Science.gov

Sample records for fluid-saturated porous rocks

  1. Fractional-calculus model for temperature and pressure waves in fluid-saturated porous rocks.

    PubMed

    Garra, Roberto

    2011-09-01

    We study a fractional time derivative generalization of a previous Natale-Salusti model about nonlinear temperature and pressure waves, propagating in fluid-saturated porous rocks. Their analytic solutions, i.e., solitary shock waves characterized by a sharp front, are here generalized, introducing a formalism that allows memory mechanisms. In realistic wave propagation in porous media we must take into account spatial or temporal variability of permeability, diffusivity, and other coefficients due to the system "history." Such a rock fracturing or fine particulate migration could affect the rock and its pores. We therefore take into account these phenomena by introducing a fractional time derivative to simulate a memory-conserving formalism. We also discuss this generalized model in relation to the theory of dynamic permeability and tortuosity in fluid-saturated porous media. In such a realistic model we obtain exact solutions of Burgers' equation with time fractional derivatives in the inviscid case.

  2. Numerical Analysis of Velocity Dispersion in Multi-Phase Fluid-Saturated Porous Rocks

    NASA Astrophysics Data System (ADS)

    Chen, Xuehua; Zhong, Wenli; Gao, Gang; Zou, Wen; He, Zhenhua

    2016-12-01

    Seismic waves are subject to velocity dispersion when they propagate in fluid-saturated porous media. In this work, we explore the velocity dispersion behavior of P- and SV-waves in multi-phase fluid-saturated porous reservoirs while taking into account the effects of multi-phase pore fluids on the effective viscosities that control the wave-induced fluid flow. The effective viscosities associated with the hydrocarbon saturation of a synthetic sandstone reservoir saturated with different pore fluid mixtures are calculated using the Refutas model. We then analyze the frequency-dependent velocity, dispersion variation rate and characteristic frequency for different fluid saturation cases by employing Chapman's dynamic equivalent-medium theory. The results demonstrate that the hydrocarbon proportions and types in multi-phase mixed pore fluids significantly affect the magnitude and characteristic frequencies of velocity dispersion features for both the P- and S-waves. The dispersion anomalies of SV-waves are in general larger than those of the P-waves. This indicates that the velocity dispersion anomalies of SV-waves are equally sensitive to fluid saturation as the P-waves and should not be neglected. The velocities at lower frequencies (e.g., 10 and 100 Hz) within the seismic frequency range show a more remarkable decrease with increasing hydrocarbon proportion than those at higher frequency (1000 Hz). The numerical examples help to improve the understanding of the frequency-dependent AVO inversion from seismic reflection data.

  3. Numerical Analysis of Velocity Dispersion in Multi-Phase Fluid-Saturated Porous Rocks

    NASA Astrophysics Data System (ADS)

    Chen, Xuehua; Zhong, Wenli; Gao, Gang; Zou, Wen; He, Zhenhua

    2017-03-01

    Seismic waves are subject to velocity dispersion when they propagate in fluid-saturated porous media. In this work, we explore the velocity dispersion behavior of P- and SV-waves in multi-phase fluid-saturated porous reservoirs while taking into account the effects of multi-phase pore fluids on the effective viscosities that control the wave-induced fluid flow. The effective viscosities associated with the hydrocarbon saturation of a synthetic sandstone reservoir saturated with different pore fluid mixtures are calculated using the Refutas model. We then analyze the frequency-dependent velocity, dispersion variation rate and characteristic frequency for different fluid saturation cases by employing Chapman's dynamic equivalent-medium theory. The results demonstrate that the hydrocarbon proportions and types in multi-phase mixed pore fluids significantly affect the magnitude and characteristic frequencies of velocity dispersion features for both the P- and S-waves. The dispersion anomalies of SV-waves are in general larger than those of the P-waves. This indicates that the velocity dispersion anomalies of SV-waves are equally sensitive to fluid saturation as the P-waves and should not be neglected. The velocities at lower frequencies (e.g., 10 and 100 Hz) within the seismic frequency range show a more remarkable decrease with increasing hydrocarbon proportion than those at higher frequency (1000 Hz). The numerical examples help to improve the understanding of the frequency-dependent AVO inversion from seismic reflection data.

  4. Do seismic waves and fluid flow sense the same permeability in fluid-saturated porous rocks?

    NASA Astrophysics Data System (ADS)

    Rubino, J. G.; Monachesi, L. B.; Guarracino, L.; Müller, T. M.; Holliger, K.

    2012-04-01

    Wave-induced flow due to the the presence of mesoscopic heterogeneities, that is, heterogeneities that are larger than the pore size but smaller than the prevailing seismic wavelengths, represents an important seismic attenuation mechanism in fluid-saturated porous rocks. In this context, it is known that in the presence of strong permeability fluctuations, there is a discrepancy between the effective flow permeability and the effective seismic permeability, that is, the effective permeability controlling seismic attenuation due to wave-induced fluid flow. While this subject has been analyzed for the case of random 1D media, the corresponding 2D and 3D cases remain unexplored, mainly due to the fact that, as opposed to the 1D case, there is no simple expression for the effective flow permeability. In this work we seek to address this problem through the numerical analysis of 2D rock samples having strong permeability fluctuations. In order to do so, we employ a numerical oscillatory compressibility test to determine attenuation and velocity dispersion due to wave-induced fluid flow in these kinds of media and compare the responses with those obtained by replacing the heterogeneous permeability field by homogeneous fields, with permeability values given by the average permeability as well as the effective flow permeability of the sample. The latter is estimated in a separate upscaling procedure by solving the steady-state flow equation in the rock sample under study. Numerical experiments let us verify that the attenuation levels are less significant and the attenuation peak gets broader in the presence of such strong permeability fluctuations. Moreover, we observe that for very low frequencies the effective seismic permeability is similar to the effective flow permeability, while for very high frequencies it approaches the arithmetic average of the permeability field.

  5. (Investigation of ultrasonic wave interactions with fluid-saturated porous rocks)

    SciTech Connect

    Adler, L.

    1992-01-01

    During the last two years we have continued our investigation of ultrasonic wave propagation in fluid-filled porous materials. First, we studied the feasibility of using different surface modes to characterize both synthetic and natural rocks. We introduced a novel experimental technique based on the direct generation of surface waves by edge excitation. We used two low-frequency (100--500 kHz) shear transducers in pitch-catch mode to launch and receive the ultrasonic surface wave. The contact transducers were coupled to the opposite edges of the porous specimens with normal polarization relative to the surface. The same technique was successfully used to generate Rayleigh-type surface modes on the free surface of both dry and water-saturated specimens, as well as Stoneley-type interface modes on the fluid-loaded surfaces of immersed samples. Our main achievement in this area is the realization that, due to surface tension, practically closed-pore boundary conditions can prevail on the free surface of a water-saturated rock for completely open pores. As a result, the velocity of the true surface mode might be much lower than the Rayleigh velocity of the dry skeleton.

  6. [Investigation of ultrasonic wave interactions with fluid-saturated porous rocks]. [Annual report

    SciTech Connect

    Adler, L.

    1992-07-01

    During the last two years we have continued our investigation of ultrasonic wave propagation in fluid-filled porous materials. First, we studied the feasibility of using different surface modes to characterize both synthetic and natural rocks. We introduced a novel experimental technique based on the direct generation of surface waves by edge excitation. We used two low-frequency (100--500 kHz) shear transducers in pitch-catch mode to launch and receive the ultrasonic surface wave. The contact transducers were coupled to the opposite edges of the porous specimens with normal polarization relative to the surface. The same technique was successfully used to generate Rayleigh-type surface modes on the free surface of both dry and water-saturated specimens, as well as Stoneley-type interface modes on the fluid-loaded surfaces of immersed samples. Our main achievement in this area is the realization that, due to surface tension, practically closed-pore boundary conditions can prevail on the free surface of a water-saturated rock for completely open pores. As a result, the velocity of the true surface mode might be much lower than the Rayleigh velocity of the dry skeleton.

  7. Standing Torsional Waves in Fluid-Saturated Porous Circular Cylinder

    NASA Astrophysics Data System (ADS)

    Solorza, S.; Sahay, P. N.

    2002-12-01

    For dynamic measurement of elastic constants of a porous material saturated with viscous fluid when resonance-bar technique is applied, one also observes attenuation of the wave field. The current practice is to interpret it in terms of solid-viscosity by assuming a viscoelastic rheology for porous material. The likely mechanisms of attenuation in a fluid saturated porous material are: 1) motion of the fluid with respect to the solid frame and 2) viscous loss within the pore fluid. Therefore, it is appropriate to assume a poroelastic rheology and link the observed attenuation value to fluid properties and permeability. In the framework of poroelastic theory, the explicit formula linking attenuation to the properties of solid and fluid constituents and permeability are not worked out yet. In order to established such a link one has to workout solutions of appropriate boundary value problems in such a framework. Here, we have carried out the solution of boundary value problem associated with torsional oscillation of a finite poroelastic circular cylinder, casted in the framework of volume-averaged theory of poroelasticity. Analysing this solution by a perturbative approach we are able to develop explicit expressions for resonance frequency and attenuation for this mode of vibration. It shows how the attenuation is controlled by the permeability and the fluid properties, and how the resonance frequency drops over its value for the dry porous frame due to the effect of the fluid-mass.

  8. Wave propagation in fluid-saturated porous media

    NASA Astrophysics Data System (ADS)

    Ren, Jiaxiang

    The wave propagation in fluid-saturated porous media is studied by solving the Biot equations, the governing equations for the motion of the porous medium. Methods are devised to solve the Biot equations for different problems and medium models. The problem of the reflection and transmission at an interface is solved by using the eigen-analysis of the Biot equations. The displacement-stress vectors in the media on both sides of the interface are represented by corresponding upgoing and downgoing wave vectors which are then linked by the boundary conditions on the interface. The reflection and transmission coefficients are extracted from the proportionalities between the upgoing and downgoing waves. For an incident fast wave or shear wave, the reflection and transmission coefficients for the reflected and transmitted slow waves are very sensitive to frequency and interface permeability (kappasb{I}); while those for the reflected and transmitted fast waves and shear waves are not, except when incident angles are close to and greater than critical angles. For sandstones, the amplitudes of the reflected and transmitted slow waves could be several percent of the amplitude of the incident fast wave or shear wave. Higher interface permeabilities favor the generation of the slow wave. The slow waves generated at an open interface (kappasb{I}->infty) and a sealed interface (kappasb{I}=0) could be one-order different in amplitude. The reflection and transmission at an interface have been extended to the model composed of multi-layers of porous media. An algorithm based on the compact finite-difference method is developed for 2-D seismic modeling. The compact finite-difference method is used to estimate the spatial derivatives in the Biot equations, with a 6sp{th}-order accuracy. It needs fewer grid intervals to represent a mono-wavelength function than the traditional 2sp{nd}-order central-difference method. Therefore, the algorithm based on the compact finite

  9. The use of agarose gels for quantitative determination of fluid saturations in porous media.

    PubMed

    Chang, C T; Mandava, S; Watson, A T; Sarkar, S; Edwards, C M

    1993-01-01

    The use of agarose gel reference standards for quantifying petrophysical properties in porous media is described. The specific interest is to determine the values of fluid saturations and porosity in oil bearing rocks; the MRI methodology for estimating these properties is discussed. It is shown that the relaxation times of the gel reference standard and the relaxation times of the fluid contained in the porous media affect the estimation process. The determination of porosity and fluid saturations can be greatly simplified if the relaxation times of the reference standard and the relaxation times of the fluid are closely matched. Gel concentration of paramagnetic impurities in the form of copper ions is used to control the longitudinal relaxation properties. The relaxation properties of agarose gels, as a function of agarose and paramagnetic impurity concentrations, have been measured at 2.0 T. The data are well fitted by a simple polynomial in agarose concentration and paramagnetic impurity concentration. Finally, a one-dimensional imaging example of use of agarose gels as reference phantoms is discussed.

  10. Double-diffusive natural convection in a fluid saturated porous cavity with a freely convecting wall

    SciTech Connect

    Nithiarasu, P.; Sundararajan, T.; Seetharamu, K.N.

    1997-12-01

    Double-diffusive natural convection in fluid saturated porous medium has been investigated using a generalized porous medium model. One of the vertical walls of the porous cavity considered is subjected to convective heat and mass transfer conditions. The results show that the flow, heat and mass transfer become sensitive to applied mass transfer coefficient in both the Darcy and non-Darcy flow regimes. It is also observed that the Sherwood number approaches a constant value as the solutal Biot number increases. Double-diffusive natural convection in fluid saturated porous medium is encountered in applications such as food processing, contaminant transport in ground water, and others.

  11. Seismic attenuation: Laboratory measurements in fluid saturated rocks

    NASA Astrophysics Data System (ADS)

    Subramaniyan, Shankar; Madonna, Claudio; Tisato, Nicola; Saenger, Erik; Quintal, Beatriz

    2014-05-01

    Seismic wave attenuation could be used as an indicator of reservoir fluids due to its dependence on rock and fluid properties. Over the past 30 years, many laboratory methodologies to study attenuation in rocks have been employed, such as ultrasonic (MHz), resonant bar (kHz) and forced oscillation methods in the low frequency range (0.01-100Hz) (Tisato & Madonna 2012; Madonna & Tisato 2013). Forced oscillation methods have gained prominence over time as the frequency range of measurements correspond to that of field seismic data acquired for oil/gas exploration. These experiments measure attenuation as the phase shift between the applied stress (sinusoidal) and measured strain. Since the magnitudes of measured phase shifts are quite low (Q-1 ~0.01-0.1) and the amplitudes of strain applied to the rock samples are of the order ~10-6 (i.e., similar orders of magnitude to seismic waves), it is challenging. A comparison of such forced oscillation setups will be presented to provide an overview of the various possibilities of design and implementation for future setups. In general, there is a lack of laboratory data and most of the published data are for sandstones. Currently, attenuation measurements are being carried out on carbonate and sandstone samples. We employ the Seismic Wave Attenuation Module (SWAM, Madonna & Tisato 2013) to measure seismic attenuation in these samples for different saturation degrees (90% and 100% water) and under three different confining pressures (5, 10 and 15MPa). Preliminary results from these investigations will be discussed. REFERENCES Madonna, C. & Tisato, N. 2013: A new seismic wave attenuation module to experimentally measure low-frequency attenuation in extensional mode. Geophysical Prospecting, doi: 10.1111/1365-2478.12015. Tisato, N. & Madonna, C. 2012: Attenuation at low seismic frequencies in partially saturated rocks: Measurements and description of a new apparatus. Journal of Applied Geophysics, 86, 44-53.

  12. Study of Surface Wave Propagation in Fluid-Saturated Porous Solids.

    NASA Astrophysics Data System (ADS)

    Azcuaga, Valery Francisco Godinez

    1995-01-01

    This study addresses the surface wave propagation phenomena on fluid-saturated porous solids. The analytical method for calculation of surface wave velocities (Feng and Johnson, JASA, 74, 906, 1983) is extended to the case of a porous solid saturated with a wetting fluid in contact with a non-wetting fluid, in order to study a material combination suitable for experimental investigation. The analytical method is further extended to the case of a non-wetting fluid/wetting fluid-saturated porous solid interface with an arbitrary finite surface stiffness. These extensions of the analytical method allows to theoretically study surface wave propagation phenomena during the saturation process. A modification to the 2-D space-time reflection Green's function (Feng and Johnson, JASA, 74, 915, 1983) is introduced in order to simulate the behavior of surface wave signals detected during the experimental investigation of surface wave propagation on fluid-saturated porous solids (Nagy, Appl. Phys. Lett., 60, 2735, 1992). This modification, together with the introduction of an excess attenuation for the Rayleigh surface mode, makes it possible to explain the apparent velocity changes observed on the surface wave signals during saturation. Experimental results concerning the propagation of surface waves on an alcohol-saturated porous glass are presented. These experiments were performed at frequencies of 500 and 800 kHz and show the simultaneous propagation of the two surface modes predicted by the extended analytical method. Finally an analysis of the displacements associated with the different surface modes is presented. This analysis reveals that it is possible to favor the generation of the Rayleigh surface mode or of the slow surface mode, simply by changing the type of transducer used in the generation of surface waves. Calculations show that a shear transducer couples more energy into the Rayleigh mode, whereas a longitudinal transducer couples more energy into the slow

  13. Synchrotron radiation measurement of multiphase fluid saturations in porous media: Experimental technique and error analysis

    NASA Astrophysics Data System (ADS)

    Tuck, David M.; Bierck, Barnes R.; Jaffé, Peter R.

    1998-06-01

    Multiphase flow in porous media is an important research topic. In situ, nondestructive experimental methods for studying multiphase flow are important for improving our understanding and the theory. Rapid changes in fluid saturation, characteristic of immiscible displacement, are difficult to measure accurately using gamma rays due to practical restrictions on source strength. Our objective is to describe a synchrotron radiation technique for rapid, nondestructive saturation measurements of multiple fluids in porous media, and to present a precision and accuracy analysis of the technique. Synchrotron radiation provides a high intensity, inherently collimated photon beam of tunable energy which can yield accurate measurements of fluid saturation in just one second. Measurements were obtained with precision of ±0.01 or better for tetrachloroethylene (PCE) in a 2.5 cm thick glass-bead porous medium using a counting time of 1 s. The normal distribution was shown to provide acceptable confidence limits for PCE saturation changes. Sources of error include heat load on the monochromator, periodic movement of the source beam, and errors in stepping-motor positioning system. Hypodermic needles pushed into the medium to inject PCE changed porosity in a region approximately ±1 mm of the injection point. Improved mass balance between the known and measured PCE injection volumes was obtained when appropriate corrections were applied to calibration values near the injection point.

  14. Phase field modeling of crack propagations in fluid-saturated porous media with anisotropic surface energy

    NASA Astrophysics Data System (ADS)

    Na, S.; Sun, W.; Yoon, H.; Choo, J.

    2016-12-01

    Directional mechanical properties of layered geomaterials such as shale are important on evaluating the onset and growth of fracture for engineering applications such as hydraulic fracturing, geologic carbon storage, and geothermal recovery. In this study, a continuum phase field modeling is conducted to demonstrate the initiation and pattern of cracks in fluid-saturated porous media. The discontinuity of sharp cracks is formulated using diffusive crack phase field modeling and the anisotropic surface energy is incorporated to account for the directional fracture toughness. In particular, the orientation of bedding in geomaterials with respect to the loading direction is represented by the directional critical energy release rate. Interactions between solid skeleton and fluid are also included to analyze the mechanical behavior of fluid-saturated geologic materials through the coupled hydro-mechanical model. Based on the linear elastic phase field modeling, we also addressed how the plasticity in crack phase field influences the crack patterns by adopting the elasto-plastic model with Drucker-Prager yield criterion. Numerical examples exhibit the features of anisotropic surface energy, the interactions between solid and fluid and the effects of plasticity on crack propagations.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.

  15. Phenomenological model of propagation of the elastic waves in a fluid-saturated porous solid with nonzero boundary slip velocity.

    PubMed

    Tsiklauri, David

    2002-09-01

    It is known that a boundary slip velocity starts to play an important role when the length scale over which the fluid velocity changes approaches the slip length, i.e., when the fluid is highly confined, for example, fluid flow through porous rock or blood vessel capillaries. Zhu and Granick [Phys. Rev. Lett. 87, 096105 (2001)] have recently experimentally established the existence of a boundary slip in a Newtonian liquid. They reported typical values of the slip length of the order of few micrometers. In this light, the effect of introduction of the boundary slip into the theory of propagation of elastic waves in a fluid-saturated porous medium formulated by Biot [J. Acoust. Soc. Am. 28, 179-191 (1956)] is investigated. Namely, the effect of introduction of boundary slip upon the function F(kappa) that measures the deviation from Poiseuille flow friction as a function of frequency parameter kappa is studied. By postulating phenomenological dependence of the slip velocity upon frequency, notable deviations in the domain of intermediate frequencies in the behavior of F(kappa) are introduced with the incorporation of the boundary slip into the model. It is known that F(kappa) crucially enters Biot's equations, which describe dynamics of fluid-saturated porous solid. Thus, consequences of the nonzero boundary slip by calculating the phase velocities and attenuation coefficients of both rotational and dilatational waves with the variation of frequency are investigated. The new model should allow one to fit the experimental seismic data in circumstances when Biot's theory fails, as the introduction of phenomenological dependence of the slip velocity upon frequency, which is based on robust physical arguments, adds an additional degree of freedom to the model. In fact, it predicts higher than the Biot's theory values of attenuation coefficients of the both rotational and dilatational waves in the intermediate frequency domain, which is in qualitative agreement with the

  16. Liquid accumulation in vibrating vocal fold tissue: a simplified model based on a fluid-saturated porous solid theory.

    PubMed

    Tao, Chao; Jiang, Jack J; Czerwonka, Lukasz

    2010-05-01

    The human vocal fold is treated as a continuous, transversally isotropic, porous solid saturated with liquid. A set of mathematical equations, based on the theory of fluid-saturated porous solids, is developed to formulate the vibration of the vocal fold tissue. As the fluid-saturated porous tissue model degenerates to the continuous elastic tissue model when the relative movement of liquid in the porous tissue is ignored, it can be considered a more general description of vocal fold tissue than the continuous, elastic model. Using the fluid-saturated porous tissue model, the vibration of a bunch of one-dimensional fibers in the vocal fold is analytically solved based on the small-amplitude assumption. It is found that the vibration of the tissue will lead to the accumulation of excess liquid in the midmembranous vocal fold. The degree of liquid accumulation is positively proportional to the vibratory amplitude and frequency. The correspondence between the liquid distribution predicted by the porous tissue theory and the location of vocal nodules observed in clinical practice, provides theoretical evidence for the liquid accumulation hypothesis of vocal nodule formation (Jiang, Ph.D., dissertation, 1991, University of Iowa). (c) 2010 The Voice Foundation. Published by Mosby, Inc. All rights reserved.

  17. Supercritical Hadley circulation within a layer of fluid saturated porous medium: Bifurcation to traveling wave

    SciTech Connect

    Manole, D.M.; Lage, J.L.; Antohe, B.V.

    1995-12-31

    Hadley circulation induced by horizontal and vertical temperature gradients imposed on a fluid saturated porous medium layer is simulated numerically. The flow is assumed to be longitudinal, that is the secondary flow is composed of cells with axes transverse to the direction of the Hadley circulation. Critical (bifurcation) states predicted theoretically via linear stability analysis are verified by the numerical results giving confidence on the accuracy of the method. Several values of horizontal Rayleigh number, Ra{sub h}, and vertical Rayleigh number, Ra{sub v}, are studied. Results indicate that beyond a threshold horizontal Rayleigh number value the flow and temperature fields evolve from subcritical Hadley circulation to a supercritical time periodic flow. The secondary flow emerges in the form of a traveling wave aligned with the main (Hadley) flow direction. This traveling wave is characterized, at supercritical low vertical Rayleigh numbers, by the continuous drifting of two horizontal layers of flow cells that move in opposite directions. As the vertical Rayleigh number increases, the traveling wave becomes characterized by a unique layer of cells drifting in the direction opposite to the applied horizontal temperature gradient. Numerical animation unravels the main features of the transport process. This simplified model is of fundamental and practical importance, for instance, to the study of geothermal activities, underground transport of pollutants, paper processing, crystal growth, building insulation, and gas reservoirs.

  18. Diffusion of high-frequency energy in fluid-saturated porous media

    NASA Astrophysics Data System (ADS)

    Savin, Eric

    2004-05-01

    The modern mathematical theory of microlocal analysis shows that the energy associated with the high-frequency solutions of hyperbolic partial differential equations (such as the wave or the Navier equations) satisfy Liouville-type transport equations, or radiative transfer equations for randomly heterogeneous media. For long propagation times the latter can be approached by diffusion equations. Some classical results of the structural acoustics literature about the heat conduction analogy and the statistical energy analysis of structural dynamics at higher frequencies are recovered in this process. The purpose of this communication is to focus on such a diffusive regime for isotropic, fluid-saturated porous media. More specifically, we have derived the diffusion parameters (transport mean-free path and diffusion constant) for such media. Our model considers Biot's equations of poroelasticity, where thermal and viscous effects are modelized by dynamic tortuosity and compressibility with singular memory kernels. The macroscopic bulk modulus and density of the dry solid phase are assumed to be homogeneous random processes, while tortuosity and porosity remain constant.

  19. Acoustic emission in a fluid saturated heterogeneous porous layer with application to hydraulic fracture

    SciTech Connect

    Nelson, J.T. . Dept. of Mechanical Engineering Lawrence Berkeley Lab., CA )

    1988-11-01

    A theoretical model for acoustic emission in a vertically heterogeneous porous layer bounded by semi-infinite solid regions is developed using linearized equations of motion for a fluid/solid mixture and a reflectivity method. Green's functions are derived for both point loads and moments. Numerically integrated propagators represent solutions for intermediate heterogeneous layers in the porous region. These are substituted into a global matrix for solution by Gaussian elimination and back-substitution. Fluid partial stress and seismic responses to dislocations associated with fracturing of a layer of rock with a hydraulically conductive fracture network are computed with the model. A constitutive model is developed for representing the fractured rock layer as a porous material, using commonly accepted relationships for moduli. Derivations of density, tortuosity, and sinuosity are provided. The main results of the model application are the prediction of a substantial fluid partial stress response related to a second mode wave for the porous material. The response is observable for relatively large distances, on the order of several tens of meters. The visco-dynamic transition frequency associated with parabolic versus planar fluid velocity distributions across micro-crack apertures is in the low audio or seismic range, in contrast to materials with small pore size, such as porous rocks, for which the transition frequency is ultrasonic. Seismic responses are predicted for receiver locations both in the layer and in the outlying solid regions. In the porous region, the seismic response includes both shear and dilatational wave arrivals and a second-mode arrival. The second-mode arrival is not observable outside of the layer because of its low velocity relative to the dilatational and shear wave propagation velocities of the solid region.

  20. Effects of mechanical dispersion on the morphological evolution of a chemical dissolution front in a fluid-saturated porous medium

    NASA Astrophysics Data System (ADS)

    Chen, Jui-Sheng; Liu, Chen-Wuing; Lai, Geng-Xin; Ni, Chuen-Fa

    2009-06-01

    SummaryThe dissolution-induced finger or wormhole patterns in porous medium or fracture rock play a crucial role in a variety of scientific, industrial, and engineering practices. Although previous studies have extensively presented a number of numerical models which couples a system of nonlinear governing equations of porosity change due to mineral dissolution, the conservations of groundwater flow and transport of chemical species to investigate the morphological pattern of a chemical dissolution front within a fluid-saturated porous medium, whereas the mechanical dispersion effect has generally been neglected in the model development. This study addresses the effects of mechanical dispersion on the morphological evolution of a chemical dissolution front for a variety of cases. Mechanical dispersion processes is incorporated with the coupled nonlinear governing equation system so as to rebuild a newly numerical model. The results of numerical simulations demonstrate that mechanical dispersion has pronounced impacts on the morphological pattern of the chemical dissolution front. For single local non-uniformity case, mechanical dispersion reduces the finger length of an unstable single-fingering front or retains the shape of a stable planar front while speeding up the front advancement. In the case of two local non-uniformities, adding mechanical dispersion with different flow conditions can yield one of the following results: (1) the shape of the stable planar front is maintained but its advancement is accelerated; (2) the shape of the unstable single-fingering front is maintained but its length is reduced; (3) the unstable double-fingering front is merged into an unstable single-fingering front; and (4) the shape of the unstable double-fingering front is preserved but its fingering length is reduced. A comparison between the behavior diagrams of dissolution front morphology (with and without considering mechanical dispersion) shows that the double-fingering front

  1. Modeling of wave processes in blocky media with porous and fluid-saturated interlayers

    NASA Astrophysics Data System (ADS)

    Sadovskii, Vladimir M.; Sadovskaya, Oxana V.; Lukyanov, Alexander A.

    2017-09-01

    The wave processes in blocky media are analyzed by applying different mathematical models, wherein the elastic blocks interact with each other via pliant interlayers with the complex mechanical properties. Four versions of constitutive equations are considered. In the first version, an elastic interaction between the blocks is simulated within the framework of linear elasticity theory, and the model of elastic-plastic interlayers is constructed to take into account the appearance of irreversible deformation of interlayers at short time intervals. In the second one, the effects of viscoelastic shear in the interblock interlayers are taken into the consideration using the Poynting-Thomson rheological scheme. In the third option, the model of an elastic porous material is used in the interlayers, where the pores collapse if an abrupt compressive stress is applied. In the fourth case, the model of a fluid-saturated material with open pores is examined based on Biot's equations. The collapse of pores is modeled by the generalized rheological approach, wherein the mechanical properties of a material are simulated using four rheological elements. Three of them are the traditional elastic, viscous and plastic elements, the fourth element is the so-called rigid contact, which is used to describe the behavior of materials with the different resistance to tension and compression. It was shown that the thermodynamically consistent model is provided, which means that the energy balance equation is fulfilled for an entire blocky structure, where the kinetic and potential energy of the system is the sum of the kinetic and potential energies of the blocks and interlayers. Under numerical implementation of the interlayers models, the dissipationless finite difference Ivanov's method was used. The splitting method by spatial variables in the combination with the Godunov gap decay scheme was applied in the blocks. As a result, robust and stable computational algorithms are built and

  2. A rocking multianvil: elimination of chemical segregation in fluid-saturated high-pressure experiments

    NASA Astrophysics Data System (ADS)

    Schmidt, Max W.; Ulmer, Peter

    2004-04-01

    Fluid saturated high-pressure experiments often result in strongly zoned experimental charges, this hinders experimentation in chemically homogeneous systems which in turn has serious consequences on equilibration, reaction progress, and (apparent) phase stabilities. In order to overcome these problems, a 600-ton press accommodating either a multianvil or end-loaded piston cylinder module has been mounted in such a way that it can be turned by 180°, thus inverting its position in the gravity field. During turning, hydraulic pressure, heating power, and cooling water remain connected allowing fully controlled pressures and temperatures during experiments. A series of experiments at 13 GPa, 950°C, on a serpentine bulk composition in the MgO-SiO 2-H 2O system demonstrates that continuous turning at a rate of 2 turns/min results in a nearly homogeneous charge composed of phase E + enstatite. The same experiment at static conditions resulted in four mineral zones: quench phase E, enstatite, enstatite + phase E, and phase E + phase A. Phase A disappears in experiments at a turning rate ≥1 turn/min. A static 15-min experiment shows that zonation already forms within this short time span. Placing two short capsules within a single static experiment reveals that the fluid migrates to the hot spot in each capsule and is not gravitationally driven toward the top. The zonation pattern follows isotherms within the capsule, and the degree of zonation increases with temperature gradient (measured as 10 °C within a capsule) and run time. Our preferred interpretation is that Soret diffusion causes a density-stratified fluid within the capsule that does not convect in a static experiment and results in temperature dependant chemical zonation. The aggravation of zonation and appearance of additional phases with run time can be explained with a dissolution-reprecipitation process where the cold spot of the capsule is relatively MgO enriched and the hot spot relatively SiO 2 and H

  3. The onset of double diffusive convection in a viscoelastic fluid-saturated porous layer with non-equilibrium model.

    PubMed

    Yang, Zhixin; Wang, Shaowei; Zhao, Moli; Li, Shucai; Zhang, Qiangyong

    2013-01-01

    The onset of double diffusive convection in a viscoelastic fluid-saturated porous layer is studied when the fluid and solid phase are not in local thermal equilibrium. The modified Darcy model is used for the momentum equation and a two-field model is used for energy equation each representing the fluid and solid phases separately. The effect of thermal non-equilibrium on the onset of double diffusive convection is discussed. The critical Rayleigh number and the corresponding wave number for the exchange of stability and over-stability are obtained, and the onset criterion for stationary and oscillatory convection is derived analytically and discussed numerically.

  4. Dynamic bulk and shear moduli due to grain-scale local fluid flow in fluid-saturated cracked poroelastic rocks: Theoretical model

    NASA Astrophysics Data System (ADS)

    Song, Yongjia; Hu, Hengshan; Rudnicki, John W.

    2016-07-01

    Grain-scale local fluid flow is an important loss mechanism for attenuating waves in cracked fluid-saturated poroelastic rocks. In this study, a dynamic elastic modulus model is developed to quantify local flow effect on wave attenuation and velocity dispersion in porous isotropic rocks. The Eshelby transform technique, inclusion-based effective medium model (the Mori-Tanaka scheme), fluid dynamics and mass conservation principle are combined to analyze pore-fluid pressure relaxation and its influences on overall elastic properties. The derivation gives fully analytic, frequency-dependent effective bulk and shear moduli of a fluid-saturated porous rock. It is shown that the derived bulk and shear moduli rigorously satisfy the Biot-Gassmann relationship of poroelasticity in the low-frequency limit, while they are consistent with isolated-pore effective medium theory in the high-frequency limit. In particular, a simplified model is proposed to quantify the squirt-flow dispersion for frequencies lower than stiff-pore relaxation frequency. The main advantage of the proposed model over previous models is its ability to predict the dispersion due to squirt flow between pores and cracks with distributed aspect ratio instead of flow in a simply conceptual double-porosity structure. Independent input parameters include pore aspect ratio distribution, fluid bulk modulus and viscosity, and bulk and shear moduli of the solid grain. Physical assumptions made in this model include (1) pores are inter-connected and (2) crack thickness is smaller than the viscous skin depth. This study is restricted to linear elastic, well-consolidated granular rocks.

  5. Influence of viscous dissipation and thermophoresis on Darcy-Forchheimer mixed convection in a fluid saturated porous media.

    PubMed

    Seddeek, M A

    2006-01-01

    Mixed convection flow, heat, and mass transfer about an isothermal vertical flat plate embedded in a fluid-saturated porous medium and the effects of viscous dissipation and thermophoresis in both aiding and opposing flows are analyzed. The similarity solution is used to transform the problem under consideration into a boundary value problem of coupled ordinary differential equations, which are solved numerically by using the shooting method. Numerical computations are carried out for the non-dimensional physical parameter. The results are analyzed for the effect of different physical parameters such as thermophoretic, mixed convection, inertia parameter, buoyancy ratio, and Schmid number on the flow, heat, and mass transfer characteristics. Two cases are considered, one corresponding to the presence of viscous dissipation and the other to the absence of it.

  6. Stability Analysis and Internal Heating Effect on Oscillatory Convection in a Viscoelastic Fluid Saturated Porous Medium Under Gravity Modulation

    NASA Astrophysics Data System (ADS)

    Bhadauria, B. S.; Singh, M. K.; Singh, A.; Singh, B. K.; Kiran, P.

    2016-12-01

    In this paper, we investigate the combined effect of internal heating and time periodic gravity modulation in a viscoelastic fluid saturated porous medium by reducing the problem into a complex non-autonomous Ginzgburg-Landau equation. Weak nonlinear stability analysis has been performed by using power series expansion in terms of the amplitude of gravity modulation, which is assumed to be small. The Nusselt number is obtained in terms of the amplitude for oscillatory mode of convection. The influence of viscoelastic parameters on heat transfer has been discussed. Gravity modulation is found to have a destabilizing effect at low frequencies and a stabilizing effect at high frequencies. Finally, it is found that overstability advances the onset of convection, more with internal heating. The conditions for which the complex Ginzgburg-Landau equation undergoes Hopf bifurcation and the amplitude equation undergoes supercritical pitchfork bifurcation are studied.

  7. Rayleigh-Benard convection subject to time dependent wall temperature/gravity in a fluid-saturated anisotropic porous medium

    NASA Astrophysics Data System (ADS)

    Malashetty, M. S.; Basavaraja, D.

    The effect of time-periodic temperature/gravity modulation at the onset of convection in a Boussinesq fluid-saturated anisotropic porous medium is investigated by making a linear stability analysis. Brinkman flow model with effective viscosity larger than the viscosity of the fluid is considered to give a more general theoretical result. The perturbation method is applied for computing the critical Rayleigh and wave numbers for small amplitude temperature/gravity modulation. The shift in the critical Rayleigh number is calculated as a function of frequency of the modulation, viscosity ratio, anisotropy parameter and porous parameter. We have shown that it is possible to advance or delay the onset of convection by time-periodic modulation of the wall temperature and to advance convection by gravity modulation. It is also shown that the small anisotropy parameter has a strong influence on the stability of the system. The effect of viscosity ratio, anisotropy parameter, the porous parameter and the Prandtl number is discussed.

  8. Thermal instability of a fluid-saturated porous medium bounded by thin fluid layers

    SciTech Connect

    Pillatsis, G.; Taslim, M.E.; Narusawa, U. )

    1987-08-01

    A linear stability analysis is performed for a horizontal Darcy porous layer of depth 2d{sub m} sandwiched between two fluid layers of depth d (each) with the top and bottom boundaries being dynamically free and kept at fixed temperatures. The Beavers-Joseph condition is employed as one of the interfacial boundary conditions between the fluid and the porous layer. The critical Rayleigh number and the horizontal wave number for the onset of convective motion depend on the following four dimensional parameters: {cflx d} (= d{sub m}/d, the depth ratio), {delta} (= {radical}K/d{sub m} with K being the permeability of the porous medium) {alpha} (the proportionality constant in the Beavers-Joseph condition), and k/k{sub m} (the thermal conductivity ratio). In order to analyze the effect of these parameters on the stability condition, a set of numerical solutions is obtained in terms of a convergent series for the respective layers, for the case in which the thickness of the porous layer is much greater than that of the fluid layer. A comparison of this study with the previously obtained exact solution for the case of constant heat flux boundaries is made to illustrate quantitative effects of the interfacial and the top/bottom boundaries on the thermal instability of a combined system of porous and fluid layers.

  9. An agent-based method for simulating porous fluid-saturated structures with indistinguishable components

    NASA Astrophysics Data System (ADS)

    Kashani, Jamal; Pettet, Graeme John; Gu, YuanTong; Zhang, Lihai; Oloyede, Adekunle

    2017-10-01

    Single-phase porous materials contain multiple components that intermingle up to the ultramicroscopic level. Although the structures of the porous materials have been simulated with agent-based methods, the results of the available methods continue to provide patterns of distinguishable solid and fluid agents which do not represent materials with indistinguishable phases. This paper introduces a new agent (hybrid agent) and category of rules (intra-agent rule) that can be used to create emergent structures that would more accurately represent single-phase structures and materials. The novel hybrid agent carries the characteristics of system's elements and it is capable of changing within itself, while also responding to its neighbours as they also change. As an example, the hybrid agent under one-dimensional cellular automata formalism in a two-dimensional domain is used to generate patterns that demonstrate the striking morphological and characteristic similarities with the porous saturated single-phase structures where each agent of the ;structure; carries semi-permeability property and consists of both fluid and solid in space and at all times. We conclude that the ability of the hybrid agent to change locally provides an enhanced protocol to simulate complex porous structures such as biological tissues which could facilitate models for agent-based techniques and numerical methods.

  10. Turbulent flow over a channel with fluid-saturated porous bed

    USDA-ARS?s Scientific Manuscript database

    The characteristics of fully developed turbulent flow in a hybrid domain channel, which consists of a clear fluid region and a porous bed, are examined numerically using a model based on the macroscopic Reynolds-averaged Navier–Stokes equations. By adopting the classical continuity interface conditi...

  11. Onset of centrifugal convection in a magnetic-fluid-saturated porous medium

    NASA Astrophysics Data System (ADS)

    Saravanan, S.; Yamaguchi, H.

    2005-08-01

    This paper concerns the influence of magnetic field on the onset of centrifugal convection in a magnetic-fluid-filled differentially heated porous layer placed in zero-gravity environment by linear stability theory. The axis of rotation of the layer is placed anywhere within its boundaries, which leads to an alternating direction of the centrifugal body force. The critical centrifugal Rayleigh number, the critical wave number, and the eigenfunctions corresponding to two-dimensional flow pattern at the threshold are calculated using a combination of analytical and numerical methods. Results show significant effects even for low magnetic-field strength when the axis location is located near the cold boundary. It is found that the magnetic field has a destabilizing effect and can be suitably adjusted depending on the axis location and particle magnetization to induce more developed convection currents.

  12. Liquifaction of fluid saturated rocks due to explosion-induced stress waves

    SciTech Connect

    Dey, T.N.; Brown, J.A.

    1990-01-01

    Shock-induced liquefaction of a water-saturated rock may occur during the passage of a large amplitude stress wave, such as that due to an explosive. We studied this phenomena numerically with the aid of a material model which incorporates effective stress principles, and experimentally with a gas gun. Our numerical model is capable of calculating material response for both small and large deformation and any initial saturation. Phase transitions of the solid phase and the water phase are also allowed. Fitting the model to dry gas gun experiments allowed reasonable predictions of nearly saturated experiments. Liquefaction, the loss of shear strength when pore pressure exceeds the mean stress, appears to occur during the unloading portion of these experiments. The pore crushing which occurs, even under fully saturated conditions, leads to greater attenuation of a stress wave, as well as liquefaction of the rock and a lengthening of the wave duration, as the wave passes. 12 refs., 4 figs.

  13. Analytical and numerical analysis of bifurcations in thermal convection of viscoelastic fluids saturating a porous square box

    NASA Astrophysics Data System (ADS)

    Taleb, A.; BenHamed, H.; Ouarzazi, M. N.; Beji, H.

    2016-05-01

    We report theoretical and numerical results on bifurcations in thermal instability for a viscoelastic fluid saturating a porous square cavity heated from below. The modified Darcy law based on the Oldroyd-B model was used for modeling the momentum equation. In addition to Rayleigh number ℜ, two more dimensionless parameters are introduced, namely, the relaxation time λ1 and the retardation time λ2. Temporal stability analysis showed that the first bifurcation from the conductive state may be either oscillatory for sufficiently elastic fluids or stationary for weakly elastic fluids. The dynamics associated with the nonlinear interaction between the two kinds of instabilities is first analyzed in the framework of a weakly nonlinear theory. For sufficiently elastic fluids, analytical expressions of the nonlinear threshold above which a second hysteretic bifurcation from oscillatory to stationary convective pattern are derived and found to agree with two-dimensional numerical simulations of the full equations. Computations performed with high Rayleigh number indicated that the system exhibits a third transition from steady single-cell convection to oscillatory multi-cellular flows. Moreover, we found that an intermittent oscillation regime may exist with steady state before the emergence of the secondary Hopf bifurcation. For weakly elastic fluids, we determined a second critical value ℜ2 Osc ( λ 1 , λ 2 ) above which a Hopf bifurcation from steady convective pattern to oscillatory convection occurs. The well known limit of ℜ2 Osc ( λ 1 = 0 , λ 2 = 0 ) = 390 for Newtonian fluids is recovered, while the fluid elasticity is found to delay the onset of the Hopf bifurcation. The major new findings were presented in the form of bifurcation diagrams as functions of viscoelastic parameters for ℜ up to 420.

  14. Analysis of matching conditions at the boundary surface of a fluid-saturated porous solid and a bulk fluid: the use of Lagrange multipliers

    NASA Astrophysics Data System (ADS)

    Kubik, J.; Cieszko, M.

    2005-12-01

    The compatibility conditions matching macroscopic mechanical fields at the contact surface between a fluid-saturated porous solid and an adjacent bulk fluid are considered. The general form of balance equations at that discontinuity surface are analyzed to obtain the compatibility conditions for the tangent and normal components of the velocity and the stress vector fields. Considerations are based on the procedure similar to that used in the phenomenological thermodynamics for derivation of constitutive relations, where the entropy inequality and the concept of Lagrange multipliers are applied. This procedure made possible to derive the compatibility conditions for the viscous fluid flowing tangentially and perpendicularly to the boundary surface of the porous solid and to formulate the generalized form of the so called slip condition for the fluid velocity field, postulated earlier by Beavers and Joseph, J. Fluid. Mech. 30, 197-207 (1967).

  15. Influence of phase connectivity on the relationship among capillary pressure, fluid saturation, and interfacial area in two-fluid-phase porous medium systems

    SciTech Connect

    McClure, James E.; Berrill, Mark A.; Gray, William G.; Miller, Cass T.

    2016-09-02

    Here, multiphase flow in porous medium systems is typically modeled using continuum mechanical representations at the macroscale in terms of averaged quantities. These models require closure relations to produce solvable forms. One of these required closure relations is an expression relating fluid pressures, fluid saturations, and, in some cases, the interfacial area between the fluid phases, and the Euler characteristic. An unresolved question is whether the inclusion of these additional morphological and topological measures can lead to a non-hysteretic closure relation compared to the hysteretic forms that are used in traditional models, which typically do not include interfacial areas, or the Euler characteristic. We develop a lattice-Boltzmann (LB) simulation approach to investigate the equilibrium states of a two-fluid-phase porous medium system, which include disconnected now- wetting phase features. The proposed approach is applied to a synthetic medium consisting of 1,964 spheres arranged in a random, non-overlapping, close-packed manner, yielding a total of 42,908 different equilibrium points. This information is evaluated using a generalized additive modeling approach to determine if a unique function from this family exists, which can explain the data. The variance of various model estimates is computed, and we conclude that, except for the limiting behavior close to a single fluid regime, capillary pressure can be expressed as a deterministic and non-hysteretic function of fluid saturation, interfacial area between the fluid phases, and the Euler characteristic. This work is unique in the methods employed, the size of the data set, the resolution in space and time, the true equilibrium nature of the data, the parameterizations investigated, and the broad set of functions examined. The conclusion of essentially non-hysteretic behavior provides support for an evolving class of two-fluid-phase flow in porous medium systems models.

  16. Influence of phase connectivity on the relationship among capillary pressure, fluid saturation, and interfacial area in two-fluid-phase porous medium systems

    DOE PAGES

    McClure, James E.; Berrill, Mark A.; Gray, William G.; ...

    2016-09-02

    Here, multiphase flow in porous medium systems is typically modeled using continuum mechanical representations at the macroscale in terms of averaged quantities. These models require closure relations to produce solvable forms. One of these required closure relations is an expression relating fluid pressures, fluid saturations, and, in some cases, the interfacial area between the fluid phases, and the Euler characteristic. An unresolved question is whether the inclusion of these additional morphological and topological measures can lead to a non-hysteretic closure relation compared to the hysteretic forms that are used in traditional models, which typically do not include interfacial areas, ormore » the Euler characteristic. We develop a lattice-Boltzmann (LB) simulation approach to investigate the equilibrium states of a two-fluid-phase porous medium system, which include disconnected now- wetting phase features. The proposed approach is applied to a synthetic medium consisting of 1,964 spheres arranged in a random, non-overlapping, close-packed manner, yielding a total of 42,908 different equilibrium points. This information is evaluated using a generalized additive modeling approach to determine if a unique function from this family exists, which can explain the data. The variance of various model estimates is computed, and we conclude that, except for the limiting behavior close to a single fluid regime, capillary pressure can be expressed as a deterministic and non-hysteretic function of fluid saturation, interfacial area between the fluid phases, and the Euler characteristic. This work is unique in the methods employed, the size of the data set, the resolution in space and time, the true equilibrium nature of the data, the parameterizations investigated, and the broad set of functions examined. The conclusion of essentially non-hysteretic behavior provides support for an evolving class of two-fluid-phase flow in porous medium systems models.« less

  17. Influence of phase connectivity on the relationship among capillary pressure, fluid saturation, and interfacial area in two-fluid-phase porous medium systems

    SciTech Connect

    McClure, James E.; Berrill, Mark A.; Gray, William G.; Miller, Cass T.

    2016-09-02

    Here, multiphase flow in porous medium systems is typically modeled using continuum mechanical representations at the macroscale in terms of averaged quantities. These models require closure relations to produce solvable forms. One of these required closure relations is an expression relating fluid pressures, fluid saturations, and, in some cases, the interfacial area between the fluid phases, and the Euler characteristic. An unresolved question is whether the inclusion of these additional morphological and topological measures can lead to a non-hysteretic closure relation compared to the hysteretic forms that are used in traditional models, which typically do not include interfacial areas, or the Euler characteristic. We develop a lattice-Boltzmann (LB) simulation approach to investigate the equilibrium states of a two-fluid-phase porous medium system, which include disconnected now- wetting phase features. The proposed approach is applied to a synthetic medium consisting of 1,964 spheres arranged in a random, non-overlapping, close-packed manner, yielding a total of 42,908 different equilibrium points. This information is evaluated using a generalized additive modeling approach to determine if a unique function from this family exists, which can explain the data. The variance of various model estimates is computed, and we conclude that, except for the limiting behavior close to a single fluid regime, capillary pressure can be expressed as a deterministic and non-hysteretic function of fluid saturation, interfacial area between the fluid phases, and the Euler characteristic. This work is unique in the methods employed, the size of the data set, the resolution in space and time, the true equilibrium nature of the data, the parameterizations investigated, and the broad set of functions examined. The conclusion of essentially non-hysteretic behavior provides support for an evolving class of two-fluid-phase flow in porous medium systems models.

  18. Influence of phase connectivity on the relationship among capillary pressure, fluid saturation, and interfacial area in two-fluid-phase porous medium systems

    NASA Astrophysics Data System (ADS)

    McClure, James E.; Berrill, Mark A.; Gray, William G.; Miller, Cass T.

    2016-09-01

    Multiphase flows in porous medium systems are typically modeled at the macroscale by applying the principles of continuum mechanics to develop models that describe the behavior of averaged quantities, such as fluid pressure and saturation. These models require closure relations to produce solvable forms. One of these required closure relations is an expression relating the capillary pressure to fluid saturation and, in some cases, other topological invariants such as interfacial area and the Euler characteristic (or average Gaussian curvature). The forms that are used in traditional models, which typically consider only the relationship between capillary pressure and saturation, are hysteretic. An unresolved question is whether the inclusion of additional morphological and topological measures can lead to a nonhysteretic closure relation. Relying on the lattice Boltzmann (LB) method, we develop an approach to investigate equilibrium states for a two-fluid-phase porous medium system, which includes disconnected nonwetting phase features. A set of simulations are performed within a random close pack of 1964 spheres to produce a total of 42 908 distinct equilibrium configurations. This information is evaluated using generalized additive models to quantitatively assess the degree to which functional relationships can explain the behavior of the equilibrium data. The variance of various model estimates is computed, and we conclude that, except for the limiting behavior close to a single fluid regime, capillary pressure can be expressed as a deterministic and nonhysteretic function of fluid saturation, interfacial area between the fluid phases, and the Euler characteristic. To our knowledge, this work is unique in the methods employed, the size of the data set, the resolution in space and time, the true equilibrium nature of the data, the parametrizations investigated, and the broad set of functions examined. The conclusion of essentially nonhysteretic behavior provides

  19. Influence of phase connectivity on the relationship among capillary pressure, fluid saturation, and interfacial area in two-fluid-phase porous medium systems.

    PubMed

    McClure, James E; Berrill, Mark A; Gray, William G; Miller, Cass T

    2016-09-01

    Multiphase flows in porous medium systems are typically modeled at the macroscale by applying the principles of continuum mechanics to develop models that describe the behavior of averaged quantities, such as fluid pressure and saturation. These models require closure relations to produce solvable forms. One of these required closure relations is an expression relating the capillary pressure to fluid saturation and, in some cases, other topological invariants such as interfacial area and the Euler characteristic (or average Gaussian curvature). The forms that are used in traditional models, which typically consider only the relationship between capillary pressure and saturation, are hysteretic. An unresolved question is whether the inclusion of additional morphological and topological measures can lead to a nonhysteretic closure relation. Relying on the lattice Boltzmann (LB) method, we develop an approach to investigate equilibrium states for a two-fluid-phase porous medium system, which includes disconnected nonwetting phase features. A set of simulations are performed within a random close pack of 1964 spheres to produce a total of 42 908 distinct equilibrium configurations. This information is evaluated using generalized additive models to quantitatively assess the degree to which functional relationships can explain the behavior of the equilibrium data. The variance of various model estimates is computed, and we conclude that, except for the limiting behavior close to a single fluid regime, capillary pressure can be expressed as a deterministic and nonhysteretic function of fluid saturation, interfacial area between the fluid phases, and the Euler characteristic. To our knowledge, this work is unique in the methods employed, the size of the data set, the resolution in space and time, the true equilibrium nature of the data, the parametrizations investigated, and the broad set of functions examined. The conclusion of essentially nonhysteretic behavior provides

  20. Analysis of the Laminar Newtonian Fluid Flow Through a Thin Fracture Modelled as a Fluid-Saturated Sparsely Packed Porous Medium

    NASA Astrophysics Data System (ADS)

    Pažanin, Igor; Siddheshwar, Pradeep G.

    2017-03-01

    In this article we investigate the fluid flow through a thin fracture modelled as a fluid-saturated porous medium. We assume that the fracture has constrictions and that the flow is governed by the prescribed pressure drop between the edges of the fracture. The problem is described by the Darcy-Lapwood-Brinkman model acknowledging the Brinkman extension of the Darcy law as well as the flow inertia. Using asymptotic analysis with respect to the thickness of the fracture, we derive the explicit higher-order approximation for the velocity distribution. We make an error analysis to comment on the order of accuracy of the method used and also to provide rigorous justification for the model.

  1. The equivalence of quasistatic flow in fluid-saturated porous media and Biot's slow wave in the limit of zero frequency

    NASA Astrophysics Data System (ADS)

    Chandler, Richard N.; Johnson, David Linton

    1981-05-01

    We have established in a simple and straightforward fashion that the analysis of quasistatic flow in fluid-saturated porous media due to Rice and Cleary is derivable from the low-frequency limit of Biot's slow compressional/diffusive mode. The single material parameter of the problem, the diffusivity, is simply related to the bulk and shear moduli and permeability of the skeletal frame and to the viscous and elastic properties of the constitutive media. Since this common theory treats fluid and solid displacements on an equal footing, it is the most general linearized description of the problem; other treatments are special cases. These latter include the rigid frame approximation used in the petroleum industry and the weak frame approximation used by De Gennes to describe the motion of polymer gels.

  2. Thermal convection of magneto compressible couple-stress fluid saturated in a porous medium with Hall current

    NASA Astrophysics Data System (ADS)

    Mehta, C. B.; Singh, M.; Kumar, S.

    2016-02-01

    An investigation is made on the effect of Hall currents on thermal instability of a compressible couple-stress fluid in the presence of a horizontal magnetic field saturated in a porous medium. The analysis is carried out within the framework of the linear stability theory and normal mode technique. A dispersion relation governing the effects of viscoelasticity, Hall currents, compressibility, magnetic field and porous medium is derived. For the stationary convection a couple-stress fluid behaves like an ordinary Newtonian fluid due to the vanishing of the viscoelastic parameter. Compressibility, the magnetic filed and couple-stress parameter have stabilizing effects on the system whereas Hall currents and medium permeability have a destabilizing effect on the system, but in the absence of Hall current couple-stress has a destabilizing effect on the system. It has been observed that oscillatory modes are introduced due to the presence of viscoelasticity, magnetic field porous medium and Hall currents which were non-existent in their absence.

  3. Full frequency-range transient solution for compressional waves in a fluid-saturated viscoacoustic porous medium

    SciTech Connect

    Carcione, J.M.; Quiroga-Goode, G.

    1996-01-01

    An analytical transient solution is obtained for propagation of compressional waves in a homogeneous porous dissipative medium. The solution, based on a generalization of Biot`s poroelastic equations, holds for the low- and high-frequency ranges, and includes viscoelastic phenomena of a very general nature, besides the Biot relaxation mechanism. The viscodynamic operator is used to model the dynamic behavior associated with the relative motion of the fluid in the pores at all frequency ranges. Viscoelasticity is introduced through the standard linear solid which allows the modeling of a general relaxation spectrum. The solution is used to study the influence of the material properties, such as bulk moduli, porosity, viscosity, permeability and intrinsic attenuation, on the kinematic and dynamic characteristics of the two compressional waves supported by the medium. The authors also obtain snapshots of the static mode arising from the diffusive behavior of the slow wave at low frequencies.

  4. Biogenic Cracks in Porous Rock

    NASA Astrophysics Data System (ADS)

    Hemmerle, A.; Hartung, J.; Hallatschek, O.; Goehring, L.; Herminghaus, S.

    2014-12-01

    Microorganisms growing on and inside porous rock may fracture it by various processes. Some of the mechanisms of biofouling and bioweathering are today identified and partially understood but most emphasis is on chemical weathering, while mechanical contributions have been neglected. However, as demonstrated by the perseverance of a seed germinating and cracking up a concrete block, the turgor pressure of living organisms can be very significant. Here, we present results of a systematic study of the effects of the mechanical forces of growing microbial populations on the weathering of porous media. We designed a model porous medium made of glass beads held together by polydimethylsiloxane (PDMS), a curable polymer. The rheological properties of the porous medium, whose shape and size are tunable, can be controlled by the ratio of crosslinker to base used in the PDMS (see Fig. 1). Glass and PDMS being inert to most chemicals, we are able to focus on the mechanical processes of biodeterioration, excluding any chemical weathering. Inspired by recent measurements of the high pressure (~0.5 Mpa) exerted by a growing population of yeasts trapped in a microfluidic device, we show that yeast cells can be cultured homogeneously within porous medium until saturation of the porous space. We investigate then the effects of such an inner pressure on the mechanical properties of the sample. Using the same model system, we study also the complex interplay between biofilms and porous media. We focus in particular on the effects of pore size on the penetration of the biofilm within the porous sample, and on the resulting deformations of the matrix, opening new perspectives into the understanding of life in complex geometry. Figure 1. Left : cell culture growing in a model porous medium. The white spheres represent the grains, bonds are displayed in grey, and microbes in green. Right: microscopy picture of glass beads linked by PDMS bridges, scale bar: 100 μm.

  5. Conditional stability for thermal convection in a rotating couple-stress fluid saturating a porous media with temperature- and pressure-dependent viscosity using a thermal non-equilibrium model

    NASA Astrophysics Data System (ADS)

    Sunil; Choudhary, Shalu; Mahajan, Amit

    2014-06-01

    A nonlinear stability threshold for convection in a rotating couple-stress fluid saturating a porous medium with temperature- and pressure-dependent viscosity using a thermal non-equilibrium model is found to be exactly the same as the linear instability boundary. This optimal result is important because it shows that linear theory has completely captured the physics of the onset of convection. The effects of couple-stress fluid parameter F, temperature- and pressure-dependent viscosity Γ, interface heat transfer coefficient H, Taylor number TA, Darcy-Brinkman number D˜a, and porosity modified conductivity ratio γ on the onset of convection have been investigated. Asymptotic analysis for both small and large values of interface heat transfer coefficient H is also presented. An excellent agreement is found between the exact solutions and asymptotic solutions.

  6. The Time-Dependency of Deformation in Porous Carbonate Rocks

    NASA Astrophysics Data System (ADS)

    Kibikas, W. M.; Lisabeth, H. P.; Zhu, W.

    2016-12-01

    Porous carbonate rocks are natural reservoirs for freshwater and hydrocarbons. More recently, due to their potential for geothermal energy generation as well as carbon sequestration, there are renewed interests in better understanding of the deformation behavior of carbonate rocks. We conducted a series of deformation experiments to investigate the effects of strain rate and pore fluid chemistry on rock strength and transport properties of porous limestones. Indiana limestone samples with initial porosity of 16% are deformed at 25 °C under effective pressures of 10, 30, and 50 MPa. Under nominally dry conditions, the limestone samples are deformed under 3 different strain rates, 1.5 x 10-4 s-1, 1.5 x 10-5 s-1 and 1.5 x 10-6 s-1 respectively. The experimental results indicate that the mechanical behavior is both rate- and pressure-dependent. At low confining pressures, post-yielding deformation changes from predominantly strain softening to strain hardening as strain rate decreases. At high confining pressures, while all samples exhibit shear-enhanced compaction, decreasing strain rate leads to an increase in compaction. Slower strain rates enhance compaction at all confining pressure conditions. The rate-dependence of deformation behaviors of porous carbonate rocks at dry conditions indicates there is a strong visco-elastic coupling for the degradation of elastic modulus with increasing plastic deformation. In fluid saturated samples, inelastic strain of limestone is partitioned among low temperature plasticity, cataclasis and solution transport. Comparison of inelastic behaviors of samples deformed with distilled water and CO2-saturated aqueous solution as pore fluids provide experimental constraints on the relative activities of the various mechanisms. Detailed microstructural analysis is conducted to take into account the links between stress, microstructure and the inelastic behavior and failure mechanisms.

  7. Conditional stability for thermal convection in a rotating couple-stress fluid saturating a porous medium with temperature and pressure dependent viscosity

    NASA Astrophysics Data System (ADS)

    Sunil; Choudhary, Shalu; Mahajan, Amit

    2013-08-01

    A nonlinear stability threshold for rotation in a couple-stress fluid heated from below saturating a porous medium with temperature and pressure dependent viscosity is exactly the same as the linear instability boundary. This optimal result is important because it shows that linearized instability theory has captured completely the physics of the onset of convection. The effects of couple-stress parameter, variable dependent viscosity, medium permeability, Taylor number and Darcy-Brinkman number on the onset of convection are also analysed.

  8. Pore-Scale Study of the Effect of the Saturation History on Fluid Saturation and Relative Permeability of Three-Fluid Flow in Porous Media

    NASA Astrophysics Data System (ADS)

    Hsu, S. Y.; Tsai, J. P.; Chang, L. C.

    2014-12-01

    The flow of three immiscible fluids - water, NAPL, air - in porous media is important in many subsurface processes. To model the three-fluid flow, the relation of relative permeability-saturation-capillary pressure (k-S-P) of three fluids is of central importance. In this experimental study, we directly measure the k-S-P of the water (wetting phase) when three fluids are coexist in a micromodel during the water drainage and imbibition. The results show that the sequence of the non-wetting fluids (air and NAPL) entering into the micromodel affects the fluid distributions as well as the relative permeability of water. During the drainage process, the relative permeability of water dropped drastically when the pathway of water from inlet to outlet of the micromodel was visually blocked by the non-wetting fluids. At this stage, the relative permeability of water was low but not down to zero. The water was still able to move via corner flows or thin-film flows. During the imbibition process, the water displaced two non-wetting liquids via both "snap-off" and "piston-type" motions. The relative permeability of water jumped when the water pathway was formed again. In addition, we found that the well-known scaling format proposed by Parker et al. [1] might fail when the interfaces between the most non-wetting (air) and the most wetting (water) fluids occurs in the three-fluids system. References[1] J. C. Parker, R. J. Lenhard, and T. Kuppusamy, Water Resources Research, 23, 4, 618-624 (1987)

  9. Quantifying solid-fluid interfacial phenomena in porous rocks with proton nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Schmidt, Ehud J.; Velasco, Katherine K.; Nur, Amos M.

    1986-04-01

    The three order-of-magnitude variation in the proton nuclear magnetic resonance (NMR) longitudinal relaxation time T1 of water adsorbed on silica surfaces versus that of bulk water makes proton NMR studies of porous materials powerful tools to study the effects of adsorption. Recent theory permits the utilization of this different response to obtain pore space surface-to-volume (S/V) distribution functions by inverting the decay of the z component of magnetization of fully saturated porous rocks; information can likewise be obtained on the fluid distribution at partially saturated conditions. A computer program has been developed to invert the NMR relaxation curves for the S/V distribution function, assuming an isolated pore regime, the ramifications of which are examined. The program has been applied to experimental results from water, porous sandstones, and tight gas sands at various pore fluid saturations and varying electrolyte content. For the fully saturated case, the results show promise in the application of NMR to describing pore space geometries in rock samples with widely varying surface-to-volume ratios. For partially saturated rocks, the results reflect the preferential early draining of the large pores at high water saturations, connectivity percolation phenomena at intermediate saturations, and the dominating role of adsorbed water films at low water saturations. Experiments on rocks saturated with saline solutions disclose the importance of the effects of alteration of the active sites on the rock surfaces as well as the role of electrolytes in modifying the structural properties of bulk solution.

  10. Conditions for compaction bands in porous rock

    NASA Astrophysics Data System (ADS)

    Issen, K. A.; Rudnicki, J. W.

    2000-09-01

    Reexamination of the results of Rudnicki and Rice for shear localization reveals that solutions for compaction bands are possible in a range of parameters typical of porous rock. Compaction bands are narrow planar zones of localized compressive deformation perpendicular to the maximum compressive stress, which have been observed in high-porosity rocks in the laboratory and field. Solutions for compaction bands, as an alternative to homogenous deformation, are possible when the inelastic volume deformation is compactive and is associated with stress states on a yield surface "cap." The cap implies that the shear stress required for further inelastic deformation decreases with increasing compressive mean stress. While the expressions for the critical hardening modulus for compaction and shear bands differ, in both cases, deviations from normality promote band formation. Inelastic compaction deformation associated with mean stress (suggested by Aydin and Johnson) promotes localization by decreasing the magnitude of the critical hardening modulus. Axisymmetric compression is the most favorable deviatoric stress state for formation of compaction bands. Predictions for compaction bands suggest that they could form on the "shelf" typically observed in axisymmetric compression stress strain curves of porous rock at high confining stress. Either shear or compaction bands may occur depending on the stress path and confining stress. If the increase in local density and decrease in grain size associated with compaction band formation result in strengthening rather than weakening of the band material, formation of a compaction band may not preclude later formation of a shear band.

  11. [Investigation of ultrasonic surface wave interaction with porous saturated rocks]. Progress report, [July 1, 1993--June 30, 1994

    SciTech Connect

    Not Available

    1994-06-01

    Calculations showed that capillary forces can easily produce closed- pore boundary conditions at interface between nonwetting fluid (air) and a porous solid saturated by a wetting fluid (water). The direct excitation technique was used to measure surface wave velocity and attenuation on both wet and dry rocks. The strong correlation between the observed surface wave velocity change caused by water saturation and the formation permeability can be used for ultrasonic assessment of the dynamic permeability. The experimental system was improved further by introducing laser interferometric detection, which was adapted to surface wave inspection of fluid-saturated permeable materials. In a separate effort, the surface stiffness of different water-saturated porous solids was studied by a novel acoustical method. Areas for further study are described.

  12. Theoretical and numerical aspects of fluid-saturated elasto-plastic soils

    SciTech Connect

    Ehlers, W.

    1995-12-31

    The theoretical and numerical treatment of fluid-saturated porous solid materials generally falls into the category of porous media models, which are described within the framework of the classical theory of mixtures extended by the concept of volume fractions (porous media theories). In particular, this concept allows for the description of saturated, unsaturated and empty porous matrix materials, thus offering a well-founded theoretical background for a lot of engineering problems occurring, for instance, in the fields of geomechanics (soil and rock mechanics as well as glacier and rock ice mechanics), oil producing industries, sintering technologies, biomechanics, etc. In the present contribution, theoretical and numerical studies are outlined to describe a two-phase material composed of an incompressible elasto-plastic soil matrix saturated by an incompressible viscous pore fluid. In this context, the phenomenon of phase incompressibility is well known as a microscopic effect not implying bulk incompressibility in the macro regime. This is seen from the fact that even if the material density functions of the individual constituents are constant during deformation, the corresponding bulk densities can still change through changes in the volume fractions. Within the framework of a pure mechanical theory, constitutive equations are given for both the solid and the fluid partial stress tensors and for the interaction force acting between the two materials. Concerning the porous soil matrix, the elastic properties are described by an elasticity law of Hookean type, while the plastic range is governed by a {open_quote}single surface{close_quote} yield function exhibiting a smooth and closed shape in the principal stress space together with a non-associated flow rule. The viscosity effects of the pore fluid are included in the fluid stress tensor and in the drag force.

  13. Microplane constitutive model for porous isotropic rocks

    NASA Astrophysics Data System (ADS)

    Baant, Zdenk P.; Zi, Goangseup

    2003-01-01

    The paper deals with constitutive modelling of contiguous rock located between rock joints. A fully explicit kinematically constrained microplane-type constitutive model for hardening and softening non-linear triaxial behaviour of isotropic porous rock is developed. The microplane framework, in which the constitutive relation is expressed in terms of stress and strain vectors rather than tensors, makes it possible to model various microstructural physical mechanisms associated with oriented internal surfaces, such as cracking, slip, friction and splitting of a particular orientation. Formulation of the constitutive relation is facilitated by the fact that it is decoupled from the tensorial invariance restrictions, which are satisfied automatically. In its basic features, the present model is similar to the recently developed microplane model M4 for concrete, but there are significant improvements and modifications. They include a realistic simulation of (1) the effects of pore collapse on the volume changes during triaxial loading and on the reduction of frictional strength, (2) recovery of frictional strength during shearing, and (3) the shear-enhanced compaction in triaxial tests, manifested by a deviation from the hydrostatic stress-strain curve. The model is calibrated by optimal fitting of extensive triaxial test data for Salem limestone, and good fits are demonstrated. Although these data do not cover the entire range of behaviour, credence in broad capabilities of the model is lend by its similarity to model M4 for concrete - an artificial rock. The model is intended for large explicit finite-element programs.

  14. Dynamic flow localization in porous rocks under combined pressure and shear loading

    NASA Astrophysics Data System (ADS)

    Yarushina, Viktoriya; Podladchikov, Yuri; Simon, Nina

    2015-04-01

    Flow localization occurs in deforming porous fluid saturated rocks. It exhibits itself as veins, pockmarks on the ocean floor or gas chimneys visible on seismic images from several chalk fields of the Central North Sea and from the Utsira formation at Sleipner in the Norwegian North Sea, which is one of the best documented CO2 storage sites. Porosity waves were repeatedly shown to be a viable mechanism of flow self-localization that does not require the pre-existence of a connected fracture network. Porosity waves result from an instability of the Darcy flow that occurs in porous rocks with time-dependent viscous or viscoelastoplastic rheology. Local fluid overpressure generated by fluid injection or chemical reactions aided by buoyancy force drives upward fluid migration. Viscous deformation delays pressure diffusion thus maintaining local overpressure for considerable periods of time. Development of an under-pressured region just below the over-pressured domain leads to separation of the fluid-filled high-porosity blob from the source and the background flow. The instability organizes the flow into separate vertical channels. Pressure distribution, shape and scaling of these channels are highly sensitive to the rheology of the porous rock. In this contribution, based on a micromechanical approach, we consider the complex rheology of brittle, ductile and transitional regimes of deformation of porous rocks in the presence of combined pressure and shear loading. Accurate description of transitional brittle-ductile deformation is a challenging task due to a large number of microscopic processes involved. We use elastoplastic and viscoplastic analytical solutions for the non-hydrostatic deformation of a singular cavity in the representative volume element in order to deduce expected behavior of the porous rock. The model provides micro-mechanisms for various failure modes (localized and homogeneous) and dilatancy onset. In particular, the model predicts that dilatancy

  15. Frequency-dependent processing and interpretation (FDPI) of seismic data for identifying, imaging and monitoring fluid-saturated underground reservoirs

    DOEpatents

    Goloshubin, Gennady M.; Korneev, Valeri A.

    2005-09-06

    A method for identifying, imaging and monitoring dry or fluid-saturated underground reservoirs using seismic waves reflected from target porous or fractured layers is set forth. Seismic imaging the porous or fractured layer occurs by low pass filtering of the windowed reflections from the target porous or fractured layers leaving frequencies below low-most corner (or full width at half maximum) of a recorded frequency spectra. Additionally, the ratio of image amplitudes is shown to be approximately proportional to reservoir permeability, viscosity of fluid, and the fluid saturation of the porous or fractured layers.

  16. Frequency-dependent processing and interpretation (FDPI) of seismic data for identifying, imaging and monitoring fluid-saturated underground reservoirs

    DOEpatents

    Goloshubin, Gennady M.; Korneev, Valeri A.

    2006-11-14

    A method for identifying, imaging and monitoring dry or fluid-saturated underground reservoirs using seismic waves reflected from target porous or fractured layers is set forth. Seismic imaging the porous or fractured layer occurs by low pass filtering of the windowed reflections from the target porous or fractured layers leaving frequencies below low-most corner (or full width at half maximum) of a recorded frequency spectra. Additionally, the ratio of image amplitudes is shown to be approximately proportional to reservoir permeability, viscosity of fluid, and the fluid saturation of the porous or fractured layers.

  17. Fluid-dependent anisotropy and experimental measurements in synthetic porous rocks with controlled fracture parameters

    NASA Astrophysics Data System (ADS)

    Ding, Pinbo; Di, Bangrang; Wei, Jianxin; Li, Xiangyang; Deng, Yinghua

    2014-02-01

    In this study, we analyse the influence of fluid on P- and S-wave anisotropy in a fractured medium. Equivalent medium theories are used to describe the relationship between the fluid properties and the rock physics characteristics in fractured rocks, and P-wave and S-wave velocities and anisotropy are considered to be influenced by fluid saturation. However, these theoretical predictions require experimental measurement results for calibration. A new construction method was used to create synthetic rock samples with controlled fracture parameters. The new construction process provides synthetic rocks that have a more realistic mineral composition, porous structure, cementation and pressure sensitivity than samples used in previous research on fractured media. The synthetic rock samples contain fractures which have a controlled distribution, diameter, thickness and fracture density. In this study, the fracture diameter was about 4 mm, the thickness of fractures was about 0.06 mm, and the fracture density in the two fractured rock samples was about 3.45%. SEM images show well-defined penny-shaped fractures of 4 mm in length and 0.06 mm in width. The rock samples were saturated with air, water and oil, and P- and S-wave velocities were measured in an ultrasonic measurement system. The laboratory measurement results show that the P-wave anisotropy is strongly influenced by saturated fluid, and the P-wave anisotropy parameter, ɛ, has a much larger value in air saturation than in water and oil saturations. The S-wave anisotropy decreases when the samples are saturated with oil, which can be caused by high fluid viscosity. In the direction perpendicular to the fractures (the 0° direction), shear-wave splitting is negligible, and is similar to the blank sample without fractures, as expected. In the direction parallel to the fractures (the 90° direction) shear-wave splitting is significant. The fractured rock samples show significant P- and S-wave anisotropy caused by

  18. A modeling solution for predicting (a) dry rock bulk modulus, rigidity modulus and (b) seismic velocities and reflection coefficients in porous, fluid-filled rocks with applications to laboratory rock samples and well logs

    NASA Astrophysics Data System (ADS)

    Benson, Alvin K.; Wu, Jie

    1999-02-01

    The velocity of sound in porous, fluid-saturated rocks can be predicted using the Biot-Geertsma-Gassmann (BGG) and shear-wave velocity equations. However, two of the needed input parameters, the bulk modulus ( Kb) of the empty, porous rock and the shear modulus ( μ) of the rock are very difficult to obtain in situ. In the past, these values were typically chosen a priori and input into the BGG and shear-wave equations in a forward modeling mode. In addition to Kb and μ, it is also essential to input rock-matrix and fluid parameters that reflect in situ conditions. In this paper, the BGG and shear-wave equations are inverted to generate values for Kb and μ, respectively, by using available velocity and porosity data obtained from well logs and/or cores for water/brine-saturated rocks. These values of Kb and μ, along with reasonable in situ estimates of rock-matrix and fluid parameters generated from the Batzle-Wang [Batzle, M., Wang, Z., 1992. Seismic properties of pore fluids. Geophysics 57, 1396-1408.] formulation, are then used to predict compressional and shear-wave velocities, compressional-shear wave ratios, and reflection coefficients at the interfaces between host rocks and fluid-saturated rocks, either fully or partially saturated with hydrocarbons, as a function of depth and/or porosity. Although generally similar to the approach of Murphy et al. [Murphy, W.F., Reischer, A., Hsu, K., 1993. Modulus decomposition of compressional and shear velocities in sand bodies. Geophysics 58, 227-239.], our method of inversion to determine Kb and μ, coupled with our input of in situ estimates of rock-matrix and fluid parameters as a function of depth from the Batzle-Wang formulation, forms a novel solution for predicting in situ velocities. A modeling program has been developed to perform these calculations and plot the velocity and reflection coefficient information as a function of depth, porosity, and water saturation. The resulting relationships between porous

  19. Digital Rock Studies of Tight Porous Media

    SciTech Connect

    Silin, Dmitriy

    2012-08-07

    This technical report summarizes some recently developed approaches to studies of rock properties at a pore scale. Digital rock approach is complementary to laboratory and field studies. It can be especially helpful in situations where experimental data are uncertain, or are difficult or impossible to obtain. Digitized binary images of the pore geometries of natural rocks obtained by different imaging techniques are the input data. Computer-generated models of natural rocks can be used instead of images in a case where microtomography data are unavailable, or the resolution of the tools is insufficient to adequately characterize the features of interest. Simulations of creeping viscous flow in pores produce estimates of Darcy permeability. Maximal Inscribed Spheres calculations estimate two-phase fluid distribution in capillary equilibrium. A combination of both produce relative permeability curves. Computer-generated rock models were employed to study two-phase properties of fractured rocks, or tight sands with slit-like pores, too narrow to be characterized with micro-tomography. Various scenarios can simulate different fluid displacement mechanisms, from piston-like drainage to liquid dropout at the dew point. A finite differences discretization of Stokes equation is developed to simulate flow in the pore space of natural rocks. The numerical schemes are capable to handle both no-slip and slippage flows. An upscaling procedure estimates the permeability by subsampling a large data set. Capillary equilibrium and capillary pressure curves are efficiently estimated with the method of maximal inscribed spheres both an arbitrary contact angle. The algorithms can handle gigobytes of data on a desktop workstation. Customized QuickHull algorithms model natural rocks. Capillary pressure curves evaluated from computer-generated images mimic those obtained for microtomography data.

