse the alveolar-capillary barrier in fluid filled lungs and those at which they equilibrate across the capillaries in air-filled lungs. Because the former process is much slower than the latter, it has been concluded that the epithelium is less permeable to small solutes than the endothelium. However this difference may be related to inadequate access of solutes to airway surfaces. In this study, solute losses from the vascular space were compared to those from the airspace in perfused, fluid-filled rabbit lungs. 36 Cl - and 125 I - were lost from air-spaces almost twice as rapidly as 22 Na + . In contrast, the endothelium is equally permeable to 22 Na + and these anions. Loss of 3 H-mannitol from the perfusate resembled that of 22 Na + for about 30 minutes, after which diffusion of 3 H-mannitol into the tissue nearly ceased. These observations suggest that the epithelium is more permselective than the endothelium. By resisting solute and water transport, the epithelium tends to prevent alveolar flooding and confines edema to the interstitium, where it is less likely to interfere with gas exchange

Remaining porosity and permeability of compacted crushed rock salt backfill in a HLW repository. Final report

Energy Technology Data Exchange (ETDEWEB)

Jobmann, M.; Mueller, C.; Schirmer, S.

2015-11-15

The safe containment of radioactive waste is to be ensured by the geotechnical barriers in combination with the containment-providing rock zone (CRZ). The latter is a key element of the recently developed concept of demonstrating the integrity of the geologic barrier (Krone et al., 2013). As stipulated in the safety requirements of the regulating body the CRZ has to have strong barrier properties, and evidence needs to be provided that it retains its integrity throughout the reference period (BMU, 2010). The underground openings excavated in the rock salt will close over time due to the creep properties of the rock salt. This process causes deformations in the surrounding rock salt, which leads to a change in stress state in the virgin rock and may impair the integrity of the containment-providing rock zone. In order to limit the effects of these processes, all underground openings will be backfilled with crushed salt. Immediately after backfilling, the crushed salt will have an initial porosity of approx. 35%, which - over time - will be reduced to very low values due to the creep properties of the rock salt. The supporting pressure that builds up in the crushed salt with increasing compaction slows down the creeping of the salt. Major influencing factors are the temperature (with higher temperatures accelerating the salt creeping) and the moisture of the salt, which - due to the related decrease in the resistance of the crushed salt - facilitates its compaction. The phenomenology of these processes and dependencies is understood to a wide extent. This project investigated the duration until compaction is completed and when and under what circumstances the crushed salt will have the sealing properties necessary to ensure safe containment. Thermo-hydro-mechanical (THM) processes play a crucial role in determining whether solutions which might enter the mine could reach the radioactive waste. This includes changes in material behaviour due to a partial or complete

Thermally induced permeability reduction due to particle migration in sandstones: the effect of temperature on kaolinite mobilisation and aggregation

DEFF Research Database (Denmark)

Rosenbrand, Esther; Fabricius, Ida Lykke; Yuan, Hao

2012-01-01

The seasonal imbalance in supply and demand of renewable energy requires seasonal storage, which potentially may be achieved by hot water injection in geothermal aquifers to minimize heat loss by advection. A reduction of porosity and permeability is a risk of heating the rock above the in...... the interaction energy between quartz and kaolinite particles for different saturating fluids. The results are compared to the published data addressing the effect of temperature on permeability. This provides a qualitative explanation for the observed changes in permeability with temperature for the tests...

The permeability evolution of tuffisites and outgassing from dense rhyolitic magma

Science.gov (United States)

Heap, M. J.; Tuffen, H.; Wadsworth, F. B.; Reuschlé, T.; Castro, J. M.; Schipper, C. I.

2017-12-01

Recent observations of rhyolitic lava effusion from eruptions in Chile indicate that simultaneous pyroclastic venting facilitates outgassing. Venting from conduit-plugging lava domes is pulsatory and occurs through shallow fracture networks that deliver pyroclastic debris and exsolved gases to the surface. However, these fractures become blocked as the particulate fracture infill sinters viscously, thus drastically reducing permeability. Tuffisites, fossilized debris-filled fractures of this venting process, are abundant in pyroclastic material ejected during hybrid explosive-effusive activity. Dense tuffisite-hosting obsidian bombs ejected from Volcán Chaitén (Chile) in 2008 afford an opportunity to better understand the permeability evolution of tuffisites within low-permeability conduit plugs, wherein gas mobility is reliant upon fracture pathways. We use laboratory measurements of the permeability and porosity of tuffisites that preserve different degrees of sintering, combined with a grainsize-based sintering model and constraints on pressure-time paths from H2O diffusion, to place first-order constraints on tuffisite permeability evolution. Inferred timescales of sintering-driven tuffisite compaction and permeability loss, spanning minutes to hours, coincide with observed vent pulsations during hybrid rhyolitic activity and, more broadly, timescales of pressurization accompanying silicic lava dome extrusion. We therefore conclude that sintering exerts a first-order control on fracture-assisted outgassing from low-permeability, conduit-plugging silicic magma.

Acamprosate permeability across Caco-2 cell monolayer is predominantly paracellular

DEFF Research Database (Denmark)

Antonescu, Irina-Elena; Steffansen, Bente

support area, thickness, and porosity). Results. The mean (± SD) Papp, exp of acamprosate and [14C]-mannitol across Caco-2 cell monolayers was measured as 0.19 ± 0.07 x 10-6 cm/s (n = 2, N = 3) and 0.35 ± 0.17 x 10-6 cm/s (n = 3, N = 4), respectively. Acamprosate PUBL and Pf were estimated as 200 - 3150 x...... role in acamprosate permeability, as only a very low fraction of acamprosate is in the neutral form at pH 7.4. The estimated acamprosate Ppara accounts for nearly 100% of the mathematically determined acamprosate Papp, calc (0.20 ± 0.10 x 10-6 cm/s), which matches well with the experimentally...... to the overall acamprosate apparent permeability. Methods. Acamprosate apparent permeability (Papp, exp) was determined across Caco-2 monolayers in the apical-to-basolateral transport direction using a buffer pH of 7.4 and several cell passages (N). Acamprosate concentrations were quantified by LC...

Characterization of fracture reservoirs using static and dynamic data: From sonic and 3D seismic to permeability distribution. Annual report, March 1, 1996--February 28, 1997

Energy Technology Data Exchange (ETDEWEB)

Parra, J.O.; Collier, H.A.; Owen, T.E. [and others

1997-06-01

In low porosity, low permeability zones, natural fractures are the primary source of permeability which affect both production and injection of fluids. The open fractures do not contribute much to porosity, but they provide an increased drainage network to any porosity. They also may connect the borehole to remote zones of better reservoir characteristics. An important approach to characterizing the fracture orientation and fracture permeability of reservoir formations is one based on the effects of such conditions on the propagation of acoustic and seismic waves in the rock. The project is a study directed toward the evaluation of acoustic logging and 3D-seismic measurement techniques as well as fluid flow and transport methods for mapping permeability anisotropy and other petrophysical parameters for the understanding of the reservoir fracture systems and associated fluid dynamics. The principal application of these measurement techniques and methods is to identify and investigate the propagation characteristics of acoustic and seismic waves in the Twin Creek hydrocarbon reservoir owned by Union Pacific Resources (UPR) and to characterize the fracture permeability distribution using production data. This site is located in the overthrust area of Utah and Wyoming. UPR drilled six horizontal wells, and presently UPR has two rigs running with many established drill hole locations. In addition, there are numerous vertical wells that exist in the area as well as 3D seismic surveys. Each horizontal well contains full FMS logs and MWD logs, gamma logs, etc.

Numerical analysis of the impact of permeability on trailing-edge noise

Science.gov (United States)

Koh, Seong Ryong; Meinke, Matthias; Schröder, Wolfgang

2018-05-01

The impact of porous surfaces on the near-wall turbulent structures and the generated trailing-edge noise is analyzed for several trailing-edge shapes of finite thickness using a high resolution large-eddy simulation (LES)/computational aeroacoustics (CAA) method. The porous surface of the trailing edge is defined by the porosity and the viscous permeability determined by the solution of a turbulent flat plate boundary layer at a Reynolds number 1280 based on the displacement thickness in the inflow cross section. The volume-averaged approach for the homogeneous porous medium shows that the porous impedance scales linearly with the porosity and exponentially with the mean structure size of a porous medium. The drag induced by the porous surface changes the friction velocity and the permeability Reynolds number ReK which determines the porous impedance Rs scaled by ReK-2/3. The trailing-edge noise is analyzed for three solid and three porous trailing edges. The effect of a finite span is investigated by the spanwise correlation model based on the measured coherence distribution. The acoustic prediction shows a good agreement with measurements of the broadband spectrum and the strong tone generated by a finite trailing-edge thickness. The pressure gradient inside the porous media is redistributed by the Darcy drag defined by the viscous permeability and the porosity. The mean pressure increases in the upstream direction inside the porous medium such that the flow acceleration involved in the acoustic generation is reduced inside the porous medium. The noise reduction by a porous medium reaches 11 dB for the trailing-edge shape which possesses a sharp corner for the solid surface. The porous surface applied to a semi-circular trailing edge achieves a 4 dB noise reduction. The directivity pattern for individual components of the acoustic spectrum shows that the massive noise reduction is determined at the tone. Enhanced wave diffraction by the thick flat plate changes

2D and 3D imaging resolution trade-offs in quantifying pore throats for prediction of permeability

Energy Technology Data Exchange (ETDEWEB)

Beckingham, Lauren E.; Peters, Catherine A.; Um, Wooyong; Jones, Keith W.; Lindquist, W.Brent

2013-09-03

Although the impact of subsurface geochemical reactions on porosity is relatively well understood, changes in permeability remain difficult to estimate. In this work, pore-network modeling was used to predict permeability based on pore- and pore-throat size distributions determined from analysis of 2D scanning electron microscopy (SEM) images of thin sections and 3D X-ray computed microtomography (CMT) data. The analyzed specimens were a Viking sandstone sample from the Alberta sedimentary basin and an experimental column of reacted Hanford sediments. For the column, a decrease in permeability due to mineral precipitation was estimated, but the permeability estimates were dependent on imaging technique and resolution. X-ray CT imaging has the advantage of reconstructing a 3D pore network while 2D SEM imaging can easily analyze sub-grain and intragranular variations in mineralogy. Pore network models informed by analyses of 2D and 3D images at comparable resolutions produced permeability esti- mates with relatively good agreement. Large discrepancies in predicted permeabilities resulted from small variations in image resolution. Images with resolutions 0.4 to 4 lm predicted permeabilities differ- ing by orders of magnitude. While lower-resolution scans can analyze larger specimens, small pore throats may be missed due to resolution limitations, which in turn overestimates permeability in a pore-network model in which pore-to-pore conductances are statistically assigned. Conversely, high-res- olution scans are capable of capturing small pore throats, but if they are not actually flow-conducting predicted permeabilities will be below expected values. In addition, permeability is underestimated due to misinterpreting surface-roughness features as small pore throats. Comparison of permeability pre- dictions with expected and measured permeability values showed that the largest discrepancies resulted from the highest resolution images and the best predictions of

Contributions to the study of porosity in fly ash-based geopolymers. Relationship between degree of reaction, porosity and compressive strength

Directory of Open Access Journals (Sweden)

Y. Luna-Galiano

2016-09-01

Full Text Available The main contribution of this paper relates to the development of a systematic study involving a set of parameters which could potentially have an impact on geopolymer properties: curing temperature, type of activating solution, alkali metal in solution, incorporation of slag (Ca source and type of slag used. The microstructures, degrees of reaction, porosities and compressive strengths of geopolymers have been evaluated. Geopolymers prepared with soluble silicate presented a more compacted and closed structure, a larger amount of gel, lower porosity and greater compressive strength than those prepared with hydroxides. On the other hand, Na-geopolymers were more porous but more resistant than K-geopolymers. Although there is an inverse relation between degree of reaction and porosity, between compressive strength and porosity it is not always inversely proportional and could, in some cases, be masked by changes produced in other influencing parameters.

Study of pressure drop, void fraction and relative permeabilities of two phase flow through porous media

International Nuclear Information System (INIS)

Chu, W.; Dhir, V.K.; Marshall, J.

1983-01-01

An experimental investigation of two phase flow through porous layers formed of non-heated glass particles (nominal diameter 1 to 6 mm) has been made. Particulate bed depths of 30 cm and 70 cm were used. The effect of particle size, particle size distribution and bed porosity on void fraction and pressure drop through a particulate bed formed in a cylindrical test section has been investigated. The superficial velocity of liquid (water) is varied from 1.83 to 18.3 mm/s while the superficial velocity of gas (air) is varied from 0 to 68.4 mm/s. These superficial velocities were chosen so that pressure drop and void fraction measurement could be made for the porous layer in fixed and fluidized states. A model based on drift flux approach has been developed for the void fraction. Using the two phase friction pressure drop data, the relative permeabilities of the two phases have been concluded with void fraction. The void fraction and two phase friction pressure gradient in beds composed of mixtures of spherical particles as well as sharps of different nominal sizes have also been examined. It is found that the models for single size particles are also applicable to mixtures of particles if a mean particle diameter for the mixture is defined

Predicting carbonate permeabilities from wireline logs using a back-propagation neural network

International Nuclear Information System (INIS)

Wiener, J.M.; Moll, R.F.; Rogers, J.A.

1991-01-01

This paper explores the applicability of using Neural Networks to aid in the determination of carbonate permeability from wireline logs. Resistivity, interval transit time, neutron porosity, and bulk density logs form Texaco's Stockyard Creek Oil field were used as input to a specially designed neural network to predict core permeabilities in this carbonate reservoir. Also of interest was the comparison of the neural network's results to those of standard statistical techniques. The process of developing the neural network for this problem has shown that a good understanding of the data is required when creating the training set from which the network learns. This network was trained to learn core permeabilities from raw and transformed log data using a hyperbolic tangent transfer function and a sum of squares global error function. Also, it required two hidden layers to solve this particular problem

Hydrocarbon Potential in Sandstone Reservoir Isolated inside Low Permeability Shale Rock (Case Study: Beruk Field, Central Sumatra Basin)

Science.gov (United States)

Diria, Shidqi A.; Musu, Junita T.; Hasan, Meutia F.; Permono, Widyo; Anwari, Jakson; Purba, Humbang; Rahmi, Shafa; Sadjati, Ory; Sopandi, Iyep; Ruzi, Fadli

2018-03-01

Upper Red Bed, Menggala Formation, Bangko Formation, Bekasap Formation and Duri Formationare considered as the major reservoirs in Central Sumatra Basin (CSB). However, Telisa Formation which is well-known as seal within CSB also has potential as reservoir rock. Field study discovered that lenses and layers which has low to high permeability sandstone enclosed inside low permeability shale of Telisa Formation. This matter is very distinctive and giving a new perspective and information related to the invention of hydrocarbon potential in reservoir sandstone that isolated inside low permeability shale. This study has been conducted by integrating seismic data, well logs, and petrophysical data throughly. Facies and static model are constructed to estimate hydrocarbon potential resource. Facies model shows that Telisa Formation was deposited in deltaic system while the potential reservoir was deposited in distributary mouth bar sandstone but would be discontinued bedding among shale mud-flat. Besides, well log data shows crossover between RHOB and NPHI, indicated that distributary mouth bar sandstone is potentially saturated by hydrocarbon. Target area has permeability ranging from 0.01-1000 mD, whereas porosity varies from 1-30% and water saturation varies from 30-70%. The hydrocarbon resource calculation approximates 36.723 MSTB.

In situ permeability testing of rock salt

International Nuclear Information System (INIS)

Peterson, E.W.; Lagus, P.L.; Broce, R.D.; Lie, K.

1981-04-01

Storage of transuranic (TRU) wastes in bedded salt formations requires a knowledge of the in situ permeability of SENM rock salt. Since assumptions for safety assessments have been made in which these wastes could generate gas pressures on the order of the lithostatic pressure over geologic time scales, the permeability of the surrounding formation becomes an important parameter for determining the manner in which the gases will be contained or dispersed. This report describes the series of tests conducted in the AEC-7 borehole, located near the WIPP site, to determine the in situ gas flow characteristics of the bedded salt. In these tests, compressed air was injected into the borehole and flow into the surrounding formation measured. These measured flow rates were interpreted in terms of formation permeabilities and porosities which were, in turn, used as modeling parameters for the repository response analysis. Two series of field tests were performed. The first series consisted of a number of whole-hole flow tests conducted to provide preliminary design information required for future operation of a guarded straddle packer system capable of measuring permeabilities > or = 0.1 μdarcy. The second series of tests were conducted using the Systems, Science and Software (S-Cubed) designed guarded straddle packer system. In these interval permeability tests, 100-foot lengths of borehole were isolated and the flow characteristics of the surrounding formation examined. In this report, a complete description of the test procedures, instrumentation, and measurement techniques is first given. The analytical/numerical methods used for data interpretation are then presented, followed by results of the interval and permeability tests. (The whole-hole tests are summarized in Appendix A.) Conclusions are presented in the final section

Assessment of spatial distrilbution of porosity and aquifer geohydraulic parameters in parts of the Tertiary - Quaternary hydrogeoresource of south-eastern Nigeria

Science.gov (United States)

George, N. J.; Akpan, A. E.; Akpan, F. S.

2017-12-01

An integrated attempt exploring information deduced from extensive surface resistivity study in three Local Government Areas of Akwa Ibom State, Nigeria and data from hydrogeological sources obtained from water boreholes have been explored to economically estimate porosity and coefficient of permeability/hydraulic conductivity in parts of the clastic Tertiary - Quaternary sediments of the Niger Delta region. Generally, these parameters are predominantly estimated from empirical analysis of core samples and pumping test data generated from boreholes in the laboratory. However, this analysis is not only costly and time consuming, but also limited in areal coverage. The chosen technique employs surface resistivity data, core samples and pumping test data in order to estimate porosity and aquifer hydraulic parameters (transverse resistance, hydraulic conductivity and transmissivity). In correlating the two sets of results, Porosity and hydraulic conductivity were observed to be more elevated near the riverbanks. Empirical models utilising Archie's, Waxman-Smits and Kozeny-Carman Bear relations were employed characterising the formation parameters with wonderfully deduced good fits. The effect of surface conduction occasioned by clay usually disregarded or ignored in Archie's model was estimated to be 2.58 × 10-5 Siemens. This conductance can be used as a corrective factor to the conduction values obtained from Archie's equation. Interpretation aided measures such as graphs, mathematical models and maps which geared towards realistic conclusions and interrelationship between the porosity and other aquifer parameters were generated. The values of the hydraulic conductivity estimated from Waxman-Smits model was approximately 9.6 × 10-5m/s everywhere. This revelation indicates that there is no pronounced change in the quality of the saturating fluid and the geological formations that serve as aquifers even though the porosities were varying. The deciphered parameter

The Researches on Reasonable Well Spacing of Gas Wells in Deep and low Permeability Gas Reservoirs

Science.gov (United States)

Bei, Yu Bei; Hui, Li; Lin, Li Dong

2018-06-01

This Gs64 gas reservoir is a condensate gas reservoir which is relatively integrated with low porosity and low permeability found in Dagang Oilfield in recent years. The condensate content is as high as 610g/m3. At present, there are few reports about the well spacing of similar gas reservoirs at home and abroad. Therefore, determining the reasonable well spacing of the gas reservoir is important for ensuring the optimal development effect and economic benefit of the gas field development. This paper discusses the reasonable well spacing of the deep and low permeability gas reservoir from the aspects of percolation mechanics, gas reservoir engineering and numerical simulation. considering there exist the start-up pressure gradient in percolation process of low permeability gas reservoir, this paper combined with productivity equation under starting pressure gradient, established the formula of gas well spacing with the formation pressure and start-up pressure gradient. The calculation formula of starting pressure gradient and well spacing of gas wells. Adopting various methods to calculate values of gas reservoir spacing are close to well testing' radius, so the calculation method is reliable, which is very important for the determination of reasonable well spacing in low permeability gas reservoirs.

SALTSTONE VARIABILITY STUDY - MEASUREMENT OF POROSITY

International Nuclear Information System (INIS)

Harbour, J; Vickie Williams, V; Tommy Edwards, T; Russell Eibling, R; Ray Schumacher, R

2007-01-01

One of the goals of the Saltstone Variability Study is to identify the operational and compositional variables that control or influence the important processing and performance properties of Saltstone mixes. One of the key performance properties is porosity which is a measure of the volume percent of a cured grout that is occupied by salt solution (for the saturated case). This report presents (1) the results of efforts to develop a method for the measurement of porosity of grout samples and (2) initial results of porosity values for samples that have been previously produced as part of the Saltstone Variability Study. A cost effective measurement method for porosity was developed that provides reproducible results, is relatively fast (30 to 60 minutes per sample) and uses a Mettler Toledo HR83 Moisture Analyzer that is already operational and routinely calibrated at Aiken County Technology Laboratory. The method involves the heating of the sample at 105 C until no further mass loss is observed. This mass loss value, which is due to water evaporation, is then used to calculate the volume percent porosity of the mix. The results of mass loss for mixes at 105 C were equivalent to the results obtained using thermal gravimetric analysis. The method was validated by comparing measurements of mass loss at 105 C for cured portland cement in water mixes to values presented in the literature for this system. A stereopycnometer from Quantachrome Instruments was selected to measure the cured grout bulk densities. Density is a property that is required to calculate the porosities. A stereopycnometer was already operational at Aiken County Technology Laboratory, has been calibrated using a solid stainless steel sphere of known volume, is cost effective and fast (∼15 minutes per sample). Cured grout densities are important in their own right because they can be used to project the volume of waste form produced from a given amount of salt feed of known composition. For mixes

Highly permeable, cement-bounded backfilling mortars for SMA repositories

International Nuclear Information System (INIS)

Jacobs, F.; Mayer, G.; Wittmann, F.H.

1994-03-01

In low- and intermediate-level waste repositories, gas is produced due e.g. to corrosion. This gas must be able to escape from the repository in order to prevent damage to the repository structure. A cement-based backfill should take over this function. For this purpose, the composition of cement-based materials was varied to study their influence on porosity and permeability. In parallel to this study the behaviour of fresh concrete, the liberation of the heat of hydration and the hardened concrete properties were investigated. To characterize the permeability of cement-based materials the following parameters are important: 1) composition of the material (pore fabric), 2) storage conditions (degree of saturation), 3) degree of hydration (age), 4) measuring fluid. A change in the composition of cement-based materials can vary the permeability by ten orders of magnitude. It is shown that, by using dense aggregates, the transport of the fluid takes place through the matrix and along the aggregate/matrix interface. By using porous aggregates the permeability can be increased by two orders of magnitude. In the case of a dense matrix, porous aggregates do not alter the permeability. Increasing the matrix content or interface content increases permeability. Hence light weight mortars are an obvious choice. Like-grained mixes showed higher permeabilities in combination with better mechanical properties but, in comparison to normal mixes, they showed worse flow properties. With the composition cement-: water-: aggregate content 1:0.4:5.33 the likegrained mix with aggregates ranging from 2 to 3 mm proved to be a suitable material. With a low compaction after 28 days this mix reaches a permeability of 4.10 -12 m 2 and an uniaxial cylinder compressive strength of 16 N/mm 2 . (author) 58 figs., 23 tabs., refs

Experimental study of very low permeability rocks using a high accuracy permeameter

International Nuclear Information System (INIS)

Larive, Elodie

2002-01-01

The measurement of fluid flow through 'tight' rocks is important to provide a better understanding of physical processes involved in several industrial and natural problems. These include deep nuclear waste repositories, management of aquifers, gas, petroleum or geothermal reservoirs, or earthquakes prevention. The major part of this work consisted of the design, construction and use of an elaborate experimental apparatus allowing laboratory permeability measurements (fluid flow) of very low permeability rocks, on samples at a centimetric scale, to constrain their hydraulic behaviour at realistic in-situ conditions. The accuracy permeameter allows the use of several measurement methods, the steady-state flow method, the transient pulse method, and the sinusoidal pore pressure oscillation method. Measurements were made with the pore pressure oscillation method, using different waveform periods, at several pore and confining pressure conditions, on different materials. The permeability of one natural standard, Westerly granite, and an artificial one, a micro-porous cement, were measured, and results obtained agreed with previous measurements made on these materials showing the reliability of the permeameter. A study of a Yorkshire sandstone shows a relationship between rock microstructure, permeability anisotropy and thermal cracking. Microstructure, porosity and permeability concepts, and laboratory permeability measurements specifications are presented, the permeameter is described, and then permeability results obtained on the investigated materials are reported [fr

Mechanistic Effects of Porosity on Structural Composite Materials

Science.gov (United States)

Siver, Andrew

As fiber reinforced composites continue to gain popularity as primary structures in aerospace, automotive, and powersports industries, quality control becomes an extremely important aspect of materials and mechanical engineering. The ability to recognize and control manufacturing induced defects can greatly reduce the likelihood of unexpected catastrophic failure. Porosity is the result of trapped volatiles or air bubbles during the layup process and can significantly compromise the strength of fiber reinforced composites. A comprehensive study was performed on an AS4C-UF3352 TCR carbon fiber-epoxy prepreg system to determine the effect of porosity on flexural, shear, low-velocity impact, and damage residual strength properties. Autoclave cure pressure was controlled to induce varying levels of porosity to construct six laminates with porosity concentrations between 0-40%. Porosity concentrations were measured using several destructive and nondestructive techniques including resin burnoff, sectioning and optical analysis, and X-ray computed tomography (CT) scanning. Ultrasonic transmission, thermography, and CT scanning provided nondestructive imaging to evaluate impact damage. A bilinear relationship accurately characterizes the change in mechanical properties with increasing porosity. Strength properties are relatively unaffected when porosity concentrations are below approximately 2.25% and decrease linearly by up to 40% in high porosity specimens.

Orthogonal Test Analysis on Conditions Affecting Electricity Generation Performance of an Enhanced Geothermal System at Yangbajing Geothermal Field

Directory of Open Access Journals (Sweden)

Yuchao Zeng

2017-12-01

Full Text Available The main conditions affecting electricity generation performance of an enhanced geothermal system (EGS include reservoir porosity, reservoir permeability, rock heat conductivity, water production rate and injection temperature. Presently there is lack of systematic research the relative importance of the five aforementioned conditions. The orthogonal test method is a statistical approach to analyze multi-factor and multi-level influence on system performance. In this work, based on the geological data at Yangbajing geothermal field, we analyzed the five conditions affecting the electricity generation performance of EGS, and ranked the relative importance of the five factors. The results show that the order of the relative importance of the conditions on electric power is water production rate > injection temperature > reservoir porosity > rock heat conductivity > reservoir permeability; the order of the relative importance of the conditions on reservoir impedance is reservoir permeability > injection temperature > water production rate > reservoir porosity > rock heat conductivity; the order of the relative importance of the conditions on pump power is water production rate > reservoir permeability > injection temperature > reservoir porosity > rock heat conductivity, and; the order of the relative importance of the conditions on energy efficiency is water production rate > reservoir permeability > reservoir porosity > injection temperature > rock heat conductivity. The construction of an EGS reservoir should be located at a formation with higher reservoir porosity or rock heat conductivity, while the determination of reservoir permeability, water production rate and injection temperature should be based on the comprehensive target.

Literature review and recommendation of methods for measuring relative permeability of anhydrite from the Salado Formation at the Waste Isolation Pilot Plant

Energy Technology Data Exchange (ETDEWEB)

Christiansen, R.L. [Colorado School of Mines, Golden, CO (United States). Dept. of Petroleum Engineering; Howarth, S.M. [Sandia National Labs., Albuquerque, NM (United States)

1995-08-01

This report documents a literature review of methods for measuring relative permeability as applied to low permeability anhydrite rock samples from the Salado Formation. About one hundred papers were reviewed, and four methods were identified as promising techniques for measuring the relative permeability of the Salado anhydrite: (1) the unsteady-state high-rate method, (2) the unsteady-state stationary-liquid method, (3) the unsteady-state centrifuge method, and (4) the unsteady-state low-rate method. Except for the centrifuge method, all have been used for low permeability rocks. The unsteady-state high-rate method is preferred for measuring relative permeability of Salado anhydrite, and the unsteady-state stationary-liquid method could be well suited for measuring gas relative permeability of Salado anhydrite. The unsteady-state low-rate method, which combines capillary pressure effects with relative permeability concepts may also prove effective. Likewise, the unsteady-state centrifuge method may be an efficient means for measuring brine relative permeability for Salado anhydrite, especially at high gas saturations.

Literature review and recommendation of methods for measuring relative permeability of anhydrite from the Salado Formation at the Waste Isolation Pilot Plant

International Nuclear Information System (INIS)

Christiansen, R.L.

1995-08-01

This report documents a literature review of methods for measuring relative permeability as applied to low permeability anhydrite rock samples from the Salado Formation. About one hundred papers were reviewed, and four methods were identified as promising techniques for measuring the relative permeability of the Salado anhydrite: (1) the unsteady-state high-rate method, (2) the unsteady-state stationary-liquid method, (3) the unsteady-state centrifuge method, and (4) the unsteady-state low-rate method. Except for the centrifuge method, all have been used for low permeability rocks. The unsteady-state high-rate method is preferred for measuring relative permeability of Salado anhydrite, and the unsteady-state stationary-liquid method could be well suited for measuring gas relative permeability of Salado anhydrite. The unsteady-state low-rate method, which combines capillary pressure effects with relative permeability concepts may also prove effective. Likewise, the unsteady-state centrifuge method may be an efficient means for measuring brine relative permeability for Salado anhydrite, especially at high gas saturations

Relative permeability of fractured wellbore cement: an experimental investigation using electrical resistivity monitoring for moisture content

Science.gov (United States)

Um, W.; Rod, K. A.; Strickland, C. E.

2016-12-01

Permeability is a critical parameter needed to understand flow in subsurface environments; it is particularly important in deep subsurface reservoirs where multiphase fluid flow is common, such as carbon sequestration and geothermal reservoirs. Cement is used in the annulus of wellbores due to its low permeable properties to seal aquifers, reducing leaks to adjacent strata. Extreme subsurface environments of CO2 storage and geothermal production conditions will eventually reduce the cement integrity, propagating fracture networks and increasing the permeability for air and/or water. To date, there have been no reproducible experimental investigations of relative permeability in fractured wellbore cement published. To address this gap, we conducted a series of experiments using fractured Portland cement monoliths with increasing fracture networks. The monolith cylinder sides were jacketed with heavy-duty moisture-seal heat-shrink tubing, then fractured using shear force applied via a hydraulic press. Fractures were generated with different severity for each of three monoliths. Stainless steel endcaps were fixed to the monoliths using the same shrink-wrapped jacket. Fracture characteristics were determined using X-ray microtomography and image analysis. Flow controllers were used to control flow of water and air to supply continuous water or water plus air, both of which were delivered through the influent end cap. Effluent air flow was monitored using a flow meter, and water flow was measured gravimetrically. To monitor the effective saturation of the fractures, a RCON2 concrete bulk electrical resistivity test device was attached across both endcaps and a 0.1M NaNO3 brine was used as the transport fluid to improve resistivity measurements. Water content correlated to resistivity measurements with a r2 > 0.96. Data from the experiments was evaluated using two relative permeability models, the Corey-curve, often used for modeling relative permeability in porous media

Permeability of shale at elevated temperature and pressure: Test methodology and preliminary results

International Nuclear Information System (INIS)

Myer, L.R.; Christian, T.L.

1987-05-01

A method of measuring the hydraulic conductivity of low permeability shale as a function of pressure and temperature has been developed and successfully demonstrated. Measurements have been performed on samples of Green River Formation up to a temperature of 140 0 C. For flow parallel to bedding hydraulic conductivities increased nonlinearly from 1.75 x 10 -16 m/s (1.6 x 10 -23 m 2 ) at 25 0 C, to 5.6 x 10 -15 m/s (1.4 x 10 -22 m 2 ) at 140 0 C. This increase in permeability with temperature may reflect an increase in microcrack porosity resulting from the heating

The neutron porosity tool

International Nuclear Information System (INIS)

Oelgaard, P.L.

1988-01-01

The report contains a review of available information on neutron porosity tools with the emphasis on dual thermal-neutron-detector porosity tools and epithermal-neutron-detector porosity tools. The general principle of such tools is discussed and theoretical models are very briefly reviewed. Available data on tool designs are summarized with special regard to the source-detector distance. Tool operational data, porosity determination and correction of measurements are briefly discussed. (author) 15 refs

Intestinal permeability of 51Cr-labelled ethylenediaminetetraacetic acid in patients with Crohn's disease and their healthy relatives

International Nuclear Information System (INIS)

Ainsworth, M.; Eriksen, J.; Rasmussen, J.W.; Muckadell, O.B.S. de

1989-01-01

An increased intestinal permeability has been proposed as an aetiologic factor in Crohn's disease. The 24-h urinary excretion of 100 μCi 51 Cr-labelled ethylenediaminetetraacetic acid (EDTA) was used to test the permeability in 15 patients with Crohn's disease and in 20 healthy first-degree relatives, who were known to have a genetic predisposition to inflammatory bowel disease. Twenty-eight healthy persons not related to patients with inflammatory bowel disease served as control material. The 51 Cr-EDTA excretion of the relatives was not significantly higher than that of the controls, whereas patients with Crohn's disease had a significantly higher excretion than both the relatives and the controls. Among patients the increased excretion was found only if the small intestine was involved. It is concluded that 1) as a group, patient with Crohn's disease in the small intestine have an increased intestinal permeability, in contrast to their healthy relatives, who have a normal permeability; 2) a considerable overlap of the results of the 51 Cr-EDTA test was found between the groups studied, and the test is not suitable for evaluating individual patients; 3) the results do not support the hypothesis of an increase in intestinal permeability as an aetiologic factor in Crohn's disease. 29 refs

Determining the mechanical properties of high porosity nickel

International Nuclear Information System (INIS)

Frappier, J.C.; Poirier, J.

1975-01-01

The following tests were carried out on high porosity (40 to 70%) sintered nickel: tensile tests, compression tests, diametral crushing tests, using strain gauges and extensometers. Results were obtained on the relationship elastic properties - porosity, Poisson coefficient in relation to deformation, variations of yield strength, and breaking stress. these various properties were also studied in relation to the sintering methods and the properties of the powders used [fr

Hydrogeology and geochemistry of low-permeability oil-shales - Case study from HaShfela sub-basin, Israel

Science.gov (United States)

Burg, Avihu; Gersman, Ronen

2016-09-01

Low permeability rocks are of great importance given their potential role in protecting underlying aquifers from surface and buried contaminants. Nevertheless, only limited data for these rocks is available. New appraisal wells drilled into the oil shale unit (OSU) of the Mt. Scopus Group in the HaShfela sub-basin, Central Israel, provided a one-time opportunity for detailed study of the hydrogeology and geochemistry of this very low permeability unit. Methods used include: slug tests, electrical logs, televiewer imaging, porosity and permeability measurements on core samples, chemical analyses of the rock column and groundwater analyses. Slug tests yielded primary indication to the low permeability of the OSU despite its high porosity (30-40%). Hydraulic conductivities as low as 10-10-10-12 m/s were calculated, using both the Hvorslev and Cooper-Bredehoeft-Papadopulos decoding methods. These low conductivities were confirmed by direct measurements of permeability in cores, and from calculations based on the Kozeny-Carman approach. Storativity was found to be 1 · 10-6 and specific storage - 3.8 · 10-9 m-1. Nevertheless, the very limited water flow in the OSU is argued to be driven gravitationally. The extremely slow recovery rates as well as the independent recovery of two adjacent wells, despite their initial large head difference of 214 m, indicate that the natural fractures are tight and are impermeable due to the confining stress at depth. Laboratory measured permeability is similar or even higher than the field-measured values, thereby confirming that fractures and bedding planes do not form continuous flow paths. The vertical permeability along the OSU is highly variable, implying hydraulic stratification and extremely low vertical hydraulic conductivity. The high salinity of the groundwater (6300-8000 mgCl/L) within the OSU and its chemical and isotopic compositions are explained by the limited water flow, suggesting long residence time of the water

Experimental Study on Gas Slippage of Tight Gas Sands in Kirthar Fold Belt Sindh, Pakistan

Directory of Open Access Journals (Sweden)

AFTAB AHMEDMAHESAR

2017-07-01

Full Text Available The laboratory experiments on samples from Kirthar fold belt of lower Indus basin Sindh Pakistan were carried out to investigate the effect of gas slippage under varying conditions of pore pressures and overburden stress. The samples were dried in an oven at temperature of 600C and were randomly selected for measurement of permeability and porosity. Permeability was measured using nitrogen gas, while the porosity measurements were made using helium gas expansion porosimeter. The bulk volume was determined by measuring sample diameter and length with caliper. The permeability results suggest that gas slippage increases as if low pore pressures are used, which leads to higher measured permeability than intrinsic permeability of samples. An attempt was also made to estimate the permeability using existing correlations and found that there is large scatter in predicted permeability and measured data. This large amount of scatter in the predicted permeability values concludes that unless absolutely necessary, such correlations should not be used where accurate absolute permeability values are needed. Moreover, the permeability and porosity were plotted together to develop a relation between two properties; the power law fitting of the data well explains the relation between permeability and effective porosity

A 2D double-porosity model for melting and melt migration beneath mid-oceanic ridges

Science.gov (United States)

Liu, B.; Liang, Y.; Parmentier, E.

