<i>Q</i> measurements from compressional seismic waves in unconsolidated sediments

Badri, Mohammed; Mooney, Harold M.

doi:10.1190/1.1442344

Cited by 59 publications

(36 citation statements)

References 6 publications

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“…Existing methods of estimating attenuation from VSP data include the spectral ratio method [ Gladwin and Stacey , 1974], the amplitude‐decay method [ Badri and Mooney , 1987], the risetime method [ Gladwin and Stacey , 1974], the centroid frequency shift method [ Quan and Harris , 1997], wavelet modeling [ Jannsen et al , 1985], the pulse‐broadening method [ Hatherly , 1986], and the inversion method [ Amundsen and Rune , 1994]. Tonn [1991] compared 10 methods of attenuation estimation based on the investigation of VSP seismograms and concluded that no single method is suitable for all cases.…”

Section: Estimating Attenuationmentioning

confidence: 99%

Seismic wave attenuation in methane hydrate‐bearing sediments: Vertical seismic profiling data from the Nankai Trough exploratory well, offshore Tokai, central Japan

Matsushima

2006

J. Geophys. Res.

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[1] Data from two vertical seismic profiles (VSPs) from the Nankai Trough exploratory well, offshore Tokai, central Japan, are used to estimate compressional attenuation in methane hydrate (MH)-bearing sediments at seismic frequencies of 30-110 Hz. We compare spectral ratio and centroid frequency shift methods for measuring attenuation. To isolate intrinsic attenuation from total attenuation, attenuation is computed from multiples using one-dimensional synthetic VSP data from sonic and density logs. The use of two different measurement methods and two VSPs recorded at just 100 m separation provides an opportunity to validate the attenuation measurements. No significant compressional attenuation was observed in MH-bearing sediments at seismic frequencies. Macroscopically, the peaks of highest attenuation in the seismic frequency range correspond to low-saturation gas zones. In contrast, high compressional attenuation zones in the sonic frequency range (10-20 kHz) are affected by the presence of methane hydrates in the same well locations. Thus this study demonstrated the frequency dependence of attenuation in MH-bearing sediments; MH-bearing sediments cause attenuation in the sonic frequency range rather than the seismic frequency range.Citation: Matsushima, J. (2006), Seismic wave attenuation in methane hydrate-bearing sediments: Vertical seismic profiling data from the Nankai Trough exploratory well, offshore Tokai, central Japan,

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Section: Estimating Attenuationmentioning

confidence: 99%

Seismic wave attenuation in methane hydrate‐bearing sediments: Vertical seismic profiling data from the Nankai Trough exploratory well, offshore Tokai, central Japan

Matsushima

2006

J. Geophys. Res.

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“…The seismic quality factor (Q), the inverse of seismic attenuation, can be estimated from the seismic data set using different methods, which include the amplitude decay method (Badri and Mooney, 1987), the rise time method (Gladwin and Stacey, 1974), the centroid frequency shift method (Quan and Harris, 1997), wavelet modeling (Jannsen et al, 1985), the pulse broadening method (Hatherly, 1986), the spectral ratio (SR) method (Båth, 1982;Jannsen et al, 1985), and the inversion method (Amundsen and Mittet, 1994). Tonn (1991) compares 10 methods of attenuation estimation using VSP seismograms and concludes that no single method is suitable for all situations.…”

Section: Introductionmentioning

confidence: 99%

Gas hydrate and free gas detection using seismic quality factor estimates from high-resolution P-cable 3D seismic data

et al. 2016

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We have estimated the seismic attenuation in gas hydrate and free-gas-bearing sediments from high-resolution P-cable 3D seismic data from the Vestnesa Ridge on the Arctic continental margin of Svalbard. P-cable data have a broad bandwidth (20-300 Hz), which is extremely advantageous in estimating seismic attenuation in a medium. The seismic quality factor (Q), the inverse of seismic attenuation, is estimated from the seismic data set using the centroid frequency shift and spectral ratio (SR) methods. The centroid frequency shift method establishes a relationship between the change in the centroid frequency of an amplitude spectrum and the Q value of a medium. The SR method estimates the Q value of a medium by studying the differential decay of different frequencies. The broad bandwidth and short offset characteristics of the P-cable data set are useful to continuously map the Q for different layers throughout the 3D seismic volume. The centroid frequency shift method is found to be relatively more stable than the SR method. Q values estimated using these two methods are in concordance with each other. The Q data document attenuation anomalies in the layers in the gas hydrate stability zone above the bottom-simulating reflection (BSR) and in the free gas zone below. Changes in the attenuation anomalies correlate with small-scale fault systems in the Vestnesa Ridge suggesting a strong structural control on the distribution of free gas and gas hydrates in the region. We argued that high and spatially limited Q anomalies in the layer above the BSR indicate the presence of gas hydrates in marine sediments in this setting. Hence, our workflow to analyze Q using high-resolution P-cable 3D seismic data with a large bandwidth could be a potential technique to detect and directly map the distribution of gas hydrates in marine sediments.

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“…Hatherly (1986) used seismic refraction data to measure shallow absorption by examining the variation of seismic pulse width with distance. Badri and Mooney (1987) measured absorption in near-surface unconsolidated sediments and then estimated Q by three different methods, although the results were inconclusive. Brzostowski and McMechan (1992) performed tomographic imaging of nearsurface absorption by using surface seismic data.…”

Section: Introductionmentioning

confidence: 95%