  20. Mass transfer and transport of radionuclides in fractured porous rock

    SciTech Connect

    Ahn, Joonhong

    1988-04-01

    Analytical studies are made to predict space-time dependent concentrations of radionuclides transported through water-saturated fractured porous rock. A basic model, which is expected to generate conservative results when used in long-term safety assessment of geologic repositories for radioactive waste, is established. Applicability and limitations of the model are investigated. 67 refs., 54 figs., 3 tabs.

  1. [Investigation of ultrasonic wave interaction with porous saturated rocks

    SciTech Connect

    Not Available

    1993-07-01

    During the last year we have continued our investigation of ultrasonic wave propagation in fluid-filled porous materials. Previously, we studied the feasibility of using different surface modes to characterize both synthetic and natural rocks. We introduced a novel experimental technique based on the direct generation of surface waves by edge excitation. At first, we used two low-frequency (100--500 kHz) shear transducers in pitch-catch mode to launch and receive the ultrasonic surface wave. The contact transducers were coupled to the opposite edges of the porous specimens with normal polarization relative to the surface. The same technique was successfully used to generate Rayleigh-type surface modes on the free surface of both dry and water-saturated specimens, as well as Stoneley-type interface modes on the fluid-loaded surfaces of immersed samples. Recently, we developed a special interferometric technique for non-contact detection of ultrasonic vibrations on diffusely reflecting rough surfaces. This method was found to be more suitable for surface wave inspection of porous ceramics and natural rocks than the previously used contact techniques. Beside investigating guided acoustic waves in water-saturated porous materials, we also studied bulk wave propagation in air-saturated specimens. We further developed our experimental technique which is based on the transmission of airborne ultrasonic waves through air-filled porous plates. This method can be readily used to study the frequency-dependent propagation properties of slow compressional waves in different porous materials including natural rocks. By simple technical improvements, we extended the measuring range so that we could continuously cover both low-frequency (diffuse) and high-frequency (propagating) regimes of slow wave propagation.

  2. Seismic stress mobilization of natural colloids in a porous rock

    SciTech Connect

    Roberts, Peter M; Abdel-fattah, Amr I

    2008-01-01

    Stress oscillations at 26 Hz enhanced the release of natural micro-particles (colloids) in a porous rock sample. Micron-scale effects were induced by meter-scale wavelengths. The results are attributed to altering the release rate coefficient for colloids trapped in pores. The rate change did not depend on colloid size and thus is not due to altering colloid-pore-wall interactions. Enhanced colloid detachment from pore walls and flushing from dead-end pores are likely mechanisms. This phenomenon could impact a broad range of physical sciences involving colloid dynamics and porous transport.

  3. Fracture and Faulting Induced Permeability Change in Porous Sedimentary Rocks

    NASA Astrophysics Data System (ADS)

    Zhu, W.-L.

    2012-04-01

    Flow of interstitial fluids exerts important control over seismogenic, sedimentary, and metamorphic processes. Since the seminal work of Hubbert and Rubey [1959] on the motion of thrust sheet, elevated pore fluid pressure has been used to reconcile the heat flow paradox during seismogenic faulting, and more recently, as a possible mechanism for slow slip events observed at subduction zones. Many working hypotheses for generating and maintaining high pore fluid pressure have been proposed. However, one important ingredient still missing in these models is quantitative knowledge of permeability as a dynamics physical property that varies significantly in different tectonic settings. In this study, we conducted systematic laboratory characterization of how permeability and its anisotropy evolve as porous sandstones and limestones undergo the transition from brittle faulting to cataclastic flow. Our data show that highly porous silicate rocks experience permeability reduction during dilatant brittle fracture whereas their low porosity counterparts exhibit permeability enhancement. With increasing confinement, brittle fracture is inhibited and the porous rocks exhibit shear enhanced compaction, resulting in significant porosity reduction accompanied by strain hardening and drastic loss of permeability. Hertzian fracture and pore collapse are the primary micomechanisms responsible for the brittle faulting or pervasive fracturing in porous silicate rocks. In contrast, the stress-induced permeability evolution in porous limestones is markedly different. Because crystal plasticity as well as solution transfer can be activated at relatively low temperatures in calcite compared to quartz, the inelastic behavior and failure mode of carbonate rocks are not only a function of pressure, but also sensitive to temperature. Laboratory measurements show that the presence of water enhances compaction and considerably lower the yield strength of carbonate rocks. The yield cap is

  4. Modelling karst aquifer evolution in fractured, porous rocks

    NASA Astrophysics Data System (ADS)

    Kaufmann, Georg

    2016-12-01

    The removal of material in soluble rocks by physical and chemical dissolution is an important process enhancing the secondary porosity of soluble rocks. Depending on the history of the soluble rock, dissolution can occur either along fractures and bedding partings of the rock in the case of a telogenetic origin, or within the interconnected pore space in the case of eogenetic origin. In soluble rocks characterised by both fractures and pore space, dissolution in both flow compartments is possible. We investigate the dissolution of calcite both along fractures and within the pore space of a limestone rock by numerical modelling. The limestone rock is treated as fractured, porous aquifer, in which the hydraulic conductivity increases with time both for the fractures and the pore spaces. We show that enlargement of pore space by dissolution will accelerate the development of a classical fracture-dominated telogenetic karst aquifer, breakthrough occurs faster. In the case of a pore-controlled aquifer as in eogenetic rocks, enlargement of pores results in a front of enlarged pore spaces migrating into the karst aquifer, with more homogeneous enlargement around this dissolution front, and later breakthrough.

  5. Capturing poromechanical coupling effects of the reactive fracturing process in porous rock via a DEM-network model

    NASA Astrophysics Data System (ADS)

    Ulven, Ole Ivar; Sun, WaiChing

    2016-04-01

    Fluid transport in a porous medium has important implications for understanding natural geological processes. At a sufficiently large scale, a fluid-saturated porous medium can be regarded as a two-phase continuum, with the fluid constituent flowing in the Darcian regime. Nevertheless, a fluid mediated chemical reaction can in some cases change the permeability of the rock locally: Mineral dissolution can cause increased permeability, whereas mineral precipitation can reduce the permeability. This might trigger a complicated hydro-chemo-mechanical coupling effect that causes channeling of fluids or clogging of the system. If the fluid is injected or produced at a sufficiently high rate, the pressure might increase enough to cause the onset and propagation of fractures. Fractures in return create preferential flow paths that enhance permeability, localize fluid flow and chemical reaction, prevent build-up of pore pressure and cause anisotropy of the hydro-mechanical responses of the effective medium. This leads to a complex coupled process of solid deformation, chemical reaction and fluid transport enhanced by the fracture formation. In this work, we develop a new coupled numerical model to study the complexities of feedback among fluid pressure evolution, fracture formation and permeability changes due to a chemical process in a 2D system. We combine a discrete element model (DEM) previously used to study a volume expanding process[1, 2] with a new fluid transport model based on poroelasticity[3] and a fluid-mediated chemical reaction that changes the permeability of the medium. This provides new insights into the hydro-chemo-mechanical process of a transforming porous medium. References [1] Ulven, O. I., Storheim, H., Austrheim, H., and Malthe-Sørenssen, A. "Fracture Initiation During Volume Increasing Reactions in Rocks and Applications for CO2 Sequestration", Earth Planet. Sc. Lett. 389C, 2014a, pp. 132 - 142, doi:10.1016/j.epsl.2013.12.039. [2] Ulven, O. I

  6. Seismic Absorption and Modulus Measurements in Porous Rocks Under Fluid and Gas Flow-Physical and Chemical Effects: a Laboratory Study

    SciTech Connect

    Harmut Spetzler

    2005-11-28

    This paper describes the culmination of a research project in which we investigated the complex modulus change in partially fluid saturated porous rocks. The investigation started with simple flow experiments over ''clean'' and ''contaminated'' surfaces, progressed to moduli measurements on partially filled single cracks, to measurements in ''clean'' and ''contaminated'' porous rocks and finally to a feasibility study in the field. For the experiments with the simple geometries we were able to measure fundamental physical properties such as contact angles of the meniscus and time dependent forces required to get the meniscus moving and to keep it moving at various velocities. From the data thus gathered we were able to interpret the complex elastic moduli data we measured in the partially saturated single cracks. While the geometry in real rocks is too complex to make precise calculations we determined that we had indeed identified the mechanisms responsible for the changes in the moduli we had measured. Thus encouraged by the laboratory studies we embarked on a field experiment in the desert of Arizona. The field site allowed for controlled irrigation. Instrumentation for fluid sampling and water penetration were already in place. The porous loosely consolidated rocks at the site were not ideal for finding the effects of the attenuation mechanism we had identified in the lab, but for logistic and cost constraint reasons we chose to field test the idea at that site. Tiltmeters and seismometers were installed and operated nearly continuously for almost 3 years. The field was irrigated with water in the fall of 2003 and with water containing a biosurfactant in the fall of 2004. We have indications that the biosurfactant irrigation has had a notable effect on the tilt data.

  7. Identification and isolation of closed pore in porous rock using digital rock physics approach

    NASA Astrophysics Data System (ADS)

    Latief, Fourier Dzar Eljabbar

    2015-09-01

    The presence of closed pore in porous rock provide various effect with regard to its structural, elastic and flow properties. Physical based approach to measure porosity such as mercury porosimetry injection is unable to locate closed pore inside porous rock even though it is still possible to quantify the closed porosity. Digital data of porous rock in the form of three dimensional image can now be obtained by means of several methods such as micro-CT scan. Using the digital data, closed pore can be identified and isolated using digital rock physics approach. We first construct a synthetic three dimensional porous sample which consist of two simple side-to-side connected pore (cylinder and box shaped) and two spherical isolated pore which has closed porosity of 1.41 %. The digital image analysis which implemented in software CTAn (Bruker Micro-CT) still produce error of 0.04% which is very low. However, analysis using Lattice Boltzmann Method based simulation of fluid flow provide exact match to the closed porosity of the synthetic sample. Nevertheless, there are two disadvantages of this method, i.e., the simulation could take hours compared to the digital image analysis which only took several minutes and the limitation of numerical definition of zero velocity. Thus we apply both methods in order to overcome the drawbacks of each methods to analyze the digital sample of Fontainebleau sandstone. Using CTAn, we obtained the closed porosity of 0.02891845 % and using the LBM based fluid flow simulation of 0.028948346 %. The closed pore can then be isolated to further calculate the surface area. The result also confirmed that pore space of Fontainebleau sandstone is well connected.

  8. Digital material laboratory: Considerations on high-porous volcanic rock

    NASA Astrophysics Data System (ADS)

    Saenger, Erik H.; Stöckhert, Ferdinand; Duda, Mandy; Fischer, Laura; Osorno, Maria; Steeb, Holger

    2017-04-01

    Digital material methodology combines modern microscopic imaging with advanced numerical simulations of the physical properties of materials. One goal is to complement physical laboratory investigations for a deeper understanding of relevant physical processes. Large-scale numerical modeling of elastic wave propagation directly from the microstructure of the porous material is integral to this technology. The parallelized finite-difference-based Stokes solver is suitable for the calculation of effective hydraulic parameters for low and high porous materials. Reticulite is formed in very high Hawaiian fire fountaining events. Hawaiian fire fountaining eruptions produce columns or fountains of lava, which can last for a few hours to days. Reticulite was originally thought to have formed from further expanded hot scoria foam. However, some researchers believe reticulite forms from magma that formed vesicles instantly, which expanded rapidly and uniformly to produce the polyhedral vesicle walls. These walls then ruptured and cooled rapidly. The (open) honeycomb network of bubbles is held together by glassy threads and forms a structure with a porosity higher than 80%. The fragile rock sample is difficult to characterize with classical experimental methods and we show how to determine porosity, effective elastic properties and Darcy permeability by using digital material methodology. A technical challenge will be to image with the CT technique the thin skin between the glassy threads visible on the microscopy image. A numerical challenge will be determination of effective material properties and viscous fluid effects on wave propagation in such a high porous material.

  9. Method of determining interwell oil field fluid saturation distribution

    DOEpatents

    Donaldson, Erle C.; Sutterfield, F. Dexter

    1981-01-01

    A method of determining the oil and brine saturation distribution in an oil field by taking electrical current and potential measurements among a plurality of open-hole wells geometrically distributed throughout the oil field. Poisson's equation is utilized to develop fluid saturation distributions from the electrical current and potential measurement. Both signal generating equipment and chemical means are used to develop current flow among the several open-hole wells.

  10. Compaction bands in porous rocks: localization analysis using breakage mechanics

    NASA Astrophysics Data System (ADS)

    Das, Arghya; Nguyen, Giang; Einav, Itai

    2010-05-01

    It has been observed in fields and laboratory studies that compaction bands are formed within porous rocks and crushable granular materials (Mollema and Antonellini, 1996; Wong et al., 2001). These localization zones are oriented at high angles to the compressive maximum principal stress direction. Grain crushing and pore collapse are the integral parts of the compaction band formation; the lower porosity and increased tortuosity within such bands tend to reduce their permeability compared to the outer rock mass. Compaction bands may thereafter act as flow barriers, which can hamper the extraction or injection of fluid into the rocks. The study of compaction bands is therefore not only interesting from a geological viewpoint but has great economic importance to the extraction of oil or natural gas in the industry. In this paper, we study the formation of pure compaction bands (i.e. purely perpendicular to the principal stress direction) or shear-enhanced compaction bands (i.e. with angles close to the perpendicular) in high-porosity rocks using both numerical and analytical methods. A model based on the breakage mechanics theory (Einav, 2007a, b) is employed for the present analysis. The main aspect of this theory is that it enables to take into account the effect that changes in grain size distribution has on the constitutive stress-strain behaviour of granular materials at the microscopic level due to grain crushing. This microscopic phenomenon of grain crushing is explicitly linked with a macroscopic internal variable, called Breakage, so that the evolving grain size distribution can be continuously monitored at macro scale during the process of deformation. Through the inclusion of an appropriate parameter the model is also able to capture the effects of pore collapse on the macroscopic response. Its possession of few physically identifiable parameters is another important feature which minimises the effort of their recalibration, since those become less

  11. Changes in geophysical properties caused by fluid injection into porous rocks: analytical models: Geophysical changes in porous rocks

    DOE PAGES

    Pride, Steven R.; Berryman, James G.; Commer, Michael; ...

    2016-08-30

    Analytical models are provided that describe how the elastic compliance, electrical conductivity, and fluid-flow permeability of rocks depend on stress and fluid pressure. In order to explain published laboratory data on how seismic velocities and electrical conductivity vary in sandstones and granites, the models require a population of cracks to be present in a possibly porous host phase. The central objective is to obtain a consistent mean-field analytical model that shows how each modeled rock property depends on the nature of the crack population. We describe the crack populations by a crack density, a probability distribution for the crack aperturesmore » and radii, and the averaged orientation of the cracks. The possibly anisotropic nature of the elasticity, conductivity, and permeability tensors is allowed for; however, only the isotropic limit is used when comparing to laboratory data. For the transport properties of conductivity and permeability, the percolation effect of the crack population linking up to form a connected path across a sample is modeled. But, this effect is important only in crystalline rock where the host phase has very small conductivity and permeability. In general, the importance of the crack population to the transport properties increases as the host phase becomes less conductive and less permeable.« less

  12. Changes in geophysical properties caused by fluid injection into porous rocks: analytical models: Geophysical changes in porous rocks

    SciTech Connect

    Pride, Steven R.; Berryman, James G.; Commer, Michael; Nakagawa, Seiji; Newman, Gregory A.; Vasco, Donald W.

    2016-08-30

    Analytical models are provided that describe how the elastic compliance, electrical conductivity, and fluid-flow permeability of rocks depend on stress and fluid pressure. In order to explain published laboratory data on how seismic velocities and electrical conductivity vary in sandstones and granites, the models require a population of cracks to be present in a possibly porous host phase. The central objective is to obtain a consistent mean-field analytical model that shows how each modeled rock property depends on the nature of the crack population. We describe the crack populations by a crack density, a probability distribution for the crack apertures and radii, and the averaged orientation of the cracks. The possibly anisotropic nature of the elasticity, conductivity, and permeability tensors is allowed for; however, only the isotropic limit is used when comparing to laboratory data. For the transport properties of conductivity and permeability, the percolation effect of the crack population linking up to form a connected path across a sample is modeled. But, this effect is important only in crystalline rock where the host phase has very small conductivity and permeability. In general, the importance of the crack population to the transport properties increases as the host phase becomes less conductive and less permeable.

  13. Variational Principles for Dynamics of Linear Elastic Fluid-Saturated Soils.

    DTIC Science & Technology

    1985-07-01

    Include S cuty Clawfication, Variational Principl s 61102F 2307 C1 for Dynamics of Linear Elastic Fluid-Saturated Soils I _ II 12. PERSONALAUTHOR(S) Ranbir...RD-At75 92 VARIATIONAL PRINCIPLES FOR DYNAMICS OF LINEAR ELASTIC t/l FLUID-SATURATED SOI (U) OHIO STATE UNIV RESEARCH FOUNDATION COLUMBUS R S SANDHU...Sa* distribution unlimited. VARIATIONAL PRINCIPLES FOR DYNAMICS OF LINEAR ELASTIC FLUID-SATURATED SOILS 7 . Ranbir S. Sandhu and S. J. Hong L

  14. Intense fracturation induced by mineral growth in porous rocks

    NASA Astrophysics Data System (ADS)

    Renard, F.; Noiriel, C.; Gratier, J.-P.; Doan, M.-L.

    2009-04-01

    When minerals precipitate in the pores of a rock, they may exert a force that depends on the supersaturation of the fluid; this is the so-called force of crystallization. This process happens in a wide range of geological systems, e.g. vein formation in deep crust, frost heave in soils, and salt damage in cultural heritage monuments. Sometimes, the force of crystallization is so large that it leads to a permanent damage and fracturation of the porous medium. Here, we have studied this process experimentally and imaged in 3D how an intense fracture pattern may emerge from purely chemical processes. Core samples of limestone (22% porosity) and sandstones (19% porosity) were left for one month in contact with an aqueous solution saturated with sodium chloride in an autoclave, at 40°C, under a normal stress in the range 0.2-0.3 MPa. The fluid was allowed to rise in the core samples by capillary forces, up to a height where evaporation occurred. The samples were left in a rubber jacket with the same height as the capillary fringe, allowing therefore an accurate control of the region of water evaporation and salt precipitation. The uniaxial deformation of the samples was measured using high resolution displacement sensors. After the experiments we have imaged the samples in three dimensions, using laboratory computed X-ray tomography, allowing therefore imaging the intensity and localization of the damage, as well as the regions of salt precipitation. During the initial fluid capillary rise, the deformation measurements indicate a small shortening of the samples (~5 micrometers), and then an increase of the samples' height (50-100 micrometers) during salt precipitation. Two kinds of damage could be observed in tomography. Firstly, small rock fragments were pealed from the sample surface. Secondly, and more interestingly, a radial fracture network developed, by nucleation of microcracks at the interface where evaporation occurred, and propagation to the free surface. Two

  15. 3D geometry and hydrodynamic modifications in fractured and porous rock samples through chemical alterations.

    NASA Astrophysics Data System (ADS)

    Noiriel, C. N.

    2011-12-01

    Fractured and porous rocks are the principal path for water flow and potential contamination. Modification of fracture topology and transmissivity by reactive fluids is an important and complex geological process. In carbonate rocks, fractures and porous media properties may change quickly and strongly due to natural processes (e.g. karstification, salt intrusion) or anthropogenic practice (e.g. CO2 geological sequestration). Recent application of X-ray micro-tomography to the Earth Sciences, which allows the visualization of 3D objects with a micrometre resolution, has considerably increased experimental capability by giving access to a 4D spatio-temporal vision (3D geometry + time) of the physical-chemical processes within the rocks. New information is now accessible, which provides a better understanding of the processes and allows the numerical models to be better constrained. I will present the application of X-ray micro-tomography to study changes of petrophysical properties (e.g. porosity, permeability, mineral surface area, etc.) of fractured and porous rocks in response to fluid-rock interactions (dissolution and precipitation). Experimental results will be discussed in regard to numerical modelling of flow and transport. Keywords: X-ray micro-tomography, fracture, porous media, dissolution, precipitation, carbon dioxide sequestration, limestone, reactive surface, geochemical modelling,

  16. Viscoelastic Waves Simulation in a Blocky Medium with Fluid-Saturated Interlayers Using High-Performance Computing

    NASA Astrophysics Data System (ADS)

    Sadovskii, Vladimir; Sadovskaya, Oxana

    2017-04-01

    A thermodynamically consistent approach to the description of linear and nonlinear wave processes in a blocky medium, which consists of a large number of elastic blocks interacting with each other via pliant interlayers, is proposed. The mechanical properties of interlayers are defined by means of the rheological schemes of different levels of complexity. Elastic interaction between the blocks is considered in the framework of the linear elasticity theory [1]. The effects of viscoelastic shear in the interblock interlayers are taken into consideration using the Pointing-Thomson rheological scheme. The model of an elastic porous material is used in the interlayers, where the pores collapse if an abrupt compressive stress is applied. On the basis of the Biot equations for a fluid-saturated porous medium, a new mathematical model of a blocky medium is worked out, in which the interlayers provide a convective fluid motion due to the external perturbations. The collapse of pores is modeled within the generalized rheological approach, wherein the mechanical properties of a material are simulated using four rheological elements. Three of them are the traditional elastic, viscous and plastic elements, the fourth element is the so-called rigid contact [2], which is used to describe the behavior of materials with different resistance to tension and compression. Thermodynamic consistency of the equations in interlayers with the equations in blocks guarantees fulfillment of the energy conservation law for a blocky medium in a whole, i.e. kinetic and potential energy of the system is the sum of kinetic and potential energies of the blocks and interlayers. As a result of discretization of the equations of the model, robust computational algorithm is constructed, that is stable because of the thermodynamic consistency of the finite difference equations at a discrete level. The splitting method by the spatial variables and the Godunov gap decay scheme are used in the blocks, the

  17. Pressure and fluid saturation prediction in a multicomponent reservoir, using combined seismic and electromagnetic imaging

    SciTech Connect

    Hoversten, G.M.; Gritto, Roland; Washbourne, John; Daley, Tom

    2002-06-10

    This paper presents a method for combining seismic and electromagnetic measurements to predict changes in water saturation, pressure, and CO{sub 2} gas/oil ratio in a reservoir undergoing CO{sub 2} flood. Crosswell seismic and electromagnetic data sets taken before and during CO{sub 2} flooding of an oil reservoir are inverted to produce crosswell images of the change in compressional velocity, shear velocity, and electrical conductivity during a CO{sub 2} injection pilot study. A rock properties model is developed using measured log porosity, fluid saturations, pressure, temperature, bulk density, sonic velocity, and electrical conductivity. The parameters of the rock properties model are found by an L1-norm simplex minimization of predicted and observed differences in compressional velocity and density. A separate minimization, using Archie's law, provides parameters for modeling the relations between water saturation, porosity, and the electrical conductivity. The rock-properties model is used to generate relationships between changes in geophysical parameters and changes in reservoir parameters. Electrical conductivity changes are directly mapped to changes in water saturation; estimated changes in water saturation are used along with the observed changes in shear wave velocity to predict changes in reservoir pressure. The estimation of the spatial extent and amount of CO{sub 2} relies on first removing the effects of the water saturation and pressure changes from the observed compressional velocity changes, producing a residual compressional velocity change. This velocity change is then interpreted in terms of increases in the CO{sub 2}/oil ratio. Resulting images of the CO{sub 2}/oil ratio show CO{sub 2}-rich zones that are well correlated to the location of injection perforations, with the size of these zones also correlating to the amount of injected CO{sub 2}. The images produced by this process are better correlated to the location and amount of injected

  18. A Computer Program for Consolidation and Dynamic Response Analysis of Fluid-Saturated Media.

    DTIC Science & Technology

    1983-06-01

    Codes Avail and/or Geotechnical Engineering Report No. 14 Dist I Special The Ohio State University Research Foundation 1314 Kinnear Road, Columbus, Ohio...CONSOLIDATION AND DYNAMIC RESPONSE ANALYSIS OF FLUID-SATURATED MEDIA Ranbir S. Sandhu, B. Aboustit, S. J. Hong and M. S. Hiremath Department of Civil Engineering ...RESPONSE ANALYSIS OF FLUID-SATURATED MEDIA By Ranbir S. Sandhu, B. Aboustit, S. J. Hong and M. S. Hiremath Department of Civil Engineering June 1984 Acce

  19. Shape matters: pore geometry and orientation influences the strength and stiffness of porous rocks

    NASA Astrophysics Data System (ADS)

    Griffiths, Luke; Heap, Michael; Xu, Tao; Chen, Chong-Feng; Baud, Patrick

    2017-04-01

    The geometry of voids in porous rock fall between two end-members: very low aspect ratio (the ratio of the minor to the major semi-axis) microcracks and perfectly spherical pores with an aspect ratio of unity. Although the effect of these end-member geometries on the mechanical behaviour of porous rock has received considerable attention, our understanding of the influence of voids with an intermediate aspect ratio is much less robust. Here we perform two-dimensional numerical simulations (Rock Failure Process Analysis, RFPA2D) to better understand the influence of pore aspect ratio (from 0.2 to 1.0) and the angle between the pore major axis and the applied stress (from 0 to 90°) on the mechanical behaviour of porous rock. Our numerical simulations show that, for a fixed aspect ratio (0.5) the uniaxial compressive strength and Young's modulus of porous rock can be reduced by a factor of 2.4 and 1.3, respectively, as the angle between the major axis of the elliptical pores and the applied stress is rotated from 0 to 90°. This weakening effect is accentuated at higher porosities. The influence of pore aspect ratio (which we vary from 0.2 to 1.0) on strength and Young's modulus depends on the pore angle. At low angles ( 0-10°) an increase in aspect ratio reduces the strength and Young's modulus. At higher angles ( 40-90°), however, strength and Young's modulus increase as aspect ratio is increased. At intermediate angles ( 20-30°), strength and Young's modulus first increase and then decrease as pore aspect ratio approaches unity. We find that the analytical solutions for the stress and Young's modulus at the boundary of a single elliptical pore are in excellent agreement with our numerical simulations. The results of our numerical modelling are also in agreement with recent experimental data for porous basalt, but fail to capture the strength anisotropy observed in experiments on sandstone. The alignment of grains or platy minerals such as clays may play an

  20. XFEM modeling of hydraulic fracture in porous rocks with natural fractures

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Liu, ZhanLi; Zeng, QingLei; Gao, Yue; Zhuang, Zhuo

    2017-08-01

    Hydraulic fracture (HF) in porous rocks is a complex multi-physics coupling process which involves fluid flow, diffusion and solid deformation. In this paper, the extended finite element method (XFEM) coupling with Biot theory is developed to study the HF in permeable rocks with natural fractures (NFs). In the recent XFEM based computational HF models, the fluid flow in fractures and interstitials of the porous media are mostly solved separately, which brings difficulties in dealing with complex fracture morphology. In our new model the fluid flow is solved in a unified framework by considering the fractures as a kind of special porous media and introducing Poiseuille-type flow inside them instead of Darcy-type flow. The most advantage is that it is very convenient to deal with fluid flow inside the complex fracture network, which is important in shale gas extraction. The weak formulation for the new coupled model is derived based on virtual work principle, which includes the XFEM formulation for multiple fractures and fractures intersection in porous media and finite element formulation for the unified fluid flow. Then the plane strain Kristianovic-Geertsma-de Klerk (KGD) model and the fluid flow inside the fracture network are simulated to validate the accuracy and applicability of this method. The numerical results show that large injection rate, low rock permeability and isotropic in-situ stresses tend to lead to a more uniform and productive fracture network.

  1. Research of Radionuclides Migrating in Porous Media Allowing for the "Solution-Rock" Interaction

    NASA Astrophysics Data System (ADS)

    Drozhko, E.; Aleksakhin, A. I.; Samsanova, L.; Kotchergina, N.; Zinin, A.

    2001-12-01

    Industrial solutions from the surface storage of liquid radioactive waste in Lake Karachay, near the Mayak Production Association in Russia, enter groundwaters through the reservoir loamy bed and have formed a contaminated groundwater plume. In order to predict radionuclide migration with the groundwater flow in porous unconsolidated rocks and to assess the protective mechanism of the natural environment, it is necessary to allow for the "solution-rock" physical and chemical interaction described by the distribution factor (Kd). In order to study radionuclide distribution in porous media, a numerical model was developed which models stontium-90 migration in a uniform unit of loams typical for the Karachay Lake bed. For the migration to be calculated, the results of the in situ and laboratory reasearch on strontium-90 sorption and desorption were used in the code, as well as strontium-90 dependance on sodium nitrate concentration in the solution. The code uses various models of the "solution-rock" interaction, taking into account both sorption/desorption and diffusion processes. Numerical research of strontium-90 migration resulted in data on strontium-90 distribution in solid and liquid phases of the porous loam unit over different time periods. Various models of the "solution-rock" interaction affecting strontium-90 migration are demonstrated.

  2. The internal magnetic field distribution, and single exponential magnetic resonance free induction decay, in rocks.

    PubMed

    Chen, Quan; Marble, Andrew E; Colpitts, Bruce G; Balcom, Bruce J

    2005-08-01

    When fluid saturated porous media are subjected to an applied uniform magnetic field, an internal magnetic field, inside the pore space, is induced due to magnetic susceptibility differences between the pore-filling fluid and the solid matrix. The microscopic distribution of the internal magnetic field, and its gradients, was simulated based on the thin-section pore structure of a sedimentary rock. The simulation results were verified experimentally. We show that the 'decay due to diffusion in internal field' magnetic resonance technique may be applied to measure the pore size distribution in partially saturated porous media. For the first time, we have observed that the internal magnetic field and its gradients in porous rocks have a Lorentzian distribution, with an average gradient value of zero. The Lorentzian distribution of internal magnetic field arises from the large susceptibility contrast and an intrinsic disordered pore structure in these porous media. We confirm that the single exponential magnetic resonance free induction decay commonly observed in fluid saturated porous media arises from a Lorentzian internal field distribution. A linear relationship between the magnetic resonance linewidth, and the product of the susceptibility difference in the porous media and the applied magnetic field, is observed through simulation and experiment.

  3. Unsaturated hydraulic properties of porous sedimentary rocks explained by mercury porosimetry

    NASA Astrophysics Data System (ADS)

    Clementina Caputo, Maria; Turturro, Celeste; Gerke, Horst H.

    2016-04-01

    The understanding of hydraulic properties is essential in the modeling of flow and solute transport including contaminants through the vadose zone, which consists of the soil as well as of the underlying porous sediments or rocks. The aim of this work is to study the relationships between unsaturated hydraulic properties of porous rocks and their pore size distribution. For this purpose, two different lithotypes belonging to Calcarenite di Gravina Formation, a Plio-Pleistocene sedimentary rock of marine origin, were investigated. The two lithotypes differ mainly in texture and came from two distinct quarry districts, Canosa di Puglia (C) and Massafra (M) in southern Italy, respectively. This relatively porous rock formation (porosities range between 43% for C and 41% for M) often constitutes a thick layer of vadose zone in several places of Mediterranean basin. The water retention curves (WRCs) and the unsaturated hydraulic conductivity functions were determined using four different experimental methods that cover the full range from low to high water contents: the WP4 psychrometer test, the Wind's evaporation method, the Stackman's method and the Quasi-steady centrifuge method. Pore size estimation by means of mercury intrusion porosimetry (MIP) was performed. WRCs were compared with the pore size distributions to understand the influence of fabric, in terms of texture and porosity, features of pores and pore size distribution on the hydraulic behavior of rocks. The preliminary results show that the pore size distributions obtained by MIP do not cover the entire pore size range of the investigated Calcarenite. In fact, some pores in the rock samples of both lithotypes were larger than the maximum size that could be investigated by MIP. This implies that for explaining the unsaturated hydraulic properties over the full moisture range MIP results need to be combined with results obtained by other methods such as image analysis and SEM.

  4. An Integrated Tensorial Approach for Quantifying Porous, Fractured Rocks

    NASA Astrophysics Data System (ADS)

    Healy, David; Rizzo, Roberto; Harland, Sophie; Farrell, Natalie; Browning, John; Meredith, Phil; Mitchell, Tom; Bubeck, Alodie; Walker, Richard

    2017-04-01

    The patterns of fractures in deformed rocks are rarely uniform or random. Fracture orientations, sizes, shapes and spatial distributions often exhibit some kind of order. In detail, there may be relationships among the different fracture attributes e.g. small fractures dominated by one orientation, and larger fractures by another. These relationships are important because the mechanical (e.g. strength, anisotropy) and transport (e.g. fluids, heat) properties of rock depend on these fracture patterns and fracture attributes. Based on previously published work (Oda, Cowin, Sayers & Kachanov) this presentation describes an integrated tensorial approach to quantifying fracture networks and predicting the key properties of fractured rock: permeability and elasticity (and in turn, seismic velocities). Each of these properties can be represented as tensors, and these entities capture the essential 'directionality', or anisotropy of the property. In structural geology, we are familiar with using tensors for stress and strain, where these concepts incorporate volume averaging of many forces (in the case of the stress tensor), or many displacements (for the strain tensor), to produce more tractable and more computationally efficient quantities. It is conceptually attractive to formulate both the structure (the fracture network) and the structure-dependent properties (permeability, elasticity) in a consistent way with tensors of 2nd and 4th rank, as appropriate. Examples are provided to highlight the interdependence of the property tensors with the geometry of the fracture network. The fabric tensor (or orientation tensor of Scheidegger, Woodcock) describes the orientation distribution of fractures in the network. The crack tensor combines the fabric tensor (orientation distribution) with information about the fracture density and fracture size distribution. Changes to the fracture network, manifested in the values of the fabric and crack tensors, translate into changes in

  5. Computational rock physics: Transport properties in porous media and applications

    NASA Astrophysics Data System (ADS)

    Keehm, Youngseuk

    Earth sciences is undergoing a gradual but massive shift from descriptions of the earth and earth systems, toward process modeling, simulation, and process visualization. This shift is very challenging because the underlying physical and chemical processes are often nonlinear and coupled, and take place in strongly heterogeneous systems. An example is two-phase fluid flow in rocks: a nonlinear, coupled, and time-dependent problem in complex microgeometry. To understand these complex processes, the knowledge of the underlying pore-scale processes is essential. This work focuses on building transport process simulators in realistic pore microstructures. These pore-scale simulators will be modules of a computational rock physics framework with future acoustic, elastic, electrical and NMR property simulators. This computational environment can significantly complement the physical laboratory, with several distinct advantages: rigorous prediction of physical properties, interrelations among the physical properties, and simulation of dynamic problems with multiple physical responses. This dissertation is initiative for the computational rock physics framework---a quantitative model for coupled, nonlinear, transient and complex behavior of earth systems. A rigorous pore-scale simulation requires three important traits: reliability, efficiency, and the ability to handle complex microgeometry. We implemented single-phase and two-phase flow simulators using the Lattice-Boltzmann algorithm, since it handles very complex pore geometries without idealization of the pore space. The single-phase flow simulator successfully replicates fluid flow in a digital representation of real sandstone, and predicts permeability very accurately. Furthermore, two applications using the single-phase flow simulator are proposed: a permeability estimation technique from thin sections, and diagenesis modeling with fluid flow. These two applications show the potential applicability of this robust

  6. Structural controls on anomalous transport in fractured porous rock

    NASA Astrophysics Data System (ADS)

    Edery, Yaniv; Geiger, Sebastian; Berkowitz, Brian

    2016-07-01

    Anomalous transport is ubiquitous in a wide range of disordered systems, notably in fractured porous formations. We quantitatively identify the structural controls on anomalous tracer transport in a model of a real fractured geological formation that was mapped in an outcrop. The transport, determined by a continuum scale mathematical model, is characterized by breakthrough curves (BTCs) that document anomalous (or "non-Fickian") transport, which is accounted for by a power law distribution of local transition times ψ>(t>) within the framework of a continuous time random walk (CTRW). We show that the determination of ψ>(t>) is related to fractures aligned approximately with the macroscopic direction of flow. We establish the dominant role of fracture alignment and assess the statistics of these fractures by determining a concentration-visitation weighted residence time histogram. We then convert the histogram to a probability density function (pdf) that coincides with the CTRW ψ>(t>) and hence anomalous transport. We show that the permeability of the geological formation hosting the fracture network has a limited effect on the anomalous nature of the transport; rather, it is the fractures transverse to the flow direction that play the major role in forming the long BTC tail associated with anomalous transport. This is a remarkable result, given the complexity of the flow field statistics as captured by concentration transitions.

  7. An Elastic Stress-Strain Relationship for Porous Rock Under Anisotropic Stress Conditions

    NASA Astrophysics Data System (ADS)

    Zhao, Yu; Liu, Hui-Hai

    2012-05-01

    A stress-strain relationship within porous rock under anisotropic stress conditions is required for modeling coupled hydromechanical processes associated with a number of practical applications. In this study, a three-dimensional stress-strain relationship is proposed for porous rock under elastic and anisotropic stress conditions. This relationship is a macroscopic-scale approximation that uses a natural-strain-based Hooke's law to describe deformation within a fraction of pores and an engineering-strain-based Hooke's law to describe deformation within the other part. This new relationship is evaluated using data from a number of uniaxial and triaxial tests published in the literature. Based on this new stress-strain relationship, we also develop constitutive relationships among stress, strain, and related stress-dependent hydraulic/mechanical properties (such as compressibility, shear modulus, and porosity). These relationships are demonstrated to be consistent with experimental observations.

  8. Forced oscillation measurements of seismic attenuation in fluid saturated sandstone

    NASA Astrophysics Data System (ADS)

    Subramaniyan, Shankar; Quintal, Beatriz; Saenger, Erik H.

    2017-02-01

    Adopting the method of forced oscillation, attenuation was studied in Fontainebleau sandstone (porosity 10%, permeability 10 mD) at seismic frequencies (1-100 Hz). Confining pressures of 5, 10, and 15 MPa were chosen to simulate reservoir conditions. First, the strain effect on attenuation was investigated in the dry sample for 11 different strains across the range 1 × 10-6-8 × 10-6, at the confining pressure of 5 MPa. The comparison showed that a strain of at least 5 × 10-6 is necessary to obtain a good signal to noise ratio. These results also indicate that nonlinear effects are absent for strains up to 8 × 10-6. For all the confining pressures, attenuation in the dry rock was low, while partial (90%) and full (100%) saturation with water yielded a higher magnitude and frequency dependence of attenuation. The observed high and frequency dependent attenuation was interpreted as being caused by squirt flow.

  9. Porous grain model and equivalent elastic medium approach for predicting effective elastic properties of sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Ruiz, Franklin J.

    This dissertation presents the results of using different inclusion and granular effective medium models and poroelasticity to predict the elastic properties of rocks with complex microstructures. Effective medium models account for the microstructure and texture of rocks, and can be used to predict the type of rock and microstructure from seismic velocities and densities. We introduce the elastic equivalency approach, using the differential effective medium model, to predict the effective elastic moduli of rocks and attenuation. We introduce the porous grain concept and develop rock physics models for rocks with microporosity. We exploit the porous grain concept to describe a variety of arrangements of uncemented and cemented grains with different degrees of hydraulic connectivity in the pore space. We first investigate the accuracy of the differential effective medium and self-consistent estimations of elastic properties of complex rock matrix using composites as analogs. We test whether the differential effective-medium (DEM) and self-consistent (SC) models can accurately estimate the elastic moduli of a complex rock matrix and compare the results with the average of upper and lower Hashin-Shtrikman bounds. We find that when the material microstructure is consistent with DEM, this model is more accurate than both SC and the bound-average method for a variety of inclusion aspect ratios, concentrations, and modulus contrasts. Based on these results, we next pose a question: can a theoretical inclusion model, specifically, the differential effective-medium model (DEM), be used to match experimental velocity data in rocks that are not necessarily made of inclusions (such as elastics)? We first approach this question by using empirical velocity-porosity equations as proxies for data. By finding a DEM inclusion aspect ratio (AR) to match these equations, we find that the required range of AR is remarkably narrow. Moreover, a constant AR of about 0.13 can be used to

  10. Unified pipe network method for simulation of water flow in fractured porous rock

    NASA Astrophysics Data System (ADS)

    Ren, Feng; Ma, Guowei; Wang, Yang; Li, Tuo; Zhu, Hehua

    2017-04-01

    Rock masses are often conceptualized as dual-permeability media containing fractures or fracture networks with high permeability and porous matrix that is less permeable. In order to overcome the difficulties in simulating fluid flow in a highly discontinuous dual-permeability medium, an effective unified pipe network method is developed, which discretizes the dual-permeability rock mass into a virtual pipe network system. It includes fracture pipe networks and matrix pipe networks. They are constructed separately based on equivalent flow models in a representative area or volume by taking the advantage of the orthogonality of the mesh partition. Numerical examples of fluid flow in 2-D and 3-D domain including porous media and fractured porous media are presented to demonstrate the accuracy, robustness, and effectiveness of the proposed unified pipe network method. Results show that the developed method has good performance even with highly distorted mesh. Water recharge into the fractured rock mass with complex fracture network is studied. It has been found in this case that the effect of aperture change on the water recharge rate is more significant in the early stage compared to the fracture density change.

  11. A broadband laboratory study of the seismic properties of cracked and fluid-saturated synthetic glass media

    NASA Astrophysics Data System (ADS)

    Li, Yang; David, Emmanuel; Nakagawa, Seiji; Kneafsey, Timothy; Schmitt, Douglas; Jackson, Ian

    2017-04-01

    In order to better understand the frequency dependence or dispersion of seismic-wave speeds and associated strain-energy dissipation in cracked and fluid-saturated crustal rocks, we have conducted a broadband laboratory study of synthetic glass media. The glass materials were prepared either from dense soda-lime-silica glass rod or by sintering glass beads of similar chemical composition. Along with sub-equant pores contributing either 2 or 5% porosity for the sintered-bead specimens, quantifiable densities of cracks, generally of very low aspect ratio, were introduced by controlled thermal cracking. Permeability was measured under selected conditions of confining and pore pressure either by transient decay with argon pore fluid or with the steady-flow method and water pore fluid. The water permeability of the cracked glass-rod specimen decreased strongly with increasing differential pressure Pd to 10-18 m2 near 10 MPa. Further increase of differential pressure towards 100 MPa resulted in modest reductions of permeability to specimen-specific values in the range (0.5 - 2) × 10-19 m2. The characteristic frequencies for the draining of cylindrical specimens of such low permeability are estimated to be < 10 mHz, so that undrained conditions can be expected even at the 10-300 mHz frequencies of the forced-oscillation tests. The same or similarly prepared glass specimens were mechanically tested with sub-Hz forced-oscillation methods, a kHz-frequency resonant bar technique, and MHz-frequency ultrasonic wave propagation, before and after thermal cracking. The cracked specimens were successively measured under dry, argon- (or nitrogen-) saturated and water-saturated conditions. The shear and Young's moduli measured on the cracked materials typically increase strongly with increasing differential pressure below a threshold of 30 MPa beyond which the pressure sensitivity becomes substantially milder. This behaviour is quantitatively interpreted in terms of pressure

  12. On the Relationship between Stress and Elastic Strain for Porous and Fractured Rock

    SciTech Connect

    Liu, Hui-Hai; Rutqvist, Jonny; Berryman, James G.

    2008-02-25

    Modeling the mechanical deformations of porous and fractured rocks requires a stress-strain relationship. Experience with inherently heterogeneous earth materials suggests that different varieties of Hook's law should be applied within regions of the rock having significantly different stress-strain behavior, e.g., such as solid phase and various void geometries. We apply this idea by dividing a rock body conceptually into two distinct parts. The natural strain (volume change divided by rock volume at the current stress state), rather than the engineering strain (volume change divided by the unstressed rock volume), should be used in Hooke's law for accurate modeling of the elastic deformation of that part of the pore volume subject to a relatively large degree of relative deformation (i.e., cracks or fractures). This approach permits the derivation of constitutive relations between stress and a variety of mechanical and/or hydraulic rock properties. We show that the theoretical predictions of this method are generally consistent with empirical expressions (from field data) and also laboratory rock experimental data.

  13. The influence of pore geometry and orientation on the strength and stiffness of porous rock

    NASA Astrophysics Data System (ADS)

    Griffiths, Luke; Heap, Michael J.; Xu, Tao; Chen, Chong-feng; Baud, Patrick

    2017-03-01

    The geometry of voids in porous rock falls between two end-members: very low aspect ratio (the ratio of the minor to the major axis) microcracks and perfectly spherical pores with an aspect ratio of unity. Although the effect of these end-member geometries on the mechanical behaviour of porous rock has received considerable attention, our understanding of the influence of voids with an intermediate aspect ratio is much less robust. Here we perform two-dimensional numerical simulations (Rock Failure Process Analysis, RFPA2D) to better understand the influence of pore aspect ratio (from 0.2 to 1.0) and the angle between the pore major axis and the applied stress (from 0 to 90°) on the mechanical behaviour of porous rock under uniaxial compression. Our numerical simulations show that, for a fixed aspect ratio (0.5) the uniaxial compressive strength and Young's modulus of porous rock can be reduced by a factor of ∼2.4 and ∼1.3, respectively, as the angle between the major axis of the elliptical pores and the applied stress is rotated from 0 to 90°. The influence of pore aspect ratio on strength and Young's modulus depends on the pore angle. At low angles (∼0-10°) an increase in aspect ratio reduces the strength and Young's modulus. At higher angles (∼40-90°), however, strength and Young's modulus increase as aspect ratio is increased. At intermediate angles (∼20-30°), strength and Young's modulus first increase and then decrease as pore aspect ratio approaches unity. These simulations also highlight that the influence of pore angle on compressive strength and Young's modulus decreases as the pore aspect ratio approaches unity. We find that the analytical solution for the stress concentration around a single elliptical pore, and its contribution to elasticity, are in excellent qualitative agreement with our numerical simulations. The results of our numerical modelling are also in agreement with recent experimental data for porous basalt, but fail to

  14. Earth science: role of fO2 on fluid saturation in oceanic basalt.

    PubMed

    Scaillet, Bruno; Pichavant, Michel

    2004-07-29

    Assessing the conditions under which magmas become fluid-saturated has important bearings on the geochemical modelling of magmas because volatile exsolution may profoundly alter the behaviour of certain trace elements that are strongly partitioned in the coexisting fluid. Saal et al. report primitive melt inclusions from dredged oceanic basalts of the Siqueiros transform fault, from which they derive volatile abundances of the depleted mantle, based on the demonstration that magmas are not fluid-saturated at their eruption depth and so preserve the mantle signature in terms of their volatile contents. However, in their analysis, Saal et al. consider only fluid-melt equilibria, and do not take into account the homogeneous equilibria between fluid species, which, as we show here, may lead to a significant underestimation of the pressure depth of fluid saturation.

  15. Adsorption and chemical precipitation of lead and zinc from contaminated solutions in porous rocks: Possible application in environmental protection

    NASA Astrophysics Data System (ADS)

    Németh, Gabriella; Mlinárik, Lilla; Török, Ákos

    2016-10-01

    Natural porous rocks, like limestone and rhyolite tuff are able to reduce heavy metal pollution by adsorbing or precipitating them from heavy metal containing solutions due to the favourable physical and chemical properties of these rocks. In our experiment, two porous rocks, a porous limestone and rhyolite tuff were used. Petrophysical parameters namely apparent density, real density, capillary water absorption, ultrasonic pulse velocity, total porosity and open porosity of the two porous rocks were determined in water-saturated and dried conditions. Powdered rock samples and cylindrical specimens were placed in lead-nitrate and zinc-sulphate solutions (initial concentration: 1000 ppm) and the amount of lead (II) and zinc (II) ions were identified by titration (chelatometry) of the residual solution. According to the experiments, powdered rocks and rock specimens of limestone and rhyolite tuff reduced the lead (II) and zinc (II) ion concentrations in aqueous solution. The results were cross-checked by ICP-MS. Heavy metal removal capacity was relatively high, 92-99% in each case. The treated powdered rocks and rock specimens were also studied by scanning electron microscope (SEM-EDS) and new heavy metal precipitates were identified. According to the tests result, it could be confirmed that these types of lithologies are capable of removing heavy metals and can be used in environmental protection technologies in a form of permeable reactive barrier.

  16. Joint Inversion of Marine Seismic and CSEM Data for Fluid Saturation Prediction

    NASA Astrophysics Data System (ADS)

    Hoversten, G. M.; Gasperikova, E.; Chen, J.; Newman, G.

    2005-12-01

    demanding approaches is underway there is interest in an approach that can be deployed quickly. One method for combining seismic and CSEM data is a relatively straightforward extension of what is currently done using seismic data alone (Bachrach and Dutta, 2004). The use of Bayesian inversion, which couples a rock-physics model with estimates of geophysical parameters, can be extended to include electrical conductivity. In this paper, we demonstrate the use of AVA inversion to estimate acoustic- (Vp), shear-velocity (Vs), and density (ρ) coupled with 3D CSEM (Newman and Boggs, 2004) inversion to estimate electrical conductivity (σ) in a Bayesian inverse for reservoir fluid saturations and φ. This approach is compared to the formal joint inversion described by Hoversten et al. (2004, 2005). The two-stage process has the advantage that it can be done using existing industry software, with only the addition of the electromagnetic inversions to estimate electrical conductivity. The estimated water saturation and porosity compare well to both log data and those derived from a formal joint inversion of marine AVA and electromagnetic data. However, the two-stage estimates of oil and gas saturation do not compare favorably to those obtained using a formal joint inversion of both data sets simultaneously.

  17. Porous flow of liquid water in Enceladus rock core driven by heterogeneous tidal heating

    NASA Astrophysics Data System (ADS)

    Choblet, Gael; Tobie, Gabriel; Behounkova, Marie; Cadek, Ondrej

    2016-10-01

    Surface heat flux estimates in excess of 15 GW (e.g. Howett et al., 2016) raise the question of the origin of Enceladus' heat production. While strong heating by tidal dissipation is probably the only viable source, whether the maximum production occurs in the outer ice shell or, deeper, in the ocean or in the rock core, is however unclear. While the analysis of measurements by the Cassini mission (gravity and topography data, observed libration), seems to favor an extremely thin shell at Enceladus South Pole (a few kms only, cf. Thomas et al., 2016, Cadek et al., 2016), the distribution of heat sources remains a major issue in the light of the evolutionary trend that led to this present-day physical state of the moon.Here, we build up on a recent evaluation of tidal deformation in a porous rock core saturated with liquid water indicating that, owing to its unconsolidated state, plausible core rheologies could lead to significant heat production there (typically 20 GW, Tobie et al., in prep.). We describe porous flow in a 3D spherical model following the work of Travis and Schubert (2015). Compaction of the rock matrix is neglected. Water characteristics (density and viscosity), and the bulk thermal conductivity of the porous core are temperature-dependent and the effect of non-water compounds can be considered. Tidal heating is introduced as a heterogeneous heat source with a pattern inferred from numerical models of the tidal response. Our analysis focuses particularly on the heat flux pattern at the ocean/core interface where water is advected in/out of the porous medium.

  18. The Melt Transition in Mature, Fluid-Saturated Gouge

    NASA Astrophysics Data System (ADS)

    Rempel, A. W.

    2006-12-01

    Mechanisms that link the evolution of fault strength and temperature during earthquakes have been studied extensively, with accumulating constraints from theoretical, field and laboratory investigations promoting increased confidence in our understanding of the dominant physical interactions. In mature fault zones that have accommodated many large earthquakes and are characterized by gouge layers that greatly exceed the thickness of the ~ mm-scale "principal slip surfaces" in which shear is localized, the thermal pressurization of pore fluids is expected to be particularly important for reducing the fault strength and limiting the extent of shear heating. Nevertheless, for sufficiently large slip distances and reasonable estimates of hydraulic transport properties and other controlling variables, the predicted temperature increases are sometimes able to reach the onset of melting, particularly at mid to lower seismogenic depths (e.g. 10km). Reported field observations of quenched glassy melt products, known as pseudotachylytes, are much more common on young faults, particularly where slip is initiated between coherent rock surfaces, rather than in exhumed mature fault zones, where thermal pressurization is likely to be more important and macroscopic melting appears to be rare. Those pseudotachylyte layers that are recovered from mature fault zones display a range of thicknesses and crystal contents, which indicate that significant shear heating continued long after the onset of melting, with work performed against the viscous resistance of a partially molten slurry. Models that describe the transition to melting in a finite shear zone that is initially saturated with pore fluids are presented with two main conceptual challenges: 1. the energy input for frictional heating is generally assumed to be proportional to the effective stress, which vanishes when macroscopic melt layers are produced and thermodynamic considerations require that the melt pressure balance the

  19. Creep of porous rocks and measurements of elastic wave velocities under different hydrous conditions

    NASA Astrophysics Data System (ADS)

    Eslami, J.; Grgic, D.; Hoxha, D.

    2009-04-01

    The long-term mechanical behavior of rocks is of prime importance for many geological hazards (e.g., landslides, rock falls, and volcanoes) as well as for the stability of man-made structures (underground mines, road cuts, and open pits). In some shallow environments, rocks exist in partially saturated conditions which can evolve with time according to variations in the relative humidity hr of the atmosphere (e.g., natural slopes, open cut excavations). In underground mines, rocks are also partially saturated because of artificial ventilation. These variations in liquid saturation may have a large impact on mechanical behavior since they imply variations in capillary pressure and, depending on the porosity and on the shape of the porous network, variations in the effective stresses. Therefore, knowledge of static fatigue under saturated and partially saturated conditions is important for estimating the long-term stability of such rock structures. Many studies have already shown that time-dependent weakening is much more important for a saturated rock than for a dry one and that the time to failure may decrease by several orders of magnitude for saturated rocks as compared to dry rocks. In addition, the weakening effect of water is more significant in long-term experiments than in short-term ones (instantaneous loading). A physical explanation for these results may be the enhancement of subcritical crack growth by stress corrosion at crack tips which is often considered to be the main cause of time-dependent behavior of rocks. The failure of brittle rocks during compression tests is preceded by the formation, growth, and coalescence of microcracks. Elastic wave velocities are reduced due to the presence of open microcraks and fractures and may be used to monitor the progressive damage of rocks. The specific experimental setup available in our lab allows the simultaneous measurement of five velocities (with different polarizations and directions) and two directions

  20. New method for measuring compressibility and poroelasticity coefficients in porous and permeable rocks

    NASA Astrophysics Data System (ADS)

    Pimienta, Lucas; Fortin, Jérôme; Guéguen, Yves

    2017-04-01

    Over the last decades, a large understanding has been gained on the elastic properties of rocks. Rocks are, however, porous materials, which properties depend on both response of the bulk material and of the pores. Because in that case both the applied external pressure and the fluid pressure play a role, different poroelasticity coefficients exist. While theoretical relations exist, measuring precisely those different coefficients remains an experimental challenge. Accounting for the different experimental complexities, a new methodology is designed that allows attaining accurately a large set of compressibility and poroelasticity coefficients in porous and permeable rocks. This new method relies on the use of forced confining or pore fluid pressure oscillations. In total, seven independent coefficients have been measured using three different boundary conditions. Because the usual theories predict only four independent coefficients, this overdetermined set of data can be checked against existing thermodynamic relations. Measurements have been performed on a Bentheim sandstone under, water- and glycerine-saturated conditions for different values of confining and pore fluid pressure. Consistently with the poroelasticity theory, the effect of the fluid bulk modulus is observed under undrained conditions but not under drained ones. Using thermodynamic relations, (i) the unjacketed, quartz, and skeleton (Zimmerman's relation) bulk moduli fit, (ii) the drained and undrained properties fit, and (iii) it is directly inferred from the measurements that the pore skeleton compressibility Cϕ is expected to be constant with pressure and to be exceedingly near the bulk skeleton Cs and mineral Cm compressibility coefficients.

  1. Numerical model of halite precipitation in porous sedimentary rocks adjacent to salt diapirs

    NASA Astrophysics Data System (ADS)

    Li, Shiyuan; Wang, Yan; Zhao, Pengyun

    2017-10-01

    Salt diapirs are commonly seen in the North Sea. Below the Zechstein Group exist possibly overpressured salt-anhydrite formations. One explanation as to the salt precipitation in areas with salt diapirs is that salt cementation is thermally driven and occurs strongly in places adjacent to salt diapirs. This paper assumes that the sealing effect of the cap rock above the salt formations is compromised and overpressured fluids, carrying dissolved minerals such as anhydrite (CaSO4) and salt mineral components (NaCl of halite), flow into the porous sedimentary layers above the salt formations. Additionally, a salt-diapir-like structure is assumed to be at one side of the model. The numerical flow and heat transport simulator SHEMAT-Suite was developed and applied to calculating the concentrations of species, and dissolution and precipitation amounts. Results show that the overpressured salt-anhydrite formations have higher pressure heads and the species elements sodium and chlorite are transported into porous sediment rocks through water influx (saturated brine). Halite can precipitate as brine with sodium and chlorite ions flows to the cooler environment. Salt cementation of reservoir rocks leads to decreasing porosity and permeability near salt domes, and cementation of reservoir formations decreases with growing distance to the salt diapir. The proposed approach in this paper can also be used to evaluate precipitation relevant to scaling problems in geothermal engineering.

  2. Use of ``rock-typing`` to characterize carbonate reservoir heterogeneity. Final report

    SciTech Connect

    Ikwuakor, K.C.

    1994-03-01

    The objective of the project was to apply techniques of ``rock-typing`` and quantitative formation evaluation to borehole measurements in order to identify reservoir and non-reservoir rock-types and their properties within the ``C`` zone of the Ordovician Red River carbonates in the northeast Montana and northwest North Dakota areas of the Williston Basin. Rock-typing discriminates rock units according to their pore-size distribution. Formation evaluation estimates porosities and pore fluid saturation. Rock-types were discriminated using crossplots involving three rock-typing criteria: (1) linear relationship between bulk density and porosity, (2) linear relationship between acoustic interval transit-time and porosity, and (3) linear relationship between acoustic interval transit-time and bulk density. Each rock-type was quantitatively characterized by the slopes and intercepts established for different crossplots involving the above variables, as well as porosities and fluid saturations associated with the rock-types. All the existing production was confirmed through quantitative formation evaluation. Highly porous dolomites and anhydritic dolomites contribute most of the production, and constitute the best reservoir rock-types. The results of this study can be applied in field development and in-fill drilling. Potential targets would be areas of porosity pinchouts and those areas where highly porous zones are downdip from non-porous and tight dolomites. Such areas are abundant. In order to model reservoirs for enhanced oil recovery (EOR) operations, a more localized (e.g. field scale) study, expanded to involve other rock-typing criteria, is necessary.

  3. From the surface to the deep critical zone: Linking soil carbon, fluid saturation and weathering rate

    NASA Astrophysics Data System (ADS)

    Druhan, Jennifer; Lawrence, Corey; Oster, Jessica; Rempe, Daniella; Dietrich, William

    2017-04-01

    Shallow soils from a wide range of ecosystems demonstrate a clear and consistent relationship between effective fluid saturation and the rate at which organic carbon is converted to CO2. While the underlying mechanisms contributing to this dependence are diverse, a consistent pattern of maximum CO2 production at intermediate soil moisture supports a generalized functional relationship, which may be incorporated into a quantitative reactive transport framework. A key result of this model development is a prediction of the extent to which the inorganic carbon content of water in biologically active soils varies as a function of hydrologic parameters (i.e. moisture content and residence time), and in turn influences weathering reactions. Deeper in the CZ, the consistency of this relationship and the influence of hydrologically - regulated CO2 production on the rates of water - rock interaction are largely unknown. Here, we use a novel reactive transport model incorporating this functional relationship to consider how variations in the reactive potential of water entering the vadose zone influences subsurface weathering rates. We leverage two examples of variably saturated natural systems to consider (1) CO2 production and associated weathering potential regulated by seasonal hydrologic shifts and (2) the preservation of soil carbon signatures in the deep CZ over millennial timescales. First, at the Eel River CZ Observatory in Northern California, USA, a novel Vadose Zone Monitoring System (VMS) installed in a 14 - 20 m thick unsaturated section offers an unprecedented view into the physical, chemical and biological behavior of the depth profile separating soils from groundwater. Based on soil moisture, gas and fluid phase samples, we demonstrate a predictive relationship between seasonal hydrologic variations and the location and magnitude of geochemical weathering rates. Second, an environmental monitoring project in the Blue Springs Cave, Sparta, TN, USA, provides

  4. Advective-diffusive mass transfer in fractured porous media with variable rock matrix block size.

    PubMed

    Sharifi Haddad, Amin; Hassanzadeh, Hassan; Abedi, Jalal

    2012-05-15

    Traditional dual porosity models do not take into account the effect of matrix block size distribution on the mass transfer between matrix and fracture. In this study, we introduce the matrix block size distributions into an advective-diffusive solute transport model of a divergent radial system to evaluate the mass transfer shape factor, which is considered as a first-order exchange coefficient between the fracture and matrix. The results obtained lead to a better understanding of the advective-diffusive mass transport in fractured porous media by identifying two early and late time periods of mass transfer. Results show that fractured rock matrix block size distribution has a great impact on mass transfer during early time period. In addition, two dimensionless shape factors are obtained for the late time, which depend on the injection flow rate and the distance of the rock matrix from the injection point. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Fluid Transport in Porous Rocks. I. EPI Studies and a Stochastic Model of Flow

    NASA Astrophysics Data System (ADS)

    Mansfield, P.; Issa, B.

    The velocity of water flowing through a Bentheimer sandstone core has been measured by NMR-imaging techniques. The localized pixel values of velocity indicate a random distribution centered around the mean value corresponding to Darcy's law. When the same flow state is repeated, the velocity map changes but the general characteristics of the velocity distribution remain unchanged. The random nature of the irreproducibility of the flow maps has led us to propose a stochastic theory of flow in porous rocks. The theory leads to a Gaussian velocity distribution which approximates well to the data. Also predicted is a linear relationship between flow variance and mean fluid flow through the rock, the Mansfield-Issa equation, originally proposed as an empirical relationship.

  6. Water saturation effects on elastic wave attenuation in porous rocks with aligned fractures

    NASA Astrophysics Data System (ADS)

    Amalokwu, Kelvin; Best, Angus I.; Sothcott, Jeremy; Chapman, Mark; Minshull, Tim; Li, Xiang-Yang

    2014-05-01

    Elastic wave attenuation anisotropy in porous rocks with aligned fractures is of interest to seismic remote sensing of the Earth's structure and to hydrocarbon reservoir characterization in particular. We investigated the effect of partial water saturation on attenuation in fractured rocks in the laboratory by conducting ultrasonic pulse-echo measurements on synthetic, silica-cemented, sandstones with aligned penny-shaped voids (fracture density of 0.0298 ± 0.0077), chosen to simulate the effect of natural fractures in the Earth according to theoretical models. Our results show, for the first time, contrasting variations in the attenuation (Q-1) of P and S waves with water saturation in samples with and without fractures. The observed Qs/Qp ratios are indicative of saturation state and the presence or absence of fractures, offering an important new possibility for remote fluid detection and characterization.

  7. A visco-poroelastic damage model for modelling compaction and brittle failure of porous rocks

    NASA Astrophysics Data System (ADS)

    Jacquey, Antoine B.; Cacace, Mauro; Blöcher, Guido; Milsch, Harald; Scheck-Wenderoth, Magdalena

    2016-04-01

    Hydraulic stimulation of geothermal wells is often used to increase heat extraction from deep geothermal reservoirs. Initiation and propagation of fractures due to pore pressure build-up increase the effective permeability of the porous medium. Understanding the processes controlling the initiation of fractures, the evolution of their geometries and the hydro-mechanical impact on transport properties of the porous medium is therefore of great interest for geothermal energy production. In this contribution, we will present a thermodynamically consistent visco-poroelastic damage model which can deal with the multi-scale and multi-physics nature of the physical processes occurring during deformation of a porous rock. Deformation of a porous medium is crucially influenced by the changes in the effective stress. Considering a strain-formulated yield cap and the compaction-dilation transition, three different regimes can be identified: quasi-elastic deformation, cataclastic compaction with microcracking (damage accumulation) and macroscopic brittle failure with dilation. The governing equations for deformation, damage accumulation/healing and fluid flow have been implemented in a fully-coupled finite-element-method based framework (MOOSE). The MOOSE framework provides a powerful and flexible platform to solve multiphysics problems implicitly and in a tightly coupled manner on unstructured meshes which is of interest for such non-linear context. To validate and illustrate the model, simulations of the deformation behaviour of cylindrical porous Bentheimer sandstone samples under different confining pressures are compared to experiments. The first experiment under low confining pressure leads to shear failure, the second for high confining pressure leads to cataclastic compaction and the third one with intermediate confining pressure correspond to a transitional regime between the two firsts. Finally, we will demonstrate that this approach can also be used at the field

  8. Experimental Measurements Of Seismic Wave Speeds And Attenuation In CO2 Saturated Porous Rocks

    NASA Astrophysics Data System (ADS)

    Njiekak, G.; Yam, H.; Kofman, R. S.; Chowdhury, M.; Schmitt, D. R.

    2011-12-01

    Due to the sensitivity of seismic waves to pore fluid contents, time lapse seismology is regarded as a promising monitoring method for geological CO2 sequestration projects and is employed in all industrial scale projects (Sleipner, Weyburn, In Salah). Therefore, understanding the effect of CO2 as a pore fluid on the overall rock seismic response is critical, and it is particularly interesting as CO2 can be in gas, liquid, or supercritical phases even at the relatively modest pore pressures and temperatures in the uppermost kilometer of the earth's crust. To address this issue, ultrasonic P- and S-wave pulse transmission experiments were carried out on fully CO2 saturated samples of a synthetic porous ceramic, Berea and Fontainebleau sandstones, and carbonates under a variety of temperatures and pressures representative of conditions expected in volcanic edifices and geological sequestration projects. The synthetic sample was chosen because of its lack of microcracks, which can complicate the acoustic behavior of real rocks. Although this sample is extremely porous (58%) and is not reflective of real reservoir rocks, its large porosity allows the overall rock behavior to be more susceptible to the changes in the physical properties of the pore fluid; this could provide an extreme end member understanding on the rock physics involved with CO2 as the pore fluid. Laboratory results show waveform variations (velocity, amplitude, attenuation) in response to CO2's varying phase state. For the ceramic rod, CO2 phase changes (gas to liquid and gas to supercritical fluid) are marked by a drop in velocities of 4-5% likely due to the increased density of the liquid or the supercritical fluid relative to the gas. Wave attenuation increases with pore pressure and with frequency. The measured elastic wave velocities showed good agreement with Biot's model in this highly porous sample. The real sandstones, in contrast, display more complicated behaviour at the point of the phase

  9. A damage mechanics approach for quantifying stress changes due to brittle failure of porous rocks

    NASA Astrophysics Data System (ADS)

    Jacquey, Antoine B.; Cacace, Mauro; Blöcher, Guido; Milsch, Harald; Scheck-Wenderoth, Magdalena

    2016-04-01

    Natural fault zones or man-made injection or production of fluid impact the regional stress distribution in Earth's crust and can be responsible for localized stress discontinuities. Understanding the processes controlling fracturing of the porous rocks and mechanical behaviour of fault zones is therefore of interest for several applications including geothermal energy production. In this contribution, we will present a thermodynamically consistent visco-poroelastic damage model which can deal with the multi-scale and multi-physics nature of the physical processes controlling the deformation of porous rocks during and after brittle failure. Deformation of a porous medium is crucially influenced by the changes in the effective stress. Considering a strain-formulated yield cap and the compaction-dilation transition, three different regimes can be identified: quasi-elastic deformation, cataclastic compaction with microcracking (damage accumulation) and macroscopic brittle failure with dilation. The governing equations for deformation, damage accumulation/healing and fluid flow have been implemented in a fully-coupled finite-element-method based framework (MOOSE). The MOOSE framework provides a powerful and flexible platform to solve multiphysics problems implicitly and in a tightly coupled manner on unstructured meshes which is of interest for such non-linear context. To illustrate the model, simulation of a compaction experiment of a sandstone leading to shear failure will be presented which allows to quantify the stress drop accompanying the failure. Finally, we will demonstrate that this approach can also be used at the field scale to simulate hydraulic fracturing and assess the resulting changes in the stress field.

  10. On the micromechanics of slip events in sheared, fluid-saturated fault gouge

    NASA Astrophysics Data System (ADS)

    Dorostkar, Omid; Guyer, Robert A.; Johnson, Paul A.; Marone, Chris; Carmeliet, Jan

    2017-06-01

    We used a three-dimensional discrete element method coupled with computational fluid dynamics to study the poromechanical properties of dry and fluid-saturated granular fault gouge. The granular layer was sheared under dry conditions to establish a steady state condition of stick-slip dynamic failure, and then fluid was introduced to study its effect on subsequent failure events. The fluid-saturated case showed increased stick-slip recurrence time and larger slip events compared to the dry case. Particle motion induces fluid flow with local pressure variation, which in turn leads to high particle kinetic energy during slip due to increased drag forces from fluid on particles. The presence of fluid during the stick phase of loading promotes a more stable configuration evidenced by higher particle coordination number. Our coupled fluid-particle simulations provide grain-scale information that improves understanding of slip instabilities and illuminates details of phenomenological, macroscale observations.

  11. 3-D Numerical Simulation of Hydrostatic Tests of Porous Rocks Using Adapted Constitutive Model

    NASA Astrophysics Data System (ADS)

    Chemenda, A. I.; Daniel, M.

    2014-12-01

    The high complexity and poor knowledge of the constitutive properties of porous rocks are principal obstacles for the modeling of their deformation. Normally, the constitutive lows are to be derived from the experimental data (nominal strains and stresses). They are known, however, to be sensitive to the mechanical instabilities within the rock specimen and the boundary (notably friction) conditions at its ends. To elucidate the impact of these conditions on the measured mechanical response we use 3-D finite-difference simulations of experimental tests. Modeling of hydrostatic tests was chosen because it does not typically involve deformation instabilities. The ends of the cylindrical 'rock sample' are in contact with the 'steel' elastic platens through the frictional interfaces. The whole system is subjected to a normal stress Pc applied to the external model surface. A new constitutive model of porous rocks with the cap-type yield function is used. This function is quadratic in the mean stress σm and depends on the inelastic strain γp in a way to generate strain softening at small σm and strain-hardening at high σm. The corresponding material parameters are defined from the experimental data and have clear interpretation in terms of the geometry of the yield surface. The constitutive model with this yield function and the Drucker-Prager plastic potential has been implemented in 3-D dynamic explicit code Flac3D. The results of an extensive set of numerical simulations at different model parameters will be presented. They show, in particular, that the shape of the 'numerical' hydrostats is very similar to that obtained from the experimental tests and that it is practically insensitive to the interface friction. On the other hand, the stress and strain fields within the specimen dramatically depend on this parameter. The inelastic deformation at the specimen's ends starts well before reaching the grain crushing pressure P* and evolves heterogeneously with Pc

  12. Initial conditions or emergence; what determines dissolution patterns in heterogeneous porous rocks?

    NASA Astrophysics Data System (ADS)

    Szymczak, Piotr; Upadhyay, Virat; Ladd, Anthony

    2016-04-01

    Dissolution of fractured or porous rocks is often accompanied by the formation of highly localized flow paths. Dissolution, in general, does not proceed uniformly, as it is influenced both by the heterogeneities in the rock matrix and by the instabilities associated with the positive feedback loops between the flow, dispersion, and chemical reactions. As a result, distinct channels or "wormholes" develop within the rocks in which both the flow and dissolution focus. In this communication, we aim to investigate how these emerging flow paths are influenced by the initial local inhomogeneities of the porosity field. Our results indicate a surprising insensitivity of the evolving dissolution patterns and flow rates to the amplitude and correlation length characterizing the inhomogeneities. At long times wormhole competition overwhelms the initial variations in aperture distribution, resulting in a universal relation between the separation of the wormholes and their length. This hierarchy of scales even persists in the presence of relatively large inhomogeneities (vugs), which focus the flow at the beginning of the dissolution process, but - if the sample is large enough - with time tend to be overwhelmed by the spontaneous growth of instabilities. A natural consequence of wormhole competition is that the separation between growing wormholes corresponds roughly to their length, something that is borne out by field observations.

  13. Field and numerical determinations of pneumatic flow parameters of unsaturated fractured porous rocks on various scales

    NASA Astrophysics Data System (ADS)

    Guillon, S.; Vu, M. T.; Pili, E.; Adler, P. M.

    2013-05-01

    Air permeability is measured in the fractured crystalline rocks of the Roselend Natural Laboratory (France). Single-hole pneumatic injection tests as well as differential barometric pressure monitoring are conducted on scales ranging from 1 to 50 m, in both shallow and deep boreholes, as well as in an isolated 60 m3 chamber at 55 m depth. The field experiments are interpreted using numerical simulations in equivalent homogeneous porous media with their real 3-D geometry in order to estimate pneumatic parameters. For pneumatic injection tests, steady-state data first allow to estimate air permeability. Then, pressure recovery after a pneumatic injection test allows to estimate the air-filled porosity. Comparison between the various studied cases clarifies the influence of the boundary conditions on the accuracy of the often used 1-D estimate of air permeability. It also shows that permeabilities correlate slightly with fracture density. In the chamber, a 1 order-of-magnitude difference is found between the air permeabilities obtained from pneumatic injection tests and from differential barometric pressure monitoring. This discrepancy is interpreted as a scale effect resulting from the approximation of the heterogeneous fractured rock by a homogeneous numerical model. The difference between the rock volumes investigated by pneumatic injection tests and by differential barometric pressure monitoring may also play a role. No clear dependence of air permeability on saturation has been found so far.

  14. Measuring the DC electrokinetic coupling coefficient of porous rock samples in the laboratory : a new apparatus

    NASA Astrophysics Data System (ADS)

    Walker, E.; Tardif, E.; Glover, P. W.; Ruel, J.; Hadjigeorgiou, J.