2017-12-01

Several lines of evidence suggest that the melting and melt extraction region of the MORB mantle is heterogeneous consisting of an interconnected network of high permeability dunite channels in a low porosity harzburgite or lherzolite matrix. In principle, one can include channel formation into the tectonic-scale geodynamic models by solving conservation equations for a chemically reactive and viscously deformable porous medium. Such an approach eventually runs into computational limitations such as resolving fractal-like channels that have a spectrum of width. To better understand first order features of melting and melt-rock interaction beneath MOR, we have formulated a 2D double porosity model in which we treat the triangular melting region as two overlapping continua occupied by the low-porosity matrix and interconnected high-porosity channels. We use melt productivity derived from a thermodynamic model and melt suction rate to close our problem. We use a high-order accurate numerical method to solve the conservation equations in 2D for porosity, solid and melt velocities and concentrations of chemical tracers in the melting region. We carry out numerical simulations to systematically study effects of matrix-to-channel melt suction and spatially distributed channels on the distributions of porosity and trace element and isotopic ratios in the melting region. For near fractional melting with 10 vol% channel in the melting region, the flow field of the matrix melt follows closely to that of the solid because the small porosity (exchange between the melt and the solid. The smearing effect can be approximated by dispersion coefficient. For slowly diffusing trace elements (e.g., LREE and HFSE), the melt migration induced dispersion can be as effective as thermal diffusion. Therefore, sub-kilometer scale heterogeneities of Nd and Hf isotopes are significantly damped or homogenized in the melting region.

Mechanical, Permeability, and Degradation Properties of 3D Designed Poly(1,8 Octanediol-co-Citrate)(POC) Scaffolds for Soft Tissue Engineering

Science.gov (United States)

Jeong, Claire G.; Hollister, Scott J.

2015-01-01

Poly(1,8-octanediol-co-citric acid) (POC) is a synthetic biodegradable elastomer that can be processed into 3D scaffolds for tissue engineering. We investigated the effect of designed porosity on the mechanical properties, permeability and degradation profiles of the POC scaffolds. For mechanical properties, scaffold compressive data was fit to a 1D nonlinear elastic model and solid tensile data was fit to a Neohookean incompressible nonlinear elastic model. Chondrocytes were seeded on scaffolds to assess the biocompatibility of POC. Increased porosity was associated with increased degradation rate, increased permeability, and decreased mechanical stiffness which also became less nonlinear. Scaffold characterization in this paper will provide design guidance for POC scaffolds to meet the mechanical and biological parameters needed for engineering soft tissues such as cartilage. PMID:20091910

Experimental observation of permeability changes in dolomite at CO2 sequestration conditions.

Science.gov (United States)

Tutolo, Benjamin M; Luhmann, Andrew J; Kong, Xiang-Zhao; Saar, Martin O; Seyfried, William E

2014-02-18

Injection of cool CO2 into geothermally warm carbonate reservoirs for storage or geothermal energy production may lower near-well temperature and lead to mass transfer along flow paths leading away from the well. To investigate this process, a dolomite core was subjected to a 650 h, high pressure, CO2 saturated, flow-through experiment. Permeability increased from 10(-15.9) to 10(-15.2) m(2) over the initial 216 h at 21 °C, decreased to 10(-16.2) m(2) over 289 h at 50 °C, largely due to thermally driven CO2 exsolution, and reached a final value of 10(-16.4) m(2) after 145 h at 100 °C due to continued exsolution and the onset of dolomite precipitation. Theoretical calculations show that CO2 exsolution results in a maximum pore space CO2 saturation of 0.5, and steady state relative permeabilities of CO2 and water on the order of 0.0065 and 0.1, respectively. Post-experiment imagery reveals matrix dissolution at low temperatures, and subsequent filling-in of flow passages at elevated temperature. Geochemical calculations indicate that reservoir fluids subjected to a thermal gradient may exsolve and precipitate up to 200 cm(3) CO2 and 1.5 cm(3) dolomite per kg of water, respectively, resulting in substantial porosity and permeability redistribution.

A PERMEABLE ACTIVE AMENDMENT CONCRETE (PAAC) FOR CONTAMINANT REMEDIATION AND EROSION CONTROL

Energy Technology Data Exchange (ETDEWEB)

Knox, A.; Paller, M.; Dixon, K.

2012-06-29

The final project report for SEED SERDP ER - 2134 describes the development of permeable active amendment concrete (PAAC), which was evaluated through four tasks: 1) development of PAAC; 2) assessment of PAAC for contaminant removal; 3) evaluation of promising PAAC formulations for potential environmental impacts; and 4) assessment of the hydraulic, physical, and structural properties of PAAC. Conventional permeable concrete (often referred to as pervious concrete) is concrete with high porosity as a result of an extensive and interconnected void content. It is made from carefully controlled amounts of water and cementitious materials used to create a paste that forms a coating around aggregate particles. The mixture has a substantial void content (e.g., 15% - 25%) that results in a highly permeable structure that drains quickly. In PAAC, the aggregate material is partly replaced by chemically-active amendments that precipitate or adsorb contaminants in water that flows through the concrete interstices. PAAC combines the relatively high structural strength, ample void space, and water permeability of pervious concrete with the contaminant sequestration ability of chemically-active amendments to produce a new material with superior durability and ability to control contaminant mobility. The high surface area provided by the concrete interstices in PAAC provides significant opportunity for contaminants to react with the amendments incorporated into the concrete matrix. PAAC has the potential to immobilize a large variety of organic and inorganic contaminants by incorporating different active sequestering agents including phosphate materials (rock phosphate), organoclays, zeolite, and lime individually or in combinations.

Field determination of vertical permeability to air in the unsaturated zone

Science.gov (United States)

Weeks, Edwin P.

1978-01-01

The vertical permeability to air of layered materials in the unsaturated zone may be determined from air pressure data obtained at depth during a period when air pressure is changing at land surface. Such data may be obtained by monitoring barometric pressure with a microbarograph or surveying altimeter and simultaneously measuring down-hole pneumatic head differences in specially constructed piezometers. These data, coupled with air-filled porosity data from other sources, may be compared with the results of electric-analog or numerical solution of the one-dimensional diffusion equation to make a trial-and-error determination of the air permeability for each layer. The permeabilities to air may in turn be converted to equivalent hydraulic conductivity values if the materials are well drained, are permeable enough that the Klinkenberg effect is small, and are structurally unaffected by wetting. The method offers potential advantages over present methods to evaluate sites for artificial recharge by spreading; to evaluate ground-water pollution hazards from feedlots, sanitary landfills , and land irrigated with sewage effluent; and to evaluate sites for temporary storage of gas in the unsaturated zone. (Woodard-USGS)

Porosity and Health: Perspective of Traditional Persian Medicine

Science.gov (United States)

Tafazoli, Vahid; Nimrouzi, Majid; Daneshfard, Babak

2016-01-01

Background: The authors of this manuscript aimed to show the importance of porosity and condensation in health according to traditional Persian medicine (TPM) with consideration of new evidence in conventional medicine. Methods: Cardinal traditional medical and pharmacological texts were searched for the traditional terms of takhalkhol (porosity) and takassof (condensity) focused on preventive methods. The findings were classified and compared with new medical findings. Results: According to traditional Persian medicine, porosity and condensity are the two crucial items that contribute to human health. Somatotype is a taxonomy based on embryonic development, which may be considered in parallel with porosity and condensation. However, these terms are not completely the same. There are many causes for acquired porosity comprising hot weather, too much intercourse, rage, starvation, and heavy exercises. In general, porosity increases the risk of diseases as it makes the body organs vulnerable to external hot and cold weather. On the other hand, the porose organs are more susceptible to accumulation of morbid matters because the cellular wastes cannot be evacuated in the normal way. There are some common points between traditional and conventional medicine in the context of porosity and condensity. The relation between diet and somatotype is an example. Conclusion: Condensity and porosity are the two basic items cited in the TPM resources and contribute to health maintenance and disease prevention of body organs. Creating a balance between these two states in different body organs, strongly contributes to disease prevention, treatment and diminishing chronic diseases period. Choosing proper modality including diet, drug therapy, and manual therapy depends on the amount porosity and stiffness of the considered organ and the preferred porosity of the affected organ keeping in a normal healthy state. PMID:27840513

Plant fibre composites - porosity and stiffness

DEFF Research Database (Denmark)

Madsen, Bo; Thygesen, Anders; Lilholt, Hans

2009-01-01

Plant fibre composites contain typically a relatively large amount of porosity which influences their performance. A model, based on a modified rule of mixtures, is presented to include the influence of porosity on the composite stiffness. The model integrates the volumetric composition...... of the composites with their mechanical properties. The fibre weight fraction is used as an independent parameter to calculate the complete volumetric composition. A maximum obtainable stiffness of the composites is calculated at a certain transition fibre weight fraction, which is characterised by a best possible...... combination of high fibre volume fraction and low porosity. The model is validated with experimental data from the literature on several types of composites. A stiffness diagram is presented to demonstrate that the calculations can be used for tailoring and design of composites with a given profile...

Suitability of Torrent Permeability Tester to measure air-permeability of covercrete

Energy Technology Data Exchange (ETDEWEB)

Andrade, C.; Gonzales-Gasca, C. [Institute of Construction Sciences ' Eduardo Torroja' , Madrid (Spain); Torrent, R. [Portland Cement Institute, (Argentina)

2000-07-01

Suitability of the Torrent Permeability Tester (TPT) to measure the permeability of covercrete to air, both in the laboratory and the field, is investigated, and test results obtained in laboratory studies are discussed. The tests performed included the determination of air permeability (TPT method), oxygen permeability (Cembureau method) and capillary suction, rapid chloride permeability test (ASTM C 1202), as well as a one-year carbonation depth test. Concrete specimens of various compositions and curing regimes were used in the tests; the gas-permeability tests were repeated on the same specimens after 28 days, than again at 6 months and 12 months. Test results confirmed the suitability of the TPT as a useful tool in the characterization of the quality the of concrete cover. It was found to be sensitive to changes in concrete quality; repeatable for sensitive properties such as gas permeability ; also, it was found to correlate well with other durability-related properties. 10 refs., 8 tabs., 8 figs.

Data Qualification Report: Calculated Porosity and Porosity-Derived Values for Lithostratigraphic Units for use on the Yucca Mountain Project

Energy Technology Data Exchange (ETDEWEB)

P. Sanchez

2001-05-30

report uses technical assessment and corroboration to evaluate the original subject DTN. Rael (1999) provides many technical details of the technical assessment and corroboration methods and partially satisfies the intent of the qualification plan for this analysis. Rael presents a modified method based on Nelson (1996) to recompute porosity and porosity-derived values and uses some of the same inputs. Rael's (1999) intended purpose was to document porosity output relatively free of biases introduced by differing computational methods or parameter selections used for different boreholes. The qualification report necessarily evaluates the soundness of the pre-Process Validation and Re-engineering (PVAR) analyses and methodology, as reported in Rael (1999).

Data Qualification Report: Calculated Porosity and Porosity-Derived Values for Lithostratigraphic Units for use on the Yucca Mountain Project

International Nuclear Information System (INIS)

P. Sanchez

2001-01-01

technical assessment and corroboration to evaluate the original subject DTN. Rael (1999) provides many technical details of the technical assessment and corroboration methods and partially satisfies the intent of the qualification plan for this analysis. Rael presents a modified method based on Nelson (1996) to recompute porosity and porosity-derived values and uses some of the same inputs. Rael's (1999) intended purpose was to document porosity output relatively free of biases introduced by differing computational methods or parameter selections used for different boreholes. The qualification report necessarily evaluates the soundness of the pre-Process Validation and Re-engineering (PVAR) analyses and methodology, as reported in Rael (1999)

The Effect of Wettability Heterogeneity on Relative Permeability of Two-Phase Flow in Porous Media: A Lattice Boltzmann Study

Science.gov (United States)

Zhao, Jianlin; Kang, Qinjun; Yao, Jun; Viswanathan, Hari; Pawar, Rajesh; Zhang, Lei; Sun, Hai

2018-02-01

Relative permeability is a critical parameter characterizing multiphase flow in porous media and it is strongly dependent on the wettability. In many situations, the porous media are nonuniformly wet. To investigate the effect of wettability heterogeneity on relative permeability of two-phase flow in porous media, a multi-relaxation-time color-gradient lattice Boltzmann model is adopted to simulate oil/water two-phase flow in porous media with different oil-wet solid fractions. For the water phase, when the water saturation is high, the relative permeability of water increases with the increase of oil-wet solid fraction under a constant water saturation. However, as the water saturation decreases to an intermediate value (about 0.4-0.7), the relative permeability of water in fractionally wet porous media could be lower than that in purely water-wet porous media, meaning additional flow resistance exists in the fractionally wet porous media. For the oil phase, similar phenomenon is observed. This phenomenon is mainly caused by the wettability-related microscale fluid distribution. According to both our simulation results and theoretical analysis, it is found that the relative permeability of two-phase flow in porous media is strongly related to three parameters: the fluid saturation, the specific interfacial length of fluid, and the fluid tortuosity in the flow direction. The relationship between the relative permeability and these parameters under different capillary numbers is explored in this paper.

Relating porosity and mechanical properties in spray formed tubulars

International Nuclear Information System (INIS)

Payne, R.D.; Naval Surface Warfare Center, Annapolis, MD; Moran, A.L.; United States Naval Academy, Annapolis, MD; Cammarata, R.C.

1993-01-01

Because the spray forming process holds the potential to reduce the cost of alloy production, there is significant interest in developing methods to industrialized and automate this process through advanced sensing techniques. These advanced sensing techniques will observe the process real-time and give inputs to a process controller. By determining relationships between part quality, process parameters and sensor inputs, the process controller will be able to determine the quality of a part while it is being made and make adjustments if necessary. A Tinius-Olsen Tensile Tester was used to test five tensile specimens. The five tensile specimens were taken from five alloy 625 (60% Ni, 20% Cr, 8%Mo, 5% Fe) tubulars with varying properties. Among the advanced sensing techniques currently used to monitor the spray forming process is a surface roughness sensor. It consists of an argon laser, a charge coupled device (CCD) camera and roughness determination software. The laser emission is expanded into a long, thin line and projected onto the substrate as the molten metal consolidates on the surface. The roughness determination software will grab a frame with the laser stripe, digitize it and calculate the root mean square (RMS) value of the roughness in that particular frame. Each frame has a time stamp and can be related back to other time stamped process parameters. Recent sensor work has tried to find correlations between RMS values and porosities determined after processing. This venture has met with limited success. The object of this paper is to link porosity with mechanical properties and therefore define quality. Eventually the input from all sensors and process parameters will be entered into a process controller. If there is a link between sensor data and quality, this controller will be able to determine the quality of a forming material from sensor inputs and make changes in the process parameters if the quality is poor

Using artificial intelligence to predict permeability from petrographic data

Energy Technology Data Exchange (ETDEWEB)

Maqsood Ali; Adwait Chawathe [New Mexico Petroleum Recovery Research Centre (Mexico)

2000-10-01

Petrographic data collected during thin section analysis can be invaluable for understanding the factors that control permeability distribution. Reliable prediction of permeability is important for reservoir characterization. The petrographic elements (mineralogy, porosity types, cements and clays, and pore morphology) interact with each other uniquely to generate a specific permeability distribution. It is difficult to quantify accurately this interaction and its consequent effect on permeability, emphasizing the non-linear nature of the process. To capture these non-linear interactions, neural networks were used to predict permeability from petrographic data. The neural net was used as a multivariate correlative tool because of its ability to learn the non-linear relationships between multiple input and output variables. The study was conducted on the upper Queen formation called the Shattuck Member (Permian age). The Shattuck Member is composed of very fine-grained arkosic sandstone. The core samples were available from the Sulimar Queen and South Lucky Lake fields located in Chaves County, New Mexico. Nineteen petrographic elements were collected for each permeability value using a combined minipermeameter-petrographic technique. In order to reduce noise and overfitting the permeability model, these petrographic elements were screened, and their control (ranking) with respect to permeability was determined using fuzzy logic. Since the fuzzy logic algorithm provides unbiased ranking, it was used to reduce the dimensionality of the input variables. Based on the fuzzy logic ranking, only the most influential petrographic elements were selected as inputs for permeability prediction. The neural net was trained and tested using data from Well 1-16 in the Sulimar Queen field. Relying on the ranking obtained from the fuzzy logic analysis, the net was trained using the most influential three, five, and ten petrographic elements. A fast algorithm (the scaled conjugate

Complex permeability and core loss of soft magnetic Fe-based nanocrystalline powder cores

Energy Technology Data Exchange (ETDEWEB)

Füzerová, Jana, E-mail: jana.fuzerova@tuke.sk [Faculty of Mechanical Engineering, Technical University, Letná 1, 042 00 Košice (Slovakia); Füzer, Ján; Kollár, Peter [Institute of Physics, P.J. Šafárik University, Park Angelinum 9, 040 23 Košice (Slovakia); Bureš, Radovan; Fáberová, Mária [Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 043 53 Košice (Slovakia)

2013-11-15

Rapidly quenched ribbons of Fe{sub 73}Cu{sub 1}Nb{sub 3}Si{sub 16}B{sub 7} were ball milled and cryomilled to get powder and warm consolidated to get bulk compacts. The data presented here are relative to different experimental procedures, one corresponding to milling at room temperature (sample R1) and the other corresponding to cryomilling at temperature of liquid nitrogen (sample L1). It was found that the properties of the initial powder influenced the density, the electrical resistivity and electromagnetic properties of the resulting bulk alloys. Permeability and core loss are structure sensitive and depend on factors such as powder size and shape, porosity, purity, and internal stress. Permeability spectra of sample R1 decreases with increasing the frequency and its values are larger than that for sample L1 at low frequencies. On the other hand the permeability of sample L1 remains steady up to 1 kHz and at certain frequency is larger than that for sample R1. Also there are different frequency dependences of the imaginary parts of permeability and loss factor, respectively. The cryomilling of the amorphous ribbon positively influences on the AC magnetic properties at higher frequencies (above 100 Hz) of resulting bulk sample. - Highlights: • We prepared two different amorphous powder vitroperm samples. • We have examined changes in the properties of the bulk samples prepared by compaction. • It was found that properties of the initial powder influence the density, the electrical resistivity and electromagnetic properties of the resulting bulk alloys.

Three-dimensional characterization of microporosity and permeability in fault zones hosted in heterolithic succession

Science.gov (United States)

Riegel, H. B.; Zambrano, M.; Jablonska, D.; Emanuele, T.; Agosta, F.; Mattioni, L.; Rustichelli, A.

2017-12-01

The hydraulic properties of fault zones depend upon the individual contributions of the damage zone and the fault core. In the case of the damage zone, it is generally characterized by means of fracture analysis and modelling implementing multiple approaches, for instance the discrete fracture network model, the continuum model, and the channel network model. Conversely, the fault core is more difficult to characterize because it is normally composed of fine grain material generated by friction and wear. If the dimensions of the fault core allows it, the porosity and permeability are normally studied by means of laboratory analysis or in the other case by two dimensional microporosity analysis and in situ measurements of permeability (e.g. micro-permeameter). In this study, a combined approach consisting of fracture modeling, three-dimensional microporosity analysis, and computational fluid dynamics was applied to characterize the hydraulic properties of fault zones. The studied fault zones crosscut a well-cemented heterolithic succession (sandstone and mudstones) and may vary in terms of fault core thickness and composition, fracture properties, kinematics (normal or strike-slip), and displacement. These characteristics produce various splay and fault core behavior. The alternation of sandstone and mudstone layers is responsible for the concurrent occurrence of brittle (fractures) and ductile (clay smearing) deformation. When these alternating layers are faulted, they produce corresponding fault cores which act as conduits or barriers for fluid migration. When analyzing damage zones, accurate field and data acquisition and stochastic modeling was used to determine the hydraulic properties of the rock volume, in relation to the surrounding, undamaged host rock. In the fault cores, the three-dimensional pore network quantitative analysis based on X-ray microtomography images includes porosity, pore connectivity, and specific surface area. In addition, images were

Modeling of damage, permeability changes and pressure responses during excavation of the TSX tunnel in granitic rock at URL, Canada

Science.gov (United States)

Rutqvist, Jonny; Börgesson, Lennart; Chijimatsu, Masakazu; Hernelind, Jan; Jing, Lanru; Kobayashi, Akira; Nguyen, Son

2009-05-01

This paper presents numerical modeling of excavation-induced damage, permeability changes, and fluid-pressure responses during excavation of a test tunnel associated with the tunnel sealing experiment (TSX) at the Underground Research Laboratory (URL) in Canada. Four different numerical models were applied using a wide range of approaches to model damage and permeability changes in the excavation disturbed zone (EDZ) around the tunnel. Using in situ calibration of model parameters, the modeling could reproduce observed spatial distribution of damage and permeability changes around the tunnel as a combination of disturbance induced by stress redistribution around the tunnel and by the drill-and-blast operation. The modeling showed that stress-induced permeability increase above the tunnel is a result of micro and macrofracturing under high deviatoric (shear) stress, whereas permeability increase alongside the tunnel is a result of opening of existing microfractures under decreased mean stress. The remaining observed fracturing and permeability changes around the periphery of the tunnel were attributed to damage from the drill-and-blast operation. Moreover, a reasonably good agreement was achieved between simulated and observed excavation-induced pressure responses around the TSX tunnel for 1 year following its excavation. The simulations showed that these pressure responses are caused by poroelastic effects as a result of increasing or decreasing mean stress, with corresponding contraction or expansion of the pore volume. The simulation results for pressure evolution were consistent with previous studies, indicating that the observed pressure responses could be captured in a Biot model using a relatively low Biot-Willis’ coefficient, α ≈ 0.2, a porosity of n ≈ 0.007, and a relatively low permeability of k ≈ 2 × 10-22 m2, which is consistent with the very tight, unfractured granite at the site.

Porosity prediction from seismic inversion, Lavrans Field, Halten Terrace

Energy Technology Data Exchange (ETDEWEB)

Dolberg, David M.

1998-12-31

This presentation relates to porosity prediction from seismic inversion. The porosity prediction concerns the Lavrans Field of the Halten Terrace on the Norwegian continental shelf. The main themes discussed here cover seismic inversion, rock physics, statistical analysis - verification of well trends, upscaling/sculpting, and implementation. 2 refs., 6 figs.

Experimental study of very-low permeability rocks by the implementation of a precision permeameter

International Nuclear Information System (INIS)

Larive, E.

2002-12-01

The measurement of fluid flow through 'tight' rocks is important to provide a better understanding of physical processes involved in several industrial and natural problems. These include deep nuclear waste repositories, management of aquifers, gas, petroleum or geothermal reservoirs, or earthquakes prevention. The major part of this work consisted of the design, construction and use of an elaborate experimental apparatus allowing laboratory permeability measurements (fluid flow) of very low permeability rocks, on samples at a centimetric scale, to constrain their hydraulic behaviour at realistic in-situ conditions.The accuracy permeameter allows the use of several measurement methods, the steady-state flow method, the transient pulse method and the sinusoidal pore pressure oscillation method. Measurements were made with the pore pressure oscillation method, using different waveform periods, at several pore and confining pressure conditions on different materials. The permeability of one natural standard, Westerly granite, and an artificial one, a micro-porous cement, were measured and results obtained agreed with previous measurements made on these materials showing the reliability of the permeameter. A study of a Yorkshire sandstone shows a relationship between rock microstructure, permeability anisotropy and thermal cracking. Microstructure, porosity and permeability concepts, and laboratory permeability measurements specifications are presented, the permeameter is described, and then permeability results obtained on the investigated materials are reported. (author)

Effect of retrograde gas condensate in low permeability natural gas reservoir; Efeito da condensacao retrograda em reservatorios de gas natural com baixa permeabilidade

Energy Technology Data Exchange (ETDEWEB)

Chang, Paulo Lee K.C. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Faculdade de Engenharia Mecanica; Ligero, Eliana L.; Schiozer, Denis J. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Engenharia de Petroleo

2008-07-01

Most of Brazilian gas fields are low-permeability or tight sandstone reservoirs and some of them should be gas condensate reservoir. In this type of natural gas reservoir, part of the gaseous hydrocarbon mixture is condensate and the liquid hydrocarbon accumulates near the well bore that causes the loss of productivity. The liquid hydrocarbon formation inside the reservoir should be well understood such as the knowledge of the variables that causes the condensate formation and its importance in the natural gas production. This work had as goal to better understanding the effect of condensate accumulation near a producer well. The influence of the porosity and the absolute permeability in the gas production was studied in three distinct gas reservoirs: a dry gas reservoir and two gas condensate reservoirs. The refinement of the simulation grid near the producer well was also investigated. The choice of simulation model was shown to be very important in the simulation of gas condensate reservoirs. The porosity was the little relevance in the gas production and in the liquid hydrocarbon formation; otherwise the permeability was very relevant. (author)

Permeability and microstructural changes due to weathering of pyroclastic rocks in Cappadocia, central Turkey

Science.gov (United States)

Sato, M.; Takahashi, M.; Anma, R.; Shiomi, K.

2014-12-01

Studies of permeability changes of rocks during weathering are important to understand the processes of geomorphological development and how they are influenced by cyclic climatic conditions. Especially volcanic tuffs and pyroclastic flow deposits are easily affected by water absorption and freezing-thawing cycle (Erguler. 2009, Çelik and Ergül 2014). Peculiar erosional landscapes of Cappadocia, central Turkey, with numerous underground cities and carved churches, that made this area a world heritage site, are consists of volcanic tuffs and pyroclastic flow deposits. Understanding permeability changes of such rocks under different conditions are thus important not only to understand fundamental processes of weathering, but also to protect the landscapes of the world heritage sites and archaeological remains. In this study, we aim to evaluate internal void structures and bulk permeability of intact and weathered pyroclastic rocks from Cappadocia using X-ray CT, mercury intrusion porosimetry data and permeability measurement method of flow pump test. Samples of pyroclastic deposits that comprise the landscapes of Rose Valley and Ihlara Valley, were collected from the corresponding strata outside of the preservation areas. Porosity and pore-size distribution for the same samples measured by mercury intrusion porosimetry, indicate that the intact samples have lower porosity than weathered samples and pore sizes were dominantly 1-10μm in calculated radii, whereas weathered samples have more micropores (smaller than 1 μm). X-ray CT images were acquired to observe internal structure of samples. Micro-fractures, probably caused by repeated expansion and contraction due to temperature changes, were observed around clast grains. The higher micropore ratio in weathered samples could be attributed to the development of the micro-farctures. We will discuss fundamental processes of weathering and geomorphological development models using these data.

Effect of particle size distribution on permeability in the randomly packed porous media

Science.gov (United States)

Markicevic, Bojan

2017-11-01

An answer of how porous medium heterogeneity influences the medium permeability is still inconclusive, where both increase and decrease in the permeability value are reported. A numerical procedure is used to generate a randomly packed porous material consisting of spherical particles. Six different particle size distributions are used including mono-, bi- and three-disperse particles, as well as uniform, normal and log-normal particle size distribution with the maximum to minimum particle size ratio ranging from three to eight for different distributions. In all six cases, the average particle size is kept the same. For all media generated, the stochastic homogeneity is checked from distribution of three coordinates of particle centers, where uniform distribution of x-, y- and z- positions is found. The medium surface area remains essentially constant except for bi-modal distribution in which medium area decreases, while no changes in the porosity are observed (around 0.36). The fluid flow is solved in such domain, and after checking for the pressure axial linearity, the permeability is calculated from the Darcy law. The permeability comparison reveals that the permeability of the mono-disperse medium is smallest, and the permeability of all poly-disperse samples is less than ten percent higher. For bi-modal particles, the permeability is for a quarter higher compared to the other media which can be explained by volumetric contribution of larger particles and larger passages for fluid flow to take place.

Effect of sub-pore scale morphology of biological deposits on porous media flow properties

Science.gov (United States)

Ghezzehei, T. A.

2012-12-01

Biological deposits often influence fluid flow by altering the pore space morphology and related hydrologic properties such as porosity, water retention characteristics, and permeability. In most coupled-processes models changes in porosity are inferred from biological process models using mass-balance. The corresponding evolution of permeability is estimated using (semi-) empirical porosity-permeability functions such as the Kozeny-Carman equation or power-law functions. These equations typically do not account for the heterogeneous spatial distribution and morphological irregularities of the deposits. As a result, predictions of permeability evolution are generally unsatisfactory. In this presentation, we demonstrate the significance of pore-scale deposit distribution on porosity-permeability relations using high resolution simulations of fluid flow through a single pore interspersed with deposits of varying morphologies. Based on these simulations, we present a modification to the Kozeny-Carman model that accounts for the shape of the deposits. Limited comparison with published experimental data suggests the plausibility of the proposed conceptual model.

Experimental study of heavy oil-water flow structure effects on relative permeabilities in a fracture filled with heavy oil

Energy Technology Data Exchange (ETDEWEB)

Shad, S.; Gates, I.D.; Maini, B.B. [Calgary Univ., AB (Canada). Dept. of Chemical and Petroleum Engineering]|[Alberta Ingenuity Centre for In Situ Energy, Edmonton, AB (Canada)

2008-10-15

An experimental apparatus was used to investigate the flow of water in the presence of heavy oil within a smooth-walled fracture. Different flow patterns were investigated under a variety of flow conditions. Results of the experiments were used to determine the accuracy of VC, Corey, and Shad and Gates models designed to represent the behaviour of oil wet systems. The relative permeability concept was used to describe the behaviour of multiple phases flowing through porous media. A smooth-walled plexiglass Hele-Shaw cell was used to visualize oil and water flow. Changes in flow rates led to different flow regimes. The experiment demonstrated that water flowed co-currently in the form of droplets or slugs. Decreases in the oil flow rate enlarged the size of the water droplets as well as the velocity, until eventually the droplets coalesced and became water slugs. Droplet appearance or disappearance directly impacted the oil and water saturation levels. Changes in fluid saturation altered the pressure gradient. Darcy's law for the 2 liquid phases were used to calculate relative permeability curves. The study showed that at low water saturation, oil relative permeability reached as high as 2.5, while water relative permeability was lower than unity. In the presence of a continuous water channel, water drops formed in oil, and the velocity of the drops was lower than their velocity under a discontinuous water flow regime. It was concluded that the Shad and Gates model overestimated oil relative permeability and underestimated water relative permeability. 38 refs., 2 tabs., 9 figs.

Fabrication of slag-glass composite with controlled porosity

Directory of Open Access Journals (Sweden)

Ranko Adziski

2008-06-01

Full Text Available The preparation and performance of porous ceramics made from waste materials were investigated. Slag from thermal electrical plant Kakanj (Bosnia and Herzegovina with defined granulations: (0.500÷0.250 mm; (0.250÷0.125 mm; (0.125÷0.063 mm; (0.063÷0.045 mm and 20/10 wt.% of the waste TV screen glass with a granulation <0.063 mm were used for obtaining slag-glass composites with controlled porosity. The one produced from the slag powder fraction (0.125÷0.063 mm and 20 wt.% TV screen glass, sintered at 950°C/2h, was considered as the optimal. This system possesses open porosity of 26.8±1.0%, and interconnected pores with the size of 250–400 μm. The values of E-modulus and bending strength of this composite were 10.6±0.6 GPa and 45.7±0.7 MPa, respectively. The coefficient of thermal expansion was 8.47·10-6/°C. The mass loss in 0.1M HCl solution after 30 days was 1.2 wt.%. The permeability and the form coefficient of the porous composite were K0=0.12 Da and C0=4.53·105 m-1, respectively. The porous composite shows great potential to be used as filters, diffusers for water aeration, dust collectors, acoustic absorbers, etc.

Permeability of skin and oral mucosa to water and horseradish peroxidase as related to the thickness of the permeability barrier

International Nuclear Information System (INIS)

Squier, C.A.; Hall, B.K.

1985-01-01

The permeability of porcine skin and keratinized and nonkeratinized oral mucosa to tritium-labeled water and horseradish peroxidase (HRPO) was determined using perfusion chambers. Small blocks from each tissue were also incubated with HRPO and the extent of penetration visualized microscopically; this enabled measurements to be made of the thickness of the permeability barrier to this water-soluble tracer. Results obtained after inverting the oral mucosa in the chambers or adding metabolic inhibitors indicated that both compounds diffuse across the tissue. The permeability constants derived directly in the study showed that skin was less permeable than oral mucosa and that the floor of the mouth was significantly more permeable than all other regions. When these constants were normalized in terms of a standard permeability barrier thickness and the different tissues compared, the values obtained for skin were again less than those of the oral regions but, of these, the buccal mucosa was significantly higher. The difference in permeability between epidermis and keratinized oral epithelium may be due to differences in the volume density of membrane-coating granules known to exist between the tissues; differences between the oral mucosal regions may reflect differences in the nature of the intercellular barrier material

Large scale permeability test of the granite in the stipa mine and thermal conductivity test. Technical project report No. 2

International Nuclear Information System (INIS)

Lundstroem, L.; Stills, H.

1978-03-01

The investigated properties of the granite bedrock at Stripa may be summarized as follows: The permeability is very low, 0.4 x 10 -10 m/s, and independent of the pressure gradient. The permeability is reduced by 50 percent at a temperature increase from +10 0 C to +35 0 C. The thermal conductivity was determined in situ to be about 4 W/m 0 C which largely agrees with laboratory determinations. The effective porosity was determined to be 0.012 percent. 12 figs

Kozeny-Carman permeability relationship with disintegration process predicted from early dissolution profiles of immediate release tablets.

Science.gov (United States)

Kumari, Parveen; Rathi, Pooja; Kumar, Virender; Lal, Jatin; Kaur, Harmeet; Singh, Jasbir

2017-07-01

This study was oriented toward the disintegration profiling of the diclofenac sodium (DS) immediate-release (IR) tablets and development of its relationship with medium permeability k perm based on Kozeny-Carman equation. Batches (L1-L9) of DS IR tablets with different porosities and specific surface area were prepared at different compression forces and evaluated for porosity, in vitro dissolution and particle-size analysis of the disintegrated mass. The k perm was calculated from porosities and specific surface area, and disintegration profiles were predicted from the dissolution profiles of IR tablets by stripping/residual method. The disintegration profiles were subjected to exponential regression to find out the respective disintegration equations and rate constants k d . Batches L1 and L2 showed the fastest disintegration rates as evident from their bi-exponential equations while the rest of the batches L3-L9 exhibited the first order or mono-exponential disintegration kinetics. The 95% confidence interval (CI 95% ) revealed significant differences between k d values of different batches except L4 and L6. Similar results were also spotted for dissolution profiles of IR tablets by similarity (f 2 ) test. The final relationship between k d and k perm was found to be hyperbolic, signifying the initial effect of k perm on the disintegration rate. The results showed that disintegration profiling is possible because a relationship exists between k d and k perm . The later being relatable with porosity and specific surface area can be determined by nondestructive tests.

Modeling the Hydrologic Processes of a Permeable Pavement ...

Science.gov (United States)

A permeable pavement system can capture stormwater to reduce runoff volume and flow rate, improve onsite groundwater recharge, and enhance pollutant controls within the site. A new unit process model for evaluating the hydrologic performance of a permeable pavement system has been developed in this study. The developed model can continuously simulate infiltration through the permeable pavement surface, exfiltration from the storage to the surrounding in situ soils, and clogging impacts on infiltration/exfiltration capacity at the pavement surface and the bottom of the subsurface storage unit. The exfiltration modeling component simulates vertical and horizontal exfiltration independently based on Darcy’s formula with the Green-Ampt approximation. The developed model can be arranged with physically-based modeling parameters, such as hydraulic conductivity, Manning’s friction flow parameters, saturated and field capacity volumetric water contents, porosity, density, etc. The developed model was calibrated using high-frequency observed data. The modeled water depths are well matched with the observed values (R2 = 0.90). The modeling results show that horizontal exfiltration through the side walls of the subsurface storage unit is a prevailing factor in determining the hydrologic performance of the system, especially where the storage unit is developed in a long, narrow shape; or with a high risk of bottom compaction and clogging. This paper presents unit

Numerical analysis of pressure and porosity evolution in lava domes during periodic degassing conditions

Science.gov (United States)

Hyman, D.; Bursik, M. I.; Pitman, E. B.

2017-12-01

The collapse or explosive breakup of growing and degassing lava domes presents a significant hazard due to the generation of dense, mobile pyroclastic flows as well as the wide dispersal of dense ballistic blocks. Lava dome stability is in large part governed by the balance of transport and storage of gas within the pore space. Because pore pressurization reduces the effective stress within a dome, the transient distribution of elevated gas pressure is critically important to understanding dome break up. We combine mathematical and numerical analyses to gain a better understanding of the temporal variation in gas flow and storage within the dome system. In doing so, we develop and analyze new governing equations describing nonlinear gas pressure diffusion in a deforming dome with an evolving porosity field. By relating porosity, permeability, and pressure, we show that the flux of gas through a dome is highly sensitive to the porosity distribution and viscosity of the lava, as well as the timescale and magnitude of the gas supply. The numerical results suggest that the diffusion of pressure and porosity variations play an integral role in the cyclic growth and destruction of small domes.The nearly continuous cycles of lava dome growth, pressurization, and failure that have characterized the last two decades of eruptive history at Volcán Popocatépetl, Mexico provide excellent natural data with which to compare new models of transient dome pressurization. At Popocatépetl, periodic pressure increases brought on by changes in gas supply into the base of the dome may play a role in its cyclic growth and destruction behavior. We compare our model of cyclic pressurization with lava dome survival data from Popocatépetl. We show that transient changes in pore pressure explain how small lava domes evolve to a state of criticality before explosion or collapse. Additionally, numerical analyses presented here suggest that short-term oscillations cannot arise within the dome

3D numerical surface charge model including relative permeability : the general theory

NARCIS (Netherlands)

Casteren, van D.T.E.H.; Paulides, J.J.H.; Lomonova, E.A.

