Squirt flow influence on sonic log parameters

Markova, I.; Jarillo, G. Ronquillo; Markov, M.; Gurevich, Boris

doi:10.1093/gji/ggt442

Cited by 13 publications

(4 citation statements)

References 25 publications

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“…The V p /V s response is sensitive to changes in saturation (Brantut & David, 2018; Hamada, 2004), since fluid‐filled pores increase the bulk modulus and density of a porous material but not the shear modulus. This effect can be frequency‐dependent (Biot, 1956a, 1956b), resulting in squirt flow (Markova et al., 2014). The V p increase can be dramatic in unconsolidated sands, where V p can rise rapidly from 100s of m/s to ∼1,500 m/s as full saturation is approached (Bachrach & Nur, 1998; Gregory, 1976; Liu & Zhao, 2015; Nur & Simmons, 1969).…”

Section: Discussionmentioning

confidence: 99%

Low V_p/V_s Values as an Indicator for Fractures in the Critical Zone

Flinchum,

Grana,

Carr

et al. 2024

Geophysical Research Letters

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Poisson's ratio for earth materials is usually assumed to be positive (Vp/Vs > 1.4). However, this assumption may not be valid in the critical zone because near Earth's surface effective pressures are low (<1 MPa), porosity has a wide range (0%–60%), there are significant texture changes (e.g., unconsolidated vs. fractured media), and saturation ranges from 0% to 100%. We present P‐wave (Vp) and S‐wave (Vs) velocities from seismic refraction profiles collected in weathered crystalline environments in South Carolina and Wyoming. Our data show that ∼20% of the subsurface has negative Poisson's ratios (Vp/Vs values < 1.4), a conclusion supported by borehole sonic logs. The low Vp/Vs values are confined to the fractured bedrock and saprolite. Our data support the hypothesis that weathering‐generated microcracks can produce a negative Poisson's ratio and that Vp/Vs values can thus provide insight into important critical zone weathering processes.

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Section: Discussionmentioning

confidence: 99%

Low V_p/V_s Values as an Indicator for Fractures in the Critical Zone

Flinchum,

Grana,

Carr

et al. 2024

Geophysical Research Letters

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“…声波在井孔中的传播是声学测井的物理基础, 能否获取准确的地层信息, 关键在于理论分析得到孔隙介质井孔声场与实际情况是否相符. 以往基于 Biot 理论的井孔声场理论未考虑孔隙流体粘性应力及地层非均质性的影响, 存在一定的误差 [35][36] . 本节根据 VEB 理论, 推导了含粘性流体的孔隙介质地层中单极子源井孔声场的解析解, 并研究了非均匀孔隙介质中井孔模式波及全波波形的特征.…”

Section: 非均匀孔隙地层井孔声场unclassified

Propagation of acoustic wave and analysis of borehole acoustic field in porous medium of heterogeneous viscous fluid

Peng¹,

Zhang²,

Liu³

et al. 2023

Acta Phys. Sin.

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Sound field in fluid-saturated porous media is closely related to the viscosity of fluid and the heterogeneity of porous media. In order to improve the physical mechanism of wave propagation in porous media and expand its application in borehole acoustic field, the shear stress of porous fluid and the heterogeneity of pore structure are considered. The wave theory in porous media containing viscous fluid is deduced based on the Biot theory. The influence of porous media parameters on slow shear wave is analyzed, and the dispersion and attenuation of elastic wave caused by shear stress balance in porous fluid under the influence of inhomogeneous pore structure are studied. The analytical solution of borehole acoustic field in porous media containing viscous fluid is further derived, the phase velocity and attenuation of borehole mode waves in heterogeneous porous media and the waveform of borehole full wave are calculated, and the influence of pore fluid viscosity on borehole full wave is analyzed. The results show that there are slow shear waves in the porous media containing viscous fluid. The slow shear wave is characterized by low velocity and large attenuation. In heterogeneous porous media, the balance process of shear stress related to slow shear wave not only leads to the dispersion and attenuation of fast P-wave, but also affects the propagation characteristics of borehole pseudo Rayleigh wave and Stoneley wave. In addition, the pore fluid viscosity has a great influence on the borehole Stoneley wave. The work of this paper improves the physical mechanism of acoustic wave propagation in porous media and provides theoretical guidance for the interpretation and application of borehole acoustic waves in porous formations.

