Relationship between compressional and shear‐wave velocities in classic silicate rocks

Castagna, John P.; Batzle, Michael; Eastwood, Raymond L.

doi:10.1190/1.1894108

Cited by 10 publications

(9 citation statements)

References 4 publications

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“…The results show that increasing porosity or clay content increases Vp IV s and that the velocity ratio is more sensitive to porosity changes, in agreement with the results of Costagna et al (1985). Sandstones with high clay content have velocity ratios and Poisson's ratios similar to earbonate roeks.…”

Section: Compressional Velocity Vp and Shear Velocitysupporting

confidence: 88%

“…Finally, Costagna et al (1985) found that shear velocity is nearly linearly related to eompressional velocity for water saturated elastic silieate sedimentary roeks by the equation…”

Section: Compressional Velocity Vp and Shear Velocitymentioning

confidence: 99%

“…Domenico, 1984;Rafavich et al, 1984;Costagna et al, 1985). Domenico, 1984;Rafavich et al, 1984;Costagna et al, 1985).…”

Section: Compressional Velocity Vp and Shear Velocityunclassified

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Seismic Tomography

1987

185

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Section: Compressional Velocity Vp and Shear Velocitysupporting

confidence: 88%

“…Finally, Costagna et al (1985) found that shear velocity is nearly linearly related to eompressional velocity for water saturated elastic silieate sedimentary roeks by the equation…”

Section: Compressional Velocity Vp and Shear Velocitymentioning

confidence: 99%

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Seismic Tomography

1987

185

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“…The empirical formula that connects the shear velocity V s to the compressional velocity (Castagna et al 1985) is where the velocities are in m s −1 .…”

Section: Models Of Variation Of Elastic Properties With Depth In Mamentioning

confidence: 99%

On the compliance method and the assessment of three-dimensional seafloor gas hydrate deposits

Latychev¹,

Edwards²

2003

Geophysical Journal International

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S U M M A R YMarine gas hydrates, prevalent in offshore sediments in Canada and Japan, are a possible hydrocarbon resource, a hazard to drilling and the source of a major greenhouse gas. Quantitative estimates of hydrate concentrations in deep sea sediment are difficult to obtain by conventional methods. Our group has sought novel techniques specifically designed for assessment such as the compliance method where ocean surface gravity waves are used as a source. Compliance is the transfer function between the vertical displacement of the seafloor and the corresponding pressure expressed as a function of wavelength. It is sensitive to the elastic parameters of the underlying sediments, particularly the shear modulus which is probably increased in zones containing hydrate due to cementation.Our group has demonstrated a connection between a compliance measurement and the amount of hydrate present in the hydrate stability zone for layered models. Here, we develop a 3-D numerical finite-difference code using control volume discretization to predict the compliance response over non-layered structures. Among the features of the algorithm are an ability to handle sharp contrasts in elastic moduli with a low usage of computer memory. The compliance 'anomaly' over such structures has a signature and resolution not unlike the corresponding gravity anomaly. The average response over heterogeneous structures is sensitive to the bulk hydrate content but not the connectivity pattern. Gravity waves with different polarizations crossing markedly anisotropic structures produce statistically the same average stiffness value.

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“…However, previous studies also revealed that the measured velocities of conventional rocks (that is, the rocks are not hydrate-bearing) do not always follow the time-average equation. The reason for this includes: the rocks are unconsolidated or slightly cemented, the rocks contain a lot of mud, or contain secondary pores [10] .…”

Section: Introductionmentioning

confidence: 99%

Physical Modeling for Rock Physical Properties of Natural Gas Hydrate

Zhao

Guo

Hao

et al. 2005

Chinese J. Geophys.

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Based on three types of micro models (suspended, grain contact and cemented) of hydrate‐bearing sediments, we made a set of high‐porosity, slightly cemented, unconsolidated synthetic rock samples, and 3D physical models with fillings of variable grains. The sensitivity of rock physical properties of natural gas hydrates was studied. Experiments show that the velocity of sonic waves is sensitive to pore fluid in sediments of slightly cemented or low effective pressure. As temperature decreases, grains weld which results in changes of rock physical properties of sediments, velocity, elastic moduli and frequency increase, attenuation and Vp/Vs decrease, and reflections blank.

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Relationship between compressional and shear‐wave velocities in classic silicate rocks

Cited by 10 publications

References 4 publications

Seismic Tomography

Seismic Tomography

On the compliance method and the assessment of three-dimensional seafloor gas hydrate deposits

Physical Modeling for Rock Physical Properties of Natural Gas Hydrate

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