2014-01-01

One of the still "open" issues within low-frequency magnetics is the inclusion of µr in the calculations using the magnetic charge method. In this paper a new iterative method to take the relative permeability into account is investigated. Results show that the model accurately accounts for the

Porosity characterization for heterogeneous shales using integrated multiscale microscopy

Science.gov (United States)

Rassouli, F.; Andrew, M.; Zoback, M. D.

2016-12-01

Pore size distribution analysis plays a critical role in gas storage capacity and fluid transport characterization of shales. Study of the diverse distribution of pore size and structure in such low permeably rocks is withheld by the lack of tools to visualize the microstructural properties of shale rocks. In this paper we try to use multiple techniques to investigate the full pore size range in different sample scales. Modern imaging techniques are combined with routine analytical investigations (x-ray diffraction, thin section analysis and mercury porosimetry) to describe pore size distribution of shale samples from Haynesville formation in East Texas to generate a more holistic understanding of the porosity structure in shales, ranging from standard core plug down to nm scales. Standard 1" diameter core plug samples were first imaged using a Versa 3D x-ray microscope at lower resolutions. Then we pick several regions of interest (ROIs) with various micro-features (such as micro-cracks and high organic matters) in the rock samples to run higher resolution CT scans using a non-destructive interior tomography scans. After this step, we cut the samples and drill 5 mm diameter cores out of the selected ROIs. Then we rescan the samples to measure porosity distribution of the 5 mm cores. We repeat this step for samples with diameter of 1 mm being cut out of the 5 mm cores using a laser cutting machine. After comparing the pore structure and distribution of the samples measured form micro-CT analysis, we move to nano-scale imaging to capture the ultra-fine pores within the shale samples. At this stage, the diameter of the 1 mm samples will be milled down to 70 microns using the laser beam. We scan these samples in a nano-CT Ultra x-ray microscope and calculate the porosity of the samples by image segmentation methods. Finally, we use images collected from focused ion beam scanning electron microscopy (FIB-SEM) to be able to compare the results of porosity measurements

Chalk porosity and sonic velocity versus burial depth

DEFF Research Database (Denmark)

Fabricius, Ida Lykke; Gommesen, Lars; Krogsbøll, Anette Susanne

2008-01-01

Seventy chalk samples from four formations in the overpressured Danish central North Sea have been analyzed to investigate how correlations of porosity and sonic velocity with burial depth are affected by varying mineralogy, fluid pressure, and early introduction of petroleum. The results show th...... for fluid pressure because the cementing ions originate from stylolites, which are mechanically similar to fractures. We find that cementation occurs over a relatively short depth interval.......Seventy chalk samples from four formations in the overpressured Danish central North Sea have been analyzed to investigate how correlations of porosity and sonic velocity with burial depth are affected by varying mineralogy, fluid pressure, and early introduction of petroleum. The results show...... that porosity and sonic velocity follow the most consistent depth trends when fluid pressure and pore-volume compressibility are considered. Quartz content up to 10% has no marked effect, but more than 5% clay causes lower porosity and velocity. The mineralogical effect differs between P-wave and shear velocity...

Microsphere erosion in outer hydrogel membranes creating macroscopic porosity to counter biofouling-induced sensor degradation.

Science.gov (United States)

Vaddiraju, S; Wang, Y; Qiang, L; Burgess, D J; Papadimitrakopoulos, F

2012-10-16

Biofouling and tissue inflammation present major challenges toward the realization of long-term implantable glucose sensors. Following sensor implantation, proteins and cells adsorb on sensor surfaces to not only inhibit glucose flux but also signal a cascade of inflammatory events that eventually lead to permeability-reducing fibrotic encapsulation. The use of drug-eluting hydrogels as outer sensor coatings has shown considerable promise to mitigate these problems via the localized delivery of tissue response modifiers to suppress inflammation and fibrosis, along with reducing protein and cell absorption. Biodegradable poly (lactic-co-glycolic) acid (PLGA) microspheres, encapsulated within a poly (vinyl alcohol) (PVA) hydrogel matrix, present a model coating where the localized delivery of the potent anti-inflammatory drug dexamethasone has been shown to suppress inflammation over a period of 1-3 months. Here, it is shown that the degradation of the PLGA microspheres provides an auxiliary venue to offset the negative effects of protein adsorption. This was realized by: (1) the creation of fresh porosity within the PVA hydrogel following microsphere degradation (which is sustained until the complete microsphere degradation) and (2) rigidification of the PVA hydrogel to prevent its complete collapse onto the newly created void space. Incubation of the coated sensors in phosphate buffered saline (PBS) led to a monotonic increase in glucose permeability (50%), with a corresponding enhancement in sensor sensitivity over a 1 month period. Incubation in serum resulted in biofouling and consequent clogging of the hydrogel microporosity. This, however, was partially offset by the generated macroscopic porosity following microsphere degradation. As a result of this, a 2-fold recovery in sensor sensitivity for devices with microsphere/hydrogel composite coatings was observed as opposed to similar devices with blank hydrogel coatings. These findings suggest that the use of

Porosity measurement of amorphous materials by gamma ray transmission

International Nuclear Information System (INIS)

Poettker, Walmir Eno

2000-01-01

In this work it is presented the measurement of the total porosity of TRe soil, Sandstone Berea rocks and porous ceramics samples. For the determination of the total porosity, the Arquimedes method (conventional) and the gamma ray transmission methodology were employed. The porosity measurement using the gamma methodology has a significant advantage respect to the conventional method due to the fast and non-destructive determination, and also for supplying results with a greater characterization in small scales, in relation to the heterogeneity of the porosity. The conventional methodology presents good results only for homogeneous samples. The experimental set up for the gamma ray transmission technique consisted of a 241 Am source (59,53 keV), a NaI (Tl) scintillation detector, collimators, a XYZ, micrometric table and standard gamma spectrometry electronics connected to a multichannel analyser. (author)

Intestinal Permeability: The Basics

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Ingvar Bjarnason

1995-01-01

Full Text Available The authors review some of the more fundamental principles underlying the noninvasive assessment of intestinal permeability in humans, the choice of test markers and their analyses, and the practical aspects of test dose composition and how these can be changed to allow the specific assessment of regional permeability changes and other intestinal functions. The implications of increased intestinal permeability in the pathogenesis of human disease is discussed in relation to findings in patients with Crohn’s disease. A common feature of increased intestinal permeability is the development of a low grade enteropathy, and while quantitatively similar changes may be found in Crohn’s disease these seem to predict relapse of disease. Moreover, factors associated with relapse of Crohn’s disease have in common an action to increase intestinal permeability. While increased intestinal permeability does not seem to be important in the etiology of Crohn’s disease it may be a central mechanism in the clinical relapse of disease.

Sequence-Stratigraphic Analysis of the Regional Observation Monitoring Program (ROMP) 29A Test Corehole and Its Relation to Carbonate Porosity and Regional Transmissivity in the Floridan Aquifer System, Highlands County, Florida

Science.gov (United States)

Ward, W. C.; Cunningham, K.J.; Renken, R.A.; Wacker, M.A.; Carlson, J.I.

2003-01-01

layers are not thick, some intervals may exhibit lateral continuity because of their deposition on a broad low-relief ramp. A thick interval of thin vuggy zones and open faults forms thin conduit flow zones mixed with relatively thicker carbonate-rock diffuse flow zones between a depth of 1,070 and 1,244 feet below land surface (bottom of the test corehole). This interval is the most transmissive part of the Avon Park Formation penetrated in the ROMP 29A test corehole and is included in the highstand systems tract of the lower composite sequence. The Ocala Limestone is considered to be a semiconfining unit and contains three depositional sequences penetrated by the ROMP 29A test corehole. Deposited within deeper subtidal depositional cycles, no zones of enhanced porosity and permeability are expected in the Ocala Limestone. A thin erosional remnant of the shallow marine Suwannee Limestone overlies the Ocala Limestone, and permeability seems to be comparatively low because moldic porosity is poorly connected. Rocks that comprise the lower Hawthorn Group, Suwannee Limestone, and Ocala Limestone form a permeable upper zone of the Upper Floridan aquifer, and rocks of the lower Ocala Limestone and Avon Park Formation form a permeable lower zone of the Upper Floridan aquifer. On the basis of a preliminary analysis of transmissivity estimates for wells located north of Lake Okeechobee, spatial relations among groups of relatively high and low transmissivity values within the upper zone are evident. Upper zone transmissivity is generally less than 10,000 feet squared per day in areas located south of a line that extends through Charlotte, Sarasota, DeSoto, Highlands, Polk, Osceola, Okeechobee, and St. Lucie Counties. Transmissivity patterns within the lower zone of the Avon Park Formation cannot be regionally assessed because insufficient data over a wide areal extent have not been compiled.

Mechanical properties of permeable materials with an organized structure on the base of continuous metal fibers

International Nuclear Information System (INIS)

Karpinos, D.M.; Rutkovskij, A.E.; Zorin, V.A.; Ivanchuk, A.A.

1979-01-01

The mechanical properties were studied for permeable fibrous materials with an organized structure on the base of continuous metal fibers (from Kh18N9T steel) subjected to preliminary reprocessing volumetric net half-finished products. The effect of geometrical parameters of the net half-finished products and of their orientation in packing are shown to affect the mechanical properties within a wide range of porosities

Effect of Flow Direction on Relative Permeability Curves in Water/Gas Reservoir System: Implications in Geological CO2 Sequestration

Directory of Open Access Journals (Sweden)

Abdulrauf Rasheed Adebayo

2017-01-01

Full Text Available The effect of gravity on vertical flow and fluids saturation, especially when flow is against gravity, is not often a subject of interest to researchers. This is because of the notion that flow in subsurface formations is usually in horizontal direction and that vertical flow is impossible or marginal because of the impermeable shales or silts overlying them. The density difference between two fluids (usually oil and water flowing in the porous media is also normally negligible; hence gravity influence is neglected. Capillarity is also often avoided in relative permeability measurements in order to satisfy some flow equations. These notions have guided most laboratory core flooding experiments to be conducted in horizontal flow orientation, and the data obtained are as good as what the experiments tend to mimic. However, gravity effect plays a major role in gas liquid systems such as CO2 sequestration and some types of enhanced oil recovery techniques, particularly those involving gases, where large density difference exists between the fluid pair. In such cases, laboratory experiments conducted to derive relative permeability curves should take into consideration gravity effects and capillarity. Previous studies attribute directional dependence of relative permeability and residual saturations to rock anisotropy. It is shown in this study that rock permeability, residual saturation, and relative permeability depend on the interplay between gravity, capillarity, and viscous forces and also the direction of fluid flow even when the rock is isotropic. Rock samples representing different lithology and wide range of permeabilities were investigated through unsteady-state experiments covering drainage and imbibition in both vertical and horizontal flow directions. The experiments were performed at very low flow rates to capture capillarity. The results obtained showed that, for each homogeneous rock and for the same flow path along the core length

Electromagnetic methods for rapidly characterizing porosity distributions in the upper part of the Biscayne aquifer, southern Florida

Science.gov (United States)

Mount, G. J.; Comas, X.; Cunningham, K. J.

2010-12-01

Gregory J. Mount1, Xavier Comas1, and Kevin J. Cunningham2 1Department of Geosciences, Florida Atlantic University, Boca Raton, Florida 33431 2U.S. Geological Survey, 3110 SW 9th Avenue, Fort Lauderdale, Florida 33315 Although conventional hydrological techniques of aquifer characterization, which rely on data obtained from boreholes and wells can provide very valuable direct information about porosity, storativity and transmissivity, they are invasive and can often become time consuming and relatively expensive. Near-surface electromagnetic techniques, such as ground penetrating radar (GPR), provide indirect measurements of aquifer properties that complement traditional point measurements and provide a laterally continuous subsurface image in an efficient and cost effective manner with a minimal impact on the environment. We investigated the carbonate rocks of the uppermost part (3-5 meters) of the Biscayne aquifer in Everglades National Park to better understand the distribution of karst features that can create concentrated flow of groundwater, nutrients, and contaminants. As the Biscayne aquifer is the primary source of drinking water for millions of people in southern Palm Beach, Broward, and Miami-Dade counties, knowledge about these features could create a more complete understanding of a critical natural resource. These macroporous elements contribute to the overall storage, permeability, and transmissivity of the aquifer and for that reason, delineation of their distribution and areal extent should aid in the development of more accurate groundwater flow models. The macroporous elements create numerous hyperbolic diffractions in GPR common offset profiles, and these diffractions are used directly used to estimate two-dimensional (2D) models of electromagnetic (EM) wave velocity in the subsurface. Such models are further contrasted with one-dimensional (1D) velocity models using GPR common mid-point surveys at selected locations. In order to estimate

Effect of porosity on the tensile properties of low ductility aluminum alloys

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Gustavo Waldemar Mugica

2004-06-01

Full Text Available The literature contains reports of several studies correlating the porosity and mechanical properties of aluminum alloys. Most of these studies determine this correlation based on the parameter of global volumetric porosity. These reports, however, fail to separate the effects of microstructural features and porosity on alloys, though recognizing the influence of the latter on their mechanical properties. Thus, when the decrease in tensile strength due to the porosity effect is taken into account, the findings are highly contradictory. An analysis was made of the correlation between mechanical properties and global volumetric porosity and volumetric porosity in the fracture, as well as of the beta-Al5FeSi phase present in 380 aluminum alloy. Our findings indicate that mechanical properties in tension relating to global volumetric porosity lead to overestimations of the porosity effect in detriment to the mechanical properties. Moreover, the proposed models that take into account the effects of particles, both Si and beta-Al5FeSi, are unapplicable to low ductility alloys.

Tunable-Porosity Membranes From Discrete Nanoparticles

Science.gov (United States)

Marchetti, Patrizia; Mechelhoff, Martin; Livingston, Andrew G.

2015-01-01

Thin film composite membranes were prepared through a facile single-step wire-wound rod coating procedure in which internally crosslinked poly(styrene-co-butadiene) polymer nanoparticles self-assembled to form a thin film on a hydrophilic ultrafiltration support. This nanoparticle film provided a defect-free separation layer 130–150 nm thick, which was highly permeable and able to withstand aggressive pH conditions beyond the range of available commercial membranes. The nanoparticles were found to coalesce to form a rubbery film when heated above their glass transition temperature (Tg). The retention properties of the novel membrane were strongly affected by charge repulsion, due to the negative charge of the hydroxyl functionalized nanoparticles. Porosity was tuned by annealing the membranes at different temperatures, below and above the nanoparticle Tg. This enabled fabrication of membranes with varying performance. Nanofiltration properties were achieved with a molecular weight cut-off below 500 g mol−1 and a low fouling tendency. Interestingly, after annealing above Tg, memory of the interstitial spaces between the nanoparticles persisted. This memory led to significant water permeance, in marked contrast to the almost impermeable films cast from a solution of the same polymer. PMID:26626565

Relative permeabilities of supercritical CO2 and brine in carbon sequestration by a two-phase lattice Boltzmann method

Science.gov (United States)

Xie, Jian.-Fei.; He, S.; Zu, Y. Q.; Lamy-Chappuis, B.; Yardley, B. W. D.

2017-08-01

In this paper, the migration of supercritical carbon dioxide (CO2) in realistic sandstone rocks under conditions of saline aquifers, with applications to the carbon geological storage, has been investigated by a two-phase lattice Boltzmann method (LBM). Firstly the digital images of sandstone rocks were reproduced utilizing the X-ray computed microtomography (micro-CT), and high resolutions (up to 2.5 μm) were applied to the pore-scale LBM simulations. For the sake of numerical stability, the digital images were "cleaned" by closing the dead holes and removing the suspended particles in sandstone rocks. In addition, the effect of chemical reactions occurred in the carbonation process on the permeability was taken into account. For the wetting brine and non-wetting supercritical CO2 flows, they were treated as the immiscible fluids and were driven by pressure gradients in sandstone rocks. Relative permeabilities of brine and supercritical CO2 in sandstone rocks were estimated. Particularly the dynamic saturation was applied to improve the reliability of the calculations of the relative permeabilities. Moreover, the effects of the viscosity ratio of the two immiscible fluids and the resolution of digital images on the relative permeability were systematically investigated.

Thermal behavior of human eye in relation with change in blood perfusion, porosity, evaporation and ambient temperature.

Science.gov (United States)

Rafiq, Aasma; Khanday, M A

2016-12-01

Extreme environmental and physiological conditions present challenges for thermal processes in body tissues including multi-layered human eye. A mathematical model has been formulated in this direction to study the thermal behavior of the human eye in relation with the change in blood perfusion, porosity, evaporation and environmental temperatures. In this study, a comprehensive thermal analysis has been performed on the multi-layered eye using Pennes' bio-heat equation with appropriate boundary and interface conditions. The variational finite element method and MATLAB software were used for the solution purpose and simulation of the results. The thermoregulatory effect due to blood perfusion rate, porosity, ambient temperature and evaporation at various regions of human eye was illustrated mathematically and graphically. The main applications of this model are associated with the medical sciences while performing laser therapy and other thermoregulatory investigation on human eye. Copyright © 2016 Elsevier Ltd. All rights reserved.

Assessment of spatial distrilbution of porosity and aquifer geohydraulic parameters in parts of the Tertiary – Quaternary hydrogeoresource of south-eastern Nigeria

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N.J. George

2017-12-01

Full Text Available An integrated attempt exploring information deduced from extensive surface resistivity study in three Local Government Areas of Akwa Ibom State, Nigeria and data from hydrogeological sources obtained from water boreholes have been explored to economically estimate porosity and coefficient of permeability/hydraulic conductivity in parts of the clastic Tertiary – Quaternary sediments of the Niger Delta region. Generally, these parameters are predominantly estimated from empirical analysis of core samples and pumping test data generated from boreholes in the laboratory. However, this analysis is not only costly and time consuming, but also limited in areal coverage. The chosen technique employs surface resistivity data, core samples and pumping test data in order to estimate porosity and aquifer hydraulic parameters (transverse resistance, hydraulic conductivity and transmissivity. In correlating the two sets of results, Porosity and hydraulic conductivity were observed to be more elevated near the riverbanks. Empirical models utilising Archie’s, Waxman-Smits and Kozeny-Carman Bear relations were employed characterising the formation parameters with wonderfully deduced good fits. The effect of surface conduction occasioned by clay usually disregarded or ignored in Archie’s model was estimated to be 2.58 × 10−5 Siemens. This conductance can be used as a corrective factor to the conduction values obtained from Archie’s equation. Interpretation aided measures such as graphs, mathematical models and maps which geared towards realistic conclusions and interrelationship between the porosity and other aquifer parameters were generated. The values of the hydraulic conductivity estimated from Waxman-Smits model was approximately 9.6 × 10−5m/s everywhere. This revelation indicates that there is no pronounced change in the quality of the saturating fluid and the geological formations that serve as

Elastic-Brittle-Plastic Behaviour of Shale Reservoirs and Its Implications on Fracture Permeability Variation: An Analytical Approach

Science.gov (United States)

Masoudian, Mohsen S.; Hashemi, Mir Amid; Tasalloti, Ali; Marshall, Alec M.

2018-05-01

Shale gas has recently gained significant attention as one of the most important unconventional gas resources. Shales are fine-grained rocks formed from the compaction of silt- and clay-sized particles and are characterised by their fissured texture and very low permeability. Gas exists in an adsorbed state on the surface of the organic content of the rock and is freely available within the primary and secondary porosity. Geomechanical studies have indicated that, depending on the clay content of the rock, shales can exhibit a brittle failure mechanism. Brittle failure leads to the reduced strength of the plastic zone around a wellbore, which can potentially result in wellbore instability problems. Desorption of gas during production can cause shrinkage of the organic content of the rock. This becomes more important when considering the use of shales for CO2 sequestration purposes, where CO2 adsorption-induced swelling can play an important role. These phenomena lead to changes in the stress state within the rock mass, which then influence the permeability of the reservoir. Thus, rigorous simulation of material failure within coupled hydro-mechanical analyses is needed to achieve a more systematic and accurate representation of the wellbore. Despite numerous modelling efforts related to permeability, an adequate representation of the geomechanical behaviour of shale and its impact on permeability and gas production has not been achieved. In order to achieve this aim, novel coupled poro-elastoplastic analytical solutions are developed in this paper which take into account the sorption-induced swelling and the brittle failure mechanism. These models employ linear elasticity and a Mohr-Coulomb failure criterion in a plane-strain condition with boundary conditions corresponding to both open-hole and cased-hole completions. The post-failure brittle behaviour of the rock is defined using residual strength parameters and a non-associated flow rule. Swelling and shrinkage

Effects of phase transformation of steam-water relative permeabilities

Energy Technology Data Exchange (ETDEWEB)

Verma, A.K.

1986-03-01

A combined theoretical and experimental study of steam-water relative permeabilities (RPs) was carried out. First, an experimental study of two-phase concurrent flow of steam and water was conducted and a set of RP curves was obtained. These curves were compared with semi-empirical and experimental results obtained by other investigators for two-phase, two-component flow (oil/gas; gas/water; gas/oil). It was found that while the wetting phase RPs were in good agreement, RPs for the steam phase were considerably higher than the non-wetting phase RPs in two-component systems. This enhancement of steam RP is attributed to phase transformation effects at the pore level in flow channels. The effects of phase transformation were studied theoretically. This study indicates that there are two separate mechanisms by which phase transformation affects RP curves: (1) Phase transformation is converging-diverging flow channels can cause an enhancement of steam phase RP. In a channel dominated by steam a fraction of the flowing steam condenses upstream from the constriction, depositing its latent heat of condensation. This heat is conducted through the solid grains around the pore throat, and evaporation takes place downstream from it. Therefore, for a given bulk flow quality; a smaller fraction of steam actually flows through the throat segments. This pore-level effect manifests itself as relative permeability enhancement on a macroscopic level; and (2) phase transformation along the interface of a stagnant phase and the phase flowing around it controls the irreducible phase saturation. Therefore, the irreducible phase saturation in steam-water flow will depend, among other factors, on the boundary conditions of the flow.

Brazilian urban porosity : Treat or threat?

NARCIS (Netherlands)

Moreno Pessoa, I.; Tasan-Kok, M.T.; Korthals Altes, W.K.

2016-01-01

Urban areas have spatial discontinuities, such as disconnected neighbourhoods, brownfield areas and leftover places. They can be captured by the metaphor of urban porosity. This paper aims to highlight the potential social consequences of urban porosity by creating a ‘porosity index’. The authors

ABOUT CORRELATION BETWEEN THE PERCOLATION RATE OF MOISTURE THROUGH THE SEMI-PERMEABLE MEMBRANES AND THE STANDARD MEASUREMENTS OF THEIR PERMEABILITY OR EVAPORATIVE RESISTANCE

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В.Б. Роганков

2015-02-01

Full Text Available A variety of test methods to estimate the water vapour transmission (WVT-rate of thin membranes do not provide, unfortunately, the reliable basis to compare the permeability of different fabrics. Their results are crucially dependent on the details and construction of experimental methodologies as well as on the accepted by the different authors conditions of measurement. In this work, we propose the universal approach and demonstrate its adequate realization to compare the transport properties of any semi-permeable membranes measured by the conventional test-methods. The purpose is to avoid any confusion in such procedure of comparison. We have analysed below the WVT-rates measured by six alternative test-methods, which have been applied step-by-step to six different fabrics. In opposite to the widespread search for a pair correlation between the above results obtained by any two methods we treat them, in total, for each fabric in terms of the reduced variables. This approach is based on the novel concept of the moisture percolation (MP-rate which combines the diffusion and convective contributions in a transport process. It leads to the well-established general estimates of the normalized WVT-rates measured by the standard test-methods. Another advantage of the developed approach is its thermodynamic consistency, which offers the appropriate fluctuation model to take into account the porosity of any semi-permeable membranes.

Physical properties of Martian meteorites: Porosity and density measurements

Science.gov (United States)

Coulson, Ian M.; Beech, Martin; Nie, Wenshuang

Martian meteorites are fragments of the Martian crust. These samples represent igneous rocks, much like basalt. As such, many laboratory techniques designed for the study of Earth materials have been applied to these meteorites. Despite numerous studies of Martian meteorites, little data exists on their basic structural characteristics, such as porosity or density, information that is important in interpreting their origin, shock modification, and cosmic ray exposure history. Analysis of these meteorites provides both insight into the various lithologies present as well as the impact history of the planet's surface. We present new data relating to the physical characteristics of twelve Martian meteorites. Porosity was determined via a combination of scanning electron microscope (SEM) imagery/image analysis and helium pycnometry, coupled with a modified Archimedean method for bulk density measurements. Our results show a range in porosity and density values and that porosity tends to increase toward the edge of the sample. Preliminary interpretation of the data demonstrates good agreement between porosity measured at 100× and 300× magnification for the shergottite group, while others exhibit more variability. In comparison with the limited existing data for Martian meteorites we find fairly good agreement, although our porosity values typically lie at the low end of published values. Surprisingly, despite the increased data set, there is little by way of correlation between either porosity or density with parameters such as shock effect or terrestrial residency. Further data collection on additional meteorite samples is required before more definitive statements can be made concerning the validity of these observations.

Effect of Temperature and Age of Concrete on Strength – Porosity Relation

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T. Zadražil

2004-01-01

Full Text Available The compressive strengths of unsealed samples of concrete at the age of 180 days and have been measured at temperatures 20 °C, 300 °C, 600 °C and 900 °C. All of tests were performed for cold material. We compared our results with those obtained in [10] for the same type of concrete (age 28, resp. 90 days and measured at temperature ranging from 20 °C to 280 °C. Dependencies of compressive strength and porosity were correlated together and compared for the samples of age 28, 90 and 180 days. Behaviour of concrete of the age 90, resp. 180 days confirms generally accepted hypothesis that with increasing porosity strength of the concrete decreases. It has to be stressed out, howerer, that concrete samples of the age 28 days exhibit totally opposite dependency. 

Fault reactivation by fluid injection considering permeability evolution in fault-bordering damage zones

Science.gov (United States)

Yang, Z.; Yehya, A.; Rice, J. R.; Yin, J.

2017-12-01

Earthquakes can be induced by human activity involving fluid injection, e.g., as wastewater disposal from hydrocarbon production. The occurrence of such events is thought to be, mainly, due to the increase in pore pressure, which reduces the effective normal stress and hence the strength of a nearby fault. Change in subsurface stress around suitably oriented faults at near-critical stress states may also contribute. We focus on improving the modeling and prediction of the hydro-mechanical response due to fluid injection, considering the full poroelastic effects and not solely changes in pore pressure in a rigid host. Thus we address the changes in porosity and permeability of the medium due to the changes in the local volumetric strains. Our results also focus on including effects of the fault architecture (low permeability fault core and higher permeability bordering damage zones) on the pressure diffusion and the fault poroelastic response. Field studies of faults have provided a generally common description for the size of their bordering damage zones and how they evolve along their direction of propagation. Empirical laws, from a large number of such observations, describe their fracture density, width, permeability, etc. We use those laws and related data to construct our study cases. We show that the existence of high permeability damage zones facilitates pore-pressure diffusion and, in some cases, results in a sharp increase in pore-pressure at levels much deeper than the injection wells, because these regions act as conduits for fluid pressure changes. This eventually results in higher seismicity rates. By better understanding the mechanisms of nucleation of injection-induced seismicity, and better predicting the hydro-mechanical response of faults, we can assess methodologies and injection strategies to avoid risks of high magnitude seismic events. Microseismic events occurring after the start of injection are very important indications of when injection

A Permeable Active Amendment Concrete (PAAC) for Contaminant Remediation and Erosion Control

Science.gov (United States)

2012-06-01

system of highly permeable, interconnected voids that drain quickly. The low mortar content and high porosity combine to reduce the compressive...Initial Water Content, %: 5.5 Wet Unit Weight, pet : 88.7 Dry Unit Weight, pcf: 84.1 Compaction, %: N!A Hydraulic Conductivity, em/sec. @20 •c 4.0E...66.1 88.3 5 52.6 97.5 59.8 ~ r- 10 52.6 91.5 64.5 81.5 ~o. ofTriali Sample Max. Density Compaction Type ( pet ) % 7 1 UD N/A NIA a • SR:a of

Effect of the pore water composition on the diffusive anion transport in argillaceous, low permeability sedimentary rocks.

Science.gov (United States)

Wigger, Cornelia; Van Loon, Luc R

2018-06-01

The effect of the pore water composition on the diffusive anion transport was studied for two different argillaceous, low permeability sedimentary rocks, Opalinus Clay (OPA) and Helvetic Marl (HM). The samples were saturated with different solutions with varying molar concentration and different main cations in the solution: NaCl based pore solutions and CaCl 2 based pore solutions. The total porosity was measured by through-diffusion experiments with the neutral tracer HTO. Experiments performed in NaCl solutions resulted in a porosity of 0.12 for OPA and 0.03 for HM, and are consistent with results of the experiments in CaCl 2 solutions. The total porosity was independent of the molar concentration, in contrast to the measured anion porosity, which increased with increasing molar concentration. It could further be observed that the pore solution based on the bivalent cation calcium shielded the negative surface charge stronger than the monovalent cation sodium, resulting in a larger measureable anion-accessible porosity in the case of CaCl 2 solutions. The data was modelled based on an adapted Donnan approach of Birgersson and Karnland (2009). The model had to be adjusted with a permanent free, uncharged porosity, as well as with structural information on the permanent anion exclusion because of so-called bottleneck pores. Both parameters can only be evaluated from experiments. Nevertheless, taking these two adaptions into account, the effect of varying pore water compositions on the anion-accessible porosity of the investigated argillaceous rocks could be satisfactorily described. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of the pore water composition on the diffusive anion transport in argillaceous, low permeability sedimentary rocks

Science.gov (United States)

Wigger, Cornelia; Van Loon, Luc R.

2018-06-01

The effect of the pore water composition on the diffusive anion transport was studied for two different argillaceous, low permeability sedimentary rocks, Opalinus Clay (OPA) and Helvetic Marl (HM). The samples were saturated with different solutions with varying molar concentration and different main cations in the solution: NaCl based pore solutions and CaCl2 based pore solutions. The total porosity was measured by through-diffusion experiments with the neutral tracer HTO. Experiments performed in NaCl solutions resulted in a porosity of 0.12 for OPA and 0.03 for HM, and are consistent with results of the experiments in CaCl2 solutions. The total porosity was independent of the molar concentration, in contrast to the measured anion porosity, which increased with increasing molar concentration. It could further be observed that the pore solution based on the bivalent cation calcium shielded the negative surface charge stronger than the monovalent cation sodium, resulting in a larger measureable anion-accessible porosity in the case of CaCl2 solutions. The data was modelled based on an adapted Donnan approach of Birgersson and Karnland (2009). The model had to be adjusted with a permanent free, uncharged porosity, as well as with structural information on the permanent anion exclusion because of so-called bottleneck pores. Both parameters can only be evaluated from experiments. Nevertheless, taking these two adaptions into account, the effect of varying pore water compositions on the anion-accessible porosity of the investigated argillaceous rocks could be satisfactorily described.

Numerical Aspects Related to the Dynamic Update of Anisotropic Permeability Field During the Transport of Nanoparticles in the Subsurface

KAUST Repository

Chen, Meng-Huo

2016-06-01

Nanoparticles are particles that are between 1 and 100 nanometers in size. They present possible dangers to the environment due to the high surface to volume ratio, which can make the particles very reactive or catalytic. Furthermore, rapid increase in the implementation of nanotechnologies has released large amount of the nanowaste into the environment. In the last two decades, transport of nanoparticles in the subsurface and the potential hazard they impose to the environment have attracted the attention of researchers. In this work, we use numerical simulation to investigate the problem regarding the transport phenomena of nanoparticles in anisotropic porous media. We consider the case in which the permeability in the principal direction components will vary with respect to time. The interesting thing in this case is the fact that the anisotropy could disappear with time. We investigate the effect of the degenerating anisotropy on various fields such as pressure, porosity, concentration and velocities.

Numerical Aspects Related to the Dynamic Update of Anisotropic Permeability Field During the Transport of Nanoparticles in the Subsurface

KAUST Repository

Chen, Meng-Huo; Salama, Amgad; Ei-Amin, Mohamed

2016-01-01

Nanoparticles are particles that are between 1 and 100 nanometers in size. They present possible dangers to the environment due to the high surface to volume ratio, which can make the particles very reactive or catalytic. Furthermore, rapid increase in the implementation of nanotechnologies has released large amount of the nanowaste into the environment. In the last two decades, transport of nanoparticles in the subsurface and the potential hazard they impose to the environment have attracted the attention of researchers. In this work, we use numerical simulation to investigate the problem regarding the transport phenomena of nanoparticles in anisotropic porous media. We consider the case in which the permeability in the principal direction components will vary with respect to time. The interesting thing in this case is the fact that the anisotropy could disappear with time. We investigate the effect of the degenerating anisotropy on various fields such as pressure, porosity, concentration and velocities.

Modeling Permeability Alteration in Diatomite Reservoirs During Steam Drive, SUPRI TR-113

Energy Technology Data Exchange (ETDEWEB)

Bhat, Suniti Kumar; Kovscek, Anthony R.

1999-08-09

There is an estimated 10 billion barrels of original oil in place (OOIP) in diatomaceous reservoirs in Kern County, California. These reservoirs have low permeability ranging from 0.1 to 10 mD. Injection pressure controlled steam drive has been found to be an effective way to recover oil from these reservoir. However, steam drive in these reservoirs has its own complications. The rock matrix is primarily silica (SiO2). It is a known fact that silica is soluble in hot water and its solubility varies with temperature and pH. Due to this fact, the rock matrix in diatomite may dissolve into the aqueous phase as the temperature at a location increases or it may precipitate from the aqueous phase onto the rock grains as the temperature decreases. Thus, during steam drive silica redistribution will occur in the reservoir along with oil recovery. This silica redistribution causes the permeability and porosity of the reservoir to change. Understanding and quantifying these silica redistribution effects on the reservoir permeability might prove to be a key aspect of designing a steam drive project in these formations.

Stem sapwood permeability in relation to crown dominance and site quality in self-thinning fire-origin lodgepole pine stands.

Science.gov (United States)

Reid, Douglas E B; Silins, Uldis; Lieffers, Victor J

2003-08-01

Stem sapwood hydraulic permeability, tree leaf area, sapwood basal area, earlywood to latewood ratio of annual rings, radial variation in hydraulic permeability and stem hydraulic capacity were examined in dominant (D), codominant (CD) and suppressed (SP) lodgepole pine (Pinus contorta Dougl. ex Loud.) trees growing on medium and poor sites. Hydraulic permeability on a sapwood area basis (ks) was lower in suppressed trees (0.71 x 10(-12) m2) compared to dominants (1.97 x 10(-12) m2) and codominants (1.79 x 10(-12) m2), and higher on medium than on poor sites. The leaf/sapwood area ratio (S) varied with crown dominance position (D > CD > SP) but not by site type. Leaf specific conductivity (kL) did not vary between crown classes or site types. The relationship between leaf area and stem hydraulic supply capacity (Q*) was strong, but differed among crown classes. Dominant trees and trees from the medium sites had a greater proportion of earlywood in outer rings of sapwood than suppressed trees. Sapwood permeability declined from the cambium to the sapwood-heartwood boundary in all samples, but the decline was more gradual in dominant trees compared to codominant and suppressed trees; differences in the radial variation in sapwood permeability may be related to differences in S. Sapwood permeability is positively related to crown dominance, whereas subdominant (CD and SP) trees have greater Q* in relation to leaf area, leading us to propose that this may give subdominant trees a survival advantage, slowing self-thinning.

Regional-dependent intestinal permeability and BCS classification: elucidation of pH-related complexity in rats using pseudoephedrine.

Science.gov (United States)

Fairstein, Moran; Swissa, Rotem; Dahan, Arik

2013-04-01

Based on its lower Log P value relative to metoprolol, a marker for the low/high-permeability (P(eff)) class boundary, pseudoephedrine was provisionally classified as BCS low-permeability compound. On the other hand, following oral administration, pseudoephedrine fraction dose absorbed (F(abs)) and systemic bioavailability approaches 100%. This represents a challenge to the generally recognized P(eff)-F(abs) correlation. The purpose of this study was to elucidate the underlying mechanisms behind the confusion in pseudoephedrine's BCS classification. Pseudoephedrine's BCS solubility class was determined, and its physicochemical properties and intestinal permeability were thoroughly investigated, both in vitro and in vivo in rats, considering the complexity of the whole of the small intestine. Pseudoephedrine was found to be unequivocally a high-solubility compound. All of the permeability studies revealed similar phenomenon; at any given intestinal segment/pH, the permeability of metoprolol was higher than that of pseudoephedrine, however, as the intestinal region becomes progressively distal, and the pH gradually increases, pseudoephedrine's permeability rises above that of metoprolol in the former segment. This unique permeability pattern likely explains pseudoephedrine's complete absorption. In conclusion, pseudoephedrine is a BCS Class I compound; no discrepancy between P(eff) and F(abs) is involved in its absorption. Rather, it reflects the complexity behind P(eff) when considering the whole of the intestine. We propose to allow high-permeability classification to drugs with P(eff) that matches/exceeds the low/high class benchmark anywhere throughout the intestinal tract and not restricted necessarily to the jejunum.

Mueller matrix polarimetry on plasma sprayed thermal barrier coatings for porosity measurement.