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“…where P 0 is the acoustic pressure amplitude of the source; S(ω) is the frequency spectrum of the source; J 0 (k f r r ) is the Bessel function of order 0; H (1) 0 (k f r r ) is the Hankel function of the first kind and order 0; k f r and k z are the components of the wave vector in the radial and tangential directions, respectively; r 0 is the borehole radius; the coefficient X is determined in the process of the solution of the problem of dynamical theory of poroelasticity. The solution details are presented in Markova et al (2014).…”

Section: Figurementioning

confidence: 99%

“…In the case of axisymmetric oscillations a zero-order guided wave is named as the Stoneley wave (Paillet and Cheng 1991;Tang and Cheng 2004). * E-mails: mmarkov@imp.mx, mikmarkov@gmail.com In a typical high-velocity formation (v s > v f , where v s and v f are the velocities of the shear wave in the rock and of the compressional wave in the borehole fluid, respectively), the wave field generated by a monopole source of acoustic oscillations is formed by the waves of four types: body wavescompressional wave (P) and shear wave (S) and guided waves -the Stoneley wave and pseudo-Rayleigh waves (Cheng and Toksöz 1981;Krutin, Markov and Yumatov 1988;Sharma and Gogna 1990;Markova et al 2014). In a low-velocity formation (v s < v f ), instead of the pseudo-Rayleigh waves guided waves of another type (leaky waves), are generated (Paillet and Cheng 1991;Tang and Cheng 2004).…”

Section: Introductionmentioning

confidence: 99%

Energy of acoustic signals in a borehole

Markova

Jarillo

Markov

2019

Geophysical Prospecting

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In the present article, the dependencies of the acoustic signal total energy and the energies of the wave packets of different types of the waves on the elastic parameters and permeability of rocks have been studied. We have considered traditional logging tools containing acoustical monopole source. Calculations were performed in a frequency range of dozens of kilohertz, typical for acoustic well logging. It was shown that in a typical high‐velocity formation (vs > vf, where vs and vf are the velocities of the shear wave in the rock and of the compressional wave in the borehole fluid, respectively), the pseudo‐Rayleigh waves, whose elastic properties depend mainly on the shear modulus of the rock, contributed significant energy to the total signal energy in the borehole. The energies of different wave packets depend on the permeability in different ways. The greatest sensitivity to permeability change has been shown by the acoustic signal total energy and the energy of the low‐velocity part of the pseudo‐Rayleigh wave packet. The theoretical analysis was illustrated by real sonic log data.

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Squirt flow influence on sonic log parameters

Cited by 13 publications

References 25 publications

Low V_p/V_s Values as an Indicator for Fractures in the Critical Zone

Low V_p/V_s Values as an Indicator for Fractures in the Critical Zone

Propagation of acoustic wave and analysis of borehole acoustic field in porous medium of heterogeneous viscous fluid

Energy of acoustic signals in a borehole

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Squirt flow influence on sonic log parameters

Cited by 13 publications

References 25 publications

Low Vp/Vs Values as an Indicator for Fractures in the Critical Zone

Low Vp/Vs Values as an Indicator for Fractures in the Critical Zone

Propagation of acoustic wave and analysis of borehole acoustic field in porous medium of heterogeneous viscous fluid

Energy of acoustic signals in a borehole

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Low V_p/V_s Values as an Indicator for Fractures in the Critical Zone

Low V_p/V_s Values as an Indicator for Fractures in the Critical Zone