Testing VSP‐based Q‐estimation with spherical wave models

Haase, Arnim B.

doi:10.1190/1.2793114

Cited by 3 publications

(7 citation statements)

References 4 publications

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“…Figure 13 (Haase 2007) gives log‐magnitude spectra for the depth region of 61–1113 m, which is below that displayed in Fig. 8, again computed with .…”

Section: Modelling Resultsmentioning

confidence: 82%

“…Relative scaling is lost when applying the spectral ratio method because multipliers become added constants on taking the logarithm; these added constants are part of the neglected intercept term. Figure 8 demonstrates what the spectral ratio method sees (Haase 2007). The downgoing wave appears to gain high‐ frequency strength: the more shallow in depth the VSP‐receiver station, the steeper the slope of log‐magnitude spectra as function of frequency.…”

Section: Modelling Resultsmentioning

confidence: 99%

“…They gave an equation for the P‐wave potential caused by a point source (Weyl/Sommerfeld integral approach) in a 3D homogeneous medium. P‐wave displacements can be obtained from such potentials by computing gradients, which for the direct wave gives (Haase 2007): where u P (ω) is the P‐wave displacement along the ray at the current receiver, ω is the frequency in radians, t is the time, p is the horizontal slowness, ξ is the vertical slowness, J 0 and J 1 are zero‐order and first‐order Bessel functions of the first kind, r is the range (horizontal offset between source and receivers), z is the source‐to‐receiver depth interval (to the current receiver) and θ is the incidence angle from the vertical (at the current receiver).…”

Section: Theorymentioning

confidence: 99%

“…They gave an equation for the P-wave potential caused by a point source (Weyl/Sommerfeld integral approach) in a 3D homogeneous medium. P-wave displacements can be obtained from such potentials by computing gradients, which for the direct wave gives (Haase 2007):…”

Section: T H E O R Ymentioning

confidence: 99%

“…In pursuing the topic of stratigraphic attenuation, we recently computed synthetic vertical seismic profile data with the aid of Weyl/Sommerfeld integrals (Haase 2007). We noted some peculiar behaviour of magnitude spectra as a function of depth in near‐surface situations.…”

Section: Introductionmentioning

confidence: 99%

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Near‐field seismic effects in a homogeneous medium and their removal in vertical seismic profile attenuation estimates

Haase

Stewart

2010

Geophysical Prospecting

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A B S T R A C TTo better understand (and correct for) the factors affecting the estimation of attenuation (Q), we simulate subsurface wave propagation with the Weyl/Sommerfeld integral. The complete spherical wavefield emanating from a P-wave point source surrounded by a homogeneous, isotropic and attenuative medium is thus computed. In a resulting synthetic vertical seismic profile, we observe near-field and far-field responses and a 90 • phase rotation between them. Depth dependence of the magnitude spectra in these two depth regions is distinctly different. The logarithm of the magnitude spectra shows a linear dependence on frequency in the far-field but not in those depth regions where the near-field becomes significant. Near-field effects are one possible explanation for large positive and even negative Q-factors in the shallow section that may be estimated from real vertical seismic profile data when applying the spectral ratio method. We outline a near-field compensation technique that can reduce errors in the resultant Q estimates.

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“…Figure 13 (Haase 2007) gives log‐magnitude spectra for the depth region of 61–1113 m, which is below that displayed in Fig. 8, again computed with .…”

Section: Modelling Resultsmentioning

confidence: 82%

Section: Modelling Resultsmentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

Section: T H E O R Ymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Near‐field seismic effects in a homogeneous medium and their removal in vertical seismic profile attenuation estimates

Haase

Stewart

2010

Geophysical Prospecting

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Seismic-Derived Quality Factor for Lithology Classification around the Median Tectonic Line

Shigei¹,

Tsuji²,

Matsuoka³

et al. 2014

J. Soc. Mat. Sci., Japan

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We calculated quality factor from seismic reflection data in order to classify the lithology around the Median Tectonic Line (MTL). Since seismic velocity around the MTL was not accurately estimated, it was difficult to classify the lithology and characterize the MTL. To calculate quality factor from seismic data, we used two methods: (1) spectral ratio method and (2) peak frequency method. In this study, we applied these two methods for the multi-channel seismic reflection data as well as zero-offset Vertical Seismic Profiling (VSP) data acquired at MTL in Ehime Prefecture, Japan. The result shows that quality factor is significantly changed at the lithological boundary beneath the MTL. From the estimated quality factor, we interpret that lithological boundary beneath the MTL is dipping to north. This study further shows that quality factor can be useful seismic attribute for lithology classification, even when seismic velocity cannot be estimated.

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Modelling Near-field Effects in VSP-based Q-estimation

Haase¹,

Stewart²

2008

70th EAGE Conference and Exhibition Incorporating SPE EUROPEC 2008

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The complete spherical wavefield emanating from a P-wave point source surrounded by a homogeneous isotropic medium is computed with the aid of Sommerfeld/Weyl integrals. In a resulting synthetic VSP, we observe a near-field, a far-field and a 90° phase rotation between the two. Depth dependence of magnitude spectra in these two depth regions is distinctly different. Log magnitude spectra show a linear dependence on frequency in the far-field but not in depth regions where the near-field becomes significant. Near-field effects are one possible explanation for large positive and even negative Q-factors in the shallow section that may be estimated from VSP data when applying the spectral ratio method.

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Testing VSP‐based Q‐estimation with spherical wave models

Cited by 3 publications

References 4 publications

Near‐field seismic effects in a homogeneous medium and their removal in vertical seismic profile attenuation estimates

Near‐field seismic effects in a homogeneous medium and their removal in vertical seismic profile attenuation estimates

Seismic-Derived Quality Factor for Lithology Classification around the Median Tectonic Line

Modelling Near-field Effects in VSP-based Q-estimation

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