    2009-12-01

    Electro-kinetic properties of rocks allow the generation of an electric potential by the flow of an aqueous fluid through a porous media. The electrical potential is called the streaming potential, and the streaming potential coupling coefficient Cs is the ratio of the generated electric potential to the pressure difference that causes the fluid flow. The streaming potential coupling coefficient for rocks is described in the steady-state regime by the well known Helmholtz-Smoluchowski equation, and is supported by a relatively small body of experimental data. However, the electrokinetic coupling coefficient measurement is important for the further development of different area of expertise such as reservoir prospection and monitoring, volcano and earthquake monitoring and the underground sequestration of CO2. We have designed, constructed and tested a new experimental cell that is capable of measuring the DC streaming potential of consolidated and unconsolidated porous media. The new cell is made from stainless steel, perspex and other engineering polymers. Cylindrical samples of 25.4 mm can be placed in a deformable rubber sleeve and subjected to a radial confining pressure of compressed nitrogen up to 4.5 MPa. Actively degassed aqueous fluids can be flowed by an Agilent 1200 series binary pump (2 to 10 mL/min). A maximum input fluid pressure of 2.5 MPa can be applied, with a maximum exit pressure of 1 MPa to ensure sample saturation is stable and to reduce gas bubbles. The pressures each side of the sample are measured by high stability pressure transducers (Omega PX302-300GV), previously calibrated by a high precision differential pressure transducer Endress and Hauser Deltabar S PMD75. The streaming potentials are measured with Harvard Apparatus LF-1 and LF-2 Ag/AgCl non-polarising miniature electrodes. An axial pressure is applied (1 to 6.5 MPa) to counteract the radial pressure and provide additional axial load with a hydraulic piston. It is our intention to

  15. Measuring the DC electrokinetic coupling coefficient of porous rock samples in the laboratory : A new apparatus

    NASA Astrophysics Data System (ADS)

    Walker, Emilie; Tardif, Eric; Glover, Paul; Ruel, Jean; Lalande, Guillaume; Hadjigeorgiou, John

    2010-05-01

    Electro-kinetic properties of rocks allow the generation of an electric potential by the flow of an aqueous fluid through a porous media. The electrical potential is called the streaming potential, and the streaming potential coupling coefficient is the ratio of the generated electric potential to the pressure difference that causes the fluid flow. The streaming potential coupling coefficient for rocks is described in the steady-state regime by the well known Helmholtz-Smoluchowski equation, and is supported by a relatively small body of experimental data. However, the electrokinetic coupling coefficient measurement is important for the further development of different area of expertise such as reservoir prospection and monitoring, volcano and earthquake monitoring and the underground sequestration of carbon dioxide. We have designed, constructed and tested a new experimental cell that is capable of measuring the DC streaming potential of consolidated and unconsolidated porous media. The new cell is made from stainless steel, perspex and other engineering polymers. Cylindrical samples of 25.4 mm can be placed in a deformable rubber sleeve and subjected to a radial confining pressure of compressed nitrogen up to 4.5 MPa. Actively degassed aqueous fluids can be flowed by an Agilent 1200 series binary pump (2 to 10 mL/min). A maximum input fluid pressure of 2.5 MPa can be applied, with a maximum exit pressure of 1 MPa to ensure sample saturation is stable and to reduce gas bubbles. The pressures each side of the sample are measured by high stability pressure transducers (Omega PX302-300GV), previously calibrated by a high precision differential pressure transducer Endress and Hauser Deltabar S PMD75. The streaming potentials are measured with Harvard Apparatus LF-1 and LF-2 Ag/AgCl non-polarising miniature electrodes. An axial pressure is applied (1 to 6.5 MPa) to counteract the radial pressure and provide additional axial load with a hydraulic piston. It is our

  16. Effect of fracture network geometry on density-driven flow in fractured porous rock

    NASA Astrophysics Data System (ADS)

    Vujevic, Katharina; Graf, Thomas

    2013-04-01

    Density-driven flow can be a highly efficient transport mechanism in hydrogeological systems, especially if head gradients as a driving force for groundwater movement are absent. Unstable density layering may lead to variable-density, free-convective flow. Convection cells may form whose number and shape depends on the prevailing concentration and temperature gradients. The presence of open fractures may complicate the free convective flow pattern because fractures represent preferential pathways where water flow velocities can be considerably larger than in the rock matrix. Therefore, the purpose of this study is to provide insight into the structural properties of fracture networks that determine flow and transport patterns and to make a statement on the applicability of the equivalent porous medium approach (EPM). We systematically study free convective flow in continuous, discontinuous, orthogonal and inclined fracture networks embedded in a low-permeability rock matrix. Layer stability and convection patterns for different fracture networks are compared to each other and to an unfractured base case representing an EPM. We examine rates of solute transport by monitoring the mass flux at the solute source and relate it to the critical structural properties of the fracture networks. Simulations are performed using the numerical variable-density groundwater flow and transport model HydroGeoSphere. Fractures are represented as discrete fractures, whose geometric properties are explicitly defined. Fracture permeability is calculated using the cubic law. Results show that for free convective flow, the EPM approach is not able to reliably represent a fractured porous medium if fracture permeability is more than 5 orders of magnitude larger than matrix permeability. Nonetheless the EPM approach can be a reasonable approximation if the fracture network (i) evenly covers the simulated rock, (ii) is of high fracture density, (iii) is well-connected, (iv) contains

  17. Selection of Bacteria with Favorable Transport Properties Through Porous Rock for the Application of Microbial-Enhanced Oil Recovery

    PubMed Central

    Jang, Long-Kuan; Chang, Philip W.; Findley, John E.; Yen, Teh Fu

    1983-01-01

    This paper presents a bench-scale study on the transport in highly permeable porous rock of three bacterial species—Bacillus subtilis, Pseudomonas putida, and Clostridium acetobutylicum—potentially applicable in microbial-enhanced oil recovery processes. The transport of cells during the injection of bacterial suspension and nutrient medium was simulated by a deep bed filtration model. Deep bed filtration coefficients and the maximum capacity of cells in porous rock were measured. Low to intermediate (∼106/ml) injection concentrations of cellular suspensions are recommended because plugging of inlet surface is less likely to occur. In addition to their resistance to adverse environments, spores of clostridia are strongly recommended for use in microbial-enhanced oil recovery processes since they are easiest among the species tested to push through porous rock. After injection, further transport of bacteria during incubation can occur by growth and mobility through the stagnant nutrient medium which fills the porous rock. We have developed an apparatus to study the migration of bacteria through a Berea sandstone core containing nutrient medium. PMID:16346414

  18. Quasistatic Shock Waves: A Mechanism for Nonuniform Compaction in Porous Rock

    SciTech Connect

    OLSSON,WILLIAM A.

    2000-09-08

    Recent studies have observed compaction zones pass through porous rock under axisymmetric compression. An initially thin, compacted layer appears at the yield point of the stress-strain curve and then grows by thickening in the direction of maximum compression at constant stress. Strain localization theory has been applied to compaction to explain the formation of these features. This paper describes the growth of the compaction zones, that is, the propagation of their boundaries, in terms of shock wave analysis. The ratio of the applied shortening rate to the velocity of the boundary is related to the porosity change across the boundary. Certain features of the stress-strain curve are explained by the model.

  19. Use of GPU Computing to Study Coupled Deformation and Fluid Flow in Porous Rocks

    NASA Astrophysics Data System (ADS)

    Räss, Ludovic; Omlin, Samuel; Simon, Nina; Podladchikov, Yuri

    2015-04-01

    Actual challenges in computational geodynamics put high requirements for the development of new coupled models. These need to solve accurate physics, on high resolution and in reasonable computation time. Multi-scale problems such as deformation of porous rocks triggered by fluid flow require both high temporal and spatial resolution. The resulting preferential flow paths involve complex physics and a strong coupling between deformation and fluid flow processes. Shortcuts such as sequential or iterative coupling of two existing solvers will not be sufficient in these difficult cases to localize the deformation and flow. We base our numerical implementation on the physically and thermodynamically consistent mathematical model for fluid flow in porous rocks, taking nonlinear stress dependent visco-elasto-plastic rheology into account. The effective permeability used for the Darcy flow is obtained through the nonlinear Karman-Cozeny relation. The model is not restricted by the lithostatic stress assumption, allowing for background stress regime as it occurs in natural conditions. We have developed a fully three-dimensional numerical application based on an iterative finite difference scheme. The application is written in C-CUDA, is enabled for GPU accelerators and is parallelized with MPI to run on multi-GPU clusters. The parallelization on a rectangular grid is straightforward (at each iteration, the boundaries of the local problem are updated by the neighboring processes) and requires no MPI global operations, only MPI point-to-point communication between neighboring processes. This parallelization method should allow by construction for linear weak scaling on any number of processors. Our linearly scaling numerical application predicts the formation of dynamically evolving fluid pathways. These supercomuting applications are vital for resolving actual challenging high-resolution three-dimensional models.

  20. Using Resin-Based 3D Printing to Build Geometrically Accurate Proxies of Porous Sedimentary Rocks.

    PubMed

    Ishutov, Sergey; Hasiuk, Franciszek J; Jobe, Dawn; Agar, Susan

    2017-09-28

    Three-dimensional (3D) printing is capable of transforming intricate digital models into tangible objects, allowing geoscientists to replicate the geometry of 3D pore networks of sedimentary rocks. We provide a refined method for building scalable pore-network models ("proxies") using stereolithography 3D printing that can be used in repeated flow experiments (e.g., core flooding, permeametry, porosimetry). Typically, this workflow involves two steps, model design and 3D printing. In this study, we explore how the addition of post-processing and validation can reduce uncertainty in the 3D-printed proxy accuracy (difference of proxy geometry from the digital model). Post-processing is a multi-step cleaning of porous proxies involving pressurized ethanol flushing and oven drying. Proxies are validated by: (1) helium porosimetry and (2) digital measurements of porosity from thin-section images of 3D-printed proxies. 3D printer resolution was determined by measuring the smallest open channel in 3D-printed "gap test" wafers. This resolution (400 µm) was insufficient to build porosity of Fontainebleau sandstone (∼13%) from computed tomography data at the sample's natural scale, so proxies were printed at 15-, 23-, and 30-fold magnifications to validate the workflow. Helium porosities of the 3D-printed proxies differed from digital calculations by up to 7% points. Results improved after pressurized flushing with ethanol (e.g., porosity difference reduced to ∼1% point), though uncertainties remain regarding the nature of sub-micron "artifact" pores imparted by the 3D printing process. This study shows the benefits of including post-processing and validation in any workflow to produce porous rock proxies. © 2017, National Ground Water Association.

  1. Modeling of Viscoelastic Properties of Porous Rocks Saturated with Viscous Fluid at Seismic Frequencies at the Core Scale

    NASA Astrophysics Data System (ADS)

    Schmitt, D. R.; Wang, Z.; Wang, F.; Wang, R.

    2015-12-01

    Currently the moduli and velocities of rocks at seismic frequencies are usually measured by the strain-stress method in lab. However, such measurements require well-designed equipment and skilled technicians, which greatly hinders the experimental investigation on the elastic and visco-elastic properties of rocks at seismic frequencies. We attempt to model the dynamic moduli of porous rocks saturated with viscous fluid at seismic frequencies on core scale using the strain-stress method, aiming to provide a complement to real core measurements in lab. First, we build 2D geometrical models containing the pore structure information of porous rocks based on the digital images (such as thin section, SEM, CT, etc.) of real rocks. Then we assume the rock frames are linearly elastic, and use the standard Maxwell spring-dash pot model to describe the visco-elastic properties of pore fluids. Boundary conditions are set according to the strain-stress method; and the displacement field is calculated using the finite element method (FEM). We numerically test the effects of fluid viscosity, frequency, and pore structure on the visco-elastic properties based on the calculation results. In our modeling, the viscosity of the pore fluid ranges from 103mPas to 109mPas; and the frequency varies from 5Hz to 500Hz. The preliminary results indicate that the saturated rock behaves stiffer and shows larger phase lag between stress and strain when the viscosity of the pore fluid and (or) the frequency increase.

  2. Detection of moving capillary front in porous rocks using X-ray and ultrasonic methods

    NASA Astrophysics Data System (ADS)

    David, Christian; Bertauld, Delphine; Dautriat, Jérémie; Sarout, Joël; Menéndez, Beatriz; Nabawy, Bassem

    2015-07-01

    Several methods are compared for the detection of moving capillary fronts in spontaneous imbibition experiments where water invades dry porous rocks. These methods are: (i) the continuous monitoring of the mass increase during imbibition, (ii) the imaging of the water front motion using X-ray CT scanning, (iii) the use of ultrasonic measurements allowing the detection of velocity, amplitude and spectral content of the propagating elastic waves, and (iv) the combined use of X-ray CT scanning and ultrasonic monitoring. It is shown that the properties of capillary fronts depend on the heterogeneity of the rocks, and that the information derived from each method on the dynamics of capillary motion can be significantly different. One important result from the direct comparison of the moving capillary front position and the P wave attributes is that the wave amplitude is strongly impacted before the capillary front reaches the sensors, in contrast with the velocity change which is concomitant with the fluid front arrival in the sensors plane.

  3. Numerical simulation of salt cementation in the porous rocks adjacent to salt diapirs

    NASA Astrophysics Data System (ADS)

    Allstadt, Raphael; Li, Shiyuan; Marquart, Gabriele; Reuning, Lars; Niederau, Jan

    2015-04-01

    Porosity and permeability are among the most important petrophysical properties of reservoirs rocks in oil systems. Observations during exploration indicate that in the vicinity of salt domes the porosity of reservoir rocks is often reduced by halite cementation. In this study we present results of simulating the process of salt precipitation near salt diapirs by using a schematic model of a Zechstein diapir in the North Sea basin. The numerical simulation is based on solving the transport equations for heat, porous flow and dispersive and reactive chemical species. Chemical reaction and equilibrium is based on the PHREEQC computer code. In our model over-pressured brine is entering from below and is deflected towards the diapir due to an intermediate layer of low permeability. The high thermal conductivity of salt yields a lateral temperature gradient starting from the diapir. Due to this effect the simulated temperature profile shows lower temperatures close to the salt dome than in comparable depths further away. Caused by the temperature-controlled solubility of NaCl in the brine and supplied ions by the diapir, halite first precipitates near the salt diapir by cementing the pore spaces and thus reducing the porosity. Salt-precipitation in the simulation starts after 840 000 years and reduces the porosity from 10 % to 5.5 % after 19 Mill. years. The permanent influx of brine causes growth of the cementation area and the related reduction of porosity in the reservoir.

  4. Fluid Transport in Porous Rocks. II. Hydrodynamic Model of Flow and Intervoxel Coupling

    NASA Astrophysics Data System (ADS)

    Mansfield, P.; Issa, B.

    In a preceding paper [P. Mansfield and B. Issa, J. Magn. Reson. A122, 137-148 (1996)], a stochastic model of fluid flow in porous rocks based upon the experimental observation of water flow through a Bentheimer sandstone core was proposed. The flow maps were measured by NMR-imaging techniques. The stochastic theory led to a Gaussian velocity distribution with a mean value in accord with Darcy's law. Also predicted was a linear relationship between flow variance and mean fluid flow through rock, the Mansfield-Issa equation, originally proposed as an empirical relationship. In the present work a flow coupling mechanism between voxels is proposed. Examination of the flow coupling between isolated voxel pairs leads to a complementary explanation of the Gaussian velocity distribution, and also gives further details of the Mansfield-Issa equation. These details lead to a new expression for the connectivity, < C>, between voxels with an experimental value of < C> = 5.64 × 10 -9for Bentheimer sandstone.

  5. An H2O-CO2 mixed fluid saturation model compatible with rhyolite-MELTS

    NASA Astrophysics Data System (ADS)

    Ghiorso, Mark S.; Gualda, Guilherme A. R.

    2015-06-01

    A thermodynamic model for estimating the saturation conditions of H2O-CO2 mixed fluids in multicomponent silicate liquids is described. The model extends the capabilities of rhyolite-MELTS (Gualda et al. in J Petrol 53:875-890, 2012a) and augments the water saturation model in MELTS (Ghiorso and Sack in Contrib Mineral Petrol 119:197-212, 1995). The model is internally consistent with the fluid-phase thermodynamic model of Duan and Zhang (Geochim Cosmochim Acta 70:2311-2324, 2006). It may be used independently of rhyolite-MELTS to estimate intensive variables and fluid saturation conditions from glass inclusions trapped in phenocrysts. The model is calibrated from published experimental data on water and carbon dioxide solubility, and mixed fluid saturation in silicate liquids. The model is constructed on the assumption that water dissolves to form a hydroxyl melt species, and that carbon dioxide both a molecular species and a carbonate ion, the latter complexed with calcium. Excess enthalpy interaction terms in part compensate for these simplistic assumptions regarding speciation. The model is restricted to natural composition liquids over the pressure range 0-3 GPa. One characteristic of the model is that fluid saturation isobars at pressures greater than ~100 MPa always display a maximum in melt CO2 at nonzero H2O melt concentrations, regardless of bulk composition. This feature is universal and can be attributed to the dominance of hydroxyl speciation at low water concentrations. The model is applied to four examples. The first involves estimation of pressures from H2O-CO2-bearing glass inclusions found in quartz phenocrysts of the Bishop Tuff. The second illustrates H2O and CO2 partitioning between melt and fluid during fluid-saturated equilibrium and fractional crystallization of MORB. The third example demonstrates that the position of the quartz-feldspar cotectic surface is insensitive to melt CO2 contents, which facilitates geobarometry using phase

  6. Electrical spectroscopy of porous rocks: a review-I.Theoretical models

    NASA Astrophysics Data System (ADS)

    Chelidze, T. L.; Gueguen, Y.

    1999-04-01

    The complex dielectric permittivity epsilon* of porous water-bearing rocks in the frequency range from a few to hundreds of megahertz reveals several intensive relaxation effects and a non-trivial dependence on the water content. At high frequencies, f>10 MHz, both the real part of the complex dielectric permittivity epsilon' and the conductivity sigma of water-bearing rocks are correctly predicted by the Maxwell-Wagner-Bruggeman-Hanai (MWBH) theory of composite dielectrics. This theory takes into account only the bulk properties of components, their partial volumes and the configuration of particles. The theory ignores two important factors: the surface contribution to polarization and the effect of clustering of components. At frequencies f<10 MHz there are certain frequency domains which exhibit relaxation processes not predicted by MWBH theory. The characteristic times of these processes range from 10^- ^6 to 10 s. These relaxation effects are related to different surface polarization processes which are, in order of increasing water content, (i) orientational polarization of bound water, (ii) polarization of liquid films or pockets, producing a polarization catastrophe effect, (iii) polarization of rough fractal surfaces, (iv) polarization of the `closed' electrical double layer (EDL), when the displacement of the excess surface charges is limited by the external boundary of the EDL, and (v) polarization of the `open' double layer, implying free exchange of excess ions with the bulk electrolyte and generation of transient diffusional potentials, which lag behind the applied field. Some theoretical models predict large effective values of relative dielectric constants in the range 10^5 -10^6 at low frequencies. Knowledge of the characteristic signatures of these physical mechanisms is important for the correct interpretation of experimental data. Analysis of existing theories of polarization of heterogeneous media shows that electrical spectroscopy can be

  7. Pore scale heterogeneity in the mineral distribution and surface area of porous rocks

    NASA Astrophysics Data System (ADS)

    Lai, Peter; Moulton, Kevin; Krevor, Samuel

    2014-05-01

    There are long-standing challenges in characterizing reactive transport in porous media at scales larger than individual pores. This hampers the prediction of the field-scale impact of geochemical processes on fluid flow [1]. This is a source of uncertainty for carbon dioxide injection, which results in a reactive fluid-rock system, particularly in carbonate rock reservoirs. A potential cause is the inability of the continuum approach to incorporate the impact of heterogeneity in pore-scale reaction rates. This results in part from pore-scale heterogeneities in surface area of reactive minerals [2,3]. The objective of this study was to quantify heterogeneity in reactive surface and observe the extent of its non-normal character. In this study we describe our work in using micron-scale x-ray imaging and other spectroscopic techniques for the purpose of describing the statistical distribution of reactive surface area within a porous medium, and identifying specific mineral phases and their distribution in 3-dimensions. Using in-house image processing techniques and auxilary charactersation with thin section, electron microscope and spectroscopic techniques we quantified the surface area of each mineral phase in the x-ray CT images. This quantification was validated against nitrogen BET surface area and backscattered electron imaging measurements of the CT-imaged samples. Distributions in reactive surface area for each mineral phase were constructed by calculating surface areas in thousands of randomly selected subvolume images of the total sample, each normalized to the pore volume in that image. In all samples, there is little correlation between the reactive surface area fraction and the volumetric fraction of a mineral in a bulk rock. Berea sandstone was far less heterogeneous and has a characteristic pore size at which a surface area distribution may be used to quantify heterogeneity. In carbonates, heterogeneity is more complex and surface area must be

  8. A numerical manifold method model for analyzing fully coupled hydro-mechanical processes in porous rock masses with discrete fractures

    NASA Astrophysics Data System (ADS)

    Hu, Mengsu; Rutqvist, Jonny; Wang, Yuan

    2017-04-01

    In this study, a numerical manifold method (NMM) model was developed for fully coupled analysis of hydro-mechanical (HM) processes in porous rock masses with discrete fractures. Using an NMM two-cover-mesh system of mathematical and physical covers, fractures are conveniently discretized by dividing the mathematical cover along fracture traces to physical cover, resulting in a discontinuous model on a non-conforming mesh. In this model, discrete fracture deformation (e.g. open and slip) and fracture fluid flow within a permeable and deformable porous rock matrix are rigorously considered. For porous rock, direct pore-volume coupling was modeled based on an energy-work scheme. For mechanical analysis of fractures, a fracture constitutive model for mechanically open states was introduced. For fluid flow in fractures, both along-fracture and normal-to-fracture fluid flow are modeled without introducing additional degrees of freedom. When the mechanical aperture of a fracture is changing, its hydraulic aperture and hydraulic conductivity is updated. At the same time, under the effect of coupled deformation and fluid flow, the contact state may dynamically change, and the corresponding contact constraint is updated each time step. Therefore, indirect coupling is realized under stringent considerations of coupled HM effects and fracture constitutive behavior transfer dynamically. To verify the new model, examples involving deformable porous media containing a single and two sets of fractures were designed, showing good accuracy. Last, the model was applied to analyze coupled HM behavior of fractured porous rock domains with complex fracture networks under effects of loading and injection.

  9. Natural thermal convection in fractured porous media

    NASA Astrophysics Data System (ADS)

    Adler, P. M.; Mezon, C.; Mourzenko, V.; Thovert, J. F.; Antoine, R.; Finizola, A.

    2015-12-01

    In the crust, fractures/faults can provide preferential pathways for fluid flow or act as barriers preventing the flow across these structures. In hydrothermal systems (usually found in fractured rock masses), these discontinuities may play a critical role at various scales, controlling fluid flows and heat transfer. The thermal convection is numerically computed in 3D fluid satured fractured porous media. Fractures are inserted as discrete objects, randomly distributed over a damaged volume, which is a fraction of the total volume. The fluid is assumed to satisfy Darcy's law in the fractures and in the porous medium with exchanges between them. All simulations were made for Rayleigh numbers (Ra) < 150 (hence, the fluid is in thermal equilibrium with the medium), cubic boxes and closed-top conditions. Checks were performed on an unfractured porous medium and the convection cells do start for the theoretical value of Ra, namely 4p². 2D convection was verified up to Ra=800. The influence of parameters such as fracture aperture (or fracture transmissivity), fracture density and fracture length is studied. Moreover, these models are compared to porous media with the same macroscopic permeability. Preliminary results show that the non-uniqueness associated with initial conditions which makes possible either 2D or 3D convection in porous media (Schubert & Straus 1979) is no longer true for fractured porous media (at least for 50porous medium is in good agreement with an unfractured porous medium of the same bulk permeability.

  10. Pure water injection into porous rock with superheated steam and salt in a solid state

    NASA Astrophysics Data System (ADS)

    Montegrossi, G.; Tsypkin, G.; Calore, C.

    2012-04-01

    Most of geothermal fields require injection of fluid into the hot rock to maintain pressure and productivity. The presence of solid salt in porous space may cause an unexpected change in the characteristics of the reservoir and produced fluids, and dramatically affect the profitability of the project. We consider an injection problem of pure water into high temperature geothermal reservoir, saturated with superheated vapour and solid salt. Pure water moves away from injection point and dissolves solid salt. When salty water reaches the low-pressure hot domain, water evaporation occurs and, consequently, salt precipitates. We develop a simplified analytical model of the process and derive the similarity solutions for a 1-D semi-infinite reservoir. These solutions are multi-valued and describe the reduction in permeability and porosity due to salt precipitation at the leading boiling front. If the parameters of the system exceed critical values, then similarity solution ceases to exist. We identify this mathematical behaviour with reservoir sealing in the physical system. The TOUGH2-EWASG code has been used to verify this hypothesis and investigate the precipitate formation for an idealized bounded 1-D geothermal system of a length of 500 m with water injection at one extreme and fluid extraction at the other one. Both boundaries are kept at constant pressure and temperature. The result for the semi-infinite numerical model show that the monotonic grow of the solid salt saturation to reach asymptotic similarity solution generally occurs over a very large length starting from the injection point. Reservoir sealing occurs if solid salt at the initial state occupies a considerable part of the porous space. Numerical experiments for the bounded 500 m system demonstrate that a small amount of salt is enough to get reservoir sealing. Generally, salt tend to accumulate near the production well, and salt plug forms at the elements adjacent to the extraction point. This type

  11. Prediction of fault-related damage zones in porous granular rock using strain energy density criteria

    NASA Astrophysics Data System (ADS)

    Okubo, C. H.; Schultz, R. A.

    2004-12-01

    bands. Further, deformation band intensity for both nucleation and propagation tendencies is predicted and observed to increase toward the fault. These model predictions are consistent with independent observations of fault-related deformation band damage zone architecture from other paradigmatic outcrops in southern Utah and Nevada. By implication, specific locations within a damage zone that have the greatest reductions in fluid conductivity due to deformation band growth can be identified. We show that the tendency for fault growth and interaction within porous granular rock can be systematically predicted based on an understanding of in-situ stress state, fault and/or fold geometry, and rock strength and deformability at the time of deformation. This method is not limited to the prediction of deformation bands, but can also be used to predict the distribution of other types of fractures in other rock types, given that the appropriate critical strain energy density values are determined through laboratory testing for each fracture and rock type.

  12. Multiscale framework for predicting the coupling between deformation and fluid diffusion in porous rocks

    SciTech Connect

    Andrade, José E; Rudnicki, John W

    2012-12-14

    In this project, a predictive multiscale framework will be developed to simulate the strong coupling between solid deformations and fluid diffusion in porous rocks. We intend to improve macroscale modeling by incorporating fundamental physical modeling at the microscale in a computationally efficient way. This is an essential step toward further developments in multiphysics modeling, linking hydraulic, thermal, chemical, and geomechanical processes. This research will focus on areas where severe deformations are observed, such as deformation bands, where classical phenomenology breaks down. Multiscale geometric complexities and key geomechanical and hydraulic attributes of deformation bands (e.g., grain sliding and crushing, and pore collapse, causing interstitial fluid expulsion under saturated conditions), can significantly affect the constitutive response of the skeleton and the intrinsic permeability. Discrete mechanics (DEM) and the lattice Boltzmann method (LBM) will be used to probe the microstructure---under the current state---to extract the evolution of macroscopic constitutive parameters and the permeability tensor. These evolving macroscopic constitutive parameters are then directly used in continuum scale predictions using the finite element method (FEM) accounting for the coupled solid deformation and fluid diffusion. A particularly valuable aspect of this research is the thorough quantitative verification and validation program at different scales. The multiscale homogenization framework will be validated using X-ray computed tomography and 3D digital image correlation in situ at the Advanced Photon Source in Argonne National Laboratories. Also, the hierarchical computations at the specimen level will be validated using the aforementioned techniques in samples of sandstone undergoing deformation bands.

  13. Aquifer Recharge Estimation In Unsaturated Porous Rock Using Darcian And Geophysical Methods.

    NASA Astrophysics Data System (ADS)

    Nimmo, J. R.; De Carlo, L.; Masciale, R.; Turturro, A. C.; Perkins, K. S.; Caputo, M. C.

    2016-12-01

    Within the unsaturated zone a constant downward gravity-driven flux of water commonly exists at depths ranging from a few meters to tens of meters depending on climate, medium, and vegetation. In this case a steady-state application of Darcy's law can provide recharge rate estimates.We have applied an integrated approach that combines field geophysical measurements with laboratory hydraulic property measurements on core samples to produce accurate estimates of steady-state aquifer recharge, or, in cases where episodic recharge also occurs, the steady component of recharge. The method requires (1) measurement of the water content existing in the deep unsaturated zone at the location of a core sample retrieved for lab measurements, and (2) measurement of the core sample's unsaturated hydraulic conductivity over a range of water content that includes the value measured in situ. Both types of measurements must be done with high accuracy. Darcy's law applied with the measured unsaturated hydraulic conductivity and gravitational driving force provides recharge estimates.Aquifer recharge was estimated using Darcian and geophysical methods at a deep porous rock (calcarenite) experimental site in Canosa, southern Italy. Electrical Resistivity Tomography (ERT) and Vertical Electrical Sounding (VES) profiles were collected from the land surface to water table to provide data for Darcian recharge estimation. Volumetric water content was estimated from resistivity profiles using a laboratory-derived calibration function based on Archie's law for rock samples from the experimental site, where electrical conductivity of the rock was related to the porosity and water saturation. Multiple-depth core samples were evaluated using the Quasi-Steady Centrifuge (QSC) method to obtain hydraulic conductivity (K), matric potential (ψ), and water content (θ) estimates within this profile. Laboratory-determined unsaturated hydraulic conductivity ranged from 3.90 x 10-9 to 1.02 x 10-5 m

  14. Pore Scale Heterogeneity in the Mineral Distribution, Surface Area and Adsorption in Porous Rocks

    NASA Astrophysics Data System (ADS)

    Lai, P. E. P.; Krevor, S. C.

    2014-12-01

    The impact of heterogeneity in chemical transport and reaction is not understood in continuum (Darcy/Fickian) models of reactive transport. This is manifested in well-known problems such as scale dependent dispersion and discrepancies in reaction rate observations made at laboratory and field scales [1]. Additionally, this is a source of uncertainty for carbon dioxide injection, which produces a reactive fluid-rock system particularly in carbonate rock reservoirs. A potential cause is the inability of the continuum approach to incorporate the impact of heterogeneity in pore-scale reaction rates. This results in part from pore-scale heterogeneities in surface area of reactive minerals [2, 3]. We use x-ray micro tomography to describe the non-normal 3-dimensional distribution of reactive surface area within a porous medium according to distinct mineral groups. Using in-house image processing techniques, thin sections, nitrogen BET surface area, backscattered electron imaging and energy dispersive spectroscopy, we compare the surface area of each mineral phase to those obtained from x-ray CT imagery. In all samples, there is little correlation between the reactive surface area fraction and the volumetric fraction of a mineral in a bulk rock. Berea sandstone was far less heterogeneous and has a characteristic pore size at which a surface area distribution may be used to quantify heterogeneity. In carbonates, heterogeneity is more complex and surface area must be characterized at multiple length scales for an accurate description of reactive transport. We combine the mineral specific surface area characterisation to dynamic tomography, imaging the flow of water and solutes, to observe flow dependent and mineral specific adsorption. The observations may contribute to the incorporation of experimentally based statistical descriptions of pore scale heterogeneity in reactive transport into upscaled models, moving it closer to predictive capabilities for field scale

  15. Quantify fluid saturation in fractures by light transmission technique and its application

    NASA Astrophysics Data System (ADS)

    Ye, S.; Zhang, Y.; Wu, J.

    2016-12-01

    The Dense Non-Aqueous Phase Liquids (DNAPLs) migration in transparent and rough fractures with variable aperture was studied experimentally using a light transmission technique. The migration of trichloroethylene (TCE) in variable-aperture fractures (20 cm wide x 32.5 cm high) showed that a TCE blob moved downward with snap-off events in four packs with apertures from 100 μm to 1000 μm, and that the pattern presented a single and tortuous cluster with many fingers in a pack with two apertures of 100 μm and 500 μm. The variable apertures in the fractures were measured by light transmission. A light intensity-saturation (LIS) model based on light transmission was used to quantify DNAPL saturation in the fracture system. Known volumes of TCE, were added to the chamber and these amounts were compared to the results obtained by LIS model. Strong correlation existed between results obtained based on LIS model and the known volumes of T CE. Sensitivity analysis showed that the aperture was more sensitive than parameter C2 of LIS model. LIS model was also used to measure dyed TCE saturation in air sparging experiment. The results showed that the distribution and amount of TCE significantly influenced the efficient of air sparging. The method developed here give a way to quantify fluid saturation in two-phase system in fractured medium, and provide a non-destructive, non-intrusive tool to investigate changes in DNAPL architecture and flow characteristics in laboratory experiments. Keywords: light transmission, fluid saturation, fracture, variable aperture AcknowledgementsFunding for this research from NSFC Project No. 41472212.

  16. Mercury porosimetry for comparing piece-wise hydraulic properties with full range pore characteristics of soil aggregates and porous rocks

    NASA Astrophysics Data System (ADS)

    Turturro, Antonietta Celeste; Caputo, Maria C.; Gerke, Horst H.

    2017-04-01

    Unsaturated hydraulic properties are essential in the modeling of water and solute movement in the vadose zone. Since standard hydraulic techniques are limited to specific moisture ranges, maybe affected by air entrapment, wettability problems, limitations due to water vapor pressure, and are depending on the initial saturation, the continuous maximal drying curves of the complete hydraulic functions can mostly not reflect the basic pore size distribution. The aim of this work was to compare the water retention curves of soil aggregates and porous rocks with their porosity characteristics. Soil aggregates of Haplic Luvisols from Loess L (Hneveceves, Czech Republic) and glacial Till T (Holzendorf, Germany) and two lithotypes of porous rock C (Canosa) and M (Massafra), Italy, were analyzed using, suction table, evaporation, psychrometry methods, and the adopted Quasi-Steady Centrifuge method for determination of unsaturated hydraulic conductivity. These various water-based techniques were applied to determine the piece-wise retention and the unsaturated hydraulic conductivity functions in the range of pore water saturations. The pore-size distribution was determined with the mercury intrusion porosimetry (MIP). MIP results allowed assessing the volumetric mercury content at applied pressures up to 420000 kPa. Greater intrusion and porosity values were found for the porous rocks than for the soil aggregates. Except for the aggregate samples from glacial till, maximum liquid contents were always smaller than porosity. Multimodal porosities and retention curves were observed for both porous rocks and aggregate soils. Two pore-size peaks with pore diameters of 0.135 and 27.5 µm, 1.847 and 19.7 µm, and 0.75 and 232 µm were found for C, M and T, respectively, while three peaks of 0.005, 0.392 and 222 µm were identified for L. The MIP data allowed describing the retention curve in the entire mercury saturation range as compared to water retention curves that required

  17. Failure mode, strain localization and permeability evolution in porous sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Vajdova, Veronika

    investigated on dry samples of Indiana and Tavel limestones. Despite the difference in deformation mechanisms, failure modes in the limestones were similar to that of porous sandstones reported in literature: dilatant brittle faulting and compactioe ductile flow at low and high confining pressures, respectively. The observations were interpreted by two micromechanical models. Our data combined with published data characterize pore collapse in carbonate rocks with porosities between 3% and 45%.

  18. Dissolution in Fractured and Porous Rocks - the Cave Formation Paradox and Other Instabilities

    NASA Astrophysics Data System (ADS)

    Szymczak, P.; Ladd, A. J. C.

    2012-04-01

    It has long been realized that limestone caves are solutional in origin; the carbonic acid-enriched groundwater forms a weakly acidic solution which dissolves the surrounding limestone as it percolates through the fracture network. Under the simplest assumptions - uniform flow and linear kinetics - the concentration of reactant decays exponentially with distance into the fracture, making it apparently impossible for long conduits to develop. How does the dissolution get so deep then? The answer until recently has been described in terms of changes in chemical kinetics: in natural calcite the reaction rate decreases by orders of magnitude near saturation, which gives a slightly undersaturated solution possibility to penetrate deeper into the fractured rock. Although this is an appealing and widely accepted resolution of the cave formation paradox, it turns out to be incomplete. Both the computer simulations [1] and laboratory experiments [2] show that a fracture does not necessarily open uniformly across its width, but can develop localized regions of dissolution. We show that there is in fact a universal instability in the equations for fracture dissolution [3], even under the most idealized circumstances: i.e. a fracture modeled as two parallel plates, laminar flow, and linear reaction kinetics at the fracture surfaces. This generic instability provides a more effective means to promote dissolution than changes in chemical kinetics and has a profound effect on how long it takes for breakthrough (when the fracture opens along its whole length) to occur. This instability is related to a similar phenomenon in the reactive flow in porous rocks, first described by Chadam et. al [4] (so-called reactive-infiltration instability). The physical nature of both instabilites is different: the former is associated with an initial, uniform porosity state and the other with a steadily propagating dissolution front that separates regions of high and low porosity. We discuss the

  19. The route to shear failure in a non-porous rock revealed by X-ray microtomography

    NASA Astrophysics Data System (ADS)

    Kandula, Neelima; Renard, Francois; Weiss, Jerome; Cordonnier, Benoit; Kobchenko, Maya

    2017-04-01

    The rocks in the crust of the Earth are heterogeneous at the microscale, which has implications on the mode of failure and the existence of precursors to rupture. Using high-resolution X-ray microtomography technique and a triaxial deformation rig called Hades installed at the European Synchrotron Radiation Facility, it is now possible to simulate in-situ rock deformation under crustal conditions at the laboratory scale. We report experiments on deformation of centimetre-scale cylindrical marble samples under compressive loading and confining pressure in the range 20 to 30 MPa. The rock is non-porous and the heterogeneities correspond to the grains and grain boundaries. High-resolution X-ray microtomography acquisitions at a voxel size of 6.5 micrometers are performed while the axial load is increased in steps until reaching the shear failure of the sample. Failure is preceded by numerous micro-fracturing events, which we call damage, that ultimately accumulate into a shear fault. Damage volume and sample density show significant accelerations with applied differential stress before rupture, indicating that precursory signals are present before rupture. This acceleration of damage towards the peak stress as well as the associated micro-fracture size distributions show power-law scaling that argues for an interpretation of rock failure as a critical phenomenon. The present study, therefore, sheds new light on precursory phenomena preceding failure in low-porosity carbonate rocks, which can be of help in unraveling the physics of precursors to earthquakes.

  20. Ln-Co-based rock-salt-type porous coordination polymers: vapor response controlled by changing the lanthanide ion.

    PubMed

    Kobayashi, Atsushi; Suzuki, Yui; Ohba, Tadashi; Noro, Shin-ichiro; Chang, Ho-Chol; Kato, Masako

    2011-03-21

    We synthesized new porous coordination polymers (PCPs) {Ln(III)[Co(III)(dcbpy)(3)]·nH(2)O} (Ln = La(3+), Nd(3+), Gd(3+); H(2)dcbpy = 4,4'-dicarboxy-2,2'-bipyridine) and characterized them by X-ray diffraction and vapor-adsorption measurements. These three Ln-Co-based PCPs have similar rock-salt types and highly symmetrical porous structure and show a reversible structural collapse-regeneration accompanied by water-vapor desorption-adsorption. Similar structural regeneration was also observed for the Gd-Co PCP upon exposure to MeOH and CH(3)CN vapors, whereas the remaining two PCPs barely responded to organic vapors.

  1. Full waveform inversion of seismic waves reflected in a stratified porous medium

    NASA Astrophysics Data System (ADS)

    De Barros, Louis; Dietrich, Michel; Valette, Bernard

    2010-09-01

    In reservoir geophysics applications, seismic imaging techniques are expected to provide as much information as possible on fluid-filled reservoir rocks. Since seismograms are, to some degree, sensitive to the mechanical parameters and fluid properties of porous media, inversion methods can be devised to directly estimate these quantities from the waveforms obtained in seismic reflection experiments. An inversion algorithm that uses a generalized least-squares, quasi-Newton approach is described to determine the porosity, permeability, interstitial fluid properties and mechanical parameters of porous media. The proposed algorithm proceeds by iteratively minimizing a misfit function between observed data and synthetic wavefields computed with the Biot theory. Simple models consisting of plane-layered, fluid-saturated and poro-elastic media are considered to demonstrate the concept and evaluate the performance of such a full waveform inversion scheme. Numerical experiments show that, when applied to synthetic data, the inversion procedure can accurately reconstruct the vertical distribution of a single model parameter, if all other parameters are perfectly known. However, the coupling between some of the model parameters does not permit the reconstruction of several model parameters at the same time. To get around this problem, we consider composite parameters defined from the original model properties and from a priori information, such as the fluid saturation rate or the lithology, to reduce the number of unknowns. Another possibility is to apply this inversion algorithm to time-lapse surveys carried out for fluid substitution problems, such as CO2 injection, since in this case only a few parameters may vary as a function of time. We define a two-step differential inversion approach which allows us to reconstruct the fluid saturation rate in reservoir layers, even though the medium properties are poorly known.

  2. Magnetic Resonance Poroelastography: An Algorithm for Estimating the Mechanical Properties of Fluid-Saturated Soft Tissues

    PubMed Central

    Perriñez, Phillip R.; Kennedy, Francis E.; Van Houten, Elijah E. W.; Weaver, John B.; Paulsen, Keith D.

    2010-01-01

    Magnetic Resonance Poroelastography (MRPE) is introduced as an alternative to single-phase model-based elastographic reconstruction methods. A three-dimensional (3D) finite element poroelastic inversion algorithm was developed to recover the mechanical properties of fluid-saturated tissues. The performance of this algorithm was assessed through a variety of numerical experiments, using synthetic data to probe its stability and sensitivity to the relevant model parameters. Preliminary results suggest the algorithm is robust in the presence of noise and capable of producing accurate assessments of the underlying mechanical properties in simulated phantoms. Further, a 3D time-harmonic motion field was recorded for a poroelastic phantom containing a single cylindrical inclusion and used to assess the feasibility of MRPE image reconstruction from experimental data. The elastograms obtained from the proposed poroelastic algorithm demonstrate significant improvement over linearly elastic MRE images generated using the same data. In addition, MRPE offers the opportunity to estimate the time-harmonic pressure field resulting from tissue excitation, highlighting the potential for its application in the diagnosis and monitoring of disease processes associated with changes in interstitial pressure. PMID:20199912

  3. The effect of fluid saturation on the dynamic shear modulus of tight sandstones

    NASA Astrophysics Data System (ADS)

    Li, Dongqing; Wei, Jianxin; Di, Bangrang; Ding, Pinbo; Shuai, Da

    2017-10-01

    Tight sandstones have become important targets in the exploration of unconventional oil and gas reservoirs. However, due to low porosity, low permeability, complex pore structure and other petrophysical properties of tight sandstones, the applicability of Gassmann’s fluid substitution procedure becomes debatable. Aiming at this problem, this paper attempts to explore the applicability of Gassmann’s theory in tight sandstones. Our focus is to investigate the sensitivity of dynamic shear modulus to fluid saturation and the possible mechanism. Ultrasonic velocity in dry and saturated tight sandstone samples was measured in the laboratory under an effective pressure within the range of 1-60 MPa. This study shows that the shear modulus of the water-saturated samples appears to either increase or decrease, and the soft porosity model (SPM) can be used to quantitatively estimate the variation of shear modulus. Under the condition of in situ pressure, samples dominated by secondary pores and microcracks are prone to show shear strengthening with saturation, which is possibly attributed to the local flow dispersion. Samples that mainly have primary pores are more likely to show shear weakening with saturation, which can be explained by the surface energy mechanism. We also find good correlation between changes in shear modulus and inaccurate Gassmann-predicted saturated velocity. Therefore, understanding the variation of shear modulus is helpful to improving the applicability of Gassmann’s theory in tight sandstones.

  4. On wavemodes at the interface of a fluid and a fluid-saturated poroelastic solid.

    PubMed

    van Dalen, K N; Drijkoningen, G G; Smeulders, D M J

    2010-04-01

    Pseudo interface waves can exist at the interface of a fluid and a fluid-saturated poroelastic solid. These waves are typically related to the pseudo-Rayleigh pole and the pseudo-Stoneley pole in the complex slowness plane. It is found that each of these two poles can contribute (as a residue) to a full transient wave motion when the corresponding Fourier integral is computed on the principal Riemann sheet. This contradicts the generally accepted explanation that a pseudo interface wave originates from a pole on a nonprincipal Riemann sheet. It is also shown that part of the physical properties of a pseudo interface wave can be captured by loop integrals along the branch cuts in the complex slowness plane. Moreover, it is observed that the pseudo-Stoneley pole is not always present on the principal Riemann sheet depending also on frequency rather than on the contrast in material parameters only. Finally, it is shown that two additional zeroes of the poroelastic Stoneley dispersion equation, which are comparable with the P-poles known in nonporous elastic solids, do have physical significance due to their residue contributions to a full point-force response.

  5. Approach to failure in a discrete element model of the compressive failure of porous rocks (Invited)

    NASA Astrophysics Data System (ADS)

    Kun, F.; Varga, I.; Lennartz-Sassinek, S.; Main, I. G.

    2013-12-01

    We investigate how a porous rock sample approaches failure under uniaxial compression. Computer simulations are carried out in the framework of a discrete element model (DEM) which takes into account both the microstructure of the material and the dynamics of local fracturing, revealing much more detail and observation bandwidth in then granular mechanics than possible during standard laboratory tests. The synthetic sample is generated by sedimentation of randomly-sized spherical particles with a log-normal size distribution inside a cylindrical container. The cohesive interaction of particles is represented by beam elements that break when overstressed. The breaking rule takes into account both stretching and shear of particle contacts. When particles not connected by a beam come into contact their interaction is described by the Hertz contact law. The time evolution of the system is generated by molecular dynamics simulations in three dimensions. Computer simulations showed that under strain controlled uniaxial loading of the system micro-cracks initially nucleate in an uncorrelated way all over the sample. As loading proceeds localization occurs, i.e. the damage concentrates into a narrow damage band. Inside the damage band the material is crushed, into a poorly sorted mixture of fine powder and larger fragments with a power-law mass distribution, as observed in fault wear products (gouge) in natural and laboratory faults. Dynamic bursts of radiated energy, analogous to acoustic emissions observed in laboratory experiments, are identified as correlated trails of local fracture emerging as the consequence of stress redistribution. Characteristic quantities of burst such as size/rupture area, released elastic energy, and duration proved to have power law probability-size distributions over a broad range. The energy and duration of bursts have power law dependence on the rupture area created. As the system approaches macroscopic failure consecutive bursts become

  6. Hydromechanical Imaging of Fractured-Porous Rocks Properties and Coupled Processes

    NASA Astrophysics Data System (ADS)

    Guglielmi, Y.; Cappa, F.; Rutqvist, J.; Wang, J. S.

    2009-12-01

    The High-Pulse Poroelasticity Protocol (HPPP) project is dedicated to geophysical monitoring of CO2 injection in reservoirs (http://hppp.unice.fr/), focusing currently on hydromechanical testing in carbonate rock. The HPPP probe uses fiber-optic sensors for dynamic fluid pressure/mechanical deformation measurements in boreholes, with reflection of light at specific wavelength from fiber Bragg gratings mounted between inflatable packers. The probe requires no downhole electrical supply, thus the operation is passive, with response time << 0.5 ms and probe sizes from ~12 to ~25 mm. The sensor is immune to EM interference, and can stand harsh environments. The probe laboratory and in situ calibration and the development of receiving array of sensors around HPPP are established prior to borehole installation. The field measurements include the detection of coupled seismic - poroelastic waves (Fast Biot Waves) in saturated and unsaturated zones. Within the injection chamber, seismic pressure waves of 1 to 10 Hz and static hydraulic diffusion are measured to quantify the coupling to the reservoir. Oscillations with period of several ms are induced by the onset of fluid pulses and quickly reach quasi-static state with high pressure maintained for seconds. The accuracies of fiber optical displacement sensor is 10-7 m and pressure sensor 103 Pa. In the rock medium, 3D MEM accelerometers with frequency range of 0 - 1 kHz can be mounted with distances of deci-meters to meters from the HPPP probe. Undrained responses with strong differences in amplitude and shape between velocity components are detected right after the rise of fluid pressure. After the pressure pulse, seismicity related to pulse pressure diffusion is detected. Accelerometers are also deployed in the Coaraze site (in southeastern France) with both fault related fractures and bedding planes well characterized. Water tables can be raised or lowered in the fracture/porous block by closing and opening a spring

  7. Seismic tomography in the lab-interferometry in a porous, scattering medium under pressure

    NASA Astrophysics Data System (ADS)

    Boschi, Lapo; Latour, Soumaya; Colombi, Andrea; Schubnel, Alexandre

    2015-04-01

    Our laboratory experiments and numerical simulations aim at determining the accuracy and reliability of seismic interferometry as an imaging and monitoring tool. In our analogue experiments, seismic waves are transmitted, via transducers, into rock samples under pressure, or are generated as the samples crack along a fault. We record the resulting signal at a number of receivers over the sample, and analyze those data via seismic inteferometry. Our samples include porous, scattering rocks, both dry and fluid-saturated, isotropic and anisotropic. The experimental apparatus we utilize allows to reproduce pressure and temperature conditions found in the Earth's crust. We so evaluate the role of isotropic and/or anisotropic cracking and fluid saturation (depending, in turn, on the fluid's viscosity) on wave propagation and, specifically, on the system's impulse response (Green's function). Whether the Green's function is correctly reconstructed by interferometry is in itself a signficant theoretical question that we also address. Numerical (spectral-element via SPECFEM) modeling allows to disentangle the role of various parameters who affect Green's function reconstructuon, e.g. source distribution which is particularly hard to control in analogue experiments.

  8. Linking the pressure dependency of elastic and electrical properties of porous rocks by a dual porosity model

    NASA Astrophysics Data System (ADS)

    Han, Tongcheng; Gurevich, Boris; Pervukhina, Marina; Clennell, Michael Ben; Zhang, Junfang

    2016-04-01

    Knowledge about the pressure dependency of elastic and electrical properties is important for a variety of geophysical applications. We present a technique to invert for the stiff and compliant porosity from velocity measurements made as a function of differential pressure on saturated sandstones. A dual porosity concept is used for dry rock compressibility and a squirt model is employed for the pressure and frequency dependent elastic properties of the rocks when saturated. The total porosity obtained from inversion shows satisfactory agreement with experimental results. The electrical cementation factor was determined using the inverted porosity in combination with measured electrical conductivity. It was found that cementation factor increased exponentially with increasing differential pressure during isostatic loading. Elastic compressibility, electrical cementation factor and electrical conductivity of the saturated rocks correlate linearly with compliant porosity, and electrical cementation factor and electrical conductivity exhibit linear correlations with elastic compressibility of the saturated rocks under loading. The results show that the dual porosity concept is sufficient to explain the pressure dependency of elastic, electrical and joint elastic-electrical properties of saturated porous sandstones.

  9. Combined positron emission tomography and computed tomography to visualize and quantify fluid flow in sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Fernø, M. A.; Gauteplass, J.; Hauge, L. P.; Abell, G. E.; Adamsen, T. C. H.; Graue, A.

    2015-09-01

    Here we show for the first time the combined positron emission tomography (PET) and computed tomography (CT) imaging of flow processes within porous rocks to quantify the development in local fluid saturations. The coupling between local rock structure and displacement fronts is demonstrated in exploratory experiments using this novel approach. We also compare quantification of 3-D temporal and spatial water saturations in two similar CO2 storage tests in sandstone imaged separately with PET and CT. The applicability of each visualization technique is evaluated for a range of displacement processes, and the favorable implementation of combining PET/CT for laboratory core analysis is discussed. We learn that the signal-to-noise ratio (SNR) is over an order of magnitude higher for PET compared with CT for the studied processes.

  10. Porous reservoir rocks with fluids: Reservoir transport properties and reservoir conditions

    SciTech Connect

    Nur, Amos

    2004-01-22

    During the past three years we have carried out research efforts in three areas: (1) Modeling rock physical properties; (2) Properties and behavior of sediments with gas hydrates; and (3) Detectionand production of subsurface overpressure. Results were published in the informal Stanford Rock Physics reports, refereed papers and PhD theses, as detailed below.

  11. Variations in hydraulic conductivity with scale of measurement during aquifer tests in heterogeneous, porous carbonate rocks

    NASA Astrophysics Data System (ADS)

    Schulze-Makuch, Dirk; Cherkauer, Douglas S.

    Previous studies have shown that hydraulic conductivity of an aquifer seems to increase as the portion of the aquifer tested increases. To date, such studies have all relied on different methods to determine hydraulic conductivity at each scale of interest, which raises the possibility that the observed increase in hydraulic conductivity is due to the measurement method, not to the scale. This study analyzes hydraulic conductivity with respect to scale during individual aquifer tests in porous, heterogeneous carbonate rocks in southeastern Wisconsin, USA. Results from this study indicate that hydraulic conductivity generally increases during an individual test as the volume of aquifer impacted increases, and the rate of this increase is the same as the rate of increase determined by using different measurement methods. Thus, scale dependence of hydraulic conductivity during single tests does not depend on the method of measurement. This conclusion is supported by 22 of 26 aquifer tests conducted in porous-flow-dominated carbonate units within the aquifer. Instead, scale dependency is probably caused by heterogeneities within the aquifer, a conclusion supported by digital simulation. All of the observed types of hydraulic-conductivity variations with scale during individual aquifer tests can be explained by a conceptual model of a simple heterogeneous aquifer composed of high-conductivity zones within a low-conductivity matrix. Résumé Certaines études ont montré que la conductivité hydraulique d'un aquifère semble augmenter en même temps que la partie testée de l'aquifère s'étend. Jusqu'à présent, ces études ont toutes reposé sur des méthodes de détermination de la conductivité hydraulique différentes pour chaque niveau d'échelle, ce qui a conduit à penser que l'augmentation observée de la conductivité hydraulique pouvait être due aux méthodes de mesure et non à l'effet d'échelle. Cette étude analyse la conductivité hydraulique par

  12. A coupled thermo-poro-mechanical finite element analysis of fractured porous rocks using a cohesive interface element

    NASA Astrophysics Data System (ADS)

    Wang, W.; Regueiro, R. A.

    2014-12-01

    The coupling between multiphase flow, heat transfer, and poromechanics in fractured geomaterials has aroused great interest in the areas of geomechanics, geoenvironmental engineering, and petroleum engineering. Relevant applications include nuclear waste repositories, geological sequestration of CO2, geothermal systems, and exploitation of shale gas reservoirs. The paper presents a fully coupled thermo-poro-mechanical (TPM) cohesive interface element (CIE) model, which can represent fluid and heat flow along and across the fracture, and shear/normal deformation of the fracture surfaces. The proposed model is then applied to analyze two popular geological engineering problems using the finite element method (FEM) with a small strain formulation. The first application is the fracturing process in organic-rich shale due to heating. In the finite element analysis, multiple horizontal microcracks parallel to the bedding plane are assumed to preexist in the porous source rock, and are represented by coupled TPM cohesive interface elements. The porous bulk rock is assumed to be homogeneous, isotropic (for the time being, with transverse isotropy a natural extension), and linearly elastic. The excess pore fluid pressure, which mainly causes the development of the fractures, is actually induced by the rapid decomposition of organic matter during heating according to the literature. However, the involved complex chemical reaction process is beyond the scope of the paper, and is therefore substituted by a fluid injection process within the cracks under room temperature (25C) and high temperature (400C) in the paper. We investigate the fracture propagation due to pore fluid pressure increase and the development of fracture-induced permeability. The second application is a nuclear waste repository in a partially saturated fractured rock. Multiphase transport of moisture and heat, thermally-induced stress, as well as the change of fracture apertures are investigated due to short

  13. Rocks.

    ERIC Educational Resources Information Center

    Lee, Alice

    This science unit is designed for limited- and non-English speaking students in a Chinese bilingual education program. The unit covers rock material, classification, characteristics of types of rocks, and rock cycles. It is written in Chinese and simple English. At the end of the unit there is a list of main terms in both English and Chinese, and…

  14. The effect of X-ray micro computed tomography image resolution on flow properties of porous rocks.

    PubMed

    Latief, F D E; Fauzi, U; Irayani, Z; Dougherty, G

    2017-04-01

    The study of digital rock physics has seen significant advances due to the development of X-ray micro computed tomography scanning devices. One of the advantages of using such a device is that the pore structure of rock can be mapped down to the micrometre level in three dimensions. However, in providing such high-resolution images (low voxel size), the resulting file sizes are necessarily large (of the order of gigabytes). Lower image resolution (high voxel size) produces smaller file sizes (of the order of hundreds of megabytes), but risks losing significant details. This study describes the effect of the image resolution obtained by means of hardware-based and software-based approach. Four samples of porous rock were scanned using a SkyScan 1173 High Energy Micro-CT. We found that acquisition using increased pixel binning of the camera (hardware-based resizing) significantly affects the calculated physical properties of the samples. By contrast, voxel resizing by means of a software-based approach during the reconstruction process yielded less effect on the porosity and specific surface area of the samples. However, the decreasing resolution of the image obtained by both the hardware-based and the software-based approaches affects the permeability significantly. We conclude that simulating fluid flow through the pore space using the Lattice Boltzmann method to calculate the permeability has a significant dependency on the image resolution.

  15. Stress impact on elastic anisotropy of triclinic porous and fractured rocks

    NASA Astrophysics Data System (ADS)

    Shapiro, S. A.

    2017-03-01

    Understanding the stress dependence of elastic properties of rocks is important for reservoir characterization and seismic-hazard monitoring. Several known approaches describing this dependence are the following: the nonlinear elasticity theory, effective-medium theories for fractured rocks with stress-dependent crack densities, and the piezosensitivity approach (also called the porosity deformation approach). Here I propose a generalization of the piezosensitivity approach to triclinic rocks. I assume the isotropy of the tensor describing sensitivity of elasticity to small strains of the pore space, and generalize known linear and exponential stress dependencies of compliances. This generalization is capable of describing the effect of loads on elastic properties of anisotropic rocks when the principal stresses are not necessarily aligned with the symmetrical axes of the unstressed anisotropic material. For example, the generalization describes how monoclinic anisotropy changes under isostatic stress or pore pressure, and how tilted transverse isotropy changes to monoclinic anisotropy due to a pseudo-triaxial (or a uniaxial) load. The results are expected to be valid up to several hundred megapascals. This theory is closely related to the two other approaches mentioned above. On the one hand, for unloaded rocks, the theory is consistent with the noninteracting scalar-crack approximation. On the other hand, the theory's predictions of mutual relations between isotropic third-order elastic moduli is in good agreement with literature data on corresponding laboratory measurements. Thus, using the piezosensitivity approach, the physical nonlinearity of rocks can quantitatively be rather well explained by the strain of compliant pores.

  16. A Circuit Model for the Measurement of the Streaming Potential in a Rock Sample

    NASA Astrophysics Data System (ADS)

    Yin, C.; Wang, J.; Qiu, A.; Liu, X.; Hu, H.

    2012-04-01

    Streaming potential is usually defined under the assumption that the rock sample under consideration is not connected electrically to any external circuit. In this study we investigate experimentally the effect of the external circuit on the measurement of the streaming potential. Cations usually dominate anions in the diffuse layer in the pore canals in a fluid-saturated porous sandstone sample. When a pressure difference is applied to the sample, fluid flows in the pores and causing a convective current due to the cation-dominate motion. With the separation of opposite ions at the two ends, a streaming potential occurs, and results in a conductive current. Those two current will be opposite and equal in value so that the streaming potential does not change. But in any experimental measurement of the streaming potential, the rock sample is not isolated in the circuit. An external circuit is necessary for the measurement of the potential difference at the ends of the sample. This external circuit will divert the flow of charges. This study investigates the effect of the external circuit on the convective current and conductive current in the pores by experiments, and gives an equivalent circuit model for the two currents. We connect an external resistance Rext to the ends of the fluid-saturated rock sample, and measure the potential difference at the ends of the sample . The impedance of the fluid-saturated rock sample Zrock is definite under a given salinity and can be separately measured. The circuit is governed by the following equations, Urock = ZrockIcond, (1) Urock = RextIext, (2) Iconv + Icond +Iext = 0, (3) where Iconv is the convective current, Icond is the conductive current, Iext is the external current and Urock is the potential difference at the ends of the rock sample. From the above three equations, we get - Urock(Zrock + Rext) Iconv = ---Z--R----- . rock ext (4) We repeated the measurement under different external resistance Rext. The computed

  17. From hydrofracture to gaseofracture in porous rocks: influence of the nature of the injection fluid on the process

    NASA Astrophysics Data System (ADS)

    Johnsen, O.; Chevalier, C.; Toussaint, R.; Lindner, A.; Niebling, M.; Schmittbuhl, J.; Maloy, K. J.; Clement, E.; Flekkoy, E. G.

    2009-04-01

    We present experimental systems where we inject a fluid at high pressure in a poorly cohesive porous material saturated with the same fluid. This fluid is either a highly compressible gas (air), or an almost incompressible and viscous fluid (oil), in an otherwise identical porous matrix. We compare both situations. These porous materials are designed as analogs to real rocks in terms of processes, but their cohesion and geometry are tuned so that the hydrofracture process can be followed optically in the lab, in addition to the ability to follow the imposed pressure and fluxes. Namely, we work with lowly cohesive granular materials, confined in thin elongated Hele-Shaw cell, and follow it with high speed cameras. The fluid is injected on the side of the material, and the injection overpressure is maintained constant after the start. At sufficiently high overpressures, the mobilization of grains is observed, and the formation of hydrofracture fingering patterns is followed and analyzed quantitatively. The two situations where air is injected and where oil is injected are compared together. Many striking similarities are observed between both situations about the shape selections and dynamics, when time is rescaled according to the viscosity of the interstitial fluid. Some differences survive in the speed of the traveling hydrofracture, and their physical origin is discussed. In practice, this problem is relevant for important aspects in the formation and sustenance of increased permeability macroporous networks as demonstrated in nature and industry in many situations. E.g., in active hydrofracture in boreholes, piping/internal erosion in soils and dams, sand production in oil or water wells, and wormholes in oil sands. It is also important to understand the formation of macroporous channels, and the behavior of confined gouges when overpressured fluids are mobilized in seismic sources. Indeed, the formation of preferential paths in this situation can severely

  18. Prediction of crack density in porous-cracked rocks from elastic wave velocities

    NASA Astrophysics Data System (ADS)

    Byun, Ji-Hwan; Lee, Jong-Sub; Park, Keunbo; Yoon, Hyung-Koo

    2015-04-01

    The stability of structures that are built over rock is affected by cracks in the rock that result from weathering, thawing and freezing processes. This study investigates a new method for determining rock crack densities using elastic wave velocities. The Biot-Gassmann model, which consists of several elastic moduli and Poisson's ratio, was used to determine a theoretical equation to predict the crack density of rocks. Ten representative specimens were extracted from ten boreholes to highlight the spatial variability. Each specimen was characterized using X-Ray Diffraction (XRD) analysis. The specimens were carved into cylinders measuring 50 mm in diameter and 30 mm in height using an abrasion process. A laboratory test was performed to obtain the elastic wave velocity using transducers that can transmit and receive compressional and shear waves. The measured compressional wave and shear wave velocities were approximately 2955 m/s-5209 m/s and 1652 m/s-2845 m/s, respectively. From the measured elastic wave velocities, the analyzed crack density and crack porosity were approximately 0.051-0.185 and 0.03%-0.14%, respectively. The calculated values were compared with the results of previous studies, and they exhibit similar values and trends. The sensitivity of the suggested theoretical equation was analyzed using the error norm technique. The results show that the compressional wave velocity and the shear modulus of a particle are the most influential factors in this equation. The study demonstrates that rock crack density can be estimated using the elastic wave velocities, which may be useful for investigating the stability of structures that are built over rock.

  19. Effect of fracture fill on seismic attenuation and dispersion in fractured porous rocks

    NASA Astrophysics Data System (ADS)

    Kong, Liyun; Gurevich, Boris; Müller, Tobias M.; Wang, Yibo; Yang, Huizhu

    2013-12-01

    When a porous medium is permeated by open fractures, wave-induced flow between pores and fractures can cause significant attenuation and dispersion. Most studies of this phenomenon assume that pores and fractures are saturated with the same fluid. In some situations, particularly when a fluid such as water or carbon dioxide is injected into a tight hydrocarbon reservoir, fractures may be filled with a different fluid (with capillary forces preventing fluid mixing). Here we develop a model for wave propagation in a porous medium with aligned fractures where pores and fractures are filled with different fluids. The fractured medium is modelled as a periodic system of alternating layers of two types: thick porous layers representing the background, and very thin and highly compliant porous layers representing fractures. A dispersion equation for the P-wave propagating through a layered porous medium is derived using Biot's theory of wave propagation in periodically stratified poroelastic media. By taking the limit of zero thickness and zero normal stiffness of the thin layers, we obtain expressions for dispersion and attenuation of the P waves. The results show that in the low-frequency limit the elastic properties of such a medium can be described by Gassmann's equation with a composite fluid, whose bulk modulus is a harmonic (Wood) average of the moduli of the two fluids. The dispersion is relatively large when the fluid in both pores and fractures is liquid, and also when the pores are filled with a liquid but fractures are filled with a highly compressible gas. An intermediate case exists where the fluid in the pores is liquid while the fluid in the fractures has a bulk modulus between those of liquid and gas. In this intermediate case no dispersion is observed. This can be explained by observing that for uniform saturation, wave-induced compression causes flow from fractures into pores due to the high compliance of the fractures. Conversely, when pores are filled

  20. Semiarid watershed response to low-tech porous rock check dams

    USDA-ARS?s Scientific Manuscript database

    Rock check dams are used throughout the world as a technique for mitigating erosion problems on degraded lands. Increasingly, they are being used in restoration efforts on rangelands in the southwestern US; however, their impact on watershed response and channel morphology is not well quantified. In...

  1. Microcracking during triaxial deformation of porous rocks monitored by changes in rock physical properties, I. Elastic-wave propagation measurements on dry rocks

    NASA Astrophysics Data System (ADS)

    Ayling, Mark R.; Meredith, Philip G.; Murrell, Stanley A. F.

    1995-05-01

    We present results from two series of triaxial deformation experiments performed on "dry" samples of two sandstones (Darley Dale and Gosford) carried out at confining pressures from 25 MPa to 200 MPa. Over this pressure range the mode of failure in both these sandstones passes from localized brittle failure with a clear through-going fault to distributed cataclastic flow. During these experiments, stress, strain, compressional-wave velocity ( VP) and shear-wave velocity ( VS) measurements were made simultaneously in the direction of the maximum principal compressive loading axis. Initial application of the hydrostatic confining pressure causes both VP and VS to increase, and upon raising the axial stress above the confining pressure both velocities increase further at first (generally by only a few percent), but then decrease as dilatant crack growth commences. During dilatancy, VS decreases proportionately more than VP, and this decrease is generally of the order of 10-15%. These velocity measurements allow changes in rock physical properties to be calculated along with the axial and transverse crack volume density parameters, ɛX and ɛZ. The results from two selected tests are analysed in detail. These tests were chosen because they exhibit; (a) typical brittle shear failure, and (b) typical ductile cataclastic flow, respectively. The full interrogating elastic waveforms were also recorded during testing, and these have been used to calculate the seismic quality factors QP and QS. To our knowledge, this is the first time this has been reported for rock samples undergoing triaxial deformation. The changes in Q values generally exhibit similar trends to those observed in the velocity measurements, but the percentage changes in Q are an order of magnitude greater, suggesting that this parameter is a more sensitive measure of dilatant crack damage. The measurements on dry rock samples reported here provide the basis for comparison with measurments of changes in

  2. Reactive transport and mineral dissolution in fractured and porous rock: experiments, models and field observations

    NASA Astrophysics Data System (ADS)

    Dutka, Filip; Osselin, Florian; Kondratiuk, Paweł; Szymczak, Piotr

    2017-04-01

    We analyze the evolution of the shape of a dissolving porous body immersed in a reactive fluid. First, we consider the case of a semi-infinite body and transport-limited dissolution and show that in this case the resulting shape is parabolic. We derive the dissolution rate of such shapes depending on the contrast of permeabilities between the body and the surrounding matrix both in two and three spatial dimensions. Next, we consider a problem of the dissolution of a finite-sized porous object in a Hele-Shaw cell. We study this system both experimentally and numerically. In the experiment, we use a microfluidic chip with a gypsum block inserted in between two parallel polycarbonate plates. By changing the flow rate and the distance between the plates we can scan a relatively wide range of Péclet and Damköhler numbers, which characterize the relative magnitude of advection, diffusion and reaction in the system. The evolving geometries are captured by a camera and then analyzed by image-processing techniques. The experiments show a number of unexpected regularities. In particular, the upstream (trailing) edge of the dissolving object is shown to advance with a constant velocity whereas its curvature is changing in time. If the object had initially a sharp tip pointing upstream, its radius of curvature first increases and then decreases in time. Finally, we compare the obtained dissolution shapes with the natural forms such as pinnacles in a surface karst.

  3. Micro-poromechanics model of fluid-saturated chemically active fibrous media

    PubMed Central

    Misra, Anil; Parthasarathy, Ranganathan; Singh, Viraj; Spencer, Paulette

    2014-01-01

    We have developed a micromechanics based model for chemically active saturated fibrous media that incorporates fiber network microstructure, chemical potential driven fluid flow, and micro-poromechanics. The stress-strain relationship of the dry fibrous media is first obtained by considering the fiber behavior. The constitutive relationships applicable to saturated media are then derived in the poromechanics framework using Hill’s volume averaging. The advantage of this approach is that the resultant continuum model accounts for the discrete nature of the individual fibers while retaining a form suitable for porous materials. As a result, the model is able to predict the influence of micro-scale phenomena, such as the fiber pre-strain caused by osmotic effects and evolution of fiber network structure with loading, on the overall behavior and in particular, on the poromechanics parameters. Additionally, the model can describe fluid-flow related rate-dependent behavior under confined and unconfined conditions and varying chemical environments. The significance of the approach is demonstrated by simulating unconfined drained monotonic uniaxial compression under different surrounding fluid bath molarity, and fluid-flow related creep and relaxation at different loading-levels and different surrounding fluid bath molarity. The model predictions conform to the experimental observations for saturated soft fibrous materials. The method can potentially be extended to other porous materials such as bone, clays, foams and concrete. PMID:25755301

  4. Micro-poromechanics model of fluid-saturated chemically active fibrous media.

    PubMed

    Misra, Anil; Parthasarathy, Ranganathan; Singh, Viraj; Spencer, Paulette

    2015-02-01

    We have developed a micromechanics based model for chemically active saturated fibrous media that incorporates fiber network microstructure, chemical potential driven fluid flow, and micro-poromechanics. The stress-strain relationship of the dry fibrous media is first obtained by considering the fiber behavior. The constitutive relationships applicable to saturated media are then derived in the poromechanics framework using Hill's volume averaging. The advantage of this approach is that the resultant continuum model accounts for the discrete nature of the individual fibers while retaining a form suitable for porous materials. As a result, the model is able to predict the influence of micro-scale phenomena, such as the fiber pre-strain caused by osmotic effects and evolution of fiber network structure with loading, on the overall behavior and in particular, on the poromechanics parameters. Additionally, the model can describe fluid-flow related rate-dependent behavior under confined and unconfined conditions and varying chemical environments. The significance of the approach is demonstrated by simulating unconfined drained monotonic uniaxial compression under different surrounding fluid bath molarity, and fluid-flow related creep and relaxation at different loading-levels and different surrounding fluid bath molarity. The model predictions conform to the experimental observations for saturated soft fibrous materials. The method can potentially be extended to other porous materials such as bone, clays, foams and concrete.

  5. Fluid-Rock Characterization and Interactions in NMR Well Logging

    SciTech Connect

    Hirasaki, George J.; Mohanty, Kishore, K.

    2001-07-13

    The objective of this project is to characterize the fluid properties and fluid-rock interactions that are needed for formation evaluation by NMR well logging. This is the first annual progress report submitted to the DOE. It reports on the work completed during the reporting period even if it may have started before this period. This project is a partnership between Professor George J. Hirasaki at Rice University and Professor Kishore Mohanty at University of Houston. In addition to the DOE, this project is supported by a consortium of oil companies and service companies. The fluid properties characterization has emphasized the departure of live oils from correlations based on dead oils. Also, asphaltic components can result in a difference between the T1 and T2 relaxation time distributions as well as reduce the hydrogen index. The fluid rock characterizations that are reported here are the effects of wettability and internal magnetic field gradients. A pore reconstruction method ha s been developed to recreate three-dimensional porous media from two-dimensional images that reproduce some of their key statistical properties. A Monte Carlo simulation technique has been developed to calculate the magnetization decay in fluid saturated porous media given their pore structure.

  6. Footprints of spontaneous fluid redistribution on capillary pressure in porous rock

    NASA Astrophysics Data System (ADS)

    Helland, Johan Olav; Friis, Helmer André; Jettestuen, Espen; Skjæveland, Svein M.

    2017-05-01

    Pore-scale imaging of two-phase flow in porous media shows that pore filling occurs as cooperative events with accompanying spontaneous fluid redistribution in other parts of the pore space. We present a level set method that controls saturation quasi-statically to model experiments controlled by low, constant flow rates and demonstrate that our method can describe the observed displacement mechanisms. The level set approach determines states of capillary equilibrium, which generally are different for displacement protocols constrained by saturation and pressure. Saturation-controlled simulations of drainage in sandstone show spontaneous fluid redistributions with abrupt pressure jumps and cooperative behavior, including snap-off and interface retraction events, consistent with experimental observations. Drainage capillary pressure curves are lower when saturation, rather than pressure, controls displacement. Remarkably, these effects are less significant for imbibition processes where the development of hydraulically connected wetting phase moderates the cooperative behavior and associated pressure jumps.

  7. Growth of compaction bands: A new deformation mode for porous rock

    SciTech Connect

    OLSSON,WILLIAM A.; HOLCOMB,DAVID J.

    2000-03-14

    Compaction bands are thin, tabular zones of grain breakage and reduced porosity that are found in sandstones. These structures may form due to tectonic stresses or as a result of local stresses induced during production of fluids from wells, resulting in barriers to fluid (oil, gas, water) movement in sandstone reservoirs. To gain insight into the formation of compaction bands the authors have produced them in the laboratory. Acoustic emission locations were used to define and track the thickness of compaction bands throughout the stress history during axisymmetric compression experiments. Narrow zones of intense acoustic emission, demarcating the boundaries between the uncompacted and compacted regions were found to develop. Unexpectedly, these boundaries moved at velocities related to the fractional porosity reduction across the boundary and to the imposed specimen compression stress. This appears to be a previously unrecognized, fundamental mode of deformation of a porous, granular material subjected to compressive loading with significant implications for the production of hydrocarbons.

  8. Modeling the Use of Mine Waste Rock as a Porous Medium Reservoir for Compressed Air Energy Storage

    NASA Astrophysics Data System (ADS)

    Donelick, R. A.; Donelick, M. B.

    2016-12-01

    We are studying the engineering and economic feasibilities of constructing Big Mass Battery (BiMBy) compressed air energy storage devices using some of the giga-tonnes of annually generated and historically produced mine waste rock/overburden/tailings (waste rock). This beneficial use of waste rock is based on the large mass (Big Mass), large pore volume, and wide range of waste rock permeabilities available at some large open pit metal mines and coal strip mines. Porous Big Mass is encapsulated and overlain by additional Big Mass; compressed air is pumped into the encapsulated pore space when renewable energy is abundant; compressed air is released from the encapsulated pore space to run turbines to generate electricity at the grid scale when consumers demand electricity. Energy storage capacity modeling: 1) Yerington Pit, Anaconda Copper Mine, Yerington, NV (inactive metal mine): 340 Mt Big Mass, energy storage capacity equivalent to 390k-710k home batteries of size 10 kW•h/charge, assumed 20% porosity, 50% overall efficiency. 2) Berkeley Pit, Butte Copper Mine, Butte, MT (inactive metal mine): 870 Mt Big Mass, energy storage capacity equivalent to 1.4M-2.9M home batteries of size 10 kW•h/charge, assumed 20% porosity, 50% overall efficiency. 3) Rosebud Mine, Colstrip, MT (active coal strip mine): 87 Mt over 2 years, energy storage capacity equivalent to 45k-67k home batteries of size 10 kW•h/charge, assumed 30% porosity, 50% overall efficiency. Encapsulating impermeable layer modeling: Inactive mine pits like Yerington Pit and Berkeley Pit, and similar active pits, have associated with them low permeability earthen material (silt and clay in Big Mass) at sufficient quantities to manufacture an encapsulating structure with minimal loss of efficiency due to leakage, a lifetime of decades or even centuries, and minimal need for the use of geomembranes. Active coal strip mines like Rosebud mine have associated with them low permeability earthen material such as

  9. Effect of isolated fractures on accelerated flow in unsaturated porous rock

    USGS Publications Warehouse

    Su, G.W.; Nimmo, J.R.; Dragila, M.I.

    2003-01-01

    Fractures that begin and end in the unsaturated zone, or isolated fractures, have been ignored in previous studies because they were generally assumed to behave as capillary barriers and remain nonconductive. We conducted a series of experiments using Berea sandstone samples to examine the physical mechanisms controlling flow in a rock containing a single isolated fracture. The input fluxes and fracture orientation were varied in these experiments. Visualization experiments using dyed water in a thin vertical slab of rock were conducted to identify flow mechanisms occurring due to the presence of the isolated fracture. Two mechanisms occurred: (1) localized flow through the rock matrix in the vicinity of the isolated fracture and (2) pooling of water at the bottom of the fracture, indicating the occurrence of film flow along the isolated fracture wall. These mechanisms were observed at fracture angles of 20 and 60 degrees from the horizontal, but not at 90 degrees. Pooling along the bottom of the fracture was observed over a wider range of input fluxes for low-angled isolated fractures compared to high-angled ones. Measurements of matrix water pressures in the samples with the 20 and 60 degree fractures also demonstrated that preferential flow occurred through the matrix in the fracture vicinity, where higher pressures occurred in the regions where faster flow was observed in the visualization experiments. The pooling length at the terminus of a 20 degree isolated fracture was measured as a function of input flux. Calculations of the film flow rate along the fracture were made using these measurements and indicated that up to 22% of the flow occurred as film flow. These experiments, apparently the first to consider isolated fractures, demonstrate that such features can accelerate flow through the unsaturated zone and should be considered when developing conceptual models.

  10. Geothermal Fluid Interaction with Mafic Rocks in Porous Media - AN Experimental and Reactive Transport Modeling Study

    NASA Astrophysics Data System (ADS)

    Stefansson, A.