Science.gov (United States)

Luo, David A; Barraza, Enrique T; Kudenov, Michael W

2017-12-10

Yttria-stabilized zirconia (YSZ) is the most widely used material for thermal plasma sprayed thermal barrier coatings (TBCs) used to protect gas turbine engine parts in demanding operation environments. The superior material properties of YSZ coatings are related to their internal porosity level. By quantifying the porosity level, tighter control on the spraying process can be achieved to produce reliable coatings. Currently, destructive measurement methods are widely used to measure the porosity level. In this paper, we describe a novel nondestructive approach that is applicable to classify the porosity level of plasma sprayed YSZ TBCs via Mueller matrix polarimetry. A rotating retarder Mueller matrix polarimeter was used to measure the polarization properties of the plasma sprayed YSZ coatings with different porosity levels. From these measurements, it was determined that a sample's measured depolarization ratio is dependent on the sample's surface roughness and porosity level. To this end, we correlate the depolarization ratio with the samples' surface roughness, as measured by a contact profilometer, as well as the total porosity level, in percentage measured using a micrograph and stereological analysis. With the use of this technique, a full-field and rapid measurement of porosity level can be achieved.

Wheel traffic effect on air-filled porosity and air permeability in a soil catena across the wheel rut

DEFF Research Database (Denmark)

Berisso, Feto Esimo; Schjønning, Per; Lamandé, Mathieu

might induce different effects on soil physical properties. The objective of this study was to investigate the impact of vehicle traffic on soil physical properties and air permeability by systematic collection of samples in a transect running from the center to the outside of the wheel rut. A field...... catena running from center of the wheel rut to un wheeled part of the field ( 0, 20, 40, 50,60 and 400 cm horizontal distance). We measured water retention and air permeability (ka) at -30, -100 and -300 hPa matric potentials. At -100 hPa, we obtained consistently lower air filled under the wheel rut......The impact of wheel traffic on soil physical properties is usually quantified by randomly collecting soil cores at specific depths below the wheeled surface. However, modeling studies as well as few measurements indicated a non-uniform stress distribution in a catena across the wheel rut, which...

Properties of chipboard

International Nuclear Information System (INIS)

Baryeh, E.A.

1993-03-01

Density, permeability, porosity, water absorption and swelling characteristics have been assessed for chipboard made out of saw dust and an adhesive. Results indicated that permeability increases as porosity increases and both decrease with increase in board density. Permeability, 1/α and porosity, p were found to relate to the density, ρ as follows: 1/α = Ae aρ and p = Be bρ while porosity and permeability were found to follow the relation: p = C(1/α) d . It was also found that the lower the board density, the higher its water absorption and swelling. Thermal conductivity, specific heat and calorific value were also assessed. Results revealed that thermal conductivity increases nonlinearly with increasing density, while it decreases linearly with increasing porosity. Specific heat also increases linearly with increasing density and temperature. However, calorific value was found to be independent of density. Mechanical properties increase as the density increases except for the penetration depth. It was found that the tensile strength, modulus of rupture, shear strength, hardness, resistance to cutting and impact strength vary linearly with the density, while the degree of elasticity has a nonlinear relation with the density. The board is generally stronger in bending than in compression and tension in descending order of strength. (author). 18 refs, figs

Gas and water permeability of concrete for reactor buildings small specimens

International Nuclear Information System (INIS)

Mills, R.H.

1986-03-01

The effect on permeability of artifical aging by drying shrinkage and by freeze-thaw was determined by observing mass transfer of gas and water under a pressure gradient. It was found that damage due to freeze-thaw was negligible but that cracking around aggregate caused by drying shrinkage resulted in significantly increased permeability to both gas and water. The absence of freeze-thaw damage was attributed to self-dessication. Since the concrete was not exposed to an external source of water, the chemical reaction was sustained by consumption of mixing water. The resulting air voids were, apparently, sufficient to absorb expansive pressures due to ice formation. The response to lateral prestress was different for cracked and uncracked concrete. Although, in all cases, increased prestress resulted in reduced leakage, the effect was stronger in cracked concrete. Mean pore diameter as determined by gas diffusion was not, however, substantially affected because the leakage in cracked concrete remained very low. Reinforcing steel did not have a great influence on permeability of small specimens. Gas transmission through concrete was strongly influenced by moisture content. Free moisture constituted a barrier to gas flow, acting as a virtual solid. This is important since aging of concrete results in reduced free moisture. Ultrasonic pulse velocity appeared to vary with moisture content and porosity of concrete in the same way as gas permeability and gave promise of being effective for in-situ monitoring of concrete in reactor buildings

Determination of reservoir effective porosity using nuclear magnetic logging data

International Nuclear Information System (INIS)

Aksel'rod, S.M.; Danevich, V.I.; Sadykov, D.M.

1979-01-01

In connection with the development of nuclear magnetic logging (NML) the possibility has occurred to determine the effective porosity coefficient for rocks directly under the conditions of their occurrence. The initial amplitude of a signal of free precession of NML is proportional to the quantity of free fluid in the rock volume, which is determined by the index of free fluid (IFF). On the basis of the laboratory studies it is shown that the relation between IFF and free water content is always linear and doesn't depend on lithological characteristics of rocks, porous dimensions and distribution. Using this relation it's possible to estimate bound water content. While filling the reservoir with weakly mineralized water the IFF value coincides numerically with the effective porosity coefficient. Otherwise the content of hydrogen nuclei in a volume unit is much less; while calculating the effective porosity coefficient this fact is recorded by the index of the amplitude decrease which depends on temperature and increases with its growth (for oils). In strata containing intercalations of reservoirs and non-reservoirs the averaged according to stratum IFF value determines the mean-weighted values of effective porosity

In situ measurements of rock salt permeability changes due to nearby excavation

International Nuclear Information System (INIS)

Stormont, J.C.; Howard, C.L.; Daemen, J.J.K.

1991-07-01

The Small-Scale Mine-By was an in situ experiment to measure changes in brine and gas permeability of rock salt as a result of nearby excavation. A series of small-volume pressurized brine- and gas-filled test intervals were established 8 m beneath the floor of Room L1 in the WIPP underground. The test intervals were isolated in the bottom of the 4.8-cm diameter monitoring boreholes with inflatable rubber packers, and are initially pressurized to about 2 MPa. Both brine- and gas-filled test intervals were located 1.25, 1.5, 2, 3, and 4 r from the center of a planned large-diameter hole, where r is the radius of the large-diameter hole. Prior to the drilling of the large-diameter borehole, the responses of both the brine- and gas-filled test intervals were consistent with the formation modeled as a very low permeability, low porosity porous medium with a significant pore (brine) pressure and no measurable gas permeability. The drilling of the mine-by borehole created a zone of dilated, partially saturated rock out to about 1.5 r. The formation pressure increases from near zero at 1.5 r to the pre-excavation value at 4 r. Injection tests reveal a gradient of brine permeabilities from 5 x 10 -18 m 2 at 1.25 r to about the pre-excavation value (10 -21 m 2 ) by 3 r. Gas-injection tests reveal measurable gas permeability is limited to within 1.5 r. 17 refs., 24 figs., 6 tabs

Regional-Dependent Intestinal Permeability and BCS Classification: Elucidation of pH-Related Complexity in Rats Using Pseudoephedrine

OpenAIRE

Fairstein, Moran; Swissa, Rotem; Dahan, Arik

2013-01-01

Based on its lower Log P value relative to metoprolol, a marker for the low/high-permeability (Peff) class boundary, pseudoephedrine was provisionally classified as BCS low-permeability compound. On the other hand, following oral administration, pseudoephedrine fraction dose absorbed (Fabs) and systemic bioavailability approaches 100%. This represents a challenge to the generally recognized Peff–Fabs correlation. The purpose of this study was to elucidate the underlying mechanisms behind the ...

3D-printing porosity: A new approach to creating elevated porosity materials and structures.

Science.gov (United States)

Jakus, A E; Geisendorfer, N R; Lewis, P L; Shah, R N

2018-05-01

We introduce a new process that enables the ability to 3D-print high porosity materials and structures by combining the newly introduced 3D-Painting process with traditional salt-leaching. The synthesis and resulting properties of three 3D-printable inks comprised of varying volume ratios (25:75, 50:50, 70:30) of CuSO 4 salt and polylactide-co-glycolide (PLGA), as well as their as-printed and salt-leached counterparts, are discussed. The resulting materials are comprised entirely of PLGA (F-PLGA), but exhibit porosities proportional to the original CuSO 4 content. The three distinct F-PLGA materials exhibit average porosities of 66.6-94.4%, elastic moduli of 112.6-2.7 MPa, and absorbency of 195.7-742.2%. Studies with adult human mesenchymal stem cells (hMSCs) demonstrated that elevated porosity substantially promotes cell adhesion, viability, and proliferation. F-PLGA can also act as carriers for weak, naturally or synthetically-derived hydrogels. Finally, we show that this process can be extended to other materials including graphene, metals, and ceramics. Porosity plays an essential role in the performance and function of biomaterials, tissue engineering, and clinical medicine. For the same material chemistry, the level of porosity can dictate if it is cell, tissue, or organ friendly; with low porosity materials being far less favorable than high porosity materials. Despite its importance, it has been difficult to create three-dimensionally printed structures that are comprised of materials that have extremely high levels of internal porosity yet are surgically friendly (able to handle and utilize during surgical operations). In this work, we extend a new materials-centric approach to 3D-printing, 3D-Painting, to 3D-printing structures made almost entirely out of water-soluble salt. The structures are then washed in a specific way that not only extracts the salt but causes the structures to increase in size. With the salt removed, the resulting medical polymer

FEM Analyses for T-H-M-M Coupling Processes in Dual-Porosity Rock Mass under Stress Corrosion and Pressure Solution

Directory of Open Access Journals (Sweden)

Yu-Jun Zhang

2012-01-01

Full Text Available The models of stress corrosion and pressure solution established by Yasuhara et al. were introduced into the 2D FEM code of thermo-hydro-mechanical-migratory coupling analysis for dual-porosity medium developed by the authors. Aiming at a hypothetical model for geological disposal of nuclear waste in an unsaturated rock mass from which there is a nuclide leak, two computation conditions were designed. Then the corresponding two-dimensional numerical simulation for the coupled thermo-hydro-mechanical-migratory processes were carried out, and the states of temperatures, rates and magnitudes of aperture closure, pore and fracture pressures, flow velocities, nuclide concentrations and stresses in the rock mass were investigated. The results show: the aperture closure rates caused by stress corrosion are almost six orders higher than those caused by pressure solution, and the two kinds of closure rates climb up and then decline, furthermore tend towards stability; when the effects of stress corrosion and pressure solution are considered, the negative fracture pressures in near field rise very highly; the fracture aperture and porosity are decreases in the case 1, so the relative permeability coefficients reduce, therefore the nuclide concentrations in pore and fracture in this case are higher than those in case 2.

Effect of persistent high intraocular pressure on microstructure and hydraulic permeability of trabecular meshwork

International Nuclear Information System (INIS)

Mei Xi; Ren Lin; Xu Qiang; Liu Zhi-Cheng; Zheng Wei

2015-01-01

As the aqueous humor leaves the eye, it first passes through the trabecular meshwork (TM). Increased flow resistance in this region causes elevation of intraocular pressure (IOP), which leads to the occurrence of glaucoma. To quantitatively evaluate the effect of high IOP on the configuration and hydraulic permeability of the TM, second harmonic generation (SHG) microscopy was used to image the microstructures of the TM and adjacent tissues in control (normal) and high IOP conditions. Enucleated rabbit eyes were perfused at a pressure of 60 mmHg to achieve the high IOP. Through the anterior chamber of the eye, in situ images were obtained from different depths beneath the surface of the TM. Porosity and specific surface area of the TM in control and high IOP conditions were then calculated to estimate the effect of the high pressure on the permeability of tissue in different depths. We further photographed the histological sections of the TM and compared the in situ images. The following results were obtained in the control condition, where the region of depth was less than 55 μm with crossed branching beams and large pores in the superficial TM. The deeper meshwork is a silk-like tissue with abundant fluorescence separating the small size of pores. The total thickness of pathway tissues composed of TM and juxtacanalicular (JCT) is more than 100 μm. After putting a high pressure on the inner wall of the eye, the TM region progressively collapses and decreases to be less than 40 μm. Fibers of the TM became dense, and the porosity at 34 μm in the high IOP condition is comparable to that at 105 μm in the control condition. As a consequent result, the permeability of the superficial TM decreases rapidly from 120 μm 2 to 49.6 μm 2 and that of deeper TM decreases from 1.66 μm 2 to 0.57 μm 2 . Heterogeneity reflected by descent in permeability reduces from 12.4 μm of the control condition to 3.74 μm of the high IOP condition. The persistently high IOP makes the

Gas and Water Permeability of Concrete

Energy Technology Data Exchange (ETDEWEB)

Villar, M. V.; Martin, P. L.; Romero, F. J.; Gutierrez-Rodirgo, V.; Barcala, J. M.

2012-11-01

The gas pressure of concrete samples was measured in an unsteady-state equipment working under low injection pressures and in a newly fine tuned steady-state setup working under different pressures. These measurements allowed the estimation of the intrinsic and relative gas permeability of the concrete and of the effect of boundary conditions on them. Permeability decreased with water content, but it was also greatly affected by the hydraulic history of concrete, i.e. if it had been previously dried or wetted. In particular, and for a given degree of saturation, the gas permeability of concrete previously saturated was lower than if the concrete had been just air dried or saturated after air drying. In any case, the gas permeability was about two orders of magnitude higher than the liquid water permeability (10-16 vs. 10-18 m2), probably due to the chemical reactions taking place during saturation (carbonation). The relative gas permeability of concrete increased sharply for water degrees of saturation smaller than 50%. The boundary conditions also affected the gas permeability, which seemed to be mostly conditioned by the back pressure and the confining pressure, increasing as the former increased and decreasing as the latter increased, i.e. decreasing as the effective pressure increased. Overall the increase of pressure head or injection pressure implied a decrease in gas permeability. External,microcracking during air-drying could not be ruled out as responsible for the decrease of permeability with confining pressure. The apparent permeability obtained applying the Klinkenberg method for a given effective pressure was only slightly smaller than the average of all the values measured for the same confining pressure range. For this reason it is considered that the Klinkenberg effect was not relevant in the range of pressures applied. (Author) 37 refs.

Gas diffusion, non-Darcy air permeability, and computed tomography images of a clay subsoil affected by compaction

DEFF Research Database (Denmark)

Schjønning, Per; Lamandé, Mathieu; Berisso, Feto Esimo

2013-01-01

Soil productivity and other soil functions are dependent on processes in the untilled subsoil. Undisturbed soil cores were collected at the 0.3- to 0.4-m depth from a heavy clay soil in Finland subjected to a single heavy traffic event by agricultural machinery three decades before sampling....... Untrafficked control plots were used as a reference. Computed tomography (CT) scanning was performed on soil cores at a field-sampled field capacity water content. Gas diffusion and air permeability were measured when the soil cores were drained to −1000 hPa matric potential (air permeability also at −100...... and −300 hPa). The air-filled pore space was measured with an air pycnometer and also calculated from mass balance and CT data. Gas diffusion and air permeability were also measured on a straight model tube and on autoclaved aerated concrete. The compaction treatment had not influenced soil total porosity...

A casting and imaging technique for determining void geometry and relative permeability behavior of a single fracture specimen

Energy Technology Data Exchange (ETDEWEB)

Cox, B.L.; Pruess, K.; Persoff, P.

1990-01-01

A casting technique has been developed for making translucent replicas of the void space of natural rock fractures. Attenuation of light shined through the cast combined with digital image analysis provides a pointwise definition of fracture apertures. The technique has been applied to a fracture specimen from Dixie Valley, Nevada, and the measured void space geometry has been used to develop theoretical predictions of two-phase relative permeability. A strong anisotropy in relative permeabilities has been found, which is caused by highly anisotropic spatial correlations among fracture apertures. 16 refs., 6 figs.

New Technique for TOC Estimation Based on Thermal Core Logging in Low-Permeable Formations (Bazhen fm.)

Science.gov (United States)

Popov, Evgeny; Popov, Yury; Spasennykh, Mikhail; Kozlova, Elena; Chekhonin, Evgeny; Zagranovskaya, Dzhuliya; Belenkaya, Irina; Alekseev, Aleksey

2016-04-01

A practical method of organic-rich intervals identifying within the low-permeable dispersive rocks based on thermal conductivity measurements along the core is presented. Non-destructive non-contact thermal core logging was performed with optical scanning technique on 4 685 full size core samples from 7 wells drilled in four low-permeable zones of the Bazhen formation (B.fm.) in the Western Siberia (Russia). The method employs continuous simultaneous measurements of rock anisotropy, volumetric heat capacity, thermal anisotropy coefficient and thermal heterogeneity factor along the cores allowing the high vertical resolution (of up to 1-2 mm). B.fm. rock matrix thermal conductivity was observed to be essentially stable within the range of 2.5-2.7 W/(m*K). However, stable matrix thermal conductivity along with the high thermal anisotropy coefficient is characteristic for B.fm. sediments due to the low rock porosity values. It is shown experimentally that thermal parameters measured relate linearly to organic richness rather than to porosity coefficient deviations. Thus, a new technique employing the transformation of the thermal conductivity profiles into continuous profiles of total organic carbon (TOC) values along the core was developed. Comparison of TOC values, estimated from the thermal conductivity values, with experimental pyrolytic TOC estimations of 665 samples from the cores using the Rock-Eval and HAWK instruments demonstrated high efficiency of the new technique for the organic rich intervals separation. The data obtained with the new technique are essential for the SR hydrocarbon generation potential, for basin and petroleum system modeling application, and estimation of hydrocarbon reserves. The method allows for the TOC richness to be accurately assessed using the thermal well logs. The research work was done with financial support of the Russian Ministry of Education and Science (unique identification number RFMEFI58114X0008).

Transverse Chemotactic Migration of Bacteria from High to Low Permeability Regions in a Dual Permeability Porous Microfluidic Device

Science.gov (United States)

Singh, R.; Olson, M. S.

2011-12-01

Low permeability regions sandwiched between high permeability regions such as clay lenses are difficult to treat using conventional treatment methods. Trace concentrations of contaminants such as non-aqueous phase liquids (NAPLs) remain trapped in these regions and over the time diffuse out into surrounding water thereby acting as a long term source of groundwater contamination. Bacterial chemotaxis (directed migration toward a contaminant source), may be helpful in enhancing bioremediation of such contaminated sites. This study is focused on simulating a two-dimensional dual-permeability groundwater contamination scenario using microfluidic devices and evaluating transverse chemotactic migration of bacteria from high to low permeability regions. A novel bi-layer polydimethylsiloxane (PDMS) microfluidic device was fabricated using photolithography and soft lithography techniques to simulate contamination of a dual- permeability region due to leakage from an underground storage tank into a low permeability region. This device consists of a porous channel through which a bacterial suspension (Escherchia Coli HCB33) is flown and another channel for injecting contaminant/chemo-attractant (DL-aspertic acid) into the porous channel. The pore arrangement in the porous channel contains a 2-D low permeability region surrounded by high permeability regions on both sides. Experiments were performed under chemotactic and non-chemotactic (replacing attractant with buffer solution in the non porous channel) conditions. Images were captured in transverse pore throats at cross-sections 4.9, 9.8, and 19.6 mm downstream from the attractant injection point and bacteria were enumerated in the middle of each pore throat. Bacterial chemotaxis was quantified in terms of the change in relative bacterial counts in each pore throat at cross-sections 9.8 and 19.6 mm with respect to counts at the cross-section at 4.9 mm. Under non-chemotactic conditions, relative bacterial count was observed

Root porosity and radial oxygen loss related to arsenic tolerance and uptake in wetland plants

International Nuclear Information System (INIS)

Li, H.; Ye, Z.H.; Wei, Z.J.; Wong, M.H.

2011-01-01

The rates of radial oxygen loss (ROL), root porosity, concentrations of arsenic (As), iron (Fe) and manganese (Mn) in shoot and root tissues and on root surfaces, As tolerances, and their relationships in different wetland plants were investigated based on a hydroponic experiment (control, 0.8, 1.6 mg As L -1 ) and a soil pot trail (control, 60 mg As kg -1 ). The results revealed that wetland plants showed great differences in root porosity (9-64%), rates of ROL (55-1750 mmo1 O 2 kg -1 root d.w. d -1 ), As uptake (e.g., 8.8-151 mg kg -1 in shoots in 0.8 mg As L -1 treatment), translocation factor (2.1-47% in 0.8 mg As L -1 ) and tolerance (29-106% in 0.8 mg As L -1 ). Wetland plants with higher rates of ROL and root porosity tended to form more Fe/Mn plaque, possess higher As tolerance, higher concentrations of As on root surfaces and a lower As translocation factor so decreasing As toxicity. - Research highlights: → There is significant correlation between the porosity of roots and rates of ROL. → The rates of ROL are significantly correlated with tolerance indices and concentrations of As, Fe, Mn on root surface. → The rates of ROL is negatively correlated with As translocation factor. - Wetland plants with high rates of ROL tended to form more Fe plaque on root surfaces and possess higher As tolerance.

Investigating the development of less-mobile porosity in realistic hyporheic zone sediments with COMSOL Multiphysics

Science.gov (United States)

MahmoodPoorDehkordy, F.; Briggs, M. A.; Day-Lewis, F. D.; Bagtzoglou, A. C.

2017-12-01

Although hyporheic zones are often modeled at the reach scale as homogeneous "boxes" of exchange, heterogeneity caused by variations of pore sizes and connectivity is not uncommon. This heterogeneity leads to the creation of more- and less-mobile zones of hydraulic exchange that influence reactive solute transport processes. Whereas fluid sampling is generally sensitive to more-mobile zones, geoelectrical measurement is sensitive to ionic tracer dynamics in both less- and more-mobile zones. Heterogeneity in pore connectivity leads to a lag between fluid and bulk electrical conductivity (EC) resulting in a hysteresis loop, observed during tracer breakthrough tests, that contains information about the less-mobile porosity attributes of the medium. Here, we present a macro-scale model of solute transport and electrical conduction developed using COMSOL Multiphysics. The model is used to simulate geoelectrical monitoring of ionic transport for bed sediments based on (1) a stochastic sand-and-cobble mixture and (2) a dune feature with strong permeability layering. In both of these disparate sediment types, hysteresis between fluid and bulk EC is observed, and depends in part on fluid flux rate through the model domain. Using the hysteresis loop, the ratio of less-mobile to mobile porosity and mass-transfer coefficient are estimated graphically. The results indicate the presence and significance of less-mobile porosity in the hyporheic zones and demonstrate the capability of the proposed model to detect heterogeneity in flow processes and estimate less-mobile zone parameters.

Controlling porosity of porous carbon cathode for lithium oxygen batteries: Influence of micro and meso porosity

Science.gov (United States)

Kim, Minjae; Yoo, Eunjoo; Ahn, Wha-Seung; Shim, Sang Eun

2018-06-01

In rechargeable lithium-oxygen (Li-O2) batteries, the porosity of porous carbon materials plays a crucial role in the electrochemical performance serving as oxygen diffusion path and Li ion transfer passage. However, the influence of optimization of porous carbon as an air electrode on cell electrochemical performance remains unclear. To understand the role of carbon porosity in Li-O2 batteries, carbon materials featuring controlled pore sizes and porosity, including C-800 (nearly 96% microporous) and AC-950 (55:45 micro/meso porosity), are designed and synthesized by carbonization using a triazine-based covalent organic polymer (TCOP). We find that the microporous C-800 cathode allows 120 cycles with a limited capacity of 1000 mAh g-1, about 2 and 10 times higher than that of mixed-porosity AC-950 and mesoporous CMK-3, respectively. Meanwhile, the specific discharge capacity of the C-800 electrode at 200 mA g-1 is 6003 mAh g-1, which is lower than that of the 8433 and 9960 mAh g-1 when using AC-950 and CMK-3, respectively. This difference in the electrochemical performance of the porous carbon cathode with different porosity causes to the generation and decomposition of Li2O2 during the charge and discharge cycle, which affects oxygen diffusion and Li ion transfer.

4D synchrotron X-ray imaging to understand porosity development in shales during exposure to hydraulic fracturing fluid

Science.gov (United States)

Kiss, A. M.; Bargar, J.; Kohli, A. H.; Harrison, A. L.; Jew, A. D.; Lim, J. H.; Liu, Y.; Maher, K.; Zoback, M. D.; Brown, G. E.

2016-12-01

Unconventional (shale) reservoirs have emerged as the most important source of petroleum resources in the United States and represent a two-fold decrease in greenhouse gas emissions compared to coal. Despite recent progress, hydraulic fracturing operations present substantial technical, economic, and environmental challenges, including inefficient recovery, wastewater production and disposal, contaminant and greenhouse gas pollution, and induced seismicity. A relatively unexplored facet of hydraulic fracturing operations is the fluid-rock interface, where hydraulic fracturing fluid (HFF) contacts shale along faults and fractures. Widely used, water-based fracturing fluids contain oxidants and acid, which react strongly with shale minerals. Consequently, fluid injection and soaking induces a host of fluid-rock interactions, most notably the dissolution of carbonates and sulfides, producing enhanced or "secondary" porosity networks, as well as mineral precipitation. The competition between these mechanisms determines how HFF affects reactive surface area and permeability of the shale matrix. The resultant microstructural and chemical changes may also create capillary barriers that can trap hydrocarbons and water. A mechanistic understanding of the microstructure and chemistry of the shale-HFF interface is needed to design new methodologies and fracturing fluids. Shales were imaged using synchrotron micro-X-ray computed tomography before, during, and after exposure to HFF to characterize changes to the initial 3D structure. CT reconstructions reveal how the secondary porosity networks advance into the shale matrix. Shale samples span a range of lithologies from siliceous to calcareous to organic-rich. By testing shales of different lithologies, we have obtained insights into the mineralogic controls on secondary pore network development and the morphologies at the shale-HFF interface and the ultimate composition of produced water from different facies. These results

Reconstruction of 3D Micro Pore Structure of Coal and Simulation of Its Mechanical Properties

Directory of Open Access Journals (Sweden)

Guang-zhe Deng

2017-01-01

Full Text Available This article takes the low permeability coal seam in the coalfield of South Judger Basin in Xinjiang, as a research object. The pore structure characteristics of coal rock mass in low permeability coal seam were analyzed quantitatively using scanning electron microscopy (SEM through the methods of statistics and digital image analysis. Based on the pore structure parameters and the distribution function of the coal rock mass, a three-dimensional porous cylinder model with different porosity was reconstructed by FLAC3D. The numerical simulation study of reconstructed pore model shows that (1 the porosity and the compressive strength have obvious nonlinear relation and satisfy the negative exponential relation; (2 the porosity significantly affects the stress distribution; with the increase of micro porosity, the stress distribution becomes nonuniform; (3 the compressive failures of different models are mainly shear failures, and the shape of fracture section is related to porosity; (4 the variation of seepage coefficient of the pore reconstruction model is consistent with the development of micro cracks. The micro mechanism of the deformation and failure of coal and the interaction of multiphase flow with porosity are revealed, which provides a theoretical reference for the clean development of the low permeability coal seam.

Diffusion-Coefficients of Sulfate and Methane in Marine-Sediments - Influence of Porosity

DEFF Research Database (Denmark)

IVERSEN, N.; JØRGENSEN, BB

1993-01-01

diffusion coefficients can be related to the diffusion coefficient in free solution by D(s) = D(o)/theta2, where theta is the tortuosity of the sediment. The sediment tortuosity calculated from this equation showed a linear relationship with sediment porosity (phi) over the porosity range of 0.4-0.9. From...

Estimation of In Situ Stress and Permeability from an Extended Leak-off Test

Science.gov (United States)

Nghiep Quach, Quoc; Jo, Yeonguk; Chang, Chandong; Song, Insun

2016-04-01

stress regime with the information of the maximum principal stress that will be estimated based on borehole breakout geometry analysis. To estimate the in situ permeability from the XLOT data, we derived a theoretical equation that relates the slope of pressure versus injected water volume (P-V) curve to permeability based on the Darcy's law. The equation is expressed in terms of permeability as a function of some key parameters such as open-hole dimensions, flowrate, porosity, pressure change and injected water volume. We applied this equation to the early stage of the P-V curves prior to the leak-off point to prevent the effect of induced fractures on permeability. The estimated in situ permeability was (3.1±0.4)×10-17m2, which turns out to be quite similar to the laboratory measurements in recovered cores.

Root porosity and radial oxygen loss related to arsenic tolerance and uptake in wetland plants

Energy Technology Data Exchange (ETDEWEB)

Li, H. [State Key Laboratory for Bio-control, and School of Life Sciences, Sun Yat-sen University, Guangzhou 510006 (China); Croucher Institute for Environmental Sciences, and Department of Biology, Hong Kong Baptist University, Kowloon Tong (Hong Kong); Ye, Z.H., E-mail: lssyzhh@mail.sysu.edu.c [State Key Laboratory for Bio-control, and School of Life Sciences, Sun Yat-sen University, Guangzhou 510006 (China); Wei, Z.J. [School of Information and Technology, Guangdong University of Foreign Studies, Guangzhou 510275 (China); Wong, M.H., E-mail: mhwong@hkbu.edu.h [Croucher Institute for Environmental Sciences, and Department of Biology, Hong Kong Baptist University, Kowloon Tong (Hong Kong)

2011-01-15

The rates of radial oxygen loss (ROL), root porosity, concentrations of arsenic (As), iron (Fe) and manganese (Mn) in shoot and root tissues and on root surfaces, As tolerances, and their relationships in different wetland plants were investigated based on a hydroponic experiment (control, 0.8, 1.6 mg As L{sup -1}) and a soil pot trail (control, 60 mg As kg{sup -1}). The results revealed that wetland plants showed great differences in root porosity (9-64%), rates of ROL (55-1750 mmo1 O{sub 2} kg{sup -1} root d.w. d{sup -1}), As uptake (e.g., 8.8-151 mg kg{sup -1} in shoots in 0.8 mg As L{sup -1} treatment), translocation factor (2.1-47% in 0.8 mg As L{sup -1}) and tolerance (29-106% in 0.8 mg As L{sup -1}). Wetland plants with higher rates of ROL and root porosity tended to form more Fe/Mn plaque, possess higher As tolerance, higher concentrations of As on root surfaces and a lower As translocation factor so decreasing As toxicity. - Research highlights: There is significant correlation between the porosity of roots and rates of ROL. The rates of ROL are significantly correlated with tolerance indices and concentrations of As, Fe, Mn on root surface. The rates of ROL is negatively correlated with As translocation factor. - Wetland plants with high rates of ROL tended to form more Fe plaque on root surfaces and possess higher As tolerance.

Developments in permeable and low permeability barriers

International Nuclear Information System (INIS)

Jefferis, S.A.; Norris, G.H.; Thomas, A.O.

1997-01-01

The concept of the reactive treatment zone whereby pollutants are attenuated as they move along a pathway in the ground has enabled a re-thinking of many of the concepts of containment. In particular it offers the potential for the control of the flux from a contaminated area by controlling the contaminant concentration in the pathway(s) as well as or instead of using a low permeability barrier. The paper outlines the basic concepts of the reactive treatment zone and the use of permeable and low permeability reactive systems. The paper then gives a case history of the installation of a permeable barrier using an in-situ reaction chamber

Evaluation of five strategies to limit the impact of fouling in permeable reactive barriers

International Nuclear Information System (INIS)

Li Lin; Benson, Craig H.

2010-01-01

Ground water flow and geochemical reactive transport models were used to assess the effectiveness of five strategies used to limit fouling and to enhance the long-term hydraulic behavior of continuous-wall permeable reactive barriers (PRBs) employing granular zero valent iron (ZVI). The flow model accounted for geological heterogeneity and the reactive transport model included a geochemical algorithm for simulating iron corrosion and mineral precipitation reactions that have been observed in ZVI PRBs. The five strategies that were evaluated are pea gravel equalization zones, a sacrificial pre-treatment zone, pH adjustment, large ZVI particles, and mechanical treatment. Results of simulations show that installation of pea gravel equalization zones results in flow equalization and a more uniform distribution of residence times within the PRB. Residence times within the PRB are less affected by mineral precipitation when a pre-treatment zone is employed. pH adjustment limits the total amount of hydroxide ions in ground water to reduce porosity reduction and to retain larger residence times. Larger ZVI particles reduce porosity reduction as a result of the smaller iron surface area for iron corrosion, and retain longer residence time. Mechanical treatment redistributes the porosity uniformly throughout the PRB over time, which is effective in maintaining residence time.

Effect of High Porosity Screen on the Near Wake of a Circular Cylinder

Directory of Open Access Journals (Sweden)

Sahin B.

2013-04-01

Full Text Available The change in flow characteristics downstream of a circular cylinder (inner cylinder surrounded by a permeable cylinder (outer cylinder made of a high porosity screen was investigated in shallow water using Particle Image Velocimetry (PIV technique. The diameter of the inner cylinder, outer cylinder and the water height were kept constant during the experiments as d = 50 mm, D = 100 mm and hw = 50 mm, respectively. The depth-averaged free stream velocity was also kept constant as U = 180 mm/s which corresponded to a Reynolds number of Red = 9000 based on the inner cylinder diameter. It was shown that the outer permeable cylinder had a substantialeffect on the vortex formation and consequent vortex shedding downstream of the circular cylinder, especially in the near wake. The time averaged vorticity layers, streamlines and velocity vector field depict that the location of the interaction of vortices considerably changed by the presence of the outer cylinder. Turbulent statistics clearly demonstrated that in comparison to the natural cylinder, turbulent kinetic energy and Reynolds stresses decreased remarkably downstream of the inner cylinder. Moreover, spectra of streamwise velocity fluctuations showed that the vortex shedding frequency significantly reduced compared to the natural cylinder case.

Density and permeability of a loess soil: long-term organic matter effect and the response to compressive stress

DEFF Research Database (Denmark)

Arthur, Emmanuel; Schjønning, Per; Møldrup, Per

2013-01-01

to compressive stress, undisturbed soil cores were collected from a long-term fertilisation experiment in Bad Lauchstädt in Germany, including combinations of animal manure and mineral fertilisers. The cores were drained to -100 hPa matric potential and exposed to uniaxial confined compression (200k......Pa). Investigated indicators for compression resistance included compression index, precompression stress, and resistance and resilience indices based on measured soil physical properties (bulk density, air-filled porosity, air permeability, and void ratio). Soil resilience was assessed following exposure...... but the correlation was not significant. However, initial bulk density (ρbi) and initial gravimetric water content (wi) were significantly positively correlated to the indices of soil compression resistance, with the effect of ρbi being significantly stronger. Significant recovery of airfilled porosity and air...

Characterization of aquifer heterogeneity using Cyclostratigraphy and geophysical methods in the upper part of the Karstic Biscayne Aquifer, Southeastern Florida

Science.gov (United States)

Cunningham, Kevin J.; Carlson, Janine L.; Wingard, G. Lynn; Robinson, Edward; Wacker, Michael A.

