Stress-Associated Intrinsic and Scattering Attenuation from Laboratory Ultrasonic Measurements on Shales

Hu, Junhua; Fu, Li‐Yun; Wei, Wei; Zhang, Yan

doi:10.1007/s00024-017-1705-9

Cited by 11 publications

(3 citation statements)

References 97 publications

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“…The triaxial compaction cell allows for measurements of ultrasonic properties (P‐ and S‐wave velocities along the symmetry axial direction) of the cylindrical rock samples, through applying the typical pulse‐transmission technique and combining with the length of tested sample. Conceptually, our setup is comparable with the apparatus at University of Chinese Academy of Sciences (Cheng et al., 2019; Hu et al., 2017) with few modifications that allow for independent control of axial, radial and pore pressure using a triaxial high‐pressure cell, which allows axial loading up to 130 MPa, with a pore pressure of 20 MPa and a confining pressure of 80 MPa; the temperature range can be regulated between −20°C and 110°C. A schematic diagram and a photograph of the apparatus for ultrasonic measurement are shown in Figure 4.…”

Section: Laboratory Ultrasonic Experiments and Observationsmentioning

confidence: 99%

Laboratory experiments and theoretical study of pressure and fluid influences on acoustic response in tight rocks with pore microstructure

He,

Wang,

et al. 2024

Geophysical Prospecting

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Wave‐induced fluid flow is considered to be a major source of seismic attenuation and dispersion in porous rocks. From the physical description of partially saturated reservoirs, numerous analytical solutions based on upscaling homogenization theories have been employed to calculate equivalent frequency‐dependent poroelastic media. Nevertheless, dispersion and attenuation predictions are often not reasonably consistent with laboratory and field measurements in a broad frequency range, particularly due to influences of biphasic fluids and their distribution, presence of heterogeneities on various length scales, and pore microstructure. We investigate the role of pore microstructure on pressure and fluid saturation dependence of elastic velocities in tight sandstones. Previous work points out that differentiating the impacts of heterogeneities at various scales on dispersion within seismic exploration and sonic frequencies can be very difficult. In practice, this is because fluid‐related dispersion mechanisms are impossible to be independent. Thus, it is important for a theoretical and more quantitative analysis of the relative contribution of interrelated energy dissipation processes through a better understanding of combined influences due to the presence of microscopic and mesoscopic heterogeneities. Based on microscopic squirt flow and mesoscopic flow in a partially saturated medium, we develop a poroelastic model that allows evaluating the overall frequency‐dependent dispersion via considering a random distribution of fluid heterogeneities as well as the broadly distributed aspect ratio of compliant pores. Experimental validation of the model is accomplished via a comprehensive comparison of predictions with measurements of partially saturated velocities versus pressure and fluid for sandstones with specific pore microstructures.This article is protected by copyright. All rights reserved

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Section: Laboratory Ultrasonic Experiments and Observationsmentioning

confidence: 99%

Laboratory experiments and theoretical study of pressure and fluid influences on acoustic response in tight rocks with pore microstructure

He,

Wang,

et al. 2024

Geophysical Prospecting

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“…Much experimental work on carbonates aims to determine relationships between physical and elastic properties, most often as a function of the effective stress, which also controls scattering and intrinsic attenuation as it changes the crack density and pore shape (e.g., Goodfellow et al, 2015;Guo & Fu, 2007;Guo et al, 2009;Hu et al, 2018;Wei & Fu, 2014) Many physical properties are of interest as well as how they evolve under depositional and burial conditions. Examples include pore type, porosity, fluid type and saturation, composition, and diagenetic alteration.…”

Section: Introductionmentioning

confidence: 99%

Scattering and Frequency Effects on Ultrasonic Velocities of Carbonates

Tisato,

Spikes,

Saxena

et al. 2024

Preprint

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The scattering of elastic waves (scattering) causes velocity dispersion that increases uncertainties of seismic analyses and could be misinterpreted as the result of other phenomena. One of these phenomena is the wave-induced fluid flow in saturated rocks, which comprise most of the rocks in the crust of our planet. Therefore, understanding scattering sources and distinguishing among different sources of velocity dispersion is critical to improve subsurface imaging to locate resources and understand subsurface processes. Here, we present and discuss measurements and numerical modeling of ultrasonic wave velocities in homogeneous and heterogeneous carbonate rocks with porosities between 3 and 26%. Ultrasonic velocities were measured at frequencies between 0.3 and 1 MHz, and numerical wave propagation simulations on the CT-scanned samples were performed using an elastic approximation and a finite difference method. The homogeneous sample and the corresponding numerical simulations exhibit negligible velocity dispersion. On the other hand, heterogeneous samples exhibit large dispersion, and the corresponding numerical simulations reproduce well the observed dispersion. We conclude that scattering has a first-order effect on the velocities of the elastic waves and should be considered when applying rock physics models in heterogenous carbonates similar to those studied here. e illustrate a method to characterize frequency-dependent ultrasonic velocities (i.e., dispersion) and show that finite-difference modeling can reproduce the laboratory-observed dispersion, including the typical frequency shift produced by scatterers and dispersive media.

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“…Liu et al () analyzed the difference between the relative information contained in static and dynamic seismic attributes in both dry and saturated fractured rocks. In particular, for saturated porous rock, seismic attenuation is recognized as a potentially important parameter for characterizing fracture networks (Ba et al, ; Guo, Rubino, Glubokovskikh, et al, ; Hu et al, ; Liu et al, ; Wei & Fu, ).…”

Section: Introductionmentioning

confidence: 99%

Seismic Dispersion and Attenuation in Saturated Porous Rock With Aligned Slit Cracks

Guo

et al. 2018

JGR Solid Earth

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We estimate the seismic attenuation and velocity dispersion induced by fluid pressure diffusion in a saturated porous medium containing a sparse distribution of aligned slit fractures. This is done by solving the scattering problem for a single crack and using Waterman‐Truell scattering approximation for a distribution of cracks. This approach gives a numerical solution for the entire frequency range and analytical solutions for the low‐ and high‐frequency limits. Analysis of the results shows that the characteristics of the seismic dispersion and attenuation for the slit cracks are similar to known results for penny‐shaped crack. At high frequencies, the attenuation and dispersion are controlled by the crack density regardless of the crack geometry. At low frequencies, due to the different geometries of the slit and penny‐shaped cracks, the characteristics of seismic dispersion and attenuation are different. For both the slit and penny‐shaped crack case, the slope of the frequency dependence attenuation of factor (inverse quality factor) Q−1 tends to be 1. Yet the low‐frequency asymptotic solutions for these two cases are somewhat different. For penny‐shaped cracks, the Q−1(ω) on the bilogarithmic scale has a straight line asymptote with slope 1, so that the attenuation factor at low frequencies is proportional to the frequency ω. However, for slit cracks, the asymptotic low‐frequency solution contains a logarithmic function of ω, and no such asymptote exists. At the same time, similarly to the penny‐shaped crack case, the solution for compressional velocity in the low‐frequency limit is consistent with the anisotropic Gassmann theory.

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Stress-Associated Intrinsic and Scattering Attenuation from Laboratory Ultrasonic Measurements on Shales

Cited by 11 publications

References 97 publications

Laboratory experiments and theoretical study of pressure and fluid influences on acoustic response in tight rocks with pore microstructure

Laboratory experiments and theoretical study of pressure and fluid influences on acoustic response in tight rocks with pore microstructure

Scattering and Frequency Effects on Ultrasonic Velocities of Carbonates

Seismic Dispersion and Attenuation in Saturated Porous Rock With Aligned Slit Cracks

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