    2013-12-01

    Reaction and reactive transport modeling is becoming an increasingly popular method to study fluid-rock interaction and fluid transport on small to large scales. In this study, fluid-rock experiments were carried out and the observations compared with the results of reaction and reactive transport models. The systems studied included fluid-rock interaction of olivine on one hand and basaltic glass on the other hand with dilute aqueous solutions containing CO2 at acid to neutral pH and temperatures from ambient to 250 °C. The experiments were conducted using batch type experiments in closed reactors and 1-D plug experiments in flow-through reactors and the solution chemistry, the reaction progress, secondary mineralization and porosity changes analyzed as a function of time. The reaction and 1-D reactive transport simulations were conducted with the aid of the PHREEQC program. For the simulations the thermodynamic database for mineral reactions was largely updated and the kinetics of mineral dissolution as well as mineral nucleation and crystal growth was incorporated. According to the experimental results and the reactive transport simulations, olivine and basaltic glass progressively dissolves forming secondary minerals and solutes that are partially transported out of them column (system). The exact reaction path was found to depend on solution composition and pH and reaction progress (time). The mass movement of the system at a particular steady state as well as porosity changes may be divided into three stages. Stage I is characterized by initial olivine or basaltic glass leaching, stage II is characterized by progressive mineral formation and decrease in porosity and stage III is characterized by remobilization of the previously formed secondary minerals and eventual increase in porosity. The reaction and reactive transport modeling was found to simulate reasonable the reaction path as a function of reaction time. However, exact mass movement and time

  11. Effect of pore pressure on the velocity of compressional waves in low-porosity rocks.

    NASA Technical Reports Server (NTRS)

    Todd, T.; Simmons, G.

    1972-01-01

    The velocity V sub p of compressional waves has been measured in rock samples of low porosity to confining pressures P sub c of 2 kb for a number of different constant pore pressures P sub p. An effective pressure defined by P sub e = P sub c-nP sub p, n less than or equal to 1, is found to be the determining factor in the behavior of V sub p rather than an effective pressure defined simply by the differential pressure Delta P = P sub c-P sub p. As pore pressure increases at constant effective pressure, the value of n increases and approaches 1, but as effective pressure increases at constant pore pressure, the value of n decreases. These observations are consistent with Biot's theory of the propagation of elastic waves in a fluid-saturated porous solid.

  12. Combined Geoelectrical and Georadar Measurement for State Characterization of porous Rock

    NASA Astrophysics Data System (ADS)

    Boerner, F. D.

    2006-05-01

    The state parameters volumetric pore water content and pore water composition influence geomechanical stability of near surface unconsolidated rock or soil. Changes of those characteristics can result in the instability of the rock and therefore in on set of a failure process. The geophysical monitoring of state parameters in space and time allows the assessment of compaction or soil water suction/pressure. The objective of the thereafter presented investigation was the quantitative determination of water saturation and water salinity using multimethod geophysical measurement. The application of only one geophysical method can give rise to gross uncertainties in the estimation of salinity or water saturation. The combination of a low frequency conductivity measurement (2 Hz) and a high frequency electromagnetic measurement (1 GHz) provides two petrophysical parameters: electrical conductivity and dielectric permittivity. Both parameters are strongly water saturation dependent and somewhat dependent on water salinity. A system of two nonlinear model-equations was used to determine salinity and saturation. An unique solution is possible in case of constant pore space structure. The experiments have been carried out on a rectangular designed sand box model and a hydraulically isolated sandstone block. Each of that has a size of 2m x 1m x 0.3 m. Three types of medium scale hydraulic experiments were monitored by multimethod geophysical measurements: - Water imbibition and drainage, - Displacement of water by density driven flow, - Displacement of water by forced convection 4-point electric conductivity measurement and radar transmission measurement have been carried out along several vertical profiles. The data were used to test the area of validity of the petrophysical model. The block model were divided into several descrete rock volumes. Water saturation and salinity were calculated for each single discrete rock volume. Independently water balance and hence the mean

  13. Training and Research on Probabilistic Hydro-Thermo-Mechanical Modeling of Carbon Dioxide Geological Sequestration in Fractured Porous Rocks

    SciTech Connect

    Gutierrez, Marte

    2013-05-31

    Colorado School of Mines conducted research and training in the development and validation of an advanced CO{sub 2} GS (Geological Sequestration) probabilistic simulation and risk assessment model. CO{sub 2} GS simulation and risk assessment is used to develop advanced numerical simulation models of the subsurface to forecast CO2 behavior and transport; optimize site operational practices; ensure site safety; and refine site monitoring, verification, and accounting efforts. As simulation models are refined with new data, the uncertainty surrounding the identified risks decrease, thereby providing more accurate risk assessment. The models considered the full coupling of multiple physical processes (geomechanical and fluid flow) and describe the effects of stochastic hydro-mechanical (H-M) parameters on the modeling of CO{sub 2} flow and transport in fractured porous rocks. Graduate students were involved in the development and validation of the model that can be used to predict the fate, movement, and storage of CO{sub 2} in subsurface formations, and to evaluate the risk of potential leakage to the atmosphere and underground aquifers. The main major contributions from the project include the development of: 1) an improved procedure to rigorously couple the simulations of hydro-thermomechanical (H-M) processes involved in CO{sub 2} GS; 2) models for the hydro-mechanical behavior of fractured porous rocks with random fracture patterns; and 3) probabilistic methods to account for the effects of stochastic fluid flow and geomechanical properties on flow, transport, storage and leakage associated with CO{sub 2} GS. The research project provided the means to educate and train graduate students in the science and technology of CO{sub 2} GS, with a focus on geologic storage. Specifically, the training included the investigation of an advanced CO{sub 2} GS simulation and risk assessment model that can be used to predict the fate, movement, and storage of CO{sub 2} in

  14. Extracting Pore and Fracture Parameters of Porous Rocks Using a Method Based on Digital Image Analysis

    NASA Astrophysics Data System (ADS)

    Song, Z.; Song, Y.

    2015-12-01

    The characterization of pore and fracture is an important part of regional hydrological survey. Traditional methods (e.g. mercury intrusion, porosimetry, and pressure pulse) can effectively determine the parameters of pore and fracture for high-permeability rocks. However, these methods tend to fail for low-permeability rocks, especially quartz sandstone and granite. Thus, this work presented a novel method to determine the parameters of pore and fracture by analyzing the digital image of the casting thin sections under a microscope. Firstly, the size of representative elementary image was obtained by calculating pore parameters of different scales of samples. Then the method based on representative elementary image analyzed the casting thin sections of sandstone with low permeability, low anisotropy, and high water-binding capacity, and determined the parameters such as porosity, round-hole rate, roundness. Besides, this method analyzed the casting thin sections of low-permeability granite from Beishan, Gansu, China to determine more parameters such as fracture rate, length-width ratio of fracture, direction angle, and roundness. Finally, these parameters determined by the method were compared with those by transient pressure pulse method. The comparison demonstrated that the presented method can determine more high-accuracy parameters than transient pressure pulse method. Key words: digital image analysis, casting thin sections, pore, fracture, parameters analysis

  15. 3D Modelisation of Monophasic Flow in Bimodal Porous Rocks: Darcy-Brinkman Solved by TRT Lattice-Boltzmann Method

    NASA Astrophysics Data System (ADS)

    Gland, N. F.; Talon, L.; Bauer, D.; Youssef, S.; Auradou, H.

    2010-12-01

    We present a numerical study of the flow field in complex geological porous media on the basis of 3D X-ray microtomography reconstructions of their microstructure using a Lattice-Boltzmann numerical method. Indeed LB method is now classicaly used to simulate Stockes flow in porous media. However, we are mainly interested in double porosity media as can often be found in reservoir rocks (e.g. carbonates), generally characterized by a macropore network (typical pore size of few µm to few tens of µm), a microporous matrix (typical pore size <µm), and impermeable grains. Thus, our principal goal is to evaluate the flow field in the macropores and in the microporous matrix as a function of their spatial arrangement and we will show that LB method can be successfully used to simulate such complex flow. A laboratory X-Ray microscanner scans cylindrical plugs of 5mm in diameter and delivers grey-level volumes (with sizes of 1000^3 voxels and a resolution of 3µm) to be segmented and labelled. The partitioning between macropores and microporous matrix is thus constrained by the system resolution; while the complex shapes of the macropores are well captured, the microporosity has to be treated as a single phase. A set of morphological operations is applied to the grey level volumes, in order to obtain a three phase's segmented volume. Flow modelling in bimodal porous media requires the use of specific boundaries conditions between the flows in the macropores and in the porous matrix (continuity of the velocity and the shear stress at the interface). This requires the extension of the Darcy's law with the Brinkman term. In order to solve for the flow field one needs to affect effective petrophysical properties to the microporous matrix (porosity φ_µ and permeability K_µ). The porosity φ_µ being estimated from the grey level images, the permeability K_µ is determined on the basis of an experimental K(φ) law representative of the microstructure of the microporous

  16. Mechanisms for trapping and mobilization of residual fluids during capillary-dominated three-phase flow in porous rock

    NASA Astrophysics Data System (ADS)

    Helland, J. O.; Jettestuen, E.

    2016-07-01

    We use a multiphase level set approach to simulate capillary-controlled motions of isolated fluid ganglia surrounded by two other continuous fluids (i.e., double displacements) during three-phase flow on 3-D porous rock geometries. Double displacements and three-phase snap-off mechanisms are closely related. Water snap-off on gas/oil interfaces can initiate double displacements that mobilize isolated oil ganglia in water-wet rock, but it can also terminate ongoing double displacements and trap oil in water. The multiphase level set approach allows for calculating the evolution of disconnected-phase pressure during the motion. In the events of pore filling by double displacement of oil ganglia, and water snap-off on gas/oil interfaces, we find that the local gas/oil capillary pressure drops, while local oil/water capillary pressure increases, by a similar magnitude as observed for the capillary pressure drops during single-pore filling events in dynamic pore-scale experiments of two-phase drainage. We also find that oil ganglia decrease their surface area, and achieve a more compact shape, when the gas/oil interfacial area decreases at the expense of increased oil/water interfacial area during double displacement. By comparison with similar two-phase gas/water simulations, we find that the level of the gas/water capillary pressure curves, including hysteresis loops, are smaller when a mobile, disconnected oil is present, which suggests double displacement of oil is more favorable than direct gas/water displacement. We also present cases in which phase trapping occurred in the three-phase simulations, but not in the corresponding two-phase simulations, supporting the view that more trapping is possible in three-phase flow.

  17. Quantitative model of vapor dominated geothermal reservoirs as heat pipes in fractured porous rock

    SciTech Connect

    Pruess, K.

    1985-03-01

    We present a numerical model of vapor-dominated reservoirs which is based on the well-known conceptual model of White, Muffler, and Truesdell. Computer simulations show that upon heat recharge at the base, a single phase liquid-dominated geothermal reservoir in fractured rock with low matrix permeability will evolve into a two-phase reservoir with B.P.D. (boiling point-for-depth) pressure and temperature profiles. A rather limited discharge event through cracks in the caprock, involving loss of only a few percent of fluids in place, is sufficient to set the system off to evolve a vapor-dominated state. The attributes of this state are discussed, and some features requiring further clarification are identified. 26 refs., 5 figs.

  18. Synchronization of dissolution and precipitation fronts during infiltration-driven replacement in porous rocks

    NASA Astrophysics Data System (ADS)

    Kondratiuk, Paweł; Tredak, Hanna; Ladd, Anthony J. C.; Szymczak, Piotr

    2015-04-01

    Coupled dissolution-precipitation reactions, where two minerals share a common ion, occur frequently in geological replacement; the reactions are driven by an inflow of precipitating secondary ions and an outflow of dissolved primary ions. Although crystallization pressure is frequently invoked to explain volume-preserving replacement, it cannot be operative if the chemical reactions lead to a loss of mineral volume; here the host rock that should confine the precipitating mineral is dissolving faster than the grains are growing. In this paper we propose two chemical mechanisms by which a rapid dissolution front and a slower precipitation front can be synchronized, and volume-for-volume replacement preserved. We analyze these mechanisms within the framework of reactive transport theory and show that morphological features observed in calcite replacement can be correlated with predictions of the models.

  19. Rupture Cascades in a Discrete Element Model of a Porous Sedimentary Rock

    NASA Astrophysics Data System (ADS)

    Kun, Ferenc; Varga, Imre; Lennartz-Sassinek, Sabine; Main, Ian G.

    2014-02-01

    We investigate the scaling properties of the sources of crackling noise in a fully dynamic numerical model of sedimentary rocks subject to uniaxial compression. The model is initiated by filling a cylindrical container with randomly sized spherical particles that are then connected by breakable beams. Loading at a constant strain rate the cohesive elements fail, and the resulting stress transfer produces sudden bursts of correlated failures, directly analogous to the sources of acoustic emissions in real experiments. The source size, energy, and duration can all be quantified for an individual event, and the population can be analyzed for its scaling properties, including the distribution of waiting times between consecutive events. Despite the nonstationary loading, the results are all characterized by power-law distributions over a broad range of scales in agreement with experiments. As failure is approached, temporal correlation of events emerges accompanied by spatial clustering.

  20. Rupture cascades in a discrete element model of a porous sedimentary rock.

    PubMed

    Kun, Ferenc; Varga, Imre; Lennartz-Sassinek, Sabine; Main, Ian G

    2014-02-14

    We investigate the scaling properties of the sources of crackling noise in a fully dynamic numerical model of sedimentary rocks subject to uniaxial compression. The model is initiated by filling a cylindrical container with randomly sized spherical particles that are then connected by breakable beams. Loading at a constant strain rate the cohesive elements fail, and the resulting stress transfer produces sudden bursts of correlated failures, directly analogous to the sources of acoustic emissions in real experiments. The source size, energy, and duration can all be quantified for an individual event, and the population can be analyzed for its scaling properties, including the distribution of waiting times between consecutive events. Despite the nonstationary loading, the results are all characterized by power-law distributions over a broad range of scales in agreement with experiments. As failure is approached, temporal correlation of events emerges accompanied by spatial clustering.

  1. The seismic properties of sintered glass-bead media: effects of thermal cracking and fluid saturation

    NASA Astrophysics Data System (ADS)

    Li, Y.; Jackson, I.; David, E.; Schmitt, D. R.

    2013-12-01

    The stiffness of rocks is significantly affected by the presence of cracks as well as pore fluids, the latter potentially increasing the effective stiffness of cracks. Reversible pore-fluid flow within the crack network, occurring during seismic wave propagation, may result in strongly frequency dependent seismic properties. Theoretical models for fluid flow induced seismic wave dispersion have been proposed but have so far not been subject to thorough experimental testing. Soda-lime-silica glass beads, of ~300 μm diameter were sintered near the glass transition temperature to produce a synthetic analogue for sedimentary rock with low porosity (~2%) and a simpler microstructure. Widely distributed cracks with uniformly low aspect ratio (~0.0007) and crack porosity ~0.2% were introduced by quenching heated cylindrical samples into liquid water at room temperature. Combined use of low-frequency (mHz-Hz) forced oscillation techniques at the Australian National University with ultrasonic pulse transmission methods (MHz) at the University of Alberta, is allowing a broadband measurement of seismic velocities and attenuation on a thermally cracked glass-bead sample. A recent upgrade of the data acquisition system on the apparatus for forced oscillation measurements is providing improved precision in determining shear and Young's moduli, measured at seismic frequencies, reveal a strong systematic variation with effective pressure (Peff=Pc-Pf) and some relaxation at longer oscillation periods tentatively attributed to fluid flow. Under water-saturated conditions, at low frequencies, both shear and Young's moduli are noticeably higher than under dry or argon-saturated conditions, possibly attributed to spatial restricted flow of water during forced-oscillation tests. Ongoing measurement of ultrasonic velocities should thus provide the 'intermediate' to 'high' frequency bounds on elastic moduli.

  2. Permeability Estimation of Porous Rock by Means of Fluid Flow Simulation and Digital Image Analysis

    NASA Astrophysics Data System (ADS)

    Winardhi, C. W.; Maulana, F. I.; Latief, F. D. E.

    2016-01-01

    Permeability plays an important role to determine the characteristics of how fluids flow through a porous medium which can be estimated using various methods. Darcy's law and the Kozeny-Carman equation are two of the most utilized methods in estimating permeability. In Darcy's law, permeability can be calculated by applying a pressure gradient between opposing sides of inlet-outlet of a certain direction. The permeability then depends on the fluid viscosity and the flowrate. The Kozeny-Carman equation is an empirical equation which depends on several parameters such as shape factor of the pore, tortuosity, specific surface area, and porosity to determine the permeability. For both methods, digital image obtained by means of Micro CT-Scan is used. In this research, the permeability estimation using the Darcy's law was conducted by simulating fluid flow through the digital image using Lattice Boltzmann Method (LBM). As for the Kozeny-Carman equation, digital image analysis was used to obtain the required parameters. Two Kozeny-Carman equations were used to calculate the permeability of the samples. The first equation (KC1) depends on pore shape factor, porosity, tortuosity, and specific surface area while the second equation (KC2) only depends on pore radius, porosity, and tortuosity. We investigate the methods by first testing on three simple pipe models which vary in the radii. By using the result from Darcy's law as a reference, we compare the results from the Kozeny-Carman equations. From the calculation, KC2 yield smaller difference to the reference. The three methods were then applied to the Fontainebleau sandstone to verify the previous result.

  3. Thermohydrologic Modeling: Coupling Navier-Stokes Models of Gas, Moisture, and Heat Flow in Underground Engineered Systems with Porous-Media Models in Fractured Rocks

    NASA Astrophysics Data System (ADS)

    Hao, Y.; Nitao, J. J.; Buscheck, T. A.; Sun, Y.; Lee, K. H.

    2004-12-01

    Combined free and porous flows occur in a wide range of natural and engineered systems such as coupled transport processes driven by underground-engineered systems. One potential application for modeling these coupled flow processes is related to the emplacement of heat-generating radioactive waste package in tunnels lying above the water table. This example involves the flow of gas and moisture in large open tunnel and gas- and liquid-phase flow in the surrounding fractured, porous rocks. This study aims to develop a method of coupling the Navier-Stokes equations and the Darcy's law to achieve a more rigorous representation of all major flow and transport processes in underground tunnels and surrounding fractured host-rocks. While the thermohydrologic (TH) processes in host-rocks are treated based on porous-medium Darcy-flow approximations, the Navier-Stokes modeling is applied to describe in-tunnel flow behaviors (natural convection, realistic gas/moisture movement, turbulent flow conditions, etc.). The governing equations are numerically solved by a finite-element scheme in the NUFT code. Some numerical simulation results shown in this presentation provide environmental conditions that engineered systems would experience, which, therefore, may be useful for engineered system design analysis and performance assessment. This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

  4. Mechanistic models of biofilm growth in porous media

    NASA Astrophysics Data System (ADS)

    Jaiswal, Priyank; Al-Hadrami, Fathiya; Atekwana, Estella A.; Atekwana, Eliot A.

    2014-07-01

    Nondestructive acoustics methods can be used to monitor in situ biofilm growth in porous media. In practice, however, acoustic methods remain underutilized due to the lack of models that can translate acoustic data into rock properties in the context of biofilm. In this paper we present mechanistic models of biofilm growth in porous media. The models are used to quantitatively interpret arrival times and amplitudes recorded in the 29 day long Davis et al. (2010) physical scale biostimulation experiment in terms of biofilm morphologies and saturation. The model pivots on addressing the sediment elastic behavior using the lower Hashin-Shtrikman bounds for grain mixing and Gassmann substitution for fluid saturation. The time-lapse P wave velocity (VP; a function of arrival times) is explained by a combination of two rock models (morphologies); "load bearing" which assumes the biofilm as an additional mineral in the rock matrix and "pore filling" which assumes the biofilm as an additional fluid phase in the pores. The time-lapse attenuation (QP-1; a function of amplitudes), on the other hand, can be explained adequately in two ways; first, through squirt flow where energy is lost from relative motion between rock matrix and pore fluid, and second, through an empirical function of porosity (φ), permeability (κ), and grain size. The squirt flow model-fitting results in higher internal φ (7% versus 5%) and more oblate pores (0.33 versus 0.67 aspect ratio) for the load-bearing morphology versus the pore-filling morphology. The empirical model-fitting results in up to 10% increase in κ at the initial stages of the load-bearing morphology. The two morphologies which exhibit distinct mechanical and hydraulic behavior could be a function of pore throat size. The biofilm mechanistic models developed in this study can be used for the interpretation of seismic data critical for the evaluation of biobarriers in bioremediation, microbial enhanced oil recovery, and CO2

  5. Pore Structure Model for Predicting Elastic Wavespeeds in Fluid-Saturated Sandstones

    NASA Astrophysics Data System (ADS)

    Zimmerman, R. W.; David, E. C.

    2011-12-01

    During hydrostatic compression, in the elastic regime, ultrasonic P and S wave velocities measured on rock cores generally increase with pressure, and reach asymptotic values at high pressures. The pressure dependence of seismic velocities is generally thought to be due to the closure of compliant cracks, in which case the high-pressure velocities must reflect only the influence of the non-closable, equant "pores". Assuming that pores can be represented by spheroids, we can relate the elastic properties to the pore structure using an effective medium theory. Moreover, the closure pressure of a thin crack-like pore is directly proportional to its aspect ratio. Hence, our first aim is to use the pressure dependence of seismic velocities to invert the aspect ratio distribution. We use a simple analytical algorithm developed by Zimmerman (Compressibility of Sandstones, 1991), which can be used for any effective medium theory. Previous works have used overly restrictive assumptions, such as assuming that the stiff pores are spherical, or that the interactions between pores can be neglected. Here, we assume that the rock contains an exponential distribution of crack aspect ratios, and one family of stiff pores having an aspect ratio lying somewhere between 0.01 and 1. We develop our model in two versions, using the Differential Scheme, and the Mori-Tanaka scheme. The inversion is done using data obtained in dry experiments, since pore fluids have a strong effect on velocities and tend to mask the effect of the pore geometry. This avoids complicated joint inversion of dry and wet data, such as done by Cheng and Toksoz (JGR, 1979). Our results show that for many sets of data on sandstones, we can fit very well the dry velocities. Our second aim is to predict the saturated velocities from our pore structure model, noting that at a given differential stress, the pore structure should be the same as for a dry test. Our results show that the Biot-Gassmann predictions always

  6. Time-dependent Deformation in Porous Rocks Driven by Chemo-mechanical Coupling

    NASA Astrophysics Data System (ADS)

    Meredith, P. G.; Brantut, N.; Heap, M. J.; Baud, P.

    2015-12-01

    We report results from triaxial deformation of porous sandstone and limestone conducted to determine the time-dependency of deformation. Experiments were run on water-saturated samples under constant differential stress (creep) conditions. In sandstone, the deformation is entirely brittle for all levels of stress and for all resulting strain rates. The strain rate during creep is very stress sensitive, with a change of only 20 MPa in differential stress producing three orders of magnitude change in strain rate. Failure occurs by localized shear faulting after an extended period of dilatant microcracking, as evidenced by the output of acoustic emissions. By contrast, the behaviour of limestone is more complex. At low effective pressure, the creep behavior is brittle and characterised by the same features as observed for sandstone; a decelerating phase of creep, followed by an inflection and then an accelerating creep phase leading to macroscopic failure. Similarly, only a small amount of inelastic strain is accommodated before failure, and P wave speeds measured throughout deformation decrease continuously, indicating a continuous increase in dilatant crack damage. At higher effective pressure, brittle creep still occurs, but the details of the time-dependent deformation behavior are quite different. First, the total amount of accumulated creep strain increases dramatically with decreasing strain rate, and no localized failure occurs even at these higher strains. Second, the rate of decrease in P wave speeds during deformation decreases with decreasing strain rate; indicating that less damage is accumulated per unit strain when the strain rate is lower. Third, complementary strain rate stepping experiments indicate that the deformation becomes more compactant at lower strain rates. Taken together, these observations suggest that rate-dependent compactive deformation mechanisms compete with dilatant subcritical crack growth during creep in limestone under low

  7. Effect of convective transport in porous media on the conditions of organic matter maturation and generation of hydrocarbons in trap rocks complexes

    NASA Astrophysics Data System (ADS)

    Yurie Khachay, Professor; Mindubaev, Mansur

    2016-04-01

    One of the main problems of the study of the intrusion thermal effects on the maturation of the organic matter is to estimate the volume, intensity, thermal effects of the intrusion and its redistribution in porous media by convection. A numerical algorithm for solving the problem of the developed convection in two-dimensional and three-dimensional models of the porous medium depending on the incline angle is developed. It is defined that the convective stability in the medium decreases with increasing incline angle. It was found that depending on the incline angle the structure of convection from many cells for a flat horizontal layer changes and it transfers to more elongated structures along the layer. It is shown that depending on the incline angles, invading sill and imbedding volume of the porous medium it can be realized either stationary or non-stationary convection that provides a principal different thermal conditions of hydrocarbons maturation in the motherboard porous medium. We give numerical examples of the influence of the incline angle on the flow structure inside the porous inclusion. By the stationary convection the volume of the boundary layers between the convective sells increases. That can lead to increasing of the part of motherboard rocks that are outer the temperature conditions of oil catalysis and as a consequence to the overestimation of the deposits.

  8. Rock Physics Characterization of Porous Media Containing Hydrates Formed Out of Solution: Tetrathydrofuran VS. Dissolved Methane

    NASA Astrophysics Data System (ADS)

    Schicks, J. M.; Rydzy, M. B.; Spangenberg, E.; Batzle, M. L.

    2012-12-01

    Methane hydrate formation in sediments from the dissolved gas phase is a tedious and time-consuming task, due to the relatively low solubility of methane in water. A number of studies on physical properties of hydrated sediments have been conducted on sediments containing tetrahydrofuran (THF) hydrates instead. The use of THF as a hydrate former is convenient as it forms hydrate at atmospheric pressure and relatively high temperatures of about 277 K. It is completely miscible in water, thus forms hydrate out solution and promises homogeneous synthesis of THF hydrate in sediment. The applicability of THF as a proxy for methane hydrate formed out of solution, however, has often been questioned. To better understand whether THF hydrates represent a legitimate proxy for methane hydrates formed out of solution, ultrasonic velocity and resistivity measurements were performed on hydrated Ottawa Sand F110 sand and glass bead samples in conjunction with imaging techniques, such as micro X-ray computed tomography (MXCT), and scanning electron microscopy (SEM). Thereby the tests were conducted on samples containing hydrates formed both, from methane dissolved in water and with the use of THF. The results show, that in terms of ultrasonic velocities, THF and methane hydrates exhibit the same trend. As the hydrate crystallized in the pore space, no increase in velocity was observed until a critical hydrate saturation of 35-50 percent was exceeded. On the other hand, the bulk electrical resistivity increased with increasing gas hydrate saturation. Comparison with current rock physics models suggested that the gas hydrate formed out of solution in both cases exhibits pore-filling/ load-bearing behavior, i.e. it suggests that the hydrate is formed away from the grains. This was supported through the imaging. This series of measurements provided the first direct comparison of THF and methane hydrates formed out of solution in terms of how their distribution and location in the pore

  9. Determining the concentration and distribution of arsenic deposits in rock matrices and porous media by X-ray difference microtomography

    NASA Astrophysics Data System (ADS)

    Peng, D.; Alsina, M.; Chen, C.; Keane, D.; Packman, A. I.; Gaillard, J.; Aubeneau, A. F.; Pasten, P. A.; Pizarro, G.

    2009-12-01

    Synchrotron-based high resolution X-ray microtomography was used to characterize arsenic (As) deposits within porous media. The distribution of arsenic was determined using difference tomography, where the X-rays used to image the sample were selected to be just above and below the As absorption edge at 11,853 eV. The difference tomograms have background noise from other minerals contained in the sample, local variation of X-ray beam intensity, and electronic noise associated with the data acquisition process. Image processing filters, such as windowing or adaptive filters derived from the Fast Fourier Transform (FFT) method, were employed to reduce background noise in the tomograms and enhance information on the arsenic deposits. These errors are generally larger in difference tomography than in conventional X-ray microtomography because this method requires operating at very specific X-ray energies (i.e., an edge of the element of interest), and this constraint makes it very difficult to obtain optimal contrast for tomographic reconstruction. In particular, the signal-to-noise ratio is often low in difference tomograms of geological samples having high background X-ray absorption. The relationship between As concentration and difference image intensity was evaluated using well defined As samples prepared in the laboratory, along with As-rich sinter deposits from El Tatio hydrothermal field and fluvial sediments from the Loa River downstream of El Tatio. This relationship is non-linear because of interactions between the different sources of error in the construction of the difference tomograms. As a result, the difference tomography method is relatively insensitive to bulk As concentrations, and instead primarily provides information on the distribution of regions of the sample that have high As concentrations, such as As-rich particles, precipitates, or evaporite deposits. Tomographic 3D reconstructions of the porous media and of the aggregate structure thus

  10. Limit state for gas pressurized homogenous and inhomogenous media and rock. [Mechanical effects of high gas pressure applied to a porous, but only slightly permeable surface of a rock

    SciTech Connect

    Protosenya, A.G.; Chernikov, A.K.; Shirkes, O.A.; Stavrogin, A.N.

    1982-11-01

    The limiting strength state of gas-pressurized rock is examined in this paper. In experiments, pores of rock specimens were filled with gas. Tests of the influence of pore pressure on the magitude of the limiting strength of coal were made. The structure of a gas-pressurized porous medium is defined. The strain process is seen to exert influence on the magnitude of the porosity of the limiting state of the rock. The limiting state for plastic fracture is derived. The system of equations for the theory of the limiting strength state under plastic deformation follows. The Coulomb plasticity condition is introduced. The system of equations in inhomogenous media is also studied. Finally, a few simple solutions--stress distribution around circular holes, the elastic plastic problem--are given, to be used as component parts of more complex solutions.

  11. Textural evidence for jamming and dewatering of a sub-surface, fluid-saturated granular flow

    NASA Astrophysics Data System (ADS)

    Sherry, T. J.; Rowe, C. D.; Kirkpatrick, J. D.; Brodsky, E. E.

    2011-12-01

    Sand injectites are spectacular examples of large-scale granular flows involving migration of hundreds of cubic meters of sand slurry over hundreds of meters to kilometers in the sub-surface. By studying the macro- and microstructural textures of a kilometer-scale sand injectite, we interpret the fluid flow regimes during emplacement and define the timing of formation of specific textures in the injected material. Fluidized sand sourced from the Santa Margarita Fm., was injected upward into the Santa Cruz Mudstone, Santa Cruz County, California. The sand injectite exposed at Yellow Bank Beach records emplacement of both hydrocarbon and aqueous sand slurries. Elongate, angular mudstone clasts were ripped from the wall rock during sand migration, providing evidence for high velocity, turbid flow. However, clast long axis orientations are consistently sub-horizontal suggesting the slurry transitioned to a laminar flow as the flow velocity decreased in the sill-like intrusion. Millimeter to centimeter scale laminations are ubiquitous throughout the sand body and are locally parallel to the mudstone clast long axes. The laminations are distinct in exposure because alternating layers are preferentially cemented with limonite sourced from later groundwater infiltration. Quantitative microstructural analyses show that the laminations are defined by subtle oscillations in grain alignment between limonite and non-limonite stained layers. Grain packing, size and shape distributions do not vary. The presence of limonite in alternating layers results from differential infiltration of groundwater, indicating permeability changes between the layers despite minimal grain scale differences. Convolute dewatering structures deform the laminations. Dolomite-cemented sand, a signature of hydrocarbon saturation, forms irregular bodies that cross-cut the laminations and dewatering structures. Laminations are not formed in the dolomite-cemented sand. The relative viscosity difference

  12. Seismic Absorption and Modulus Measurements in Porous Rocks in Lab and Field: Physical, Chemical, and Biological Effects of Fluids (Detecting a Biosurfactant Additive in a Field Irrigation Experiment)

    SciTech Connect

    Spetzler, Hartmut

    2006-05-01

    We have been exploring a new technology that is based on using low-frequency seismic attenuation data to monitor changes in fluid saturation conditions in two-fluid phase porous materials. The seismic attenuation mechanism is related to the loss of energy due to the hysteresis of resistance to meniscus movement (changes in surface tension, wettability) when a pore containing two fluids is stressed at very low frequencies (< 10 Hz). This technology has potential applications to monitoring changes in (1) leakage at buried waste sites, (2) contaminant remediation, and (3) flooding during enhanced petroleum recovery. We have concluded a three year field study at the Maricopa Agricultural Center site of the University of Arizona. Three sets of instruments were installed along an East-West line perpendicular to the 50m by 50m inigation site. Each set of instruments consisted of one three component seismometer and one tiltmeter. Microseisms and solid Earth-tides served as strain sources. The former have a power peak at a period of about 6 seconds and the tides have about two cycles per day. Installation of instruments commenced in late summer of 2002. The instruments operated nearly continuously until April 2005. During the fall of 2003 the site was irrigated with water and one year later with water containing 150 ppm of a biosurfactant additive. This biodegradable additive served to mimic a class of contaminants that change the surface tension of the inigation fluid. Tilt data clearly show tidal tilts superimposed on local tilts due to agricultural irrigation and field work. When the observed signals were correlated with site specific theoretical tilt signals we saw no anomalies for the water irrigation in 2003, but large anomalies on two stations for the surfactant irrigation in 2004. Occasional failures of seismometers as well as data acquisition systems contributed to less than continuous coverage. These data are noisier than the tilt data, but do also show possible

  13. A Transverse Dynamic Deflection Model for Thin Plate Made of Saturated Porous Materials

    NASA Astrophysics Data System (ADS)

    Feng-xi, Zhou; Xiao-lin, Cao

    2016-10-01

    In this article, a transverse dynamic deflection model is established for thin plate made of saturated porous materials. Based on the Biot's model for fluid-saturated porous media, using the Love-Kirchhoff hypothesis, the governing equations of transverse vibrations of fluid-saturated poroelastic plates are derived in detail, which take the inertial, fluid viscous, mechanical couplings, compressibility of solid, and fluid into account. The free vibration and forced vibration response of a simply supported poroelastic rectangular plate is obtained by Fourier series expansion method. Through numerical examples, the effect of porosity and permeability on the dynamic response, including the natural frequency, amplitude response, and the resonance areas is assessed.

  14. Comparative sound velocity measurements between porous rock and fully-dense material under crustal condition: The cases of Darley Dale sandstone and copper block

    NASA Astrophysics Data System (ADS)

    Kung, J.; Chien, Y. V.; Wu, W.; Dong, J.; Chang, Y.; Tsai, C.; Yang, M.; Wang, K.

    2012-12-01

    Previous studies showed that the voids and their geometry in the sedimentary rocks have great influence on the compressibility of rock, which reflects on its elastic velocities. Some models were developed to discuss the relations among velocity, porosity and void geometry. Therefore, the information of porosity, and void geometry and its distribution in rock is essential for understanding how the elastic properties of porous rocks affected by their poregeometry. In this study, we revisited a well-studied porous rock, Darley Dale sandstone, which has been studied by different groups with different purposes. Most of them are the deformation experiments. Different from previous studies, we measured the sound velocity of Darley dale sandstone under hydrostatic conditions. Also, we employed different techniques to investigate the pore geometry and porosity of Darley Dale sandstone to gain the insight of velocity changing behavior under the crustal conditions. Here, we measured a fully-dense copper block for a comparison. We performed X-ray CT scanning (XCT) to image the pore space of sandstone to construct the 3-D image of pore geometry, distribution and the pore size. The CT image data are allowed us to estimate the porosity of sandstone, too. One the other hand, the porosity of sample was measured using imbibitions method at ambient conditions and helium porosimeter at high pressure (up to 150 MPa). A set of specimens were cored from Darley Dale sandstone block. P and S wave velocities of specimens were measured at ambient conditions. We also performed high pressure velocity measurements on a selected rock specimen and a copper block up to 150 MPa under dry condition. Porosity of a set of rock specimens measured by imbibitions method was spanned from 6% to 15%, largely distributed within a range of 8%-11%. Compared the porosity obtained from three different techniques, imbibitions method, helium porosimeter and XCT, values from those measurements are in good agreement

  15. Modeling of viscoelastic properties of nonpermeable porous rocks saturated with highly viscous fluid at seismic frequencies at the core scale

    NASA Astrophysics Data System (ADS)