2004-01-01

This report identifies and characterizes candidate ground-water flow zones in the upper part of the shallow, eogenetic karst limestone of the Biscayne aquifer in the Lake Belt area of north-central Miami-Dade County using cyclostratigraphy, ground-penetrating radar (GPR), borehole geophysical logs, and continuously drilled cores. About 60 miles of GPR profiles were used to calculate depths to shallow geologic contacts and hydrogeologic units, image karst features, and produce qualitative views of the porosity distribution. Descriptions of the lithology, rock fabrics, and cyclostratigraphy, and interpretation of depositional environments of 50 test coreholes were linked to the geophysical interpretations to provide an accurate hydrogeologic framework. Molluscan and benthic foraminiferal paleontologic constraints guided interpretation of depositional environments represented by rockfabric facies. Digital borehole images were used to characterize and quantify large-scale vuggy porosity. Preliminary heat-pulse flowmeter data were coupled with the digital borehole image data to identify candidate ground-water flow zones. Combined results show that the porosity and permeability of the karst limestone of the Biscayne aquifer have a highly heterogeneous and anisotropic distribution that is mostly related to secondary porosity overprinting vertical stacking of rock-fabric facies within high-frequency cycles (HFCs). This distribution of porosity produces a dual-porosity system consisting of diffuse-carbonate and conduit flow zones. The nonuniform ground-water flow in the upper part of the Biscayne aquifer is mostly localized through secondary permeability, the result of solution-enlarged carbonate grains, depositional textures, bedding planes, cracks, root molds, and paleokarst surfaces. Many of the resulting pore types are classified as touching vugs. GPR, borehole geophysical logs, and whole-core analyses show that there is an empirical relation between formation porosity

3D seismic modeling in geothermal reservoirs with a distribution of steam patch sizes, permeabilities and saturations, including ductility of the rock frame

Science.gov (United States)

Carcione, José M.; Poletto, Flavio; Farina, Biancamaria; Bellezza, Cinzia

2018-06-01

Seismic propagation in the upper part of the crust, where geothermal reservoirs are located, shows generally strong velocity dispersion and attenuation due to varying permeability and saturation conditions and is affected by the brittleness and/or ductility of the rocks, including zones of partial melting. From the elastic-plastic aspect, the seismic properties (seismic velocity, quality factor and density) depend on effective pressure and temperature. We describe the related effects with a Burgers mechanical element for the shear modulus of the dry-rock frame. The Arrhenius equation combined to the octahedral stress criterion define the Burgers viscosity responsible of the brittle-ductile behaviour. The effects of permeability, partial saturation, varying porosity and mineral composition on the seismic properties is described by a generalization of the White mesoscopic-loss model to the case of a distribution of heterogeneities of those properties. White model involves the wave-induced fluid flow attenuation mechanism, by which seismic waves propagating through small-scale heterogeneities, induce pressure gradients between regions of dissimilar properties, where part of the energy of the fast P-wave is converted to slow P (Biot)-wave. We consider a range of variations of the radius and size of the patches and thin layers whose probability density function is defined by different distributions. The White models used here are that of spherical patches (for partial saturation) and thin layers (for permeability heterogeneities). The complex bulk modulus of the composite medium is obtained with the Voigt-Reuss-Hill average. Effective pressure effects are taken into account by using exponential functions. We then solve the 3D equation of motion in the space-time domain, by approximating the White complex bulk modulus with that of a set of Zener elements connected in series. The Burgers and generalized Zener models allows us to solve the equations with a direct grid

Monte Carlo simulation of determining porosity by using dual gamma detectors

International Nuclear Information System (INIS)

Zhang Feng; Liu Juntao; Yu Huawei; Yuan Chao; Jia Yan

2013-01-01

Current formation elements spectroscopy logging technology utilize 241 Am-Be neutron source and single BGO detector to determine elements contents. It plays an important role in mineral analysis and lithology identification of unconventional oil and gas exploration, but information measured is relatively ld. Measured system based on 241 Am-Be neutron and dual detectors can be developed to realize the measurement of elements content as well as determine neutron gamma porosity by using ratio of gamma count between near and far detectors. Calculation model is built by Monte Carlo method to study neutron gamma porosity logging response with different spacing and shields. And it is concluded that measuring neutron gamma have high counts and good statistical property contrasted with measuring thermal neutron, but the sensitivity of porosity decrease. Sensitivity of porosity will increase as the spacing of dual detector increases. Spacing of far and near detectors should be around 62 cm and 35 cm respectively. Gamma counts decrease and neutron gamma porosity sensitivity increase when shield is fixed between neutron and detector. The length of main shield should be greater than 10 cm and associated shielding is about 5 cm. By Monte Carlo Simulation study, the result provides technical support for determining porosity in formation elements spectroscopy logging using 241 Am-Be neutron and gamma detectors. (authors)

Low permeability Neogene lithofacies in Northern Croatia as potential unconventional hydrocarbon reservoirs

Science.gov (United States)

Malvić, Tomislav; Sučić, Antonija; Cvetković, Marko; Resanović, Filip; Velić, Josipa

2014-06-01

We present two examples of describing low permeability Neogene clastic lithofacies to outline unconventional hydrocarbon lithofacies. Both examples were selected from the Drava Depression, the largest macrostructure of the Pannonian Basin System located in Croatia. The first example is the Beničanci Field, the largest Croatian hydrocarbon reservoir discovered in Badenian coarse-grained clastics that consists mostly of breccia. The definition of low permeability lithofacies is related to the margins of the existing reservoir, where the reservoir lithology changed into a transitional one, which is mainly depicted by the marlitic sandstones. However, calculation of the POS (probability of success of new hydrocarbons) shows critical geological categories where probabilities are lower than those in the viable reservoir with proven reserves. Potential new hydrocarbon volumes are located in the structural margins, along the oil-water contact, with a POS of 9.375%. These potential reserves in those areas can be classified as probable. A second example was the Cremušina Structure, where a hydrocarbon reservoir was not proven, but where the entire structure has been transferred onto regional migration pathways. The Lower Pontian lithology is described from well logs as fine-grained sandstones with large sections of silty or marly clastics. As a result, the average porosity is low for conventional reservoir classification (10.57%). However, it is still an interesting case for consideration as a potentially unconventional reservoir, such as the "tight" sandstones.

Crustal permeability

Science.gov (United States)

Gleeson, Tom; Ingebritsen, Steven E.

2016-01-01

Permeability is the primary control on fluid flow in the Earth’s crust and is key to a surprisingly wide range of geological processes, because it controls the advection of heat and solutes and the generation of anomalous pore pressures.  The practical importance of permeability – and the potential for large, dynamic changes in permeability – is highlighted by ongoing issues associated with hydraulic fracturing for hydrocarbon production (“fracking”), enhanced geothermal systems, and geologic carbon sequestration.  Although there are thousands of research papers on crustal permeability, this is the first book-length treatment.  This book bridges the historical dichotomy between the hydrogeologic perspective of permeability as a static material property and the perspective of other Earth scientists who have long recognized permeability as a dynamic parameter that changes in response to tectonism, fluid production, and geochemical reactions. 

Relationship between petrographic pore types and core measurements in sandstones of the Monserrate Formation, upper Magdalena Valley, Colombia

International Nuclear Information System (INIS)

Ehrlich, R; Cobaleda, G; Barclay, Ferm

1997-01-01

Patterns of porosity in sandstones of the Monserrate Formation (Upper Magdalena Valley) exposed in polished blocks have been digitally recorded using an image processor coupled to a scanning electron microscope operated in back scatter electron mode. Additionally, porosity, permeability and response to mercury injection-capillary pressure tests were measured on some of the imaged samples. Porosity pattern were evaluated via an erosion/dilation-differencing image-processing algorithm and then classified by the self-training classifier, SAWVEC. Changes in the resulting pore type proportions were strongly associated with changes in the mercury porosimetry curves. From the image processing data, five pore types, sufficient to include all of the variability in size and shape of the patterns of porosity, were identified. Variations in the number of pares of each type per unit cross sectional area were related to variations in permeability. The resultant relationships with mercury porosimetry demonstrated that pares of the same type tends to form microcircuits characterized by a limited throat size range. Permeability modeling showed that intergranular Pare Types 2 and 4 (secondary porosity resulting from carbonate dissolution) are responsible for permeability in the 0,01 - 0,1 0 Darcy range. Type 5 pares (large molds) slightly contribute to permeability, except in coarse grained rocks where they are efficiently connected by micro fractures

Measurement of the porosity of amorphous materials by gamma ray transmission methodology

International Nuclear Information System (INIS)

Pottker, Walmir Eno; Appoloni, Carlos Roberto

2000-01-01

In this work it is presented the measurement of the total porosity of TRe soil, Sandstone Berea rocks and porous ceramics samples. For the determination of the total porosity, the Arquimedes method (conventional) and the gamma ray transmission methodology were employed. The porosity measurement using the gamma methodology has a significant advantage respect to the conventional method due to the fast and non-destructive determination, and also for supplying results with a greater characterization in small scales, in relation to the heterogeneity of the porosity. The conventional methodology presents good results only for homogeneous samples. The experimental set up for the gamma ray transmission technique consisted of a 241 Am source (59,53 keV ), a NaI(Tl) scintillation detector, collimators, a XYZ micrometric table and standard gamma spectrometry electronics connected to a multichannel analyser. (author)

Application of MRIL-WD (Magnetic Resonance Imaging Logging While Drilling) for irreducible water saturation, total reservoir, free-fluid, bound-fluid porosity measurements and its value for the petrophysical analysis of RT/RM data from the Shah Deniz well

Science.gov (United States)

Amirov, Elnur

2016-04-01

, preferably while the drilling of the brand new wells (logging-while-drilling, LWD). The MRIL-WD Tool can accomplish any tasks reliably and in a timely manner thus saving drilling time and reducing the overall risk for the well. Control of water production and identification of pay zones with high irreducible water saturation are also very important for formation evaluation and petrophysical analysis in oil fields located in the Azerbaijan Republic and also other fields around the world. Sometimes above-mentioned problems can cause delay in completion decisions which will create additional expenses for field management. In many wells, breakthroughs in reservoir characterization have been achieved in directly determining hydrocarbon volumes, net permeability thickness, and hydrocarbon type, thus circumventing the problems associated with obtaining wireline data and the considerable amount of rig time required (so MRIL-WD can considerably reduce the NPT). Some reservoir zones with relatively low water saturation, which calculated from the other conventional logs, can produce with relatively high percentage of water cut, primarily because much of the water is movable. However, other zones with high calculated water saturation produce water free hydrocarbons. The difficulty in predicting water production can be related with the producing from the complex lithology, which can contain low-permeability, medium- to fine-grained shaly sands. Where grains are small, the formations have high surface to volume ratios that result in high irreducible water saturation and due to this we can see low resistivity values. As a result the use of resistivity logs as pay indicator, sometimes can cause low resistivity pay zones might be overlooked and consequently net field pay could be underestimated. In the last few years, nuclear magnetic resonance logs have shown great promise in solving problems of formation evaluation that could not be directly resolved with conventional logs. The capability

DECOVALEX-THMC Task D: Long-Term Permeability/Porosity Changes in the EDZ and Near Field due to THM and THC Processes in Volcanic and Crystalline-Bentonite Systems, Status Report October 2005

International Nuclear Information System (INIS)

Birkholzer, J.; Rutqvist, J.; Sonnenthal, E.; Barr, D.

2005-01-01

The DECOVALEX project is an international cooperative project initiated by SKI, the Swedish Nuclear Power Inspectorate, with participation of about 10 international organizations. The name DECOVALEX stands for DEvelopment of COupled models and their VALidation against Experiments. The general goal of this project is to encourage multidisciplinary interactive and cooperative research on modeling coupled processes in geologic formations in support of the performance assessment for underground storage of radioactive waste. Three multi-year project stages of DECOVALEX have been completed in the past decade, mainly focusing on coupled thermal-hydrological-mechanical processes. Currently, a fourth three-year project stage of DECOVALEX is under way, referred to as DECOVALEX-THMC. THMC stands for Thermal, Hydrological, Mechanical, and Chemical processes. The new project stage aims at expanding the traditional geomechanical scope of the previous DECOVALEX project stages by incorporating geochemical processes important for repository performance. The U.S. Department of Energy (DOE) leads Task D of the new DECOVALEX phase, entitled ''Long-term Permeability/Porosity Changes in the EDZ and Near Field due to THC and THM Processes for Volcanic and Crystalline-Bentonite Systems''. In its leadership role for Task D, DOE coordinates and sets the direction for the cooperative research activities of the international research teams engaged in Task D

The porosity formation mechanism in the laser-MIG hybrid welded joint of Invar alloy

Science.gov (United States)

Zhan, Xiaohong; Gao, Qiyu; Gu, Cheng; Sun, Weihua; Chen, Jicheng; Wei, Yanhong

2017-10-01

The porosity formation mechanism in the laser-metal inter gas (MIG) multi-layer hybrid welded (HW) joint of 19.05 mm thick Invar alloy is investigated. The microstructure characteristics and energy dispersive spectroscopy (EDS) are analyzed. The phase identification was conducted by the X-ray diffractometer (XRD). Experimental results show that the generation of porosity is caused by the relatively low laser power in the root pass and low current in the cover pass. It is also indicated that the microstructures of the welded joints are mainly observed to be columnar crystal and equiaxial crystal, which are closely related to the porosity formation. The EDS results show that oxygen content is significantly high in the inner wall of the porosity. The XRD results indicate that the BM and the WB of laser-MIG HW all are composed of Fe0.64Ni0.36 and γ-(Fe,Ni). When the weld pool is cooled quickly, [NiO] [FeO] and [MnO] are formed that react on C to generate CO/CO2 gases. The porosity of laser-MIG HW for Invar alloy is oxygen pore. The root source of metallurgy porosity formation is that the dissolved gases are hard to escape sufficiently and thus exist in the weld pool. Furthermore, 99.99% pure Argon is recommended as protective gas in the laser-MIG HW of Invar alloy.

Cold spray NDE for porosity and other process anomalies

Science.gov (United States)

Glass, S. W.; Larche, M. R.; Prowant, M. S.; Suter, J. D.; Lareau, J. P.; Jiang, X.; Ross, K. A.

2018-04-01

This paper describes a technology review of nondestructive evaluation (NDE) methods that can be applied to cold spray coatings. Cold spray is a process for depositing metal powder at high velocity so that it bonds to the substrate metal without significant heating that would be likely to cause additional residual tensile stresses. Coatings in the range from millimeters to centimeters are possible at relatively high deposition rates. Cold spray coatings that may be used for hydroelectric components that are subject to erosion, corrosion, wear, and cavitation damage are of interest. The topic of cold spray NDE is treated generally, however, but may be considered applicable to virtually any cold spray application except where there are constraints of the hydroelectric component application that bear special consideration. Optical profilometry, eddy current, ultrasound, and hardness tests are shown for one set of good, fair, and poor nickel-chrome (NiCr) on 304 stainless steel (304SS) cold spray samples to demonstrate inspection possibilities. The primary indicator of cold spray quality is the cold spray porosity that is most directly measured with witness-sample destructive examinations (DE)—mostly photo-micrographs. These DE-generated porosity values are correlated with optical profilometry, eddy current, ultrasound, and hardness test NDE methods to infer the porosity and other information of interest. These parameters of interest primarily include: • Porosity primarily caused by improper process conditions (temperature, gas velocity, spray standoff, spray angle, powder size, condition, surface cleanliness, surface oxide, etc.) • Presence/absence of the cold spray coating including possible over-sprayed voids • Coating thicknessOptical profilometry measurements of surface roughness trended with porosity plus, if compared with a reference measurement or reference drawing, would provide information on the coating thickness. Ultrasound could provide similar

Optimization of High Porosity Thermal Barrier Coatings Generated with a Porosity Former

Science.gov (United States)

Medřický, Jan; Curry, Nicholas; Pala, Zdenek; Vilemova, Monika; Chraska, Tomas; Johansson, Jimmy; Markocsan, Nicolaie

2015-04-01

Yttria-stabilized zirconia thermal barrier coatings are extensively used in turbine industry; however, increasing performance requirements have begun to make conventional air plasma sprayed coatings insufficient for future needs. Since the thermal conductivity of bulk material cannot be lowered easily; the design of highly porous coatings may be the most efficient way to achieve coatings with low thermal conductivity. Thus the approach of fabrication of coatings with a high porosity level based on plasma spraying of ceramic particles of dysprosia-stabilized zirconia mixed with polymer particles, has been tested. Both polymer and ceramic particles melt in plasma and after impact onto a substrate they form a coating. When the coating is subjected to heat treatment, polymer burns out and a complex structure of pores and cracks is formed. In order to obtain desired porosity level and microstructural features in coatings; a design of experiments, based on changes in spray distance, powder feeding rate, and plasma-forming atmosphere, was performed. Acquired coatings were evaluated for thermal conductivity and thermo-cyclic fatigue, and their morphology was assessed using scanning electron microscopy. It was shown that porosity level can be controlled by appropriate changes in spraying parameters.

Theoretical Insight Into the Empirical Tortuosity-Connectivity Factor in the Burdine-Brooks-Corey Water Relative Permeability Model

Science.gov (United States)

Ghanbarian, Behzad; Ioannidis, Marios A.; Hunt, Allen G.

2017-12-01

A model commonly applied to the estimation of water relative permeability krw in porous media is the Burdine-Brooks-Corey model, which relies on a simplified picture of pores as a bundle of noninterconnected capillary tubes. In this model, the empirical tortuosity-connectivity factor is assumed to be a power law function of effective saturation with an exponent (μ) commonly set equal to 2 in the literature. Invoking critical path analysis and using percolation theory, we relate the tortuosity-connectivity exponent μ to the critical scaling exponent t of percolation that characterizes the power law behavior of the saturation-dependent electrical conductivity of porous media. We also discuss the cause of the nonuniversality of μ in terms of the nonuniversality of t and compare model estimations with water relative permeability from experiments. The comparison supports determining μ from the electrical conductivity scaling exponent t, but also highlights limitations of the model.

Measurement of choroid plexus perfusion using dynamic susceptibility MR imaging: capillary permeability and age-related changes

Energy Technology Data Exchange (ETDEWEB)

Bouzerar, Roger; Chaarani, Bader; Baledent, Olivier [University Hospital, Image Processing Department, Amiens (France); Gondry-Jouet, Catherine [University Hospital, Radiology Department, Amiens (France); Zmudka, Jadwiga [University Hospital, Geriatric Unit, Amiens (France)

2013-12-15

The cerebrospinal fluid (CSF) plays a major role in the physiology of the central nervous system. The continuous turnover of CSF is mainly attributed to the highly vascularized choroid plexus (CP) located in the cerebral ventricles which represent a complex interface between blood and CSF. We propose a method for evaluating CP functionality in vivo using perfusion MR imaging and establish the age-related changes of associated parameters. Fifteen patients with small intracranial tumors were retrospectively studied. MR Imaging was performed on a 3T MR Scanner. Gradient-echo echo planar images were acquired after bolus injection of gadolinium-based contrast agent (CA). The software developed used the combined T1- and T2-effects. The decomposition of the relaxivity signals enables the calculation of the CP capillary permeability (K{sub 2}). The relative cerebral blood volume (rCBV), mean transit time (MTT), and signal slope decrease (SSD) were also calculated. The mean permeability K{sub 2} of the extracted CP was 0.033+/-0.18 s{sup -1}. K{sub 2} and SSD significantly decreased with subject's age whereas MTT significantly increased with subject's age. No significant correlation was found for age-related changes in rCBV and rCBF. The decrease in CP permeability is in line with the age-related changes in CSF secretion observed in animals. The MTT increase indicates significant structural changes corroborated by microscopy studies in animals or humans. Overall, DSC MR-perfusion enables an in vivo evaluation of the hemodynamic state of CP. Clinical applications such as neurodegenerative diseases could be considered thanks to specific functional studies of CP. (orig.)

On the field determination of effective porosity

International Nuclear Information System (INIS)

Javandel, I.

1989-03-01

Effective porosity of geologic materials is a very important parameter for estimating groundwater travel time and modeling contaminant transport in hydrologic systems. Determination of a representative effective porosity for nonideal systems is a problem still challenging hydrogeologists. In this paper, some of the conventional field geophysical and hydrological methods for estimating effective porosity of geologic materials are reviewed. The limitations and uncertainties associated with each method are discussed. 30 refs., 8 figs

Flow around a cylinder surrounded by a permeable cylinder in shallow water

Energy Technology Data Exchange (ETDEWEB)

Ozkan, Gokturk M.; Akilli, Huseyin; Sahin, Besir [Cukurova University, Department of Mechanical Engineering, Faculty of Engineering and Architecture, Adana (Turkey); Oruc, Vedat [Dicle University, Department of Mechanical Engineering, Diyarbakir (Turkey)

2012-12-15

The change in flow characteristics downstream of a circular cylinder (inner cylinder) surrounded by an outer permeable cylinder was investigated in shallow water using particle image velocimetry technique. The diameter of the inner cylinder and the water height were kept constant during the experiments as d=50 mm and h{sub w}=25 mm, respectively. The depth-averaged free-stream velocity was also kept constant as U=170 mm/s which corresponded to a Reynolds number of Re{sub d}=8,500 based on the inner cylinder diameter. In order to examine the effect of diameter and porosity of the outer cylinder on flow characteristics of the inner cylinder, five different outer cylinder diameters (D=60, 70, 80, 90 and 100 mm) and four different porosities ({beta}=0.4, 0.5, 0.6 and 0.7) were used. It was shown that both porosity and outer cylinder diameter had a substantial effect on the flow characteristics downstream of the circular cylinder. Turbulent statistics clearly demonstrated that in comparison with the bare cylinder (natural case), turbulent kinetic energy and Reynolds stresses decreased remarkably when an outer cylinder was placed around the inner cylinder. Thereby, the interaction of shear layers of the inner cylinder has been successfully prevented by the presence of outer cylinder. It was suggested by referring to the results that the outer cylinder having 1.6{<=}D/d{<=}2.0 and 0.4{<=}D/d{<=}0.6 should be preferred to have a better flow control in the near wake since the peak magnitude of turbulent kinetic energy was considerably low in comparison with the natural case and it was nearly constant for these mentioned porosities {beta}, and outer cylinder to inner cylinder diameter ratios D/d. (orig.)

Unconfined versus confined speleogenetic settings: variations of solution porosity.

Directory of Open Access Journals (Sweden)

Klimchouk Alexander

2006-01-01

Full Text Available Speleogenesis in confined settings generates cave morphologies that differ much from those formed in unconfined settings. Cavesdeveloped in unconfined settings are characterised by broadly dendritic patterns of channels due to highly competing development.In contrast, caves originated under confined conditions tend to form two- or three-dimensional mazes with densely packed conduits.This paper illustrates variations of solution (channel porosity resulted from speleogenesis in unconfined and confined settings by theanalysis of morphometric parameters of typical cave patterns. Two samples of typical cave systems formed in the respective settingsare compared. The sample that represents unconfined speleogenesis consists of solely limestone caves, whereas gypsum cavesof this type tend to be less dendritic and more linear. The sample that represents confined speleogenesis consists of both limestoneand gypsum maze caves. The comparison shows considerable differences in average values of some parameters between thesettings. Passage network density (the ratio of the cave length to the area of the cave field, km/km2 is one order of magnitudegreater in confined settings than in unconfined (average 167.3 km/km2 versus 16.6 km/km2. Similarly, an order of magnitudedifference is observed in cave porosity (a fraction of the volume of a cave block, occupied by mapped cavities; 5.0 % versus 0.4 %.This illustrates that storage in maturely karstified confined aquifers is generally much greater than in unconfined. The average areal coverage (a fraction of the area of the cave field occupied by passages in a plan view is about 5 times greater in confined settingsthan in unconfined (29.7 % versus 6.4 %. This indicates that conduit permeability in confined aquifers is appreciably easier to targetwith drilling than the widely spaced conduits in unconfined aquifers.

Evaluation of single- and dual-porosity models for reproducing the release of external and internal tracers from heterogeneous waste-rock piles.

Science.gov (United States)

Blackmore, S; Pedretti, D; Mayer, K U; Smith, L; Beckie, R D

2018-05-30

Accurate predictions of solute release from waste-rock piles (WRPs) are paramount for decision making in mining-related environmental processes. Tracers provide information that can be used to estimate effective transport parameters and understand mechanisms controlling the hydraulic and geochemical behavior of WRPs. It is shown that internal tracers (i.e. initially present) together with external (i.e. applied) tracers provide complementary and quantitative information to identify transport mechanisms. The analysis focuses on two experimental WRPs, Piles 4 and Pile 5 at the Antamina Mine site (Peru), where both an internal chloride tracer and externally applied bromide tracer were monitored in discharge over three years. The results suggest that external tracers provide insight into transport associated with relatively fast flow regions that are activated during higher-rate recharge events. In contrast, internal tracers provide insight into mechanisms controlling solutes release from lower-permeability zones within the piles. Rate-limited diffusive processes, which can be mimicked by nonlocal mass-transfer models, affect both internal and external tracers. The sensitivity of the mass-transfer parameters to heterogeneity is higher for external tracers than for internal tracers, as indicated by the different mean residence times characterizing the flow paths associated with each tracer. The joint use of internal and external tracers provides a more comprehensive understanding of the transport mechanisms in WRPs. In particular, the tracer tests support the notion that a multi-porosity conceptualization of WRPs is more adequate for capturing key mechanisms than a dual-porosity conceptualization. Copyright © 2018 Elsevier B.V. All rights reserved.

Determination of Porosity in Shale by Double Headspace Extraction GC Analysis.

Science.gov (United States)

Zhang, Chun-Yun; Li, Teng-Fei; Chai, Xin-Sheng; Xiao, Xian-Ming; Barnes, Donald

2015-11-03

This paper reports on a novel method for the rapid determination of the shale porosity by double headspace extraction gas chromatography (DHE-GC). Ground core samples of shale were placed into headspace vials and DHE-GC measurements of released methane gas were performed at a given time interval. A linear correlation between shale porosity and the ratio of consecutive GC signals was established both theoretically and experimentally by comparing with the results from the standard helium pycnometry method. The results showed that (a) the porosity of ground core samples of shale can be measured within 30 min; (b) the new method is not significantly affected by particle size of the sample; (c) the uncertainties of measured porosities of nine shale samples by the present method range from 0.31 to 0.46 p.u.; and (d) the results obtained by the DHE-GC method are in a good agreement with those from the standard helium pycnometry method. In short, the new DHE-GC method is simple, rapid, and accurate, making it a valuable tool for shale gas-related research and applications.

Method and apparatus for dual-spaced fast/epithermal neutron porosity measurements

International Nuclear Information System (INIS)

Smith, H.D. Jr.

1986-01-01

A method is described for determining the porosity of earth formations in the vicinity of a well borehole, comprising: (a) irradiating the earth formations in the vicinity of the well borehole with a continuous chemical type source of fast neutrons, (b) detecting the fast neutron population at a first shorter spaced distance from the neutron source in the borehole and generating signals representative thereof, (c) detecting the epithermal neutron population at a second space distance from the neutron source in the borehole and generating signals representative thereof, the second spaced distance being greater than the first spaced distance from the neutron source, (d) forming a ratio of the signals representing the fast and epithermal neutron populations to derive a measurement signal functionally related to the porosity of the earth formations in the vicinity of the borehole, and (e) calibrating the measurement signal according to a predetermined functional relationship to derive a porosity signal quantitatively representative of the porosity of the earth formations in the vicinity of the borehole

Predicting petrophysical properties by simultaneous inversion of seismic and reservoir engineering data

Science.gov (United States)

Mantilla, Andres Eduardo

Porosity and permeability are the most difficult properties to determine in subsurface reservoir characterization, yet usually they have the largest impact on reserves and production forecasts, and consequently on the economy of a project. The difficulty of estimating them comes from the fact that porosity and permeability may vary significantly over the reservoir volume, but can only be sampled at well locations, often using different technologies at different scales of observation. An accurate estimation of the spatial distribution of porosity and permeability is of key importance, because it translates into higher success rates in infill drilling, and fewer wells required for draining the reservoir. The purpose of this thesis is to enhance the characterization of subsurface reservoirs by improving the prediction of petrophysical properties through the combination of reservoir geophysics and reservoir engineering observations and models. To fulfill this goal, I take advantage of the influence that petrophysical properties have on seismic and production data, and formulate, implement, and demonstrate the applicability of an inversion approach that integrates seismic and production-related observations with a-priori information about porosity and permeability. Being constrained by physical models and observations, the resulting estimates are appropriate for making reservoir management decisions. I use synthetic models to test the proposed inversion approach. Results from these tests show that, because of the excellent spatial coverage of seismic data, incorporating seismic-derived attributes related to petrophysical properties can significantly improve the estimates of porosity and permeability. The results also highlight the importance of using a-priori information about the relationship between porosity and permeability. The last chapters of this thesis describe a practical application of the proposed joint inversion approach. This application includes a rock

Experimental characterization of the water transport properties of PEM fuel cells diffusion media

Science.gov (United States)

Ramos-Alvarado, Bladimir; Sole, Joshua D.; Hernandez-Guerrero, Abel; Ellis, Michael W.

2012-11-01

A full experimental characterization of the liquid water transport properties of Toray TGP-090 paper is carried out in this work. Porosity, capillary pressure curves (capillary pressure-saturation relationships), absolute permeability, and relative permeability are obtained via experimental procedures. Porosity was determined using two methods, both aimed to obtain the solid volume of the network of fibers comprising the carbon paper. Capillary pressure curves were obtained using a gas displacement porosimeter where liquid water is injected using a syringe pump and the capillary pressure is recorded using a differential pressure transducer. Absolute and relative permeability were also measured with an apparatus designed at Virginia Tech. Absolute permeability was calculated at different flow rates using nitrogen. On the other hand, relative permeability was a more complicated task to carry out giving the complexity (two-phase flow condition) of this property. All of the water transport properties of Toray TGP-090 were studied under the effects of wet-proofing (PTFE treatment) and compression. Some observations were that wet-proofing reduces the porosity of the raw material, increases the hydrophobicity (Pc-S curves), and reduces the permeability of the material. Similar effects were observed for compression, where compressed material exhibited trends similar to those of wet-proofing effects. The results presented here will allow a more accurate modeling of PEMFCs, providing an experimentally verified alternative to the assumptions frequently employed.

Porosity study on free mineral addition cement paste

International Nuclear Information System (INIS)

Salgueiro, W.; Somoza, A.; Cabrera, O.; Consolati, G.

2004-01-01

A study of the hydration process and the porosity evolution in a cement paste is presented. The analysis of porosity was made in samples with water to cement ratios (w/c) of 0.24, 0.40 and 0.60 at age of 3, 7, 28 and 365 days, respectively. Information on the evolution of total porosity and on the strength of the paste were obtained using positron annihilation lifetime spectroscopy (PALS), scanning electron microscopy (SEM), X-ray diffraction (XRD), mechanical tests (compression and flexion) and water absorption techniques. Specifically, positron lifetime technique allowed us to analyze the evolution of gel and capillary porosity during the hydration process. Using a simple function proposed, reasonable fits to the experimental data of the porosity evolution as a function of the compression strength were obtained

Effect of permeability enhancers on paracellular permeability of acyclovir.

Science.gov (United States)

Ates, Muge; Kaynak, Mustafa Sinan; Sahin, Selma

2016-06-01

According to Biopharmaceutics Classification System (BCS), acyclovir is a class III (high solubility, low permeability) compound, and it is transported through paracellular route by passive diffusion. The aim of this study was to investigate the effect of various pharmaceutical excipients on the intestinal permeability of acyclovir. The single-pass in-situ intestinal perfusion (SPIP) method was used to estimate the permeability values of acyclovir and metoprolol across different intestinal segments (jejunum, ileum and colon). Permeability coefficient (Peff ) of acyclovir was determined in the absence and presence of a permeation enhancer such as dimethyl β-cyclodextrin (DM-β-CD), sodium lauryl sulfate (SLS), sodium caprate (Cap-Na) and chitosan chloride. All enhancers increased the permeability of paracellularly transported acyclovir. Although Cap-Na has the highest permeability-enhancing effect in all segments, permeation-enhancing effect of chitosan and SLS was only significant in ileum. On the other hand, DM-β-CD slightly decreased the permeability in all intestinal segments. These findings have potential implication concerning the enhancement of absorption of paracellularly transported compounds with limited oral bioavailability. In the case of acyclovir, Cap-Na either alone or in combination with SLS or chitosan has the potential to improve its absorption and bioavailability and has yet to be explored. © 2016 Royal Pharmaceutical Society.

Primary vesicles, vesicle-rich segregation structures and recognition of primary and secondary porosities in lava flows from the Paraná igneous province, southern Brazil

Science.gov (United States)

Barreto, Carla Joana S.; de Lima, Evandro F.; Goldberg, Karin

2017-04-01

This study focuses on a volcanic succession of pāhoehoe to rubbly lavas of the Paraná-Etendeka Province exposed in a single road profile in southernmost Brazil. This work provides an integrated approach for examining primary vesicles and vesicle-rich segregation structures at the mesoscopic scale. In addition, this study provides a quantitative analysis of pore types in thin section. We documented distinct distribution patterns of vesicle and vesicle-rich segregation structures according to lava thickness. In compound pāhoehoe lavas, the cooling allows only vesicles (pipe vesicles to be frozen into place. In inflated pāhoehoe lavas, vesicles of different sizes are common, including pipe vesicles, and also segregation structures such as proto-cylinders, cylinders, cylinder sheets, vesicle sheets, and pods. In rubbly lavas, only vesicles of varying sizes occur. Gas release from melt caused the formation of primary porosity, while hydrothermal alteration and tectonic fracturing are the main processes that generated secondary porosity. Although several forms of porosity were created in the basaltic lava flows, the precipitation of secondary minerals within the pores has tended to reduce the original porosities. Late-stage fractures could create efficient channel networks for possible hydrocarbon/groundwater migration and entrapment owing to their ability to connect single pores. Quantitative permeability data should be gathered in future studies to confirm the potential of these lavas for store hydrocarbons or groundwater.

A modeling and numerical algorithm for thermoporomechanics in multiple porosity media for naturally fractured reservoirs

Science.gov (United States)

Kim, J.; Sonnenthal, E. L.; Rutqvist, J.

2011-12-01

Rigorous modeling of coupling between fluid, heat, and geomechanics (thermo-poro-mechanics), in fractured porous media is one of the important and difficult topics in geothermal reservoir simulation, because the physics are highly nonlinear and strongly coupled. Coupled fluid/heat flow and geomechanics are investigated using the multiple interacting continua (MINC) method as applied to naturally fractured media. In this study, we generalize constitutive relations for the isothermal elastic dual porosity model proposed by Berryman (2002) to those for the non-isothermal elastic/elastoplastic multiple porosity model, and derive the coupling coefficients of coupled fluid/heat flow and geomechanics and constraints of the coefficients. When the off-diagonal terms of the total compressibility matrix for the flow problem are zero, the upscaled drained bulk modulus for geomechanics becomes the harmonic average of drained bulk moduli of the multiple continua. In this case, the drained elastic/elastoplastic moduli for mechanics are determined by a combination of the drained moduli and volume fractions in multiple porosity materials. We also determine a relation between local strains of all multiple porosity materials in a gridblock and the global strain of the gridblock, from which we can track local and global elastic/plastic variables. For elastoplasticity, the return mapping is performed for all multiple porosity materials in the gridblock. For numerical implementation, we employ and extend the fixed-stress sequential method of the single porosity model to coupled fluid/heat flow and geomechanics in multiple porosity systems, because it provides numerical stability and high accuracy. This sequential scheme can be easily implemented by using a porosity function and its corresponding porosity correction, making use of the existing robust flow and geomechanics simulators. We implemented the proposed modeling and numerical algorithm to the reaction transport simulator

Experimental Studies on Permeability of Intact and Singly Jointed Meta-Sedimentary Rocks Under Confining Pressure

Science.gov (United States)

Wong, Louis Ngai Yuen; Li, Diyuan; Liu, Gang

2013-01-01

Three different types of permeability tests were conducted on 23 intact and singly jointed rock specimens, which were cored from rock blocks collected from a rock cavern under construction in Singapore. The studied rock types belong to inter-bedded meta-sandstone and meta-siltstone with very low porosity and high uniaxial compressive strength. The transient pulse water flow method was employed to measure the permeability of intact meta-sandstone under a confining pressure up to 30 MPa. It showed that the magnitude order of meta-sandstone's intrinsic permeability is about 10-18 m2. The steady-state gas flow method was used to measure the permeability of both intact meta-siltstone and meta-sandstone in a triaxial cell under different confining pressures spanning from 2.5 to 10 MPa. The measured permeability of both rock types ranged from 10-21 to 10-20 m2. The influence of a single natural joint on the permeability of both rock types was studied by using the steady-state water flow method under different confining pressures spanning from 1.25 to 5.0 MPa, including loading and unloading phases. The measured permeability of both jointed rocks ranged from 10-13 to 10-11 m2, where the permeability of jointed meta-siltstone was usually slightly lower than that of jointed meta-sandstone. The permeability of jointed rocks decreases with increasing confining pressure, which can be well fitted by an empirical power law relationship between the permeability and confining pressure or effective pressure. The permeability of partly open cracked specimens is lower than that of open cracked specimens, but it is higher than that of the specimen with a dominant vein for the meta-sandstone under the same confining pressure. The permeability of open cracked rock specimens will partially recover during the unloading confining pressure process. The equivalent crack (joint) aperture is as narrow as a magnitude order of 10-6 m (1 μm) in the rock specimens under confining pressures

Transformable ferroelectric control of dynamic magnetic permeability

Science.gov (United States)

Jiang, Changjun; Jia, Chenglong; Wang, Fenglong; Zhou, Cai; Xue, Desheng

2018-02-01

Magnetic permeability, which measures the response of a material to an applied magnetic field, is crucial to the performance of magnetic devices and related technologies. Its dynamic value is usually a complex number with real and imaginary parts that describe, respectively, how much magnetic power can be stored and lost in the material. Control of permeability is therefore closely related to energy redistribution within a magnetic system or energy exchange between magnetic and other degrees of freedom via certain spin-dependent interactions. To avoid a high power consumption, direct manipulation of the permeability with an electric field through magnetoelectric coupling leads to high efficiency and simple operation, but remains a big challenge in both the fundamental physics and material science. Here we report unambiguous evidence of ferroelectric control of dynamic magnetic permeability in a Co /Pb (Mg1/3Nb2/3) 0.7Ti0.3O3 (Co/PMN-PT) heterostructure, in which the ferroelectric PMN-PT acts as an energy source for the ferromagnetic Co film via an interfacial linear magnetoelectric interaction. The electric field tuning of the magnitude and line shape of the permeability offers a highly localized means of controlling magnetization with ultralow power consumption. Additionally, the emergence of negative permeability promises a new way of realizing functional nanoscale metamaterials with adjustable refraction index.

Diagenetic controls on porosity variations within an aeolian sandstone reservoir, borehole Kudu 9A-3

International Nuclear Information System (INIS)

Marot, J.E.B.

1990-01-01

Three boreholes, Kudu 9A-1, 9A-2 and 9A-3, were drilled approximately 125 km west of the Orange River mouth to test a gas-bearing structure of Barremian age. The reservoir interval comprises an upper unit of interbedded shallow marine sandstones, limestones and volcaniclastic mass flow deposits, and a lower non-marine unit of interbedded aeolian sandstones, basaltic lavas and volcaniclastic deposits. Despite the overall good poroperm characteristics of the aeolian sandstone and its apparent mineralogical homogeneity, as implied by a gamma ray trace, the core analysis results show an extreme variation in porosity and permeability values. In order to assist in reservoir quality prediction and to assess the regional prospectivity of the sandstone, it was necessary to explain these variations. The resuls of the study indicate that compositionally and texturally the sandstones are extremely homogeneous. It is concluded that the marked variation in the poroperm characteristics of the aeolian sandstones is a result of a relatively complex diagenesis. A fluctuating water table resulted in the formation of a pattern of calcite, anhydrite and quartz cements within an aeolian dune sandstone. 7 refs., 1 fig

Particle track membranes with higher porosity

International Nuclear Information System (INIS)

Heinrich, B.; Gemende, B.; Lueck, H.B.

