Shear wave velocity and attenuation from pulse‐echo studies of Berea sandstone

Green, Douglas H.; Wang, Herbert F.

doi:10.1029/94jb00506

Cited by 11 publications

(8 citation statements)

References 45 publications

(55 reference statements)

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“…This model was reduced to Gassmann's theory under zero dead volume condition. Furthermore, various ultrasonic results have shown that shear modulus does not always remain constant after fluid saturation as predicted by Gassmann's theory (Baechle et al, 2009;Green & Wang, 1994;Vialle & Vanorio, 2011). The variation of shear modulus for a fluid-saturated rock, either a net increase (strengthening) or a net decrease (weakening), has been attributed to the combined effect of several factors, such as fluid-solid interaction, clay degradation or expansion, and viscous coupling (Cadoret, 1993;Diethart-Jauk & Gegenhuber, 2018;Khazanehdari & Sothcott, 2003;Tutuncu & Sharma, 1992).…”

Section: Introductionmentioning

confidence: 99%

Fluid Substitution and Shear Weakening in Clay‐Bearing Sandstone at Seismic Frequencies

et al. 2019

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Using the forced oscillation method and the ultrasonic transmission method, we measure the elastic moduli of a clay‐bearing Thüringen sandstone under dry and water‐saturated conditions in a broad frequency band at [0.004–10, 106] Hz for different differential pressures up to 30 MPa. Under water‐saturated condition, clear dispersion and attenuation for Young's modulus, Poisson's ratio, and Bulk modulus are observed at seismic frequencies, except for shear modulus. The measured dispersion and attenuation are mainly attributed to the drained/undrained transition, which considers the experimentally undrained boundary condition. Gassmann's predictions are consistent with the measured undrained bulk moduli but not with the shear moduli. Clear shear weakening is observed, and this water‐softening effect is stronger at seismic frequencies than at ultrasonic frequencies where stiffening effect related to squirt flow may mask real shear weakening. The reduction in surface free energy due to chemical interaction between pore fluid and rock frame, which is not taken into account by Gassmann's theory, is the main reason for the departure from Gassmann's predictions, especially for this rock containing a large number of clay minerals.

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Section: Introductionmentioning

confidence: 99%

Fluid Substitution and Shear Weakening in Clay‐Bearing Sandstone at Seismic Frequencies

et al. 2019

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“…Four consecutive cycles of hydrate formation and dissociation allowed us to form uniform hydrate distributions (Choi et al., 2014; Spangenberg et al., 2015). The differential pressure (confining minus pore pressure) affects elastic wave properties (e.g., Green & Wang, 1994; Prasad & Manghnani, 1997). So, when pore pressure changed during hydrate formation or dissociation, we changed the confining pressure accordingly to maintain a constant differential pressure in each cycle.…”

Section: Laboratory Experimentsmentioning

confidence: 99%

The Influence of Gas Hydrate Morphology on Reservoir Permeability and Geophysical Shear Wave Remote Sensing

Sahoo

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2021

JGR Solid Earth

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Vast amounts of methane, a potent greenhouse gas, are trapped in natural methane hydrate deposits that are also highly sensitive to global warming. Methane is 84 times more potent per unit mass as a greenhouse gas than carbon dioxide over a 20-year timeframe and 25 times more potent over a century (IPCC, 2013). Methane hydrate is an ice like solid composed of water and methane that is stable under a narrow range of low temperature and moderate subsurface pressure conditions. Methane hydrate is found in large quantities globally in sub-seafloor sediments on continental margins where temperatures are below 5°C and water depths exceeds 300 m, and in permafrost regions. Huge methane emissions have been observed worldwide (Ruppel & Kessler, 2017); those due to gas hydrate dissociation have been linked to past and current climate change (Archer et al., 2009). Gas hydrate may become a viable option for carbon dioxide sequestration in future and is also being considered as a potential energy resource (Boswell & Collett, 2011).

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“…French et al (2016) give 10 −14 and 10 −13 m 2 for the permeabilities of the two sandstones. The diffusivity is given by c = kγ / νS where k is the permeability, γ is the weight density of water (9.81 × 10 4 Pa), ν is the dynamic viscosity of water (10 −3 Pa s), and S is a storage coefficient, equal to 1.5 × 10 −6 m −1 (Green & Wang, 1994). These values give

c = 0.065

m 2 /s for Berea.…”

Section: Parameter Valuesmentioning

confidence: 99%

“…This gives

P_{\infty}^{0} = 0.2

. Using

v_{s} = 2.5 \times 1 0^{3}

m/s (Green & Wang, 1994) and

G = 1 0^{4}

MPa gives

\overset{η}{true} \approx 1 0^{- 8}

. Pore pressure rates vary from 0.3 to 1.0 MPa/min.…”

Section: Parameter Valuesmentioning

confidence: 99%

Effect of Pressure Rate on Rate and State Frictional Slip

Rudnicki

Zhan

2020

Geophysical Research Letters

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This paper analyzes the effects of pore pressure rate for a spring-block system that is a simple model of a laboratory experiment. Pore pressure is increased at a constant rate in a remote reservoir, and slip is governed by rate and state friction. The frequency of rapid slip events increases with the increase of a nondimensional pressure rate that is the ratio of the time scale of frictional sliding to that for pressure increase. As the pressure rate increases, the more rapid increase of pore pressure on the slip surface quickly stabilizes slip events due to rate and state friction. Rate and state and pressure rate effects interact in a limited range of pressure rate and diffusivity. This range includes pressure rates and diffusivities representative of recent laboratory experiments. Plain Language Summary Recent field observations have identified fluid injection as an important factor in causing the dramatic increase of earthquakes in the central United States, and recent laboratory experiments have observed effects of fluid pressure rate on frictional sliding. This paper studies a simple model of a laboratory experiment: a block resting on a frictional surface and pulled by a spring. The frictional resistance to sliding depends on the rate and history of sliding. Fluid pressure is increased at a constant rate at a distance remote from the surface. The paper calculates the types and characteristics of rapid slip events and their dependence on the pressure rate and how fast fluid can diffuse from the reservoir to the frictional surface.

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Shear wave velocity and attenuation from pulse‐echo studies of Berea sandstone

Cited by 11 publications

References 45 publications

Fluid Substitution and Shear Weakening in Clay‐Bearing Sandstone at Seismic Frequencies

Fluid Substitution and Shear Weakening in Clay‐Bearing Sandstone at Seismic Frequencies

The Influence of Gas Hydrate Morphology on Reservoir Permeability and Geophysical Shear Wave Remote Sensing

Effect of Pressure Rate on Rate and State Frictional Slip

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