    Wang, Zizhen; Schmitt, Douglas R.; Wang, Ruihe

    2017-08-01

    A core scale modeling method for viscoelastic properties of rocks saturated with viscous fluid at low frequencies is developed based on the stress-strain method. The elastic moduli dispersion of viscous fluid is described by the Maxwell's spring-dash pot model. Based on this modeling method, we numerically test the effects of frequency, fluid viscosity, porosity, pore size, and pore aspect ratio on the storage moduli and the stress-strain phase lag of saturated rocks. And we also compared the modeling results to the Hashin-Shtrikman bounds and the coherent potential approximation (CPA). The dynamic moduli calculated from the modeling are lower than the predictions of CPA, and both of these fall between the Hashin-Shtrikman bounds. The modeling results indicate that the frequency and the fluid viscosity have similar effects on the dynamic moduli dispersion of fully saturated rocks. We observed the Debye peak in the phase lag variation with the change of frequency and viscosity. The pore structure parameters, such as porosity, pore size, and aspect ratio affect the rock frame stiffness and result in different viscoelastic behaviors of the saturated rocks. The stress-strain phase lags are larger with smaller stiffness contrasts between the rock frame and the pore fluid. The viscoelastic properties of saturated rocks are more sensitive to aspect ratio compared to other pore structure parameters. The results suggest that significant seismic dispersion (at about 50-200 Hz) might be expected for both compressional and shear waves passing through rocks saturated with highly viscous fluids.Plain Language SummaryWe develop a core scale modeling method to simulate the viscoelastic properties of <span class="hlt">rocks</span> saturated with viscous fluid at low frequencies based on the stress-strain method. The elastic moduli dispersion of viscous fluid is described by the Maxwell's spring-dash pot model. By using this modeling method, we numerically test</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10149969','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10149969"><span>Imaging techniques applied to the study of fluids in <span class="hlt">porous</span> media. Scaling up in Class 1 reservoir type <span class="hlt">rock</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tomutsa, L.; Brinkmeyer, A.; Doughty, D.</p> <p>1993-04-01</p> <p>A synergistic <span class="hlt">rock</span> characterization methodology has been developed. It derives reservoir engineering parameters from X-ray tomography (CT) scanning, computer assisted petrographic image analysis, minipermeameter measurements, and nuclear magnetic resonance imaging (NMRI). This <span class="hlt">rock</span> characterization methodology is used to investigate the effect of small-scale <span class="hlt">rock</span> heterogeneity on oil distribution and recovery. It is also used to investigate the applicability of imaging technologies to the development of scaleup procedures from core plug to whole core, by comparing the results of detailed simulations with the images ofthe fluid distributions observed by CT scanning. By using the <span class="hlt">rock</span> and fluid detailed data generated by imaging technology describe, one can verify directly, in the laboratory, various scaling up techniques. Asan example, realizations of <span class="hlt">rock</span> properties statistically and spatially compatible with the observed values are generated by one of the various stochastic methods available (fuming bands) and are used as simulator input. The simulation results were compared with both the simulation results using the true <span class="hlt">rock</span> properties and the fluid distributions observed by CT. Conclusions regarding the effect of the various permeability models on waterflood oil recovery were formulated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813696H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813696H"><span>Effects of <span class="hlt">Fluid</span> <span class="hlt">Saturation</span> on Gas Recovery from Class-3 Hydrate Accumulations Using Depressurization: Case Study of Yuan-An Ridge Site in Southwestern Offshore Taiwan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Yi-Jyun; Wu, Cheng-Yueh; Hsieh, Bieng-Zih</p> <p>2016-04-01</p> <p>Gas hydrates are crystalline compounds in which guest gas molecules are trapped in host lattices of ice crystals. In Taiwan, the significant efforts have recently begun to evaluate the reserves of hydrate because the vast accumulations of gas hydrates had been recognized in southwestern offshore Taiwan. Class-3 type hydrate accumulations are referred to an isolated hydrate layer without an underlying zone of mobile fluids, and the entire hydrate layer may be well within the hydrate stability zone. The depressurization method is a useful dissociation method for gas production from Class-3 hydrate accumulations. The dissociation efficiency is controlled by the responses of hydrate to the propagating pressure disturbance, and the pressure propagation is relating to the amount (or saturation) of the mobile fluid in pore space of the hydrate layer. The purpose of this study is to study the effects of <span class="hlt">fluid</span> <span class="hlt">saturation</span> on the gas recovery from a class-3 hydrate accumulation using depressurization method. The case of a class-3 hydrate deposit of Yuan-An Ridge in southwestern offshore Taiwan is studied. The numerical method was used in this study. The reservoir simulator we used to study the dissociation of hydrate and the production of gas was the STARS simulator developed by CMG, which coupled heat transfer, geo-chemical, geo-mechanical, and multiphase fluid flow mechanisms. The study case of Yuan-An Ridge is located in southwestern offshore Taiwan. The hydrate deposit was found by the bottom simulating reflectors (BSRs). The geological structure of the studied hydrate deposit was digitized to build the geological model (grids) of the case. The formation parameters, phase behavior data, <span class="hlt">rock</span> and fluid properties, and formation's initial conditions were assigned sequentially to grid blocks, and the completion and operation conditions were designed to wellbore blocks to finish the numerical model. The changes of reservoir pressure, temperature, saturation due to the hydrate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMNS31A1954T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMNS31A1954T"><span>A feasible research of <span class="hlt">rock</span> porosity and water saturation impact on audio-magnetotelluric propagation in <span class="hlt">porous</span> media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tian, Z.; Liu, J.</p> <p>2015-12-01</p> <p>Abstract: Although various factors have impact on the resistivity of subsurface <span class="hlt">rock</span> formation, in depth range of general electrical prospecting, the conductive actions of <span class="hlt">rocks</span> are basically realized relying on the aqueous solutions filled in the pores. Therefore, quantitatively studying the impact of the water level on <span class="hlt">rock</span> resistivity is important to analyze and classify strata, investigate the underground structures. In this research, we proposed a feasible research on building electric property <span class="hlt">rock</span> formation models with different porosity and water saturation based on theories of two-phase media. The propagation of audio-magnetotelluric (AMT) waves is simulated by using finite-difference (FD) scheme, and theoretic resistivity distribution is calculated on account of the response of AMT. According to a sequence of synthetic examples, through comparing and analyzing the simulated results with various porosity and water saturation respectively, we discuss the impact on layers resistivity while porosity and water saturation of <span class="hlt">rock</span> stratum are changing. The results shows the extent that the mentioned factors can have impact on the propagation of AMT waves. Key words: audio-magnetotelluric modeling, two-phase media, porosity, water saturation, finite-difference</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10159675','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10159675"><span>Geophysical and transport properties of reservoir <span class="hlt">rocks</span>. Final report for task 4: Measurements and analysis of seismic properties</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cook, N.G.W.</p> <p>1993-05-01</p> <p>The principal objective of research on the seismic properties of reservoir <span class="hlt">rocks</span> is to develop a basic understanding of the effects of <span class="hlt">rock</span> microstructure and its contained pore fluids on seismic velocities and attenuation. Ultimately, this knowledge would be used to extract reservoir properties information such as the porosity, permeability, clay content, <span class="hlt">fluid</span> <span class="hlt">saturation</span>, and fluid type from borehole, cross-borehole, and surface seismic measurements to improve the planning and control of oil and gas recovery. This thesis presents laboratory ultrasonic measurements for three granular materials and attempts to relate the microstructural properties and the properties of the pore fluids to P- and S-wave velocities and attenuation. These experimental results show that artificial <span class="hlt">porous</span> materials with sintered grains and a sandstone with partially cemented grains exhibit complexities in P- and S-wave attenuation that cannot be adequately explained by existing micromechanical theories. It is likely that some of the complexity observed in the seismic attenuation is controlled by details of the <span class="hlt">rock</span> microstructure, such as the grain contact area and grain shape, and by the arrangement of the grain packing. To examine these effects, a numerical method was developed for analyzing wave propagation in a grain packing. The method is based on a dynamic boundary integral equation and incorporates generalized stiffness boundary conditions between individual grains to account for viscous losses and grain contact scattering.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017HydJ..tmp..143L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017HydJ..tmp..143L"><span>Solute transport along a single fracture in a <span class="hlt">porous</span> <span class="hlt">rock</span>: a simple analytical solution and its extension for modeling velocity dispersion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Longcheng; Neretnieks, Ivars; Shahkarami, Pirouz; Meng, Shuo; Moreno, Luis</p> <p>2017-07-01</p> <p>A simple and robust solution is developed for the problem of solute transport along a single fracture in a <span class="hlt">porous</span> <span class="hlt">rock</span>. The solution is referred to as the solution to the single-flow-path model and takes the form of a convolution of two functions. The first function is the probability density function of residence-time distribution of a conservative solute in the fracture-only system as if the <span class="hlt">rock</span> matrix is impermeable. The second function is the response of the fracture-matrix system to the input source when Fickian-type dispersion is completely neglected; thus, the effects of Fickian-type dispersion and matrix diffusion have been decoupled. It is also found that the solution can be understood in a way in line with the concept of velocity dispersion in fractured <span class="hlt">rocks</span>. The solution is therefore extended into more general cases to also account for velocity variation between the channels. This leads to a development of the multi-channel model followed by detailed statistical descriptions of channel properties and sensitivity analysis of the model upon changes in the model key parameters. The simulation results obtained by the multi-channel model in this study fairly well agree with what is often observed in field experiments—i.e. the unchanged Peclet number with distance, which cannot be predicted by the classical advection-dispersion equation. In light of the findings from the aforementioned analysis, it is suggested that forced-gradient experiments can result in considerably different estimates of dispersivity compared to what can be found in natural-gradient systems for typical channel widths.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25158486','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25158486"><span>[Models for quantification of <span class="hlt">fluid</span> <span class="hlt">saturation</span> in two-phase flow system by light transmission method and its application].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Yan-Hong; Ye, Shu-Jun; Wu, Ji-Chun</p> <p>2014-06-01</p> <p>Based on light transmission method in quantification of liquid saturation and its application in two-phase flow system, two groups of sandbox experiments were set up to study the migration of gas or Dense Non-Aqueous Phase Liquids (DNAPLs) in water saturated <span class="hlt">porous</span> media. The migration of gas or DNAPL was monitored in the study. Two modified Light Intensity-Saturation (LIS) models for water/gas two-phase system were applied and verified by the experiment data. Moreover two new LIS models for NAPL/water system were developed and applied to simulate the DNAPL infiltration experiment data. The gas injection experiment showed that gas moved upward to the top of the sandbox in the form of 'fingering' and finally formed continuous distribution. The results of DNAPL infiltration experiment showed that TCE mainly moved downward as the result of its gravity, eventually formed irregular plume and accumulated at the bottom of the sandbox. The outcomes of two LIS models for water/gas system (WG-A and WG-B) were consistent to the measured data. The results of two LIS models for NAPL/water system (NW-A and NW-B) fit well with the observations, and Model NW-A based on assumption of individual drainage gave better results. It could be a useful reference for quantification of NAPL/water saturation in <span class="hlt">porous</span> media system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016CG.....91...33L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016CG.....91...33L"><span>The diffraction of Rayleigh waves by a <span class="hlt">fluid-saturated</span> alluvial valley in a poroelastic half-space modeled by MFS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Zhongxian; Liang, Jianwen; Wu, Chengqing</p> <p>2016-06-01</p> <p>Two dimensional diffraction of Rayleigh waves by a <span class="hlt">fluid-saturated</span> poroelastic alluvial valley of arbitrary shape in a poroelastic half-space is investigated using the method of fundamental solutions (MFS). To satisfy the free surface boundary conditions exactly, Green's functions of compressional (PI and PII) and shear (SV) wave sources buried in a <span class="hlt">fluid-saturated</span> poroelastic half-space are adopted. Next, the procedure for solving the scattering wave field is presented. It is verified that the MFS is of excellent accuracy and numerical stability. Numerical results illustrate that the dynamic response strongly depends on such factors as the incident frequency, the porosity of alluvium, the boundary drainage condition, and the valley shape. There is a significant difference between the diffraction of Rayleigh waves for the saturated soil case and for the corresponding dry soil case. The wave focusing effect both on the displacement and pore pressure can be observed inside the alluvial valley and the amplification effect seems most obvious in the case of higher porosity and lower frequency. Additionally, special attention should also be paid to the concentration of pore pressure, which is closely related to the site liquefaction in earthquakes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMMR13A2235S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMMR13A2235S"><span>Influence of Stress State, Stress Orientation, and <span class="hlt">Rock</span> Properties on the Development of Deformation-Band 'Ladder' Arrays in <span class="hlt">Porous</span> Sandstone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schultz, R. A.; Soliva, R.; Fossen, H.</p> <p>2013-12-01</p> <p>Deformation bands in <span class="hlt">porous</span> <span class="hlt">rocks</span> tend to develop into spatially organized arrays that display a variety of lengths and thicknesses, and their geometries and arrangements are of interest with respect to fluid flow in reservoirs. Field examples of deformation band arrays in layered clastic sequences suggest that the development of classic deformation band arrays, such as ladders and conjugate sets, and the secondary formation of through-going faults appear to be related to the physical properties of the host <span class="hlt">rock</span>, the orientation of stratigraphic layers relative to the far-field stress state, and the evolution of the local stress state within the developing array. We have identified several field examples that demonstrate changes in band properties, such as type and orientation, as a function of one or more of these three main factors. Normal-sense deformation-band arrays such as those near the San Rafael Swell (Utah) develop three-dimensional ladder-style arrays at a high angle to the maximum compression direction; these cataclastic shear bands form at acute angles to the maximum compression not very different from that of the optimum frictional sliding plane, thus facilitating the eventual nucleation of a through-going fault. At Orange quarry (France), geometrically conjugate sets of reverse-sense compactional shear bands form with angles to the maximum compression direction that inhibit fault nucleation within them; the bands in this case also form at steep enough angles to bedding that stratigraphic heterogeneities within the deforming formation were apparently not important. Two exposures of thrust-sense ladders at Buckskin Gulch (Utah) demonstrate the importance of host-<span class="hlt">rock</span> properties, bedding-plane involvement, and local stress perturbations on band-array growth. In one ladder, thrust-sense shear deformation bands nucleated along suitably oriented bedding planes, creating overprinting sets of compaction bands that can be attributed to layer properties and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005GeoJI.160..991C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005GeoJI.160..991C"><span>Amplitude of Biot's slow wave scattered by a spherical inclusion in a <span class="hlt">fluid-saturated</span> poroelastic medium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ciz, Radim; Gurevich, Boris</p> <p>2005-03-01</p> <p>Spatial heterogeneity of hydrocarbon reservoirs causes significant attenuation and dispersion of seismic waves due to wave-induced flow of the pore fluid between more compliant and less compliant areas. This paper investigates the interaction between a plane elastic wave in a poroelastic medium with a spherical inhomogeneity of another <span class="hlt">porous</span> material. The behaviour of both the inclusion and the background medium is described by the low-frequency variant of Biot's equations of poroelasticity with the standard boundary conditions at the inclusion surface, and for the inclusion size much smaller than the wavelength of the fast compressional wave. The scattering problem is formulated as a series expansion of displacements expressed in the spherical harmonics. The resulting scattered wavefield consists of the scattered normal compressional and shear waves and Biot's slow wave, which attenuates rapidly with distance from the inclusion and represents the main difference from the elastic case. This study concentrates on the attenuation effects caused by the mode conversion into Biot's slow wave. The solution obtained for Biot's slow wave is well described by the two terms of order n= 0 and n= 2 of the scattering series. The scattering amplitude for the term of order n= 0 is given by a simple expression. The full expression for the term of order n= 2 is very complicated, but can be simplified assuming that the amplitude of the scattered fast (normal) compressional and shear waves are well approximated by the solution of the equivalent elastic problem. This assumption yields a simple approximation for the amplitude of the scattered slow wave, which is accurate for a wide range of material properties and is sufficient for the analysis of the scattering amplitude as a function of frequency. In the low-frequency limit the scattering amplitude of the slow wave scales with ω3/2, and reduces to the asymptotic long-wavelength solution of Berryman (1985), which is valid for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1412229B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1412229B"><span>Characterization of the process of the strain localization in some <span class="hlt">porous</span> <span class="hlt">rocks</span> in plane strain condition using a new true triaxial apparatus</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Besuelle, P.</p> <p>2012-04-01</p> <p>Failure by strain localization is commonly observed in geomaterials. Generaly, experimental characterization of the localization in a <span class="hlt">porous</span> sandstone are performed with classical axisymmetric triaxial compression tests. The effect of the confining pressure is observed on several aspects: onset of localization, pattern of localization, porosity evolution inside bands, grain scale mechanisms of deformation. Complex patterns of localization can be observed at high confining pressure in the transition between the brittle and ductile regime, showing several deformation bands in the specimens ([1]). However the history (time evolution) of the localization is not accessible because the observations are post-mortem. Strain field measurement and evolution in time of the strain field are particularly useful to study the strain localization (initiation of the deformation bands) and the post-localization regime. Such tools have been developed for soils (e.g., sand specimens in plane strain condition [2] or in triaxial conditions using X-ray tomography [3]). Similar developments for <span class="hlt">rocks</span> are still difficult, especially because the pertinent confining pressure to reproduce in situ stresses are higher than for soils. We present here first results obtained in a new true triaxial apparatus that allows observation of the <span class="hlt">rock</span> specimen under loading and especially the complex development of deformation bands and faults. As for [4] and [5], the three principal stresses are different, however the intermediate stress is controlled in order to impose a plane strain condition (zero strain in this direction). Observation of a specimen under load is possible as one surface of the prismatic specimen, which is orthogonal to the plane strain direction, is in contact with a hard transparent window. The deformation of this surface is representative of the deformation in the whole specimen, up to and beyond strain localization. Therefore the evolution of the strain field in the sample can be</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1212436B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1212436B"><span>Experimental study of seismic attenuation in partially saturated <span class="hlt">porous</span> media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barrière, Julien; Bordes, Clarisse; Sénéchal, Pascale</p> <p>2010-05-01</p> <p>Nowadays, it is well admitted that hydrogeological properties of the <span class="hlt">porous</span> media (porosity, <span class="hlt">fluid</span> <span class="hlt">saturation</span> and permeability) can influence seismic properties. In geophysics, the major theory which links hydrogeological and seismic parameters is poroelasticity proposed by Biot (1956). The Biot relaxation process is due to the relative displacement of fluid in comparison to the solid which causes a significant attenuation of seismic waves, notably in unconsolidated medium. In partially saturated medium, pore fluids are considered as a perfect mixture and so called 'effective fluid'. However, in more consolidated <span class="hlt">rocks</span>, the Biot theory is not sufficient to explain the attenuation level as measured from field seismic and sonic log data. In the last decade, some authors provide new theories to understand the attenuation caused by the interaction of the different fluids. Most experiments are done in the ultrasonic frequency range, where sources of attenuation (like scattering or local fluid flow) are different as in the low frequency range where the wavelength is greater than heterogeneities size. In this way, we propose a forward-looking experiment with the use of a vertical impulsionnal seismic source which have a strong amplitude spectrum ranging from 100Hz to 8kHz. We study three different unconsolidated <span class="hlt">porous</span> media at atmospheric pressure: fine-grained sand, coarsed-grained sand and coarse gravel. Water content is measured with a calibrated capacitance probe and temperature effects are corrected. Seismic wave propagation is recorded by piezoelectric accelerometers designed for frequencies below 10kHz. The water injection is done by imbibition. We propose to analyse the attenuation in the [100Hz-1.5kHz] frequency range for the studied media with various water saturation levels. The attenuation varies according to the <span class="hlt">porous</span> medium and the water content and appears more significant at dry condition and at high saturation level. The weak cohesion at dry condition</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000JCHyd..46..265K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000JCHyd..46..265K"><span>Multispectral image analysis method to determine dynamic <span class="hlt">fluid</span> <span class="hlt">saturation</span> distribution in two-dimensional three-fluid phase flow laboratory experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kechavarzi, C.; Soga, K.; Wiart, P.</p> <p>2000-12-01</p> <p>The need for measuring dynamic <span class="hlt">fluid</span> <span class="hlt">saturation</span> distribution in multi-dimensional three-fluid phase flow experiments is hampered by lack of appropriate techniques to monitor full field transient flow phenomena. There is no conventional technique able to measure dynamic three-fluid phase saturation at several array points of the flow field at the same time. A multispectral image analysis technique was developed to determine dynamic NAPL, water and air saturation distribution in two-dimensional three-fluid phase laboratory experiments. Using a digital near-infrared camera, images of sand samples with various degrees of NAPL, water and air saturation were taken, under constant lighting conditions and within three narrow spectral bands of the visible and near-infrared spectrum. It was shown that the optical density defined for the reflected luminous intensity was a linear function of the NAPL and the water saturation for each spectral band and for any two and three-fluid phase systems. This allowed the definition of dimensionless lump reflection coefficients for the NAPL and the water phase within each spectral band. Consequently, at any given time, two images taken within two different spectral bands provided two linear equations which could be solved for the water and the NAPL saturation. The method was applied to two-dimensional three-phase flow experiments, which were conducted to investigate the migration and the distribution of LNAPL in the vadose zone. The method was used to obtain continuous, quantitative and dynamic full field mapping of the NAPL saturation as well as the variation of the water and the air saturation during NAPL flow. The method provides a non-destructive and non-intrusive tool for studying multiphase flow for which rapid changes in <span class="hlt">fluid</span> <span class="hlt">saturation</span> in the entire flow domain is difficult to measure using conventional techniques.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11..543B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11..543B"><span>Models of <span class="hlt">fluid</span> <span class="hlt">saturated</span> zones according magnetotellurics and seismics data on Tien-Shan crust and mantle along transect MANAS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bataleva, E.; Rybin, A.; Batalev, V.; Matyukov, V.</p> <p>2009-04-01</p> <p>Recognized as one of the highest, youngest, and most active orogenic systems on the Earth the Tien Shan is situated internal to the Eurasian continent. New deep seismic data acquired from 2004 to 2007 constitute an -400 km lithospheric transect located from the northwestern Tarim Basin in China to the northern Tien Shan in Kyrgyzstan. This seismic profile consists of 40 seismic stations "Quanterra" containing STS-2 (Streckeisen, Switzerland) and CMG - 3T (Güralp Systems Ltd) broadband seismic receivers. Registration of the seismic data in each station was conducted with sampling frequency of 40 Hz. Time service based on GPS clock was applied on each station. Average distance between the seismic stations along the profile is 10-15 km. Observations were held on 30 stations in Kyrgyzstan and on 10 of them in China. As a result of seismic investigations wave speeds cross-section was calculated. A 450 km long north-south magnetotelluric profile spanning the Tien Shan from Kazakhstan to western China reveals lateral variations in the resistivity of the Earth crust and mantle lithosphere to depths of 140 km. MT profile consisting of 19 long period MT soundings (20-20,000 s periods) were combined with 30 broadband stations (0.1-1600 s periods). Broadband measurements (0.001-100 s periods) were also acquired at the 14 long period sites in Kazakhstan and Kyrgyzstan. [Bielinski, et al 2003] Conductivity changes of up to one order of magnitude are a result from variations in temperature or composition, or both. Previous magneto telluric (MT) studies [Trapeznikov et al., 1997] partly show that some low velocity layers also have low resistivity, lending support to the fluid hypothesis. Studies of wave speeds reveal sections of the crust that have pronounced low velocity zones in the thicker portions of the crust which are attributed to crustal metasomatism [Ghose et al., 1998] or fluid filled fractures in pervasively deformed <span class="hlt">rocks</span> [Vinnik et al., 2002]. Comparing an obtained</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeoJI.202..871H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeoJI.202..871H"><span>Non-linear behaviour of electrical parameters in <span class="hlt">porous</span>, water-saturated <span class="hlt">rocks</span>: a model to predict pore size distribution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hallbauer-Zadorozhnaya, Valeriya; Santarato, Giovanni; Abu Zeid, Nasser</p> <p>2015-08-01</p> <p>In this paper, two separate but related goals are tackled. The first one is to demonstrate that in some saturated <span class="hlt">rock</span> textures the non-linear behaviour of induced polarization (IP) and the violation of Ohm's law not only are real phenomena, but they can also be satisfactorily predicted by a suitable physical-mathematical model, which is our second goal. This model is based on Fick's second law. As the model links the specific dependence of resistivity and chargeability of a laboratory sample to the injected current and this in turn to its pore size distribution, it is able to predict pore size distribution from laboratory measurements, in good agreement with mercury injection capillary pressure test results. This fact opens up the possibility for hydrogeophysical applications on a macro scale. Mathematical modelling shows that the chargeability acquired in the field under normal conditions, that is at low current, will always be very small and approximately proportional to the applied current. A suitable field test site for demonstrating the possible reliance of both resistivity and chargeability on current was selected and a specific measuring strategy was established. Two data sets were acquired using different injected current strengths, while keeping the charging time constant. Observed variations of resistivity and chargeability are in agreement with those predicted by the mathematical model. These field test data should however be considered preliminary. If confirmed by further evidence, these facts may lead to changing the procedure of acquiring field measurements in future, and perhaps may encourage the design and building of a new specific geo-resistivity meter. This paper also shows that the well-known Marshall and Madden's equations based on Fick's law cannot be solved without specific boundary conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813732P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813732P"><span>Numerical investigation of the hydro-mechanical contribution to seismic attenuation in damaged <span class="hlt">rocks</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pollmann, Nele; Jänicke, Ralf; Renner, Jörg; Steeb, Holger</p> <p>2016-04-01</p> <p>The investigation of hydro-mechanical processes, in particular the modeling of seismic waves in fractured <span class="hlt">porous</span> media, is essential for the physical interpretation of data obtained from seismic exploration. Here, we specifically investigate attenuation processes in <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> <span class="hlt">rock</span> containing fracture networks to identify effective hydro-mechanical properties by numerical simulation. The main purpose of this work is the characterization of the overall hydro-mechanical properties by computational homogenization. We determine an effective Skempton coefficient by investigating the fluid pressure and the solid displacement of the skeleton saturated by compressible fluids. Fracture networks are stochastically generated to mimic geological in-situ situations. The fractures are approximated as ellipses with aspect ratios up to 1/100, i.e. they constitute thin and long hydraulic conduits with high permeabilities. Simulations are designed on the material scale with and without conservation of fluid mass in the control volume. Using computational homogenization approaches, we define an effective Skempton coefficient. A range of fracture networks with different characteristic properties is studied for different varieties of fractures. On the material scale we find strongly heterogeneous pressure propagation in the fracture network and the surrounding <span class="hlt">rock</span>, respectively. The pressure diffusion is much faster in the fracture network than in the matrix, rendering the macroscopic hydro-mechanical behavior strongly time dependent. The effective Skempton coefficient converges to an ensemble-specific instantaneous value and to 1 for long-time studies. The ultimate objective of our study is to evaluate whether constraints on the structure of fracture networks can be deduced from observations of attenuation and its frequency dependence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.V22H..05N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.V22H..05N"><span>Excess Olivine and Positive FeO-MgO Trend in Bulk-<span class="hlt">rock</span> Abyssal Peridotites as a Consequence of <span class="hlt">Porous</span> Melt Migration Beneath Ocean Ridges</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Niu, Y.</p> <p>2003-12-01</p> <p>Abyssal peridotites (AP) are mantle melting residues for mid-ocean ridge basalts (MORB) [1-4]. Recent studies [5-8] have confirmed the complementary relationship between MORB and AP, but also revealed the hidden complexities in these peridotites such as olivine addition [5-7] and melt refertilization [7,9,10]. These same studies [5,6] have immediately excited serious debates on AP petrogenesis [11-15]. These debates are stimulating and healthy towards an improved understanding of ocean ridge magmatic processes. However, a straightforward interpretation [5,6] has been widely misunderstood because of the influence of [13]. A clarification is necessary. Niu, Langmuir and Kinzler [5] showed that a positive FeO-MgO trend exists in bulk-<span class="hlt">rock</span> AP samples reconstructed using mineral modes and compositions [3,4]. Such a positive trend is inconsistent with AP being simple melting residues, but consistent with AP being melting residues plus excess olivine [5,6]. Using their site averages of reconstructed bulk-<span class="hlt">rock</span> AP data, Baker and Beckett [13] countered that the positive FeO-MgO correlation by Niu et al. [5] is an artifact and there is no evidence for significant olivine accumulation in AP. The clarification here includes the following valid statements: (1) the site averages by [13] simply cannot be derived from their own unaveraged data; (2) the unaveraged data by [13], as expected, do show a positive FeO-MgO trend as shown by [5,6]; (3) the positive FeO-MgO trend is not an artifact as this trend is also clear in the unaveraged data of [13]; (4) excess olivine is already evident in the original modal data [3,4]; and (5) olivine addition is observed petrographically [7]. Therefore, the positive FeO-MgO trend defined by bulk-<span class="hlt">rock</span> AP samples is characteristic of AP. Addition of olivine in AP is a consequence of cooling of ascending melts migrating through advanced residues in the "cold" thermal boundary layer beneath ocean ridges [5,6]. This is consistent with bulk-<span class="hlt">rock</span> trace</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APhy...58..708Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APhy...58..708Z"><span>Study of acoustic radiation during air stream filtration through a <span class="hlt">porous</span> medium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zaslavskii, Yu. M.; Zaslavskii, V. Yu.</p> <p>2012-11-01</p> <p>The paper presents results of laboratory experiments on studying the characteristics of acoustic emission generated by a flow of compressed air, which is filtered by <span class="hlt">porous</span> pumice samples with and without partial <span class="hlt">fluid</span> <span class="hlt">saturation</span>. The construction features of the laboratory setup and details of the experiments are described. <span class="hlt">Porous</span> samples with dry and partially fluid-filled pores are used. The visual patterns of the acoustic emission spectrum, which occurs under stationary filtration of the compressed air, are presented, and its amplitude-frequency distribution characteristic for different sample porosities and different degrees of their <span class="hlt">fluid</span> <span class="hlt">saturation</span> is shown. It is demonstrated that the relaxation times of the emission noise level differ. This is revealed during the sharp elimination of the drop in pressure from such samples, i.e., in the nonstationary filtration mode.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4991259','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4991259"><span>Homogenization of two fluid flow in <span class="hlt">porous</span> media</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Daly, K. R.; Roose, T.</p> <p>2015-01-01</p> <p>The macroscopic behaviour of air and water in <span class="hlt">porous</span> media is often approximated using Richards' equation for the <span class="hlt">fluid</span> <span class="hlt">saturation</span> and pressure. This equation is parametrized by the hydraulic conductivity and water release curve. In this paper, we use homogenization to derive a general model for saturation and pressure in <span class="hlt">porous</span> media based on an underlying periodic <span class="hlt">porous</span> structure. Under an appropriate set of assumptions, i.e. constant gas pressure, this model is shown to reduce to the simpler form of Richards' equation. The starting point for this derivation is the Cahn–Hilliard phase field equation coupled with Stokes equations for fluid flow. This approach allows us, for the first time, to rigorously derive the water release curve and hydraulic conductivities through a series of cell problems. The method captures the hysteresis in the water release curve and ties the macroscopic properties of the <span class="hlt">porous</span> media with the underlying geometrical and material properties. PMID:27547073</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JAG...104...75Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JAG...104...75Z"><span>Finite difference modeling of ultrasonic propagation (coda waves) in digital <span class="hlt">porous</span> cores with un-split convolutional PML and rotated staggered grid</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Yan; Fu, Li-Yun; Zhang, Luxin; Wei, Wei; Guan, Xizhu</p> <p>2014-05-01</p> <p>Ultrasonic wave propagation in heterogeneous <span class="hlt">porous</span> cores under laboratory studies is an extremely complex process involved with strong scattering by microscale heterogeneous structures. The resulting coda waves, as an index to measure scattering attenuation, are recorded as continuous waveforms in the tail portion of wavetrains. Because of the contamination of reflections from the side ends and reverberations between the sample surfaces, it is difficult to extract pure coda waves from ultrasonic measurements for the estimation of the P- and S-coda attenuation quality factors. Comparisons of numerical and experimental ultrasonic wave propagation in heterogeneous <span class="hlt">porous</span> cores can give important insight into understanding the effect of boundary reflections on the P- and S-codas in the laboratory experiment. It challenges numerical modeling techniques by three major issues: the creation of a digital core model to map heterogeneous <span class="hlt">rock</span> properties in detail, the perfect simulation with a controllable and accurate absorbing boundary, and overcoming the numerical dispersions resulting from high-frequency propagation and strong heterogeneity in material. A rotated staggered-grid finite-difference method of Biot's poroelastic equations is presented with an unsplit convolutional perfectly matched layer (CPML) absorbing boundary to simulate poroelastic wave propagation in isotropic and <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> media. The contamination of boundary reflections on coda waves is controlled by the CPML absorbing coefficients for the comparison between numerical and experimental ultrasonic waveforms. Numerical examples with a digital <span class="hlt">porous</span> core demonstrate that the boundary reflections contaminate coda waves seriously, causing much larger coda quality factors and thus underestimating scattering attenuation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015IzPSE..51...70B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015IzPSE..51...70B"><span>The response of <span class="hlt">fluid-saturated</span> reservoirs to lunisolar tides: Part 1. Background parameters of tidal components in ground displacements and groundwater level</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Besedina, A. N.; Vinogradov, E. A.; Gorbunova, E. M.; Kabychenko, N. V.; Svintsov, I. S.; Pigulevskiy, P. I.; Svistun, V. K.; Shcherbina, S. V.</p> <p>2015-01-01</p> <p>The first part of this work is dedicated to the response of different-age structures to lunisolar tides, which can be considered as a sounding signal for monitoring the state of <span class="hlt">fluid-saturated</span> reservoirs. The complex approach to processing the data obtained at the testing sites of the Institute of Geosphere Dynamics of the Russian Academy of Sciences, Institute of Geophysics of the National Academy of Sciences of Ukraine, and KIEV station of the IRIS seismic network is applied for recognizing the tides against the hydrogeological, barometric, and seismic series. The comparative analysis of the experimental and theoretical values of the diurnal and semidiurnal tidal components in the time series of ground displacements is carried out. The tidal variations in the groundwater level are compared with the tidal components revealed in the ground displacement of the different-age structure of the Moscow Basin and Ukrainian Shield, which are parts of the East European artesian region. The differences in the tidal responses of the groundwater level and ground displacement probably suggest that the state of the massif is affected by certain additional factors associated, e.g., with the passage of earthquake-induced seismic waves and the changes in the hydrogeodynamic environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.G32C..06S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.G32C..06S"><span>When is the strain in the meter the same as that in the <span class="hlt">rock</span>?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Segall, P.; Jónsson, S.; Ágústsson, K.</p> <p>2003-12-01</p> <p>Borehole strainmeters are a valuable tool for monitoring crustal deformation and an important component of the Plate Boundary Observatory (PBO). One type, the dilatometer, measures the volumetric strain; three component strainmeters measure the dilatation and two in-plane shear strains. Borehole strainmeters are emplaced in <span class="hlt">porous</span> <span class="hlt">fluid</span> <span class="hlt">saturated</span> <span class="hlt">rock</span>. Pore-fluid flow induces strain, however there is no fluid exchange with the strainmeter. Thus, the dilatation measured by the strainmeter is the same as that in the <span class="hlt">rock</span> only when the <span class="hlt">rock</span> remains undrained. Assuming that the <span class="hlt">rock</span> is homogeneous and isotropic, the instrumental dilatation Δ inst is given by Δ inst = C1 (Δ ∞ - C2 p∞ ), where Δ ∞ and p∞ are strain and pore pressure far from the borehole, and C1 and C2 depend on poroelastic <span class="hlt">rock</span> properties; C1 = [{1-(1+ α )ν u}]/[{1-(1+ α )ν }], C2 = [{3(1+α )(ν u - ν )}]/[{2μ B(1+ν u)}], and ν , ν u are the drained and undrained Poisson's ratios, μ is shear modulus, B is Skempton's coefficient, and α measures the vertical strain sensitivity of the instrument. This predicts that increases in pore-pressure, due for example to rainfall, cause a contractional strain. A large rainfall event in south Iceland raised water levels by 1-2 meters (10 - 20 kPa). Assuming ν u = 0.33, ν = 0.25, B = 0.7, μ = 1010 Pa we predict contractions of order 180 nanostrain, in reasonable agreement with 4 of the 5 dilatometers in the area. Postseismic strain in the <span class="hlt">rock</span> is expected to increase as the induced pore pressure gradients relax. However, a dilatometer ˜ 3 \\ km from a Mw 6.5 earthquake in the South Iceland Seismic Zone shows a postseismic strain change opposite in sign to the coseismic response. { Rice and Cleary, Rev. Geophys.,} [1976] give the solution for two-dimensional edge dislocation in a poroelastic medium. From their results and the theory described above, we predict that the dilatation recorded by a strainmeter will be time invariant! This despite</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JAG...135...67J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JAG...135...67J"><span>A novel high-pressure vessel for simultaneous observations of seismic velocity and in situ CO2 distribution in a <span class="hlt">porous</span> <span class="hlt">rock</span> using a medical X-ray CT scanner</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jiang, Lanlan; Nishizawa, Osamu; Zhang, Yi; Park, Hyuck; Xue, Ziqiu</p> <p>2016-12-01</p> <p>Understanding the relationship between seismic wave velocity or attenuation and CO2 saturation is essential for CO2 storage in deep saline formations. In the present study, we describe a novel upright high-pressure vessel that is designed to keep a <span class="hlt">rock</span> sample under reservoir conditions and simultaneously image the entire sample using a medical X-ray CT scanner. The pressure vessel is composed of low X-ray absorption materials: a carbon-fibre-enhanced polyetheretherketone (PEEK) cylinder and PEEK vessel closures supported by carbon-fibre-reinforced plastic (CFRP) joists. The temperature was controlled by a carbon-coated film heater and an aramid fibre thermal insulator. The assembled sample cell allows us to obtain high-resolution images of <span class="hlt">rock</span> samples during CO2 drainage and brine imbibition under reservoir conditions. The <span class="hlt">rock</span> sample was oriented vertical to the rotation axis of the CT scanner, and seismic wave paths were aligned parallel to the rotation axis to avoid shadows from the acoustic transducers. The reconstructed CO2 distribution images allow us to calculate the CO2 saturation in the first Fresnel zone along the ray path between transducers. A robust relationship between the seismic wave velocity or attenuation and the CO2 saturation in <span class="hlt">porous</span> <span class="hlt">rock</span> was obtained from experiments using this pressure vessel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRB..121.6698R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRB..121.6698R"><span>Numerical upscaling in 2-D heterogeneous poroelastic <span class="hlt">rocks</span>: Anisotropic attenuation and dispersion of seismic waves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rubino, J. Germán.; Caspari, Eva; Müller, Tobias M.; Milani, Marco; Barbosa, Nicolás. D.; Holliger, Klaus</p> <p>2016-09-01</p> <p>The presence of stiffness contrasts at scales larger than the typical pore sizes but smaller than the predominant seismic wavelengths can produce seismic attenuation and velocity dispersion in <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> <span class="hlt">rocks</span>. This energy dissipation mechanism is caused by wave-induced fluid pressure diffusion among the different components of the probed geological formations. In many cases, heterogeneities have elongated shapes and preferential orientations, which implies that the overall response of the medium is anisotropic. In this work, we propose a numerical upscaling procedure that permits to quantify seismic attenuation and phase velocity considering fluid pressure diffusion effects as well as generic anisotropy at the sample's scale. The methodology is based on a set of three relaxation tests performed on a 2-D synthetic <span class="hlt">rock</span> sample representative of the medium of interest. It provides a complex-valued frequency-dependent equivalent stiffness matrix through a least squares procedure. We also derive an approach for computing various poroelastic fields associated with the considered sample in response to the propagation of a seismic wave with arbitrary incidence angle. Using this approach, we provide an energy-based estimation of seismic attenuation. A comprehensive numerical analysis indicates that the methodology is suitable for handling complex media and different levels of overall anisotropy. Comparisons with the energy-based estimations demonstrate that the dynamic-equivalent viscoelastic medium assumption made by the numerical upscaling procedure is reasonable even in the presence of high levels of overall anisotropy. This work also highlights the usefulness of poroelastic fields for the physical interpretation of seismic wave phenomena in strongly heterogeneous and complex media.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.3893L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.3893L"><span>Direct laboratory observation of fluid distribution and its influence on acoustic properties of patchy saturated <span class="hlt">rocks</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lebedev, M.; Clennell, B.; Pervukhina, M.; Shulakova, V.; Mueller, T.; Gurevich, B.</p> <p>2009-04-01</p> <p><span class="hlt">Porous</span> <span class="hlt">rocks</span> in hydrocarbon reservoirs are often saturated with a mixture of two or more fluids. Interpretation of exploration seismograms requires understanding of the relationship between distribution of the fluids patches and acoustic properties of <span class="hlt">rocks</span>. The sizes of patches as well as their distribution affect significantly the seismic response. If the size of the fluid patch is smaller than the diffusion wavelength then pressure equilibration is achieved and the bulk modulus of the <span class="hlt">rock</span> saturated with a mixture is defined by the Gassmann equations (Gassmann, 1951) with the saturation-weighted average of the fluid bulk modulus given by Wood's law (Wood, 1955, Mavko et al., 1998). If the fluid patch size is much larger than the diffusion wavelength then there is no pressure communication between different patches. In this case, fluid-flow effects can be neglected and the overall <span class="hlt">rock</span> may be considered equivalent to an elastic composite material consisting of homogeneous parts whose properties are given by Gassmann theory with Hill's equation for the bulk modulus (Hill, 1963, Mavko et al., 1998). At intermediate values of <span class="hlt">fluid</span> <span class="hlt">saturation</span> the velocity-saturation relationship is significantly affected by the fluid patch distribution. In order to get an improved understanding of factors influencing the patch distribution and the resulting seismic wave response we performed simultaneous measurements of P-wave velocities and <span class="hlt">rock</span> sample CT imaging. The CT imaging allows us to map the fluid distribution inside <span class="hlt">rock</span> sample during saturation (water imbibition). We compare the experimental results with theoretical predictions. In this paper we will present results of simultaneous measurements of longitudinal wave velocities and imaging mapping of fluid distribution inside <span class="hlt">rock</span> sample during sample saturation. We will report results of two kinds of experiments: "dynamic" and "quasi static" saturation. In both experiments Casino Cores Otway Basin sandstone, Australia core</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA185038','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA185038"><span>Development of a New Method of Measuring the Characteristic Impedance and Complex Wave Number of a <span class="hlt">Porous</span> Acoustic Material.</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1987-06-01</p> <p>4! / D 0 ra CL (7 L n~ J &~~P~~MA, APPENDIX A .’ETHOD OF SOLUTION OF THE DISPERSION RELATION AND ITS IMPLEMENTATION The mehtod used to find the roots...Constant and Characteristic Impedance of <span class="hlt">Porous</span> Acoustical Material", J . Acoust. Soc. Am., Vol. 54, pp. 1138-1142, 1973. 6. Chung, J . Y. and Blaser, D . A...Press, 1968. 14. Johnson, D . L., Koplik, J . and Dashen, R., "Theory of Dynamic Permeability and Tortuosity in <span class="hlt">Fluid-Saturated</span> <span class="hlt">Porous</span> Media", submitted</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4726633','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4726633"><span>Soret and Dufour Effects on MHD Peristaltic Flow of Jeffrey Fluid in a Rotating System with <span class="hlt">Porous</span> Medium</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hayat, Tasawar; Rafiq, Maimona; Ahmad, Bashir</p> <p>2016-01-01</p> <p>The objective of present paper is to examine the peristaltic flow of magnetohydrodynamic (MHD) Jeffrey <span class="hlt">fluid</span> <span class="hlt">saturating</span> <span class="hlt">porous</span> space in a channel through rotating frame. Unlike the previous attempts, the flow formulation is based upon modified Darcy's law <span class="hlt">porous</span> medium effect in Jeffrey fluid situation. In addition the impacts due to Soret and Dufour effects in the radiative peristaltic flow are accounted. Rosseland’s approximation has been utilized for the thermal radiative heat flux. Lubrication approach is implemented for the simplification. Resulting problems are solved for the stream function, temperature and concentration. Graphical results are prepared and analyzed for different parameters of interest entering into the problems. PMID:26808387</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26808387','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26808387"><span>Soret and Dufour Effects on MHD Peristaltic Flow of Jeffrey Fluid in a Rotating System with <span class="hlt">Porous</span> Medium.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hayat, Tasawar; Rafiq, Maimona; Ahmad, Bashir</p> <p>2016-01-01</p> <p>The objective of present paper is to examine the peristaltic flow of magnetohydrodynamic (MHD) Jeffrey <span class="hlt">fluid</span> <span class="hlt">saturating</span> <span class="hlt">porous</span> space in a channel through rotating frame. Unlike the previous attempts, the flow formulation is based upon modified Darcy's law <span class="hlt">porous</span> medium effect in Jeffrey fluid situation. In addition the impacts due to Soret and Dufour effects in the radiative peristaltic flow are accounted. Rosseland's approximation has been utilized for the thermal radiative heat flux. Lubrication approach is implemented for the simplification. Resulting problems are solved for the stream function, temperature and concentration. Graphical results are prepared and analyzed for different parameters of interest entering into the problems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JMMM..421..152S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JMMM..421..152S"><span>Magnetohydrodynamic stability of natural convection in a vertical <span class="hlt">porous</span> slab</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shankar, B. M.; Kumar, Jai; Shivakumara, I. S.</p> <p>2017-01-01</p> <p>The stability of the conduction regime of natural convection in an electrically conducting <span class="hlt">fluid</span> <span class="hlt">saturated</span> <span class="hlt">porous</span> vertical slab is investigated in the presence of a uniform external transverse magnetic field. The flow in the <span class="hlt">porous</span> medium is described by modified Brinkman-extended Darcy equation with fluid viscosity different from effective viscosity. The boundaries of the vertical <span class="hlt">porous</span> slab are assumed to be rigid-isothermal and electrically non-conducting. The resulting stability equations are solved numerically using Galerkin method. The critical Grashof number Gc, the critical wave number αc and the critical wave speed cc are computed for a wide range of <span class="hlt">porous</span> parameter σp, the ratio of effective viscosity to the fluid viscosity Λ, the Prandtl number Pr and the Hartmann number M. Based on these parameters, the stability characteristics of the system are discussed in detail. The presence of advective inertia is to instill instability on the flow in a <span class="hlt">porous</span> medium and found that the magnetic field, <span class="hlt">porous</span> parameter and ratio of viscosities have a stabilizing effect on both stationary and oscillatory wave instabilities. Besides, the value of Pr at which transition occurs from stationary to oscillatory mode of instability decreases with increasing M ,σp and Λ .</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002GeoJI.151..597B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002GeoJI.151..597B"><span>A differential scheme for elastic properties of <span class="hlt">rocks</span> with dry or saturated cracks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Berryman, James G.; Pride, Steven R.; Wang, Herbert F.</p> <p>2002-11-01</p> <p>Differential effective medium (DEM) theory is applied to the problem of estimating the physical properties of elastic media with penny-shaped cracks, filled either with gas or liquid. These cracks are assumed to be randomly oriented. It is known that such a model captures many of the essential physical features of <span class="hlt">fluid-saturated</span> or partially saturated <span class="hlt">rocks</span>. By making an assumption that the changes in certain factors depending only on Poisson's ratio do not strongly affect the results, it is possible to decouple the equations for bulk (K) and shear (G) modulus, and then integrate them analytically. The validity of this assumption is then tested by integrating the full DEM equations numerically. The analytical and numerical curves for both K and G are in very good agreement over the whole porosity range. Justification of the Poisson ratio approximation is also provided directly by the theory, which shows that as porosity tends to unity, Poisson's ratio tends towards small positive values for dry, cracked <span class="hlt">porous</span> media and tends to one-half for liquid-saturated samples. A rigorous stable fixed-point is obtained for Poisson's ratio, νc, of dry <span class="hlt">porous</span> media, where the location of this fixed-point depends only on the shape of the voids being added. Fixed-points occur at for spheres and νc~=πα/18 for cracks, where α is the aspect ratio of penny-shaped cracks. These theoretical results for the elastic constants are then compared and contrasted with results predicted by Gassmann's equations and with results of Mavko and Jizba, for both granite-like and sandstone-like examples. Gassmann's equations do not predict the observed liquid dependence of the shear modulus G at all. Mavko and Jizba predict the observed dependence of the shear modulus on the liquid bulk modulus for a small crack porosity and a very small aspect ratio, but fail to predict the observed behaviour at higher porosities. In contrast, the analytical approximations derived here give very satisfactory</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70029503','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70029503"><span>A <span class="hlt">porous</span> silica <span class="hlt">rock</span> ("tripoli") in the footwall of the Jurassic Úrkút manganese deposit, Hungary: composition, and origin through carbonate dissolution</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Polgari, Marta; Szabo, Zoltan; Szabo-Drubina, Magda; Hein, James R.; Yeh, Hsueh-Wen</p> <p>2005-01-01</p> <p>The mineralogical, chemical, and isotopic compositions were determined for a white tripoli from the footwall of the Jurassic Úrkút Mn-oxide ore deposit in the Bakony Mountains, Hungary. The tripoli consists of quartz and chalcedony, with SiO2 contents up to 100 wt.%; consequently, trace-element contents are very low. Oxygen isotopes and quartz crystallinity indicate a low-temperature diagenetic origin for this deposit. The tripoli was formed by dissolution of the carbonate portion of the siliceous (sponge spicules) Isztimér Limestone. Dissolution of the carbonate was promoted by inorganic and organic acids generated during diagensis and left a framework composed of diagenetic silica that preserved the original volume of the limestone layer. The relative enrichment of silica and high porosity is the result of that carbonate dissolution. The silty texture of this highly friable <span class="hlt">rock</span> is due to the structurally weak silica framework.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EPJAP..7834807M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EPJAP..7834807M"><span>Active chimney effect using heated <span class="hlt">porous</span> layers: optimum heat transfer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mehiris, Abdelhak; Ameziani, Djamel-Edine; Rahli, Omar; Bouhadef, Khadija; Bennacer, Rachid</p> <p>2017-05-01</p> <p>The purpose of the present work is to treat numerically the problem of the steady mixed convection that occurs in a vertical cylinder, opened at both ends and filled with a succession of three <span class="hlt">fluid</span> <span class="hlt">saturated</span> <span class="hlt">porous</span> elements, namely a partially <span class="hlt">porous</span> duct. The flow conditions fit with the classical Darcy-Brinkman model allowing analysing the flow structure on the overall domain. The induced heat transfer, in terms of local and average Nusselt numbers, is discussed for various controlling parameters as the <span class="hlt">porous</span> medium permeability, Rayleigh and Reynolds numbers. The efficiency of the considered system is improved by the injection/suction on the <span class="hlt">porous</span> matrices frontier. The undertaken numerical exploration particularly highlighted two possible types of flows, with and without fluid recirculation, which principally depend on the mixed convection regime. Thus, it is especially shown that recirculation zones appear in some domain areas under specific conditions, obvious by a negative central velocity and a prevalence of the natural convection effects, i.e., turnoff flow swirls. These latter are more accentuated in the areas close to the <span class="hlt">porous</span> obstacles and for weak permeability. Furthermore, when fluid injection or suction is considered, the heat transfer increases under suction and reduces under injection. Contribution to the topical issue "Materials for Energy Harvesting, Conversion and Storage II (ICOME 2016)", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.H21A1347Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.H21A1347Q"><span>Study on Two-Phase Flow in Heterogeneous <span class="hlt">Porous</span> Media by Light Transmission Method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qiao, W.</p> <p>2015-12-01</p> <p>The non-aqueous phase liquid (NAPL) released to the subsurface can form residual ganglia and globules occupying pores and also accumulate and form pools, in which multiphase system forms. Determining transient <span class="hlt">fluid</span> <span class="hlt">saturations</span> in a multiphase system is essential to understand the flow characteristics of systems and to perform effective remediation strategies. As a non-destructive and non-invasive laboratory technique utilized for the measurement of liquid saturation in <span class="hlt">porous</span> media, light transmission is of the lowest cost and safe. Utilization of Coupled Charge Device camera in light transmission systems provides a nearly instantaneous high-density array of spatial measurements over a very large dynamic range. The migration of NAPL and air spariging technique applied to remove NAPL in aquifer systems are typically two-phase flow problem. Because of the natural aquifer normally being heterogeneous, two 2-D sandboxes (Length55cm×width1.3cm×hight45cm) are set up to study the migration of gas and DNAPL in heterogeneous <span class="hlt">porous</span> media based on light transmission method and its application in two-phase flow. Model D for water/gas system developed by Niemet and Selker (2001) and Model NW-A for water/NAPL system developed by Zhang et al. (2014) are applied for the calculation of <span class="hlt">fluid</span> <span class="hlt">saturation</span> in the two experiments, respectively. The gas injection experiments show that the gas moves upward in the irregular channels, piling up beneath the low permeability lenses and starting lateral movement. Bypassing the lenses, the gas moves upward and forms continuous distribution in the top of the sandbox. The faster of gas injects, the wider of gas migration will be. The DNAPL infiltration experiment shows that TCE mainly moves downward as the influence of gravity, stopping vertical infiltration when reaching the low permeability lenses because of its failure to overcome the capillary pressure. Then, TCE accumulates on the surface and starts transverse movement. Bypassing the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5414904','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5414904"><span>Numerical solutions for steady thermal convection from a concentrated source in a <span class="hlt">porous</span> medium</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hickox, C.E.; Watts, H.A.</p> <p>1980-06-01</p> <p>Solutions for the steady, axisymmetric velocity and temperature fields associated with a point source of thermal energy in a <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> medium are obtained numerically through use of similarity transformations. The two cases considered are those of a point source located on the lower, insulated boundary of a semi-infinite region and a point source embedded in an infinite region. Numerical results are presented from which complete descriptions of the velocity and temperature fields can be constructed for Rayleigh numbers ranging from 10/sup -3/ to 10/sup 2/.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004ChPhL..21.1298X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004ChPhL..21.1298X"><span>Lattice Boltzmann Method for Diffusion-Reaction-Transport Processes in Heterogeneous <span class="hlt">Porous</span> Media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, You-Sheng; Zhong, Yi-Jun; Huang, Guo-Xiang</p> <p>2004-07-01</p> <p>Based on the lattice Boltzmann method and general theory of fluids flowing in <span class="hlt">porous</span> media, a numerical model is presented for the diffusion-reaction-transport (DRT) processes in <span class="hlt">porous</span> media. As a test, we simulate a DRT process in a two-dimensional horizontal heterogeneous <span class="hlt">porous</span> medium. The influence of gravitation in this case can be neglected, and the DRT process can be described by a strongly heterogeneous diagnostic test strip or a thin confined piece of soil with stochastically distributing property in horizontal directions. The results obtained for the relations between reduced <span class="hlt">fluid</span> <span class="hlt">saturation</span> S, concentration c1, and concentration c2 are shown by using the visualization computing technique. The computational efficiency and stability of the model are satisfactory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MS%26E..149a2214A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MS%26E..149a2214A"><span>Mixed Convection Opposing Flow in a Vertical <span class="hlt">Porous</span> Annulus-Two Temperature Model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Al-Rashed, Abdullah A. AA; J, Salman Ahmed N.; Khaleed, H. M. T.; Yunus Khan, T. M.; NazimAhamed, K. S.</p> <p>2016-09-01</p> <p>The opposing flow in a <span class="hlt">porous</span> medium refers to a condition when the forcing velocity flows in opposite direction to thermal buoyancy obstructing the buoyant force. The present research refers to the effect of opposing flow in a vertical <span class="hlt">porous</span> annulus embedded with <span class="hlt">fluid</span> <span class="hlt">saturated</span> <span class="hlt">porous</span> medium. The thermal non-equilibrium approach with Darcy modal is considered. The boundary conditions are such that the inner radius is heated with constant temperature Tw the outer radius is maintained at constant temperature Tc. The coupled nonlinear partial differential equations such as momentum equation, energy equation for fluid and energy equation for solid are solved using the finite element method. The opposing flow variation of average Nusselt number with respect to radius ratio Rr, Aspect ratioAr and Radiation parameter Rd for different values of Peclet number Pe are investigated. It is found that the flow behavior is quite different from that of aiding flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70010089','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70010089"><span>High-pressure mechanical instability in <span class="hlt">rocks</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Byerlee, J.D.; Brace, W.F.</p> <p>1969-01-01</p> <p>At a confining pressure of a few kilobars, deformation of many sedimentary <span class="hlt">rocks</span>, altered mafic <span class="hlt">rocks</span>, <span class="hlt">porous</span> volcanic <span class="hlt">rocks</span>, and sand is ductile, in that instabilities leading to audible elastic shocks are absent. At pressures of 7 to 10 kilobars, however, unstable faulting and stick-slip in certain of these <span class="hlt">rocks</span> was observed. This high pressure-low temperature instability might be responsible for earthquakes in deeply buried sedimentary or volcanic sequences.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016HydJ...24.1359J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016HydJ...24.1359J"><span>Groundwater flow dynamics of weathered hard-<span class="hlt">rock</span> aquifers under climate-change conditions: an illustrative example of numerical modeling through the equivalent <span class="hlt">porous</span> media approach in the north-western Pyrenees (France)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jaunat, J.; Dupuy, A.; Huneau, F.; Celle-Jeanton, H.; Le Coustumer, P.</p> <p>2016-09-01</p> <p>A numerical groundwater model of the weathered crystalline aquifer of Ursuya (a major water source for the north-western Pyrenees region, south-western France) has been computed based on monitoring of hydrological, hydrodynamic and meteorological parameters over 3 years. The equivalent <span class="hlt">porous</span> media model was used to simulate groundwater flow in the different layers of the weathered profile: from surface to depth, the weathered layer (5 · 10-8 ≤ K ≤ 5 · 10-7 m s-1), the transition layer (7 · 10-8 ≤ K ≤ 1 · 10-5 m s-1, the highest values being along major discontinuities), two fissured layers (3.5 · 10-8 ≤ K ≤ 5 · 10-4 m s-1, depending on weathering profile conditions and on the existence of active fractures), and the hard-<span class="hlt">rock</span> basement simulated with a negligible hydraulic conductivity ( K = 1 10 -9 ). Hydrodynamic properties of these five calculation layers demonstrate both the impact of the weathering degree and of the discontinuities on the groundwater flow. The great agreement between simulated and observed hydraulic conditions allowed for validation of the methodology and its proposed use for application on analogous aquifers. With the aim of long-term management of this strategic aquifer, the model was then used to evaluate the impact of climate change on the groundwater resource. The simulations performed according to the most pessimistic climatic scenario until 2050 show a low sensitivity of the aquifer. The decreasing trend of the natural discharge is estimated at about -360 m3 y-1 for recharge decreasing at about -5.6 mm y-1 (0.8 % of annual recharge).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoJI.204.1531B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoJI.204.1531B"><span>Shear wave splitting of the 2009 L'Aquila seismic sequence: <span class="hlt">fluid</span> <span class="hlt">saturated</span> microcracks and crustal fractures in the Abruzzi region (Central Apennines, Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baccheschi, P.; Pastori, M.; Margheriti, L.; Piccinini, D.</p> <p>2016-03-01</p> <p>The Abruzzi region is located in the Central Apennines Neogene fold-and-thrust belt and has one of the highest seismogenic potential in Italy, with high and diffuse crustal seismicity related to NE-SW oriented extension. In this study, we investigate the detailed spatial variation in shear wave splitting providing high-resolution anisotropic structure beneath the L'Aquila region. To accomplish this, we performed a systematic analysis of crustal anisotropic parameters: fast polarization direction (ϕ) and delay time (δt). We benefit from the dense coverage of seismic stations operating in the area and from a catalogue of several accurate earthquake locations of the 2009 L'Aquila seismic sequence, related to the Mw 6.1 2009 L'Aquila main shock, to describe in detail the geometry of the anisotropic volume around the active faults that ruptured. The spatial variations both in ϕ and δt suggest a complex anisotropic structure beneath the region caused by a combination of both structural- and stress-induced mechanisms. The average ϕ is NNW-SSE oriented (N141°), showing clear similarity both with the local fault strike and the SHmax. In the central part of the study area fast axes are oriented NW-SE, while moving towards the northeastern and northwestern sectors the fast directions clearly diverge from the general trend of NW-SE and rotate accordingly to the local fault strikes. The above-mentioned fault-parallel ϕ distribution suggests that the observed anisotropy is mostly controlled by the local fault-related structure. Toward the southeast fast directions become orthogonal both to strike of the local mapped faults and to the SHmax. Here, ϕ are predominantly oriented NE-SW; we interpret this orientation as due to the presence of a highly fractured and overpressurized <span class="hlt">rock</span> volume which should be responsible of the 90° flips in ϕ and the increase in δt. Another possible mechanism for NE-SW orientation of ϕ in the southeastern sector could be ascribed to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4682809','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4682809"><span>Hydromagnetic Flow and Heat Transfer over a <span class="hlt">Porous</span> Oscillating Stretching Surface in a Viscoelastic Fluid with <span class="hlt">Porous</span> Medium</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Khan, Sami Ullah; Ali, Nasir; Abbas, Zaheer</p> <p>2015-01-01</p> <p>An analysis is carried out to study the heat transfer in unsteady two-dimensional boundary layer flow of a magnetohydrodynamics (MHD) second grade fluid over a <span class="hlt">porous</span> oscillating stretching surface embedded in <span class="hlt">porous</span> medium. The flow is induced due to infinite elastic sheet which is stretched periodically. With the help of dimensionless variables, the governing flow equations are reduced to a system of non-linear partial differential equations. This system has been solved numerically using the finite difference scheme, in which a coordinate transformation is used to transform the semi-infinite physical space to a bounded computational domain. The influence of the involved parameters on the flow, the temperature distribution, the skin-friction coefficient and the local Nusselt number is shown and discussed in detail. The study reveals that an oscillatory sheet embedded in a <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> medium generates oscillatory motion in the fluid. The amplitude and phase of oscillations depends on the rheology of the fluid as well as on the other parameters coming through imposed boundary conditions, inclusion of body force term and permeability of the <span class="hlt">porous</span> medium. It is found that amplitude of flow velocity increases with increasing viscoelastic and mass suction/injection parameters. However, it decreases with increasing the strength of the applied magnetic field. Moreover, the temperature of fluid is a decreasing function of viscoelastic parameter, mass suction/injection parameter and Prandtl number. PMID:26657931</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26657931','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26657931"><span>Hydromagnetic Flow and Heat Transfer over a <span class="hlt">Porous</span> Oscillating Stretching Surface in a Viscoelastic Fluid with <span class="hlt">Porous</span> Medium.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Khan, Sami Ullah; Ali, Nasir; Abbas, Zaheer</p> <p>2015-01-01</p> <p>An analysis is carried out to study the heat transfer in unsteady two-dimensional boundary layer flow of a magnetohydrodynamics (MHD) second grade fluid over a <span class="hlt">porous</span> oscillating stretching surface embedded in <span class="hlt">porous</span> medium. The flow is induced due to infinite elastic sheet which is stretched periodically. With the help of dimensionless variables, the governing flow equations are reduced to a system of non-linear partial differential equations. This system has been solved numerically using the finite difference scheme, in which a coordinate transformation is used to transform the semi-infinite physical space to a bounded computational domain. The influence of the involved parameters on the flow, the temperature distribution, the skin-friction coefficient and the local Nusselt number is shown and discussed in detail. The study reveals that an oscillatory sheet embedded in a <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> medium generates oscillatory motion in the fluid. The amplitude and phase of oscillations depends on the rheology of the fluid as well as on the other parameters coming through imposed boundary conditions, inclusion of body force term and permeability of the <span class="hlt">porous</span> medium. It is found that amplitude of flow velocity increases with increasing viscoelastic and mass suction/injection parameters. However, it decreases with increasing the strength of the applied magnetic field. Moreover, the temperature of fluid is a decreasing function of viscoelastic parameter, mass suction/injection parameter and Prandtl number.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFMNG23E0121P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFMNG23E0121P"><span>Nonlinear Behavior Of Saturated <span class="hlt">Porous</span> Media Under External Impact</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Perepechko, Y.</p> <p>2005-12-01</p> <p>This paper deals with nonlinear behavior of liquid saturated <span class="hlt">porous</span> media in gravity filed under external impact. The continuum is assumed to be a two-velocity medium; it consists of a deformable <span class="hlt">porous</span> matrix (with Maxwell's reology) and a Newtonian liquid that saturates this matrix. The energy dissipation in this model takes place due the interface friction between the solid matrix and saturating liquid, and also through relaxation of inelastic shear stress in the <span class="hlt">porous</span> matrix. The elaborated nonisothermal mathematical model for this kind of medium is a thermodynamically consistent and closed model. Godunov's explicit difference scheme was used for computer simulation; the method implies numerical simulation for discontinuity decay in flux calculations. As an illustrative example, we consider the formation of dissipation structures in a plain layer of that medium after pulse or periodic impact on the background of liquid filtration through the <span class="hlt">porous</span> matrix. At the process beginning, one can observe elastic behavior of the <span class="hlt">porous</span> matrix. Deformation spreading through the saturated <span class="hlt">porous</span> matrix occurs almost without distortions and produces a channel-shaped zone of stretching with a high porosity. Later on, dissipation processes and reology properties of <span class="hlt">porous</span> medium causes the diffusion of this channel. We also observe a correlation between the liquid distribution (porosity for the solid matrix) and dilatancy fields; this allows us to restore the dilatancy field from the measured <span class="hlt">fluid</span> <span class="hlt">saturation</span> of the medium. This work was supported by the RFBR (Grant No. 04-05-64107), the Presidium of SB RAS (Grant 106), the President's Grants (NSh-2118.2003.5, NSh-1573.2003.5).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=Igneous+AND+rocks&id=EJ362861','ERIC'); return false;" href="https://eric.ed.gov/?q=Igneous+AND+rocks&id=EJ362861"><span>Talking <span class="hlt">Rocks</span>.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Rice, Dale; Corley, Brenda</p> <p>1987-01-01</p> <p>Discusses some of the ways that <span class="hlt">rocks</span> can be used to enhance children's creativity and their interest in science. Suggests the creation of a dramatic production involving <span class="hlt">rocks</span>. Includes basic information on sedimentary, igneous, and metamorphic <span class="hlt">rocks</span>. (TW)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=Sedimentary+AND+rocks&pg=2&id=EJ362861','ERIC'); return false;" href="http://eric.ed.gov/?q=Sedimentary+AND+rocks&pg=2&id=EJ362861"><span>Talking <span class="hlt">Rocks</span>.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Rice, Dale; Corley, Brenda</p> <p>1987-01-01</p> <p>Discusses some of the ways that <span class="hlt">rocks</span> can be used to enhance children's creativity and their interest in science. Suggests the creation of a dramatic production involving <span class="hlt">rocks</span>. Includes basic information on sedimentary, igneous, and metamorphic <span class="hlt">rocks</span>. (TW)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5341564','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5341564"><span>Dispersivity as an oil reservoir <span class="hlt">rock</span> characteristic</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Menzie, D.E.; Dutta, S.</p> <p>1989-12-01</p> <p>The main objective of this research project is to establish dispersivity, {alpha}{sub d}, as an oil reservoir <span class="hlt">rock</span> characteristic and to use this reservoir <span class="hlt">rock</span> property to enhance crude oil recovery. A second objective is to compare the dispersion coefficient and the dispersivity of various reservoir <span class="hlt">rocks</span> with other <span class="hlt">rock</span> characteristics such as: porosity, permeability, capillary pressure, and relative permeability. The dispersivity of a <span class="hlt">rock</span> was identified by measuring the physical mixing of two miscible fluids, one displacing the other in a <span class="hlt">porous</span> medium. 119 refs., 27 figs., 12 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16089868','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16089868"><span>Natural convection in tilted cylindrical cavities embedded in <span class="hlt">rocks</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sánchez, F; Higuera, F J; Medina, A</p> <p>2005-06-01</p> <p>This paper presents a theoretical investigation of the low Rayleigh number conjugate natural convection in a slender tilted cylindrical cavity which is embedded in a solid that is subject to a uniform vertical temperature gradient. Two cases have been analyzed; a fluid-filled cavity and a cavity filled with a <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> medium. The temperature of the solid and the velocity, temperature, and pressure in the cavity have been determined by analytically solving the coupled problems within and around the cavity. The effect of the ratio of the thermal conductivity of the material in the cavity to the thermal conductivity of the solid on the structure of the convection flow is discussed. The theoretical results for convection in the fluid-filled cavity are shown to be in good agreement with experimental PIV measurements.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/883756','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/883756"><span>Seismoelectric Phenomena in <span class="hlt">Fluid-Saturated</span> Sediments</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Block, G I; Harris, J G</p> <p>2005-04-22</p> <p>Seismoelectric phenomena in sediments arise from acoustic wave-induced fluid motion in the pore space, which perturbs the electrostatic equilibrium of the electric double layer on the grain surfaces. Experimental techniques and the apparatus built to study this electrokinetic (EK) effect are described and outcomes for studies of seismoelectric phenomena in loose glass microspheres and medium-grain sand are presented. By varying the NaCl concentration in the pore fluid, we measured the conductivity dependence of two kinds of EK behavior: (1) the electric fields generated within the samples by the passage of transmitted acoustic waves, and (2) the electromagnetic wave produced at the fluid-sediment interface by the incident acoustic wave. Both phenomena are caused by relative fluid motion in the sediment pores--this feature is characteristic of poroelastic (Biot) media, but not predicted by either viscoelastic fluid or solid models. A model of plane-wave reflection from a fluid-sediment interface using EK-Biot theory leads to theoretical predictions that compare well to the experimental data for both sand and glass microspheres.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/825768','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/825768"><span>Underground Research Laboratories for Crystalline <span class="hlt">Rock</span> and Sedimentary <span class="hlt">Rock</span> in Japan</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shigeta, N.; Takeda, S.; Matsui, H.; Yamasaki, S.</p> <p>2003-02-27</p> <p>The Japan Nuclear Cycle Development Institute (JNC) has started two off-site (generic) underground research laboratory (URL) projects, one for crystalline <span class="hlt">rock</span> as a fractured media and the other for sedimentary <span class="hlt">rock</span> as a <span class="hlt">porous</span> media. This paper introduces an overview and current status of these projects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA00987.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA00987.html"><span>"<span class="hlt">Rock</span> Garden"</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>1997-10-14</p> <p>This false color composite image of the <span class="hlt">Rock</span> Garden shows the <span class="hlt">rocks</span> "Shark" and "Half Dome" at upper left and middle, respectively. Between these two large <span class="hlt">rocks</span> is a smaller <span class="hlt">rock</span> (about 0.20 m wide, 0.10 m high, and 6.33 m from the Lander) that was observed close-up with the Sojourner rover (see PIA00989). http://photojournal.jpl.nasa.gov/catalog/PIA00987</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=Rock+AND+Cycle&id=EJ878131','ERIC'); return false;" href="https://eric.ed.gov/?q=Rock+AND+Cycle&id=EJ878131"><span>Science <span class="hlt">Rocks</span>!</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Prestwich, Dorothy; Sumrall, Joseph; Chessin, Debby A.</p> <p>2010-01-01</p> <p>It all began one Monday morning. Raymond could not wait to come to large group. In his hand, he held a chunk of white granite he had found. "Look at my beautiful <span class="hlt">rock</span>!" he cried. The <span class="hlt">rock</span> was passed around and examined by each student. "I wonder how <span class="hlt">rocks</span> are made?" wondered one student. "Where do they come from?"…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=rock&pg=4&id=EJ758292','ERIC'); return false;" href="http://eric.ed.gov/?q=rock&pg=4&id=EJ758292"><span><span class="hlt">Rock</span> Finding</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Rommel-Esham, Katie; Constable, Susan D.</p> <p>2006-01-01</p> <p>In this article, the authors discuss a literature-based activity that helps students discover the importance of making detailed observations. In an inspiring children's classic book, "Everybody Needs a <span class="hlt">Rock</span>" by Byrd Baylor (1974), the author invites readers to go "<span class="hlt">rock</span> finding," laying out 10 rules for finding a "perfect" <span class="hlt">rock</span>. In this way, the…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=rock&pg=6&id=EJ699826','ERIC'); return false;" href="http://eric.ed.gov/?q=rock&pg=6&id=EJ699826"><span><span class="hlt">Rock</span> Art</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Henn, Cynthia A.</p> <p>2004-01-01</p> <p>There are many interpretations for the symbols that are seen in <span class="hlt">rock</span> art, but no decoding key has ever been discovered. This article describes one classroom's experiences with a lesson on <span class="hlt">rock</span> art--making their <span class="hlt">rock</span> art and developing their own personal symbols. This lesson allowed for creativity, while giving an opportunity for integration…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://files.eric.ed.gov/fulltext/ED241330.pdf','ERIC'); return false;" href="http://files.eric.ed.gov/fulltext/ED241330.pdf"><span>Collecting <span class="hlt">Rocks</span>.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Barker, Rachel M.</p> <p></p> <p>One of a series of general interest publications on science topics, the booklet provides those interested in <span class="hlt">rock</span> collecting with a nontechnical introduction to the subject. Following a section examining the nature and formation of igneous, sedimentary, and metamorphic <span class="hlt">rocks</span>, the booklet gives suggestions for starting a <span class="hlt">rock</span> collection and using…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=Rock+AND+Cycle&id=EJ878131','ERIC'); return false;" href="http://eric.ed.gov/?q=Rock+AND+Cycle&id=EJ878131"><span>Science <span class="hlt">Rocks</span>!</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Prestwich, Dorothy; Sumrall, Joseph; Chessin, Debby A.</p> <p>2010-01-01</p> <p>It all began one Monday morning. Raymond could not wait to come to large group. In his hand, he held a chunk of white granite he had found. "Look at my beautiful <span class="hlt">rock</span>!" he cried. The <span class="hlt">rock</span> was passed around and examined by each student. "I wonder how <span class="hlt">rocks</span> are made?" wondered one student. "Where do they come from?"…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=rocks&pg=7&id=EJ699826','ERIC'); return false;" href="https://eric.ed.gov/?q=rocks&pg=7&id=EJ699826"><span><span class="hlt">Rock</span> Art</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Henn, Cynthia A.</p> <p>2004-01-01</p> <p>There are many interpretations for the symbols that are seen in <span class="hlt">rock</span> art, but no decoding key has ever been discovered. This article describes one classroom's experiences with a lesson on <span class="hlt">rock</span> art--making their <span class="hlt">rock</span> art and developing their own personal symbols. This lesson allowed for creativity, while giving an opportunity for integration…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=rocks&pg=5&id=EJ758292','ERIC'); return false;" href="https://eric.ed.gov/?q=rocks&pg=5&id=EJ758292"><span><span class="hlt">Rock</span> Finding</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Rommel-Esham, Katie; Constable, Susan D.</p> <p>2006-01-01</p> <p>In this article, the authors discuss a literature-based activity that helps students discover the importance of making detailed observations. In an inspiring children's classic book, "Everybody Needs a <span class="hlt">Rock</span>" by Byrd Baylor (1974), the author invites readers to go "<span class="hlt">rock</span> finding," laying out 10 rules for finding a "perfect" <span class="hlt">rock</span>. In this way, the…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1411375P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1411375P"><span>Capillary heterogeneity in sandstones <span class="hlt">rocks</span> during CO2/water core-flooding experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pini, R.; Krevor, S. C. M.; Krause, M. H.; Benson, S. M.</p> <p>2012-04-01</p> <p>. Additionally, during a core-flooding experiment, X-ray Computed Tomography (CT) scanning allows for precise imaging of <span class="hlt">fluid</span> <span class="hlt">saturations</span> at a resolution of about 1mm3. It is shown that a distribution of capillary pressure curves can be associated to the observed distribution of CO2 saturation within the core, allowing for the quantification of capillary heterogeneity at the sub-core scale. This set of data is further exploited to investigate scaling laws that are based on the concept of similar media and that are used to describe the spatial variation of <span class="hlt">rock</span> hydraulic properties. In particular, a set of scaling factors is obtained that relates the capillary pressure curve in each voxel to a representative mean, thus simplifying considerably the statistical description of capillary heterogeneity. Additionally, this proves the suitability of scaling laws such as the Leverett J Function to be applied at the sub-core scale, thus allowing the derivation of sub-core scale permeability distributions by combination with independent measurement of the corresponding porosity distribution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/7151716','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7151716"><span><span class="hlt">Porous</span> media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bullien, F.A.L. . Dept. of Chemical Engineering)</p> <p>1992-01-01</p> <p>The unique property of a <span class="hlt">porous</span> medium, the one that distinguishes it from other solid bodies on the one hand and from simple conduits on the other, is its complicated pore structure. Fluid flow, diffusion, and electrical conduction in <span class="hlt">porous</span> media take place within extremely complicated microscopic boundaries that in the past made a rigorous solution of the equations of change in the capillary network practically impossible. The past state of affairs is one of the reasons why some of the brilliant and successful practitioners in the field of flow through <span class="hlt">porous</span> media have tried, as much as possible, to stick with the continuum approach in which no attention is paid to pores or pore structure. Another reason is that the continuum approach is often adequate for the phenomenological description of macroscopic transport processes in <span class="hlt">porous</span> media. This book has been written with the primary purpose of presenting in an organized manner the most pertinent information available on the role of pore structure and then putting it to use in the interpretation of experimental data and the results of model calculations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1005634','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1005634"><span>Measurement and Estimation of Organic-Liquid/Water Interfacial Areas for Several Natural <span class="hlt">Porous</span> Media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Brusseau, M.L.; Narter, M.; Schnaar, G.; Marble, J.</p> <p>2009-06-01</p> <p>The objective of this study was to quantitatively characterize the impact of <span class="hlt">porous</span>-medium texture on interfacial area between immiscible organic liquid and water residing within natural <span class="hlt">porous</span> media. Synchrotron X-ray microtomography was used to obtain high-resolution, three-dimensional images of solid and liquid phases in packed columns. The image data were processed to generate quantitative measurements of organic-liquid/water interfacial area and of organic-liquid blob sizes. Ten <span class="hlt">porous</span> media, comprising a range of median grain sizes, grain-size distributions, and geochemical properties, were used to evaluate the impact of <span class="hlt">porous</span>-medium texture on interfacial area. The results show that fluid-normalized specific interfacial area (A{sub f}) and maximum specific interfacial area (A{sub m}) correlate very well to inverse median grain diameter. These functionalities were shown to result from a linear relationship between effective organic-liquid blob diameter and median grain diameter. These results provide the basis for a simple method for estimating specific organic-liquid/water interfacial area as a function of <span class="hlt">fluid</span> <span class="hlt">saturation</span> for a given <span class="hlt">porous</span> medium. The availability of a method for which the only parameter needed is the simple-to-measure median grain diameter should be of great utility for a variety of applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA06918&hterms=arisen&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Darisen','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA06918&hterms=arisen&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Darisen"><span>'Escher' <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/> [figure removed for brevity, see original site] Chemical Changes in 'Endurance' <span class="hlt">Rocks</span> <p/> [figure removed for brevity, see original site] Figure 1 <p/> This false-color image taken by NASA's Mars Exploration Rover Opportunity shows a <span class="hlt">rock</span> dubbed 'Escher' on the southwestern slopes of 'Endurance Crater.' Scientists believe the <span class="hlt">rock</span>'s fractures, which divide the surface into polygons, may have been formed by one of several processes. They may have been caused by the impact that created Endurance Crater, or they might have arisen when water leftover from the <span class="hlt">rock</span>'s formation dried up. A third possibility is that much later, after the <span class="hlt">rock</span> was formed, and after the crater was created, the <span class="hlt">rock</span> became wet once again, then dried up and developed cracks. Opportunity has spent the last 14 sols investigating Escher, specifically the target dubbed 'Kirchner,' and other similar <span class="hlt">rocks</span> with its scientific instruments. This image was taken on sol 208 (Aug. 24, 2004) by the rover's panoramic camera, using the 750-, 530- and 430-nanometer filters. <p/> The graph above shows that <span class="hlt">rocks</span> located deeper into 'Endurance Crater' are chemically altered to a greater degree than <span class="hlt">rocks</span> located higher up. This chemical alteration is believed to result from exposure to water. <p/> Specifically, the graph compares ratios of chemicals between the deep <span class="hlt">rock</span> dubbed 'Escher,' and the more shallow <span class="hlt">rock</span> called 'Virginia,' before (red and blue lines) and after (green line) the Mars Exploration Rover Opportunity drilled into the <span class="hlt">rocks</span>. As the red and blue lines indicate, Escher's levels of chlorine relative to Virginia's went up, and sulfur down, before the rover dug a hole into the <span class="hlt">rocks</span>. This implies that the surface of Escher has been chemically altered to a greater extent than the surface of Virginia. Scientists are still investigating the role water played in influencing this trend. <p/> These data were taken by the rover's alpha particle X-ray spectrometer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA06918&hterms=Escher&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DEscher','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA06918&hterms=Escher&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DEscher"><span>'Escher' <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/> [figure removed for brevity, see original site] Chemical Changes in 'Endurance' <span class="hlt">Rocks</span> <p/> [figure removed for brevity, see original site] Figure 1 <p/> This false-color image taken by NASA's Mars Exploration Rover Opportunity shows a <span class="hlt">rock</span> dubbed 'Escher' on the southwestern slopes of 'Endurance Crater.' Scientists believe the <span class="hlt">rock</span>'s fractures, which divide the surface into polygons, may have been formed by one of several processes. They may have been caused by the impact that created Endurance Crater, or they might have arisen when water leftover from the <span class="hlt">rock</span>'s formation dried up. A third possibility is that much later, after the <span class="hlt">rock</span> was formed, and after the crater was created, the <span class="hlt">rock</span> became wet once again, then dried up and developed cracks. Opportunity has spent the last 14 sols investigating Escher, specifically the target dubbed 'Kirchner,' and other similar <span class="hlt">rocks</span> with its scientific instruments. This image was taken on sol 208 (Aug. 24, 2004) by the rover's panoramic camera, using the 750-, 530- and 430-nanometer filters. <p/> The graph above shows that <span class="hlt">rocks</span> located deeper into 'Endurance Crater' are chemically altered to a greater degree than <span class="hlt">rocks</span> located higher up. This chemical alteration is believed to result from exposure to water. <p/> Specifically, the graph compares ratios of chemicals between the deep <span class="hlt">rock</span> dubbed 'Escher,' and the more shallow <span class="hlt">rock</span> called 'Virginia,' before (red and blue lines) and after (green line) the Mars Exploration Rover Opportunity drilled into the <span class="hlt">rocks</span>. As the red and blue lines indicate, Escher's levels of chlorine relative to Virginia's went up, and sulfur down, before the rover dug a hole into the <span class="hlt">rocks</span>. This implies that the surface of Escher has been chemically altered to a greater extent than the surface of Virginia. Scientists are still investigating the role water played in influencing this trend. <p/> These data were taken by the rover's alpha particle X-ray spectrometer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMGC51A0921P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMGC51A0921P"><span>Use of Various <span class="hlt">Rock</span> Physics Models Combined with a <span class="hlt">Rock</span> Physics Database to Better Characterize Velocity Dispersion Effects in Potential Enhanced Oil Recovery, Carbon Sequestration and Hydrothermal Sites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Purcell, C. C.; Mur, A. J.; Delany, D.; Haljasmaa, I. V.; Soong, Y.; Harbert, W.</p> <p>2011-12-01</p> <p>The exploration of velocity differences in various <span class="hlt">fluid</span> <span class="hlt">saturated</span> <span class="hlt">rock</span> types under reservoir conditions should prove to be useful in seismic monitoring of sequestration and hydrothermal sites. Different saturation values, along with mixtures of other common pore fluids could help delineate various areas of a CO2 flood or enhanced geothermal pressurization, in addition to estimating a minimum saturation amount needed to be seen in seismic surveys. We also explore the effects of varying parameters on the saturated velocities, including porosity, bulk frame composition, pressure, temperature, different pore filling phases, fluid mixtures, and compliant porosity. A software toolkit is currently in development that would allow exploration of these parameters to be easily achieved and visualized. Fluid substitution using Gassmann's equation (Gassmann [1]) is an important tool in the analysis of velocity dispersion in saturated <span class="hlt">rocks</span>. Mavko and Jizba [2] created a model of squirt dispersion for elastic wave velocities at ultrasonic frequencies that predicts total dispersion for fluid filled <span class="hlt">rocks</span>. Gurevich et al. [3] extend the Mavko-Jizba expressions to low fluid bulk modulus situations, such as gas filled <span class="hlt">rocks</span>. These equations are typically used to calculate velocities of <span class="hlt">rocks</span> filled with typical pore filling phases such as brine or gas. Purcell et al. [4] compared these equations to CO2 saturated limestone samples at reservoir pressures and temperatures. This paper compares the accuracy of these equations over various pressures and temperature ranges for a variety of <span class="hlt">rock</span> types. Dry <span class="hlt">rock</span> ultrasonic lab measurements of velocity have been made for carbonate, sandstone, rhyolite and coal and incorporated into a <span class="hlt">rock</span> physics database. In addition, waveforms for each measurement have been used to estimate Q. Measurements were made between 2.3 and 50 MPa with generally a minimum of 40 measurements per sample completed. Various saturating phases, including supercritical CO</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA06919&hterms=Earhart+Amelia&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DEarhart%252C%2BAmelia','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA06919&hterms=Earhart+Amelia&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DEarhart%252C%2BAmelia"><span>'Earhart' <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/> This false-color image taken by NASA's Mars Exploration Rover Opportunity shows a <span class="hlt">rock</span> informally named 'Earhart' on the lower slopes of 'Endurance Crater.' The <span class="hlt">rock</span> was named after the pilot Amelia Earhart. Like 'Escher' and other <span class="hlt">rocks</span> dotting the bottom of Endurance, scientists believe fractures in Earhart could have been formed by one of several processes. They may have been caused by the impact that created Endurance Crater, or they might have arisen when water leftover from the <span class="hlt">rock</span>'s formation dried up. A third possibility is that much later, after the <span class="hlt">rock</span> was formed, and after the crater was created, the <span class="hlt">rock</span> became wet once again, then dried up and developed cracks. Rover team members do not have plans to investigate Earhart in detail because it is located across potentially hazardous sandy terrain. This image was taken on sol 219 (Sept. 4) by the rover's panoramic camera, using its 750-, 530- and 430-nanometer filters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014StGM...36...79O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014StGM...36...79O"><span><span class="hlt">Rock</span> Pore Structure as Main Reason of <span class="hlt">Rock</span> Deterioration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ondrášik, Martin; Kopecký, Miloslav</p> <p>2014-03-01</p> <p>Crashed or dimensional <span class="hlt">rocks</span> have been used as natural construction material, decoration stone or as material for artistic sculptures. Especially old historical towns not only in Slovakia have had experiences with use of stones for construction purposes for centuries. The whole buildings were made from dimensional stone, like sandstone, limestone or rhyolite. Pavements were made especially from basalt, andesite, rhyolite or granite. Also the most common modern construction material - concrete includes large amounts of crashed <span class="hlt">rock</span>, especially limestone, dolostone and andesite. However, <span class="hlt">rock</span> as any other material if exposed to exogenous processes starts to deteriorate. Especially mechanical weathering can be very intensive if <span class="hlt">rock</span> with unsuitable <span class="hlt">rock</span> properties is used. For long it had been believed that repeated freezing and thawing in relation to high absorption is the main reason of the <span class="hlt">rock</span> deterioration. In Slovakia for many years the high water absorption was set as exclusion criterion for use of <span class="hlt">rocks</span> and stones in building industry. Only after 1989 the absorption was accepted as merely informational <span class="hlt">rock</span> property and not exclusion. The reason of the change was not the understanding of the relationship between the porosity and <span class="hlt">rock</span> deterioration, but more or less good experiences with some high <span class="hlt">porous</span> <span class="hlt">rocks</span> used in constructions exposed to severe weather conditions and proving a lack of relationship between <span class="hlt">rock</span> freeze-thaw resistivity and water absorption. Results of the recent worldwide research suggest that understanding a resistivity of <span class="hlt">rocks</span> against deterioration is hidden not in the absorption but in the structure of <span class="hlt">rock</span> pores in relation to thermodynamic properties of pore water and tensile strength of <span class="hlt">rocks</span> and <span class="hlt">rock</span> minerals. Also this article presents some results of research on <span class="hlt">rock</span> deterioration and pore structure performed on 88 <span class="hlt">rock</span> samples. The results divide the <span class="hlt">rocks</span> tested into two groups - group N in which the pore water does not freeze</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994JAG....32..321L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994JAG....32..321L"><span>Prediction of thermal conductivity in reservoir <span class="hlt">rocks</span> using fabric theory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Luo, Ming; Wood, James R.; Cathles, Lawrence M.