The effects of porosity and clay content on wave velocities in sandstones

Han, De‐hua; Nur, Amos

doi:10.1190/1.1893163

Cited by 406 publications

(288 citation statements)

References 3 publications

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“…With increasing porosity, V p decreases gradually in a nonlinear fashion, confirming the observations of other researchers on loose sediments [11,12], but contradicting that on cemented sandstones, where an approximate linear correlation between porosity and V p is observed [13,14]. In low porosity cemented sandstones, the propagation of compressional waves is dominantly via the inter-connected solid sand frame, in which case, a small increase in porosity will dramatically decrease the bulk and shear moduli of the rock resulting in a rapid reduction of the wave velocities.…”

Section: Elastic Velocity and Porositysupporting

confidence: 80%

Joint elastic-electrical properties of sediments in the Yellow Sea

Han

Liu

Kan

et al. 2011

Sci. China Earth Sci.

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We measured in the laboratory compressional wave velocity and electrical resistivity on 434 sediment samples collected from the Yellow Sea to study the joint elastic-electrical properties of marine sediments. Porosity was found to reduce both elastic velocity and electrical resistivity of the marine sediments in a non-linear fashion; velocity showed an approximate linear increase with increasing logarithm of resistivity. Various effective medium models either implemented or developed were compared with the new dataset. The model results showed that the combined self-consistent approximation and differential effective medium model using critical porosity of 0.6 and 0.5 for velocity and resistivity respectively gave a reasonable description of the joint elastic-electrical behaviors of the marine sediments. The joint elastic-electrical properties of the marine sediments established would be used to estimate resistivity from measured velocity and vice versa, and could also be suitable for detection of gas hydrate or other suitable targets from joint seismic-resistivity surveys. joint elastic-electrical properties, marine sediments, Yellow Sea, effective medium models Marine sediments on the shallow surface of seafloor are an important interface between sea water and the rocks beneath in terms of their transitional physical properties. The acoustic properties (mainly sound speed and attenuation) of marine sediments are key factors that affect sound spatial structure, underwater sound communication, underwater objection locating, and underwater sonar performance, and are therefore being significant research topics of military oceanography and military geophysics that play an important role in national coast defenses [1,2]. On the other hand, the measurements of electrical properties (e.g. electrical resistivity or its inverse electrical conductivity) of marine sediments provide valuable information for marine engineering [3] and resource [4,5] investigations and seafloor environmental monitoring [6].Recent development in in-situ seafloor sediments acoustic equipment [1,7] and the controlled source electromagnetic (CSEM) techniques [8] has made the accurate joint elastic-electrical measurements of marine sediments possible, which can give a better evaluation of the sedimentological properties (e.g. porosity and brine or gas content) provided that the inter-relationships among sediment engineering and the joint elastic-electrical properties of marine sediments are known. There has been joint elastic-electrical research on sedimentary rocks (e.g. reservoir sandstones) [9, 10], but unfortunately none relevant work on marine sediments can be found in the open literature.We aim in this paper to establish the relationship between compressional wave velocity (V p ) and electrical resistivity (  ) of marine sediments (referred to as the joint elastic-electrical properties) based on comprehensive laboratory

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Section: Elastic Velocity and Porositysupporting

confidence: 80%

Joint elastic-electrical properties of sediments in the Yellow Sea

Han

Liu

Kan

et al. 2011

Sci. China Earth Sci.

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“…Furthermore, we Voigt-Reuss-Hill average of C s 23.9 6.7 a Clay properties were extrapolated by Hornby et al [48] from the results of Marion et al [57] to zero percent porosity using an isotropic self-consistent approximation b Clay properties were suggested by Berge and Berryman [9] using a compilation of laboratory measurements in Castagna et al [18] c Properties of 'gulf clays' cited in [58], referencing the data from Han et al [39] and Blangy [8]. Clay velocities were interpreted by Castagna et al [19] through extrapolating empirical relations for mixed lithologies to 100% clay d Clay properties were obtained from acoustic velocity measurements of clay powders (in dry compacted form and in water suspension) confirm previous observations that the in situ elasticity values are one order of magnitude smaller than the few reported clay mineral stiffness values [58,75,81].…”

Section: Level '0' Order-of-magnitude Checkmentioning

confidence: 99%

The effect of the nanogranular nature of shale on their poroelastic behavior

2007

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Natural composite materials are highly heterogeneous porous materials, with porosities that manifest themselves at scales much below the macroscale of engineering applications. A typical example is shale, the transverse isotropic sealing formation of most hydrocarbon bearing reservoirs. By means of a closed loop approach of microporomechanics modeling, calibration and validation of elastic properties at multiple length scales of shale, we show that the nanogranular nature of this highly heterogeneous material translates into a unique poroelastic signature. The self-consistent scaling of the porous clay stiffness with the clay packing density minimizes the anisotropy of the Biot pore pressure coefficients; whereas the intrinsic anisotropy of the elementary particle translates into a pronounced anisotropy of the Skempton coefficients. This new microporoelasticity model depends only on two shale-specific material parameters which neatly summarize clay mineralogy and bulk density, and which makes the model most appealing for quantitative geomechanics, geophysics and exploitation engineering applications.

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“…The parameter 'A' models the condition that, after some critical porosity (ranges from 0.4 to 0.5) of the rock the bulk modulus must vanish (Krief et al 1990;Goldberg and Gurevich 1998 Han et al (1986), Santos et al (2004) calculated their empirical values as 2 and 0.5. For closed relation between capillary pressure and saturation of the wetting fluid, we follow Van Genuchten model (1980).…”

Section: Numerical Resultsmentioning

confidence: 99%

Body Waves in Composite Solid Matrix Containing Two Immiscible Fluids

2015

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The present paper is concerned with the propagation of plane waves in a porous medium composed of two solids and two immiscible fluids. Using the principal of virtual complementary work, the expression for complementary strain energy density has been derived and the stress-strain relations for isotropic porous medium are obtained. The capillary pressure arising due to the pressure difference at the interface of two fluid phases has been taken into account, and the solid phases are assumed to be weakly coupled. The idea of compressibility tests is used to find values of the coefficients occurring into the stress-strain relations in terms of the physical properties of individual solid and fluid phases. The equations of motion are obtained using Lagrangian approach, and it has been shown that there may exist four compressional and two shear waves in the medium. Phase speeds of these waves are computed numerically and their dependence on frequency has been depicted graphically.

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The effects of porosity and clay content on wave velocities in sandstones

Cited by 406 publications

References 3 publications

Joint elastic-electrical properties of sediments in the Yellow Sea

Joint elastic-electrical properties of sediments in the Yellow Sea

The effect of the nanogranular nature of shale on their poroelastic behavior

Body Waves in Composite Solid Matrix Containing Two Immiscible Fluids

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