1992-01-01

Possibilities of improvement of flux and dirt loading capacity of particle track membranes have been examined. Three different ways were investigated: using a divergent ion beam for the irradiation; enlarging the surface porosity through a conical pore shape; creating an asymmetrical membrane structure with two different porosities. Mathematical models and experimental results have been discussed. 9 figs, 3 tabs

Ultrasonic velocities of North Sea chalk samples: influence of porosity, fluid content and texture

DEFF Research Database (Denmark)

Rogen, B.; Fabricius, Ida Lykke; Japsen, P.

2005-01-01

a porosity-reducing effect and that samples rich in large grains have a relatively low porosity for a given P-wave modulus. The clay content in the samples is low and is mainly represented by either kaolinite or smectite; samples with smectite have a lower P-wave modulus than samples with kaolinite at equal...

The influence of slip velocity and temperature on permeability during and after high-velocity fault slip

Science.gov (United States)

Tanikawa, W.; Mukoyoshi, H.; Tadai, O.; Hirose, T.; Lin, W.

2011-12-01

Fluid transport properties in fault zones play an important role in dynamic processes during large earthquakes. If the permeability in a fault zone is low, high pore-fluid pressures caused by thermal pressurization (Sibson, 1973) or shear-induced compaction (Blanpied et al., 1992) can lead to an apparent reduction of fault strength. Changes in porosity and permeability of fault rocks within a fault zone during earthquakes and the subsequent progressive recovery of these properties may have a large influence on earthquake recurrence (Sleep and Blanpied, 1992). A rotary shear apparatus was used to investigate changes of fluid transport properties in a fault zone by real-time measurement of gas flow rates during and after shearing of hollow sandstone and granite cylinders at various slip rates. Our apparatus measures permeability parallel to the slip plane in both the slip zone and wall rocks. In all cases, permeability decreased rapidly with an increase of friction, but recovered soon after slip, reaching a steady state within several tens of minutes. The rate of reduction of permeability increased with increasing slip velocity. Permeability did not recover to pre-slip levels after low-velocity tests but recovered to exceed them after high-velocity tests. Frictional heating of gases at the slip surface increased gas viscosity, which increased gas flow rate to produce an apparent permeability increase. The irreversible permeability changes of the low-velocity tests were caused by gouge formation due to wearing and smoothing of the slip surface. The increase of permeability after high-velocity tests was caused by mesoscale fracturing in response to rapid temperature rise. Changes of pore fluid viscosity contributed more to changes of flow rate than did permeability changes caused by shear deformation, although test results from different rocks and pore fluids might be different. References Blanpied, M.L., Lockner, D.A., Byerlee, J.D., 1992. An earthquake mechanism

Porosity Assessment for Different Diameters of Coir Lignocellulosic Fibers

Science.gov (United States)

da Luz, Fernanda Santos; Paciornik, Sidnei; Monteiro, Sergio Neves; da Silva, Luiz Carlos; Tommasini, Flávio James; Candido, Verônica Scarpini

2017-10-01

The application of natural lignocellulosic fibers (LCFs) in engineering composites has increased interest in their properties and structural characteristics. In particular, the inherent porosity of an LCF markedly affects its density and the adhesion to polymer matrices. For the first time, both open and closed porosities of a natural LCF, for different diameter ranges, were assessed. Fibers extracted from the mesocarp of the coconut fruit were investigated by nondestructive methods of density measurements and x-ray microtomography (microCT). It was found that, for all diameter ranges, the closed porosity is significantly higher than the open porosity. The total porosity increases with diameter to around 60% for coir fibers with more than 503 μm in diameter. The amount and characteristics of these open and closed porosities were revealed by t test and Weibull statistics as well as by microCT.

Air filled porosity in composting processes

Energy Technology Data Exchange (ETDEWEB)

Ruggieri, L.; Gea, T.; Artola, A.; Sanchez, A.

2009-07-01

As it is widely known, the composting process consists in the aerobic decomposition of the biodegradable organic matter present in different types of solid wastes. Water and oxygen are necessary for the biological activity of microorganisms involved in the composting process and their availability is directly related to the total and the air filled porosity (AFP). Maintaining adequate AFP level satisfies the oxygen content requirement to achieve the desired composting conditions and thus, tho enhance biological activity. (Author)

Air filled porosity in composting processes

International Nuclear Information System (INIS)

Ruggieri, L.; Gea, T.; Artola, A.; Sanchez, A.

2009-01-01

As it is widely known, the composting process consists in the aerobic decomposition of the biodegradable organic matter present in different types of solid wastes. Water and oxygen are necessary for the biological activity of microorganisms involved in the composting process and their availability is directly related to the total and the air filled porosity (AFP). Maintaining adequate AFP level satisfies the oxygen content requirement to achieve the desired composting conditions and thus, tho enhance biological activity. (Author)

Reservoir characterization of the Mt. Simon Sandstone, Illinois Basin, USA

Science.gov (United States)

Frailey, S.M.; Damico, J.; Leetaru, H.E.

2011-01-01

The integration of open hole well log analyses, core analyses and pressure transient analyses was used for reservoir characterization of the Mt. Simon sandstone. Characterization of the injection interval provides the basis for a geologic model to support the baseline MVA model, specify pressure design requirements of surface equipment, develop completion strategies, estimate injection rates, and project the CO2 plume distribution.The Cambrian-age Mt. Simon Sandstone overlies the Precambrian granite basement of the Illinois Basin. The Mt. Simon is relatively thick formation exceeding 800 meters in some areas of the Illinois Basin. In the deeper part of the basin where sequestration is likely to occur at depths exceeding 1000 m, horizontal core permeability ranges from less than 1 ?? 10-12 cm 2 to greater than 1 ?? 10-8 cm2. Well log and core porosity can be up to 30% in the basal Mt. Simon reservoir. For modeling purposes, reservoir characterization includes absolute horizontal and vertical permeability, effective porosity, net and gross thickness, and depth. For horizontal permeability, log porosity was correlated with core. The core porosity-permeability correlation was improved by using grain size as an indication of pore throat size. After numerous attempts to identify an appropriate log signature, the calculated cementation exponent from Archie's porosity and resistivity relationships was used to identify which porosity-permeability correlation to apply and a permeability log was made. Due to the relatively large thickness of the Mt. Simon, vertical permeability is an important attribute to understand the distribution of CO2 when the injection interval is in the lower part of the unit. Only core analyses and specifically designed pressure transient tests can yield vertical permeability. Many reservoir flow models show that 500-800 m from the injection well most of the CO2 migrates upward depending on the magnitude of the vertical permeability and CO2 injection

Black bears with longer disuse (hibernation) periods have lower femoral osteon population density and greater mineralization and intracortical porosity.

Science.gov (United States)

Wojda, Samantha J; Weyland, David R; Gray, Sarah K; McGee-Lawrence, Meghan E; Drummer, Thomas D; Donahue, Seth W

2013-08-01

Intracortical bone remodeling is persistent throughout life, leading to age related increases in osteon population density (OPD). Intracortical porosity also increases with age in many mammals including humans, contributing to bone fragility and fracture risk. Unbalanced bone resorption and formation during disuse (e.g., physical inactivity) also increases intracortical porosity. In contrast, hibernating bears are a naturally occurring model for the prevention of both age-related and disuse osteoporoses. Intracortical bone remodeling is decreased during hibernation, but resorption and formation remain balanced. Black bears spend 0.25-7 months in hibernation annually depending on climate and food availability. We found longer hibernating bears demonstrate lower OPD and higher cortical bone mineralization than bears with shorter hibernation durations, but we surprisingly found longer hibernating bears had higher intracortical porosity. However, bears from three different latitudes showed age-related decreases in intracortical porosity, indicating that regardless of hibernation duration, black bears do not show the disuse- or age-related increases in intracortical porosity which is typical of other animals. This ability to prevent increases in intracortical porosity likely contributes to their ability to maintain bone strength during prolonged periods of physical inactivity and throughout life. Improving our understanding of the unique bone metabolism in hibernating bears will potentially increase our ability to develop treatments for age- and disuse-related osteoporoses in humans. Copyright © 2013 Wiley Periodicals, Inc.

Verification of capillary pressure functions and relative permeability equations for gas production

Energy Technology Data Exchange (ETDEWEB)

Jang, Jaewon [Arizona State Univ., Tempe, AZ (United States)

2016-10-25

The understanding of multiphase fluid flow in porous media is of great importance in many fields such as enhanced oil recovery, hydrology, CO₂ sequestration, contaminants cleanup and natural gas production from hydrate bearing sediments. However, there are many unanswered questions about the key parameters that characterize gas and water flows in porous media. The characteristics of multiphase fluid flow in porous media such as water retention curve, relative permeability, preferential fluid flow patterns and fluid-particle interaction should be taken into consideration for a fundamental understanding of the behavior of pore scale systems.

Mechanical Behavior of Low Porosity Carbonate Rock: From Brittle Creep to Ductile Creep.

Science.gov (United States)

Nicolas, A.; Fortin, J.; Gueguen, Y.

2014-12-01

Mechanical compaction and associated porosity reduction play an important role in the diagenesis of porous rocks. They may also affect reservoir rocks during hydrocarbon production, as the pore pressure field is modified. This inelastic compaction can lead to subsidence, cause casing failure, trigger earthquake, or change the fluid transport properties. In addition, inelastic deformation can be time - dependent. In particular, brittle creep phenomena have been deeply investigated since the 90s, especially in sandstones. However knowledge of carbonates behavior is still insufficient. In this study, we focus on the mechanical behavior of a 14.7% porosity white Tavel (France) carbonate rock (>98% calcite). The samples were deformed in a triaxial cell at effective confining pressures ranging from 0 MPa to 85 MPa at room temperature and 70°C. Experiments were carried under dry and water saturated conditions in order to explore the role played by the pore fluids. Two types of experiments have been carried out: (1) a first series in order to investigate the rupture envelopes, and (2) a second series with creep experiments. During the experiments, elastic wave velocities (P and S) were measured to infer crack density evolution. Permeability was also measured during creep experiments. Our results show two different mechanical behaviors: (1) brittle behavior is observed at low confining pressures, whereas (2) ductile behavior is observed at higher confining pressures. During creep experiments, these two behaviors have a different signature in term of elastic wave velocities and permeability changes, due to two different mechanisms: development of micro-cracks at low confining pressures and competition between cracks and microplasticity at high confining pressure. The attached figure is a summary of 20 triaxial experiments performed on Tavel limestone under different conditions. Stress states C',C* and C*' and brittle strength are shown in the P-Q space: (a) 20°C and dry

Porosity model for simultaneous radionuclide transfer in compact clay

International Nuclear Information System (INIS)

Grambow, B.; Ribet, S.; Landesman, C.; Altman, S.

2010-01-01

Document available in extended abstract form only. Both, a mono and a dual porosity model have been developed to describe diffusion in bentonite as function of compaction, which give similar results for the diffusion coefficients. There are little advantages but more computation time for the dual porosity model compared to the mono-porosity model. A significant change in paradigm has been proposed to describe diffusion accessible porosity in bentonite: Only a single micro-porosity value is considered for anions, cations and neutral species. Hydration water in the interlayers is considered as part of the solid phase and is not considered as a constitutive part of overall porosity. Since hydration water takes part of the solid phase, it is now possible to explicitly account for retention of HTO by formulating exchange between HTO and water in the interlayers. In the adaptation of the model to experimental data, a single fit constant, the geometric factor G = 7 was used, common to all ions and neutral species and for densities between 0.2 and 1.8 kg.dm -3 . The only input parameters to describe the effect of dry density on diffusion coefficients are the micro porosity (total porosity minus interlayer porosity) and the hydration numbers of exchanging cations in the interlayers, both of which can be measured by independent means (DRX, water sorption isotherms). The modelling of simultaneous mass transfer of HTO, Cs, Br and Ni has been undertaken. From the results apparent diffusion coefficients were obtained. Effective diffusion coefficients can of course only be compared to literature data if the the same porosity hypothesis is used for Da-De conversion as used in literature (total porosity for anions and HTO, micro-porosity for anions). Then, the calculated apparent diffusion coefficients for HTO match closely the measured values in the mentioned density range. Considering large experimental data uncertainty the agreement between anion diffusion data and calculations

Estimation and measurement of porosity change in cement paste

International Nuclear Information System (INIS)

Lee, Eunyong; Jung, Haeryong; Kwon, Ki-jung; Kim, Do-Gyeum

2011-01-01

Laboratory-scale experiments were performed to understand the porosity change of cement pastes. The cement pastes were prepared using commercially available Type-I ordinary Portland cement (OPC). As the cement pastes were exposed in water, the porosity of the cement pastes sharply increased; however, the slow decrease of porosity was observed as the dissolution period was extended more than 50 days. As expected, the dissolution reaction was significantly influenced by w/c ratio and the ionic strength of solution. A thermodynamic model was applied to simulate the porosity change of the cement pastes. It was highly influenced by the depth of the cement pastes. There was porosity increase on the surface of the cement pastes due to dissolution of hydration products, such as portlandite, ettringite, and CSH. However, the decrease of porosity was estimated inside the cement pastes due to the precipitation of cement minerals. (author)

Analysis of Electrochemical Porosity of Phosphatized Coatings on Galvanized Steel Substrate

Directory of Open Access Journals (Sweden)

Ponte Haroldo de Araújo

2002-01-01

Full Text Available This work refers to the application of a Voltammetric Anodic Dissolution (VAD Technique in the analysis of coating discontinuities, focusing on pores and cracks that exposed the substrate. An evaluation was made of the influence of several parameters, such as the concentration of the passivation solution and sweep rate (SR, on the substrate passivation process and on the porosity indexes of tricationic phosphate coatings of Fe/Zn/Mn. The phosphatization process used was a commercial tricationic Fe/Zn/Mn phosphate bath applied on a galvanized steel (GS substrate. Once the best experimental conditions for the use of the VAD technique had been defined, the grain size and layer weight were related to porosity indexes. The porosity was found to show a tendency to decrease with increasing grain size. The VAD technique consists of the anodic polarization of the substrate/coating system and measurement of the charge density involved in the substrate passivation process. A quantitative porosity index was obtained by comparing the passivation charge density of the substrate without coating (standard passivation charge density and the passivation charge of the coated substrate.

Porosity in fiber laser formation of 5A06 aluminum alloy

Energy Technology Data Exchange (ETDEWEB)

Yu, Yang Chun; Wang, Chun Ming; Hu, Xi Yuan; Wang, Jun; Yu, Sheng Fu [HUST, Wuhan (China)

2010-05-15

The mechanism of porosity formation and its suppression methods in laser formation of aluminum alloy have been studied using a 4kW fiber laser to weld 5A06 aluminum alloy with SAl-Mg5 filler. It was found that the porosity formation is closely related to the stability of the keyhole and fluctuation of the molten pool in the laser welding aluminum alloy. The filling wire increased the instability of the keyhole and weld pool, thus further increasing the amount of gas cavities in the joint. Prefabrication of a suitable gap for the butt joint can provide a natural passage for the flow of the liquid metal, which can weaken, and even completely eliminate the disturbance of the filling wire on the formation of keyhole. The gap can also provide a passage for the escape of the bubble. Thus, this method can greatly decrease the sheet's susceptibility to porosity. Moreover, for a thin sheet, if the power of the laser is sufficient to form a keyhole with stable penetration through the weld sheet, a weld bead without porosity can also be obtained because closing the keyhole is almost impossible

Porosity in fiber laser formation of 5A06 aluminum alloy

International Nuclear Information System (INIS)

Yu, Yang Chun; Wang, Chun Ming; Hu, Xi Yuan; Wang, Jun; Yu, Sheng Fu

2010-01-01

The mechanism of porosity formation and its suppression methods in laser formation of aluminum alloy have been studied using a 4kW fiber laser to weld 5A06 aluminum alloy with SAl-Mg5 filler. It was found that the porosity formation is closely related to the stability of the keyhole and fluctuation of the molten pool in the laser welding aluminum alloy. The filling wire increased the instability of the keyhole and weld pool, thus further increasing the amount of gas cavities in the joint. Prefabrication of a suitable gap for the butt joint can provide a natural passage for the flow of the liquid metal, which can weaken, and even completely eliminate the disturbance of the filling wire on the formation of keyhole. The gap can also provide a passage for the escape of the bubble. Thus, this method can greatly decrease the sheet's susceptibility to porosity. Moreover, for a thin sheet, if the power of the laser is sufficient to form a keyhole with stable penetration through the weld sheet, a weld bead without porosity can also be obtained because closing the keyhole is almost impossible

Multiphase flow modeling of a crude-oil spill site with a bimodal permeability distribution

Science.gov (United States)

Dillard, Leslie A.; Essaid, Hedeff I.; Herkelrath, William N.

1997-01-01

Fluid saturation, particle-size distribution, and porosity measurements were obtained from 269 core samples collected from six boreholes along a 90-m transect at a subregion of a crude-oil spill site, the north pool, near Bemidji, Minnesota. The oil saturation data, collected 11 years after the spill, showed an irregularly shaped oil body that appeared to be affected by sediment spatial variability. The particle-size distribution data were used to estimate the permeability (k) and retention curves for each sample. An additional 344 k estimates were obtained from samples previously collected at the north pool. The 613 k estimates were distributed bimodal lognormally with the two population distributions corresponding to the two predominant lithologies: a coarse glacial outwash deposit and fine-grained interbedded lenses. A two-step geostatistical approach was used to generate a conditioned realization of k representing the bimodal heterogeneity. A cross-sectional multiphase flow model was used to simulate the flow of oil and water in the presence of air along the north pool transect for an 11-year period. The inclusion of a representation of the bimodal aquifer heterogeneity was crucial for reproduction of general features of the observed oil body. If the bimodal heterogeneity was characterized, hysteresis did not have to be incorporated into the model because a hysteretic effect was produced by the sediment spatial variability. By revising the relative permeability functional relation, an improved reproduction of the observed oil saturation distribution was achieved. The inclusion of water table fluctuations in the model did not significantly affect the simulated oil saturation distribution.

An Integrated Capillary, Buoyancy, and Viscous-Driven Model for Brine/CO2Relative Permeability in a Compositional and Parallel Reservoir Simulator

KAUST Repository

Kong, X.; Delshad, M.; Wheeler, M. F.

2012-01-01

The effectiveness of CO2 storage in the saline aquifers is governed by the interplay of capillary, viscous, and buoyancy forces. Recent experimental study reveals the impact of pressure, temperature, and salinity on interfacial tension (IFT) between CO2 and brine. The dependence of CO2-brine relative permeability and capillary pressure on pressure (IFT) is also clearly evident in published experimental results. Improved understanding of the mechanisms that control the migration and trapping of CO2 in subsurface is crucial to design future storage projects that warrant long-term and safe containment. Simulation studies ignoring the buoyancy and also variation in interfacial tension and the effect on the petrophysical properties such as trapped CO2 saturations, relative permeability, and capillary pressure have a poor chance of making accurate predictions of CO2 injectivity and plume migration. We have developed and implemented a general relative permeability model that combines effects of pressure gradient, buoyancy, and IFT in an equation of state (EOS) compositional and parallel simulator. The significance of IFT variations on CO2 migration and trapping is assessed.

An Integrated Capillary, Buoyancy, and Viscous-Driven Model for Brine/CO2Relative Permeability in a Compositional and Parallel Reservoir Simulator

KAUST Repository

Kong, X.

2012-11-03

The effectiveness of CO2 storage in the saline aquifers is governed by the interplay of capillary, viscous, and buoyancy forces. Recent experimental study reveals the impact of pressure, temperature, and salinity on interfacial tension (IFT) between CO2 and brine. The dependence of CO2-brine relative permeability and capillary pressure on pressure (IFT) is also clearly evident in published experimental results. Improved understanding of the mechanisms that control the migration and trapping of CO2 in subsurface is crucial to design future storage projects that warrant long-term and safe containment. Simulation studies ignoring the buoyancy and also variation in interfacial tension and the effect on the petrophysical properties such as trapped CO2 saturations, relative permeability, and capillary pressure have a poor chance of making accurate predictions of CO2 injectivity and plume migration. We have developed and implemented a general relative permeability model that combines effects of pressure gradient, buoyancy, and IFT in an equation of state (EOS) compositional and parallel simulator. The significance of IFT variations on CO2 migration and trapping is assessed.

Porosity effects in flame length of the porous burners

Directory of Open Access Journals (Sweden)

Fatemeh Bahadori

2014-10-01

Full Text Available Furnaces are the devices for providing heat to the industrial systems like boilers, gas turbines and etc. The main challenge of furnaces is emission of huge air pollutants. However, porous burners produce less contaminant compared to others. The quality of the combustion process in the porous burners depends on the length of flame in the porous medium. In this paper, the computational fluid dynamic (CFD is used to investigate the porosity effects on the flame length of the combustion process in porous burner. The simulation results demonstrate that increasing the porosity increases the flame length and the combustion zone extends forward. So, combustion quality increases and production of carbon monoxide decrease. It is possible to conclude that temperature distribution in low porosity burner is lower and more uniform than high porosity one. Therefore, by increasing the porosity of the burner, the production of nitrogen oxides increases. So, using an intermediate porosity in the burner appears to be reasonable.

Altered cement hydration and subsequently modified porosity, permeability and compressive strength of mortar specimens due to the influence of electrical current

NARCIS (Netherlands)

Susanto, A.; Koleva, D.A.; Van Breugel, K.

2014-01-01

This paper reports on the influence of stray current flow on microstructural prop-erties, i.e. pore connectivity and permeability of mortar specimens, and link these to the observed alterations in mechanical properties and cement hydration. Mortar specimens were partly submerged in water and calcium

Porosity measurements of crystalline rocks by laboratory and geophysical methods

International Nuclear Information System (INIS)

Alexander, J.; Hall, D.H.; Storey, B.C.

1981-12-01

Porosity values of igneous and metamorphic crystalline rocks have been determined from core samples taken at specific depths from Altnabreac, by a combination of laboratory and geophysical techniques. Using resaturation and mercury injection methods in three laboratories within I.G.S., porosity values have been derived and the effect of variations in the measuring techniques and results obtained have been compared. Comparison of inter-laboratory porosity values illustrates that systematic errors are present, resulting in higher porosity values for samples subjected to re-testing. This is considered to be caused by the variable nature of the initial samples combined with the inability to completely dry or resaturate samples during a second testing. Geophysical techniques for determining in situ porosity using the neutron log have been carried out in borehole ALA. The neutron log has been calibrated with laboratory derived porosity values and an empirical formula derived enabling porosity values to be ascribed throughout the logged borehole ALA. Comparison of the porosity results from Altnabreac with crystalline samples elsewhere in America, Europe and the U.K. suggest that porosities at Altnabreac are lower than average. However, very few publications concerned with water movement in crystalline areas actually state the method used. (author)

Pulsed neutron porosity logging system

International Nuclear Information System (INIS)

Smith, H.D. Jr.; Smith, M.P.; Schultz, W.E.

1978-01-01

An improved pulsed neutron porosity logging system is provided in the present invention. A logging tool provided with a 14 MeV pulsed neutron source, an epithermal neutron detector, and a fast neutron detector is moved through a borehole. Repetitive bursts of neutrons irradiate the earth formations and, during the bursts, the fast neutron population is sampled. During the interval between bursts the epithermal neutron population is sampled along with background gamma radiation due to lingering thermal neutrons. The fast and epithermal neutron population measurements are combined to provide a measurement of formation porosity

Correlation of Water Frost Porosity in Laminar Flow over Flat Surfaces

Science.gov (United States)

Kandula, Max

2011-01-01

A dimensionless correlation has been proposed for water frost porosity expressing its dependence on frost surface temperature and Reynolds number for laminar forced flow over a flat surface. The correlation is presented in terms of a dimensionless frost surface temperature scaled with the cold plate temperature, and the freezing temperature. The flow Reynolds number is scaled with reference to the critical Reynolds number for laminar-turbulent transition. The proposed correlation agrees satisfactorily with the simultaneous measurements of frost density and frost surface temperature covering a range of plate temperature, ambient air velocity, humidity, and temperature. It is revealed that the frost porosity depends primarily on the frost surface and the plate temperatures and the flow Reynolds number, and is only weakly dependent on the relative humidity. The results also point out the general character of frost porosity displaying a decrease with an increase in flow Reynolds number.

Spark plasma sintering and porosity studies of uranium nitride

Energy Technology Data Exchange (ETDEWEB)

Johnson, Kyle D., E-mail: kylej@kth.se; Wallenius, Janne; Jolkkonen, Mikael; Claisse, Antoine

2016-05-15

In this study, a number of samples of UN sintered by the SPS method have been fabricated, and highly pure samples ranging in density from 68% to 99.8%TD – corresponding to an absolute density of 14.25 g/cm{sup 3} out of a theoretical density of 14.28 g/cm{sup 3} – have been fabricated. By careful adjustment of the sintering parameters of temperature and applied pressure, the production of pellets of specific porosity may now be achieved between these ranges. The pore closure behaviour of the material has also been documented and compared to previous studies of similar materials, which demonstrates that full pore closure using these methods occurs near 97.5% of relative density. - Highlights: • UN pellets are fabricated over a wide array of densities using the SPS method. • The sintereing parameters necessary to produce pellets over a wide array of density space are charted. • Pellets of extremely high density (99.9% of TD, absolute density of 14.25 g/cm{sup 3}) are fabricated. • Full-closure of the porosity in this material is obtained at around 2.5% of total porosity.

Fabrication of dual porosity electrode structure

Science.gov (United States)

Smith, J.L.; Kucera, E.H.

1991-02-12

A substantially entirely fibrous ceramic is described which may have dual porosity of both micro and macro pores. Total porosity may be 60-75% by volume. A method of spraying a slurry perpendicularly to an ambient stream of air is disclosed along with a method of removing binders without altering the fiber morphology. Adding fine ceramic particulates to the green ceramic fibers enhances the sintering characteristics of the fibers. 3 figures.

Generating porosity spectrum of carbonate reservoirs using ultrasonic imaging log

Science.gov (United States)

Zhang, Jie; Nie, Xin; Xiao, Suyun; Zhang, Chong; Zhang, Chaomo; Zhang, Zhansong

2018-03-01

Imaging logging tools can provide us the borehole wall image. The micro-resistivity imaging logging has been used to obtain borehole porosity spectrum. However, the resistivity imaging logging cannot cover the whole borehole wall. In this paper, we propose a method to calculate the porosity spectrum using ultrasonic imaging logging data. Based on the amplitude attenuation equation, we analyze the factors affecting the propagation of wave in drilling fluid and formation and based on the bulk-volume rock model, Wyllie equation and Raymer equation, we establish various conversion models between the reflection coefficient β and porosity ϕ. Then we use the ultrasonic imaging logging and conventional wireline logging data to calculate the near-borehole formation porosity distribution spectrum. The porosity spectrum result obtained from ultrasonic imaging data is compared with the one from the micro-resistivity imaging data, and they turn out to be similar, but with discrepancy, which is caused by the borehole coverage and data input difference. We separate the porosity types by performing threshold value segmentation and generate porosity-depth distribution curves by counting with equal depth spacing on the porosity image. The practice result is good and reveals the efficiency of our method.

Casting Porosity-Free Grain Refined Magnesium Alloys

Energy Technology Data Exchange (ETDEWEB)

Schwam, David [Case Western Reserve University

2013-08-12

The objective of this project was to identify the root causes for micro-porosity in magnesium alloy castings and recommend remedies that can be implemented in production. The findings confirm the key role played by utilizing optimal gating and risering practices in minimizing porosity in magnesium castings. 

Investigation on the Permeability Evolution of Gypsum Interlayer Under High Temperature and Triaxial Pressure

Science.gov (United States)

Tao, Meng; Yechao, You; Jie, Chen; Yaoqing, Hu

2017-08-01

reduced, which eventually leads to a decrease in permeability. When the inlet gas pressure is between 2 and 6 MPa, the Klinkenberg effect dribbles away, and the gas flow gradually obeys to the Darcy's law. Hence, the permeability increased with the increase in inlet gas pressure. (c) The curve of permeability versus temperature is divided into five stages based on its gradient. In the temperature range of 20-100 °C, the permeability of gypsum decreased slowly when the temperature decreased. From 100 to 200 °C, the permeability of gypsum increased dramatically when the temperature increased. However, a dramatic increase in permeability was observed from 200 to 450 °C. Subsequently, in the temperature range of 450-550 °C, due to closure of pores and fractures, the permeability of the specimens slowly lessened when the temperature increased. From 550 to 650 °C, the permeability of gypsum slightly increased when the temperature increased; (d) the micro-cracks and porosity obtained from the CT images show a high degree of consistency to the permeability evolution; (e) when compared to the permeability evolutions of sandstone, granite, and lignite, gypsum exhibits a stable evolution trend of permeability and has a much greater threshold temperature when its permeability increases sharply. The results of the paper may provide essential and valuable references for the design and construction of high-level radioactive wastes repository in bedded salt rock containing gypsum interlayers.

Porosity evolution in Icelandic hydrothermal systems

Science.gov (United States)

Thien, B.; Kosakowski, G.; Kulik, D. A.

2014-12-01

Mineralogical alteration of reservoir rocks, driven by fluid circulation in natural or enhanced hydrothermal systems, is likely to influence the long-term performance of geothermal power generation. A key factor is the change of porosity due to dissolution of primary minerals and precipitation of secondary phases. Porosity changes will affect fluid circulation and solute transport, which, in turn, influence mineralogical alteration. This study is part of the Sinergia COTHERM project (COmbined hydrological, geochemical and geophysical modeling of geotTHERMal systems, grant number CRSII2_141843/1) that is an integrative research project aimed at improving our understanding of the sub-surface processes in magmatically-driven natural geothermal systems. These are typically high enthalphy systems where a magmatic pluton is located at a few kilometers depth. These shallow plutons increase the geothermal gradient and trigger the circulation of hydrothermal waters with a steam cap forming at shallow depth. Field observations suggest that active and fossil Icelandic hydrothermal systems are built from a superposition of completely altered and completely unaltered layers. With help of 1D and 2D reactive transport models (OpenGeoSys-GEM code), we investigate the reasons for this finding, by studying the mineralogical evolution of protoliths with different initial porosities at different temperatures and pressures, different leaching water composition and gas content, and different porosity geometries (i.e. porous medium versus fractured medium). From this study, we believe that the initial porosity of protoliths and volume changes due to their transformation into secondary minerals are key factors to explain the different alteration extents observed in field studies. We also discuss how precipitation and dissolution kinetics can influence the alteration time scales.

Application of X-ray CT investigation of CO{sub 2}-brine flow in porous media

Energy Technology Data Exchange (ETDEWEB)

Jiang, Lanlan; Liu, Yu; Song, Yongchen; Yang, Mingjun; Zhao, Yuechao; Zhao, Jiafei; Zhang, Yi; Shen, Zijian [Dalian University of Technology, Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian (China); Xue, Ziqiu [Research Institute of Innovative Technology for the Earth, Kizugawa City, Kyoto (Japan); Suekane, Tetsuya [Tokyo Institute Technology, Department of Energy Sciences, Nagatsuta, Yokohama (Japan)

2015-05-15

A clear understanding of two-phase flows in porous media is important for investigating CO{sub 2} geological storage. In this study, we conducted an experiment of CO{sub 2}/brine flow process in porous media under sequestration conditions using X-ray CT technique. The flow properties of relative permeability, porosity heterogeneity, and CO{sub 2} saturation were observed in this experiment. The porous media was packed with glass beads having a diameter of 0.2 mm. The porosity distribution along the flow direction is heterogeneous owing to the diameter and shape of glass beads along the flow direction. There is a relationship between CO{sub 2} saturation and porosity distribution, which changes with different flow rates and fractional flows. The heterogeneity of the porous media influences the distribution of CO{sub 2}; moreover, gravity, fractional flows, and flow rates influence CO{sub 2} distribution and saturation. The relative permeability curve was constructed using the steady-state method. The results agreed well with the relative permeability curve simulated using pore-network model. (orig.)

Effect of shrinkage porosity on mechanical properties of ferritic ductile iron

Directory of Open Access Journals (Sweden)

Wang Zehua

2013-05-01

Full Text Available Casting defects could largely affect the mechanical properties of casting products. A number of test pieces made of ductile iron (EN-GJS-400-18-LT with different levels of shrinkage porosity were prepared and then tensile and fatigue tests were performed to investigate the impact of shrinkage porosity on their mechanical properties. The results showed that the tensile strength decreases linearly with increasing of the shrinkage porosity. The tensile elongation decreases sharply with the increase of the shrinkage porosity mainly due to the non-uniform plastic deformation. The fatigue life also dramatically declines with increasing of the porosity and follows a power law relationship with the area percentage of porosity. The existence of the shrinkage porosity made the fatigue fracture complex. The shrinkage pores, especially those close to the surface usually became the crack initiation sites. For test pieces with less porosity, the fatigue fracture was clearly composed of crack initiation, propagation, and overloading. While for samples with high level of porosity, multiple crack initiation sites were observed.

The Production of Porous Hydroxyapatite Scaffolds with Graded Porosity by Sequential Freeze-Casting.

Science.gov (United States)

Lee, Hyun; Jang, Tae-Sik; Song, Juha; Kim, Hyoun-Ee; Jung, Hyun-Do

2017-03-31

Porous hydroxyapatite (HA) scaffolds with porosity-graded structures were fabricated by sequential freeze-casting. The pore structures, compressive strengths, and biocompatibilities of the fabricated porous HA scaffolds were evaluated. The porosities of the inner and outer layers of the graded HA scaffolds were controlled by adjusting the initial HA contents of the casting slurries. The interface between the dense and porous parts was compact and tightly adherent. The porosity and compressive strengths of the scaffold were controlled by the relative thicknesses of the dense/porous parts. In addition, the porous HA scaffolds showed good biocompatibility in terms of preosteoblast cell attachment and proliferation. The results suggest that porous HA scaffolds with load-bearing parts have potential as bone grafts in hard-tissue engineering.

Formation of peripheral porosity regions around urania in zirconia-urania mixed oxide powder compact sintering

International Nuclear Information System (INIS)

Das, P.; Choudhury, R.

1992-01-01

Sintering studies of zirconia-urania mixed oxide powder compacts (in stages of 5% urania up to a maximum of 20% addition) were carried out at temperatures between 1000-1400deg C for various soaking periods. The formation of a peripheral porosity region around comparatively coarser urania particle was a characteristic feature in this mixed oxide sintered compact. At even a higher sintering temperature (1800deg C), where extensive solid solution formation takes place, this porosity region demarcates the solutionized particles from the host zirconia apparently acting as a discontinuity in the system. Relative shrinkage difference between the dissimilar particles probably contributes to the porosity regions around the minor second phase at a lower temperature while at higher temperature generation of 'Kirkendall porosity' may be responsible for such an effect. (orig.)

Stylolites, porosity, depositional texture, and silicates in chalk facies sediments

DEFF Research Database (Denmark)

Fabricius, Ida Lykke; Borre, Mai K.

2007-01-01

dissolution around 490 m below sea floor (bsf) corresponds to an interval of waning porosity-decline, and even the occurrence of proper stylolites from 830 m bsf is accompanied by only minor porosity reduction. Because opal is present, the pore-water is relatively rich in Si which through the formation of Ca......-silica complexes causes an apparent super-saturation of Ca and retards cementation. The onset of massive pore-filling cementation at 1100 m bsf may be controlled by the temperature-dependent transition from opal-CT to quartz. In the stylolite-bearing chalk of two wells in the Gorm and Tyra fields, the nannofossil...... matrix shows recrystallization but only minor pore-filling cement, whereas microfossils are cemented. Cementation in Gorm and Tyra is thus partial and has apparently not been retarded by opal-controlled pore-water. A possible explanation is that, due to the relatively high temperature, silica has...

Physical Explanation of Archie's Porosity Exponent in Granular Materials: A Process-Based, Pore-Scale Numerical Study

Science.gov (United States)

Niu, Qifei; Zhang, Chi

2018-02-01

The empirical Archie's law has been widely used in geosciences and engineering to explain the measured electrical resistivity of many geological materials, but its physical basis has not been fully understood yet. In this study, we use a pore-scale numerical approach combining discrete element-finite difference methods to study Archie's porosity exponent m of granular materials over a wide porosity range. Numerical results reveal that at dilute states (e.g., porosity ϕ > 65%), m is exclusively related to the particle shape and orientation. As the porosity decreases, the electric flow in pore space concentrates progressively near particle contacts and m increases continuously in response to the intensified nonuniformity of the local electrical field. It is also found that the increase in m is universally correlated with the volume fraction of pore throats for all the samples regardless of their particle shapes, particle size range, and porosities.

Porosity and liquid absorption of cement paste

DEFF Research Database (Denmark)

Krus, M.; Hansen, Kurt Kielsgaard; Kunzel, H. M.

1997-01-01

be a slowing-down effect which is related to water because the absorption of organic liquids, such as hexane, is quite normal. Measurements of the porosity of hardened cement paste determined by helium pycnometry and water saturation show that water molecules can enter spaces in the microstructure which...... are not accessible to the smaller helium atoms. Considering the results of dilatation tests both before and after water and hexane saturation, it seems possible that a contraction of capillary pores due to moisture-related swelling of the cement gel leads to the non-linear water absorption over the square root...