</p> <p>1994-12-01</p> <p>An accurate prediction of the thermal conductivity of reservoir <span class="hlt">rocks</span> in the subsurface is extremely important for a quantitative analysis of basin thermal history and hydrocarbon maturation. A model for calculating the thermal conductivity of reservoir <span class="hlt">rocks</span> as a function of mineral composition, porosity, fluid type, and temperature has been developed based on fabric theory and experimental data. The study indicates that thermal conductivities of reservoir <span class="hlt">rocks</span> are dependent on the volume fraction of components (minerals, porosity, and fluids), the temperature, and the fraction of series elements ( FSE) which represents the way that the mineral components aggregate. The sensitivity test of the fabric model shows that quartz is the most sensitive mineral for the thermal conductivity of clastic <span class="hlt">rocks</span>. The study results indicate that the FSE value is very critical. Different lithologies have different optimum FSE values because of different textures and sedimentary structures. The optimum FSE values are defined as those which result in the least error in the model computation of the thermal conductivity of the <span class="hlt">rocks</span>. These values are 0.444 for water-saturated clay <span class="hlt">rocks</span>, 0.498 for water-saturated sandstones, and 0.337 for water-saturated carbonates. Compared with the geometric mean model, the fabric model yields better results for the thermal conductivity, largely because the model parameters can be adjusted to satisfy different lithologies and to minimize the mean errors. The fabric model provides a good approach for estimating paleothermal conductivity in complex <span class="hlt">rock</span> systems based on the mineral composition and pore <span class="hlt">fluid</span> <span class="hlt">saturation</span> of the <span class="hlt">rocks</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870012895','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870012895"><span><span class="hlt">Rock</span> flows</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Matveyev, S. N.</p> <p>1986-01-01</p> <p><span class="hlt">Rock</span> flows are defined as forms of spontaneous mass movements, commonly found in mountainous countries, which have been studied very little. The article considers formations known as <span class="hlt">rock</span> rivers, <span class="hlt">rock</span> flows, boulder flows, boulder stria, gravel flows, <span class="hlt">rock</span> seas, and rubble seas. It describes their genesis as seen from their morphological characteristics and presents a classification of these forms. This classification is based on the difference in the genesis of the rubbly matter and characterizes these forms of mass movement according to their source, drainage, and deposit areas.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6018773','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6018773"><span>Natural convection flow and heat transfer between a fluid layer and a <span class="hlt">porous</span> layer inside a rectangular enclosure</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Beckermann, C.; Ramadhyani, S.; Viskanta, R. )</p> <p>1987-05-01</p> <p>A numerical and experimental study is performed to analyze the steady-state natural convection fluid flow and heat transfer in a vertical rectangular enclosure that is partially filled with a vertical layer of a <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> medium. The flow in the <span class="hlt">porous</span> layer is modeled utilizing the Brinkman-Forchheimer-extended Darcy equations. The numerical model is verified by conducting a number of experiments, with spherical glass beads as the <span class="hlt">porous</span> medium and water and glycerin as the fluids, in rectangular test cells. The agreement between the flow visualization results and temperature measurements and the numerical model is, in general, good. It is found that the amount of fluid penetrating from the fluid region into the <span class="hlt">porous</span> layer depends strongly on the Darcy (Da) and Rayleigh (Ra) numbers. For a relatively low product of Ra {times} Da, the flow takes place primarily in the fluid layers, and heat transfer in the <span class="hlt">porous</span> layer is by conduction only. On other hand, fluid penetrating into a relatively highly permeable <span class="hlt">porous</span> layer has a significant impact on the natural convection flow patterns in the entire enclosure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/838252','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/838252"><span>Pore Scale Simulations of <span class="hlt">Rock</span> Deformation, Fracture, and Fluid Flow in Three Dimensions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wang, Herbert F.</p> <p>2005-04-01</p> <p>The pore-scale examination of <span class="hlt">rock</span> deformation and fluid flow consisted of three separate tasks. (1) New laboratory measurements were made of poroelastic properties of Berea sandstone and a new method was developed to measure both the poroelastic constants and the hydraulic conductivity on the same sample of <span class="hlt">rock</span> in a single test. (2) The second task was to develop constitutive theories of elastic and poroelastic properties of dual-porosity <span class="hlt">rocks</span> and <span class="hlt">rocks</span> with cracks. The new constitutive relations explain wave-velocity dispersion in <span class="hlt">fluid-saturated</span> <span class="hlt">rock</span> and the stiffening of shear modulus when dry <span class="hlt">rock</span> is saturated. (3) The third task involved pore-scale percolation modeling of two-phase fluid flow in granular media. The model properly simulates fractal geometries of nonwetting clusters and saturations for flow in unstable gradients. The percolation model was coupled with a water-vapor diffusion model to produce saturation maps in a <span class="hlt">rock</span> core during evaporative drying. The realistic patchy saturation was used in a heuristic model for predicting elastic properties of partially-saturated <span class="hlt">rock</span>, which mimicked laboratory results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGE....14..212A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGE....14..212A"><span>An integrated petrophysical and <span class="hlt">rock</span> physics analysis to improve reservoir characterization of Cretaceous sand intervals in Middle Indus Basin, Pakistan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Azeem, Tahir; Chun, Wang Yan; MonaLisa; Khalid, Perveiz; Xue Qing, Liu; Ehsan, Muhammad Irfan; Jawad Munawar, Muhammad; Wei, Xie</p> <p>2017-03-01</p> <p>The sand intervals of the Lower Goru Formation of the Cretaceous age, widely distributed in the Middle and Lower Indus Basin of Pakistan, are proven reservoirs. However, in the Sawan gas field of the Middle Indus Basin, these sandstone intervals are very deep and extremely heterogeneous in character, which makes it difficult to discriminate lithologies and <span class="hlt">fluid</span> <span class="hlt">saturation</span>. Based on petrophysical analysis and <span class="hlt">rock</span> physics modeling, an integrated approach is adopted to discriminate between lithologies and <span class="hlt">fluid</span> <span class="hlt">saturation</span> in the above-mentioned sand intervals. The seismic velocities are modeled using the Xu–White clay–sand mixing <span class="hlt">rock</span> physics model. The calibrated <span class="hlt">rock</span> physics model shows good consistency between measured and modeled velocities. The correlation between measured and modeled P and S wave velocities is 92.76% and 84.99%, respectively. This calibrated model has been successfully used to estimate other elastic parameters, even in those wells where both shear and sonic logs were missing. These estimated elastic parameters were cross-plotted to discriminate between the lithology and fluid content in the target zone. Cross plots clearly separate the shale, shaly sand, and gas-bearing sand clusters, which was not possible through conventional petrophysical analysis. These data clusters have been exported to the corresponding well for the purpose of interpolation between wells and to analyze the lateral and vertical variations in lithology and fluid content in the reservoir zone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/860283','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/860283"><span>CAPILLARY BARRIERS IN UNSATURATED FRACTURED <span class="hlt">ROCKS</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Y.S. Wu; W. Zhang; L. Pan; J. Hinds; G. Bodvarsson</p> <p>2000-10-01</p> <p>This work presents modeling studies investigating the effects of capillary barriers on fluid-flow and tracer-transport processes in the unsaturated zone of Yucca Mountain, Nevada, a potential site for storing high-level radioactive waste. These studies are designed to identify factors controlling the formation of capillary barriers and to estimate their effects on the extent of possible large-scale lateral flow in unsaturated fracture <span class="hlt">rocks</span>. The modeling approach is based on a continuum formulation of coupled multiphase fluid and tracer transport through fractured <span class="hlt">porous</span> <span class="hlt">rock</span>. Flow processes in fractured <span class="hlt">porous</span> <span class="hlt">rock</span> are described using a dual-continuum concept. In addition, approximate analytical solutions are developed and used for assessing capillary-barrier effects in fractured <span class="hlt">rocks</span>. This study indicates that under the current hydrogeologic conceptualization of Yucca Mountain, strong capillary-barrier effects exist for significantly diverting moisture flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992PhDT........66N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992PhDT........66N"><span>Micromechanics of Seismic Wave Propagation in Granular <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nihei, Kurt Toshimi</p> <p>1992-09-01</p> <p>This thesis investigates the details of seismic wave propagation in granular <span class="hlt">rocks</span> by examining the micromechanical processes which take place at the grain level. Grain contacts are identified as the primary sites of attenuation in dry and <span class="hlt">fluid-saturated</span> <span class="hlt">rocks</span>. In many sedimentary <span class="hlt">rocks</span> such as sandstones and limestones, the process of diagenesis leaves the grains only partially cemented together. When viewed at the micron scale, grain contacts are non-welded interfaces similar in nature to large scale joints and faults. Using a lumped properties approximation, the macroscopic properties of partially cemented grain contacts are modeled using a displacement-discontinuity boundary condition. This model is used to estimate the magnitude and the frequency dependence of the grain contact scattering attenuation for an idealized grain packing geometry. Ultrasonic P- and S-wave group velocity and attenuation measurements on sintered glass beads, alundum, and Berea sandstones were performed to determine the effects of stress, frequency, and pore fluid properties in granular materials with sintered and partially sintered grain contacts. P - and S-wave attenuation displayed the same overall trends for tests with n-decane, water, silicone oil, and glycerol. The magnitudes of the attenuation coefficients were, in general, higher for S-waves. The experimental measurements reveal that viscosity-dependent attenuation dominates in material with sintered grain contacts. Viscosity-dependent attenuation is also observed in Berea sandstone but only at hydrostatic stresses in excess of 15 MPa where the grain contacts are highly stiffened. Fluid surface chemistry-related attenuation was observed in Berea sandstone loaded uniaxially. These measurements suggest that attenuation in <span class="hlt">fluid-saturated</span> <span class="hlt">rocks</span> with partially cemented grain contacts is dependent on both the fluid properties and the state of stress at the grain contacts. A numerical method for simulating seismic wave propagation in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=mineral&pg=7&id=EJ914374','ERIC'); return false;" href="https://eric.ed.gov/?q=mineral&pg=7&id=EJ914374"><span>Art <span class="hlt">Rocks</span> with <span class="hlt">Rock</span> Art!</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Bickett, Marianne</p> <p>2011-01-01</p> <p>This article discusses <span class="hlt">rock</span> art which was the very first "art." <span class="hlt">Rock</span> art, such as the images created on the stone surfaces of the caves of Lascaux and Altimira, is the true origin of the canvas, paintbrush, and painting media. For there, within caverns deep in the earth, the first artists mixed animal fat, urine, and saliva with powdered minerals…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=bison+AND+bison&id=EJ914374','ERIC'); return false;" href="http://eric.ed.gov/?q=bison+AND+bison&id=EJ914374"><span>Art <span class="hlt">Rocks</span> with <span class="hlt">Rock</span> Art!</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Bickett, Marianne</p> <p>2011-01-01</p> <p>This article discusses <span class="hlt">rock</span> art which was the very first "art." <span class="hlt">Rock</span> art, such as the images created on the stone surfaces of the caves of Lascaux and Altimira, is the true origin of the canvas, paintbrush, and painting media. For there, within caverns deep in the earth, the first artists mixed animal fat, urine, and saliva with powdered minerals…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/962725','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/962725"><span>Fluid effects on seismic waves in hard <span class="hlt">rocks</span> with fractures and in soft granular media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Berryman, James G.</p> <p>2009-03-01</p> <p>When fractures in otherwise hard <span class="hlt">rocks</span> are filled with fluids (oil, gas, water, CO{sub 2}), the type and physical state of the fluid (liquid or gas) can make a large difference in the wave speeds and attenuation properties of seismic waves. The present work summarizes methods of deconstructing theses effects of fractures, together with any fluids contained within them, on wave propagation as observed in reflection seismic data. Additional studies of waves in <span class="hlt">fluid-saturated</span> granular media show that the behavior can be quite different from that for fractured media, since these materials are typically much softer mechanically than are the fractured <span class="hlt">rocks</span> (i.e., having a very small drained moduli). Important fluid effects in such media are often governed as much by fluid viscosity as by fluid bulk modulus.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22062366','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22062366"><span>A versatile facility for laboratory studies of viscoelastic and poroelastic behaviour of <span class="hlt">rocks</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jackson, Ian; Schijns, Heather; Schmitt, Douglas R.; Mu Junjie; Delmenico, Alison</p> <p>2011-06-15</p> <p>Novel laboratory equipment has been modified to allow both torsional and flexural oscillation measurements at sub-microstrain amplitudes, thereby providing seismic-frequency constraints on both the shear and compressional wave properties of cylindrical <span class="hlt">rock</span> specimens within the linear regime. The new flexural mode capability has been tested on experimental assemblies containing fused silica control specimens. Close consistency between the experimental data and the results of numerical modelling with both finite-difference and finite-element methods demonstrates the viability of the new technique. The capability to perform such measurements under conditions of independently controlled confining and pore-fluid pressure, with emerging strategies for distinguishing between local (squirt) and global (specimen-wide) fluid flow, will have particular application to the study of frequency-dependent seismic properties expected of cracked and <span class="hlt">fluid-saturated</span> <span class="hlt">rocks</span> of the Earth's upper crust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhFl...29b6601D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhFl...29b6601D"><span>Dissolution in anisotropic <span class="hlt">porous</span> media: Modelling convection regimes from onset to shutdown</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Paoli, Marco; Zonta, Francesco; Soldati, Alfredo</p> <p>2017-02-01</p> <p>In the present study, we use direct numerical simulations to examine the role of non-isotropic permeability on solutal convection in a <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> medium. The dense solute injected from the top boundary is driven downwards by gravity and follows a complex time-dependent dynamics. The process of solute dissolution, which is initially controlled by diffusion, becomes dominated by convection as soon as fingers appear, grow, and interact. The dense solute finally reaches the bottom boundary where, due to the prescribed impermeable boundary, it starts filling the domain so to enter the shutdown stage. We present the entire transient dynamics for large Rayleigh-Darcy numbers, Ra, and non-isotropic permeability. We also try to provide suitable and reliable models to parametrize it. With the conceptual setup presented here, we aim at mimicking the process of liquid CO2 sequestration into geological reservoirs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APhy...63..346A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APhy...63..346A"><span>Nonlinear acoustic spectroscopy of carbonate <span class="hlt">rocks</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Averbakh, V. S.; Bredikhin, V. V.; Lebedev, A. V.; Manakov, S. A.</p> <p>2017-05-01</p> <p>The paper presents the results of experimental research into the nonlinear acoustic properties of carbonate <span class="hlt">rocks</span> depending on saturation. The linear acoustic properties of the same sample depending on saturation were presented earlier in Physical Acoustics. The previously obtained data point to the isotropy of the material, which makes it possible to restrict analysis to only two vibration modes. Responses for finite deformations were measured for the longitudinal and shear modes of an isotropic sample, which made it possible to analyze the nonlinear properties of macroscopic deformations with a change in volume and pure displacement. A heretofore unknown feature of the response was revealed for finite deformation values; it is related to the occurrence of a jumplike transition from classical nonlinearity to a hysteresis type of nonlinearity. As well, the deformation amplitude corresponding to the transition depends on <span class="hlt">fluid</span> <span class="hlt">saturation</span>. We studied the slow relaxation that occurs after long-term excitation of a sample with a deformation amplitude on the order of 10-6. Data are presented on relaxation for deformation from pure displacement and deformation with a change in volume, which made it possible to isolate features related to the type of deformation and to compare the obtained data with the earlier published theoretical model. These data are compared with the results of other research groups.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA03698&hterms=Sedimentary+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DSedimentary%2Brocks','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA03698&hterms=Sedimentary+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DSedimentary%2Brocks"><span>Terby's <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2006-01-01</p> <p><p/> 27 January 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the light-toned, layered, sedimentary <span class="hlt">rock</span> outcrops in northern Terby Crater. Terby is located along the north edge of Hellas Planitia. The sedimentary <span class="hlt">rocks</span> might have been deposited in a greater, Hellas-filling sea -- or not. Today, the <span class="hlt">rocks</span> are partly covered by dark-toned sediment and debris. <p/> <i>Location near</i>: 27.2oS, 285.3oW <i>Image width</i>: 3 km (1.9 mi) <i>Illumination from</i>: upper left <i>Season</i>: Southern Summer</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA05060&hterms=Scientists+lies&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DScientists%2Blies','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA05060&hterms=Scientists+lies&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DScientists%2Blies"><span>Opportunity <span class="hlt">Rocks</span>!</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>This high-resolution image captured by the Mars Exploration Rover Opportunity's panoramic camera shows in superb detail a portion of the puzzling <span class="hlt">rock</span> outcropping that scientists are eagerly planning to investigate. Presently, Opportunity is on its lander facing northeast; the outcropping lies to the northwest. These layered <span class="hlt">rocks</span> measure only 10 centimeters (4 inches) tall and are thought to be either volcanic ash deposits or sediments carried by water or wind. The small <span class="hlt">rock</span> in the center is about the size of a golf ball.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4353039','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4353039"><span>Freeze fracturing of elastic <span class="hlt">porous</span> media: a mathematical model</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Vlahou, I.; Worster, M. G.</p> <p>2015-01-01</p> <p>We present a mathematical model of the fracturing of water-saturated <span class="hlt">rocks</span> and other <span class="hlt">porous</span> materials in cold climates. Ice growing inside <span class="hlt">porous</span> <span class="hlt">rocks</span> causes large pressures to develop that can significantly damage the <span class="hlt">rock</span>. We study the growth of ice inside a penny-shaped cavity in a water-saturated <span class="hlt">porous</span> <span class="hlt">rock</span> and the consequent fracturing of the medium. Premelting of the ice against the <span class="hlt">rock</span>, which results in thin films of unfrozen water forming between the ice and the <span class="hlt">rock</span>, is one of the dominant processes of <span class="hlt">rock</span> fracturing. We find that the fracture toughness of the <span class="hlt">rock</span>, the size of pre-existing faults and the undercooling of the environment are the main parameters determining the susceptibility of a medium to fracturing. We also explore the dependence of the growth rates on the permeability and elasticity of the medium. Thin and fast-fracturing cracks are found for many types of <span class="hlt">rocks</span>. We consider how the growth rate can be limited by the existence of pore ice, which decreases the permeability of a medium, and propose an expression for the effective ‘frozen’ permeability. PMID:25792954</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/869296','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/869296"><span>Method and apparatus for determining two-phase flow in <span class="hlt">rock</span> fracture</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Persoff, Peter; Pruess, Karsten; Myer, Larry</p> <p>1994-01-01</p> <p>An improved method and apparatus as disclosed for measuring the permeability of multiple phases through a <span class="hlt">rock</span> fracture. The improvement in the method comprises delivering the respective phases through manifolds to uniformly deliver and collect the respective phases to and from opposite edges of the <span class="hlt">rock</span> fracture in a distributed manner across the edge of the fracture. The improved apparatus comprises first and second manifolds comprising bores extending within <span class="hlt">porous</span> blocks parallel to the <span class="hlt">rock</span> fracture for distributing and collecting the wetting phase to and from surfaces of the <span class="hlt">porous</span> blocks, which respectively face the opposite edges of the <span class="hlt">rock</span> fracture. The improved apparatus further comprises other manifolds in the form of plenums located adjacent the respective <span class="hlt">porous</span> blocks for uniform delivery of the non-wetting phase to parallel grooves disposed on the respective surfaces of the <span class="hlt">porous</span> blocks facing the opposite edges of the <span class="hlt">rock</span> fracture and generally perpendicular to the <span class="hlt">rock</span> fracture.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA03773.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA03773.html"><span>White <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2002-05-21</p> <p>White <span class="hlt">Rock</span> is the unofficial name for this unusual landform which was first observed during NASA Mariner 9 mission in the early 1970 and is now shown here in an image from NASA Mars Odyssey spacecraft.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA00987&hterms=Gardens&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DGardens','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA00987&hterms=Gardens&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DGardens"><span><span class="hlt">Rock</span> Garden</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1997-01-01</p> <p>This false color composite image of the <span class="hlt">Rock</span> Garden shows the <span class="hlt">rocks</span> 'Shark' and 'Half Dome' at upper left and middle, respectively. Between these two large <span class="hlt">rocks</span> is a smaller <span class="hlt">rock</span> (about 0.20 m wide, 0.10 m high, and 6.33 m from the Lander) that was observed close-up with the Sojourner rover (see PIA00989).<p/>Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA07018&hterms=granules&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dgranules','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA07018&hterms=granules&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dgranules"><span>'Lutefisk' <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/> [figure removed for brevity, see original site] Figure 1 <p/> NASA's Mars Exploration Rover Spirit used its panoramic camera to take this image of a <span class="hlt">rock</span> called 'Lutefisk' on the rover's 286th martian day (Oct. 22, 2004). The surface of the <span class="hlt">rock</span> is studded with rounded granules of apparently more-resistant material up to several millimeters (0.1 inch) or more across. The visible portion of Lutefisk is about 25 centimeters (10 inches) across.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AdWR...34..205F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AdWR...34..205F"><span>Non-Fickian mass transport in fractured <span class="hlt">porous</span> media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fomin, Sergei A.; Chugunov, Vladimir A.; Hashida, Toshiyuki</p> <p>2011-02-01</p> <p>The paper provides an introduction to fundamental concepts of mathematical modeling of mass transport in fractured <span class="hlt">porous</span> heterogeneous <span class="hlt">rocks</span>. Keeping aside many important factors that can affect mass transport in subsurface, our main concern is the multi-scale character of the <span class="hlt">rock</span> formation, which is constituted by <span class="hlt">porous</span> domains dissected by the network of fractures. Taking into account the well-documented fact that <span class="hlt">porous</span> <span class="hlt">rocks</span> can be considered as a fractal medium and assuming that sizes of pores vary significantly (i.e. have different characteristic scales), the fractional-order differential equations that model the anomalous diffusive mass transport in such type of domains are derived and justified analytically. Analytical solutions of some particular problems of anomalous diffusion in the fractal media of various geometries are obtained. Extending this approach to more complex situation when diffusion is accompanied by advection, solute transport in a fractured <span class="hlt">porous</span> medium is modeled by the advection-dispersion equation with fractional time derivative. In the case of confined fractured <span class="hlt">porous</span> aquifer, accounting for anomalous non-Fickian diffusion in the surrounding <span class="hlt">rock</span> mass, the adopted approach leads to introduction of an additional fractional time derivative in the equation for solute transport. The closed-form solutions for concentrations in the aquifer and surrounding <span class="hlt">rocks</span> are obtained for the arbitrary time-dependent source of contamination located in the inlet of the aquifer. Based on these solutions, different regimes of contamination of the aquifers with different physical properties can be readily modeled and analyzed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.3246S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.3246S"><span>Parallel Program Systems for the Analysis of Wave Processes in Elastic-Plastic, Granular, <span class="hlt">Porous</span> and Multi-Blocky Media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sadovskaya, Oxana; Sadovskii, Vladimir</p> <p>2017-04-01</p> <p>-dimensional systems of equations at the stages of splitting method. The parallelizing of computations is carried out using the MPI library and the SPMD technology. The data exchange between processors occurs at step "predictor" of the finite-difference scheme. Program systems allow simulate the propagation of waves produced by external mechanical effects in a medium, aggregated of arbitrary number of heterogeneous blocks. Some computations of dynamic problems with and without taking into account the moment properties of a material were performed on clusters of ICM SB RAS (Krasnoyarsk) and JSCC RAS (Moscow). Parallel program systems 2Dyn_Granular, 3Dyn_Granular, 2Dyn_Cosserat, 3Dyn_Cosserat and 2Dyn_Blocks_MPI for numerical solution of 2D and 3D elastic-plastic problems of the dynamics of granular media and problems of the Cosserat elasticity theory, as well as for modeling of the dynamic processes in multi-blocky media with pliant viscoelastic, <span class="hlt">porous</span> and <span class="hlt">fluid-saturated</span> interlayers on cluster systems were registered by Rospatent.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA05838&hterms=blisters&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dblisters','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA05838&hterms=blisters&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dblisters"><span>Evidence of Ancient Blisters in <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/>This image from the panoramic camera on the Mars Exploration Rover Spirit shows scoriaceous <span class="hlt">rocks</span> (<span class="hlt">rocks</span> containing holes or cavities) on the ground, as well as a transition from rocky terrain (foreground) to smoother terrain (background). Spirit is heading toward the smoother terrain on its way to the 'Columbia Hills.' The holes in some of the <span class="hlt">rocks</span> may have resulted from 'blisters' formed by water vapor as it escaped lava. This indicates that the <span class="hlt">rocks</span> were chilled atop an ancient lava flow. <span class="hlt">Porous</span> <span class="hlt">rocks</span> such as these, now appearing in abundance, have not been seen since early in the mission. Scientists believe they may have been covered by crater ejecta. This image was taken on sol 110 (April 24, 2004) at a region dubbed 'site 35.'</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA05838&hterms=blister&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dblister','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA05838&hterms=blister&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dblister"><span>Evidence of Ancient Blisters in <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/>This image from the panoramic camera on the Mars Exploration Rover Spirit shows scoriaceous <span class="hlt">rocks</span> (<span class="hlt">rocks</span> containing holes or cavities) on the ground, as well as a transition from rocky terrain (foreground) to smoother terrain (background). Spirit is heading toward the smoother terrain on its way to the 'Columbia Hills.' The holes in some of the <span class="hlt">rocks</span> may have resulted from 'blisters' formed by water vapor as it escaped lava. This indicates that the <span class="hlt">rocks</span> were chilled atop an ancient lava flow. <span class="hlt">Porous</span> <span class="hlt">rocks</span> such as these, now appearing in abundance, have not been seen since early in the mission. Scientists believe they may have been covered by crater ejecta. This image was taken on sol 110 (April 24, 2004) at a region dubbed 'site 35.'</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1511914L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1511914L"><span>Instability of fluid flow over saturated <span class="hlt">porous</span> medium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lyubimova, Tatyana; Kolchanova, Ekaterina; Lyubimov, Dmitry</p> <p>2013-04-01</p> <p>We investigate the stability of a fluid flow over a saturated <span class="hlt">porous</span> medium. The problem is of importance due to the applications to washing out of contaminants from the bottom layer of vegetation, whose properties are similar to the properties of <span class="hlt">porous</span> medium. In the case of <span class="hlt">porous</span> medium with the relatively high permeability and porosity the flow involves a part of the <span class="hlt">fluid</span> <span class="hlt">saturating</span> the <span class="hlt">porous</span> medium, with the tangential fluid velocity drop occurring because of the resistance of the solid matrix. The drop leads to the instability analogous to Kelvin-Helmholtz one accompanied by the formation of travelling waves. In the present paper we consider a two-layer system consisting of a pure fluid layer and a <span class="hlt">porous</span> layer saturated by the fluid located underneath. The system is bounded by a rigid surface at the bottom and a non-deformable free surface at the top. It is under the gravity and inclined at a slight angle to the horizontal axis. The boundary conditions at the interface between the fluid and <span class="hlt">porous</span> layers are the continuity of fluid velocities and the balance of normal and tangential stresses taking into account the resistance of the solid matrix with respect to the fluid flow near the interface [1-2]. The problem is solved in the framework of the Brinkman model applying the classical shooting algorithm with orthogonalization. The stability boundaries of the stationary fluid flow over the saturated <span class="hlt">porous</span> medium with respect to the small oscillatory perturbations are obtained for the various values of the Darcy number and the ratio of the <span class="hlt">porous</span> layer thickness to the full thickness of the system d. It was shown that at the d > 0.5 with increasing the <span class="hlt">porous</span> layer thickness (or with decreasing of the fluid layer thickness) the stability threshold rises. This is because of the fact that the instability is primarily caused by perturbations located in the fluid layer. At the d < 0.5 the reduction of the <span class="hlt">porous</span> layer thickness leads to the stability threshold</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA06920&hterms=Escher&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DEscher','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA06920&hterms=Escher&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DEscher"><span>'Wopmay' <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/> This approximate true-color image taken by NASA's Mars Exploration Rover Opportunity shows an unusual, lumpy <span class="hlt">rock</span> informally named 'Wopmay' on the lower slopes of 'Endurance Crater.' The <span class="hlt">rock</span> was named after the Canadian bush pilot Wilfrid Reid 'Wop' May. Like 'Escher' and other <span class="hlt">rocks</span> dotting the bottom of Endurance, scientists believe the lumps in Wopmay may be related to cracking and alteration processes, possibly caused by exposure to water. The area between intersecting sets of cracks eroded in a way that created the lumpy appearance. Rover team members plan to drive Opportunity over to Wopmay for a closer look in coming sols. This image was taken by the rover's panoramic camera on sol 248 (Oct. 4, 2004), using its 750-, 530- and 480-nanometer filters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999JGR...10420021R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999JGR...10420021R"><span>Streaming potential in <span class="hlt">porous</span> media: 1. Theory of the zeta potential</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Revil, A.; Pezard, P. A.; Glover, P. W. J.</p> <p>1999-09-01</p> <p>Electrokinetic phenomena are responsible for several electrical properties of <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> materials. Geophysical applications of these phenomena could include the use of streaming potentials for mapping subsurface fluid flow, the study of hydrothermal activity of geothermal areas, and in the context of earthquake prediction and volcanic activity forecasting, for example. The key parameter of electrokinetic phenomena is the ξ potential, which represents roughly the electrical potential at the mineral/water interface. We consider silica-dominated <span class="hlt">porous</span> materials filled with a binary symmetric 1:1 electrolyte such as NaCl. When in contact with this electrolyte, the silica/water interface gets an excess of charge through chemical reactions. Starting with these chemical reactions, we derive analytical equations for the ξ potential and the specific surface conductance. These equations can be used to predict the variations of these parameters with the pore fluid salinity, temperature, and pH (within a /pH range of 6-8). The input parameters to these equations fall into two categories: (1) mineral/fluid interaction geochemistry (including mineral surface site density and surface equilibrium constants of mineral/fluid reactions), and (2) pore fluid /pH, salinity, and temperature. The ξ potential is shown to increase with increasing temperature and pH and to decrease with increasing salinity. The proposed model is in agreement with available experimental data. The application of this model to electric potentials generated in <span class="hlt">porous</span> media by fluid flow is explored in the companion paper.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010PhRvE..82b6305A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010PhRvE..82b6305A"><span>Oscillation-induced displacement patterns in a two-dimensional <span class="hlt">porous</span> medium: A lattice Boltzmann study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aursjø, Olav; Knudsen, Henning Arendt; Flekkøy, Eirik G.; Måløy, Knut Jørgen</p> <p>2010-08-01</p> <p>We present a numerical study of the statistical behavior of a two-phase flow in a two-dimensional <span class="hlt">porous</span> medium subjected to an oscillatory acceleration transverse to the overall direction of flow. A viscous nonwetting fluid is injected into a <span class="hlt">porous</span> medium filled with a more viscous wetting fluid. During the whole process sinusoidal oscillations of constant amplitude and frequency accelerates the <span class="hlt">porous</span> medium sideways, perpendicular to the overall direction of flow. The invasion process displays a transient behavior where the saturation of the defending fluid decreases, before it enters a state of irreducible wetting <span class="hlt">fluid</span> <span class="hlt">saturation</span>, where there is no net transport of defending fluid toward the outlet of the system. In this state the distribution of sizes of the remaining clusters are observed to obey a power law with an exponential cutoff. The cutoff cluster size is found to be determined by the flow and oscillatory stimulation parameters. This cutoff size is also shown to be directly related to the extracted amount of defending fluid. Specifically, the results show that the oscillatory acceleration of the system leads to potentially a large increase in extracted wetting fluid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20866903','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20866903"><span>Oscillation-induced displacement patterns in a two-dimensional <span class="hlt">porous</span> medium: a lattice Boltzmann study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Aursjø, Olav; Knudsen, Henning Arendt; Flekkøy, Eirik G; Måløy, Knut Jørgen</p> <p>2010-08-01</p> <p>We present a numerical study of the statistical behavior of a two-phase flow in a two-dimensional <span class="hlt">porous</span> medium subjected to an oscillatory acceleration transverse to the overall direction of flow. A viscous nonwetting fluid is injected into a <span class="hlt">porous</span> medium filled with a more viscous wetting fluid. During the whole process sinusoidal oscillations of constant amplitude and frequency accelerates the <span class="hlt">porous</span> medium sideways, perpendicular to the overall direction of flow. The invasion process displays a transient behavior where the saturation of the defending fluid decreases, before it enters a state of irreducible wetting <span class="hlt">fluid</span> <span class="hlt">saturation</span>, where there is no net transport of defending fluid toward the outlet of the system. In this state the distribution of sizes of the remaining clusters are observed to obey a power law with an exponential cutoff. The cutoff cluster size is found to be determined by the flow and oscillatory stimulation parameters. This cutoff size is also shown to be directly related to the extracted amount of defending fluid. Specifically, the results show that the oscillatory acceleration of the system leads to potentially a large increase in extracted wetting fluid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=dairy+AND+farms&pg=2&id=EJ754080','ERIC'); return false;" href="http://eric.ed.gov/?q=dairy+AND+farms&pg=2&id=EJ754080"><span>Classic <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Beem, Edgar Allen</p> <p>2004-01-01</p> <p>While "early college" programs designed for high-school-age students are beginning to proliferate nationwide, a small New England school has been successfully educating teens for nearly four decades. In this article, the author features Simon's <span class="hlt">Rock</span>, a small liberal arts college located in the Great Barrington, Massachusetts, that has…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22782804','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22782804"><span>Is biodegradable waste a <span class="hlt">porous</span> environment? A review.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Agostini, Francesco; Sundberg, Cecilia; Navia, Rodrigo</p> <p>2012-10-01</p> <p>This article presents a review of the <span class="hlt">porous</span> physical characteristics, phenomena and simulation models so far investigated and applied in the management of biodegradable wastes (BW), summarising the main properties of <span class="hlt">porous</span> media and the dynamics of fluids within its voids. The aim is to highlight how the description of biodegradable wastes as <span class="hlt">porous</span> media and the use of <span class="hlt">porous</span> media models can facilitate the development of new sustainable and affordable technologies for BW recycling. However, it is pointed out how the lack of physical experimental data and of tailored modelling tools has so far hampered the use of this approach. Therefore, it is suggested that a simpler way to design and implement modelling tools simulating BW treatment technologies is by modifying available models designed originally for other <span class="hlt">porous</span> media, such as soil and <span class="hlt">rock</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA00925&hterms=mermaid&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmermaid','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA00925&hterms=mermaid&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmermaid"><span>Poohbear <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1997-01-01</p> <p>This image, taken by Sojourner's front right camera, was taken when the rover was next to Poohbear (<span class="hlt">rock</span> at left) and Piglet (not seen) as it looked out toward Mermaid Dune. The textures differ from the foreground soil containing a sorted mix of small <span class="hlt">rocks</span>, fines and clods, from the area a bit ahead of the rover where the surface is covered with a bright drift material. Soil experiments where the rover wheels dug in the soil revealed that the cloudy material exists underneath the drift.<p/>Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA03773&hterms=rock+salt&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Drock%2Bsalt','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA03773&hterms=rock+salt&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Drock%2Bsalt"><span>White <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>(Released 19 April 2002) The Science 'White <span class="hlt">Rock</span>' is the unofficial name for this unusual landform which was first observed during the Mariner 9 mission in the early 1970's. As later analysis of additional data sets would show, White <span class="hlt">Rock</span> is neither white nor dense <span class="hlt">rock</span>. Its apparent brightness arises from the fact that the material surrounding it is so dark. Images from the Mars Global Surveyor MOC camera revealed dark sand dunes surrounding White <span class="hlt">Rock</span> and on the floor of the troughs within it. Some of these dunes are just apparent in the THEMIS image. Although there was speculation that the material composing White <span class="hlt">Rock</span> could be salts from an ancient dry lakebed, spectral data from the MGS TES instrument did not support this claim. Instead, the White <span class="hlt">Rock</span> deposit may be the erosional remnant of a previously more continuous occurrence of air fall sediments, either volcanic ash or windblown dust. The THEMIS image offers new evidence for the idea that the original deposit covered a larger area. Approximately 10 kilometers to the southeast of the main deposit are some tiny knobs of similarly bright material preserved on the floor of a small crater. Given that the eolian erosion of the main White <span class="hlt">Rock</span> deposit has produced isolated knobs at its edges, it is reasonable to suspect that the more distant outliers are the remnants of a once continuous deposit that stretched at least to this location. The fact that so little remains of the larger deposit suggests that the material is very easily eroded and simply blows away. The Story Fingers of hard, white <span class="hlt">rock</span> seem to jut out like icy daggers across a moody Martian surface, but appearances can be deceiving. These bright, jagged features are neither white, nor icy, nor even hard and rocky! So what are they, and why are they so different from the surrounding terrain? Scientists know that you can't always trust what your eyes see alone. You have to use other kinds of science instruments to measure things that our eyes can</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA00925&hterms=Mermaids&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMermaids','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA00925&hterms=Mermaids&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMermaids"><span>Poohbear <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1997-01-01</p> <p>This image, taken by Sojourner's front right camera, was taken when the rover was next to Poohbear (<span class="hlt">rock</span> at left) and Piglet (not seen) as it looked out toward Mermaid Dune. The textures differ from the foreground soil containing a sorted mix of small <span class="hlt">rocks</span>, fines and clods, from the area a bit ahead of the rover where the surface is covered with a bright drift material. Soil experiments where the rover wheels dug in the soil revealed that the cloudy material exists underneath the drift.<p/>Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA06078&hterms=granules&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dgranules','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA06078&hterms=granules&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dgranules"><span>Meridiani <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2005-01-01</p> <p><p/> 16 September 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the complex surfaces of some of the light- and intermediate-toned sedimentary <span class="hlt">rock</span> exposed by erosion in eastern Sinus Meridiani. Similar <span class="hlt">rocks</span> occur at the Mars Exploration Rover, Opportunity, site, but they are largely covered by windblown sand and granules. The dark feature with a rayed pattern is the product of a meteor impact. <p/> <i>Location near</i>: 0.8oN, 355.2oW <i>Image width</i>: width: 3 km (1.9 mi) <i>Illumination from</i>: lower left <i>Season</i>: Northern Autumn</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA04167&hterms=Sedimentary+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DSedimentary%2Brocks','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA04167&hterms=Sedimentary+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DSedimentary%2Brocks"><span>Terby's <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2005-01-01</p> <p><p/> 25 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned, layered, sedimentary <span class="hlt">rock</span> outcrops in the crater, Terby. The crater is located on the north rim of Hellas Basin. If one could visit the <span class="hlt">rocks</span> in Terby, one might learn from them whether they formed in a body of water. It is possible, for example, that Terby was a bay in a larger, Hellas-wide sea. <p/> <i>Location near</i>: 27.9oS, 285.7oW <i>Image width</i>: width: 3 km (1.9 mi) <i>Illumination from</i>: upper left <i>Season</i>: Southern Winter</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA03773&hterms=black+white+photography&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dblack%2Bwhite%2Bphotography','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA03773&hterms=black+white+photography&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dblack%2Bwhite%2Bphotography"><span>White <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>(Released 19 April 2002) The Science 'White <span class="hlt">Rock</span>' is the unofficial name for this unusual landform which was first observed during the Mariner 9 mission in the early 1970's. As later analysis of additional data sets would show, White <span class="hlt">Rock</span> is neither white nor dense <span class="hlt">rock</span>. Its apparent brightness arises from the fact that the material surrounding it is so dark. Images from the Mars Global Surveyor MOC camera revealed dark sand dunes surrounding White <span class="hlt">Rock</span> and on the floor of the troughs within it. Some of these dunes are just apparent in the THEMIS image. Although there was speculation that the material composing White <span class="hlt">Rock</span> could be salts from an ancient dry lakebed, spectral data from the MGS TES instrument did not support this claim. Instead, the White <span class="hlt">Rock</span> deposit may be the erosional remnant of a previously more continuous occurrence of air fall sediments, either volcanic ash or windblown dust. The THEMIS image offers new evidence for the idea that the original deposit covered a larger area. Approximately 10 kilometers to the southeast of the main deposit are some tiny knobs of similarly bright material preserved on the floor of a small crater. Given that the eolian erosion of the main White <span class="hlt">Rock</span> deposit has produced isolated knobs at its edges, it is reasonable to suspect that the more distant outliers are the remnants of a once continuous deposit that stretched at least to this location. The fact that so little remains of the larger deposit suggests that the material is very easily eroded and simply blows away. The Story Fingers of hard, white <span class="hlt">rock</span> seem to jut out like icy daggers across a moody Martian surface, but appearances can be deceiving. These bright, jagged features are neither white, nor icy, nor even hard and rocky! So what are they, and why are they so different from the surrounding terrain? Scientists know that you can't always trust what your eyes see alone. You have to use other kinds of science instruments to measure things that our eyes can</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA03197&hterms=geologist&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dgeologist','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA03197&hterms=geologist&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dgeologist"><span>White <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2005-01-01</p> <p><p/> 14 November 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of the famous 'White <span class="hlt">Rock</span>' feature in Pollack Crater in the Sinus Sabaeus region of Mars. The light-toned <span class="hlt">rock</span> is not really white, but its light tone caught the eye of Mars geologists as far back as 1972, when it was first spotted in images acquired by Mariner 9. The light-toned materials are probably the remains of a suite of layered sediments that once spread completely across the interior of Pollack Crater. Dark materials in this image include sand dunes and large ripples. <p/> <i>Location near</i>: 8.1oS, 335.1oW <i>Image width</i>: width: 3 km (1.9 mi) <i>Illumination from</i>: lower left <i>Season</i>: Southern Summer</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA21204.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA21204.html"><span>Rafted <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2016-11-09</p> <p>This area of Amazonis Planitia to the west of the large volcano Olympus Mons was once flooded with lava. A huge eruption flowed out across the relatively flat landscape. Sometimes called "flood basalt," the lava surface quickly cooled and formed a thin crust of solidified <span class="hlt">rock</span> that was pushed along with the flowing hot liquid <span class="hlt">rock</span>. Hills and mounds that pre-dated the flooding eruption became surrounded, forming obstructions to the relentless march of lava. In this image, these obstructions appeared to have poked up and sliced through the lava crust as the molten <span class="hlt">rock</span> and crust moved together from west to east, over and past the stationary mounds. The result is a series of parallel grooves or channels with the obstructing mound remaining at the western end as the flow came to rest. From such images scientists can reconstruct the direction of the lava flow, potentially tracing it back to the source vent. http://photojournal.jpl.nasa.gov/catalog/PIA21204</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhDT........66Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhDT........66Y"><span>Ultrasonic Nondestructive Characterization of <span class="hlt">Porous</span> Materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Ningli</p> <p>2011-12-01</p> <p>Wave propagation in <span class="hlt">porous</span> media is studied in a wide range of technological applications. In the manufacturing industry, determining porosity of materials in the manufacturing process is required for strict quality control. In the oil industry, acoustic signals and seismic surveys are used broadly to determine the physical properties of the reservoir <span class="hlt">rock</span> which is a <span class="hlt">porous</span> media filled with oil or gas. In <span class="hlt">porous</span> noise control materials, a precise prediction of sound absorption with frequency and evaluation of tortuosity are necessary. Ultrasonic nondestructive methods are a very important tool for characterization of <span class="hlt">porous</span> materials. The dissertation deals with two types of <span class="hlt">porous</span> media: materials with relatively low and closed porosity and materials with comparatively high and open porosity. Numerical modeling, Finite Element simulations and experimental characterization are all discussed in this dissertation. First, ultrasonic scattering is used to determine the porosity in <span class="hlt">porous</span> media with closed pores. In order get a relationship between the porosity in <span class="hlt">porous</span> materials and ultrasonic scattering independently and to increase the sensitivity to obtain scattering information, ultrasonic imaging methods are applied and acoustic waves are focused by an acoustic lens. To verify the technique, engineered <span class="hlt">porous</span> acrylic plates with varying porosity are measured by ultrasonic scanning and ultrasonic array sensors. Secondly, a laser based ultrasonic technique is explored for predicting the mechanical integrity and durability of cementitious materials. The technique used involves the measurement of the phase velocity of fast and slow longitudinal waves in water saturated cement paste. The slow wave velocity is related to the specimen's tortuosity. The fast wave speed is dependent on the elastic properties of <span class="hlt">porous</span> solid. Experimental results detailing the generation and detection of fast and slow wave waves in freshly prepared and aged water-saturated cement samples</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3639501','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3639501"><span><span class="hlt">Porous</span> Shape Memory Polymers</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hearon, Keith; Singhal, Pooja; Horn, John; Small, Ward; Olsovsky, Cory; Maitland, Kristen C.; Wilson, Thomas S.; Maitland, Duncan J.</p> <p>2013-01-01</p> <p><span class="hlt">Porous</span> shape memory polymers (SMPs) include foams, scaffolds, meshes, and other polymeric substrates that possess <span class="hlt">porous</span> three-dimensional macrostructures. <span class="hlt">Porous</span> SMPs exhibit active structural and volumetric transformations and have driven investigations in fields ranging from biomedical engineering to aerospace engineering to the clothing industry. The present review article examines recent developments in <span class="hlt">porous</span> SMPs, with focus given to structural and chemical classification, methods of characterization, and applications. We conclude that the current body of literature presents <span class="hlt">porous</span> SMPs as highly interesting smart materials with potential for industrial use. PMID:23646038</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/14827','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/14827"><span>Tailored <span class="hlt">Porous</span> Materials</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>BARTON,THOMAS J.; BULL,LUCY M.; KLEMPERER,WALTER G.; LOY,DOUGLAS A.; MCENANEY,BRIAN; MISONO,MAKOTO; MONSON,PETER A.; PEZ,GUIDO; SCHERER,GEORGE W.; VARTULI,JAMES C.; YAGHI,OMAR M.</p> <p>1999-11-09</p> <p>Tailoring of <span class="hlt">porous</span> materials involves not only chemical synthetic techniques for tailoring microscopic properties such as pore size, pore shape, pore connectivity, and pore surface reactivity, but also materials processing techniques for tailoring the meso- and the macroscopic properties of bulk materials in the form of fibers, thin films and monoliths. These issues are addressed in the context of five specific classes of <span class="hlt">porous</span> materials: oxide molecular sieves, <span class="hlt">porous</span> coordination solids, <span class="hlt">porous</span> carbons, sol-gel derived oxides, and <span class="hlt">porous</span> heteropolyanion salts. Reviews of these specific areas are preceded by a presentation of background material and review of current theoretical approaches to adsorption phenomena. A concluding section outlines current research needs and opportunities.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23646038','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23646038"><span><span class="hlt">Porous</span> Shape Memory Polymers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hearon, Keith; Singhal, Pooja; Horn, John; Small, Ward; Olsovsky, Cory; Maitland, Kristen C; Wilson, Thomas S; Maitland, Duncan J</p> <p>2013-02-04</p> <p><span class="hlt">Porous</span> shape memory polymers (SMPs) include foams, scaffolds, meshes, and other polymeric substrates that possess <span class="hlt">porous</span> three-dimensional macrostructures. <span class="hlt">Porous</span> SMPs exhibit active structural and volumetric transformations and have driven investigations in fields ranging from biomedical engineering to aerospace engineering to the clothing industry. The present review article examines recent developments in <span class="hlt">porous</span> SMPs, with focus given to structural and chemical classification, methods of characterization, and applications. We conclude that the current body of literature presents <span class="hlt">porous</span> SMPs as highly interesting smart materials with potential for industrial use.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012FlDyR..44c1415O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012FlDyR..44c1415O"><span>Analytical and numerical stability analysis of Soret-driven convection in a horizontal <span class="hlt">porous</span> layer: the effect of conducting bounding plates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ouattara, B.; Khouzam, A.; Mojtabi, A.; Charrier-Mojtabi, M. C.</p> <p>2012-06-01</p> <p>The aim of this study was to investigate the effect of conducting boundaries on the onset of convection in a binary <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> layer. The isotropic saturated <span class="hlt">porous</span> layer is bounded by two impermeable but thermally conducting plates, subjected to a constant heat flux. These plates have identical conductivity. Moreover, the conductivity of the plates is generally different from the <span class="hlt">porous</span> layer conductivity. The overall layer is of large extent in both horizontal directions. The problem is governed by seven dimensionless parameters, namely the normalized porosity of the medium ɛ, the ratio of plates over the <span class="hlt">porous</span> layer thickness δ and their relative thermal conductivities ratio d, the separation ratio δ, the Lewis number Le and thermal Rayleigh number Ra. In this work, an analytical and numerical stability analysis is performed. The equilibrium solution is found to lose its stability via a stationary bifurcation or a Hopf bifurcation depending on the values of the dimensionless parameters. For the long-wavelength mode, the critical Rayleigh number is obtained as Racs=12(1+2dδ )/[1+ψ (2dδLe+Le+1)] and kcs=0 for ψ> ψ uni> 0. This work extends an earlier paper by Mojtabi and Rees (2011 Int. J. Heat Mass Transfer 54 293-301) who considered a configuration where the <span class="hlt">porous</span> layer is saturated by a pure fluid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/7023753','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7023753"><span>Delineation of wellhead protection areas in fractured <span class="hlt">rocks</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bradbu, K.R.; Muldoon, M.A.; Zaporozec, A.; Levy, J.</p> <p>1991-06-01</p> <p>In 1989, the Wisconsin Geological and Natural History Survey prepared the report under an agreement with the Environmental Protection Agency to evaluate methods for wellhead protection area (WHPA) delineation in unconfined fractured-<span class="hlt">rock</span> aquifers. Two fractured-<span class="hlt">rock</span> settings were selected for the study: Precambrian crystalline <span class="hlt">rocks</span> in central Wisconsin and Silurian dolomite in northeastern Wisconsin. The methods tested ranged from simple approaches to complex computer models. Four WHPA delineation approaches are suggested for unconfined fractured-<span class="hlt">rock</span> aquifers that do not behave as <span class="hlt">porous</span> media.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010045304&hterms=inertia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dinertia','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010045304&hterms=inertia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dinertia"><span>Thermal Inertia of <span class="hlt">Rocks</span> and <span class="hlt">Rock</span> Populations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Golombek, M. P.; Jakosky, B. M.; Mellon, M. T.</p> <p>2001-01-01</p> <p>The effective thermal inertia of <span class="hlt">rock</span> populations on Mars and Earth is derived from a model of effective inertia versus <span class="hlt">rock</span> diameter. Results allow a parameterization of the effective <span class="hlt">rock</span> inertia versus <span class="hlt">rock</span> abundance and bulk and fine component inertia. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA03090&hterms=Sedimentary+rocks&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSedimentary%2Brocks','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA03090&hterms=Sedimentary+rocks&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSedimentary%2Brocks"><span>Sedimentary <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2005-01-01</p> <p><p/> 6 November 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows outcrops of sedimentary <span class="hlt">rocks</span> in a crater located just north of the Sinus Meridiani region. Perhaps the crater was once the site of a martian lake. <p/> <i>Location near</i>: 2.9oN, 359.0oW <i>Image width</i>: width: 3 km (1.9 mi) <i>Illumination from</i>: lower left <i>Season</i>: Northern Autumn</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15833644','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15833644"><span>Displacement propagators of brine flowing within different types of sedimentary <span class="hlt">rock</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Verganelakis, Dimitris A; Crawshaw, John; Johns, Michael L; Mantle, Michael D; Scheven, Ulrich; Sederman, Andrew J; Gladden, Lynn F</p> <p>2005-02-01</p> <p>This paper explores the correlation between different microstructural characteristics of <span class="hlt">porous</span> sedimentary <span class="hlt">rocks</span> and the flow properties of a Newtonian infiltrating fluid. Preliminary results of displacement propagator measurements of brine solution flowing through two types of sedimentary <span class="hlt">rock</span> cores are reported. The two types of <span class="hlt">rocks</span>, Bentheimer and Portland, are characterized by different porosities, pore-size distributions and permeabilities. Propagators have been measured for brine flow rates of 1 and 5 ml/min. Significant differences are seen between the propagators recorded for the two <span class="hlt">rocks</span>, and these are related to the spatial distribution of porosity within these <span class="hlt">porous</span> media.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003GeoRL..30.1291M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003GeoRL..30.1291M"><span>Thermal inertia and reversing buoyancy in flow in <span class="hlt">porous</span> media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Menand, Thierry; Raw, Alan; Woods, Andrew W.</p> <p>2003-03-01</p> <p>The displacement of fluids through <span class="hlt">porous</span> <span class="hlt">rocks</span> is fundamental for the recharge of geothermal and hydrocarbon reservoirs [Grant et al., 1982; Lake, 1989], for contaminant dispersal through the groundwater [Bear, 1972] and in controlling mineral reactions in permeable <span class="hlt">rocks</span> [Phillips, 1991]. In many cases, the buoyancy force associated with density differences between the formation fluid and the displacing fluid controls the rate and pattern of flow through the permeable <span class="hlt">rock</span> [Phillips, 1991; Barenblatt, 1996; Turcotte and Schubert, 2002]. Here, using new laboratory experiments, we establish that a striking range of different flow patterns may develop depending on whether this density contrast is associated with differences in temperature and/or composition between the two fluids. Owing to the effects of thermal inertia in a <span class="hlt">porous</span> <span class="hlt">rock</span>, thermal fronts lag behind compositional fronts [Woods and Fitzgerald, 1993; Turcotte and Schubert, 2002], so that two zones of different density develop in the region flooded with injected fluid. This can lead to increasing, decreasing or even reversing buoyancy in the injected liquid; in the latter case it may then form a double-flood front, spreading along both the upper and lower boundary of the <span class="hlt">rock</span>. Recognition of these different flow regimes is key for predicting sweep efficiency and dispersal patterns in natural and engineered flows, and offers new opportunities for the enhanced recovery of natural resources in <span class="hlt">porous</span> <span class="hlt">rocks</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.H21A1324G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.H21A1324G"><span>Percolation and Physical Properties of <span class="hlt">Rock</span> Salt</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ghanbarzadeh, S.; Hesse, M. A.; Prodanovic, M.</p> <p>2015-12-01</p> <p>Textural equilibrium controls the distribution of the liquid phase in many naturally occurring <span class="hlt">porous</span> materials such as partially molten <span class="hlt">rocks</span> and alloys, salt-brine and ice-water systems. In these materials, pore geometry evolves to minimize the solid-liquid interfacial energy while maintaining a constant dihedral angle, θ, at solid-liquid contact lines. A characteristic of texturally equilibrated <span class="hlt">porous</span> media, in the absence of deformation, is that the pore network percolates at any porosity for θ<60° while a percolation threshold exists for θ>60°. However, in ductile polycrystalline materials including <span class="hlt">rock</span> salt, the balance between surface tension and ductile deformation controls the percolation of fluid pockets along grain corners and edges. Here we show sufficiently rapid deformation can overcome this threshold by elongating and connecting isolated pores by examining a large number of accessible salt samples from deep water Gulf of Mexico. We first confirm the percolation threshold in static laboratory experiments on synthetic salt samples with X-ray microtomography. We then provide field evidence on existence of interconnected pore space in <span class="hlt">rock</span> salt in extremely low porosities, significantly below the static percolation threshold. Scaling arguments suggest that strain rates in salt are sufficient to overcome surface tension and may allow percolation. We also present the first level-set computations of three-dimensional texturally equilibrated melt networks in realistic <span class="hlt">rock</span> fabrics. The resulting pore space is used to obtain the effective physical properties of <span class="hlt">rock</span>, effective electrical conductivity and mechanical properties, with a novel numerical model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6965802','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6965802"><span><span class="hlt">Rock</span> mechanics. Second edition</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jumikis, A.R.</p> <p>1983-01-01</p> <p><span class="hlt">Rock</span> Mechanics, 2nd Edition deals with <span class="hlt">rock</span> as an engineering construction material-a material with which, upon which, and within which civil engineers build structures. It thus pertains to hydraulic structures engineering; to highway, railway, canal, foundation, and tunnel engineering; and to all kinds of <span class="hlt">rock</span> earthworks and to substructures in <span class="hlt">rock</span>. Major changes in this new edition include: <span class="hlt">rock</span> classification, <span class="hlt">rock</span> types and description, <span class="hlt">rock</span> testing equipment, <span class="hlt">rock</span> properties, stability effects of discontinuity and gouge, grouting, gunite and shotcrete, and Lugeon's water test. This new edition also covers <span class="hlt">rock</span> bolting and prestressing, pressure-grouted soil anchors, and <span class="hlt">rock</span> slope stabilization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.S41A1822V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.S41A1822V"><span>Determining Pore Pressures Along a Slip Surface Within a Saturated Elastic-Plastic <span class="hlt">Porous</span> Medium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Viesca, R. C.; Rice, J. R.; Dunham, E. M.</p> <p>2008-12-01</p> <p>Here we consider shear rupture along a slip surface in a <span class="hlt">fluid-saturated</span> elastic-plastic <span class="hlt">porous</span> medium, like in landslide and earthquake modeling, and assume that there are different poro-elasto-plastic response properties on the two sides of the slip surface. This different response may be because the fault bordering materials are dissimilar, or just because one side is actively yielding and the other is not, or is yielding but in a different mode. In effect, we are representing a core about a slip surface that divides two similar or contrasting materials. This representation is especially relevant in earthquake rupture dynamics. Studies of mature fault zones have noted a trend of fractured host <span class="hlt">rock</span> extending 10--100m from the fault, with an ultracataclastic core ~100mm about or to one side of the principal slip surface (e.g., Chester and Chester, Tectonophys, 1998; Chester et al., Columbia Univ Pr, 2004). Furthermore, there is likely to exist a material contrast that may come from accumulating km of slip and a bias in accumulated damage. The local pore pressure at the slip surface influences the rupture dynamics because, through the effective stress concept, it controls the local shear strength along the fault, a feature neglected as a simplification in our preliminary poro-elasto-plastic modeling of dynamic rupture (Viesca et al., JGR, 2008). To determine pore pressures at the slip surface under locally elastic-plastic response, we must consider pore pressure discontinuities about that surface that arise in an undrained treatment of off-fault material and their amelioration within resulting thin diffusive boundary layers, such that pore pressure and fluid mass flux in the normal direction are continuous at the slip surface. Our approach builds on previous work considering the effect of contrasts in poroelastic properties on rupture propagation (Rudnicki and Rice, JGR, 2006; Dunham and Rice, JGR, 2008). Here we find expressions for the undrained pore pressure</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5518547','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5518547"><span>Evidence for correlation of ultrasonic attenuation and fluid permeability in very low porosity water-saturated <span class="hlt">rocks</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Berryman, J.G.; Bonner, B.P.; Chin, R.C.Y.</p> <p>1983-07-01</p> <p>The measured amplitude A of ultrasonic pulses in intact and fractured samples of water-saturated gabbro and granite is observed to decrease as the permeability kappa increases according to the proportionality Aproportionalkappa/sup -1/2/. This relation is predicted by Biot's theory of elastic waves in <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> media and, therefore, suggests that Biot's attenuation mechanism may play a significant role in low porosity materials at ultrasonic frequencies. The evidence is not conclusive. The limited data set studied here is also consistent with correlations of the form Aproportionalkappa/sup -Epsilon/ where 0.2<Epsilon<0.6. Nevertheless, the observed correlations may still provide a means for monitoring changes in permeability of low-porosity underground repositories of radioactive waste.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.6201C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.6201C"><span>A new understanding of fluid-<span class="hlt">rock</span> deformation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Crampin, Stuart; Gao, Yuan</p> <p>2015-04-01</p> <p>Cracks in the pavement show that <span class="hlt">rock</span> is weak to shear stress. Consequently we have a conundrum. How does in situ <span class="hlt">rock</span> accumulate the enormous shear-stress energy necessary for release by a large magnitude earthquake without fracturing in smaller earthquakes? For example: observations of changes in seismic shear-wave splitting (SWS) were observed in Iceland before the 2004 Mw9.2 Sumatra-Andaman Earthquake (SAE) at a distance of ~10,500km (the width of the Eurasian Plate) from Indonesia. Observations of SWS monitor microcrack geometry, and the changes in SWS in Iceland indicated that stress-changes before the Sumatra earthquake modified microcrack geometry the width of Eurasia from Indonesia. What is the mechanism for such widespread accumulation of necessarily weak stress? We show that stress is stored in in situ <span class="hlt">rock</span> by the stress-controlled geometry of the <span class="hlt">fluid-saturated</span> stress-aligned microcrack. Microcrack aspect-ratios are aligned by fluid flow or dispersion along pressure-gradients between neighbouring microcracks at different orientations to the stress-field by a mechanism known as Anisotropic Poro-Elasticity or APE. Since the minimum stress is typically horizontal, the microcracks are typically vertically-oriented parallel to the maximum horizontal stress as is confirmed by observations of SWS. Such azimuthally varying shear-wave splitting (SWS) is observed in situ <span class="hlt">rocks</span> in the upper crust, lower crust, and uppermost ~400km of the mantle. (The 'microcracks' in the mantle are intergranular films of hydrolysed melt.) SWS shows that the microcracks are so closely spaced that they verge on fracturing/earthquakes. Phenomena verging on failure are critical-systems with 'butterfly wings' sensitivity. Critical-systems are very common and it must be expected that the Earth, an archetypal complex heterogeneous interactive phenomena is a critical-system. Monitoring SWS above small earthquakes allows stress-accumulation before earthquakes to be recognised and the time</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010066712','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010066712"><span><span class="hlt">Rock</span> Driller</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Peterson, Thomas M.</p> <p>2001-01-01</p> <p>The next series of planetary exploration missions require a method of extracting <span class="hlt">rock</span> and soil core samples. Therefore a prototype ultrasonic core driller (UTCD) was developed to meet the constraints of Small Bodies Exploration and Mars Sample Return Missions. The constraints in the design are size, weight, power, and axial loading. The ultrasonic transducer requires a relatively low axial load, which is one of the reasons this technology was chosen. The ultrasonic generator breadboard section can be contained within the 5x5x3 limits and weighs less than two pounds. Based on results attained the objectives for the first phase were achieved. A number of transducer probes were made and tested. One version only drills, and the other will actually provide a small core from a <span class="hlt">rock</span>. Because of a more efficient transducer/probe, it will run at very low power (less than 5 Watts) and still drill/core. The prototype generator was built to allow for variation of all the performance-effecting elements of the transducer/probe/end effector, i.e., pulse, duty cycle, frequency, etc. The heart of the circuitry is what will be converted to a surface mounted board for the next phase, after all the parameters have been optimized and the microprocessor feedback can be installed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/137555','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/137555"><span>Analytical models for C-14 transport in a partially saturated, fractured, <span class="hlt">porous</span> media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Light, W.B.; Pigford, T.H.; Chambre, P.L.; Lee, W.W.-L.</p> <p>1989-02-01</p> <p>Interaction between fractures and <span class="hlt">rock</span> matrix is considered in developing a criterion for treating fractured <span class="hlt">rock</span> as a <span class="hlt">porous</span> medium for the purpose of transport calculations. The value of a modified Peclet number determines the suitability of the equivalent <span class="hlt">porous</span> medium approach. Using a <span class="hlt">porous</span> medium mode, underground concentrations of {sup 14}CO{sub 2} are predicted for the proposed nuclear waste repository at Yucca Mountain, Nevada. Maximum concentrations near the ground surface are comparable to the USNRC limit for unrestricted areas; travel times are predicted to be hundreds to thousands of years for the assumed parameter values. 8 refs., 7 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010NatCh...2..915H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010NatCh...2..915H"><span><span class="hlt">Porous</span> organic molecules</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Holst, James R.; Trewin, Abbie; Cooper, Andrew I.</p> <p>2010-11-01</p> <p>Most synthetic materials that show molecular-scale porosity consist of one-, two- or three-dimensional networks. <span class="hlt">Porous</span> metal-organic frameworks in particular have attracted a lot of recent attention. By contrast, discrete molecules tend to pack efficiently in the solid state, leaving as little empty space as possible, which leads to non-<span class="hlt">porous</span> materials. This Perspective discusses recent developments with discrete organic molecules that are <span class="hlt">porous</span> in the solid state. Such molecules, which may be either crystalline or amorphous, can be categorized as either intrinsically <span class="hlt">porous</span> (containing permanent covalent cavities) or extrinsically <span class="hlt">porous</span> (inefficiently packed). We focus on the possible advantages of organic molecules over inorganic or hybrid systems in terms of molecular solubility, choice of components and functionalities, and structural mobility and responsiveness in non-covalent extended solids. We also highlight the potential for 'undiscovered' <span class="hlt">porous</span> systems among the large number of cage-like organic molecules that are already known.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/7177178','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7177178"><span>Boiling <span class="hlt">rocks</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Not Available</p> <p>1992-09-01</p> <p>This paper discusses Zeolites, 3-dimensional crystals made up to silicon, aluminum, oxygen, and small amounts of other elements. Highly <span class="hlt">porous</span>, zeolites differ in crystallization and composition. However, both natural and synthetic zeolites, of which in there are about 133, are characterized by submicroscopic channels and holes, often called pores, that let zeolites act as molecular sieves. It is this molecular-sieve capability that has made zeolites so valuable as a catalyst in industrial uses. According to a leading zeolite authority, Dr. John M. Newsam, a director with BIOSYM Technologies, Inc., Every crude oil developer worldwide uses a zeolite as a catalyst. So it's big business. Besides their use in reducing the cost of processing gasoline and other petroleum products, zeolites are helping in cleaning up low-level nuclear wastes and other hazardous materials. They're also used in aromatic processing and in raising pigs and tomatoes. In the coming years, zeolites will used in place of phosphorous in certain products.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5496886','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5496886"><span>Non-Darcian effects in open-ended cavities filled with a <span class="hlt">porous</span> medium</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ettefagh, J.; Vafai, K.; Kim, S.J. )</p> <p>1991-08-01</p> <p>The importance and relevance of non-Darcian associated with the bouyancy driven convection in open-ended cavities filled with <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> medium is analyzed in this work. Several different flow models for <span class="hlt">porous</span> media, such as Brinkman-extended Darcy, Forchheimer-extended Darcy, and generalized flow models, are considered. The significance of inertia and boundary effects, and their crucial influence on the prediction of buouancy-induced flow and heat transfer in open-ended cavities, are investigated. Analysis is made on the proper choice of parameters that can fully determine the criteria for the range of validity of Darcy's law in this type of configuration. Critical values of the inertial parameter, {Lambda}{sub crit}, below which, for any given modified Rayleigh number, the Darcy flow model breaks down, have been investigated. Is is shown that the critical value of the inertial parameter depends on the modified Rayleigh number and that this critical value increases as Ra* increases. It is also observed that for higher modified Rayleigh number, the deviation from a Darcian formulation appears at Darcy numbers greater than 1 {times} 10{sup {minus}4}. The Prandtl number effects on convective flow and heat transfer are shown to be quite significant for small values of Pr. The Prandtl number effects are reduced significantly for higher values of the Prandtl number.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/7235138','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7235138"><span>Convective instability in a <span class="hlt">porous</span> enclosure with a horizontal conducting baffle</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chen, F.; Wang, C.Y. )</p> <p>1993-08-01</p> <p>The study of heat transfer in a <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> medium is essential in a variety of practical situations, including thermal insulation design and geothermal energy utilization. The present paper studies the convective instability in a two-dimensional <span class="hlt">porous</span> enclosure with a horizontal baffle protruding from one of the side walls. The vertical side walls are insulated, while the top and bottom surfaces are maintained at lower and higher constant temperatures, respectively. The present work considers a baffle of high conductivity. We assume the baffle temperature can be considered constant throughout. We ask, for a given enclosure aspect ratio, is the addition of another physical constraint (such as lengthening a baffle) always stabilizing Is there an optimum baffle location and length such that the critical Rayleigh number is maximized In summary, several concluding remarks can be drawn in the following: (1) Other dimensions being same, a centered baffle always results in a more stable state than an off-centered baffle. (2) A full-length baffle, i.e., [beta]/[sigma] = 1, does not necessarily lead to greater stability. Instead, the value of ([beta]/[sigma])[sub max] is usually less than unity. For a centered baffle, the maximum R[sup c] occurs for [beta]/[sigma] [ge] ([beta]/[sigma])[sub max]; while for an off-centered baffle, the maximum R[sup c] occurs at ([beta]/[sigma])[sub max]. (3) The value of ([beta]/[sigma])[sub max] increases with [sigma]. 6 refs., 4 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/334086','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/334086"><span>Radiation effect on natural convection over a vertical cylinder embedded in <span class="hlt">porous</span> media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yih, K.A.</p> <p>1999-02-01</p> <p>Study of buoyancy-induced convection flow and heat transfer in a <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> medium has recently attracted considerable interest because of a number of important energy-related engineering and geophysical applications such as thermal insulation of buildings, geothermal engineering, enhanced recovery of petroleum resources, filtration processes, ground water pollution and sensible heat storage beds. In this paper numerical solutions are presented for the effect of radiation on natural convection about an isothermal vertical cylinder embedded in a saturated <span class="hlt">porous</span> medium. These partial differential equations are transformed into the nonsimilar boundary layer equations which are solved by an implicit finite-difference method (Keller box method). Numerical results for the dimensionless temperature profiles and the local Nusselt number are presented for the transverse curvature parameter {xi}, conduction-radiation parameter R{sub d} and surface temperature excess ratio H. In general, the local Nusselt number increases as the transverse curvature parameter {xi} increases. Furthermore, decreasing the conduction-radiation parameter R{sub d} and increasing surface temperature excess ratio H augments the local heat transfer rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/982836','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/982836"><span>Poroelastic measurement schemes resulting in complete data sets for granular and other anisotropic <span class="hlt">porous</span> media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Berryman, J.G.</p> <p>2009-11-20</p> <p>Poroelastic analysis usually progresses from assumed knowledge of dry or drained <span class="hlt">porous</span> media to the predicted behavior of <span class="hlt">fluid-saturated</span> and undrained <span class="hlt">porous</span> media. Unfortunately, the experimental situation is often incompatible with these assumptions, especially when field data (from hydrological or oil/gas reservoirs) are involved. The present work considers several different experimental scenarios typified by one in which a set of undrained poroelastic (stiffness) constants has been measured using either ultrasound or seismic wave analysis, while some or all of the dry or drained constants are normally unknown. Drained constants for such a poroelastic system can be deduced for isotropic systems from available data if a complete set of undrained compliance data for the principal stresses are available - together with a few other commonly measured quantities such as porosity, fluid bulk modulus, and grain bulk modulus. Similar results are also developed here for anisotropic systems having up to orthotropic symmetry if the system is granular (i.e., composed of solid grains assembled into a solid matrix, either by a cementation process or by applied stress) and the grains are known to be elastically homogeneous. Finally, the analysis is also fully developed for anisotropic systems with nonhomogeneous (more than one mineral type), but still isotropic, grains - as well as for uniform collections of anisotropic grains as long as their axes of symmetry are either perfectly aligned or perfectly random.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DFD.A3007T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DFD.A3007T"><span>Isotherms Around a Heated Horizontal Cylinder Embedded in a <span class="hlt">Porous</span> Medium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Torres Victoria, Áyax Hernando; Sanchez Rosas, Mario; Aragón Rivera, Fernando; Sánchez Cruz, Fausto Alejandro; Medina Ovando, Abraham</p> <p>2014-11-01</p> <p>This work presents an experimental study of free and forced convection phenomena that occur in the vicinity of a heated cylinder embedded in a <span class="hlt">fluid</span> <span class="hlt">saturated</span> <span class="hlt">porous</span> medium. The characteristic distribution of the conformed temperature gradients in the <span class="hlt">porous</span> medium due to pure free convection, and under the action of a continuous and uniform stream were investigated through the use of four different configurations: first by inducing an air stream from below the heated cylinder, second, by placing an air stream on the left hand side of the heat source, third by an air stream acting from the top of the heat source, and fourth by varying the injection angles. The resulting conformation of the buoyant plumes surrounding the heated cylinder when all phenomena reach the steady state were analyzed with an infrared camera. Correspondence is found with the theoretical and numerical solutions proposed by Kurdyumov and Liñán (2000). We wish to thank to the Mexican Petroleum Institute for the unconditional support given to this project. We also thank the Instituto Politécnico Nacional through the SIP Project No. 20141404.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/471114','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/471114"><span>Natural convection heat transfer from a horizontal wavy surface in a <span class="hlt">porous</span> enclosure</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Murthy, P.V.S.N.; Kumar, B.V.R.; Singh, P.</p> <p>1997-02-07</p> <p>The effect of surface undulations on the natural convection heat transfer from an isothermal surface in a Darcian <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> enclosure has been numerically analyzed using the finite element method on a graded nonuniform mesh system. The flow-driving Rayleigh number Ra together with the geometrical parameters of wave amplitude a, wave phase {phi}, and the number of waves N considered in the horizontal dimension of the cavity are found to influence the flow and heat transfer process in the enclosure. For Ra around 50 and above, the phenomenon of flow separation and reattachment is noticed on the walls of the enclosure. A periodic shift in the reattachment point from the bottom wall to the adjacent walls in the clockwise direction, leading to the manifestation of cycles of unicellular and bicellular clockwise and counterclockwise flows, is observed, with the phase varying between 0{degree} and 350{degree}. The counterflow in the secondary circulation zone is intensified with the increase in the value of Ra. The counterflow on the wavy wall hinders the heat transfer into the system. An increase in either wave amplitude or the number of waves considered per unit length decreases the global heat flux into the system. Only marginal changes in global heat flux are noticed with increasing Ra. On the whole, the comparison of global heat flux results in the wavy wall case with those of the horizontal flat wall case shows that, in a <span class="hlt">porous</span> enclosure, the wavy wall reduces the heat transfer into the system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6483367','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6483367"><span>Bacteria transport through <span class="hlt">porous</span> material: Final technical report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yen, T.F.</p> <p>1989-02-13</p> <p>The injection and penetration of bacteria into a reservoir is the most problematic and crucial of the steps in microbial enhanced recovery (MEOR). In the last phase of our work valuable information on bacterial transport in <span class="hlt">porous</span> media was obtained. A great deal of progress was made to determine chemical bonding characteristics between adsorbed bacteria and the <span class="hlt">rock</span> surfaces. In order to further enhance our knowledge of the effects of surface tensions on bacteria transport through <span class="hlt">porous</span> media, a new approach was taken to illustrate the effect of liquid surface tension on bacterial transport through a sandpack column. Work in surface charge characterization of reservoir <span class="hlt">rock</span> as a composite oxide system was also accomplished. In the last section of this report a mathematical model to simulate the simultaneous diffusion and growth of bacteria cells in a nutrient-enriched <span class="hlt">porous</span> media is proposed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17747570','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17747570"><span><span class="hlt">Rock</span> Degradation by Alkali Metals: A Possible Lunar Erosion Mechanism.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Naughton, J J; Barnes, I L; Hammond, D A</p> <p>1965-08-06</p> <p>When <span class="hlt">rocks</span> melt under ultrahigh-vacuum conditions, their alkali components volatilize as metals. These metal vapors act to comminute polycrystalline <span class="hlt">rocks</span> to their component minerals. The resultant powder is <span class="hlt">porous</span> and loosely packed and its characteristics may be compatible with the lunar surface as revealed by the Ranger photographs. If meteorite impact or lunar volcanism has produced vaporization or areas of molten lava, alkali erosion may have given dust of this character in adjacent solid areas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.H54D..03P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.H54D..03P"><span>Capillary pressure and heterogeneity for the CO2/water system in sandstone <span class="hlt">rocks</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pini, R.; Krevor, S. C.; Benson, S. M.</p> <p>2011-12-01</p> <p> sandstones <span class="hlt">rock</span> cores with different lithology and grain sorting. Experiments are carried out at 25 and 50C and at 9 MPa pore pressure, while keeping the confining pressure on the core at 12 MPa. The effect of temperature on the capillary pressure is consistent with observed changes in fluid properties, such as the interfacial tension. Moreover, data are compared to MICP results, thus allowing to gain additional insights with respect to the wetting and interfacial properties of the CO2/water system. During a core-flooding experiment, X-ray Computed Tomography (CT) scanning allows for precise imaging of <span class="hlt">fluid</span> <span class="hlt">saturations</span> at a resolution of about 1mm3. It is shown that a distribution of capillary pressure curves can be associated to the observed distribution of CO2 saturation within the core, allowing for the quantification of heterogeneity at the sub-core scale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://aapgbull.geoscienceworld.org/content/67/2/191.abstract','USGSPUBS'); return false;" href="http://aapgbull.geoscienceworld.org/content/67/2/191.abstract"><span>High=porosity Cenozoic carbonate <span class="hlt">rocks</span> of South Florida: progressive loss of porosity with depth</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Halley, Robert B.; Schmoker, James W.</p> <p>1983-01-01</p> <p>Porosity measurements by borehole gravity meter in subsurface Cenozoic carbonates of South Florida reveal an extremely <span class="hlt">porous</span> mass of limestone and dolomite which is transitional in total pore volume between typical porosity values for modern carbonate sediments and ancient carbonate <span class="hlt">rocks</span>. A persistent decrease of porosity with depth, similar to that of chalks of the Gulf Coast, occurs in these <span class="hlt">rocks</span>. Carbonate strata with less than 20% porosity are absent from the <span class="hlt">rocks</span> studied here. Aquifers and aquicludes cannot be distinguished on the basis of porosity. Aquifers are not exceptionally <span class="hlt">porous</span> when compared to other Tertiary carbonate <span class="hlt">rocks</span> in South Florida. Permeability in these strata is governed more by the spacial distribution of pore space and matrix than by total volume of porosity present. Dolomite is as <span class="hlt">porous</span> as, or slightly less <span class="hlt">porous</span> than, limestones in these <span class="hlt">rocks</span>. This observation places limits on any model proposed for dolomitization and suggests that dolomitization does not take place by a simple ion-for-ion replacement of magnesium for calcium. Dolomitization may be selective for less <span class="hlt">porous</span> limestone, or it may involve the incorporation of significant amounts of carbonate as well as magnesium into the <span class="hlt">rock</span>. The great volume of pore space in these <span class="hlt">rocks</span> serves to highlight the inefficiency of early diagenesis in reducing carbonate porosity and to emphasize the importance of later porosity reduction which occurs during the burial or late near-surface history of limestones and dolomites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70009824','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70009824"><span>Thermal conductivity of carbonate <span class="hlt">rocks</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Thomas, J.; Frost, R.R.; Harvey, R.D.</p> <p>1973-01-01</p> <p>The thermal conductivities of several well-defined carbonate <span class="hlt">rocks</span> were determined near 40??C. Values range from 1.2 W m-1 C-1 for a highly <span class="hlt">porous</span> chalk to 5.1 W m-1 C-1 for a dolomite. The thermal conductivity of magnesite (5.0) is at the high end of the range, and that for Iceland Spar Calcite (3.2) is near the middle. The values for limestones decrease linearly with increasing porosity. Dolomites of comparable porosity have greater thermal conductivities than limestones. Water-sorbed samples have expected greater thermal conductivities than air-saturated (dry) samples of the same <span class="hlt">rock</span>. An anomalously large increase in the thermal conductivity of a water-sorbed clayey dolomite over that of the same sample when dry is attributed to the clay fraction, which swells during water inhibition, causing more solid-to-solid contacts within the dolomite framework. Measurements were made with a Colora Thermoconductometer. Chemical and mineralogical analyses were made and tabulated. Porosity of the <span class="hlt">rocks</span> was determined by mercury porosimetry and also from density measurements. The Iceland Spar Calcite and magnesite were included for reference. ?? 1973.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=encyclopedic&pg=3&id=EJ244605','ERIC'); return false;" href="https://eric.ed.gov/?q=encyclopedic&pg=3&id=EJ244605"><span>A <span class="hlt">Rock</span> Encyclopedia That Includes <span class="hlt">Rock</span> Samples.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Laznicka, Peter</p> <p>1981-01-01</p> <p>Described is a <span class="hlt">rock</span> encyclopedia combining <span class="hlt">rock</span> sample sets and encyclopedic word and picture entries which can be used as a realistic information resource for independent study or as a part of a course. (JT)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22054192','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22054192"><span>X-ray scattering by <span class="hlt">porous</span> silicon modulated structures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lomov, A. A.; Punegov, V. I.; Karavanskii, V. A.; Vasil'ev, A. L.</p> <p>2012-03-15</p> <p>A multilayered <span class="hlt">porous</span> structure formed as a result of the anodization of a Si(111)(Sb) substrate in an HF:C{sub 2}H{sub 5}OH (1: 2) solution with a periodically alternating current has been investigated by high-resolution X-ray diffraction. It is established that, despite 50% porosity, a thickness of 30 {mu}m, and significant strain (4 Multiplication-Sign 10{sup -3)}, the <span class="hlt">porous</span> silicon structure consists mainly of coherent crystallites. A model of coherent scattering from a multilayered periodic <span class="hlt">porous</span> structure is proposed within the dynamic theory of diffraction. It is shown that the presence of gradient strains of 5 Multiplication-Sign 10{sup -4} or higher leads to phase loss upon scattering from <span class="hlt">porous</span> superlattices and the suppression of characteristic satellites in <span class="hlt">rocking</span> curves.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=MSFC-6903957&hterms=clippers&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dclippers','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=MSFC-6903957&hterms=clippers&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dclippers"><span>Lunar <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1969-01-01</p> <p>The second manned lunar landing mission, Apollo 12 launched from launch pad 39-A at Kennedy Space Center in Florida on November 14, 1969 via a Saturn V launch vehicle. The Saturn V vehicle was developed by the Marshall Space Flight Center (MSFC) under the direction of Dr. Wernher von Braun. Aboard Apollo 12 was a crew of three astronauts: Alan L. Bean, pilot of the Lunar Module (LM), Intrepid; Richard Gordon, pilot of the Command Module (CM), Yankee Clipper; and Spacecraft Commander Charles Conrad. The LM, Intrepid, landed astronauts Conrad and Bean on the lunar surface in what's known as the Ocean of Storms while astronaut Richard Gordon piloted the CM, Yankee Clipper, in a parking orbit around the Moon. Lunar soil activities included the deployment of the Apollo Lunar Surface Experiments Package (ALSEP), finding the unmanned Surveyor 3 that landed on the Moon on April 19, 1967, and collecting 75 pounds (34 kilograms) of <span class="hlt">rock</span> samples, some of which can be seen in this photograph. Apollo 12 safely returned to Earth on November 24, 1969.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/869166','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/869166"><span>Ventilation of <span class="hlt">porous</span> media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Neeper, Donald A.</p> <p>1994-01-01</p> <p>Methods for distributing gases throughout the interstices of <span class="hlt">porous</span> materials and removing volatile substances from the interstices of <span class="hlt">porous</span> materials. Continuous oscillation of pressures and flows results in increased penetration of the interstices by flowing gases and increased transport of gaseous components out of the interstices. The invention is particularly useful in soil vapor extraction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5177290','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/5177290"><span>Ventilation of <span class="hlt">porous</span> media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Neeper, D.A.</p> <p>1994-02-22</p> <p>Methods are presented for distributing gases throughout the interstices of <span class="hlt">porous</span> materials and removing volatile substances from the interstices of <span class="hlt">porous</span> materials. Continuous oscillation of pressures and flows results in increased penetration of the interstices by flowing gases and increased transport of gaseous components out of the interstices. The invention is particularly useful in soil vapor extraction. 10 figures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1257114','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1257114"><span>Hierarchical <span class="hlt">Porous</span> Structures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Grote, Christopher John</p> <p>2016-06-07</p> <p>Materials Design is often at the forefront of technological innovation. While there has always been a push to generate increasingly low density materials, such as aero or hydrogels, more recently the idea of bicontinuous structures has gone more into play. This review will cover some of the methods and applications for generating both <span class="hlt">porous</span>, and hierarchically <span class="hlt">porous</span> structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGE....11d5015F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGE....11d5015F"><span>S-wave velocity self-adaptive prediction based on a variable dry <span class="hlt">rock</span> frame equivalent model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Feng-Ying, Yang; Xing-Yao, Yin; Bo, Liu</p> <p>2014-08-01</p> <p>Seismic velocities are important reservoir parameters in seismic exploration. The Gassmann theory has been widely used to predict velocities of <span class="hlt">fluid-saturated</span> isotropic reservoirs at low frequency. According to Gassmann theory, dry <span class="hlt">rock</span> frame moduli are essential input parameters for estimating reservoir velocities. A variable dry <span class="hlt">rock</span> frame equivalent model called VDEM based on the differential effective medium (DEM) theory is constructed in this paper to obtain the dry <span class="hlt">rock</span> frame moduli. We decouple the DEM equations by introducing variable parameters, then simplify these decoupled equations to get the equivalent dry <span class="hlt">rock</span> fame model. The predicted dry <span class="hlt">rock</span> frame moduli by the VDEM are in good agreement with the laboratory data. The VDEM is also utilized to predict S-wave velocity combined with Gassmann theory. A self-adaptive inversion method is applied to fit the variable parameters with the constraint of P-wave velocity from well logging data. The S-wave velocity is estimated from these inversed parameters. A comparison between the self-adaptive method and the Xu-White model on S-wave velocity estimation is made. The results corroborate that the self-adaptive method is flexible and effective for S-wave velocity prediction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002Tectp.350...17R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002Tectp.350...17R"><span>Mass transfer controlled by fracturing in micritic carbonate <span class="hlt">rocks</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Richard, James; Coulon, Michel; Gaviglio, Patrick</p> <p>2002-05-01</p> <p>The fractured Coniacian chalk from the Omey area (Paris Basin, France) displays strong evidence of modifications controlled by brittle deformation. Fracturing is associated with important changes in pore space (decrease in total porosity and pore interconnection, change in distribution of pore access diameters and capillary characteristics), nannofacies (gradual evolution from a point-contact fabric to a welded, interlocked or coalescent fabric) and chemical composition (Sr concentration decrease). These modifications result from fluid-<span class="hlt">rock</span> interaction that control significant mass transfer (percentage of secondary calcite >50%). Sr is a remarkable indicator of these mass transfers. Sr analyses allowed us to prove that the deformed zone (26.7 m) is wider than the fractured zone (11.3 m). They also indicate that the footwall block is less affected than the hanging wall block. A physicochemical model of the deformation mechanism is proposed. It shows that a cyclic process of fracturing controls the temporal evolution of the <span class="hlt">fluid</span> <span class="hlt">saturation</span> and fluid pressure and, consequently, the mass transfer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/415139','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/415139"><span><span class="hlt">Porous</span> silicon gettering</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tsuo, Y.S.; Menna, P.; Al-Jassim, M.