Random heterogeneous model with bimodal velocity distribution for Methane Hydrate exploration

Rie Kamei, Masami Hato, Toshifumi Matsuoka

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

We have developed a random heterogeneous velocity model with bimodal distribution in methane hydrate-bearing zones. The P-wave well-log data have a von Karman type autocorrelation function and non-Gaussian distribution. The velocity histogram has two peaks separated by several hundred metres per second. A random heterogeneous medium with bimodal distribution is generated by mapping of a medium with a Gaussian probability distribution, yielded by the normal spectral-based generation method. By using an ellipsoidal autocorrelation function, the random medium also incorporates anisotropy of autocorrelation lengths. A simulated P-wave velocity log reproduces well the features of the field data. This model is applied to two simulations of elastic wave propagation. Synthetic reflection sections with source signals in two different frequency bands imply that the velocity fluctuation of the random model with bimodal distribution causes the frequency dependence of the Bottom Simulating Reflector (BSR) by affecting wave field scattering. A synthetic cross-well section suggests that the strong attenuation observed in field data might be caused by the extrinsic attenuation in scattering. We conclude that random heterogeneity with bimodal distribution is a key issue in modelling hydrate-bearing zones, and that it can explain the frequency dependence and scattering observed in seismic sections in such areas.

Original languageEnglish
Pages (from-to)41-49
Number of pages9
JournalExploration Geophysics
Volume36
Issue number1
DOIs
Publication statusPublished - 2005
Externally publishedYes

Fingerprint

hydrates
methane
velocity distribution
autocorrelation
P waves
frequency dependence
scattering
attenuation
P-wave
heterogeneous medium
elastic waves
histograms
elastic wave
reflectors
wave field
histogram
wave propagation
distribution functions
wave velocity
distribution

Keywords

  • Autocorrelation
  • Bimodal distribution
  • BSR
  • Methane hydrate
  • Random heterogeneous

ASJC Scopus subject areas

  • Geophysics
  • Geology

Cite this

Random heterogeneous model with bimodal velocity distribution for Methane Hydrate exploration. / Kamei, Rie; Hato, Masami; Matsuoka, Toshifumi.

In: Exploration Geophysics, Vol. 36, No. 1, 2005, p. 41-49.

Research output: Contribution to journalArticle

Kamei, Rie ; Hato, Masami ; Matsuoka, Toshifumi. / Random heterogeneous model with bimodal velocity distribution for Methane Hydrate exploration. In: Exploration Geophysics. 2005 ; Vol. 36, No. 1. pp. 41-49.
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