Impact of porosity variation on diffusive transport: experimentation vs simulation

International Nuclear Information System (INIS)

Fatnassi, Ikram

2015-01-01

Reactions induced by the diffusion of reactants from different sources may alter rock confinement properties, and are therefore critical processes to assess short-term and long-term behaviour of rocks displaying a low permeability, such as argillites which are used as barriers in underground storage installation. In order to test transport-chemistry codes based on a continuous approach, the author of this research thesis reports the development and performance of simplest as possible experiments of sealing/dissolution diffusion, by using porous media of increasing complexity: compact sand, sintered glass, stoneware, chalk, until a material close to that envisaged within the frame of a storage like a Tournemire argillite. The principle of these experiments relies on the characterisation of the diffusive behaviour of an inert tracer within a porous medium submitted to dissolution reactions (attack of a carbonate matrix by an acid solution) and/or precipitation of mineral compounds (calcium oxalate, gypsum or barite) which results in an evolution of porosity and a modification of the diffusive transport of the studied tracer. At the end of the experiment, porous media and precipitates are characterised by SEM-EDS [fr

Electrospun polyacrylonitrile nanofibrous membranes with varied fiber diameters and different membrane porosities as lithium-ion battery separators

International Nuclear Information System (INIS)

Ma, Xiaojing; Kolla, Praveen; Yang, Ruidong; Wang, Zhao; Zhao, Yong; Smirnova, Alevtina L.; Fong, Hao

2017-01-01

Highlights: • Nine types of electrospun polyacrylonitrile nanofibrous membranes were prepared. • These membranes had varied fiber diameters and different membrane porosities. • The membranes were explored as innovative Li-ion battery (LIB) separators. • The hot-pressed membrane with thin fibers had superior performance as LIB separator. - Abstract: In this study, nine types of polyacrylonitrile (PAN) nanofibrous membranes with varied fiber diameters and different membrane porosities are prepared by electrospinning followed by hot-pressing. Subsequently, these membranes are explored as Li-ion battery (LIB) separators. The impacts of fiber diameter and membrane porosity on electrolyte uptake, Li"+ ion transport through the membrane, electrochemical oxidation potential, and membrane performance as LIB separator (during charge/discharge cycling and rate capability tests of a cathodic half-cell) have been investigated. When compared to commercial Celgard PP separator, hot-pressed electrospun PAN nanofibrous membranes exhibit larger electrolyte uptake, higher thermal stability, wider electrochemical potential window, higher Li"+ ion permeability, and better electrochemical performance in LiMn_2O_4/separator/Li half-cell. The results also indicate that the PAN-based membrane/separator with small fiber diameters of 200–300 nm and hot-pressed under high pressure of 20 MPa surpasses all other membranes/separators and demonstrates the best performance, leading to the highest discharge capacity (89.5 mA h g"−"1 at C/2 rate) and cycle life (with capacity retention ratio being 97.7%) of the half-cell. In summary, this study has revealed that the hot-pressed electrospun PAN nanofibrous membranes (particularly those consisting of thin nanofibers) are promising as high-performance LIB separators.

Grain-Size Dynamics Beneath Mid-Ocean Ridges: Implications for Permeability and Melt Extraction

Science.gov (United States)

Turner, A. J.; Katz, R. F.; Behn, M. D.

2014-12-01

The permeability structure of the sub-ridge mantle plays an important role in how melt is focused and extracted at mid-ocean ridges. Permeability is controlled by porosity and the grain size of the solid mantle matrix, which is in turn controlled by the deformation conditions. To date, models of grain size evolution and mantle deformation have not been coupled to determine the influence of spatial variations in grain-size on the permeability structure at mid-ocean ridges. Rather, current models typically assume a constant grain size for the whole domain [1]. Here, we use 2-D numerical models to evaluate the influence of grain-size variability on the permeability structure beneath a mid-ocean ridge and use these results to speculate on the consequences for melt focusing and extraction. We construct a two-dimensional, single phase model for the steady-state grain size beneath a mid-ocean ridge. The model employs a composite rheology of diffusion creep, dislocation creep, dislocation accommodated grain boundary sliding, and a brittle stress limiter. Grain size is calculated using the "wattmeter" model of Austin and Evans [2]. We investigate the sensitivity of the model to global variations in grain growth exponent, potential temperature, spreading-rate, and grain boundary sliding parameters [3,4]. Our model predicts that permeability varies by two orders of magnitude due to the spatial variability of grain size within the expected melt region of a mid-ocean ridge. The predicted permeability structure suggests grain size may promote focusing of melt towards the ridge axis. Furthermore, the calculated grain size structure should focus melt from a greater depth than models that exclude grain-size variability. Future work will involve evaluating this hypothesis by implementing grain-size dynamics within a two-phase mid-ocean ridge model. The developments of such a model will be discussed. References: [1] R. F. Katz, Journal of Petrology, volume 49, issue 12, page 2099

Relationship between micro-porosity and tensile properties of 6063 alloy

Directory of Open Access Journals (Sweden)

Li Xiehua

2013-01-01

Full Text Available The micro-porosity is usually present in the as-cast microstructure, which decreases the tensile strength and ductility and therefore limit the application of cast aluminum parts. Although much work has been done to investigate the effects of various casting parameters on the formation of porosity in various aluminum alloys, up to now, little information has been available for the relationship between micro-porosity and tensile properties of 6063 alloy. In this study, the influences of size and area fraction of micro-porosity on the tensile properties and fracture behavior of 6063 aluminum alloy were investigated by means of tensile testing, optical microscopy (OM, and scanning electron microscopy (SEM. The tensile tests were conducted in air at 100 ℃, 200 ℃ and 300 ℃, respectively. Results show that the large micro-porosity with sizes between 100 μm and 800 μm located at the center and top of the ingot, while the small micro-porosity with size between 2 μm and 60 μm distributed at the edge and bottom of the ingot. The area fraction of micro-porosity at the center of the ingot is much bigger than that at the edge of the ingot. When tested at 100 ℃, with the decrease in the area fraction of micro-porosity from the top of the ingot to the bottom of the ingot, the ultimate tensile strength, yield strength and the elongation are increased from 82 to 99 MPa, 32 to 66 MPa and 7% to 11%, respectively. When the temperature is no more than 200 ℃, the strain hardening exponent decreases with an increase in the area fraction of micro-porosity; while the deviation disappears when the temperature reaches 300 ℃. The fracture mode of the alloy is greatly influenced by the size and area fraction of the micro-porosity.

Estimation of hydraulic permeability considering the micro morphology of rocks of the borehole YAXCOPOIL-1 (Impact crater Chicxulub, Mexico)

Science.gov (United States)

Mayr, S. I.; Burkhardt, H.; Popov, Yu.; Wittmann, A.

2008-04-01

Internal surface, formation factor, Nuclear Magnetic Resonance (NMR)-T2 relaxation times and pore radius distributions were measured on representative core samples for the estimation of hydraulic permeability. Permeability is estimated using various versions of the classic Kozeny-Carman-equation (K-C) and a further development of K-C, the fractal PaRiS-model, taking into account the internal surface. In addition to grain and pore size distribution, directly connected to permeability, internal surface reflects the internal structure (“micro morphology”). Lithologies could be grouped with respect to differences in internal surface. Most melt rich impact breccia lithologies exhibit large internal surfaces, while Tertiary post-impact sediments and Cretaceous lithologies in displaced megablocks display smaller internal surfaces. Investigations with scanning electron microscopy confirm the correlation between internal surface and micro morphology. In addition to different versions of K-C, estimations by means of NMR, pore radius distributions and some gas permeability measurements serve for cross-checking and calibration. In general, the different estimations from the independent methods and the measurements are in satisfactory accordance. For Tertiary limestones and Suevites bulk with very high porosities (up to 35%) permeabilites between 10-14 and 10-16 m2 are found, whereas in lower Suevite, Cretaceous anhydrites and dolomites, bulk permeabilites are between 10-15 and 10-23 m2.

Carbonate reservoir characterization with lithofacies clustering and porosity prediction

International Nuclear Information System (INIS)

Al Moqbel, Abdulrahman; Wang, Yanghua

2011-01-01

One of the objectives in reservoir characterization is to quantitatively or semi-quantitatively map the spatial distribution of its heterogeneity and related properties. With the availability of 3D seismic data, artificial neural networks are capable of discovering the nonlinear relationship between seismic attributes and reservoir parameters. For a target carbonate reservoir, we adopt a two-stage approach to conduct characterization. First, we use an unsupervised neural network, the self-organizing map method, to classify the reservoir lithofacies. Then we apply a supervised neural network, the back-propagation algorithm, to quantitatively predict the porosity of the carbonate reservoir. Based on porosity maps at different time levels, we interpret the target reservoir vertically related to three depositional phases corresponding to, respectively, a lowstand system tract before sea water immersion, a highstand system tract when water covers organic deposits and a transition zone for the sea level falling. The highstand system is the most prospective zone, given the organic content deposited during this stage. The transition zone is also another prospective feature in the carbonate depositional system due to local build-ups

Effect of keyhole characteristics on porosity formation during pulsed laser-GTA hybrid welding of AZ31B magnesium alloy

Science.gov (United States)

Chen, Minghua; Xu, Jiannan; Xin, Lijun; Zhao, Zuofu; Wu, Fufa; Ma, Shengnan; Zhang, Yue

2017-06-01

This paper experimentally investigates the relationship between laser keyhole characteristics on the porosity formation during pulsed laser-GTA welding of magnesium alloy. Based on direct observations during welding process, the influences of laser keyhole state on the porosity formation were studied. Results show that the porosities in the joint are always at the bottom of fusion zone of the joint, which is closely related to the keyhole behavior. A large depth to wide ratio always leads to the increase of porosity generation chance. Keeping the keyhole outlet open for a longer time benefits the porosity restriction. Overlap of adjacent laser keyhole can effectively decrease the porosity generation, due to the cutting effect between adjacent laser keyholes. There are threshold overlap rate values for laser keyholes in different state.

Oil recovery enhancement from fractured, low permeability reservoirs. Annual report 1990--1991, Part 1

Energy Technology Data Exchange (ETDEWEB)

Poston, S.W.

1991-12-31

Joint funding by the Department of Energy and the State of Texas has Permitted a three year, multi-disciplinary investigation to enhance oil recovery from a dual porosity, fractured, low matrix permeability oil reservoir to be initiated. The Austin Chalk producing horizon trending thru the median of Texas has been identified as the candidate for analysis. Ultimate primary recovery of oil from the Austin Chalk is very low because of two major technological problems. The commercial oil producing rate is based on the wellbore encountering a significant number of natural fractures. The prediction of the location and frequency of natural fractures at any particular region in the subsurface is problematical at this time, unless extensive and expensive seismic work is conducted. A major portion of the oil remains in the low permeability matrix blocks after depletion because there are no methods currently available to the industry to mobilize this bypassed oil. The following multi-faceted study is aimed to develop new methods to increase oil and gas recovery from the Austin Chalk producing trend. These methods may involve new geological and geophysical interpretation methods, improved ways to study production decline curves or the application of a new enhanced oil recovery technique. The efforts for the second year may be summarized as one of coalescing the initial concepts developed during the initial phase to more in depth analyses. Accomplishments are predicting natural fractures; relating recovery to well-log signatures; development of the EOR imbibition process; mathematical modeling; and field test.

Mechanical and hydraulic behaviour of compacting crushed salt backfill at low porosities. Project REPOPERM. Phase 2

Energy Technology Data Exchange (ETDEWEB)

Kroehn, Klaus-Peter; Czaikowski, Oliver; Wieczorek, Klaus; Zhang, Chun-Liang; Moog, Helge; Friedenberg, Larissa [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) gGmbH, Koeln (Germany); Stuehrenberg, Dieter; Heemann, Ulrich [Bundesanstalt fuer Geowissenschaften und Rohstoffe (BGR), Hannover (Germany); Jobmann, Michael; Mueller, Christian; Schirmer, Sonja [DBE Technology GmbH (DBE TEC), Peine (Germany)

2017-02-15

The compaction behavior of crushed salt has been extensively investigated by means of experimental as well as theoretical work. The readiness of numerical tools for the application to modeling the complex coupled thermo-hydro-mechanical processes in the crushed salt backfilled in a repository in salt rock has also been demonstrated. Compaction tests were performed under repository-relevant conditions. These tests were supplemented by laboratory work aiming at specific aspects of compaction. The following list covers the topics of these investigations as well as the main results. - Revisiting the determination of the porosity in relevant, past experiments (BGR). - Influence of the grain size distribution on compaction (BGR). - Triaxial compaction test with dry material at low porosities (BGR). - Investigation of the influence of humidity on compaction covers several subtopics. - Permeability associated with low porosity includes two subtopics. - Constitutive equations for two -phase flow (GRS). - Microstructural Investigations (DBE TEC). Parallel to the experimental work attention focussed on several aspects of the basics for modelling the compaction of crushed salt. This work covers checking the validity of the established numerical tools as well as exploring new methods. Topics and main results are listed here: - Development/definition and comparison of constitutive models (BGR). - Benchmark calculations (BGR and GRS). - Capability of scaling-rules for capillary pressure from the oil industry (GRS). - Application of discrete element codes to compacting crushed salt (DBE TEC). Finally, repository-relevant scenarios are discussed as a basis for a realistic but generic numerical model of brine inflow in to a converging back filled drift under a thermal gradient (GRS). This exercise demonstrates the feasibility of modelling crushed salt compaction as a fully coupled thermohydraulic-mechanical process including two-phase flow effects.

Mechanical and hydraulic behaviour of compacting crushed salt backfill at low porosities. Project REPOPERM. Phase 2

International Nuclear Information System (INIS)

Kroehn, Klaus-Peter; Czaikowski, Oliver; Wieczorek, Klaus; Zhang, Chun-Liang; Moog, Helge; Friedenberg, Larissa; Stuehrenberg, Dieter; Heemann, Ulrich; Jobmann, Michael; Mueller, Christian; Schirmer, Sonja

2017-02-01

The compaction behavior of crushed salt has been extensively investigated by means of experimental as well as theoretical work. The readiness of numerical tools for the application to modeling the complex coupled thermo-hydro-mechanical processes in the crushed salt backfilled in a repository in salt rock has also been demonstrated. Compaction tests were performed under repository-relevant conditions. These tests were supplemented by laboratory work aiming at specific aspects of compaction. The following list covers the topics of these investigations as well as the main results. - Revisiting the determination of the porosity in relevant, past experiments (BGR). - Influence of the grain size distribution on compaction (BGR). - Triaxial compaction test with dry material at low porosities (BGR). - Investigation of the influence of humidity on compaction covers several subtopics. - Permeability associated with low porosity includes two subtopics. - Constitutive equations for two -phase flow (GRS). - Microstructural Investigations (DBE TEC). Parallel to the experimental work attention focussed on several aspects of the basics for modelling the compaction of crushed salt. This work covers checking the validity of the established numerical tools as well as exploring new methods. Topics and main results are listed here: - Development/definition and comparison of constitutive models (BGR). - Benchmark calculations (BGR and GRS). - Capability of scaling-rules for capillary pressure from the oil industry (GRS). - Application of discrete element codes to compacting crushed salt (DBE TEC). Finally, repository-relevant scenarios are discussed as a basis for a realistic but generic numerical model of brine inflow in to a converging back filled drift under a thermal gradient (GRS). This exercise demonstrates the feasibility of modelling crushed salt compaction as a fully coupled thermohydraulic-mechanical process including two-phase flow effects.

Modeling stress/strain-dependent permeability changes for deep geoenergy applications

Science.gov (United States)

Rinaldi, Antonio Pio; Rutqvist, Jonny

2016-04-01

Rock permeability is a key parameter in deep geoenergy systems. Stress and strain changes induced at depth by fluid injection or extraction may substantially alter the rock permeability in an irreversible way. With regard to the geoenergies, some applications require the permeability to be enhanced to improve productivity. The rock permeability is generally enhanced by shearing process of faults and fractures (e.g. hydroshearing for Enhanced and Deep Geothermal Systems), or the creation of new fractures (e.g. hydrofracturing for shale gas). However, such processes may, at the same time, produce seismicity that can be felt by the local population. Moreover, the increased permeability due to fault reactivation may pose at risk the sealing capacity of a storage site (e.g. carbon sequestration or nuclear waste disposal), providing then a preferential pathway for the stored fluids to escape at shallow depth. In this work we present a review of some recent applications aimed at understanding the coupling between stress (or strain) and permeability. Examples of geoenergy applications include both EGS and CO2 sequestration. To investigate both "wanted" and "unwanted" effects, THM simulations have been carried out with the TOUGH-FLAC simulator. Our studies include constitutive equations relating the permeability to mean effective stress, effective normal stress, volumetric strain, as well as accounting for permeability variation as related to fault/fracture reactivation. Results show that the geomechanical effects have a large role in changing the permeability, hence affecting fluids leakage, reservoir enhancement, as well as the induced seismicity.

Active intestinal drug absorption and the solubility-permeability interplay.

Science.gov (United States)

Porat, Daniel; Dahan, Arik

2018-02-15

The solubility-permeability interplay deals with the question: what is the concomitant effect on the drug's apparent permeability when increasing the apparent solubility with a solubility-enabling formulation? The solubility and the permeability are closely related, exhibit certain interplay between them, and ongoing research throughout the past decade shows that treating the one irrespectively of the other may be insufficient. The aim of this article is to provide an overview of the current knowledge on the solubility-permeability interplay when using solubility-enabling formulations for oral lipophilic drugs, highlighting active permeability aspects. A solubility-enabling formulation may affect the permeability in opposite directions; the passive permeability may decrease as a result of the apparent solubility increase, according to the solubility-permeability tradeoff, but at the same time, certain components of the formulation may inhibit/saturate efflux transporters (when relevant), resulting in significant apparent permeability increase. In these cases, excipients with both solubilizing and e.g. P-gp inhibitory properties may lead to concomitant increase of both the solubility and the permeability. Intelligent development of such formulation will account for the simultaneous effects of the excipients' nature/concentrations on the two arms composing the overall permeability: the passive and the active arms. Overall, thorough mechanistic understanding of the various factors involved in the solubility-permeability interplay may allow developing better solubility-enabling formulations, thereby exploiting the advantages analyzed in this article, offering oral delivery solution even for BCS class IV drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

Porosity Measurements and Analysis for Metal Additive Manufacturing Process Control.

Science.gov (United States)

Slotwinski, John A; Garboczi, Edward J; Hebenstreit, Keith M

2014-01-01

Additive manufacturing techniques can produce complex, high-value metal parts, with potential applications as critical metal components such as those found in aerospace engines and as customized biomedical implants. Material porosity in these parts is undesirable for aerospace parts - since porosity could lead to premature failure - and desirable for some biomedical implants - since surface-breaking pores allows for better integration with biological tissue. Changes in a part's porosity during an additive manufacturing build may also be an indication of an undesired change in the build process. Here, we present efforts to develop an ultrasonic sensor for monitoring changes in the porosity in metal parts during fabrication on a metal powder bed fusion system. The development of well-characterized reference samples, measurements of the porosity of these samples with multiple techniques, and correlation of ultrasonic measurements with the degree of porosity are presented. A proposed sensor design, measurement strategy, and future experimental plans on a metal powder bed fusion system are also presented.

Mathematical aspects of multi-porosity continua

CERN Document Server

Straughan, Brian

2017-01-01

This book is devoted to describing theories for porous media where such pores have an inbuilt macro structure and a micro structure. For example, a double porosity material has pores on a macro scale, but additionally there are cracks or fissures in the solid skeleton. The actual body is allowed to deform and thus the underlying theory is one of elasticity. Various different descriptions are reviewed. Chapter 1 introduces the classical linear theory of elastodynamics together with uniqueness and continuous dependence results. Chapters 2 and 3 review developments of theories for double and triple porosity using a pressure-displacement structure and also using voids-displacement. Chapter 4 compares various aspects of the pressure-displacement and voids-displacement theories via uniqueness studies and wave motion analysis. Mathematical analyses of double and triple porosity materials are included concentrating on uniqueness and stability studies in chapters 5 to 7. In chapters 8 and 9 the emphasis is on wa...

New quantitative methods for mineral and porosity mapping in clayey materials: application to the compacted bentonites of engineered barriers

International Nuclear Information System (INIS)

Pret, D.

2003-12-01

Clayey materials are well known for their non permeable properties and their textural changes between the dry and hydrated states. Their porous network is classically investigated in the dry state using bulk measurements. However, the relationship between porosity and mineral spatial heterogeneities in the hydrated state is poorly understood. The textural analysis limits induce some difficulties to understand the migration of solute species into compacted bentonites (as for nuclear waste repository). The goal of this work is to improve the analysis techniques for hydrated clayey materials in order to provide a multi-scale quantitative petrography. The bentonite samples are impregnated using a resin whose properties are close to water ones. The classical petrographic study reveals strong heterogeneities of spatial and size distributions of porosity and minerals. SEM images analysis allows a quantification and a simple mapping of pores and minerals into unaltered bentonites. Nevertheless, as alterations are suspected to happen in the repository context, two methods for the analysis of all types of materials have been also developed. Two specific softwares permits the treatments of autoradiographs and chemical element maps obtained using electron microprobe. The results are quantitative maps highlighting the spatial porosity heterogeneities from the decimetric to the micrometric scales. All pore sizes are taken into account including clay interlayer spaces. Moreover, an accurate mineral mapping is also supplied on millimetric areas with a spatial resolution close to the micrometer. In a widely point of view, this work provides new complementary tools for the textural analysis of fine grained materials and the improvement of migration modelling of solute species. (author)

Ageing-induced enhancement of open porosity of mesoporous silica films studied by positron annihilation spectroscopy

International Nuclear Information System (INIS)

He Chunqing; Muramatsu, Makoto; Oshima, Nagayasu; Ohdaira, Toshiyuki; Kinomura, Atsushi; Suzuki, Ryoichi

2006-01-01

We show that ageing of the silica sol in a closed vessel enhanced the open porosity of calcined mesoporous silica film studied by positron. Positron annihilation lifetime spectroscopy (PALS) based on a pulsed slow positron beam was used to estimate the mesopore size. 2-dimensional PALS (2D-PALS) and ortho-positronium time-of-flight (Ps-TOF) were used to evaluate the open porosity, interconnectivity and tortuosity of mesopores in the silica films. Results revealed that little change in pore size but significant enhancement of open porosity and/or pore interconnectivity occurred in the silica film deposited after the precursor solution aged for a relative longer time

Low resistivity and permeability in actively deforming shear zones on the San Andreas Fault at SAFOD

Science.gov (United States)

Morrow, Carolyn A.; Lockner, David A.; Hickman, Stephen H.

2015-01-01

The San Andreas Fault Observatory at Depth (SAFOD) scientific drillhole near Parkfield, California crosses the San Andreas Fault at a depth of 2.7 km. Downhole measurements and analysis of core retrieved from Phase 3 drilling reveal two narrow, actively deforming zones of smectite-clay gouge within a roughly 200 m-wide fault damage zone of sandstones, siltstones and mudstones. Here we report electrical resistivity and permeability measurements on core samples from all of these structural units at effective confining pressures up to 120 MPa. Electrical resistivity (~10 ohm-m) and permeability (10-21 to 10-22 m2) in the actively deforming zones were one to two orders of magnitude lower than the surrounding damage zone material, consistent with broader-scale observations from the downhole resistivity and seismic velocity logs. The higher porosity of the clay gouge, 2 to 8 times greater than that in the damage zone rocks, along with surface conduction were the principal factors contributing to the observed low resistivities. The high percentage of fine-grained clay in the deforming zones also greatly reduced permeability to values low enough to create a barrier to fluid flow across the fault. Together, resistivity and permeability data can be used to assess the hydrogeologic characteristics of the fault, key to understanding fault structure and strength. The low resistivities and strength measurements of the SAFOD core are consistent with observations of low resistivity clays that are often found in the principal slip zones of other active faults making resistivity logs a valuable tool for identifying these zones.

Causes and remedies for porosity in composite manufacturing

Science.gov (United States)

Fernlund, G.; Wells, J.; Fahrang, L.; Kay, J.; Poursartip, A.

2016-07-01

Porosity is a challenge in virtually all composite processes but in particular in low pressure processes such as out of autoclave processing of prepregs, where the maximum pressure is one atmosphere. This paper discusses the physics behind important transport phenomena that control porosity and how we can use our understanding of the underlying science to develop strategies to achieve low porosity for these materials and processes in an industrial setting. A three step approach is outlined that addresses and discusses: gas evacuation of trapped air, volatiles and off-gassing, and resin infiltration of evacuated void space.

Notional Permeability

NARCIS (Netherlands)

Kik, R.; Van den Bos, J.P.; Maertens, J.; Verhagen, H.J.; Van der Meer, J.W.

2012-01-01

Different layer design of a rock slope and under layers has a large effect on the strengths on the rock slope itself. In the stability formula developed of VAN DER MEER [1988] this effect is represented by the term Notional Permeability with symbol P. A more open, or permeable, structure underneath

Sensitivity studies on parameters affecting gas release from an underground rock cavern

International Nuclear Information System (INIS)

Schlueter, E.; Pruess, K.

1990-01-01

A series of numerical simulation experiments is performed to quantify the effects of the release and migration of non-condensible gas in water-saturated fractured rock formations. The relative importance of multiphase parameters such as relative permeability, capillary pressure, intrinsic permeability, and porosity on system behavior is studied. 10 refs., 28 figs., 5 tabs

Tomography based determination of permeability, Dupuit-Forchheimer coefficient, and interfacial heat transfer coefficient in reticulate porous ceramics

International Nuclear Information System (INIS)

Petrasch, Joerg; Meier, Fabian; Friess, Hansmartin; Steinfeld, Aldo

2008-01-01

A computer tomography based methodology is applied to determine the transport properties of fluid flow across porous media. A 3D digital representation of a 10-ppi reticulate porous ceramic (RPC) sample was generated by X-ray tomographic scans. Structural properties such as the porosity, specific interfacial surface area, pore-size distribution, mean survival time, two-point correlation function s 2 , and local geometry distribution of the RPC sample are directly extracted from the tomographic data. Reference solutions of the fluid flow governing equations are obtained for Re = 0.2-200 by applying finite volume direct pore-level numerical simulation (DPLS) using unstructured, body-fitted, tetrahedral mesh discretization. The permeability and the Dupuit-Forchheimer coefficient are determined from the reference solutions by DPLS, and compared to the values predicted by selected porous media flow models, namely: conduit-flow, hydraulic radius theory, drag models, mean survival time bound, s 2 -bound, fibrous bed correlations, and local porosity theory-based models. DPLS is further employed to determine the interfacial heat transfer coefficient and to derive a corresponding Nu-correlation, which is compared to empirical correlations

Negative permeability from random particle composites

Energy Technology Data Exchange (ETDEWEB)

Hussain, Shahid, E-mail: shussain2@qinetiq.com

2017-04-15

Artificial media, such as those composed of periodically-spaced wires for negative permittivity and split ring resonators for negative permeability have been extensively investigated for negative refractive index (NRI) applications (Smith et al., 2004; Pendry et al., 1999) [1,2]. This paper presents an alternative method for producing negative permeability: granular (or particulate) composites incorporating magnetic fillers. Artificial media, such as split-ring resonators, are designed to produce a magnetic resonance feature, which results in negative permeability over a narrow frequency range about the resonance frequency. The position of the feature is dependent upon the size of the inclusion. The material in this case is anisotropic, such that the feature is only observable when the materials are orientated in a specific direction relative to the applied field. A similar resonance can be generated in magnetic granular (particulate) materials: ferromagnetic resonance from the natural spin resonance of particles. Although the theoretical resonance profiles in granular composites shows the permeability dipping to negative values, this is rarely observed experimentally due to resonance damping effects. Results are presented for iron in spherical form and in flake form, dispersed in insulating host matrices. The two particle shapes show different permeability performance, with the magnetic flakes producing a negative contribution. This is attributed to the stronger coupling with the magnetic field resulting from the high aspect ratio of the flakes. The accompanying ferromagnetic resonance is strong enough to overcome the effects of damping and produce negative permeability. The size of random particle composites is not dictated by the wavelength of the applied field, so the materials are potentially much thinner than other, more traditional artificial composites at microwave frequencies. - Highlights: • Negative permeability from random particle composites is

High-permeability criterion for BCS classification: segmental/pH dependent permeability considerations.

Science.gov (United States)

Dahan, Arik; Miller, Jonathan M; Hilfinger, John M; Yamashita, Shinji; Yu, Lawrence X; Lennernäs, Hans; Amidon, Gordon L

2010-10-04

The FDA classifies a drug substance as high-permeability when the fraction of dose absorbed (F(abs)) in humans is 90% or higher. This direct correlation between human permeability and F(abs) has been recently controversial, since the β-blocker sotalol showed high F(abs) (90%) and low Caco-2 permeability. The purpose of this study was to investigate the scientific basis for this disparity between permeability and F(abs). The effective permeabilities (P(eff)) of sotalol and metoprolol, a FDA standard for the low/high P(eff) class boundary, were investigated in the rat perfusion model, in three different intestinal segments with pHs corresponding to the physiological pH in each region: (1) proximal jejunum, pH 6.5; (2) mid small intestine, pH 7.0; and (3) distal ileum, pH 7.5. Both metoprolol and sotalol showed pH-dependent permeability, with higher P(eff) at higher pH. At any given pH, sotalol showed lower permeability than metoprolol; however, the permeability of sotalol determined at pH 7.5 exceeded/matched metoprolol's at pH 6.5 and 7.0, respectively. Physicochemical analysis based on ionization, pK(a) and partitioning of these drugs predicted the same trend and clarified the mechanism behind these observed results. Experimental octanol-buffer partitioning experiments confirmed the theoretical curves. An oral dose of metoprolol has been reported to be completely absorbed in the upper small intestine; it follows, hence, that metoprolol's P(eff) value at pH 7.5 is not likely physiologically relevant for an immediate release dosage form, and the permeability at pH 6.5 represents the actual relevant value for the low/high permeability class boundary. Although sotalol's permeability is low at pH 6.5 and 7.0, at pH 7.5 it exceeds/matches the threshold of metoprolol at pH 6.5 and 7.0, most likely responsible for its high F(abs). In conclusion, we have shown that, in fact, there is no discrepancy between P(eff) and F(abs) in sotalol's absorption; the data emphasize that

The use of multi-energy-group neutron diffusion theory to numerically evaluate the relative utility of three dial-detector neutron porosity well logging tools

International Nuclear Information System (INIS)

Zalan, T.A.

1988-01-01

Multi-energy-group neutron diffusion theory is used to numerically evaluate the utility of two different dual-detector neutron porosity logging devices, a 14 MeV (accelerator) neutron source - epithermal neutron detector device and a 4 MeV neutron source - capture gamma-ray detector device, relative to the traditional 4 MeV neutron source - thermal neutron detector device. Fast and epithermal neutron diffusion parameters are calculated using Monte Carlo - derived neutron flux distributions. Thermal parameters are calculated from tabulated cross sections. An existing analytical method to describe the transport of gamma-rays through common earth materials is modified in order to accommodate the modeling of the 4 MeV neutron - capture gamma-ray device. The 14 MeV neutron - epithermal neutron device is found to be less sensitive to porosity than the 4 MeV neutron - capture gamma-ray device, which in turn is found to be less sensitive to porosity than the traditional 4 MeV neutron - thermal neutron device. Salinity effects are found to be comparable for the 4 MeV neutron - capture gamma-ray and 4 MeV neutron - thermal neutron devices. The 4 MeV neutron capture gamma-ray measurement is found to be deepest investigating

Ultrasonic technique for measuring porosity of plasma-sprayed alumina coatings

Science.gov (United States)

Parthasarathi, S.; Tittmann, B. R.; Onesto, E. J.

1997-12-01

Porosity is an important factor in plasma-sprayed coatings, especially ceramic coatings. Excessive poros-ity can adversely affect the performance of the coated component in various ways. An ultrasonic nonde-structive measurement technique has been developed to measure porosity in plasma-sprayed alumina coatings. The technique is generic and can be extended to other ceramic coating systems. To test the tech-nique, freestanding alumina coatings with varying levels of porosity were fabricated via plasma spray. Samples with varying porosity, obtained through innovative fabrication techniques, were used to gener-ate a calibration curve. The ultrasonic velocity in the low-frequency range was found to be dependent on the density of freestanding coatings (measured via Archimedian techniques). This dependence is the basis of the development of a technique to measure the density of coatings.

Controlling DC permeability in cast steels

Energy Technology Data Exchange (ETDEWEB)

Sumner, Aaran, E-mail: aaran.sumner@nottingham.ac.uk [University of Nottingham, Nottingham University Park Campus, Nottingham NG7 2RD, England (United Kingdom); Gerada, Chris, E-mail: chris.gerada@nottingham.ac.uk [Electrical Machines, University of Nottingham, Tower Building, Nottingham NG7 2RD, England (United Kingdom); Brown, Neil, E-mail: neil.brown@cummins.com [Advanced Electrical Machines Research and Technology at Cummins Power Generation, Peterborough PE2 6FZ, England (United Kingdom); Clare, Adam, E-mail: adam.clare@nottingham.ac.uk [Advanced Manufacturing, University of Nottingham, University Park Campus, Nottingham NG7 2RD, England (United Kingdom)

2017-05-01

Annealing (at multiple cooling rates) and quenching (with tempering) was performed on specimens of cast steel of varying composition. The aim was to devise a method for selecting the steel with the highest permeability, from any given range of steels, and then increasing the permeability by heat treatment. Metallographic samples were imaged using optical microscopy to show the effect of the applied heat treatments on the microstructure. Commonly cast steels can have DC permeability altered by the careful selection of a heat treatment. Increases of up to 381% were achieved by annealing using a cooling rate of 6.0 °C/min. Annealing was found to cause the carbon present in the steel to migrate from grain boundaries and from within ferrite crystals into adjacent pearlite crystals. The migration of the carbon resulted in less carbon at grain boundaries and within ferrite crystals reducing the number of pinning sites between magnetic domains. This gives rise to a higher permeability. Quenching then tempering was found to cause the formation of small ferrite crystals with the carbon content of the steel predominately held in the martensitic crystal structures. The results show that with any given range of steel compositions the highest baseline DC permeability will be found with the steel that has the highest iron content and the lowest carbon content. For the samples tested in this paper a cooling rate of 4.5 °C/min resulted in the relative permeability of the sample with the highest baseline permeability, AS4, increasing from 783 to 1479 at 0.5 T. This paper shows how heat treatments commonly applied to hypoeutectoid cast steels, to improve their mechanical performance, can be used to also enhance electromagnetic properties of these alloys. The use of cast steels allows the creation of DC components for electrical machines not possible by the widely used method of stacking of electrical grade sheet steels. - Highlights: • A range of structural steels had their

Controlling DC permeability in cast steels

International Nuclear Information System (INIS)

Sumner, Aaran; Gerada, Chris; Brown, Neil; Clare, Adam

2017-01-01

Annealing (at multiple cooling rates) and quenching (with tempering) was performed on specimens of cast steel of varying composition. The aim was to devise a method for selecting the steel with the highest permeability, from any given range of steels, and then increasing the permeability by heat treatment. Metallographic samples were imaged using optical microscopy to show the effect of the applied heat treatments on the microstructure. Commonly cast steels can have DC permeability altered by the careful selection of a heat treatment. Increases of up to 381% were achieved by annealing using a cooling rate of 6.0 °C/min. Annealing was found to cause the carbon present in the steel to migrate from grain boundaries and from within ferrite crystals into adjacent pearlite crystals. The migration of the carbon resulted in less carbon at grain boundaries and within ferrite crystals reducing the number of pinning sites between magnetic domains. This gives rise to a higher permeability. Quenching then tempering was found to cause the formation of small ferrite crystals with the carbon content of the steel predominately held in the martensitic crystal structures. The results show that with any given range of steel compositions the highest baseline DC permeability will be found with the steel that has the highest iron content and the lowest carbon content. For the samples tested in this paper a cooling rate of 4.5 °C/min resulted in the relative permeability of the sample with the highest baseline permeability, AS4, increasing from 783 to 1479 at 0.5 T. This paper shows how heat treatments commonly applied to hypoeutectoid cast steels, to improve their mechanical performance, can be used to also enhance electromagnetic properties of these alloys. The use of cast steels allows the creation of DC components for electrical machines not possible by the widely used method of stacking of electrical grade sheet steels. - Highlights: • A range of structural steels had their

Porosity Variation in Cenozoic and Upper Chalk from the Ontong Java Pleateau

DEFF Research Database (Denmark)

Borre, Mai Kirstine

1997-01-01

Porosity was obtained from matrix- and intraparticle porosity assessed from image analysis of backscattered electron micrographs of 3000x and 300x magnification. Comparing porosity assessed from image analysis with porosity measured by index properties, it was seen that image analysis data at 300...

The complex initial reluctivity, permeability and susceptibility spectra of magnetic materials

Science.gov (United States)

Hamilton, N. C.

2015-03-01

The HF complex permeability spectrum of a magnetic material is deduced from the measured impedance spectrum, which is then normalized to a series permeability spectrum. However, this series permeability spectrum has previously been shown to correspond to a parallel magnetic circuit, which is not appropriate. Some of the implications of this truth are examined. This electric/magnetic duality has frustrated efforts to interpret the shape of the complex magnetic permeability spectra of materials, and has hindered the application of impedance spectroscopy to magnetic materials. In the presence of magnetic loss, the relationship between the relative magnetic permeability and the magnetic susceptibility is called into question. The use of reluctivity spectra for expressing magnetic material properties is advocated. The relative loss factor, tanδm/μi is shown to be an approximation for the imaginary part of the reluctivity. A single relaxation model for the initial reluctivity spectra of magnetic materials is presented, and its principles are applied to measurements of a high permeability ferrite. The results are presented as contour plots of the spectra as a function of temperature.