</p> <p>1995-08-01</p> <p>We have studied a novel extrinsic gettering method that utilizes the very large surface areas, produced by <span class="hlt">porous</span> silicon etch on both front and back surfaces of the silicon wafer, as gettering sites. In this method, a simple and low-cost chemical etching is used to generate the <span class="hlt">porous</span> silicon layers. Then, a high-flux solar furnace (HFSF) is used to provide high-temperature annealing and the required injection of silicon interstitials. The gettering sites, along with the gettered impurities, can be easily removed at the end the process. The <span class="hlt">porous</span> silicon removal process consists of oxidizing the <span class="hlt">porous</span> silicon near the end the gettering process followed by sample immersion in HF acid. Each <span class="hlt">porous</span> silicon gettering process removes up to about 10 {mu}m of wafer thickness. This gettering process can be repeated so that the desired purity level is obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20840339','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20840339"><span>Uncertainty quantification for <span class="hlt">porous</span> media flows</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Christie, Mike . E-mail: mike.christie@pet.hw.ac.uk; Demyanov, Vasily; Erbas, Demet</p> <p>2006-09-01</p> <p>Uncertainty quantification is an increasingly important aspect of many areas of computational science, where the challenge is to make reliable predictions about the performance of complex physical systems in the absence of complete or reliable data. Predicting flows of oil and water through oil reservoirs is an example of a complex system where accuracy in prediction is needed primarily for financial reasons. Simulation of fluid flow in oil reservoirs is usually carried out using large commercially written finite difference simulators solving conservation equations describing the multi-phase flow through the <span class="hlt">porous</span> reservoir <span class="hlt">rocks</span>. This paper examines a Bayesian Framework for uncertainty quantification in <span class="hlt">porous</span> media flows that uses a stochastic sampling algorithm to generate models that match observed data. Machine learning algorithms are used to speed up the identification of regions in parameter space where good matches to observed data can be found.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JTAM...47c..25E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JTAM...47c..25E"><span>Heat and Mass Transfer of Unsteady Hydromagnetic Free Convection Flow Through <span class="hlt">Porous</span> Medium Past a Vertical Plate with Uniform Surface Heat Flux</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>El-Aziz, Mohamed Abd; Yahya, Aishah S.</p> <p>2017-09-01</p> <p>Simultaneous effects of thermal and concentration diffusions in unsteady magnetohydrodynamic free convection flow past a moving plate maintained at constant heat flux and embedded in a viscous <span class="hlt">fluid</span> <span class="hlt">saturated</span> <span class="hlt">porous</span> medium is presented. The transport model employed includes the effects of thermal radiation, heat sink, Soret and chemical reaction. The fluid is considered as a gray absorbing-emitting but non-scattering medium and the Rosseland approximation in the energy equations is used to describe the radiative heat flux for optically thick fluid. The dimensionless coupled linear partial differential equations are solved by using Laplace transform technique. Numerical results for the velocity, temperature, concentration as well as the skin friction coefficient and the rates of heat and mass transfer are shown graphically for different values of physical parameters involved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24077359','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24077359"><span>Impact of fluid-<span class="hlt">rock</span> chemical interactions on tracer transport in fractured <span class="hlt">rocks</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mukhopadhyay, Sumit; Liu, H-H; Spycher, N; Kennedy, B M</p> <p>2013-11-01</p> <p>In this paper, we investigate the impact of chemical interactions, in the form of mineral precipitation and dissolution reactions, on tracer transport in fractured <span class="hlt">rocks</span>. When a tracer is introduced in fractured <span class="hlt">rocks</span>, it moves through the fracture primarily by advection and it also enters the stagnant water of the surrounding <span class="hlt">rock</span> matrix through diffusion. Inside the <span class="hlt">porous</span> <span class="hlt">rock</span> matrix, the tracer chemically interacts with the solid materials of the <span class="hlt">rock</span>, where it can precipitate depending on the local equilibrium conditions. Alternatively, it can be dissolved from the solid phase of the <span class="hlt">rock</span> matrix into the matrix pore water, diffuse into the flowing fluids of the fracture and is advected out of it. We show that such chemical interactions between the fluid and solid phases have significant impact on tracer transport in fractured <span class="hlt">rocks</span>. We invoke the dual-porosity conceptualization to represent the fractured <span class="hlt">rocks</span> and develop a semi-analytical solution to describe the transient transport of tracers in interacting fluid-<span class="hlt">rock</span> systems. To test the accuracy and stability of the semi-analytical solution, we compare it with simulation results obtained with the TOUGHREACT simulator. We observe that, in a chemically interacting system, the tracer breakthrough curve exhibits a pseudo-steady state, where the tracer concentration remains more or less constant over a finite period of time. Such a pseudo-steady condition is not observed in a non-reactive fluid-<span class="hlt">rock</span> system. We show that the duration of the pseudo-state depends on the physical and chemical parameters of the system, and can be exploited to extract information about the fractured <span class="hlt">rock</span> system, such as the fracture spacing and fracture-matrix interface area. © 2013.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.H43L..01K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.H43L..01K"><span><span class="hlt">Rock</span> Physics: Getting What We Want From What We Measure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Knight, R. J.</p> <p>2016-12-01</p> <p><span class="hlt">Rock</span> physics is the field of study that determines, through laboratory and field observations, and through numerical and theoretical modeling, the relationship between the geophysical parameters that we measure (e.g., electrical resistivity, dielectric constant, elastic wave velocities) and the material properties that we want (e.g., porosity, lithology, <span class="hlt">fluid</span> <span class="hlt">saturation</span>, hydraulic conductivity). Over the past 30 years there has been increasing use of geophysical methods for characterizing hydrogeologic systems, and the emergence of the field of hydrogeophysics. The historical path of <span class="hlt">rock</span> physics in hydrogeophysics, as in all fields of study, has been one of introducing increasing complexity into the way we consider, and model, the geophysical response of multicomponent systems. There has been a progression from incorporating information about volume fractions and then geometries of components, to incorporating information about interfaces and interactions between components. The multicomponent systems that we study range from small-scale (centimeters) samples where measurements are made directly in the laboratory, to large-scale (meters to tens of meters) field samples probed remotely using surface-based and airborne geophysical methods. The components, geometries, interfaces and interactions that must be incorporated into our <span class="hlt">rock</span> physics relationships change in scale; and the physics needs to be upscaled accordingly. Laboratory experiments still provide the starting point for observing and understanding the key mechanisms linking the geophysical measurement to the material properties. But numerical experiments, with digital <span class="hlt">rocks</span>, can now allow us to explore a range of sample conditions and types not previously feasible. Integration with other forms of data and data acquisition at well-characterized sites are starting to provide what we really need to interpret our geophysical measurements of hydrogeologic systems: the up-scaled <span class="hlt">rock</span> physics relationships that</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.4282A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.4282A"><span>Barometric pumping of a fractured <span class="hlt">porous</span> medium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Adler, Pierre; Varloteaux, Clément; Mourzenko, Valeri; François Thovert, Jean; Guillon, Sophie; Pili, Eric</p> <p>2014-05-01</p> <p>Fluctuations in the ambient atmospheric pressure result in motion of air in <span class="hlt">porous</span> and fractured media. This mechanism, known as barometric (or atmospheric) pumping, efficiently transports gaseous species through the vadose zone to the atmosphere. This is of interest in many environmental and engineering fields, such as transport of trace gases from soil to atmosphere, environmental remediation of contaminated sites, radon in buildings and last but not least detection of nuclear explosions or leakage from carbon sequestration sites. The physical situation has been addressed in the following way. The fractures are modeled as polygonal plane surfaces with a given transmissivity embedded in a <span class="hlt">porous</span> medium with a given permeability. The fluid is slightly compressible and is assumed to obey Darcy's law in the fractures and the <span class="hlt">porous</span> medium with exchanges between them. The solute obeys convection-diffusion equations in both media again with exchanges between them. The fractures and the <span class="hlt">porous</span> medium located in between them are meshed by triangles and tetrahedra. The equations are discretized by the finite volume method. In order to improve numerical precision, a Flux Limiting Scheme is applied to the transport equations ; moreover, special care is devoted to the description of the solute transfer between the fractures and the <span class="hlt">porous</span> medium. The resulting equations are solved by conjugate gradient algorithms. This model is applied to the Roselend Natural Laboratory. At a 55 m depth, a sealed cavity allows for gas release experiments across fractured <span class="hlt">porous</span> <span class="hlt">rocks</span> in the unsaturated zone. The fractures are hexagons with a radius of 5m; their density is larger than 2.4 10-3 m-3; the aperture is of the order of 0.5 mm. The pressure fluctuations are sinusoidal, of amplitude 0.01 bar and period 1 week. The solute concentration is supposed to be equal to 1 at the bottom of the site. Systematic results will be presented. First, the precision of the calculations is assessed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/889216','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/889216"><span>Characterization of <span class="hlt">rock</span> for constraining reservoir scale tomography at the Geysers geothermal field</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Boitnott, G.N.; Bonner, B.P.</p> <p>1994-01-20</p> <p>A suite of laboratory measurements are being conducted on Geysers graywacke recovered from a drilled depth of 2599 meters in NEGU-17. The tests are being conducted to characterize the effect of pressure and <span class="hlt">fluid</span> <span class="hlt">saturation</span> on the seismic properties of the graywacke matrix. The measurements indicate that the graywacke is an unusual <span class="hlt">rock</span> in many respects. Both compressional and shear velocities exhibit relatively little change with pressure. Water saturation causes a slight increase in the compressional velocity, quantitatively consistent with predictions from the Biot-Gassmann equations. Shear velocity decreases with water saturation by an amount greater than that predicted by the Biot-Gassmann equations. This decrease is attributed to chemomechanical weakening caused by the presence of water. Measurements of Q, from torsion experiments on room dry samples at seismic frequencies indicate unusually high Q, (~500). Water saturation decreases the shear modulus by 12 percent, again indicative of chemomechanical weakening. Q, is lower for the water saturated condition, but still relatively high for <span class="hlt">rock</span> at low stress. Results of ultrasonic pulse propagation experiments on partially saturated samples are typical of low porosity <span class="hlt">rocks</span>, being characterized by a monotonic decrease in compressional and shear velocity with decrease in saturation. An increase in shear velocity and low frequency shear modulus after vacuum drying indicates the presence of chemo-mechanical weakening resulting from the presence of small amounts of water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22264795','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22264795"><span>X-ray microtomography application in pore space reservoir <span class="hlt">rock</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Oliveira, M F S; Lima, I; Borghi, L; Lopes, R T</p> <p>2012-07-01</p> <p>Characterization of porosity in carbonate <span class="hlt">rocks</span> is important in the oil and gas industry since a major hydrocarbons field is formed by this lithology and they have a complex media <span class="hlt">porous</span>. In this context, this research presents a study of the pore space in limestones <span class="hlt">rocks</span> by x-ray microtomography. Total porosity, type of porosity and pore size distribution were evaluated from 3D high resolution images. Results show that carbonate <span class="hlt">rocks</span> has a complex pore space system with different pores types at the same facies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=245542','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=245542"><span>Geometric and Hydrodynamic Characteristics of Three-dimensional Saturated Prefractal <span class="hlt">Porous</span> Media Determined with Lattice Boltzmann Modeling</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Fractal and prefractal geometric models have substantial potential of contributing to the analysis of flow and transport in <span class="hlt">porous</span> media such as soils and reservoir <span class="hlt">rocks</span>. In this study, geometric and hydrodynamic parameters of saturated 3D mass and pore-solid prefractal <span class="hlt">porous</span> media were characteri...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMNS33B..02M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMNS33B..02M"><span>A <span class="hlt">Rock</span> Physics Based Seismic Interpretation for a Deltaic Shaly Sand Reservoir from Surface Seismic and Wireline Log Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Morshed, S. M.; Ullah, A. S.; Jahan, I.; Rahman, M. M.</p> <p>2013-12-01</p> <p>We present an integrated quantitative seismic interpretation method based on conventional wireline log data and 2D surface seismic data for a deltaic shaly sand reservoir where frequent shaling out of the sand-shale laminated sequence resulted in dry holes in some previous drilling cases. Nineteen 2D post-stack seismic sections tied with seven well controls from the Rashidpur gas field of Bangladesh were used in this study. The study comprises petrophysical analysis from the conventional geophysical well logs (i.e. gamma ray, density, neutron and resistivity logs) to quantitative seismic interpretation using sonic log and 2D seismic data. The petrophysical analysis contributed sand/shale ratio, porosity and <span class="hlt">fluid</span> <span class="hlt">saturation</span> at a well location. A major portion of the work was focused on a <span class="hlt">rock</span> physics analysis for linking interpreted petrophysical data with sonic observations. A set of seismic velocity profiles were established using varied P-wave velocities obtained from Hashin-Strikman-Walpole data fitting method for varying reservoir parameters such as porosity, clay content, pore fluid and <span class="hlt">fluid</span> <span class="hlt">saturation</span>. We found that each of the reservoir parameters has a strong control on elastic properties (i.e. seismic velocities) of the <span class="hlt">rock</span>, for example a 10 percent increase in porosity causes an 8% drop of P-wave velocity. Seismic amplitudes on 19 seismic sections were picked aided by the synthetic seismograms generated from the established velocity profiles. The resulting isopach, sand/shale ratio, porosity and <span class="hlt">fluid</span> <span class="hlt">saturation</span> map shows improved scenarios of reservoir structure and stratigraphy as well as better reservoir characterization. P-wave velocities (Vp) are plotted as a function of porosities. The observed sonic data are color coded by clay content values. The Hashin-Strikman-Walpole upper and lower bounding lines are plotted for a two phase composite of matrix and fluid (brine).The matrix phase contains 60,70, 80 and 90 percents of quartz with clay mixture</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040088791&hterms=nmr&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dnmr','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040088791&hterms=nmr&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dnmr"><span>Probing <span class="hlt">porous</span> media with gas diffusion NMR</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mair, R. W.; Wong, G. P.; Hoffmann, D.; Hurlimann, M. D.; Patz, S.; Schwartz, L. M.; Walsworth, R. L.</p> <p>1999-01-01</p> <p>We show that gas diffusion nuclear magnetic resonance (GD-NMR) provides a powerful technique for probing the structure of <span class="hlt">porous</span> media. In random packs of glass beads, using both laser-polarized and thermally polarized xenon gas, we find that GD-NMR can accurately measure the pore space surface-area-to-volume ratio, S/V rho, and the tortuosity, alpha (the latter quantity being directly related to the system's transport properties). We also show that GD-NMR provides a good measure of the tortuosity of sandstone and complex carbonate <span class="hlt">rocks</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoJI.209.1352V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoJI.209.1352V"><span>Theoretical predicting of permeability evolution in damaged <span class="hlt">rock</span> under compressive stress</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vu, M. N.; Nguyen, S. T.; To, Q. D.; Dao, N. H.</p> <p>2017-05-01</p> <p>This paper outlines an analytical model of crack growth induced permeability changes. A theoretical solution of effective permeability of cracked <span class="hlt">porous</span> media is derived. The fluid flow obeys Poisseuille's law along the crack and Darcy's law in the <span class="hlt">porous</span> matrix. This solution exhibits a percolation threshold for any type of crack distribution apart from a parallel crack distribution. The physical behaviour of fluid flow through a cracked <span class="hlt">porous</span> material is well reproduced by the proposed model. The presence of this effective permeability coupling to analytical expression of crack growth under compression enables the modelling of the permeability variation due to stress-induced cracking in a <span class="hlt">porous</span> <span class="hlt">rock</span>. This incorporation allows the prediction of the permeability change of a <span class="hlt">porous</span> <span class="hlt">rock</span> embedding an anisotropic crack distribution from any initial crack density, that is, lower, around or upper to percolation threshold. The interaction between cracks is not explicitly taken into account. The model is well applicable both to micro- and macrocracks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoJI.tmp...91V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoJI.tmp...91V"><span>Theoretical predicting of permeability evolution in damaged <span class="hlt">rock</span> under compressive stress</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vu, M. N.; Nguyen, S. T.; To, Q. D.; Dao, N. H.</p> <p>2017-03-01</p> <p>This paper outlines an analytical model of crack growth induced permeability changes. A theoretical solution of effective permeability of cracked <span class="hlt">porous</span> media is derived. The fluid flow obeys Poisseuille's law along the crack and Darcy's law in the <span class="hlt">porous</span> matrix. This solution exhibits a percolation threshold for any type of crack distribution apart from a parallel crack distribution. The physical behaviour of fluid flow through a cracked <span class="hlt">porous</span> material is well reproduced by the proposed model. The presence of this effective permeability coupling to analytical expression of crack growth under compression enables the modelling of the permeability variation due to stress-induced cracking in a <span class="hlt">porous</span> <span class="hlt">rock</span>. This incorporation allows the prediction of the permeability change of a <span class="hlt">porous</span> <span class="hlt">rock</span> embedding an anisotropic crack distribution from any initial crack density, i.e. lower, around or upper to percolation threshold. The interaction between cracks is not explicitly taken into account. The model is well applicable both to micro and macro-cracks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1064437','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1064437"><span>Preparation of asymmetric <span class="hlt">porous</span> materials</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Coker, Eric N [Albuquerque, NM</p> <p>2012-08-07</p> <p>A method for preparing an asymmetric <span class="hlt">porous</span> material by depositing a <span class="hlt">porous</span> material film on a flexible substrate, and applying an anisotropic stress to the <span class="hlt">porous</span> media on the flexible substrate, where the anisotropic stress results from a stress such as an applied mechanical force, a thermal gradient, and an applied voltage, to form an asymmetric <span class="hlt">porous</span> material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090040067','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090040067"><span>Rollerjaw <span class="hlt">Rock</span> Crusher</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Peters, Gregory; Brown, Kyle; Fuerstenau, Stephen</p> <p>2009-01-01</p> <p>The rollerjaw <span class="hlt">rock</span> crusher melds the concepts of jaw crushing and roll crushing long employed in the mining and <span class="hlt">rock</span>-crushing industries. Rollerjaw <span class="hlt">rock</span> crushers have been proposed for inclusion in geological exploration missions on Mars, where they would be used to pulverize <span class="hlt">rock</span> samples into powders in the tens of micrometer particle size range required for analysis by scientific instruments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080004797','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080004797"><span>Fabricating <span class="hlt">porous</span> silicon carbide</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shor, Joseph S. (Inventor); Kurtz, Anthony D. (Inventor)</p> <p>1994-01-01</p> <p>The formation of <span class="hlt">porous</span> SiC occurs under electrochemical anodization. A sample of SiC is contacted electrically with nickel and placed into an electrochemical cell which cell includes a counter electrode and a reference electrode. The sample is encapsulated so that only a bare semiconductor surface is exposed. The electrochemical cell is filled with an HF electrolyte which dissolves the SiC electrochemically. A potential is applied to the semiconductor and UV light illuminates the surface of the semiconductor. By controlling the light intensity, the potential and the doping level, a <span class="hlt">porous</span> layer is formed in the semiconductor and thus one produces <span class="hlt">porous</span> SiC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA047209','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA047209"><span>Accelerated Weathering of <span class="hlt">Rocks</span>.</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1977-08-01</p> <p>Dry tests en polished specimens with alternating heating and co- oling actions; ii) Wet tests in destilled water, with alternating...<span class="hlt">Rock</span>-type Dry tests KxlO2 Wet tests KxlO2 Sound <span class="hlt">rock</span> SR 3.64 8.31 Medium altered <span class="hlt">rock</span> MAR 4.96 31.58 Very altered <span class="hlt">rock</span> VAR 8.89 116.20 TABLE X...Sound <span class="hlt">rock</span> SR Medium altered <span class="hlt">rock</span> Very altered <span class="hlt">rock</span>" KAR VAR ’ Reflectivity R (%) dry test wet test dry test wet test dry test wet</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JHyd..553..637L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JHyd..553..637L"><span>Probing the water distribution in <span class="hlt">porous</span> model sands with two immiscible fluids: A nuclear magnetic resonance micro-imaging study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Bum Han; Lee, Sung Keun</p> <p>2017-10-01</p> <p>The effect of the structural heterogeneity of <span class="hlt">porous</span> networks on the water distribution in <span class="hlt">porous</span> media, initially saturated with immiscible fluid followed by increasing durations of water injection, remains one of the important problems in hydrology. The relationship among convergence rates (i.e., the rate of <span class="hlt">fluid</span> <span class="hlt">saturation</span> with varying injection time) and the macroscopic properties and structural parameters of <span class="hlt">porous</span> media have been anticipated. Here, we used nuclear magnetic resonance (NMR) micro-imaging to obtain images (down to ∼50 μm resolution) of the distribution of water injected for varying durations into <span class="hlt">porous</span> networks that were initially saturated with silicone oil. We then established the relationships among the convergence rates, structural parameters, and transport properties of <span class="hlt">porous</span> networks. The volume fraction of the water phase increases as the water injection duration increases. The 3D images of the water distributions for silica gel samples are similar to those of the glass bead samples. The changes in water saturation (and the accompanying removal of silicone oil) and the variations in the volume fraction, specific surface area, and cube-counting fractal dimension of the water phase fit well with the single-exponential recovery function { f (t) = a [ 1 -exp (- λt) ] } . The asymptotic values (a, i.e., saturated value) of the properties of the volume fraction, specific surface area, and cube-counting fractal dimension of the glass bead samples were greater than those for the silica gel samples primarily because of the intrinsic differences in the <span class="hlt">porous</span> networks and local distribution of the pore size and connectivity. The convergence rates of all of the properties are inversely proportional to the entropy length and permeability. Despite limitations of the current study, such as insufficient resolution and uncertainty for the estimated parameters due to sparsely selected short injection times, the observed trends highlight the first</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/145809','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/145809"><span>MAGNUM2D. Radionuclide Transport <span class="hlt">Porous</span> Media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Langford, D.W.; Baca, R.G.</p> <p>1989-03-01</p> <p>MAGNUM2D was developed to analyze thermally driven fluid motion in the deep basalts below the Paco Basin at the Westinghouse Hanford Site. Has been used in the Basalt Waste Isolation Project to simulate nonisothermal groundwater flow in a heterogeneous anisotropic medium and heat transport in a water/<span class="hlt">rock</span> system near a high level nuclear waste repository. Allows three representations of the hydrogeologic system: an equivalent <span class="hlt">porous</span> continuum, a system of discrete, unfilled, and interconnecting fractures separated by impervious <span class="hlt">rock</span> mass, and a low permeability <span class="hlt">porous</span> continuum with several discrete, unfilled fractures traversing the medium. The calculations assume local thermodynamic equilibrium between the <span class="hlt">rock</span> and groundwater, nonisothermal Darcian flow in the continuum portions of the <span class="hlt">rock</span>, and nonisothermal Poiseuille flow in discrete unfilled fractures. In addition, the code accounts for thermal loading within the elements, zero normal gradient and fixed boundary conditions for both temperature and hydraulic head, and simulation of the temperature and flow independently. The Q2DGEOM preprocessor was developed to generate, modify, plot and verify quadratic two dimensional finite element geometries. The BCGEN preprocessor generates the boundary conditions for head and temperature and ICGEN generates the initial conditions. The GRIDDER postprocessor interpolates nonregularly spaced nodal flow and temperature data onto a regular rectangular grid. CONTOUR plots and labels contour lines for a function of two variables and PARAM plots cross sections and time histories for a function of time and one or two spatial variables. NPRINT generates data tables that display the data along horizontal or vertical cross sections. VELPLT differentiates the hydraulic head and buoyancy data and plots the velocity vectors. The PATH postprocessor plots flow paths and computes the corresponding travel times.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/139356','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/139356"><span>MAGNUM2D. Radionuclide Transport <span class="hlt">Porous</span> Media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Langford, D.W.; Baca, R.G.</p> <p>1988-08-01</p> <p>MAGNUM2D was developed to analyze thermally driven fluid motion in the deep basalts below the Paco Basin at the Westinghouse Hanford Site. Has been used in the Basalt Waste Isolation Project to simulate nonisothermal groundwater flow in a heterogeneous anisotropic medium and heat transport in a water/<span class="hlt">rock</span> system near a high level nuclear waste repository. Allows three representations of the hydrogeologic system: an equivalent <span class="hlt">porous</span> continuum, a system of discrete, unfilled, and interconnecting fractures separated by impervious <span class="hlt">rock</span> mass, and a low permeability <span class="hlt">porous</span> continuum with several discrete, unfilled fractures traversing the medium. The calculation assumes local thermodynamic equilibrium between the <span class="hlt">rock</span> and groundwater, nonisothermal Darcian flow in the continuum portions of the <span class="hlt">rock</span>, and nonisothermal Poiseuille flow in discrete unfilled fractures. In addition, the code accounts for thermal loading within the elements, zero normal gradient and fixed boundary conditions for both temperature and hydraulic head, and simulation of the temperature and flow independently. The Q2DGEOM preprocessor was developed to generate, modify, plot and verify quadratic two dimensional finite element geometries. The BCGEN preprocessor generates the boundary conditions for head and temperature and ICGEN generates the initial conditions. The GRIDDER postprocessor interpolates nonregularly spaced nodal flow and temperature data onto a regular rectangular grid. CONTOUR plots and labels contour lines for a function of two variables and PARAM plots cross sections and time histories for a function of time and one or two spatial variables. NPRINT generates data tables that display the data along horizontal or vertical cross sections. VELPLT differentiates the hydraulic head and buoyancy data and plots the velocity vectors. The PATH postprocessor plots flow paths and computes the corresponding travel times.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA618019','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA618019"><span>Scattering from <span class="hlt">Rock</span> and <span class="hlt">Rock</span> Outcrops</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2014-09-30</p> <p>slope was determined from high-resolution interferometric bathymetry so that the global grazing angle of the 5 ideal mean seafloor could be mapped to...from exposed <span class="hlt">rock</span> on the seafloor , (i.e., individual <span class="hlt">rocks</span> and <span class="hlt">rock</span> outcrops) presents some of the most difficult challenges for modern MCM and ASW...classification tools. Inverse models based on forward models would be essential for using sonar systems for remote sensing of seafloor properties. An</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1018059','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1018059"><span>Metal filled <span class="hlt">porous</span> carbon</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Gross, Adam F.; Vajo, John J.; Cumberland, Robert W.; Liu, Ping; Salguero, Tina T.</p> <p>2011-03-22</p> <p>A <span class="hlt">porous</span> carbon scaffold with a surface and pores, the <span class="hlt">porous</span> carbon scaffold containing a primary metal and a secondary metal, where the primary metal is a metal that does not wet the surface of the pores of the carbon scaffold but wets the surface of the secondary metal, and the secondary metal is interspersed between the surface of the pores of the carbon scaffold and the primary metal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014RvGeo..52..468A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014RvGeo..52..468A"><span>Three-phase flow in <span class="hlt">porous</span> media: A review of experimental studies on relative permeability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alizadeh, A. H.; Piri, M.</p> <p>2014-09-01</p> <p>We present a detailed, synthesized review of experimental studies on three-phase relative permeability published since 1980. We provide comprehensive, yet highly focused, analysis of critical aspects of the field and their evolution over the last three decades. In particular, we review the effects of saturation history, wettability, spreading, and layer drainage on the measured flow properties. We also list all the processes, <span class="hlt">rock</span> types, fluid systems, and measurement techniques in order to provide a clear map for future studies. Behavior of the measured three-phase relative permeabilities with respect to <span class="hlt">fluid</span> <span class="hlt">saturations</span>, saturation histories, wettability of <span class="hlt">rock</span> samples, spreading characteristics, interfacial tensions, and other pertinent properties are carefully discussed. Studies that use a diverse set of experimental techniques and data analysis to deduce relative permeability are included. The experimental techniques that should be utilized to reduce uncertainty are also explored. We interpret the measured properties and outcomes of different studies and compare them to substantiate distinct trends at various saturation ranges and provide ideas for new studies. This is intended to distill a clear image of where the field stands and to allow composition of possible paths for future investigations. The areas of critical relevance that have not been investigated or require further studies are highlighted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6140657','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6140657"><span>Solidus of carbonated fertile peridotite under <span class="hlt">fluid-saturated</span> conditions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Falloon, T.J.; Green, D.H. )</p> <p>1990-03-01</p> <p>The solidus for a fertile peridotite composition (Hawaiian pyrolite) in the presence of a CO{sub 2}-H{sub 2}O fluid phase has been determined from 10 to 35 kbar. The intersection of the decarbonation reaction (olivine + diopside + CO{sub 2} {l reversible} orthopyroxene + dolomite) with the pyrolite solidus defines the point Q{prime}, located at 22 kbar and 940 C. At pressures less than Q{prime}, the solidus passes through a temperature maximum at kbar, 1060 C. The solidus is coincident with amphibole breakdown at pressures less than 16 kbar. At pressures above Q{prime}, the solidus is defined by the dissolution of crystalline carbonate into a sodic, dolomitic carbonatite melt. The solidus is at a temperature of 925 C at {approximately} 28 kbar. The solidus temperature above the point Q{prime} is similar to the solidus determined for Hawaiian pyrolite-H{sub 2}O-CO{sub 2} for small contents of H{sub 2}O (<0.3 wt%) and CO{sub 2} (<5 wt%), thus indicating that the primary sodic dolomitic carbonatite melt at both solidi has a very low and limited H{sub 2}O solubility. The new data clarify the roles of carbonatite melt, carbonated silicate melt, and H{sub 2}O-rich fluid in mantle conditions that are relatively oxidized (f{sub O{sub 2}} {approximately} MW to FMQ). In particular, a carbonatite melt + garnet lherzolite region is intersected by continental shield geothermal gradients, but such geotherms only intersect regions with carbonated silicate melt if perturbed to higher temperatures (kinked geotherm).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/873905','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/873905"><span>Discrimination of porosity and <span class="hlt">fluid</span> <span class="hlt">saturation</span> using seismic velocity analysis</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Berryman, James G.</p> <p>2001-01-01</p> <p>The method of the invention is employed for determining the state of saturation in a subterranean formation using only seismic velocity measurements (e.g., shear and compressional wave velocity data). Seismic velocity data collected from a region of the formation of like solid material properties can provide relatively accurate partial saturation data derived from a well-defined triangle plotted in a (.rho./.mu., .lambda./.mu.)-plane. When the seismic velocity data are collected over a large region of a formation having both like and unlike materials, the method first distinguishes the like materials by initially plotting the seismic velocity data in a (.rho./.lambda., .mu./.lambda.)-plane to determine regions of the formation having like solid material properties and porosity.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JSG....63...50F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JSG....63...50F"><span>Anisotropy of permeability in faulted <span class="hlt">porous</span> sandstones</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Farrell, N. J. C.; Healy, D.; Taylor, C. W.</p> <p>2014-06-01</p> <p>Studies of fault <span class="hlt">rock</span> permeabilities advance the understanding of fluid migration patterns around faults and contribute to predictions of fault stability. In this study a new model is proposed combining brittle deformation structures formed during faulting, with fluid flow through pores. It assesses the impact of faulting on the permeability anisotropy of <span class="hlt">porous</span> sandstone, hypothesising that the formation of fault related micro-scale deformation structures will alter the host <span class="hlt">rock</span> porosity organisation and create new permeability pathways. Core plugs and thin sections were sampled around a normal fault and oriented with respect to the fault plane. Anisotropy of permeability was determined in three orientations to the fault plane at ambient and confining pressures. Results show that permeabilities measured parallel to fault dip were up to 10 times higher than along fault strike permeability. Analysis of corresponding thin sections shows elongate pores oriented at a low angle to the maximum principal palaeo-stress (σ1) and parallel to fault dip, indicating that permeability anisotropy is produced by grain scale deformation mechanisms associated with faulting. Using a soil mechanics 'void cell model' this study shows how elongate pores could be produced in faulted <span class="hlt">porous</span> sandstone by compaction and reorganisation of grains through shearing and cataclasis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006PhDT.......109T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006PhDT.......109T"><span>Pore-scale petrophysical models for the simulation and combined interpretation of nuclear magnetic resonance and wide-band electromagnetic measurements of saturated <span class="hlt">rocks</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Toumelin, Emmanuel</p> <p></p> <p>The interpretation of well logs in terms of hydraulic permeability, irreducible and free <span class="hlt">fluid</span> <span class="hlt">saturations</span>, hydrocarbon grades, and wettability is currently approached with oversimplified models of electrical resistivity and nuclear magnetic resonance (NMR). Inconsistent interpretations arise in the presence of clay, complex <span class="hlt">rock</span> morphologies, and mixed wettabilities. Wide-band electromagnetic (WBEM) measurements in the kHz-GHz range are sensitive to all these petrophysical attributes but cannot be interpreted in an independent fashion. New interpretation methods are necessary that can effectively combine the resolving capabilities of NMR and WBEM measurements performed under complex petrophysical conditions. This dissertation develops numerical models to simulate NMR and WBEM measurements in saturated <span class="hlt">rocks</span> using explicit pore-scale spatial distributions of grains and saturating fluids. The purpose of such models is three-fold: (1) to describe the fundamental properties of NMR and electromagnetic measurements using pore-scale physics; (2) to benchmark the accuracy and reliability of standard macroscopic models used for the interpretation of NMR and WBEM measurements; and (3) to show the complementary nature of NMR and WBEM measurements for the petrophysical evaluation of complex petrophysical conditions. Two geometrical models are developed to simulate electrical conductivity, NMR, and WBEM measurements in saturated <span class="hlt">rocks</span>. The first model consists of continuous 3-dimensional dense packs of grains. Immiscible fluids are distributed in the ensuing pore-space with adherence to capillary and saturation history. Random walkers diffusing throughout these pore geometries accurately reproduce DC conductivity and NMR magnetization decay as functions of porosity, <span class="hlt">rock</span> morphology, saturation history, fluid types, wettability, <span class="hlt">rock</span> surface relaxation, and NMR pulse sequences. The second model is constructed with 2-dimensional digital pore maps, where pixels are assigned</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA157493','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA157493"><span>Geotechnical Descriptions of <span class="hlt">Rock</span> and <span class="hlt">Rock</span> Masses.</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1985-04-01</p> <p>user of the field log can relate to the general class of <span class="hlt">rock</span> being described. For example, the <span class="hlt">rock</span> name " syenite " might be qualified by adding "the...FELDSPAR PRE-S---- Coarne Texture Granite Syenite Qts ononite Honzonite Cabbro Peridotite (Platonic or to Qtx Diorite to Diorite Pyroxenite intrusive</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DFD.H3002K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DFD.H3002K"><span>Dynamics of clogging in drying <span class="hlt">porous</span> media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kaplan, C. Nadir; Mahadevan, L.</p> <p>2014-11-01</p> <p>Drying in <span class="hlt">porous</span> media pervades a range of phenomena from brine evaporation arrested in <span class="hlt">porous</span> bricks, causing efflorescence, i.e. salt aggregation on the surface where vapor leaves the medium, to clogging of reservoir <span class="hlt">rocks</span> via salt precipitation when carbon dioxide is injected for geological storage. During the process of drying, the permeability and porosity of the medium may change due to the solute accumulation as a function of the particle concentration, in turn affecting the evaporation rate and the dynamics of the fluid flow imposed by it. To examine the dynamics of these coupled quantities, we develop a multiphase model of the particulate flow of a saline suspension in a <span class="hlt">porous</span> medium, induced by evaporation. We further provide dimensional arguments as to how the salt concentration and the resulting change in permeability determine the transition between efflorescence and salt precipitation in the bulk. This research was supported by the Air Force Office of Scientific Research (AFOSR) under Award FA9550-09-1-0669-DOD35CAP and the Kavli Institute for Bionano Science and Technology at Harvard University.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015RScI...86i5101S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015RScI...86i5101S"><span>A dynamic pressure view cell for acoustic stimulation of fluids—Micro-bubble generation and fluid movement in <span class="hlt">porous</span> media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stewart, Robert A.; Shaw, J. M.</p> <p>2015-09-01</p> <p>The development and baseline operation of an acoustic view cell for observing fluids, and fluid-fluid and fluid-solid interfaces in <span class="hlt">porous</span> media over the frequency range of 10-5000 Hz is described. This range includes the industrially relevant frequency range 500-5000 Hz that is not covered by existing devices. Pressure waveforms of arbitrary shape are generated in a 17.46 mm ID by 200 mm and 690.5 mm long glass tubes at flow rates up to 200 ml/min using a syringe pump. Peak-to-peak amplitudes exceeding 80 kPa are readily realized at frequencies from 10 to 5000 Hz in bubble free fluids when actuated with 20 Vpp as exemplified using castor oil. At resonant frequencies, peak-to-peak pressure amplitudes exceeding 500 kPa were obtained (castor oil at 2100 Hz when actuated with 20 Vpp). Impacts of vibration on macroscopic liquid-liquid and liquid-vapour interfaces and interface movement are illustrated. Pressure wave transmission and attenuation in a <span class="hlt">fluid</span> <span class="hlt">saturated</span> <span class="hlt">porous</span> medium, randomly packed 250-330 μm spherical silica beads, is also demonstrated. Attenuation differences and frequency shifts in resonant peaks are used to detect the presence and generation of dispersed micro-bubbles (<180 μm diameter), and bubbles within <span class="hlt">porous</span> media that are not readily visualized. Envisioned applications include assessment of the impacts of vibration on reaction, mass transfer, and flow/flow pattern outcomes. This knowledge will inform laboratory and pilot scale process studies, where nuisance vibrations may affect the interpretation of process outcomes, and large scale or in situ processes in aquifers or hydrocarbon reservoirs where imposed vibration may be deployed to improve aspects of process performance. Future work will include miscible interface observation and quantitative measurements in the bulk and in <span class="hlt">porous</span> media where the roles of micro-bubbles comprise subjects of special interest.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26429474','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26429474"><span>A dynamic pressure view cell for acoustic stimulation of fluids--Micro-bubble generation and fluid movement in <span class="hlt">porous</span> media.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stewart, Robert A; Shaw, J M</p> <p>2015-09-01</p> <p>The development and baseline operation of an acoustic view cell for observing fluids, and fluid-fluid and fluid-solid interfaces in <span class="hlt">porous</span> media over the frequency range of 10-5000 Hz is described. This range includes the industrially relevant frequency range 500-5000 Hz that is not covered by existing devices. Pressure waveforms of arbitrary shape are generated in a 17.46 mm ID by 200 mm and 690.5 mm long glass tubes at flow rates up to 200 ml/min using a syringe pump. Peak-to-peak amplitudes exceeding 80 kPa are readily realized at frequencies from 10 to 5000 Hz in bubble free fluids when actuated with 20 Vpp as exemplified using castor oil. At resonant frequencies, peak-to-peak pressure amplitudes exceeding 500 kPa were obtained (castor oil at 2100 Hz when actuated with 20 Vpp). Impacts of vibration on macroscopic liquid-liquid and liquid-vapour interfaces and interface movement are illustrated. Pressure wave transmission and attenuation in a <span class="hlt">fluid</span> <span class="hlt">saturated</span> <span class="hlt">porous</span> medium, randomly packed 250-330 μm spherical silica beads, is also demonstrated. Attenuation differences and frequency shifts in resonant peaks are used to detect the presence and generation of dispersed micro-bubbles (<180 μm diameter), and bubbles within <span class="hlt">porous</span> media that are not readily visualized. Envisioned applications include assessment of the impacts of vibration on reaction, mass transfer, and flow/flow pattern outcomes. This knowledge will inform laboratory and pilot scale process studies, where nuisance vibrations may affect the interpretation of process outcomes, and large scale or in situ processes in aquifers or hydrocarbon reservoirs where imposed vibration may be deployed to improve aspects of process performance. Future work will include miscible interface observation and quantitative measurements in the bulk and in <span class="hlt">porous</span> media where the roles of micro-bubbles comprise subjects of special interest.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhyA..470...20A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhyA..470...20A"><span>Effects of finite wall thickness and sinusoidal heating on convection in nanofluid-saturated local thermal non-equilibrium <span class="hlt">porous</span> cavity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alsabery, A. I.; Chamkha, A. J.; Saleh, H.; Hashim, I.; Chanane, B.</p> <p>2017-03-01</p> <p>The effects of finite wall thickness and sinusoidal heating on convection in a nanofluid-saturated local thermal non-equilibrium (LTNE) <span class="hlt">porous</span> cavity are studied numerically using the finite difference method. The finite thickness vertical wall of the cavity is maintained at a constant temperature and the right wall is heated sinusoidally. The horizontal insulated walls allow no heat transfer to the surrounding. The Darcy law is used along with the Boussinesq approximation for the flow. Water-based nanofluids with Cu nanoparticles are chosen for investigation. The results of this study are obtained for various parameters such as the Rayleigh number, periodicity parameter, nanoparticles volume fraction, thermal conductivity ratio, ratio of wall thickness to its height and the modified conductivity ratio. Explanation for the influence of the various above-mentioned parameters on the streamlines, isotherms, local Nusselt number and the weighted average heat transfer is provided with regards to the thermal conductivities of nanoparticles suspended in the pure fluid and the <span class="hlt">porous</span> medium. It is shown that the overall heat transfer is significantly increased with the relative non-uniform heating. Further, the convection heat transfer is shown to be inhibited by the presence of the solid wall. The results have possible applications in the heat-storage <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> systems and the applications of the high power heat transfer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001ApSS..185..108B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001ApSS..185..108B"><span>Method of <span class="hlt">porous</span> diamond deposition on <span class="hlt">porous</span> silicon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baranauskas, Vitor; Peterlevitz, Alfredo C.; Chang, Dahge C.; Durrant, Steven F.</p> <p>2001-12-01</p> <p>In this paper, we discuss the experimental results of the fabrication of <span class="hlt">porous</span> diamond/<span class="hlt">porous</span> silicon and <span class="hlt">porous</span> diamond structures by chemical vapor deposition of diamond over a skeleton of <span class="hlt">porous</span> silicon, replicating the <span class="hlt">porous</span> surface geometry around the Si pores and also creating new <span class="hlt">porous</span> diamond structures. Scanning electron microscopy (SEM) revealed that the diamond nuclei are deposited on the top of the <span class="hlt">porous</span> silicon skeleton, forming isolated grains in the first nucleation stages, and then growing like the usual structure of most ceramic materials, making a self-sustained <span class="hlt">porous</span> diamond structure. Raman spectroscopy revealed that the diamond films are of good quality, close to that of diamond films grown on crystalline silicon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA16687.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA16687.html"><span>Zapped, Martian <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2013-02-20</p> <p>This image from the Mars Hand Lens Imager MAHLI on NASA Mars rover Curiosity shows details of <span class="hlt">rock</span> texture and color in an area where the rover Dust Removal Tool DRT brushed away dust that was on the <span class="hlt">rock</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=Rock+AND+Cycle&pg=2&id=EJ176258','ERIC'); return false;" href="https://eric.ed.gov/?q=Rock+AND+Cycle&pg=2&id=EJ176258"><span>The <span class="hlt">Rock</span> Cycle</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Singh, Raman J.; Bushee, Jonathan</p> <p>1977-01-01</p> <p>Presents a <span class="hlt">rock</span> cycle diagram suitable for use at the secondary or introductory college levels which separates <span class="hlt">rocks</span> formed on and below the surface, includes organic materials, and separates products from processes. (SL)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850037432&hterms=Rock+Cycle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DRock%2BCycle','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850037432&hterms=Rock+Cycle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DRock%2BCycle"><span>Theory of wing <span class="hlt">rock</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hsu, C.-H.; Lan, C. E.</p> <p>1985-01-01</p> <p>Wing <span class="hlt">rock</span> is one type of lateral-directional instabilities at high angles of attack. To predict wing <span class="hlt">rock</span> characteristics and to design airplanes to avoid wing <span class="hlt">rock</span>, parameters affecting wing <span class="hlt">rock</span> characteristics must be known. A new nonlinear aerodynamic model is developed to investigate the main aerodynamic nonlinearities causing wing <span class="hlt">rock</span>. In the present theory, the Beecham-Titchener asymptotic method is used to derive expressions for the limit-cycle amplitude and frequency of wing <span class="hlt">rock</span> from nonlinear flight dynamics equations. The resulting expressions are capable of explaining the existence of wing <span class="hlt">rock</span> for all types of aircraft. Wing <span class="hlt">rock</span> is developed by negative or weakly positive roll damping, and sustained by nonlinear aerodynamic roll damping. Good agreement between theoretical and experimental results is obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=rock&pg=4&id=EJ721669','ERIC'); return false;" href="http://eric.ed.gov/?q=rock&pg=4&id=EJ721669"><span><span class="hlt">Rocks</span> in Our Pockets</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Plummer, Donna; Kuhlman, Wilma</p> <p>2005-01-01</p> <p>To introduce students to <span class="hlt">rocks</span> and their characteristics, teacher can begin <span class="hlt">rock</span> units with the activities described in this article. Students need the ability to make simple observations using their senses and simple tools.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://files.eric.ed.gov/fulltext/EJ176258.pdf','ERIC'); return false;" href="http://files.eric.ed.gov/fulltext/EJ176258.pdf"><span>The <span class="hlt">Rock</span> Cycle</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Singh, Raman J.; Bushee, Jonathan</p> <p>1977-01-01</p> <p>Presents a <span class="hlt">rock</span> cycle diagram suitable for use at the secondary or introductory college levels which separates <span class="hlt">rocks</span> formed on and below the surface, includes organic materials, and separates products from processes. (SL)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=growing+AND+crystals&id=EJ354652','ERIC'); return false;" href="http://eric.ed.gov/?q=growing+AND+crystals&id=EJ354652"><span><span class="hlt">Rocks</span> and Minerals.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Naturescope, 1987</p> <p>1987-01-01</p> <p>Provides background information on <span class="hlt">rocks</span> and minerals, including the unique characteristics of each. Teaching activities on <span class="hlt">rock</span>-hunting and identification, mineral configurations, mystery minerals, and growing crystals are provided. Reproducible worksheets are included for two of the activities. (TW)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=history+AND+rocks&pg=7&id=EJ354652','ERIC'); return false;" href="https://eric.ed.gov/?q=history+AND+rocks&pg=7&id=EJ354652"><span><span class="hlt">Rocks</span> and Minerals.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Naturescope, 1987</p> <p>1987-01-01</p> <p>Provides background information on <span class="hlt">rocks</span> and minerals, including the unique characteristics of each. Teaching activities on <span class="hlt">rock</span>-hunting and identification, mineral configurations, mystery minerals, and growing crystals are provided. Reproducible worksheets are included for two of the activities. (TW)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=rocks&pg=4&id=EJ721669','ERIC'); return false;" href="https://eric.ed.gov/?q=rocks&pg=4&id=EJ721669"><span><span class="hlt">Rocks</span> in Our Pockets</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Plummer, Donna; Kuhlman, Wilma</p> <p>2005-01-01</p> <p>To introduce students to <span class="hlt">rocks</span> and their characteristics, teacher can begin <span class="hlt">rock</span> units with the activities described in this article. Students need the ability to make simple observations using their senses and simple tools.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1913955S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1913955S"><span>Investigating anomalous transport of electrolytes in charged <span class="hlt">porous</span> media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Skjøde Bolet, Asger Johannes; Mathiesen, Joachim</p> <p>2017-04-01</p> <p>Surface charge is know to play an important role in microfluidics devices when dealing with electrolytes and their transport properties. Similarly, surface charge could play a role for transport in <span class="hlt">porous</span> <span class="hlt">rock</span> with submicron pore sizes. Estimates of the streaming potentials and electro osmotic are mostly considered in simple geometries both using analytic and numerical tools, however it is unclear at present how realistic complex geometries will modify the dynamics. Our work have focused on doing numerical studies of the full three-dimensional Stokes-Poisson-Nernst-Planck problem for electrolyte transport in <span class="hlt">porous</span> <span class="hlt">rock</span>. As the numerical implementation, we have used a finite element solver made using the FEniCS project code base, which can both solve for a steady state configuration and the full transient. In the presentation, we will show our results on anomalous transport due to electro kinetic effects such as the streaming potential or the electro osmotic effect.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6092700','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6092700"><span>Principles of <span class="hlt">rock</span> deformation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nicolas, A.</p> <p>1987-01-01</p> <p>This text focuses on the recent achievements in the analysis of <span class="hlt">rock</span> deformation. It gives an analytical presentation of the essential structures in terms of kinetic and dynamic interpretation. The physical properties underlying the interpretation of <span class="hlt">rock</span> structures are exposed in simple terms. Emphasized in the book are: the role of fluids in <span class="hlt">rock</span> fracturing; the kinematic analysis of magnetic flow structures; the application of crystalline plasticity to the kinematic and dynamic analysis of the large deformation imprinted in many metamorphic <span class="hlt">rocks</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('//www.loc.gov/pictures/collection/hh/item/ca1230.photos.011797p/','SCIGOV-HHH'); return false;" href="//www.loc.gov/pictures/collection/hh/item/ca1230.photos.011797p/"><span>68. LITTLE <span class="hlt">ROCK</span> AND PALMDALE IRRIGATION DISTRICT, LITTLE <span class="hlt">ROCK</span> DAM: ...</span></a></p> <p><a target="_blank" href="http://www.loc.gov/pictures/collection/hh/">Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey</a></p> <p></p> <p></p> <p>68. LITTLE <span class="hlt">ROCK</span> AND PALMDALE IRRIGATION DISTRICT, LITTLE <span class="hlt">ROCK</span> DAM: STRESS SHEET, SHEET 4; MAY, 1918. Littlerock Water District files. - Little <span class="hlt">Rock</span> Creek Dam, Little <span class="hlt">Rock</span> Creek, Littlerock, Los Angeles County, CA</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1255655','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1255655"><span>Tracking interface and common curve dynamics for two-fluid flow in <span class="hlt">porous</span> media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mcclure, James E.; Miller, Cass T.; Gray, W. G.; Berrill, Mark A.</p> <p>2016-04-29</p> <p>Pore-scale studies of multiphase flow in <span class="hlt">porous</span> medium systems can be used to understand transport mechanisms and quantitatively determine closure relations that better incorporate microscale physics into macroscale models. Multiphase flow simulators constructed using the lattice Boltzmann method provide a means to conduct such studies, including both the equilibrium and dynamic aspects. Moving, storing, and analyzing the large state space presents a computational challenge when highly-resolved models are applied. We present an approach to simulate multiphase flow processes in which in-situ analysis is applied to track multiphase flow dynamics at high temporal resolution. We compute a comprehensive set of measures of the phase distributions and the system dynamics, which can be used to aid fundamental understanding and inform closure relations for macroscale models. The measures computed include microscale point representations and macroscale averages of <span class="hlt">fluid</span> <span class="hlt">saturations</span>, the pressure and velocity of the fluid phases, interfacial areas, interfacial curvatures, interface and common curve velocities, interfacial orientation tensors, phase velocities and the contact angle between the fluid-fluid interface and the solid surface. Test cases are studied to validate the approach and illustrate how measures of system state can be obtained and used to inform macroscopic theory.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1255655-tracking-interface-common-curve-dynamics-two-fluid-flow-porous-media','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1255655-tracking-interface-common-curve-dynamics-two-fluid-flow-porous-media"><span>Tracking interface and common curve dynamics for two-fluid flow in <span class="hlt">porous</span> media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Mcclure, James E.; Miller, Cass T.; Gray, W. G.; ...</p> <p>2016-04-29</p> <p>Pore-scale studies of multiphase flow in <span class="hlt">porous</span> medium systems can be used to understand transport mechanisms and quantitatively determine closure relations that better incorporate microscale physics into macroscale models. Multiphase flow simulators constructed using the lattice Boltzmann method provide a means to conduct such studies, including both the equilibrium and dynamic aspects. Moving, storing, and analyzing the large state space presents a computational challenge when highly-resolved models are applied. We present an approach to simulate multiphase flow processes in which in-situ analysis is applied to track multiphase flow dynamics at high temporal resolution. We compute a comprehensive set of measuresmore » of the phase distributions and the system dynamics, which can be used to aid fundamental understanding and inform closure relations for macroscale models. The measures computed include microscale point representations and macroscale averages of <span class="hlt">fluid</span> <span class="hlt">saturations</span>, the pressure and velocity of the fluid phases, interfacial areas, interfacial curvatures, interface and common curve velocities, interfacial orientation tensors, phase velocities and the contact angle between the fluid-fluid interface and the solid surface. Test cases are studied to validate the approach and illustrate how measures of system state can be obtained and used to inform macroscopic theory.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016WRR....52.2601D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016WRR....52.2601D"><span>An adaptive lattice Boltzmann scheme for modeling two-fluid-phase flow in <span class="hlt">porous</span> medium systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dye, Amanda L.; McClure, James E.; Adalsteinsson, David; Miller, Cass T.</p> <p>2016-04-01</p> <p>We formulate a multiple-relaxation-time (MRT) lattice-Boltzmann method (LBM) to simulate two-fluid-phase flow in <span class="hlt">porous</span> medium systems. The MRT LBM is applied to simulate the displacement of a wetting fluid by a nonwetting fluid in a system corresponding to a microfluidic cell. Analysis of the simulation shows widely varying time scales for the dynamics of fluid pressures, <span class="hlt">fluid</span> <span class="hlt">saturations</span>, and interfacial curvatures that are typical characteristics of such systems. Displacement phenomena include Haines jumps, which are relatively short duration isolated events of rapid fluid displacement driven by capillary instability. An adaptive algorithm is advanced using a level-set method to locate interfaces and estimate their rate of advancement. Because the displacement dynamics are confined to the interfacial regions for a majority of the relaxation time, the computational effort is focused on these regions. The proposed algorithm is shown to reduce computational effort by an order of magnitude, while yielding essentially identical solutions to a conventional fully coupled approach. The challenges posed by Haines jumps are also resolved by the adaptive algorithm. Possible extensions to the advanced method are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1255655','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1255655"><span>Tracking interface and common curve dynamics for two-fluid flow in <span class="hlt">porous</span> media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mcclure, James E.; Miller, Cass T.; Gray, W. G.; Berrill, Mark A.</p> <p>2016-04-29</p> <p>Pore-scale studies of multiphase flow in <span class="hlt">porous</span> medium systems can be used to understand transport mechanisms and quantitatively determine closure relations that better incorporate microscale physics into macroscale models. Multiphase flow simulators constructed using the lattice Boltzmann method provide a means to conduct such studies, including both the equilibrium and dynamic aspects. Moving, storing, and analyzing the large state space presents a computational challenge when highly-resolved models are applied. We present an approach to simulate multiphase flow processes in which in-situ analysis is applied to track multiphase flow dynamics at high temporal resolution. We compute a comprehensive set of measures of the phase distributions and the system dynamics, which can be used to aid fundamental understanding and inform closure relations for macroscale models. The measures computed include microscale point representations and macroscale averages of <span class="hlt">fluid</span> <span class="hlt">saturations</span>, the pressure and velocity of the fluid phases, interfacial areas, interfacial curvatures, interface and common curve velocities, interfacial orientation tensors, phase velocities and the contact angle between the fluid-fluid interface and the solid surface. Test cases are studied to validate the approach and illustrate how measures of system state can be obtained and used to inform macroscopic theory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=pet&pg=3&id=EJ782667','ERIC'); return false;" href="https://eric.ed.gov/?q=pet&pg=3&id=EJ782667"><span>My Pet <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Lark, Adam; Kramp, Robyne; Nurnberger-Haag, Julie</p> <p>2008-01-01</p> <p>Many teachers and students have experienced the classic pet <span class="hlt">rock</span> experiment in conjunction with a geology unit. A teacher has students bring in a "pet" <span class="hlt">rock</span> found outside of school, and the students run geologic tests on the <span class="hlt">rock</span>. The tests include determining relative hardness using Mohs scale, checking for magnetization, and assessing luster.…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=Hardness&id=EJ782667','ERIC'); return false;" href="http://eric.ed.gov/?q=Hardness&id=EJ782667"><span>My Pet <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Lark, Adam; Kramp, Robyne; Nurnberger-Haag, Julie</p> <p>2008-01-01</p> <p>Many teachers and students have experienced the classic pet <span class="hlt">rock</span> experiment in conjunction with a geology unit. A teacher has students bring in a "pet" <span class="hlt">rock</span> found outside of school, and the students run geologic tests on the <span class="hlt">rock</span>. The tests include determining relative hardness using Mohs scale, checking for magnetization, and assessing luster.…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JMPSo..82..186M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JMPSo..82..186M"><span>Minimization principles for the coupled problem of Darcy-Biot-type fluid transport in <span class="hlt">porous</span> media linked to phase field modeling of fracture</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miehe, Christian; Mauthe, Steffen; Teichtmeister, Stephan</p> <p>2015-09-01</p> <p>This work develops new minimization and saddle point principles for the coupled problem of Darcy-Biot-type fluid transport in <span class="hlt">porous</span> media at fracture. It shows that the quasi-static problem of elastically deforming, <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> media is related to a minimization principle for the evolution problem. This two-field principle determines the rate of deformation and the fluid mass flux vector. It provides a canonically compact model structure, where the stress equilibrium and the inverse Darcy's law appear as the Euler equations of a variational statement. A Legendre transformation of the dissipation potential relates the minimization principle to a characteristic three field saddle point principle, whose Euler equations determine the evolutions of deformation and fluid content as well as Darcy's law. A further geometric assumption results in modified variational principles for a simplified theory, where the fluid content is linked to the volumetric deformation. The existence of these variational principles underlines inherent symmetries of Darcy-Biot theories of <span class="hlt">porous</span> media. This can be exploited in the numerical implementation by the construction of time- and space-discrete variational principles, which fully determine the update problems of typical time stepping schemes. Here, the proposed minimization principle for the coupled problem is advantageous with regard to a new unconstrained stable finite element design, while space discretizations of the saddle point principles are constrained by the LBB condition. The variational principles developed provide the most fundamental approach to the discretization of nonlinear fluid-structure interactions, showing symmetric systems in algebraic update procedures. They also provide an excellent starting point for extensions towards more complex problems. This is demonstrated by developing a minimization principle for a phase field description of fracture in <span class="hlt">fluid-saturated</span> <span class="hlt">porous</span> media. It is designed for an</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21869999','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21869999"><span><span class="hlt">Porous</span> silicon nanowires.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Qu, Yongquan; Zhou, Hailong; Duan, Xiangfeng</p> <p>2011-10-05</p> <p>In this mini-review, we summarize recent progress in the synthesis, properties and applications of a new type of one-dimensional nanostructures-single crystalline <span class="hlt">porous</span> silicon nanowires. The growth of <span class="hlt">porous</span> silicon nanowires starting from both p- and n-type Si wafers with a variety of dopant concentrations can be achieved through either one-step or two-step reactions. The mechanistic studies indicate the dopant concentration of Si wafers, oxidizer concentration, etching time and temperature can affect the morphology of the as-etched silicon nanowires. The <span class="hlt">porous</span> silicon nanowires are both optically and electronically active and have been explored for potential applications in diverse areas including photocatalysis, lithium ion batteries, gas sensors and drug delivery.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1040878','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1040878"><span><span class="hlt">Porous</span> material neutron detector</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Diawara, Yacouba [Oak Ridge, TN; Kocsis, Menyhert [Venon, FR</p> <p>2012-04-10</p> <p>A neutron detector employs a <span class="hlt">porous</span> material layer including pores between nanoparticles. The composition of the nanoparticles is selected to cause emission of electrons upon detection of a neutron. The nanoparticles have a maximum dimension that is in the range from 0.1 micron to 1 millimeter, and can be sintered with pores thereamongst. A passing radiation generates electrons at one or more nanoparticles, some of which are scattered into a pore and directed toward a direction opposite to the applied electrical field. These electrons travel through the pore and collide with additional nanoparticles, which generate more electrons. The electrons are amplified in a cascade reaction that occurs along the pores behind the initial detection point. An electron amplification device may be placed behind the <span class="hlt">porous</span> material layer to further amplify the electrons exiting the <span class="hlt">porous</span> material layer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3236246','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3236246"><span><span class="hlt">Porous</span> Silicon Nanowires</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Qu, Yongquan; Zhou, Hailong; Duan, Xiangfeng</p> <p>2011-01-01</p> <p>In this minreview, we summarize recent progress in the synthesis, properties and applications of a new type of one-dimensional nanostructures — single crystalline <span class="hlt">porous</span> silicon nanowires. The growth of <span class="hlt">porous</span> silicon nanowires starting from both p- and n-type Si wafers with a variety of dopant concentrations can be achieved through either one-step or two-step reactions. The mechanistic studies indicate the dopant concentration of Si wafers, oxidizer concentration, etching time and temperature can affect the morphology of the as-etched silicon nanowires. The <span class="hlt">porous</span> silicon nanowires are both optically and electronically active and have been explored for potential applications in diverse areas including photocatalysis, lithium ion battery, gas sensor and drug delivery. PMID:21869999</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=104339&keyword=fluid+AND+mechanics&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78809178&CFTOKEN=29331421','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=104339&keyword=fluid+AND+mechanics&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78809178&CFTOKEN=29331421"><span>FLUID TRANSPORT THROUGH <span class="hlt">POROUS</span> MEDIA</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>Fluid transport through <span class="hlt">porous</span> media is a relevant topic to many scientific and engineering fields. Soil scientists, civil engineers, hydrologists and hydrogeologists are concerned with the transport of water, gases and nonaqueous phase liquid contaminants through <span class="hlt">porous</span> earth m...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=104339&keyword=understanding+AND+physics&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=104339&keyword=understanding+AND+physics&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>FLUID TRANSPORT THROUGH <span class="hlt">POROUS</span> MEDIA</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>Fluid transport through <span class="hlt">porous</span> media is a relevant topic to many scientific and engineering fields. Soil scientists, civil engineers, hydrologists and hydrogeologists are concerned with the transport of water, gases and nonaqueous phase liquid contaminants through <span class="hlt">porous</span> earth m...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/70737','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/70737"><span>Predicting the permeability of sedimentary <span class="hlt">rocks</span> from microstructure</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Schlueter, E.M.</p> <p>1995-01-01</p> <p>Permeability is linked to other properties of <span class="hlt">porous</span> media such as capillary pressure and relative permeability. In order to understand the relationships, one has to understand how all those properties are conditioned by the connectivity and geometrical properties of the pore space. In this study, we look at a natural <span class="hlt">porous</span> material which is defined as a two-phase material in which the interconnected pore space constitutes one phase and the solid matrix the other. Laboratory samples are tested using fluid flow experiments to determine the relationship of macroscopic properties such as permeability to <span class="hlt">rock</span> microstructure. Kozeny-Carman and other equations are developed to further quantify these relationships.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.H21M..06A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.H21M..06A"><span>Barometric Pumping of a Fractured <span class="hlt">Porous</span> Medium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Adler, P. M.; Mourzenko, V.; Thovert, J. F.; Pili, E.; Guillon, S.</p> <p>2014-12-01</p> <p>Fluctuations in the ambient atmospheric pressure result in motion of air in <span class="hlt">porous</span> fractured media. This mechanism, known as barometric pumping, efficiently transports gaseous species through the vadose zone to the atmosphere. This is of interest in fields, such as transport of trace gases from soil to atmosphere, remediation of contaminated sites, radon in buildings, leakage from carbon sequestration sites and detection of nuclear explosions. The fractures are modeled as polygonal plane surfaces with a given transmissivity embedded in a permeable matrix. The slightly compressible fluid obeys Darcy's law in these two media with exchanges between them. The solute obeys convection-diffusion equations in both media again with exchanges. The fractures and the <span class="hlt">porous</span> medium are meshed by triangles and tetrahedra, respectively. The equations are discretized by the finite volume method. A Flux Limiting Scheme diminishes numerical dispersion ; the solute transfer between the fractures and the <span class="hlt">porous</span> medium is precisely evaluated. The resulting equations are solved by conjugate gradient algorithms. This model is applied to the Roselend Natural Laboratory. At a 55 m depth, a sealed cavity allows for gas release experiments across fractured <span class="hlt">porous</span> <span class="hlt">rocks</span> in the unsaturated zone. The fractures are hexagons with a radius of 5m; their density is larger than 2.4 10-3 m-3; the aperture is about 0.5 mm. The pressure fluctuations are sinusoidal, of amplitude 0.01 bar and period 1 week. The solute concentration is equal to 1 at the bottom. Systematic results will be presented. First, the precision of the calculations is assessed. Second, the pressure and solute concentration fields are displayed and discussed. Third, the influence of the major parameters (fracture density, aperture, porosity, diffusion coefficient,…) is illustrated and discussed. These results are discussed in terms of the amplification of solute transfer to the ground surface by the pressure fluctuations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1289998','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1289998"><span><span class="hlt">Porous</span> block nanofiber composite filters</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ginley, David S.; Curtis, Calvin J.; Miedaner, Alexander; Weiss, Alan J.; Paddock, Arnold</p> <p>2016-08-09</p> <p><span class="hlt">Porous</span> block nano-fiber composite (110), a filtration system (10) and methods of using the same are disclosed. An exemplary <span class="hlt">porous</span> block nano-fiber composite (110) includes a <span class="hlt">porous</span> block (100) having one or more pores (200). The <span class="hlt">porous</span> block nano-fiber composite (110) also includes a plurality of inorganic nano-fibers (211) formed within at least one of the pores (200).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JCoPh.345..768B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JCoPh.345..768B"><span>Flow simulations in <span class="hlt">porous</span> media with immersed intersecting fractures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Berrone, Stefano; Pieraccini, Sandra; Scialò, Stefano</p> <p>2017-09-01</p> <p>A novel approach for fully 3D flow simulations in <span class="hlt">porous</span> media with immersed networks of fractures is presented. The method is based on the discrete fracture and matrix model, in which fractures are represented as two-dimensional objects in a three-dimensional <span class="hlt">porous</span> matrix. The problem, written in primal formulation on both the fractures and the <span class="hlt">porous</span> matrix, is solved resorting to the constrained minimization of a properly designed cost functional that expresses the matching conditions at fracture-fracture and fracture-matrix interfaces. The method, originally conceived for intricate fracture networks in impervious <span class="hlt">rock</span> matrices, is here extended to fractures in a <span class="hlt">porous</span> permeable <span class="hlt">rock</span> matrix. The purpose of the optimization approach is to allow for an easy meshing process, independent of the geometrical complexity of the domain, and for a robust and efficient resolution tool, relying on a strong parallelism. The present work is devoted to the presentation of the new method and of its applicability to flow simulations in poro-fractured domains.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910000511&hterms=solid+state+microwave&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dsolid%2Bstate%2Bmicrowave','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910000511&hterms=solid+state+microwave&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dsolid%2Bstate%2Bmicrowave"><span>Chemically Layered <span class="hlt">Porous</span> Solids</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Koontz, Steve</p> <p>1991-01-01</p> <p>Aerogels and other <span class="hlt">porous</span> solids in which surfaces of pores have chemical properties varying with depth below macroscopic surfaces prepared by sequences of chemical treatments. <span class="hlt">Porous</span> glass or silica bead treated to make two depth zones having different chemical properties. Beads dropped along tube filled with flowing gas containing atomic oxygen, generated in microwave discharge. General class of materials treatable include oxides of aluminum, silicon, zirconium, tin, titanium, and nickel, and mixtures of these oxides. Potential uses of treated materials include chromatographic separations, membrane separations, controlled releases of chemicals, and catalysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/416137','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/416137"><span><span class="hlt">Porous</span> silicon gettering</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tsuo, Y.S.; Menna, P.; Pitts, J.R.</p> <p>1996-05-01</p> <p>The authors have studied a novel extrinsic gettering method that uses the large surface areas produced by a <span class="hlt">porous</span>-silicon etch as gettering sites. The annealing step of the gettering used a high-flux solar furnace. They found that a high density of photons during annealing enhanced the impurity diffusion to the gettering sites. The authors used metallurgical-grade Si (MG-Si) prepared by directional solidification casing as the starting material. They propose to use <span class="hlt">porous</span>-silicon-gettered MG-Si as a low-cost epitaxial substrate for polycrystalline silicon thin-film growth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA06265&hterms=vesicles&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dvesicles','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA06265&hterms=vesicles&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dvesicles"><span>Spirit Guidepost, 'Plymouth <span class="hlt">Rock</span>'</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/> NASA's Mars Exploration Rover Spirit took this panoramic camera image during Spirit's 152nd sol, on June 7, 2004. The <span class="hlt">rock</span>, informally named 'Plymouth <span class="hlt">Rock</span>,' is approximately 90 centimeters (35 inches) across and 50 centimeters (20 inches) tall. Spirit did not spend any time studying Plymouth <span class="hlt">Rock</span>, but rover controllers used it as a guide to maneuver Spirit closer to the 'Columbia Hills.' Like most of the <span class="hlt">rocks</span> found at the Gusev crater location, Plymouth is most likely a basalt. The tiny vesicles pitting the <span class="hlt">rock</span>'s surface further indicate its volcanic origin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.usbr.gov/tsc/techreferences/mands/mands-pdfs/Rock%20Ramp%20Design%20Guidelines_09-2007_508.pdf','USGSPUBS'); return false;" href="https://www.usbr.gov/tsc/techreferences/mands/mands-pdfs/Rock%20Ramp%20Design%20Guidelines_09-2007_508.pdf"><span><span class="hlt">Rock</span> ramp design guidelines</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Mooney, David M.; Holmquist-Johnson, Christopher L.; Broderick, Susan</p> <p>2007-01-01</p> <p><span class="hlt">Rock</span> ramps or roughened channels consist of steep reaches stabilized by large immobile material (riprap). Primary objectives for <span class="hlt">rock</span> ramps include: Create adequate head for diversionMaintain fish passage during low-flow conditionsMaintain hydraulic conveyance during high-flow conditionsSecondary objectives for <span class="hlt">rock</span> ramp design include:Emulate natural systemsMinimize costsThe <span class="hlt">rock</span> ramp consists of a low-flow channel designed to maintain biologically adequate depth and velocity conditions during periods of small discharges. The remainder of the ramp is designed to withstand and pass large flows with minimal structural damage. The following chapters outline a process for designing <span class="hlt">rock</span> ramps.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6370269','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/6370269"><span><span class="hlt">Porous</span> metallic bodies</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Landingham, R.L.</p> <p>1984-03-13</p> <p><span class="hlt">Porous</span> metallic bodies having a substantially uniform pore size of less than about 200 microns and a density of less than about 25 percent theoretical, as well as the method for making them, are disclosed. Group IIA, IIIB, IVB, VB, and rare earth metal hydrides a</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950065537&hterms=zinc+air+battery&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dzinc%2Bair%2Bbattery','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950065537&hterms=zinc+air+battery&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dzinc%2Bair%2Bbattery"><span>Hydrophobic, <span class="hlt">Porous</span> Battery Boxes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bragg, Bobby J.; Casey, John E., Jr.</p> <p>1995-01-01</p> <p>Boxes made of <span class="hlt">porous</span>, hydrophobic polymers developed to contain aqueous potassium hydroxide electrolyte solutions of zinc/air batteries while allowing air to diffuse in as needed for operation. Used on other types of batteries for in-cabin use in which electrolytes aqueous and from which gases generated during operation must be vented without allowing electrolytes to leak out.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985NIMPB...9..317E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985NIMPB...9..317E"><span>Analysis of <span class="hlt">porous</span> silicon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Earwaker, L. G.; Farr, J. P. G.; Grzeszczyk, P. E.; Sturland, I.; Keen, J. M.</p> <p>1985-06-01</p> <p><span class="hlt">Porous</span> silicon, suitable after oxidation for dielectric isolation, has been produced successfully by anodizing silicon in strong HF. The oxidized layer has been shown to have promise in device manufacture, providing high packing densities and radiation hardness. Anodizing has been carried out using both single and double cells, following the effects of current density. HF concentration and silicon resistivity. The resultant <span class="hlt">porous</span> layers have been characterised with respect to composition and structure. The materials produced differ considerably in lattice strain, composition and reactivities. Prompt radiation analyses 19F(p,αγ), 16O(d,α), 12C(d,p), are useful for monitoring the anodizing procedures and subsequent oxidation: currently, interest centres on the mechanistic information obtained. RBS analysis using α-particles gives a much lower Si response from <span class="hlt">porous</span> than from bulk silicon. Glancing angle proton recoil analyses reveal considerable quantities of hydrogen in the <span class="hlt">porous</span> layers. These mutually consistent findings have considerable mechanistic significance; extensive Si-H bonding occurs following a 2 equivalent Faradaic process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/207248','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/207248"><span>Surface potential and permeability of <span class="hlt">rock</span> cores under asphaltenic oil flow conditions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Alkafeef, S.F.; Gochin, R.J.; Smith, A.L.</p> <p>1995-12-31</p> <p>The surface properties, wetting behaviour and permeability of <span class="hlt">rock</span> samples are central to understanding recovery behaviour in oil reservoirs. This paper will present a method new to petroleum engineering to show how area/length ratios for <span class="hlt">porous</span> systems can be obtained by combining streaming potential and streaming current measurements on <span class="hlt">rock</span> cores. This has allows streaming current measurements (independent of surface conductivity errors) to be made on <span class="hlt">rock</span> samples using hydrocarbon solvents with increasing concentrations of asphaltene. Negative surface potentials for the <span class="hlt">rock</span> became steadily more positive as asphaltene coated the pore surfaces, with permeability reduction agreeing well with petrographic analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhDT........96T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhDT........96T"><span>Adhesion of liquids to <span class="hlt">porous</span> materials and fibers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Trofimov, Artem</p> <p></p> <p>This research is centered on the analysis of adhesion properties of <span class="hlt">porous</span> materials and fibers of elliptical shapes. Composites are a unique class of materials having properties, which could not be achieved by either of the constituent materials alone. Composites with <span class="hlt">porous</span> filler are put into service in buildings, roads, bridges, etc. Fiber-reinforced composites are actively involved in flight vehicles, automobiles, boats, and dozens of other products. In the first part of this study we developed a procedure for evaluation of adhesion of liquids to <span class="hlt">porous</span> solids, where water, hexadecane and asphalt binder and different <span class="hlt">rocks</span> were studied to illustrate the methodology. An experimental protocol to evaluate the work of adhesion, a characteristic thermodynamic parameter of the liquid/<span class="hlt">porous</span> solid pair, was discussed and a mathematical model describing the kinetics of liquid penetration into inhomogeneous <span class="hlt">porous</span> material was developed and used for interpretation of the experiments. The second part is devoted to the analysis of interactions of liquids with circular and elliptical wires. The behavior of menisci embracing the fiber in the capillary rise experiment was investigated. In particular, we study the profiles of the contact line around cylinders, contact angle, and the work of adhesion of a set of different liquids. Compared to the circular wires, elliptical wires produced taller menisci, hence the wetted area increases. It is expected that the kinetics of resin impregnation into a preforms made of elliptical fibers will significantly change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRB..122.1726L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRB..122.1726L"><span>Self-similar distributions of fluid velocity and stress heterogeneity in a dissolving <span class="hlt">porous</span> limestone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Linga, Gaute; Mathiesen, Joachim; Renard, François</p> <p>2017-03-01</p> <p>In a <span class="hlt">porous</span> <span class="hlt">rock</span>, the spatial distribution of the pore space induces a strong heterogeneity in fluid flow rates and in the stress distribution in the <span class="hlt">rock</span> mass. If the <span class="hlt">rock</span> microstructure evolves through time, for example, by dissolution, fluid flow and stress will evolve accordingly. Here we consider a core sample of <span class="hlt">porous</span> limestone that has undergone several steps of dissolution. Based on 3-D X-ray tomography scans, we calculate numerically the coupled system of fluid flow in the pore space and stress in the solid. We determine how the flow field affects the stress distribution both at the pore wall surface and in the bulk of the solid matrix. We show that during dissolution, the heterogeneous stress evolves in a self-similar manner as the porosity is increased. Conversely, the fluid velocity shows a stretched exponential distribution. The scalings of these common master distributions offer a unified description of the porosity evolution, pore flow, and the heterogeneity in stress for a <span class="hlt">rock</span> with evolving microstructure. Moreover, the probability density functions of stress invariants (mechanical pressure or von Mises stress) display heavy tails toward large stresses. If these results can be extended to other kinds of <span class="hlt">rocks</span>, they provide an additional explanation of the sensitivity to failure of <span class="hlt">porous</span> <span class="hlt">rocks</span> under slight changes of stress.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10163772','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10163772"><span>Predicting the transport properties of sedimentary <span class="hlt">rocks</span> from microgeometry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Schlueter, E.M.</p> <p>1993-01-01</p> <p>We investigate through analysis and experiment how pore geometry, topology, and the physics and chemistry of mineral-fluid and fluid-fluid interactions affect the flow of fluids through consolidated/partially consolidated <span class="hlt">porous</span> media. Our approach is to measure fluid permeability and electrical conductivity of <span class="hlt">rock</span> samples using single and multiple fluid phases that can be frozen in place (wetting and nonwetting) over a range of pore pressures. These experiments are analyzed in terms of the microphysics and microchemistry of the processes involved to provide a theoretical basis for the macroscopic constitutive relationships between fluid-flow and geophysical properties that we develop. The purpose of these experiments and their analyses is to advance the understanding of the mechanisms and factors that control fluid transport in <span class="hlt">porous</span> media. This understanding is important in characterizing <span class="hlt">porous</span> media properties and heterogeneities before simulating and monitoring the progress of complex flow processes at the field scale in permeable media.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10115065','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10115065"><span>Predicting the transport properties of sedimentary <span class="hlt">rocks</span> from microgeometry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Schlueter, E.M.</p> <p>1995-02-01</p> <p>The author investigates through analysis and experiment how pore geometry, topology, and the physics and chemistry of mineral-fluid and fluid-fluid interactions affect the flow of fluids through consolidated/partially consolidated <span class="hlt">porous</span> media. The approach is to measure fluid permeability and electrical conductivity of <span class="hlt">rock</span> samples using single and multiple fluid phases that can be frozen in place (wetting and nonwetting) over a range of pore pressures. These experiments are analyzed in terms of the microphysics and microchemistry of the processes involved to provide a theoretical basis for the macroscopic constitutive relationships between fluid-flow and geophysical properties that the authors develop. The purpose of these experiments and their analyses is to advance the understanding of the mechanisms and factors that control fluid transport in <span class="hlt">porous</span> media. This understanding is important in characterizing <span class="hlt">porous</span> media properties and heterogeneities before simulating and monitoring the progress of complex flow processes at the field scale in permeable media.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012542','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012542"><span>Friction of <span class="hlt">rocks</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Byerlee, J.</p> <p>1978-01-01</p> <p>Experimental results in the published literature show that at low normal stress the shear stress required to slide one <span class="hlt">rock</span> over another varies widely between experiments. This is because at low stress <span class="hlt">rock</span> friction is strongly dependent on surface roughness. At high normal stress that effect is diminished and the friction is nearly independent of <span class="hlt">rock</span> type. If the sliding surfaces are separated by gouge composed of Montmorillonite or vermiculite the friction can be very low. ?? 1978 Birkha??user Verlag.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003PhDT........23Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003PhDT........23Z"><span><span class="hlt">Porous</span> bioactive materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Kai</p> <p></p> <p>Bioactive materials chemically bond to tissues through the development of biologically active apatite. <span class="hlt">Porous</span> structures in biomaterials are designed to enhance bioactivity, grow artificial tissues and achieve better integration with host tissues in the body. The goal of this research is to design, fabricate and characterize novel <span class="hlt">porous</span> bioactive materials. 3D ordered macroporous bioactive glasses (3DOM-BGs, pore size: 200--1000 nm) were prepared using a sol-gel process and colloidal crystal templates. 3DOM-BGs are more bioactive and degradable than mesoporous (pore size <50 nm) sol-gel BGs in simulated body fluid (SBF). Apatite formation and 3DOM-BG degradation rates increased with the decrease of soaking ratio. Apatite induction time in SBF increased with 3DOM-BG calcination temperature (600--800°C). Apatite formation and 3DOMBG degradation were slightly enhanced for a phosphate containing composition. Large 3DOM-BG particles formed less apatite and degraded less completely as compared with small particles. An increase in macropore size slowed down 3DOM-BG degradation and apatite formation processes. After heating the converted apatite at a temperature higher than 700°C, highly crystalline hydroxyapatite and a minor tri-calcium phosphate phase formed. 3DOM-BGs have potential applications as bone/periodontal fillers, and drugs and biological factors delivery agents. Anchoring artificial soft tissues (e.g., cartilage) to native bone presents a challenge. <span class="hlt">Porous</span> polymer/bioactive glass composites are candidate materials for engineering artificial soft tissue/bone interfaces. <span class="hlt">Porous</span> composites consisting of polymer matrices (e.g., polysulfone, polylactide, and polyurethane) and bioactive glass particles were prepared by polymer phase separation techniques adapted to include ceramic particles. Composites (thickness: 200--500 mum) have asymmetric structures with dense top layers and <span class="hlt">porous</span> structures beneath. <span class="hlt">Porous</span> structures consist of large pores (>100 mum) in a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA05671&hterms=Tailings&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DTailings','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA05671&hterms=Tailings&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DTailings"><span>Bounce <span class="hlt">Rock</span> Dimple</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>This panoramic camera image shows the hole drilled by the Mars Exploration Rover Opportunity's <span class="hlt">rock</span> abrasion tool into the <span class="hlt">rock</span> dubbed 'Bounce' on Sol 65 of the rover's journey. The tool drilled about 7 millimeters (0.3 inches) into the <span class="hlt">rock</span> and generated small piles of 'tailings' or <span class="hlt">rock</span> dust around the central hole, which is about 4.5 centimeters (1.7 inches) across. The image from sol 66 of the mission was acquired using the panoramic camera's 430 nanometer filter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6438210','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6438210"><span>Opaque <span class="hlt">rock</span> fragments</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Abhijit, B.; Molinaroli, E.; Olsen, J.</p> <p>1987-05-01</p> <p>The authors describe a new, rare, but petrogenetically significant variety of <span class="hlt">rock</span> fragments from Holocene detrital sediments. Approximately 50% of the opaque heavy mineral concentrates from Holocene siliciclastic sands are polymineralic-Fe-Ti oxide particles, i.e., they are opaque <span class="hlt">rock</span> fragments. About 40% to 70% of these <span class="hlt">rock</span> fragments show intergrowth of hm + il, mt + il, and mt + hm +/- il. Modal analysis of 23,282 opaque particles in 117 polished thin sections of granitic and metamorphic parent <span class="hlt">rocks</span> and their daughter sands from semi-arid and humid climates show the following relative abundances. The data show that opaque <span class="hlt">rock</span> fragments are more common in sands from igneous source <span class="hlt">rocks</span> and that hm + il fragments are more durable. They assume that equilibrium conditions existed in parent <span class="hlt">rocks</span> during the growth of these paired minerals, and that the Ti/Fe ratio did not change during oxidation of mt to hm. Geothermometric determinations using electron probe microanalysis of opaque <span class="hlt">rock</span> fragments in sand samples from Lake Erie and the Adriatic Sea suggest that these <span class="hlt">rock</span> fragments may have equilibrated at approximately 900/sup 0/ and 525/sup 0/C, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA05671&hterms=tailing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dtailing','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA05671&hterms=tailing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dtailing"><span>Bounce <span class="hlt">Rock</span> Dimple</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>This panoramic camera image shows the hole drilled by the Mars Exploration Rover Opportunity's <span class="hlt">rock</span> abrasion tool into the <span class="hlt">rock</span> dubbed 'Bounce' on Sol 65 of the rover's journey. The tool drilled about 7 millimeters (0.3 inches) into the <span class="hlt">rock</span> and generated small piles of 'tailings' or <span class="hlt">rock</span> dust around the central hole, which is about 4.5 centimeters (1.7 inches) across. The image from sol 66 of the mission was acquired using the panoramic camera's 430 nanometer filter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA05103&hterms=Football&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DFootball','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA05103&hterms=Football&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DFootball"><span>Hungry for <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>This image from the Mars Exploration Rover Spirit hazard identification camera shows the rover's perspective just before its first post-egress drive on Mars. On Sunday, the 15th martian day, or sol, of Spirit's journey, engineers drove Spirit approximately 3 meters (10 feet) toward its first <span class="hlt">rock</span> target, a football-sized, mountain-shaped <span class="hlt">rock</span> called Adirondack (not pictured). In the foreground of this image are 'Sashimi' and 'Sushi' - two <span class="hlt">rocks</span> that scientists considered investigating first. Ultimately, these <span class="hlt">rocks</span> were not chosen because their rough and dusty surfaces are ill-suited for grinding.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005JPCM...17S.503M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005JPCM...17S.503M"><span>Fluids in <span class="hlt">porous</span> media: a morphometric approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mecke, Klaus; Arns, C. H.