Pore-level determination of spectral reflection behaviors of high-porosity metal foam sheets

Science.gov (United States)

Li, Yang; Xia, Xin-Lin; Ai, Qing; Sun, Chuang; Tan, He-Ping

2018-03-01

Open cell metal foams are currently attracting attention and their radiative behaviors are of primary importance in high temperature applications. The spectral reflection behaviors of high-porosity metal foam sheets, bidirectional reflectance distribution function (BRDF) and directional-hemispherical reflectivity were numerically investigated. A set of realistic nickel foams with porosity from 0.87 to 0.97 and pore density from 10 to 40 pores per inch were tomographied to obtain their 3-D digital cell network. A Monte Carlo ray-tracing method was employed in order to compute the pore-level radiative transfer inside the network within the limit of geometrical optics. The apparent reflection behaviors and their dependency on the textural parameters and strut optical properties were comprehensively computed and analysed. The results show a backward scattering of the reflected energy at the foam sheet surface. Except in the cases of large incident angles, an energy peak is located almost along the incident direction and increases with increasing incident angles. Through an analytical relation established, the directional-hemispherical reflectivity can be related directly to the porosity of the foam sheet and to the complex refractive index of the solid phase as well as the specularity parameter which characterizes the local reflection model. The computations show that a linear decrease in normal-hemispherical reflectivity occurs with increasing porosity. The rate of this decrease is directly proportional to the strut normal reflectivity. In addition, the hemispherical reflectivity increases as a power function of the incident angle cosine.

A Study on Porosity Distribution in Nanoporous TiO2 Photoelectrodes for Output Performance of Dye-Sensitized Solar Cells

International Nuclear Information System (INIS)

Wei-Wei, Xu; Xiang-Dong, Luo; Wei-Ping, Jing; Lin-Hua, Hu; Song-Yuan, Dai; Chang-Neng, Zhang

2010-01-01

Porosity as one of the crucial factors to film morphology affects the overall electrical current-voltage characteristics of dye-sensitized solar cell (DSC). We search for the short-circuit current density, the open-circuit voltage and the maximum power output as the main functional parameters of DSC closely related to porosity under different film thickness. The theoretical analyses show some exciting results. As porosity changes from 0.41 to 0.75, the short-circuit current density shows the optimal value when the film thickness is 8–10 μm. The open-circuit voltage presents different variation tendencies for the film thicknesses within 1–8 μm and within 10–30 μm. The porosity is near 0.41 and the film thickness is about 10 μm, DSC will have the maximum power output. The theoretical studies also illustrate that given a good porosity distribution, DSC can obtain an excellent short-circuit current characteristic, which agrees well with the experimental results reported in previous literature. (cross-disciplinary physics and related areas of science and technology)

Theory and test research on permeability of coal and rock body influenced by mining

Energy Technology Data Exchange (ETDEWEB)

Qing-xin Qi; Hong-yan Li; You-gang Wang; Zhi-gang Deng; Hang Lan; Yong-wei Peng; Chun-rui Li [China Coal Research Institute, Beijing (China)

2009-06-15

Stress distribution rules and deformation and failure properties of coal and rock bodies influenced by mining were analyzed. Experimental research on permeability of coal and rock samples under different loading conditions was finished in the laboratory. In-situ measurement of coal permeability influenced by actual mining was done as well. Theory analysis show that permeability varied with damage development of coal and rock under stress, and the influence of fissure on permeability was greatest. Laboratory results show that under different loading conditions permeability was different and it varied with stress, which indicated that permeability was directly related to the loading process. In-situ tests showed that permeability is related to abutment stress to some degree. The above results may be referenced to gas prevention and drainage. 11 refs., 6 figs., 1 tab.

Porosity in Ocean Racing Yacht Composites: a Review

Science.gov (United States)

Baley, Christophe; Lan, Marine; Davies, Peter; Cartié, Denis

2015-02-01

Ocean racing yachts are mainly manufactured from carbon/epoxy composites similar to those used by the aeronautical industry but, with some exceptions such as masts, these structures are not produced in autoclaves. This leads to the presence of higher porosity levels. This paper will first present the different types of porosity found in traditional racing yacht structures. Difficulties in evaluating defect levels will then be discussed and published work characterizing the influence of defects will be reviewed. Current developments to improve racing yacht composite quality such as thin ply technology, out-of-autoclave processing and automated fibre placement will then be described, and their implications for porosity will be discussed.

Permeability measuremens of brazilian Eucalyptus

Directory of Open Access Journals (Sweden)

Marcio Rogério da Silva

2010-09-01

Full Text Available The permeability of Brazilian Eucalyptus grandis and Eucalyptus citriodora wood was measured in a custom build gas analysis chamber in order to determine which species could be successfully treated with preservatives. Liquid permeability was tested using an emulsion of Neen oil and a control of distillated water. Air was used to test the gas phase permeability. For both Eucalyptus grandis and Eucalyptus citriodora, the longitudinal permeability of gas was shown to be about twice as great as the liquid phase permeability. No radial permeability was observed for either wood. The permeability of air and water through the sapwood of Eucalyptus grandis was greater than that through the sapwood of Eucalyptus citriodora. The permeability of neen oil preservative through the sapwood of Eucalyptus grandis was also greater than through the sapwood of E. Citradora, but the difference was not statistically significant. Scanning Electron Microscopy images showed that the distribution and obstruction in the vessels could be correlated with observed permeability properties. Irrespective of the causes of differences in permeability between the species, the fluid phase flux through the sapwood of both species was significant, indicating that both Eucalyptus grandis and Eucalyptus citriodora could be successfully treated with wood preservative.

Three frequency modulated combination thermal neutron lifetime log and porosity

International Nuclear Information System (INIS)

Paap, H.J.; Arnold, D.M.; Smith, M.P.

1976-01-01

Methods are disclosed for measuring simultaneously the thermal neutron lifetime of the borehole fluid and earth formations in the vicinity of a well borehole, together with the formation porosity. A harmonically intensity modulated source of fast neutrons is used to irradiate the earth formations with fast neutrons at three different modulation frequencies. Intensity modulated clouds of thermal neutrons at each of the three modulation frequencies are detected by dual spaced detectors and the relative phase shift of the thermal neutrons with respect to the fast neutrons is determined at each of the three modulation frequencies at each detector. These measurements are then combined to determine simultaneously the thermal neutron decay time of the borehole fluid, the thermal neutron decay time of surrounding earth formation media and the porosity of the formation media

Solute transport processes in a highly permeable fault zone of Lindau fractured rock test site (Germany)

Energy Technology Data Exchange (ETDEWEB)

Himmelsbach, T. [Ruhr-Univ., Bochum (Germany). Dept. of Applied Geology; Hoetzl, H. [Univ. of Karlsruhe (Germany). Dept. of Applied Geology; Maloszewski, P. [GSF-Inst. for Hydrology, Munich-Neuherberg (Germany)

1998-09-01

The results of field tracer experiments performed in the Lindau fractured rock test site (southern Black Forest, Germany) and subsequent modeling are presented. A vertical, hydrothermally mineralized fault zone, with a permeability much greater than the surrounding granite mass, lies beneath a planned dam site. A dense network of boreholes and tunnels were used to investigate scaling effects of solute transport processes in fractured rock. A series of tracer experiments using deuterium and dye tracers were performed over varying distances and under different testing procedures, resulting in different flow field conditions. Large-scale tracer experiments were performed under natural flow field conditions, while small-scale tracer experiments were performed under artificially induced radial-convergent and injection-withdrawal flow fields. The tracer concentration curves observed in all experiments were strongly influenced by the matrix diffusion. The curves were evaluated with the one-dimensional single fissure dispersion model (SFDM) adjusted for the different flow field conditions. The fitting model parameters found determined the fracture aperture, and matrix and fissure porosities. The determined fracture aperture varied between the sections having different hydraulic conductivity. The determined values of matrix porosity seemed to be independent of the scale of the experiment. The modeled matrix porosities agreed well with values determined in independent laboratory investigations of drill cores using mercury porosimetry. In situ fissure porosity, determined only in small-scale experiments, was independent of the applied geometry of the artificially induced flow fields. The dispersivities were found to be independent of the scale of experiment but dependent on the flow conditions. The values found in forced gradient tests lie between 0.2 and 0.3 m, while values in experiments performed under natural flow conditions were one order of magnitude higher.

A relative permeability model to derive fractional-flow functions of water-alternating-gas and surfactant-alternating-gas foam core-floods

International Nuclear Information System (INIS)

Al-Mossawy, Mohammed Idrees; Demiral, Birol; Raja, D M Anwar

2013-01-01

Foam is used in enhanced oil recovery to improve the sweep efficiency by controlling the gas mobility. The surfactant-alternating-gas (SAG) foam process is used as an alternative to the water-alternating-gas (WAG) injection. In the WAG technique, the high mobility and the low density of the gas lead the gas to flow in channels through the high permeability zones of the reservoir and to rise to the top of the reservoir by gravity segregation. As a result, the sweep efficiency decreases and there will be more residual oil in the reservoir. The foam can trap the gas in liquid films and reduces the gas mobility. The fractional-flow method describes the physics of immiscible displacements in porous media. Finding the water fractional flow theoretically or experimentally as a function of the water saturation represents the heart of this method. The relative permeability function is the conventional way to derive the fractional-flow function. This study presents an improved relative permeability model to derive the fractional-flow functions for WAG and SAG foam core-floods. The SAG flow regimes are characterized into weak foam, strong foam without a shock front and strong foam with a shock front. (paper)

Radiographically detectable intracortical porosity

International Nuclear Information System (INIS)

Meema, H.E.

1986-01-01

Since the measurement of intracortical resorptive spaces by histologic methods is difficult and very few data are available in normal humans, we have measured their lengths and widths and calculated the intracortical porosity in metacarpals and phalanges of 79 normal women and 69 normal men, using fine-detail radiographs of the hands and a computerized semi-automatic image analysis system (Zeiss MOP-3), this being the first study of this kind. Several methodological problems were solved satisfactorily, and the results of this study could serve as a data bank for further investigations concerned with intracortical resorption. Significant differences were found between age and sex versus several intracortical resorptive parameters; also significant correlations were found with age in some cases. Normal intracortical porosity was found to be about three times greater in the proximal phalanges than in the metacarpals. It is concluded that this methodology could be used for further studies of intracortical resorption in osteoporosis and other metabolic bone diseases. (orig.)

Porosity of porcine bladder acellular matrix: impact of ACM thickness.

Science.gov (United States)

Farhat, Walid; Chen, Jun; Erdeljan, Petar; Shemtov, Oren; Courtman, David; Khoury, Antoine; Yeger, Herman

2003-12-01

The objectives of this study are to examine the porosity of bladder acellular matrix (ACM) using deionized (DI) water as the model fluid and dextran as the indicator macromolecule, and to correlate the porosity to the ACM thickness. Porcine urinary bladders from pigs weighing 20-50 kg were sequentially extracted in detergent containing solutions, and to modify the ACM thickness, stretched bladders were acellularized in the same manner. Luminal and abluminal ACM specimens were subjected to fixed static DI water pressure (10 cm); and water passing through the specimens was collected at specific time interval. While for the macromolecule porosity testing, the diffusion rate and direction of 10,000 MW fluoroescein-labeled dextrans across the ACM specimens mounted in Ussing's chambers were measured. Both experiments were repeated on the thin stretched ACM. In both ACM types, the fluid porosity in both directions did not decrease with increased test duration (3 h); in addition, the abluminal surface was more porous to fluid than the luminal surface. On the other hand, when comparing thin to thick ACM, the porosity in either direction was higher in the thick ACM. Macromolecule porosity, as measured by absorbance, was higher for the abluminal thick ACM than the luminal side, but this characteristic was reversed in the thin ACM. Comparing thin to thick ACM, the luminal side in the thin ACM was more porous to dextran than in the thick ACM, but this characteristic was reversed for the abluminal side. The porcine bladder ACM possesses directional porosity and acellularizing stretched urinary bladders may increase structural density and alter fluid and macromolecule porosity. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 970-974, 2003

Homogeneity vs. Heterogeneity of Porosity in Boom Clay

International Nuclear Information System (INIS)

Hemes, Susanne; Desbois, Guillaume; Urai, Janos L.; De Craen, Mieke; Honty, Miroslav

2013-01-01

Microstructural investigations on Boom Clay at nano- to micrometer scale, using BIB-SEM methods, result in porosity characterization for different mineral phases from direct observations on high resolution SE2-images of representative elementary areas (REAs). High quality, polished surfaces of cross-sections of ∼ 1 mm 2 size were produced on three different samples from the Mol-Dessel research site (Belgium). More than 33,000 pores were detected, manually segmented and analyzed with regard to their size, shape and orientation. Two main pore classes were defined: Small pores (< 500 nm (ED)) within the clay matrices of samples and =big' pores (> 500 nm (ED)) at the interfaces between clay and non-clay mineral (NCM) grains. Samples investigated show similar porosities regarding the first pore-class, but differences occur at the interfaces between clay matrix and NCM grains. These differences were interpreted to be due to differences in quantitative mineralogy (amount of non-clay mineral grains) and grain-size distributions between samples investigated. Visible porosities were measured as 15 to 17 % for samples investigated. Pore-size distributions of pores in clay are similar for all samples, showing log-normal distributions with peaks around 60 nm (ED) and more than 95 % of the pores being smaller than 500 nm (ED). Fitting pore-size distributions using power-laws with exponents between 1.56 and 1.7, assuming self-similarity of the pore space, thus pores smaller than the pore detection resolution following the same power-laws and using these power-laws for extrapolation of pore-size distributions below the limit of pore detection resolution, results in total estimated porosities between 20 and 30 %. These results are in good agreement with data known from Mercury Porosimetry investigations (35-40 % porosity) and water content porosity measurements (∼ 36 %) performed on Boom Clay. (authors)

Reservoir simulation with MUFITS code: Extension for double porosity reservoirs and flows in horizontal wells

Science.gov (United States)

Afanasyev, Andrey

2017-04-01

Numerical modelling of multiphase flows in porous medium is necessary in many applications concerning subsurface utilization. An incomplete list of those applications includes oil and gas fields exploration, underground carbon dioxide storage and geothermal energy production. The numerical simulations are conducted using complicated computer programs called reservoir simulators. A robust simulator should include a wide range of modelling options covering various exploration techniques, rock and fluid properties, and geological settings. In this work we present a recent development of new options in MUFITS code [1]. The first option concerns modelling of multiphase flows in double-porosity double-permeability reservoirs. We describe internal representation of reservoir models in MUFITS, which are constructed as a 3D graph of grid blocks, pipe segments, interfaces, etc. In case of double porosity reservoir, two linked nodes of the graph correspond to a grid cell. We simulate the 6th SPE comparative problem [2] and a five-spot geothermal production problem to validate the option. The second option concerns modelling of flows in porous medium coupled with flows in horizontal wells that are represented in the 3D graph as a sequence of pipe segments linked with pipe junctions. The well completions link the pipe segments with reservoir. The hydraulics in the wellbore, i.e. the frictional pressure drop, is calculated in accordance with Haaland's formula. We validate the option against the 7th SPE comparative problem [3]. We acknowledge financial support by the Russian Foundation for Basic Research (project No RFBR-15-31-20585). References [1] Afanasyev, A. MUFITS Reservoir Simulation Software (www.mufits.imec.msu.ru). [2] Firoozabadi A. et al. Sixth SPE Comparative Solution Project: Dual-Porosity Simulators // J. Petrol. Tech. 1990. V.42. N.6. P.710-715. [3] Nghiem L., et al. Seventh SPE Comparative Solution Project: Modelling of Horizontal Wells in Reservoir Simulation

Does nutrition affect bone porosity and mineral tissue distribution in deer antlers? The relationship between histology, mechanical properties and mineral composition.

Science.gov (United States)

Landete-Castillejos, T; Currey, J D; Ceacero, F; García, A J; Gallego, L; Gomez, S

2012-01-01

It is well known that porosity has an inverse relationship with the mechanical properties of bones. We examined cortical and trabecular porosity of antlers, and mineral composition, thickness and mechanical properties in the cortical wall. Samples belonged to two deer populations: a captive population of an experimental farm having a high quality diet, and a free-ranging population feeding on plants of lower nutritive quality. As shown for minerals and mechanical properties in previous studies by our group, cortical and trabecular porosity increased from the base distally. Cortical porosity was always caused by the presence of incomplete primary osteons. Porosity increased along the length of the antler much more in deer with lower quality diet. Despite cortical porosity being inversely related to mechanical properties and positively with K, Zn and other minerals indicating physiological effort, it was these minerals and not porosity that statistically better explained variability in mechanical properties. Histochemistry showed that the reason for this is that Zn is located around incomplete osteons and also in complete osteons that were still mineralizing, whereas K is located in non-osteonal bone, which constitutes a greater proportion of bone where osteons are incompletely mineralized. This suggests that, K, Zn and other minerals indicate reduction in mechanical performance even with little porosity. If a similar process occurred in internal bones, K, Zn and other minerals in the bone may be an early indicator of decrease in mechanical properties and future osteoporosis. In conclusion, porosity is related to diet and physiological effort in deer. Copyright © 2011 Elsevier Inc. All rights reserved.

Breaking down the barriers: the gut microbiome, intestinal permeability and stress-related psychiatric disorders

Science.gov (United States)

Kelly, John R.; Kennedy, Paul J.; Cryan, John F.; Dinan, Timothy G.; Clarke, Gerard; Hyland, Niall P.

2015-01-01

The emerging links between our gut microbiome and the central nervous system (CNS) are regarded as a paradigm shift in neuroscience with possible implications for not only understanding the pathophysiology of stress-related psychiatric disorders, but also their treatment. Thus the gut microbiome and its influence on host barrier function is positioned to be a critical node within the brain-gut axis. Mounting preclinical evidence broadly suggests that the gut microbiota can modulate brain development, function and behavior by immune, endocrine and neural pathways of the brain-gut-microbiota axis. Detailed mechanistic insights explaining these specific interactions are currently underdeveloped. However, the concept that a “leaky gut” may facilitate communication between the microbiota and these key signaling pathways has gained traction. Deficits in intestinal permeability may underpin the chronic low-grade inflammation observed in disorders such as depression and the gut microbiome plays a critical role in regulating intestinal permeability. In this review we will discuss the possible role played by the gut microbiota in maintaining intestinal barrier function and the CNS consequences when it becomes disrupted. We will draw on both clinical and preclinical evidence to support this concept as well as the key features of the gut microbiota which are necessary for normal intestinal barrier function. PMID:26528128

Establishing the Relationship between Fracture-Related Dolomite and Primary Rock Fabric on the Distribution of Reservoirs in the Michigan Basin

Energy Technology Data Exchange (ETDEWEB)

G. Michael Grammer

2006-09-30

This topical report covers the year 2 of the subject 3-year grant, evaluating the relationship between fracture-related dolomite and dolomite constrained by primary rock fabric in the 3 most prolific reservoir intervals in the Michigan Basin (Ordovician Trenton-Black River Formations; Silurian Niagara Group; and the Devonian Dundee Formation). The characterization of select dolomite reservoirs has been the major focus of our efforts in Phase II/Year 2. Fields have been prioritized based upon the availability of rock data for interpretation of depositional environments, fracture density and distribution as well as thin section, geochemical, and petrophysical analyses. Structural mapping and log analysis in the Dundee (Devonian) and Trenton/Black River (Ordovician) suggest a close spatial relationship among gross dolomite distribution and regional-scale, wrench fault related NW-SE and NE-SW structural trends. A high temperature origin for much of the dolomite in the 3 studied intervals (based upon initial fluid inclusion homogenization temperatures and stable isotopic analyses,) coupled with persistent association of this dolomite in reservoirs coincident with wrench fault-related features, is strong evidence for these reservoirs being influenced by hydrothermal dolomitization. For the Niagaran (Silurian), a comprehensive high resolution sequence stratigraphic framework has been developed for a pinnacle reef in the northern reef trend where we had 100% core coverage throughout the reef section. Major findings to date are that facies types, when analyzed at a detailed level, have direct links to reservoir porosity and permeability in these dolomites. This pattern is consistent with our original hypothesis of primary facies control on dolomitization and resulting reservoir quality at some level. The identification of distinct and predictable vertical stacking patterns within a hierarchical sequence and cycle framework provides a high degree of confidence at this point

Compositional and Relative Permeability Hysteresis Effects on Near-Miscible WAG

DEFF Research Database (Denmark)

Christensen, Jes Reimer; Stenby, Erling Halfdan; Skauge, Arne

1998-01-01

Evaluation of compositional effects and fluid flow description on near-miscible (water-alternating-gas) WAG modeling have been studied for a North Sea oil field starting production in 1998. A sector model with four wells was applied to simulate a heterogeneous sandstone reservoir, and a compositi......Evaluation of compositional effects and fluid flow description on near-miscible (water-alternating-gas) WAG modeling have been studied for a North Sea oil field starting production in 1998. A sector model with four wells was applied to simulate a heterogeneous sandstone reservoir......, and a compositional model was used to compare different production strategies e.g. waterflooding and a near-miscible (WAG) injection. In the WAG scheme both dry and wet (rich) hydrocarbon gases have been considered for injection. The phase behaviour was quantified by comparing the performance of the different...... injection gases. Result obtained shows the WAG injection gives improved recovery compared to water injection, due to better sweep and lower residual oil saturation. Simulations with and without relative permeability hysteresis (two-phase model) were compared. The effect of trapped gas on oil recovery does...

Porosity estimation by semi-supervised learning with sparsely available labeled samples

Science.gov (United States)

Lima, Luiz Alberto; Görnitz, Nico; Varella, Luiz Eduardo; Vellasco, Marley; Müller, Klaus-Robert; Nakajima, Shinichi

2017-09-01

This paper addresses the porosity estimation problem from seismic impedance volumes and porosity samples located in a small group of exploratory wells. Regression methods, trained on the impedance as inputs and the porosity as output labels, generally suffer from extremely expensive (and hence sparsely available) porosity samples. To optimally make use of the valuable porosity data, a semi-supervised machine learning method was proposed, Transductive Conditional Random Field Regression (TCRFR), showing good performance (Görnitz et al., 2017). TCRFR, however, still requires more labeled data than those usually available, which creates a gap when applying the method to the porosity estimation problem in realistic situations. In this paper, we aim to fill this gap by introducing two graph-based preprocessing techniques, which adapt the original TCRFR for extremely weakly supervised scenarios. Our new method outperforms the previous automatic estimation methods on synthetic data and provides a comparable result to the manual labored, time-consuming geostatistics approach on real data, proving its potential as a practical industrial tool.

Optimization of High Porosity Thermal Barrier Coatings Generated with a Porosity Former

Czech Academy of Sciences Publication Activity Database

Medřický, J.; Curry, N.; Pala, Zdeněk; Vilémová, Monika; Chráska, Tomáš; Johansson, J.; Markocsan, N.

2015-01-01

Roč. 24, č. 4 (2015), s. 622-628 ISSN 1059-9630 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389021 Keywords : gas turbine s * high temperature application * porosity of coatings * stabilized zirconia * thermal barrier coatings (TBCs) Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.568, year: 2015

Effect of temperature and relative humidity on the water vapour permeability and mechanical properties of cassava starch and soy protein concentrate based edible films.

Science.gov (United States)

Chinma, C E; Ariahu, C C; Alakali, J S

2015-04-01

The effect of temperature and relative humidity on the water vapour permeability (WVP) and mechanical properties of cassava starch and soy protein concentrate (SPC) based edible films containing 20 % glycerol level were studied. Tensile strength and elastic modulus of edible films increased with increase in temperature and decreased with increase in relative humidity, while elongation at break decreased. Water vapour permeability of the films increased (2.6-4.3 g.mm/m(2).day.kPa) with increase in temperature and relative humidity. The temperature dependence of water vapour permeation of cassava starch-soy protein concentrate films followed Arrhenius relationship. Activation energy (Ea) of water vapour permeation of cassava starch-soy protein concentrate edible films ranged from 1.9 to 5.3 kJ/mol (R (2)  ≥ 0.93) and increased with increase in SPC addition. The Ea values were lower for the bio-films than for polyvinylidene chloride, polypropylene and polyethylene which are an indication of low water vapour permeability of the developed biofilms compared to those synthetic films.

Aging time on the aluminum basic acetate gel and its influence on the membrane permeability

International Nuclear Information System (INIS)

Clar, C; Scian, A. N; Aglietti, E.F

2003-01-01

Alumina ceramic membranes are new materials with important applications in separation processes with low energy requirements, high selectivity and ability to work at high and low temperatures.The preparation of alumina ceramic membranes from hydrates or aluminum salts as precursors implies obtaining a system of controlled porosity with a suitable mechanical resistance as well as the densification of the material thanks to the stable phases remaining after the thermal treatment.The metal carboxylates are potential precursors for the deposition and the subsequent formation of oxides at low temperatures.Aluminum basic acetate gel was synthesised in this work from commercial pseudobohemite. The influence of the aging time on the composition, crystalline structure and transition temperatures of the phases on the carboxylate was studied by XRD and DTA-TG.From suspensions of this aged gel at different times alumina ceramic membranes were prepared by dipcoating on different α-Al 2 O 3 supports and the influence of aging on the permeability of those membranes face to N 2 was also studied. It was observed that this is a parameter to be considered as it determines the thickness, permeability and integrity of the membranes

Ultrasonic maps of porosity in aluminum castings

International Nuclear Information System (INIS)

Ghaffari, Bita; Potter, Timothy J.; Mozurkewich, George

2002-01-01

The use of cast aluminum in the automotive industry has grown dramatically in recent years, leading to increased need for quantitative characterization of microporosity. As previously reported in the literature, the attenuation of ultrasound can be used to measure the porosity volume fraction and the mean pore size. An immersion ultrasound system has been built utilizing this technique to scan castings with high spatial resolution. Maps of attenuation are shown to locate areas of varying porosity readily and reliably

Regularities in eliminating the porosity in some crystalline and amorphous materials

International Nuclear Information System (INIS)

Betekhtin, V.I.; Kadomtsev, A.G.; Amosova, O.V.

2003-01-01

The results of the number of studies on eliminating the porosity under the effect of increased temperatures and pressures performed on the cast alloys (VT5L; AL2), steels (30KhG5N2A) and amorphous alloys (Co 59 Fe 5 Si 11 Ni 10 B 15 , Fe 61 Co 20 Si 5 B 14 , Fe 77 Ni 1 Si 9 B 13 ) are considered. The change in the porosity parameters was controlled through the small-angle X-ray scattering electron microscopy. It is shown that the effect of the hydrostatic pressure leads to decrease in the excessive free volume in the amorphous alloys, related to the availability of the micropores of about 10 nm dimensions and consequently to the increase in the strength, microhardness and temperature of the viscous-brittle transition. It is noted that the acting forces of the microporosity elimination may be related both to the internal stress and the Laplace pressure conditioned by the pores surface curvature [ru

Study on road surface source pollution controlled by permeable pavement

Science.gov (United States)

Zheng, Chaocheng

2018-06-01

The increase of impermeable pavement in urban construction not only increases the runoff of the pavement, but also produces a large number of Non-Point Source Pollution. In the process of controlling road surface runoff by permeable pavement, a large number of particulate matter will be withheld when rainwater is being infiltrated, so as to control the source pollution at the source. In this experiment, we determined the effect of permeable road surface to remove heavy pollutants in the laboratory and discussed the related factors that affect the non-point pollution of permeable pavement, so as to provide a theoretical basis for the application of permeable pavement.

Permeability changes due to mineral diagenesis in fractured crust: implications for hydrothermal circulation at mid-ocean ridges

Science.gov (United States)

Fontaine, Fabrice Jh.; Rabinowicz, Michel; Boulègue, Jacques

2001-01-01

The hydrothermal processes at ridge crests have been extensively studied during the last two decades. Nevertheless, the reasons why hydrothermal fields are only occasionally found along some ridge segments remain a matter of debate. In the present study we relate this observation to the mineral precipitation induced by hydrothermal circulation. Our study is based on numerical models of convection inside a porous slot 1.5 km high, 2.25 km long and 120 m wide, where seawater is free to enter and exit at its top while the bottom is held at a constant temperature of 420°C. Since the fluid circulation is slow and the fissures in which seawater circulates are narrow, the reactions between seawater and the crust achieve local equilibrium. The rate of mineral precipitation or dissolution is proportional to the total derivative of the temperature with respect to time. Precipitation of minerals reduces the width of the fissures and thus percolation. Using conventional permeability versus porosity laws, we evaluate the evolution of the permeability field during the hydrothermal circulation. Our computations begin with a uniform permeability and a conductive thermal profile. After imposing a small random perturbation on the initial thermal field, the circulation adopts a finger-like structure, typical of convection in vertical porous slots thermally influenced by surrounding walls. Due to the strong temperature dependence of the fluid viscosity and thermal expansion, the hot rising fingers are strongly buoyant and collide with the top cold stagnant water layer. At the interface of the cold and hot layers, a horizontal boundary layer develops causing massive precipitation. This precipitation front produces a barrier to the hydrothermal flow. Consequently, the flow becomes layered on both sides of the front. The fluid temperature at the top of the layer remains quite low: it never exceeds a temperature of 80°C, well below the exit temperature of hot vent sites observed at

A new water permeability measurement method for unsaturated tight materials using saline solutions

International Nuclear Information System (INIS)

Malinsky, Laurent; Talandier, Jean

2012-01-01

Document available in extended abstract form only. Relative water permeability of material in a radioactive waste disposal is a key parameter to simulate and predict saturation state evolution. In this paper we present a new measurement method and the results obtained for Callovo-Oxfordian (Cox) clay-stone, host rock of the underground Andra laboratory at Bure (Meuse/Haute-Marne). Relative water permeability of such a low permeability rock as Cox clay-stone has been measured up to now by an indirect method. It consists in submitting a rock sample to successive relative humidity steps imposed by saline solutions. The transient mass variation during each step and the mass at hydric equilibrium are interpreted generally by using an inverse analysis method. The water relative permeability function of water saturation is derived from water diffusion coefficient evolution and water retention curve. The proposed new method consists in directly measuring the water flux across a flat cylindrical submitted to a relative humidity gradient. Two special cells have been developed. The tightness of the lateral sample surface is insured by crushing a polyurethane ring surrounding the sample set in an aluminium device placed over a Plexiglas vessel filled with a saline solution. One of the cells is designed to allow humidity measurement in the cell. These cells can also be used to measure the relative humidity produced by a saline solution or by an unsaturated material. During a permeability measurement, the cell with the sample to be tested is continuously weighted in a Plexiglas box in which a saline solution imposes a different relative humidity at the upper sample face. The experimental set-up is shown on Figure 1. The mean permeability of the sample is proportional to the rate of mass variation when steady state is reached. The result of one test is shown on Figure 2(a). Twenty four permeability measurements have been performed on four argillite samples of 15 mm in height and

Measurement of the open porosity of agricultural soils with acoustic waves

Science.gov (United States)

Luong, Jeanne; Mercatoris, Benoit; Destain, Marie-France

2015-04-01

The space between agricultural soil aggregates is defined as structural porosity. It plays important roles in soil key functions that an agricultural soil performs in the global ecosystem. Porosity is one of the soil properties that affect plant growth along with soil texture, aggregate size, aeration and water holding capacity (Alaoui et al. 2011). Water supplies regulation of agricultural soil is related to the number of very small pores present in a soil due to the effect of capillarity. Change of porosity also affect the evaporation of the water on the surface (Le Maitre et al. 2014). Furthermore, soil is a habitat for soils organisms, and most living organisms, including plant roots and microorganisms require oxygen. These organisms breathe easier in a less compacted soil with a wide range of pores sizes. Soil compaction by agricultural engine degrades soil porosity. At the same time, fragmentation with tillage tools, creation of cracks due to wetting/drying and freezing/thawing cycles and effects of soil fauna can regenerate soil porosity. Soil compaction increases bulk density since soil grains are rearranged decreasing void space and bringing them into closer contact (Hamza & Anderson 2005). Drainage is reduced, erosion is facilitated and crop production decreases in a compacted soil. Determining soil porosity, giving insight on the soil compaction, with the aim to provide advices to farmers in their soil optimization towards crop production, is thus an important challenge. Acoustic wave velocity has been correlated to the porosity and the acoustic attenuation to the water content (Oelze et al. 2002). Recent studies have shown some correlations between the velocity of acoustic waves, the porosity and the stress state of soil samples (Lu et al. 2004; Lu 2005; Lu & Sabatier 2009), concluding that the ultrasonic waves are a promising tool for the rapid characterisation of unsaturated porous soils. Propagation wave velocity tends to decrease in a high porous

Mathematical Model to Predict the Permeability of Water Transport in Concrete Structure

OpenAIRE

Solomon Ndubuisi Eluozo

2013-01-01

Mathematical model to predict the permeability of water transport in concrete has been established, the model is to monitor the rate of water transport in concrete structure. The process of this water transport is based on the constituent in the mixture of concrete. Permeability established a relation on the influence of the micropores on the constituent that made of concrete, the method of concrete placement determine the rate of permeability deposition in concrete structure, permeability es...

Tailoring the porosity of hierarchical zeolites by carbon-templating

DEFF Research Database (Denmark)

Zhu, Kake; Egeblad, Kresten; Christensen, Claus H.

2008-01-01

We report the synthesis and characterization of a series of hierarchical porous zeolite single crystal materials with a range of porosities made available by carbon-templating using differently-sized carbon particles as templates for the additional non-micropore porosity. The materials were...

Integrated design of castings: effect of porosity on mechanical performance

International Nuclear Information System (INIS)

Hardin, R A; Beckermann, C

2012-01-01

Porosity can significantly reduce the strength and durability of castings in service. An integrated design approach has been developed where casting simulation is combined with mechanical performance simulations. Predictions of the porosity distribution from the casting process simulation are transferred to and used in stress and fatigue life simulations. Thus, the effect of casting quality on service performance can be evaluated. Results of a study are presented where the measured porosity distribution in cast steel specimens is transferred to an elasto-plastic finite-element stress analysis model. Methods are developed to locally reduce the mechanical properties according to the porosity present, without having to resolve individual pores. Plastic deformation is modeled using porous metal plasticity theory. The predictions are compared to tensile measurements performed on the specimens. The complex deformations and the reductions in the ductility of the specimens due to porosity are predicted well. The predicted stresses are transferred to a fatigue analysis code that takes the porosity distribution into account as well. The measured and predicted fatigue lives are also in good agreement. Finally, the results of a case study are presented that illustrate the utility of the present integrated approach in optimizing the design of a steel casting.

Porosity-dependent fractal nature of the porous silicon surface

Energy Technology Data Exchange (ETDEWEB)

Rahmani, N.; Dariani, R. S., E-mail: dariani@alzahra.ac.ir [Department of Physics, Alzahra University, Tehran, 1993893973 (Iran, Islamic Republic of)

2015-07-15

Porous silicon films with porosity ranging from 42% to 77% were fabricated by electrochemical anodization under different current density. We used atomic force microscopy and dynamic scaling theory for deriving the surface roughness profile and processing the topography of the porous silicon layers, respectively. We first compared the topography of bare silicon surface with porous silicon and then studied the effect of the porosity of porous silicon films on their scaling behavior by using their self-affinity nature. Our work demonstrated that silicon compared to the porous silicon films has the highest Hurst parameter, indicating that the formation of porous layer due to the anodization etching of silicon surface leads to an increase of its roughness. Fractal analysis revealed that the evolution of the nanocrystallites’ fractal dimension along with porosity. Also, we found that both interface width and Hurst parameter are affected by the increase of porosity.

The Application of Fractal and Multifractal Theory in Hydraulic-Flow-Unit Characterization and Permeability Estimation

Science.gov (United States)

Chen, X.; Yao, G.; Cai, J.

2017-12-01

Pore structure characteristics are important factors in influencing the fluid transport behavior of porous media, such as pore-throat ratio, pore connectivity and size distribution, moreover, wettability. To accurately characterize the diversity of pore structure among HFUs, five samples selected from different HFUs (porosities are approximately equal, however permeability varies widely) were chosen to conduct micro-computerized tomography test to acquire direct 3D images of pore geometries and to perform mercury injection experiments to obtain the pore volume-radii distribution. To characterize complex and high nonlinear pore structure of all samples, three classic fractal geometry models were applied. Results showed that each HFU has similar box-counting fractal dimension and generalized fractal dimension in the number-area model, but there are significant differences in multifractal spectrums. In the radius-volume model, there are three obvious linear segments, corresponding to three fractal dimension values, and the middle one is proved as the actual fractal dimension according to the maximum radius. In the number-radius model, the spherical-pore size distribution extracted by maximum ball algorithm exist a decrease in the number of small pores compared with the fractal power rate rather than the traditional linear law. Among the three models, only multifractal analysis can classify the HFUs accurately. Additionally, due to the tightness and low-permeability in reservoir rocks, connate water film existing in the inner surface of pore channels commonly forms bound water. The conventional model which is known as Yu-Cheng's model has been proved to be typically not applicable. Considering the effect of irreducible water saturation, an improved fractal permeability model was also deduced theoretically. The comparison results showed that the improved model can be applied to calculate permeability directly and accurately in such unconventional rocks.

Perovskite-related oxide materials for oxygen-permeable electrochemical membrans

OpenAIRE

Naumovich, E. N.; Yaremchenko, A. A.; Viskup, A. P.; Kharton, V. V.

2003-01-01

This brief review is focused on the studies of mixed ionic-electronic conductors on the basis of lanthanum gallate doped with transition metal cations in the В sublattice. The substitution of gallium with iron, cobalt or nickel results in greater electronic conductivity, simultaneously keeping high level of the oxy-gen ionic transport. In particular, La0 90Sr0 10Ga0 65Ni0 20Mg0 1503d perovskite exhib-its attractive oxygen permeability, which is quite similar to that of La2Ni04- and (...