</p> <p>2005-03-01</p> <p>Predicting the relationship between the morphology of <span class="hlt">porous</span> media and their physical properties, e.g, the conductivity, elasticity and permeability, is a long-standing problem and important to a range of applications from geophysics to materials science. Here, a set of four morphological measures, so-called Minkowski functionals, is defined which allows one to quantitatively characterize the shape of spatial structures, to optimally reconstruct <span class="hlt">porous</span> media, and to accurately predict material properties. The method is based on integral geometry and Kac's theorem which relates the spectrum of the Laplace operator to the four Minkowski functionals. Analytic expressions for mean values of Minkowski functionals in Boolean models allow the definition of an effective shape of a grain in a system made up of a distribution of arbitrarily shaped constituents. Reconstructing the microstructure using this effective grain shape leads to an excellent match to the percolation thresholds and to the mechanical and transport properties across all phase fractions. Additionally, the use of the effective shape in effective medium formulations leads to good explicit predictions of bulk moduli. The method is verified for several model systems and sedimentary <span class="hlt">rock</span> samples, demonstrating that a single tomographic image is sufficient to estimate the morphology and physical properties such as permeabilities and elastic moduli for a range of porosities. Also the thermodynamic behaviour of fluids in <span class="hlt">porous</span> media, i.e., the shape dependence of the grand canonical potential and of surface energies of a fluid bounded by an arbitrarily shaped convex pore, can be calculated in the thermodynamic limit fully from the knowledge of the Minkowski functionals, i.e., of only four morphometric measures. This remarkable result is based on Hadwiger's theorem on the completeness of the additive Minkowski functionals and the assumption that a thermodynamic potential is an 'additive' functional which can be</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5510170','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5510170"><span>Graded/Gradient <span class="hlt">Porous</span> Biomaterials</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Miao, Xigeng; Sun, Dan</p> <p>2009-01-01</p> <p>Biomaterials include bioceramics, biometals, biopolymers and biocomposites and they play important roles in the replacement and regeneration of human tissues. However, dense bioceramics and dense biometals pose the problem of stress shielding due to their high Young’s moduli compared to those of bones. On the other hand, <span class="hlt">porous</span> biomaterials exhibit the potential of bone ingrowth, which will depend on <span class="hlt">porous</span> parameters such as pore size, pore interconnectivity, and porosity. Unfortunately, a highly <span class="hlt">porous</span> biomaterial results in poor mechanical properties. To optimise the mechanical and the biological properties, <span class="hlt">porous</span> biomaterials with graded/gradient porosity, pores size, and/or composition have been developed. Graded/gradient <span class="hlt">porous</span> biomaterials have many advantages over graded/gradient dense biomaterials and uniform or homogenous <span class="hlt">porous</span> biomaterials. The internal pore surfaces of graded/gradient <span class="hlt">porous</span> biomaterials can be modified with organic, inorganic, or biological coatings and the internal pores themselves can also be filled with biocompatible and biodegradable materials or living cells. However, graded/gradient <span class="hlt">porous</span> biomaterials are generally more difficult to fabricate than uniform or homogenous <span class="hlt">porous</span> biomaterials. With the development of cost-effective processing techniques, graded/gradient <span class="hlt">porous</span> biomaterials can find wide applications in bone defect filling, implant fixation, bone replacement, drug delivery, and tissue engineering.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/9328','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/9328"><span>Experimental and Theoretical Investigation of Multiphase Flow in Fractured <span class="hlt">Porous</span> media, SUPRI TR-116, Topical Report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Akin, Serhat; Castanier, Louis M.; German, Edgar Rene Rangel</p> <p>1999-08-09</p> <p>The fluid transfer parameters between <span class="hlt">rock</span> matrix and fracture are not well known. Consequently, simulation of fractured reservoirs uses, in general, very crude and unproven hypotheses such as zero capillary pressure in the fracture and/or relative permeability linear with saturation. In order to improve the understanding of flow in fractured media, an experimental study was conducted and numerical simulations of the experiments were made. A laboratory flow apparatus was built to obtain data on water- air imbibition and oil-water drainage displacements in horizontal single-fractured block systems. For this purpose, two configurations have been used: a two-block system with a 1 mm spacer between the blocks, and a two-block system with no spacer. During the experiments, porosity and saturation measurements along the cores have been made utilizing an X-ray Computerized Tomography (CT) scanner. Saturation images were reconstructed in 3-D to observe matrix-fracture interactions. Differences in <span class="hlt">fluid</span> <span class="hlt">saturations</span> and relative permeabilities caused by changes in fracture width have also been analyzed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7008502','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/7008502"><span><span class="hlt">Porous</span> electrode preparation method</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Arons, R.M.; Dusek, J.T.</p> <p>1983-10-18</p> <p>A <span class="hlt">porous</span> sintered plaque is provided with a bimodal porosity that is especially well suited for use as an electrode within a molten carbonate fuel cell. The coarse porosity is sufficient for admitting gases into contact with the reaction surfaces while the fine porosity is wetted with and retains molten electrolyte on the reaction sites. The electrode structure is prepared by providing a very fine powder of such as nickel oxide and blending the powder with a suitable decomposable binder to form a solid mass. The mass is comminuted into agglomerate size particles substantially larger than the fine oxide particles and formed into a cohesive compact for subsequent sintering. Sintering is carried out at sufficient conditions to bind the agglomerates together into a <span class="hlt">porous</span> structure having both coarse and fine porosity. Where lithiated nickel oxide cathodes are prepared, the sintering conditions can be moderate enough to retain substantial quantities of lithium within the electrode for adequate conductivity. 2 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/864745','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/864745"><span><span class="hlt">Porous</span> electrode preparation method</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Arons, Richard M.; Dusek, Joseph T.</p> <p>1983-01-01</p> <p>A <span class="hlt">porous</span> sintered plaque is provided with a bimodal porosity that is especially well suited for use as an electrode within a molten carbonate fuel cell. The coarse porosity is sufficient for admitting gases into contact with the reaction surfaces while the fine porosity is wetted with and retains molten electrolyte on the reaction sites. The electrode structure is prepared by providing a very fine powder of such as nickel oxide and blending the powder with a suitable decomposable binder to form a solid mass. The mass is comminuted into agglomerate size particles substantially larger than the fine oxide particles and formed into a cohesive compact for subsequent sintering. Sintering is carried out at sufficient conditions to bind the agglomerates together into a <span class="hlt">porous</span> structure having both coarse and fine porosity. Where lithiated nickel oxide cathodes are prepared, the sintering conditions can be moderate enough to retain substantial quantities of lithium within the electrode for adequate conductivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100011118','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100011118"><span>Strong, Lightweight, <span class="hlt">Porous</span> Materials</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Leventis, Nicholas; Meador, Mary Ann B.; Johnston, James C.; Fabrizio, Eve F.; Ilhan, Ulvi</p> <p>2007-01-01</p> <p>A new class of strong, lightweight, <span class="hlt">porous</span> materials has been invented as an outgrowth of an effort to develop reinforced silica aerogels. The new material, called X-Aerogel is less hygroscopic, but no less <span class="hlt">porous</span> and of similar density to the corresponding unmodified aerogels. However, the property that sets X-Aerogels apart is their mechanical strength, which can be as much as two and a half orders of magnitude stronger that the unmodified aerogels. X-Aerogels are envisioned to be useful for making extremely lightweight, thermally insulating, structural components, but they may also have applications as electrical insulators, components of laminates, catalyst supports, templates for electrode materials, fuel-cell components, and filter membranes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/874843','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/874843"><span><span class="hlt">Porous</span> polymer media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Shepodd, Timothy J.</p> <p>2002-01-01</p> <p>Highly crosslinked monolithic <span class="hlt">porous</span> polymer materials for chromatographic applications. By using solvent compositions that provide not only for polymerization of acrylate monomers in such a fashion that a <span class="hlt">porous</span> polymer network is formed prior to phase separation but also for exchanging the polymerization solvent for a running buffer using electroosmotic flow, the need for high pressure purging is eliminated. The polymer materials have been shown to be an effective capillary electrochromatographic separations medium at lower field strengths than conventional polymer media. Further, because of their highly crosslinked nature these polymer materials are structurally stable in a wide range of organic and aqueous solvents and over a pH range of 2-12.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/40203667','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/40203667"><span>Capillary Condensation in a Fractal <span class="hlt">Porous</span> Medium</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Broseta, Daniel; Barre, Loic; Vizika, Olga; Shahidzadeh, Noushine; Guilbaud, Jean-Pierre; Lyonnard, Sandrine</p> <p>2001-06-04</p> <p>Small-angle x-ray and neutron scattering are used to characterize the surface roughness and porosity of a natural <span class="hlt">rock</span> which are described over three decades in length scales and over nine decades in scattered intensities by a surface fractal dimension D=2.68{+-}0.03 . When this <span class="hlt">porous</span> medium is exposed to a vapor of a contrast-matched water, neutron scattering reveals that surface roughness disappears at small scales, where a Porod behavior typical of smooth interfaces is observed instead. Water-sorption measurements confirm that such interface smoothing is due predominantly to the water condensing in the most strongly curved asperities rather than covering the surface with a wetting film of uniform thickness.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22938317','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22938317"><span>Core-flood experiment for transport of reactive fluids in <span class="hlt">rocks</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ott, H; de Kloe, K; van Bakel, M; Vos, F; van Pelt, A; Legerstee, P; Bauer, A; Eide, K; van der Linden, A; Berg, S; Makurat, A</p> <p>2012-08-01</p> <p>Investigation of the transport of reactive fluids in <span class="hlt">porous</span> <span class="hlt">rocks</span> is an intriguing but challenging task and relevant in several areas of science and engineering such as geology, hydrogeology, and petroleum engineering. We designed and constructed an experimental setup to investigate physical and chemical processes caused by the flow of reactive and volatile fluids such as supercritical CO(2) and/or H(2)S in geological formations. Potential applications are geological sequestration of CO(2) in the frame of carbon capture and storage and acid-gas injection for sulfur disposal and/or enhanced oil recovery. The present paper outlines the design criteria and the realization of reactive transport experiments on the laboratory scale. We focus on the spatial and time evolution of <span class="hlt">rock</span> and fluid composition as a result of chemical <span class="hlt">rock</span> fluid interaction and the coupling of chemistry and fluid flow in <span class="hlt">porous</span> <span class="hlt">rocks</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5448587','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5448587"><span>Electrochemically Formed <span class="hlt">Porous</span> Silica</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Chazalviel, Jean-Noël; Ozanam, François</p> <p>2011-01-01</p> <p>Controlled electrochemical formation of <span class="hlt">porous</span> silica can be realized in dilute aqueous, neutral-pH, fluoride medium. Formation of a <span class="hlt">porous</span> film is initiated by sweeping the potential applied to silicon to values higher than 20 V. Film formation, reaching a steady state, may be pursued in a wide range of potentials, including lower potentials. The origin of a threshold potential for <span class="hlt">porous</span> film initiation has been explained quantitatively. All of the films appear mesoporous. Films grown at high potentials exhibit a variety of macrostructures superimposed on the mesoporosity. These macrostructures result from selective dissolution of silica induced by local pH lowering due to oxygen evolution. Films grown at potentials lower than 15 V appear uniform on the micrometer scale. However, all of the films also exhibit a stratified structure on the scale of a few tens of nanometres. This periodic structure can be traced back to the oscillatory behavior observed during the electrochemical dissolution of silicon in fluoride medium. It suggests that periodic breaking of the growing film may be responsible for this morphology. PMID:28879953</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/964283','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/964283"><span>2008 Gordon Research Conference on <span class="hlt">Rock</span> Deformation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hirth, James G.; Gray, Nancy Ryan</p> <p>2009-09-21</p> <p>The GRC on <span class="hlt">Rock</span> Deformation highlights the latest research in brittle and ductile <span class="hlt">rock</span> mechanics from experimental, field and theoretical perspectives. The conference promotes a multi-disciplinary forum for assessing our understanding of <span class="hlt">rock</span> strength and related physical properties in the Earth. The theme for the 2008 conference is 'Real-time Rheology'. Using ever-improving geophysical techniques, our ability to constrain the rheological behavior during earthquakes and post-seismic creep has improved significantly. Such data are used to investigate the frictional behavior of faults, processes responsible for strain localization, the viscosity of the lower crust, and viscous coupling between the crust and mantle. Seismological data also provide information on the rheology of the lower crust and mantle through analysis of seismic attenuation and anisotropy. Geologists are improving our understanding of rheology by combining novel analyses of microstructures in naturally deformed <span class="hlt">rocks</span> with petrologic data. This conference will bring together experts and students in these research areas with experimentalists and theoreticians studying the same processes. We will discuss and assess where agreement exists on rheological constraints derived at different length/time scales using different techniques - and where new insight is required. To encompass the elements of these topics, speakers and discussion leaders with backgrounds in geodesy, experimental <span class="hlt">rock</span> deformation, structural geology, earthquake seismology, geodynamics, glaciology, materials science, and mineral physics will be invited to the conference. Thematic sessions will be organized on the dynamics of earthquake rupture, the rheology of the lower crust and coupling with the upper mantle, the measurement and interpretation of seismic attenuation and anisotropy, the dynamics of ice sheets and the coupling of reactive <span class="hlt">porous</span> flow and brittle deformation for understanding geothermal and chemical properties of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10185682','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10185682"><span>The <span class="hlt">rock</span> melting approach to drilling</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cort, G.E.; Goff, S.J.; Rowley, J.C.; Neudecker, J.W. Jr.; Dreesen, D.S.; Winchester, W.</p> <p>1993-09-01</p> <p>During the early and mid-1970`s the Los Alamos National Laboratory demonstrated practical applications of drilling and coring using an electrically-heated graphite, tungsten, or molybdenum penetrator that melts a hole as it is slowly pushed through the <span class="hlt">rock</span> or soil. The molten material consolidates into a rugged glass lining that prevents hole collapse; minimizes the potential for cross-flow, lost circulation, or the release of hazardous materials without casing operations; and produces no cuttings in <span class="hlt">porous</span> or low density (<1.7 g/cc) formations. Because there are no drilling fluids required, the <span class="hlt">rock</span> melting approach reduces waste handling, treatment and disposal. Drilling by <span class="hlt">rock</span> melting has been demonstrated to depths up to 30 m in caliche, clay, alluvium, cobbles, sand, basalt, granite, and other materials. Penetrating large cobbles without debris removal was achieved by thermal stress fracturing and lateral extrusion of portions of the <span class="hlt">rock</span> melt into the resulting cracks. Both horizontal and vertical holes in a variety of diameters were drilled in these materials using modular, self-contained field units that operate in remote areas. Because the penetrator does not need to rotate, steering by several simple approaches is considered quite feasible. Melting is ideal for obtaining core samples in alluvium and other poorly consolidated soils since the formed-in-place glass liner stabilizes the hole, encapsulates volatile or hazardous material, and recovers an undisturbed core. Because of the relatively low thermal conductivity of <span class="hlt">rock</span> and soil materials, the heat-affected zone beyond the melt layer is very small, <1 inch thick. Los Alamos has begun to update the technology and this paper will report on the current status of applications and designs for improved drills.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMMR52A..03P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMMR52A..03P"><span>Flow and Fracture in Deformable <span class="hlt">Porous</span> Media: a Magmatic Perspective</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Petford, N.</p> <p>2012-12-01</p> <p>This contribution reviews some recent advances in the flow and fracture of deformable <span class="hlt">porous</span> media with implications for melt extraction in the lower crust and upper mantle. A long standing issue concerning extraction of partial melt from hot, high pressure regions (that is, most of the earth's solid interior) is the apparent contradiction that fracturing can occur in highly compliant material. I argue that much of the source of conflict surrounding the idea of 'fracture' in ductile/plastic <span class="hlt">rock</span> is due to lack of clarity of terminology combined with conceptual notions equating fracture as defined in brittle <span class="hlt">rock</span> through the theory of linear elasticity (a process well understood), with deformation and failure in weakly consolidated <span class="hlt">rock</span>. So, while the former is based fundamentally on stress singularities and strain energy processes at a propagating fracture tip, continuum models of fracture in granular media struggle to define precisely the discontinuous nature of the physics involved. Thus, for fracture in <span class="hlt">porous</span> media (and here an equivalence is made with igneous <span class="hlt">porous</span> media, that is, a silicate melt phase plus skeletal, granular matrix), verbs like parting, dilation and seepage in response to fluid (melt) pressurised translation of a weakly bonded matrix become the equivalent of cracks/veins/fractures in traditional (Griffiths) fracture mechanics. At its simplest, the process of fracturing in both classes of material can be defined by the difference in lengthscale and geometry of dissipated energy around the opening fracture. Treated in this way, controversies about the ability of weak/ductile <span class="hlt">rock</span> to 'fracture' become instead productive discussions on the relative roles of fluid pressure, flow rates and rheology in promoting localised deformation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-201303120005HQ.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-201303120005HQ.html"><span>Mars <span class="hlt">Rock</span> Analysis Briefing</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2013-03-12</p> <p>John Grotzinger (second from left), Curiosity project scientist, California Institute of Technology in Pasadena, speaks at a news conference presenting findings of the Curiosity rover's analysis of the first sample of <span class="hlt">rock</span> powder collected on Mars, Tuesday, March 12, 2013 in Washington. The <span class="hlt">rock</span> sample collected shows ancient Mars could have supported living microbes. Photo Credit: (NASA/Carla Cioffi)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-201303120008HQ.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-201303120008HQ.html"><span>Mars <span class="hlt">Rock</span> Analysis Briefing</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2013-03-12</p> <p>John Grotzinger, Curiosity project scientist, California Institute of Technology in Pasadena, answers a reporter's question at a news conference where findings of the Curiosity rover's analysis of the first sample of <span class="hlt">rock</span> powder collected on Mars were presented, Tuesday, March 12, 2013 in Washington. The <span class="hlt">rock</span> sample collected shows ancient Mars could have supported living microbes. Photo Credit: (NASA/Carla Cioffi)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-201303120004HQ.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-201303120004HQ.html"><span>Mars <span class="hlt">Rock</span> Analysis Briefing</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2013-03-12</p> <p>John Grotzinger (center), Curiosity project scientist, California Institute of Technology in Pasadena, speaks at a news conference presenting findings of the Curiosity rover's analysis of the first sample of <span class="hlt">rock</span> powder collected on Mars, Tuesday, March 12, 2013 in Washington. The <span class="hlt">rock</span> sample collected shows ancient Mars could have supported living microbes. Photo Credit: (NASA/Carla Cioffi)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/838242','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/838242"><span>Session: Hard <span class="hlt">Rock</span> Penetration</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tennyson, George P. Jr.; Dunn, James C.; Drumheller, Douglas S.; Glowka, David A.; Lysne, Peter</p> <p>1992-01-01</p> <p>This session at the Geothermal Energy Program Review X: Geothermal Energy and the Utility Market consisted of five presentations: ''Hard <span class="hlt">Rock</span> Penetration - Summary'' by George P. Tennyson, Jr.; ''Overview - Hard <span class="hlt">Rock</span> Penetration'' by James C. Dunn; ''An Overview of Acoustic Telemetry'' by Douglas S. Drumheller; ''Lost Circulation Technology Development Status'' by David A. Glowka; ''Downhole Memory-Logging Tools'' by Peter Lysne.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA05667&hterms=First+impressions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DFirst%2Bimpressions','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA05667&hterms=First+impressions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DFirst%2Bimpressions"><span><span class="hlt">Rock</span> Bites into 'Bounce'</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>This panoramic camera image from the Mars Exploration Rover Opportunity features the 6.44 millimeter (0.25 inch) deep hole ground into the <span class="hlt">rock</span> dubbed 'Bounce' by the rover's <span class="hlt">rock</span> abrasion tool. The tool took 2 hours and 15 minutes to grind the hole on sol 66 of the rover's journey. A combination of limited solar power and the <span class="hlt">rock</span>'s jagged texture led the <span class="hlt">rock</span> abrasion tool team to set very aggressive grinding parameters to ensure that the end result was a full circle, suitable for a thorough read from the rover's spectrometers. <p/> Bounce's markedly different appearance (when compared to the <span class="hlt">rocks</span> that were previously examined in the Eagle Crater outcrop) made it a natural target for rover research. In order to achieve an ideal position from which to grind into the <span class="hlt">rock</span>, Opportunity moved in very close with its right wheel next to Bounce. In this image, the panoramic camera on the rover's mast is looking down, catching the tip of the solar panel which partially blocks the full circle ground by the <span class="hlt">rock</span> abrasion tool. <p/> The outer ring consists of the cuttings from the <span class="hlt">rock</span>, pushed out by the brushes on the grinding instrument. The dark impression at the top of the outer circle was caused by the instrument's contact mechanism which serves to stabilize it while grinding.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA03862.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA03862.html"><span>Odyssey/White <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2002-10-01</p> <p>These Mars Odyssey images show the White <span class="hlt">Rock</span> feature on Mars in both infrared left and visible right wavelengths. White <span class="hlt">Rock</span> is the unofficial name for this landform that was first observed during NASA Mariner 9 mission in the early 1970.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=Rock+AND+Cycle&id=EJ620476','ERIC'); return false;" href="https://eric.ed.gov/?q=Rock+AND+Cycle&id=EJ620476"><span><span class="hlt">Rock</span> Cycle Roulette.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Schmidt, Stan M.; Palmer, Courtney</p> <p>2000-01-01</p> <p>Introduces an activity on the <span class="hlt">rock</span> cycle. Sets 11 stages representing the transitions of an earth material in the <span class="hlt">rock</span> cycle. Builds six-sided die for each station, and students move to the stations depending on the rolling side of the die. Evaluates students by discussing several questions in the classroom. Provides instructional information for…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=Igneous+AND+rocks&pg=2&id=EJ721556','ERIC'); return false;" href="https://eric.ed.gov/?q=Igneous+AND+rocks&pg=2&id=EJ721556"><span>Welcome to <span class="hlt">Rock</span> Day</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Varelas, Maria; Benhart, Jeaneen</p> <p>2004-01-01</p> <p>At the beginning of the school year, the authors, a first-grade teacher and a teacher educator, worked together to "spice up" the first-grade science curriculum. The teacher had taught the unit <span class="hlt">Rocks</span>, Sand, and Soil several times, conducting hands-on explorations and using books to help students learn about properties of <span class="hlt">rocks</span>, but she felt the…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=Sedimentary+AND+rocks&pg=2&id=EJ721556','ERIC'); return false;" href="http://eric.ed.gov/?q=Sedimentary+AND+rocks&pg=2&id=EJ721556"><span>Welcome to <span class="hlt">Rock</span> Day</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Varelas, Maria; Benhart, Jeaneen</p> <p>2004-01-01</p> <p>At the beginning of the school year, the authors, a first-grade teacher and a teacher educator, worked together to "spice up" the first-grade science curriculum. The teacher had taught the unit <span class="hlt">Rocks</span>, Sand, and Soil several times, conducting hands-on explorations and using books to help students learn about properties of <span class="hlt">rocks</span>, but she felt the…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-201303120002HQ.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-201303120002HQ.html"><span>Mars <span class="hlt">Rock</span> Analysis Briefing</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2013-03-12</p> <p>David Blake, principal investigator for Curiosity's Chemistry and Mineralogy investigation at NASA's Ames Research Center in Calif., speaks at a news conference presenting findings of the Curiosity rover's analysis of the first sample of <span class="hlt">rock</span> powder collected on Mars, Tuesday, March 12, 2013 in Washington. The <span class="hlt">rock</span> sample collected shows ancient Mars could have supported living microbes. Photo Credit: (NASA/Carla Cioffi)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA12452.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA12452.html"><span>Chocolate Hills <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2010-02-16</p> <p>This false-color image, taken by the panoramic camera on NASA rover Opportunity, shows the <span class="hlt">rock</span> Chocolate Hills, perched on the rim of the 10-meter 33-foot wide Concepcion crater. This <span class="hlt">rock</span> has a thick, dark-colored coating resembling chocolate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=Rock+AND+Cycle&id=EJ620476','ERIC'); return false;" href="http://eric.ed.gov/?q=Rock+AND+Cycle&id=EJ620476"><span><span class="hlt">Rock</span> Cycle Roulette.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Schmidt, Stan M.; Palmer, Courtney</p> <p>2000-01-01</p> <p>Introduces an activity on the <span class="hlt">rock</span> cycle. Sets 11 stages representing the transitions of an earth material in the <span class="hlt">rock</span> cycle. Builds six-sided die for each station, and students move to the stations depending on the rolling side of the die. Evaluates students by discussing several questions in the classroom. Provides instructional information for…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA05667&hterms=bite+block&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dbite%2Bblock','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA05667&hterms=bite+block&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dbite%2Bblock"><span><span class="hlt">Rock</span> Bites into 'Bounce'</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>This panoramic camera image from the Mars Exploration Rover Opportunity features the 6.44 millimeter (0.25 inch) deep hole ground into the <span class="hlt">rock</span> dubbed 'Bounce' by the rover's <span class="hlt">rock</span> abrasion tool. The tool took 2 hours and 15 minutes to grind the hole on sol 66 of the rover's journey. A combination of limited solar power and the <span class="hlt">rock</span>'s jagged texture led the <span class="hlt">rock</span> abrasion tool team to set very aggressive grinding parameters to ensure that the end result was a full circle, suitable for a thorough read from the rover's spectrometers. <p/> Bounce's markedly different appearance (when compared to the <span class="hlt">rocks</span> that were previously examined in the Eagle Crater outcrop) made it a natural target for rover research. In order to achieve an ideal position from which to grind into the <span class="hlt">rock</span>, Opportunity moved in very close with its right wheel next to Bounce. In this image, the panoramic camera on the rover's mast is looking down, catching the tip of the solar panel which partially blocks the full circle ground by the <span class="hlt">rock</span> abrasion tool. <p/> The outer ring consists of the cuttings from the <span class="hlt">rock</span>, pushed out by the brushes on the grinding instrument. The dark impression at the top of the outer circle was caused by the instrument's contact mechanism which serves to stabilize it while grinding.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA05678&hterms=Ferrous&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DFerrous','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA05678&hterms=Ferrous&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DFerrous"><span>Bounce <span class="hlt">Rock</span> Snapshot</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/> [figure removed for brevity, see original site] Figure 1 This Mars Exploration Rover Opportunity panoramic camera image shows 'Bounce <span class="hlt">Rock</span>,' a <span class="hlt">rock</span> the airbag-packaged rover struck while rolling to a stop on January 24, 2004. This is the largest <span class="hlt">rock</span> for as far as the eye can see, approximately 35 centimeters (14 inches) long and 10 centimeters (4 inches) high. There appears to be a dusty coating on the top of parts of the <span class="hlt">rock</span>, which may have been broken when it was struck by the airbags. The <span class="hlt">rock</span> was about 5 meters (16 feet) from the rover when this image was obtained. This is an enhanced color composite image from sol 36 of the rover's journey, generated using the camera's L2 (750 nanometer), L5 (530 nanometer), and L6 (480 nanometer) filters. <p/> <i>Bounce <span class="hlt">Rock</span> Spectra</i> Figure 1 above is a plot of panoramic camera spectra extracted from three different regions on the <span class="hlt">rock</span> dubbed 'Bounce.' The yellow spectrum is from the yellow box in the image on the left, from the dusty top part of the <span class="hlt">rock</span>. The spectrum is dominated by the signature of oxidized 'ferric' iron (Fe3+) like that seen in the classic Martian dust. The red spectrum is from the darker Meridiani Planum soils that were disturbed by the airbag when it bounced near the <span class="hlt">rock</span>. That spectrum is also dominated by ferric iron, though the reflectivity is lower. Scientists speculate that this may be because the grains are coarser in these soils compared to the dust. The green spectrum, which is from the right side of the <span class="hlt">rock</span>, shows a strong drop in the infrared reflectance that is unlike any other <span class="hlt">rock</span> yet seen at Meridiani Planum or Gusev Crater. This spectral signature is typical of un-oxidized 'ferrous' iron (Fe2+) in the <span class="hlt">rock</span>, perhaps related to the presence of volcanic minerals like olivine or pyroxene. The possibility that this may be a basaltic <span class="hlt">rock</span> that is distinctly different from the <span class="hlt">rocks</span> seen in the Eagle Crater outcrop is being intensively explored using the rover's other instruments.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA06323&hterms=Sedimentary+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DSedimentary%2Brocks','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA06323&hterms=Sedimentary+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DSedimentary%2Brocks"><span>Layered <span class="hlt">Rocks</span> in Crater</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/> 19 June 2004 Exposures of layered, sedimentary <span class="hlt">rock</span> are common on Mars. From the <span class="hlt">rock</span> outcrops examined by the Mars Exploration Rover, Opportunity, in Meridiani Planum to the sequence in Gale Crater's central mound that is twice the thickness of of the sedimentary <span class="hlt">rocks</span> exposed by Arizona's Grand Canyon, Mars presents a world of sediment to study. This unusual example, imaged by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC), shows eroded layer outcrops in a crater in Terra Tyrrhena near 15.4oS, 270.5oW. Sedimentary <span class="hlt">rocks</span> provide a record of past climates and events. Perhaps someday the story told by the <span class="hlt">rocks</span> in this image will be known via careful field work. The image covers an area about 3 km (1.9 mi) wide and is illuminated by sunlight from the left.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3600995','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3600995"><span><span class="hlt">Porous</span> microsphere and its applications</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cai, Yunpeng; Chen, Yinghui; Hong, Xiaoyun; Liu, Zhenguo; Yuan, Weien</p> <p>2013-01-01</p> <p><span class="hlt">Porous</span> microspheres have drawn great attention in the last two decades for their potential applications in many fields, such as carriers for drugs, absorption and desorption of substances, pulmonary drug delivery, and tissue regeneration. The application of <span class="hlt">porous</span> microspheres has become a feasible way to address existing problems. In this essay, we give a brief introduction of the <span class="hlt">porous</span> microsphere, its characteristics, preparation methods, applications, and a brief summary of existing problems and research tendencies. PMID:23515359</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28691065','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28691065"><span><span class="hlt">Porous</span> Molecular Solids and Liquids.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cooper, Andrew I</p> <p>2017-06-28</p> <p>Until recently, <span class="hlt">porous</span> molecular solids were isolated curiosities with properties that were eclipsed by <span class="hlt">porous</span> frameworks, such as metal-organic frameworks. Now molecules have emerged as a functional materials platform that can have high levels of porosity, good chemical stability, and, uniquely, solution processability. The lack of intermolecular bonding in these materials has also led to new, counterintuitive states of matter, such as <span class="hlt">porous</span> liquids. Our ability to design these materials has improved significantly due to advances in computational prediction methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA164883','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA164883"><span>Dynamic Compaction of <span class="hlt">Porous</span> Beds</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1985-12-26</p> <p>NSWVC TR 83-246 00 00 SDYNAMIC COMPACTION OF <span class="hlt">POROUS</span> B3EDS BY H. W. SANDUSKY T. P. LIDDIARD RESEARCH AND TECHNOLOGY DEPARTMENT D I 26 DECEMBER 1985...RIOBA4313 11. TITLE (Include Security Classfication3 Dynamic Compaction of <span class="hlt">Porous</span> Beds 12. PERSONAL AUTHOR(S) Sandusky, H. W., and Liddiard, T. P. 13a... <span class="hlt">Porous</span> Bed Compaction Wave Velocity Oeflaaration-to-Detonation Transition Particle Velocity ABSTRACT (Continue on reverse if necessary and identify</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADD018882','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADD018882"><span><span class="hlt">Porous</span> Materials by Powder Metallurgy</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1998-04-30</p> <p>generally determine porosity and pore size of the resulting <span class="hlt">porous</span> material. The beads can be microballoons, which are hollow inside, or they can be...proved jYi- --*;V--, - one QUALITY INSPECTED 0 Applicant: Everett Patent Application Serial Number: Navy Case Number: 78,529 5 <span class="hlt">Porous</span> Materials...By Powder Metallurgy Background of Invention Field of Invention: This invention pertains to <span class="hlt">porous</span> material fabrication by controlling pore size</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.H54F..03S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.H54F..03S"><span>Modeling the Impact of Fracture Growth on Fluid Displacements in Deformable <span class="hlt">Porous</span> Media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Santillán, D.; Cueto-Felgueroso, L.; Juanes, R.</p> <p>2015-12-01</p> <p>Coupled flow and geomechanics is a critical research challenge in engineering and the geosciences. The flow of a fluid through a deformable <span class="hlt">porous</span> media is present in manyenvironmental, industrial, and biological processes,such as the removal of pollutants from underground water bodies, enhanced geothermal systems, unconventional hydrocarbon resources or enhanced oil recovery techniques. However, the injection of a fluid can generate or propagate fractures, which are preferential flow paths. Using numerical simulation, we study the interplay between injection and <span class="hlt">rock</span> mechanics, and elucidate fracture propagation as a function of injection rate, initial crack topology and mechanical <span class="hlt">rock</span> properties. Finally, we discuss the role of fracture growth on fluid displacements in <span class="hlt">porous</span> media. Figure: An example of fracture (in red) propagated in a <span class="hlt">porous</span> media (in blue)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940011487','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940011487"><span>Selective formation of <span class="hlt">porous</span> silicon</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fathauer, Jones (Inventor)</p> <p>1993-01-01</p> <p>A pattern of <span class="hlt">porous</span> silicon is produced in the surface of a silicon substrate by forming a pattern of crystal defects in said surface, preferably by applying an ion milling beam through openings in a photoresist layer to the surface, and then exposing said surface to a stain etchant, such as HF:HNO3:H20. The defected crystal will preferentially etch to form a pattern of <span class="hlt">porous</span> silicon. When the amorphous content of the <span class="hlt">porous</span> silicon exceeds 70 percent, the <span class="hlt">porous</span> silicon pattern emits visible light at room temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960009264','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960009264"><span>Selective formation of <span class="hlt">porous</span> silicon</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fathauer, Robert W. (Inventor); Jones, Eric W. (Inventor)</p> <p>1993-01-01</p> <p>A pattern of <span class="hlt">porous</span> silicon is produced in the surface of a silicon substrate by forming a pattern of crystal defects in said surface, preferably by applying an ion milling beam through openings in a photoresist layer to the surface, and then exposing said surface to a stain etchant, such as HF:HNO3:H2O. The defected crystal will preferentially etch to form a pattern of <span class="hlt">porous</span> silicon. When the amorphous content of the <span class="hlt">porous</span> silicon exceeds 70 percent, the <span class="hlt">porous</span> silicon pattern emits visible light at room temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009IJEaS..98..227T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009IJEaS..98..227T"><span>Life inhabits <span class="hlt">rocks</span>: clues to <span class="hlt">rock</span> erosion from electron microscopy of pisolite at a UNESCO heritage site in Brazil</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tazaki, Kazue; Asada, Ryuji; Lindenmayer, Zara Gerhardt; Shirotori, Tatsuya; Vargas, Juliana Missiaggia; Nowatzki, Carlos Henrique; Coelho, Osmar Wöhl</p> <p>2009-02-01</p> <p><span class="hlt">Rock</span> erosion is attracting increasing attention from scientists worldwide. The area encompassing the Saint John Baptist Church, Saint John Village, XVII century ruins in Rio Grande do Sul at the UNESCO World Heritage Site is considered a Brazilian treasure. However, the risk of damage to this site from <span class="hlt">rock</span> erosion has recently increased tremendously. Generally, the rocky construction such as fence, wall and tomb stone, seems strong but is actually extremely sensitive to erosion caused by lichens, fungi, molds and bacteria. Because of biological erosion and massive exposure, the fresh <span class="hlt">rock</span> is dominated by clays and microorganisms. Water-adsorbing clays and microorganisms influence the mechanisms of the <span class="hlt">rock</span> erosion. In this study, the formation of bio-clay-minerals in <span class="hlt">porous</span> structure of pisolite was demonstrated using electron microscopy. Bacterial clay mineralization can deform the <span class="hlt">rock</span> structure and even produce organic materials. Biological activity could easily corrode rocky constructions around the Saint John Baptist Church site. The <span class="hlt">rocks</span> are pisolitic laterites possibly formed in Tertiary over the Kretaceous Parana flood Basalts. Samples inhabited by lichens and fungi were collected from a collapsed wall in the ancient church. The zonal reddish-brown pisolites are 4 mm in diameter in a matrix of clays associated with <span class="hlt">porous</span> and empty spaces. Elemental distribution maps from X-ray fluorescence microscopy show iron-rich spherules of pisolite, whereas the matrix is composed of Al, Si, Mn, and Sr; thus producing goethite and kaolinite. Transmission electron microscopic observation showed that various types of bacteria inhabit the spherule and are associated with clay minerals and graphite. STEM elemental analysis confirmed the bio-clay-mineralization with Al, Si, S, and Fe, around bacterial cells. The results presented here will improve our understanding of nm-scale bio-mineralization and bio-erosion in lateritic <span class="hlt">rocks</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28622466','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28622466"><span>Dissolved CO2 Increases Breakthrough Porosity in Natural <span class="hlt">Porous</span> Materials.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Y; Bruns, S; Stipp, S L S; Sørensen, H O</p> <p>2017-07-18</p> <p>When reactive fluids flow through a dissolving <span class="hlt">porous</span> medium, conductive channels form, leading to fluid breakthrough. This phenomenon is caused by the reactive infiltration instability and is important in geologic carbon storage where the dissolution of CO2 in flowing water increases fluid acidity. Using numerical simulations with high resolution digital models of North Sea chalk, we show that the breakthrough porosity is an important indicator of dissolution pattern. Dissolution patterns reflect the balance between the demand and supply of cumulative surface. The demand is determined by the reactive fluid composition while the supply relies on the flow field and the <span class="hlt">rock</span>'s microstructure. We tested three model scenarios and found that aqueous CO2 dissolves <span class="hlt">porous</span> media homogeneously, leading to large breakthrough porosity. In contrast, solutions without CO2 develop elongated convective channels known as wormholes, with low breakthrough porosity. These different patterns are explained by the different apparent solubility of calcite in free drift systems. Our results indicate that CO2 increases the reactive subvolume of <span class="hlt">porous</span> media and reduces the amount of solid residual before reactive fluid can be fully channelized. Consequently, dissolved CO2 may enhance contaminant mobilization near injection wellbores, undermine the mechanical sustainability of formation <span class="hlt">rocks</span> and increase the likelihood of buoyance driven leakage through carbonate rich caprocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.youtube.com/watch?v=imSrbp3cYcU','SCIGOVIMAGE-NASA'); return false;" href="http://www.youtube.com/watch?v=imSrbp3cYcU"><span>Our World: The <span class="hlt">Rock</span> Cycle</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p></p> <p>Find out how <span class="hlt">rocks</span> brought to Earth by the Apollo astronauts have helped NASA learn more about the <span class="hlt">rock</span> cycle. Compare igneous, sedimentary and metamorphic <span class="hlt">rocks</span> found on Earth to three types of ro...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017E%26PSL.457...38B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E%26PSL.457...38B"><span>Pore geometry as a control on <span class="hlt">rock</span> strength</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bubeck, A.; Walker, R. J.; Healy, D.; Dobbs, M.; Holwell, D. A.</p> <p>2017-01-01</p> <p>The strength of <span class="hlt">rocks</span> in the subsurface is critically important across the geosciences, with implications for fluid flow, mineralisation, seismicity, and the deep biosphere. Most studies of <span class="hlt">porous</span> <span class="hlt">rock</span> strength consider the scalar quantity of porosity, in which strength shows a broadly inverse relationship with total porosity, but pore shape is not explicitly defined. Here we use a combination of uniaxial compressive strength measurements of isotropic and anisotropic <span class="hlt">porous</span> lava samples, and numerical modelling to consider the influence of pore shape on <span class="hlt">rock</span> strength. Micro computed tomography (CT) shows that pores range from sub-spherical to elongate and flat ellipsoids. Samples that contain flat pores are weaker if compression is applied parallel to the short axis (i.e. across the minimum curvature), compared to compression applied parallel to the long axis (i.e. across the maximum curvature). Numerical models for elliptical pores show that compression applied across the minimum curvature results in relatively broad amplification of stress, compared to compression applied across the maximum curvature. Certain pore shapes may be relatively stable and remain open in the upper crust under a given remote stress field, while others are inherently weak. Quantifying the shape, orientations, and statistical distributions of pores is therefore a critical step in strength testing of <span class="hlt">rocks</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.9543D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9543D"><span>Characterizing and modelling 'ghost-<span class="hlt">rock</span>' weathered limestones</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dubois, Caroline; Goderniaux, Pascal; Deceuster, John; Poulain, Angélique; Kaufmann, Olivier</p> <p>2016-04-01</p> <p>'Ghost-<span class="hlt">rock</span>' karst aquifer has recently been highlighted. In this particular type of aquifer, the karst is not expressed as open conduits but consists in zones where the limestone is weathered. The in-situ weathering of limestone leaves a soft <span class="hlt">porous</span> material called 'alterite'. The hydro-mechanical properties of this material differs significantly from those of the host <span class="hlt">rock</span>: the weathering enhances the storage capacity and the conductivity of the <span class="hlt">rock</span>. This type of weathered karst aquifer has never been studied from a hydrogeological point of view. In this study, we present the hydraulic characterization of such weathered zones. We also present a modelling approach derived from the common Equivalent <span class="hlt">Porous</span> Medium (EPM) approach, but including the spatial distribution of hydrogeological properties through the weathered features, from the hard <span class="hlt">rock</span> to the alterite, according to a weathering index. Unlike the Discrete Fracture Network (DFN) approaches, which enable to take into account a limited number of fractures, this new approach allows creating models including thousands of weathered features. As the properties of the alterite have to be considered at a centimeter scale, it is necessary to upscale these properties to carry out simulations over large areas. Therefore, an upscaling method was developed, taking into account the anisotropy of the weathered features. Synthetic models are built, upscaled and different hydrogeological simulations are run to validate the method. This methodology is finally tested on a real case study: the modelling of the dewatering drainage flow of an exploited quarry in a weathered karst aquifer in Belgium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18..555R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18..555R"><span>Experimental Study of Shale <span class="hlt">Rock</span> Self-Heating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Restuccia, Francesco; Ptak, Nicolas; Rein, Guillermo</p> <p>2016-04-01</p> <p>Self-heating phenomena due to spontaneous exothermic reactions in oxidative environments are common for many <span class="hlt">porous</span> materials, even at low temperatures. Combustion of shale outcrop formations has been reported in recent years, with self-heating a potential initiating cause. This work studies experimentally and for the first time the self-heating behavior of shale <span class="hlt">rock</span>, a <span class="hlt">porous</span> sedimentary <span class="hlt">rock</span>. Using field samples collected from shale outcrop at Kimmeridge Bay (UK) and the Frank-Kamenetskii theory of criticality, we determine effective kinetic parameters and thermal properties for different shale particle size distributions and upscale the results to field formations of different thicknesses. We show that for fine particle sizes, with diameter below 2mm, spontaneous ignition is possible for <span class="hlt">rock</span> formations of thickness between 25m and 5.4m at ambient temperatures between 16°C and 44°C. For the same temperature range, the required thickness is between 375km and 15km for coarse particles of diameter below 17mm. This shows that shale <span class="hlt">rock</span> is reactive, with reactivity highly dependent on particle diameter, and self-ignition is possible for small particles in outcrops or formations accidentally exposed to oxygen.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110023320','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110023320"><span>Space Weathering of <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Noble, Sarah</p> <p>2011-01-01</p> <p>Space weathering discussions have generally centered around soils but exposed <span class="hlt">rocks</span> will also incur the effects of weathering. On the Moon, <span class="hlt">rocks</span> make up only a very small percentage of the exposed surface and areas where <span class="hlt">rocks</span> are exposed, like central peaks, are often among the least space weathered regions we find in remote sensing data. However, our studies of weathered Ap 17 <span class="hlt">rocks</span> 76015 and 76237 show that significant amounts of weathering products can build up on <span class="hlt">rock</span> surfaces. Because <span class="hlt">rocks</span> have much longer surface lifetimes than an individual soil grain, and thus record a longer history of exposure, we can study these products to gain a deeper perspective on the weathering process and better assess the relative impo!1ance of various weathering components on the Moon. In contrast to the lunar case, on small asteroids, like Itokowa, <span class="hlt">rocks</span> make up a large fraction of the exposed surface. Results from the Hayabusa spacecraft at Itokowa suggest that while the low gravity does not allow for the development of a mature regolith, weathering patinas can and do develop on <span class="hlt">rock</span> surfaces, in fact, the rocky surfaces were seen to be darker and appear spectrally more weathered than regions with finer materials. To explore how weathering of asteroidal <span class="hlt">rocks</span> may differ from lunar, a set of ordinary chondrite meteorites (H, L, and LL) which have been subjected to artificial space weathering by nanopulse laser were examined by TEM. NpFe(sup 0) bearing glasses were ubiquitous in both the naturally-weathered lunar and the artificially-weathered meteorite samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1916529L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1916529L"><span>Self-similar evolution of stress distributions in a <span class="hlt">porous</span> limestone under dissolution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Linga, Gaute; Mathiesen, Joachim; Renard, Francois</p> <p>2017-04-01</p> <p>The heterogeneous spatial distribution of pore space within a <span class="hlt">porous</span> <span class="hlt">rock</span> leads to a strong heterogeneity in fluid flow rates and in the stress distribution in the <span class="hlt">rock</span> mass. In this work, we consider a limestone sample that has undergone several steps of dissolution, which at each step has been scanned by 3D X-ray tomography. We calculate numerically at each step the coupled system of steady-state fluid flow in the pore space and elasticity in the solid. We quantify by using probability density functions (PDFs) the effect of the fluid flow field upon the stress distribution both at the pore wall surface and in the solid <span class="hlt">rock</span> matrix. We find that, during dissolution, the distributions of stress evolve in a self-similar manner as the porosity is increased. Moreover, the PDFs display heavy tails towards large stresses. The common master curves offer a unified description of the stress for a <span class="hlt">rock</span> with evolving microstructure, and if the results can be generalized to other <span class="hlt">porous</span> media, they may provide an additional explanation of the sensitivity to failure of <span class="hlt">porous</span> <span class="hlt">rocks</span> under small changes of stress.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...632393Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...632393Z"><span>Study of Gas Flow Characteristics in Tight <span class="hlt">Porous</span> Media with a Microscale Lattice Boltzmann Model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, Jianlin; Yao, Jun; Zhang, Min; Zhang, Lei; Yang, Yongfei; Sun, Hai; An, Senyou; Li, Aifen</p> <p>2016-09-01</p> <p>To investigate the gas flow characteristics in tight <span class="hlt">porous</span> media, a microscale lattice Boltzmann (LB) model with the regularization procedure is firstly adopted to simulate gas flow in three-dimensional (3D) digital <span class="hlt">rocks</span>. A shale digital <span class="hlt">rock</span> and a sandstone digital <span class="hlt">rock</span> are reconstructed to study the effects of pressure, temperature and pore size on microscale gas flow. The simulation results show that because of the microscale effect in tight <span class="hlt">porous</span> media, the apparent permeability is always higher than the intrinsic permeability, and with the decrease of pressure or pore size, or with the increase of temperature, the difference between apparent permeability and intrinsic permeability increases. In addition, the Knudsen numbers under different conditions are calculated and the results show that gas flow characteristics in the digital <span class="hlt">rocks</span> under different Knudsen numbers are quite different. With the increase of Knudsen number, gas flow in the digital <span class="hlt">rocks</span> becomes more uniform and the effect of heterogeneity of the <span class="hlt">porous</span> media on gas flow decreases. Finally, two commonly used apparent permeability calculation models are evaluated by the simulation results and the Klinkenberg model shows better accuracy. In addition, a better proportionality factor in Klinkenberg model is proposed according to the simulation results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5009359','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5009359"><span>Study of Gas Flow Characteristics in Tight <span class="hlt">Porous</span> Media with a Microscale Lattice Boltzmann Model</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zhao, Jianlin; Yao, Jun; Zhang, Min; Zhang, Lei; Yang, Yongfei; Sun, Hai; An, Senyou; Li, Aifen</p> <p>2016-01-01</p> <p>To investigate the gas flow characteristics in tight <span class="hlt">porous</span> media, a microscale lattice Boltzmann (LB) model with the regularization procedure is firstly adopted to simulate gas flow in three-dimensional (3D) digital <span class="hlt">rocks</span>. A shale digital <span class="hlt">rock</span> and a sandstone digital <span class="hlt">rock</span> are reconstructed to study the effects of pressure, temperature and pore size on microscale gas flow. The simulation results show that because of the microscale effect in tight <span class="hlt">porous</span> media, the apparent permeability is always higher than the intrinsic permeability, and with the decrease of pressure or pore size, or with the increase of temperature, the difference between apparent permeability and intrinsic permeability increases. In addition, the Knudsen numbers under different conditions are calculated and the results show that gas flow characteristics in the digital <span class="hlt">rocks</span> under different Knudsen numbers are quite different. With the increase of Knudsen number, gas flow in the digital <span class="hlt">rocks</span> becomes more uniform and the effect of heterogeneity of the <span class="hlt">porous</span> media on gas flow decreases. Finally, two commonly used apparent permeability calculation models are evaluated by the simulation results and the Klinkenberg model shows better accuracy. In addition, a better proportionality factor in Klinkenberg model is proposed according to the simulation results. PMID:27587293</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22311236','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22311236"><span>Limitation of parallel flow in double diffusive convection: Two- and three-dimensional transitions in a horizontal <span class="hlt">porous</span> domain</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mimouni, N.; Chikh, S.; Rahli, O.; Bennacer, R.</p> <p>2014-07-15</p> <p>Two-dimensional (2D) and three-dimensional (3D) numerical simulations of double diffusion natural convection in an elongated enclosure filled with a binary <span class="hlt">fluid</span> <span class="hlt">saturating</span> a <span class="hlt">porous</span> medium are carried out in the present work. The Boussinesq approximation is made in the formulation of the problem, and Neumann boundary conditions for temperature and concentration are adopted, respectively, on vertical and horizontal walls of the cavity. The used numerical method is based on the control volume approach, with the third order quadratic upstream interpolation scheme in approximating the advection terms. A semi implicit method algorithm is used to handle the velocity-pressure coupling. To avoid the excessively high computer time inherent to the solution of 3D natural convection problems, full approximation storage with full multigrid method is used to solve the problem. A wide range of the controlling parameters (Rayleigh-Darcy number Ra, lateral aspect ratio Ay, Lewis number Le, and the buoyancy ration N) is investigated. We clearly show that increasing the depth of the cavity (i.e., the lateral aspect ratio) has an important effect on the flow patterns. The 2D perfect parallel flows obtained for small lateral aspect ratio are drastically destabilized by increasing the cavity lateral dimension. This yields a 3D fluid motion with a much more complex flow pattern and the usually considered 2D parallel flow model cannot be applied.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhFl...26k4102K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhFl...26k4102K"><span>Miscible gravitational instability of initially stable horizontal interface in a <span class="hlt">porous</span> medium: Non-monotonic density profiles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Min Chan</p> <p>2014-11-01</p> <p>To simulate a CO2 sequestration process, some researchers employed a water/propylene glycol (PPG) system which shows a non-monotonic density profile. Motivated by this fact, the stability of the diffusion layer of two miscible <span class="hlt">fluids</span> <span class="hlt">saturated</span> in a <span class="hlt">porous</span> medium is analyzed. For a non-monotonic density profile system, linear stability equations are derived in a global domain, and then transformed into a system of ordinary differential equations in an infinite domain. Initial growth rate analysis is conducted without the quasi-steady state approximation (QSSA) and shows that initially the system is unconditionally stable for the least stable disturbance. For the time evolving case, the ordinary differential equations are solved applying the eigen-analysis and numerical shooting scheme with and without the QSSA. To support these theoretical results, direct numerical simulations are conducted using the Fourier spectral method. The results of theoretical linear stability analyses and numerical simulations validate one another. The present linear and nonlinear analyses show that the water/PPG system is more unstable than the CO2/brine one, and the flow characteristics of these two systems are quite different from each other.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/sciencecinema/biblio/1254292','SCIGOVIMAGE-SCICINEMA'); return false;" href="http://www.osti.gov/sciencecinema/biblio/1254292"><span>Zapping <span class="hlt">Rocks</span> on Mars</span></a></p> <p><a target="_blank" href="http://www.osti.gov/sciencecinema/">ScienceCinema</a></p> <p>Wiens, Roger</p> <p>2016-07-12</p> <p>Better understanding Mars means better understanding its geology. That’s why, sitting atop NASA’s Curiosity rover, is ChemCam, an instrument built by Los Alamos National Laboratory that shoots lasers at Martian <span class="hlt">rocks</span> and analyzes the data. After nearly 1,500 <span class="hlt">rock</span> zaps, ChemCam has uncovered some surprising facts about the Red Planet, including the discovery of igneous <span class="hlt">rocks</span>. Soon, a new Los Alamos-built instrument—the SuperCam—will ride aboard the Mars 2020 rover and bring with it enhanced capabilities to unlock new secrets about the planet.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1254292','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1254292"><span>Zapping <span class="hlt">Rocks</span> on Mars</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wiens, Roger</p> <p>2016-05-16</p> <p>Better understanding Mars means better understanding its geology. That’s why, sitting atop NASA’s Curiosity rover, is ChemCam, an instrument built by Los Alamos National Laboratory that shoots lasers at Martian <span class="hlt">rocks</span> and analyzes the data. After nearly 1,500 <span class="hlt">rock</span> zaps, ChemCam has uncovered some surprising facts about the Red Planet, including the discovery of igneous <span class="hlt">rocks</span>. Soon, a new Los Alamos-built instrument—the SuperCam—will ride aboard the Mars 2020 rover and bring with it enhanced capabilities to unlock new secrets about the planet.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/865910','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/865910"><span>Detached <span class="hlt">rock</span> evaluation device</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Hanson, David R.</p> <p>1986-01-01</p> <p>A <span class="hlt">rock</span> detachment evaluation device (10) having an energy transducer unit 1) for sensing vibrations imparted to a subject <span class="hlt">rock</span> (172) for converting the sensed vibrations into electrical signals, a low band pass filter unit (12) for receiving the electrical signal and transmitting only a low frequency segment thereof, a high band pass filter unit (13) for receiving the electrical signals and for transmitting only a high frequency segment thereof, a comparison unit (14) for receiving the low frequency and high frequency signals and for determining the difference in power between the signals, and a display unit (16) for displaying indicia of the difference, which provides a quantitative measure of <span class="hlt">rock</span> detachment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA06273&hterms=bread&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dbread','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA06273&hterms=bread&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dbread"><span>Dirty Rotten <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/> This false-color image taken by the panoramic camera on the Mars Exploration Rover Spirit shows a collection of <span class="hlt">rocks</span> (upper right) at Gusev Crater that have captured the attention of scientists for their resemblance to rotting loaves of bread. The insides of the <span class="hlt">rocks</span> appear to have been eroded, while their outer rinds remain more intact. These outer rinds are reminiscent of those found on <span class="hlt">rocks</span> at Meridiani Planum's 'Eagle Crater.' This image was captured on sol 158 (June 13, 2004).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA06775&hterms=Aliens&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DAliens','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA06775&hterms=Aliens&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DAliens"><span>Weird 'Endurance' <span class="hlt">Rock</span> Ahead</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/> This image taken by the Mars Exploration Rover Opportunity shows a bizarre, lumpy <span class="hlt">rock</span> dubbed 'Wopmay' on the inner slopes of 'Endurance Crater.' Scientists say the <span class="hlt">rock</span>'s unusual texture is unlike any others observed so far at Meridiani Planum. Wopmay measures approximately 1 meter (3.3 feet) across. The image was taken by the rover's panoramic camera on sol 195 (Aug. 11, 2004). Opportunity will likely travel to this or a similar <span class="hlt">rock</span> in coming sols for a closer look at the alien surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA06775&hterms=alien&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dalien','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA06775&hterms=alien&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dalien"><span>Weird 'Endurance' <span class="hlt">Rock</span> Ahead</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/> This image taken by the Mars Exploration Rover Opportunity shows a bizarre, lumpy <span class="hlt">rock</span> dubbed 'Wopmay' on the inner slopes of 'Endurance Crater.' Scientists say the <span class="hlt">rock</span>'s unusual texture is unlike any others observed so far at Meridiani Planum. Wopmay measures approximately 1 meter (3.3 feet) across. The image was taken by the rover's panoramic camera on sol 195 (Aug. 11, 2004). Opportunity will likely travel to this or a similar <span class="hlt">rock</span> in coming sols for a closer look at the alien surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA00940&hterms=Gardens&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DGardens','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA00940&hterms=Gardens&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DGardens"><span><span class="hlt">Rock</span> Garden Mosaic</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1997-01-01</p> <p>This image mosaic of part of the '<span class="hlt">Rock</span> Garden' was taken by the Sojourner rover's left front camera on Sol 71 (September 14). The <span class="hlt">rock</span> 'Shark' is at left center and 'Half Dome' is at right. Fine-scale textures on the <span class="hlt">rocks</span> are clearly seen. Broken crust-like material is visible at bottom center.<p/>Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA06273&hterms=bread&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dbread','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA06273&hterms=bread&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dbread"><span>Dirty Rotten <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/> This false-color image taken by the panoramic camera on the Mars Exploration Rover Spirit shows a collection of <span class="hlt">rocks</span> (upper right) at Gusev Crater that have captured the attention of scientists for their resemblance to rotting loaves of bread. The insides of the <span class="hlt">rocks</span> appear to have been eroded, while their outer rinds remain more intact. These outer rinds are reminiscent of those found on <span class="hlt">rocks</span> at Meridiani Planum's 'Eagle Crater.' This image was captured on sol 158 (June 13, 2004).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080006880','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080006880"><span>Small, <span class="hlt">porous</span> polyacrylate beads</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rembaum, Alan (Inventor); Yen, Shiao-Ping Siao (Inventor); Dreyer, William J. (Inventor)</p> <p>1976-01-01</p> <p>Uniformly-shaped, <span class="hlt">porous</span>, round beads are prepared by the co-polymerization of an acrylic monomer and a cross-linking agent in the presence of 0.05 to 5% by weight of an aqueous soluble polymer such as polyethylene oxide. Cross-linking proceeds at high temperature above about 50.degree.C or at a lower temperature with irradiation. Beads of even shape and even size distribution of less than 2 micron diameter are formed. The beads will find use as adsorbents in chromatography and as markers for studies of cell surface receptors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080012236','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080012236"><span>Crosslinked, <span class="hlt">porous</span>, polyacrylate beads</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rembaum, Alan (Inventor); Yen, Shiao-Ping S. (Inventor); Dreyer, William J. (Inventor)</p> <p>1977-01-01</p> <p>Uniformly-shaped, <span class="hlt">porous</span>, round beads are prepared by the co-polymerization of an acrylic monomer and a cross-linking agent in the presence of 0.05 to 5% by weight of an aqueous soluble polymer such as polyethylene oxide. Cross-linking proceeds at high temperature above about 50.degree. C or at a lower temperature with irradiation. Beads of even shape and even size distribution of less than 2 micron diameter are formed. The beads will find use as adsorbents in chromatography and as markers for studies of cell surface receptors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17979254','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17979254"><span>Tortuosity of <span class="hlt">porous</span> particles.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Barrande, M; Bouchet, R; Denoyel, R</p> <p>2007-12-01</p> <p>Tortuosity is often used as an adjustable parameter in models of transfer properties through <span class="hlt">porous</span> media. This parameter, not reducible to classical measured microstructural parameters like specific surface area, porosity, or pore size distribution, reflects the efficiency of percolation paths, which is linked to the topology of the material. The measurement of the effective conductivity of a bed of particles saturated with an electrolyte is a simple way to evaluate tortuosity. Nevertheless, it received only little attention because of the real difficulties in both getting reliable results and interpreting data. Notably, the discrimination between the contribution of interparticle and intraparticle porosities to the tortuosity is not resolved. To our knowledge, there is no model able to fit the experimental data of the tortuosity of a suspension, and a fortiori of a particle bed, in the whole porosity range. Only empirical expressions have been proposed, but they do not allow deriving intratortuosity of a <span class="hlt">porous</span> particle. For a dilute system, Maxwell's equation predicts the effective conductivity of suspensions of spherical particles as a function of the bulk electrolyte conductivity and of particle conductivity. The intraparticle tortuosity can be derived from the particle conductivity obtained from the Maxwell equation applied to data at infinite dilution of particles. Then, by assuming that the Maxwell equation is a first-order approximation of the conductivity as a function of porosity, we propose an explicit relation of the tortuosity tau of a suspension of <span class="hlt">porous</span> particles, obtained by conductivity measurement, as tau = tau(epsilon, epsilon(p), tau(p)), where epsilon is the total porosity of the suspension, tau(p) is the intraparticle tortuosity, and epsilon(p) is the particle porosity. This relationship fits the experimental data in the whole porosity range and can be used to determine tau(p) from an experiment at only one porosity. Finally, the obtained</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/872975','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/872975"><span>Rigid <span class="hlt">porous</span> filter</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Chiang, Ta-Kuan; Straub, Douglas L.; Dennis, Richard A.</p> <p>2000-01-01</p> <p>The present invention involves a <span class="hlt">porous</span> rigid filter including a plurality of concentric filtration elements having internal flow passages and forming external flow passages there between. The present invention also involves a pressure vessel containing the filter for the removal of particulates from high pressure particulate containing gases, and further involves a method for using the filter to remove such particulates. The present filter has the advantage of requiring fewer filter elements due to the high surface area-to-volume ratio provided by the filter, requires a reduced pressure vessel size, and exhibits enhanced mechanical design properties, improved cleaning properties, configuration options, modularity and ease of fabrication.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18272450','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18272450"><span>Why engineer <span class="hlt">porous</span> materials?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kelly, A</p> <p>2006-01-15</p> <p>A number of specific examples are briefly given for the use of pores in engineering materials: a <span class="hlt">porous</span> ceramic to produce minimum thermal conduction; thin skeleton walls in silicon to produce photoluminescence; low dielectric constant materials. The desirable nature of the pores in fuel cell electrodes and sieves is described. Further examples are given in orthopaedics, prosthetic scaffolds and sound deadening and impact resistance materials. An attempt is made to describe the desirable pore size, whether open or closed, and the useful volume fraction. This short review does not deal with flexible foams.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23510512','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23510512"><span>Photoactive <span class="hlt">porous</span> silicon nanopowder.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Meekins, Benjamin H; Lin, Ya-Cheng; Manser, Joseph S; Manukyan, Khachatur; Mukasyan, Alexander S; Kamat, Prashant V; McGinn, Paul J</p> <p>2013-04-24</p> <p>Bulk processing of <span class="hlt">porous</span> silicon nanoparticles (nSi) of 50-300 nm size and surface area of 25-230 m(2)/g has been developed using a combustion synthesis method. nSi exhibits consistent photoresponse to AM 1.5 simulated solar excitation. In confirmation of photoactivity, the films of nSi exhibit prompt bleaching following femtosecond laser pulse excitation resulting from the photoinduced charge separation. Photocurrent generation observed upon AM 1.5 excitation of these films in a photoelectrochemical cell shows strong dependence on the thickness of the intrinsic silica shell that encompasses the nanoparticles and hinders interparticle electron transfer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080006886','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080006886"><span>Crosslinked, <span class="hlt">porous</span>, polyacrylate beads</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rembaum, Alan (Inventor); Yen, Shiao-Ping Siao (Inventor); Dreyer, William J. (Inventor)</p> <p>1976-01-01</p> <p>Uniformly-shaped, <span class="hlt">porous</span>, round beads are prepared by the co-polymerization of an acrylic monomer and a cross-linking agent in the presence of 0.05 to 5% by weight of an aqueous soluble polymer such as polyethylene oxide. Cross-linking proceeds at high temperature above about 50.degree.C or at a lower temperature with irradiation. Beads of even shape and even size distribution of less than 2 micron diameter are formed. The beads will find use as adsorbents in chromatography and as markers for studies of cell surface receptors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017E%26PSL.462...99C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E%26PSL.462...99C"><span>The evolution of pore connectivity in volcanic <span class="hlt">rocks</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Colombier, Mathieu; Wadsworth, Fabian B.; Gurioli, Lucia; Scheu, Bettina; Kueppers, Ulrich; Di Muro, Andrea; Dingwell, Donald B.</p> <p>2017-03-01</p> <p>Pore connectivity is a measure of the fraction of pore space (vesicles, voids or cracks) in a material that is interconnected on the system length scale. Pore connectivity is fundamentally related to permeability, which has been shown to control magma outgassing and the explosive potential of magma during ascent in the shallowest part of the crust. Here, we compile a database of connectivity and porosity from published sources and supplement this with additional measurements, using natural volcanic <span class="hlt">rocks</span> produced in a broad range of eruptive styles and with a range of bulk composition. The database comprises 2715 pairs of connectivity C and porosity ϕ values for <span class="hlt">rocks</span> from 35 volcanoes as well as 116 products of experimental work. For 535 volcanic <span class="hlt">rock</span> samples, the permeability k was also measured. Data from experimental studies constrain the general features of the relationship between C and ϕ associated with both vesiculation and densification processes, which can then be used to interpret natural data. To a first order, we show that a suite of <span class="hlt">rocks</span> originating from effusive eruptive behaviour can be distinguished from <span class="hlt">rocks</span> originating from explosive eruptive behaviour using C and ϕ. We observe that on this basis, a particularly clear distinction can be made between scoria formed in fire-fountains and that formed in Strombolian activity. With increasing ϕ, the onset of connectivity occurs at the percolation threshold ϕc which in turn can be hugely variable. We demonstrate that C is an excellent metric for constraining ϕc in suites of <span class="hlt">porous</span> <span class="hlt">rocks</span> formed in a common process and discuss the range of ϕc values recorded in volcanic <span class="hlt">rocks</span>. The percolation threshold is key to understanding the onset of permeability, outgassing and compaction in shallow magmas. We show that this threshold is dramatically different in <span class="hlt">rocks</span> formed during densification processes than in <span class="hlt">rocks</span> formed in vesiculating processes and propose that this value is the biggest factor in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=%22mineral+resources%22&id=EJ480223','ERIC'); return false;" href="http://eric.ed.gov/?q=%22mineral+resources%22&id=EJ480223"><span>Focus on the <span class="hlt">Rock</span>.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Shewell, John</p> <p>1994-01-01</p> <p>Describes historical accounts of the manipulation and importance of the Earth and its mineral resources. A foldout, "Out of the <span class="hlt">Rock</span>," provides a collection of activities and information that helps make integration of the aforementioned concepts easy. (ZWH)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.youtube.com/watch?v=SFIM0EIt17o','SCIGOVIMAGE-NASA'); return false;" href="http://www.youtube.com/watch?v=SFIM0EIt17o"><span>Our World: Lunar <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p></p> <p>Learn about NASA'€™s Lunar Sample Laboratory Facility at Johnson Space Center in Houston, Texas. See how NASA protects these precious moon <span class="hlt">rocks</span> brought to Earth by the Apollo astronauts. Explore t...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA08702.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA08702.html"><span>Many-Layered <span class="hlt">Rock</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2006-08-23</p> <p>This MOC image shows light-toned, layered, sedimentary <span class="hlt">rocks</span> in a crater in the northwestern part of Schiaparelli basin. The repetition of these horizontal layers suggests the sediments could have been deposited in an ancient crater lake</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=harmony+AND+music&pg=6&id=EJ011744','ERIC'); return false;" href="http://eric.ed.gov/?q=harmony+AND+music&pg=6&id=EJ011744"><span><span class="hlt">Rock</span> in Its Elements</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>MacCluskey, Thomas</p> <p>1969-01-01</p> <p>A discussion of the following musical elements of <span class="hlt">rock</span>: rhythm, melody, harmony, and form. A impromptu analysis made at a session of the Youth Music Symposium, July 25, 1969. Remarks transcribed from tape. (Author/AP)</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA00680.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA00680.html"><span>Prominent <span class="hlt">Rocks</span> - 3-D</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>1997-07-13</p> <p>Many prominent <span class="hlt">rocks</span> near the Sagan Memorial Station are featured in this image from NASA Mars Pathfinder. Shark, Half-Dome, and Pumpkin are at center 3D glasses are necessary to identify surface detail.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA05641&hterms=Sedimentary+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DSedimentary%2Brocks','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA05641&hterms=Sedimentary+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DSedimentary%2Brocks"><span>Terby's Layered <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>14 March 2004 Layered <span class="hlt">rock</span> outcrops are common all across Mars, and the Mars rover, Opportunity, has recently investigated some layered <span class="hlt">rocks</span> in Meridiani Planum. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layered sedimentary <span class="hlt">rocks</span> in northern Terby Crater, located just north of the giant Hellas Basin near 27.5oS, 285.8oW. Hundreds of layers are exposed in a deposit several kilometers thick within Terby. A history of events that shaped the northern Hellas region is recorded in these <span class="hlt">rocks</span>, just waiting for a person or robot to investigate. The picture covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the left.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA07951&hterms=Sedimentary+rocks&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSedimentary%2Brocks','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA07951&hterms=Sedimentary+rocks&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSedimentary%2Brocks"><span>Broken Sedimentary <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2005-01-01</p> <p><p/> 18 May 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows broken-up blocks of sedimentary <span class="hlt">rock</span> in western Candor Chasma. There are several locations in western Candor that exhibit this pattern of broken <span class="hlt">rock</span>. The manner in which these landforms were created is unknown; it is possible that there was a landslide or a meteoritic impact that broke up the materials. One attribute that is known: in some of these cases, it seems that the <span class="hlt">rock</span> was broken and then buried by later sedimentary <span class="hlt">rocks</span>, before later being exhumed so that they can be seen from orbit today. <p/> <i>Location near</i>: 6.9oS, 75.5oW <i>Image width</i>: 3 km (1.9 mi) <i>Illumination from</i>: upper left <i>Season</i>: Southern Winter</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA04911&hterms=Sedimentary+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DSedimentary%2Brocks','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA04911&hterms=Sedimentary+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DSedimentary%2Brocks"><span>Tithonium Chasma's Sedimentary <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2003-01-01</p> <p>MGS MOC Release No. MOC2-565, 5 December 2003<p/>Exposures of light-toned, layered, sedimentary <span class="hlt">rocks</span> are common in the deep troughs of the Valles Marineris system. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example from western Tithonium Chasma. The banding seen here is an eroded expression of layered <span class="hlt">rock</span>. Sedimentary <span class="hlt">rocks</span> can be composed of (1) the detritus of older, eroded and weathered <span class="hlt">rocks</span>, (2) grains produced by explosive volcanism (tephra, also known as volcanic ash), or (3) minerals that were chemically precipitated out of a body of liquid such as water. These outcrops are located near 4.8oS, 89.7oW. The image covers an area 3 km (1.9 mi) wide and is illuminated from the lower left.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA04721&hterms=Sedimentary+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DSedimentary%2Brocks','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA04721&hterms=Sedimentary+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DSedimentary%2Brocks"><span>Ancient Sedimentary <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2003-01-01</p> <p>MGS MOC Release No. MOC2-469, 31 August 2003<p/>The terraced area in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image is an outcropping of ancient, sedimentary <span class="hlt">rock</span>. It occurs in a crater in western Arabia Terra near 10.8oN, 4.5oW. Sedimentary <span class="hlt">rocks</span> provide a record of past environments on Mars. Field work will likely be required to begin to get a good understanding of the nature of the record these <span class="hlt">rocks</span> contain. Their generally uniform thickness and repeated character suggests that deposition of fine sediment in this crater was episodic, if not cyclic. These <span class="hlt">rocks</span> might be indicators of an ancient lake, or they might have been deposited from grains settling out of an earlier, thicker, martian atmosphere. This image covers an area 3 km (1.9 mi) across and is illuminated from the lower left.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=mineral+AND+resources&pg=2&id=EJ480223','ERIC'); return false;" href="https://eric.ed.gov/?q=mineral+AND+resources&pg=2&id=EJ480223"><span>Focus on the <span class="hlt">Rock</span>.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Shewell, John</p> <p>1994-01-01</p> <p>Describes historical accounts of the manipulation and importance of the Earth and its mineral resources. A foldout, "Out of the <span class="hlt">Rock</span>," provides a collection of activities and information that helps make integration of the aforementioned concepts easy. (ZWH)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://files.eric.ed.gov/fulltext/EJ225290.pdf','ERIC'); return false;" href="http://files.eric.ed.gov/fulltext/EJ225290.pdf"><span>Writing <span class="hlt">Rock</span> Music Reviews.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Brown, Donal</p> <p>1980-01-01</p> <p>Suggests ways student reviewers of <span class="hlt">rock</span> music groups can write better reviews. Among the suggestions made are that reviewers occasionally discuss the audience or what makes a particular group unique, support general comment with detail, and avoid ecstatic adjectives. (TJ)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA06883&hterms=Igneous+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DIgneous%2Brocks','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA06883&hterms=Igneous+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DIgneous%2Brocks"><span>East Candor <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/> 24 September 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a thick, massive outcrop of light-toned <span class="hlt">rock</span> exposed within eastern Candor Chasma, part of the vast Valles Marineris trough system. Dark, windblown sand has banked against the lower outcrop slopes. Outcrops such as this in the Valles Marineris chasms have been known since Mariner 9 images were obtained in 1972. However, the debate as to whether these represent sedimentary or igneous <span class="hlt">rocks</span> has not been settled within the Mars science community. In either case, they have the physical properties of sedimentary <span class="hlt">rock</span> (that is, they are formed of fine-grained materials), but some igneous <span class="hlt">rocks</span> made up of volcanic ash may also exhibit these properties. This image is located near 7.8oS, 65.3oW, and covers an area approximately 3 km (1.9 mi) across. The scene is illuminated by sunlight from the lower left.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA05641&hterms=history+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dhistory%2Brocks','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA05641&hterms=history+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dhistory%2Brocks"><span>Terby's Layered <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>14 March 2004 Layered <span class="hlt">rock</span> outcrops are common all across Mars, and the Mars rover, Opportunity, has recently investigated some layered <span class="hlt">rocks</span> in Meridiani Planum. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layered sedimentary <span class="hlt">rocks</span> in northern Terby Crater, located just north of the giant Hellas Basin near 27.5oS, 285.8oW. Hundreds of layers are exposed in a deposit several kilometers thick within Terby. A history of events that shaped the northern Hellas region is recorded in these <span class="hlt">rocks</span>, just waiting for a person or robot to investigate. The picture covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the left.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/865714','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/865714"><span><span class="hlt">Porous</span> metallic bodies</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Landingham, Richard L.</p> <p>1985-01-01</p> <p><span class="hlt">Porous</span> metallic bodies having a substantially uniform pore size of less than about 200 microns and a density of less than about 25 percent theoretical, as well as the method for making them, are disclosed. Group IIA, IIIB, IVB, VB, and rare earth metal hydrides are heated in a confining container at a controlled rate to a temperature of about greater than the temperature at which the hydride decomposes. Hydrogen is removed from the container and the remaining metal is heated during a second stage to a temperature greater than the temperature at which it was previously heated but not greater than the temperature of 1/2 to 2/3 the temperature at which the metal melts at a controlled rate. The resulting <span class="hlt">porous</span> metallic body produced has a density less than about 25 percent theoretical and a pore size of less than about 200 microns. The metallic particles of the present invention have high inner surface area and possess minimum resistance to gas flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/79095','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/79095"><span>Predicting the transport properties of sedimentary <span class="hlt">rocks</span> from microstructure</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Schlueter, Erika M.</p> <p>1995-01-01</p> <p>Understanding transport properties of sedimentary <span class="hlt">rocks</span>, including permeability, relative permeability, and electrical conductivity, is of great importance for petroleum engineering, waste isolation, environmental restoration, and other applications. These transport properties axe controlled to a great extent by the pore structure. How pore geometry, topology, and the physics and chemistry of mineral-fluid and fluid-fluid interactions affect the flow of fluids through consolidated/partially consolidated <span class="hlt">porous</span> media are investigated analytically and experimentally. Hydraulic and electrical conductivity of sedimentary <span class="hlt">rocks</span> are predicted from the microscopic geometry of the pore space. Cross-sectional areas and perimeters of individual pores are estimated from two-dimensional scanning electron microscope (SEM) photomicrographs of <span class="hlt">rock</span> sections. Results, using Berea, Boise, Massilon, and Saint-Gilles sandstones show close agreement between the predicted and measured permeabilities. Good to fair agreement is found in the case of electrical conductivity. In particular, good agreement is found for a poorly cemented <span class="hlt">rock</span> such as Saint-Gilles sandstone, whereas the agreement is not very good for well-cemented <span class="hlt">rocks</span>. The possible reasons for this are investigated. The surface conductance contribution of clay minerals to the overall electrical conductivity is assessed. The effect of partial hydrocarbon saturation on overall <span class="hlt">rock</span> conductivity, and on the Archie saturation exponent, is discussed. The region of validity of the well-known Kozeny-Carman permeability formulae for consolidated <span class="hlt">porous</span> media and their relationship to the microscopic spatial variations of channel dimensions are established. It is found that the permeabilities predicted by the Kozeny-Carman equations are valid within a factor of three of the observed values methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMMR43A..01M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMMR43A..01M"><span>3D Printing and Digital <span class="hlt">Rock</span> Physics for Geomaterials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martinez, M. J.; Yoon, H.; Dewers, T. A.</p> <p>2015-12-01</p> <p>Imaging techniques for the analysis of <span class="hlt">porous</span> structures have revolutionized our ability to quantitatively characterize geomaterials. Digital representations of <span class="hlt">rock</span> from CT images and physics modeling based on these pore structures provide the opportunity to further advance our quantitative understanding of fluid flow, geomechanics, and geochemistry, and the emergence of coupled behaviors. Additive manufacturing, commonly known as 3D printing, has revolutionized production of custom parts with complex internal geometries. For the geosciences, recent advances in 3D printing technology may be co-opted to print reproducible <span class="hlt">porous</span> structures derived from CT-imaging of actual <span class="hlt">rocks</span> for experimental testing. The use of 3D printed microstructure allows us to surmount typical problems associated with sample-to-sample heterogeneity that plague <span class="hlt">rock</span> physics testing and to test material response independent from pore-structure variability. Together, imaging, digital <span class="hlt">rocks</span> and 3D printing potentially enables a new workflow for understanding coupled geophysical processes in a real, but well-defined setting circumventing typical issues associated with reproducibility, enabling full characterization and thus connection of physical phenomena to structure. In this talk we will discuss the possibilities that these technologies can bring to geosciences and present early experiences with coupled multiscale experimental and numerical analysis using 3D printed fractured <span class="hlt">rock</span> specimens. In particular, we discuss the processes of selection and printing of transparent fractured specimens based on 3D reconstruction of micro-fractured <span class="hlt">rock</span> to study fluid flow characterization and manipulation. Micro-particle image velocimetry is used to directly visualize 3D single and multiphase flow velocity in 3D fracture networks. 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016CPM.....3..141H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016CPM.....3..141H"><span>Characterizing flow in oil reservoir <span class="hlt">rock</span> using SPH: absolute permeability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Holmes, David W.; Williams, John R.; Tilke, Peter; Leonardi, Christopher R.</p> <p>2016-04-01</p> <p>In this paper, a three-dimensional smooth particle hydrodynamics (SPH) simulator for modeling grain scale fluid flow in <span class="hlt">porous</span> <span class="hlt">rock</span> is presented. The versatility of the SPH method has driven its use in increasingly complex areas of flow analysis, including flows related to permeable <span class="hlt">rock</span> for both groundwater and petroleum reservoir research. While previous approaches to such problems using SPH have involved the use of idealized pore geometries (cylinder/sphere packs etc), in this paper we detail the characterization of flow in models with geometries taken from 3D X-ray microtomographic imaging of actual <span class="hlt">porous</span> <span class="hlt">rock</span>; specifically 25.12 % porosity dolomite. This particular <span class="hlt">rock</span> type has been well characterized experimentally and described in the literature, thus providing a practical `real world' means of verification of SPH that will be key to its acceptance by industry as a viable alternative to traditional reservoir modeling tools. The true advantages of SPH are realized when adding the complexity of multiple fluid phases, however, the accuracy of SPH for single phase flow is, as yet, under developed in the literature and will be the primary focus of this paper. Flow in reservoir <span class="hlt">rock</span> will typically occur in the range of low Reynolds numbers, making the enforcement of no-slip boundary conditions an important factor in simulation. To this end, we detail the development of a new, robust, and numerically efficient method for implementing no-slip boundary conditions in SPH that can handle the degree of complexity of boundary surfaces, characteristic of an actual permeable <span class="hlt">rock</span> sample. A study of the effect of particle density is carried out and simulation results for absolute permeability are presented and compared to those from experimentation showing good agreement and validating the method for such applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-201303120001HQ.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-201303120001HQ.html"><span>Mars <span class="hlt">Rock</span> Analysis Briefing</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2013-03-12</p> <p>Michael Meyer (left), lead scientist, Mars Exploration Program at NASA Headquarters, speaks at a news conference presenting findings of the Curiosity rover's analysis of the first sample of <span class="hlt">rock</span> powder collected on Mars, Tuesday, March 12, 2013 in Washington. The <span class="hlt">rock</span> sample collected shows ancient Mars could have supported living microbes. John Grotzinger, Curiosity project scientist, California Institute of Technology is seen on the right. Photo Credit: (NASA/Carla Cioffi)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/336696','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/336696"><span>Fractal Geometry of <span class="hlt">Rocks</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Radlinski, A.P.; Radlinska, E.Z.; Agamalian, M.; Wignall, G.D.; Lindner, P.; Randl, O.G.</p> <p>1999-04-01</p> <p>The analysis of small- and ultra-small-angle neutron scattering data for sedimentary <span class="hlt">rocks</span> shows that the pore-<span class="hlt">rock</span> fabric interface is a surface fractal (D{sub s}=2.82) over 3 orders of magnitude of the length scale and 10 orders of magnitude in intensity. The fractal dimension and scatterer size obtained from scanning electron microscopy image processing are consistent with neutron scattering data. {copyright} {ital 1999} {ital The American Physical Society}</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-201303120003HQ.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-201303120003HQ.html"><span>Mars <span class="hlt">Rock</span> Analysis Briefing</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2013-03-12</p> <p>Paul Mahaffy (right), principal investigator for Curiosity's Sample Analysis at Mars (SAM) investigation at NASA's Goddard Space Flight Center in Maryland, demonstrates how the SAM instrument drilled and captured <span class="hlt">rock</span> samples on the surface of Mars at a news conference, Tuesday, March 12, 2013 at NASA Headquarters in Washington. The analysis of the <span class="hlt">rock</span> sample collected shows ancient Mars could have supported living microbes. Photo Credit: (NASA/Carla Cioffi)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/93963','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/93963"><span>The influence of <span class="hlt">rock</span> material models on seismic discrimination of underground nuclear explosions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Glenn, L.A.</p> <p>1995-06-01</p> <p>We found that the spectral characteristics of the seismic signal from underground explosions were mainly determined by the <span class="hlt">rock</span> material strength and the gas porosity. Both the unloading characteristics and the amplitude of the ``elastic toe`` are important parameters in the <span class="hlt">porous</span> model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017DokES.475..736K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017DokES.475..736K"><span>Evolution of sedimentary <span class="hlt">rock</span> formation of a <span class="hlt">rock</span> association level</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuznetsov, V. G.</p> <p>2017-07-01</p> <p>The evolution of sedimentary <span class="hlt">rock</span> formation of a highly organized level (paragenetic <span class="hlt">rock</span> associations) is more complex than that of a poorly organized level (<span class="hlt">rocks</span>). Subjacent <span class="hlt">rock</span> associations are established for the entire geological evolution of the Earth: they varied in time and were obsolescent or, in contrast, nascent and momentary. A certain cyclicity of evolution is identified along with directed changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatPh..11..835G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatPh..11..835G"><span>Dynamic patterns of compaction in brittle <span class="hlt">porous</span> media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guillard, François; Golshan, Pouya; Shen, Luming; Valdes, Julio R.; Einav, Itai</p> <p>2015-10-01</p> <p>Brittle <span class="hlt">porous</span> media exhibit a variety of irreversible patterns during densification, including stationary and moving compaction bands in <span class="hlt">rocks</span>, foams, cereal packs and snow. We have recently found moving compaction bands in cereal packs; similar bands have been detected in snow. However, the question of generality remains: under what conditions can brittle <span class="hlt">porous</span> media disclose other densification patterns? Here, using a new heuristic lattice spring model undergoing repeated crushing events, we first predict the possible emergence of new types of dynamic compaction; we then discover and confirm these new patterns experimentally in compressed cereal packs. In total, we distinguish three observed compaction patterns: short-lived erratic compaction bands, multiple oscillatory propagating compaction bands reminiscent of critical phenomena near phase transitions, and diffused irreversible densification. The manifestation of these three different patterns is mapped in a phase diagram using two dimensionless groups that represent fabric collapse and external dissipation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5715074','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5715074"><span>Analytic studies of colloid transport in fractured <span class="hlt">porous</span> media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hwang, Y.; Chambre, P.L.; Lee, W.W.L.; Pigford, T.H.</p> <p>1989-11-01</p> <p>We analyze the interactive migration of radioactive colloids and solute in fractured <span class="hlt">rock</span>. Two possible interactions between radionuclides as colloids and as solute are considered: solute sorption on nonradioactive colloids to form pseudocolloids, and dissolution of radioactive colloids. Previous studies have discussed the formation and transport of colloids in <span class="hlt">porous</span> media, including removal of colloids by filtration and sedimentation. Colloids can migrate faster than solute because of weaker sorption on stationary solids and because of hydrochromatography of colloid particles in flow channels. However, the migration of colloids and pseudocolloids can be retarded by the interaction of colloids with solute, and the migration of solute in local equilibrium with colloids can be more rapid than if colloids were not present. Here we present a new quantative analysis to predict the interactive migration of colloids and solute in <span class="hlt">porous</span> and fractured media. 4 figs.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. Their policies may differ from this site.</small> </div> </center> <div id="footer-wrapper"> <div class="footer-content"> <div id="footerOSTI" class=""> <div class="row"> <div class="col-md-4 text-center col-md-push-4 footer-content-center"><small><a href="http://www.science.gov/disclaimer.html">Privacy and Security</a></small> <div class="visible-sm visible-xs push_footer"></div> </div> <div class="col-md-4 text-center col-md-pull-4 footer-content-left"> <img src="https://www.osti.gov/images/DOE_SC31.png" alt="U.S. Department of Energy" usemap="#doe" height="31" width="177"><map style="display:none;" name="doe" id="doe"><area shape="rect" coords="1,3,107,30" href="http://www.energy.gov" alt="U.S. Deparment of Energy"><area shape="rect" coords="114,3,165,30" href="http://www.science.energy.gov" alt="Office of Science"></map> <a ref="http://www.osti.gov" style="margin-left: 15px;"><img src="https://www.osti.gov/images/footerimages/ostigov53.png" alt="Office of Scientific and Technical Information" height="31" width="53"></a> <div class="visible-sm visible-xs push_footer"></div> </div> <div class="col-md-4 text-center footer-content-right"> <a href="http://www.science.gov"><img src="https://www.osti.gov/images/footerimages/scigov77.png" alt="science.gov" height="31" width="98"></a> <a href="http://worldwidescience.org"><img src="https://www.osti.gov/images/footerimages/wws82.png" alt="WorldWideScience.org" height="31" width="90"></a> </div> </div> </div> </div> </div> <p><br></p> </div><!-- container --> <script type="text/javascript"><!-- // var lastDiv = ""; function showDiv(divName) { // hide last div if (lastDiv) { document.getElementById(lastDiv).className = "hiddenDiv"; } //if value of the box is not nothing and an object with that name exists, then change the class if (divName && document.getElementById(divName)) { document.getElementById(divName).className = "visibleDiv"; lastDiv = divName; } } //--> </script> <script> /** * Function that tracks a click on an outbound link in Google Analytics. * This function takes a valid URL string as an argument, and uses that URL string * as the event label. */ var trackOutboundLink = function(url,collectionCode) { try { h = window.open(url); setTimeout(function() { ga('send', 'event', 'topic-page-click-through', collectionCode, url); }, 1000); } catch(err){} }; </script> <!-- Google Analytics --> <script> (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){ (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o), m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m) })(window,document,'script','//www.google-analytics.com/analytics.js','ga'); ga('create', 'UA-1122789-34', 'auto'); ga('send', 'pageview'); </script> <!-- End Google Analytics --> <script> showDiv('page_1') </script> </body> </html>