The University of Southampton
University of Southampton Institutional Repository

Theoretical modeling insights into elastic wave attenuation mechanisms in marine sediments with pore-filling methane hydrate

Theoretical modeling insights into elastic wave attenuation mechanisms in marine sediments with pore-filling methane hydrate
Theoretical modeling insights into elastic wave attenuation mechanisms in marine sediments with pore-filling methane hydrate
The majority of presently exploitable marine methane hydrate reservoirs are likely to host hydrate in disseminated form in coarse grain sediments. For hydrate concentrations below 25–40%, disseminated or pore-filling hydrate does not increase elastic frame moduli, thus making impotent traditional seismic velocity-based methods. Here, we present a theoretical model to calculate frequency-dependent P and S wave velocity and attenuation of an effective porous medium composed of solid mineral grains, methane hydrate, methane gas, and water. The model considers elastic wave energy losses caused by local viscous flow both (i) between fluid inclusions in hydrate and pores and (ii) between different aspect ratio pores (created when hydrate grows); the inertial motion of the frame with respect to the pore fluid (Biot's type fluid flow); and gas bubble damping. The sole presence of pore-filling hydrate in the sediment reduces the available porosity and intrinsic permeability of the sediment affecting Biot's type attenuation at high frequencies. Our model shows that attenuation maxima due to fluid inclusions in hydrate are possible over the entire frequency range of interest to exploration seismology (1–106 Hz), depending on the aspect ratio of the inclusions, whereas maxima due to different aspect ratio pores occur only at sonic to ultrasound frequencies (104–106 Hz). This frequency response imposes further constraints on possible hydrate saturations able to reproduce broadband elastic measurements of velocity and attenuation. Our results provide a physical basis for detecting the presence and amount of pore-filling hydrate in seafloor sediments using conventional seismic surveys.
elastic wave attenuation, methane hydrate, rock physics modeling
2169-9313
1835–1847
Marín-Moreno, H.
e466cafd-bd5c-47a1-8522-e6938e7086a4
Sahoo, S.K.
6dab0376-36df-44c5-9f36-cb4a29d9b03b
Best, A.I.
f962ede8-2ff2-42b6-baa1-88d93dfb08dd
Marín-Moreno, H.
e466cafd-bd5c-47a1-8522-e6938e7086a4
Sahoo, S.K.
6dab0376-36df-44c5-9f36-cb4a29d9b03b
Best, A.I.
f962ede8-2ff2-42b6-baa1-88d93dfb08dd

Marín-Moreno, H., Sahoo, S.K. and Best, A.I. (2017) Theoretical modeling insights into elastic wave attenuation mechanisms in marine sediments with pore-filling methane hydrate. Journal of Geophysical Research: Solid Earth, 122 (3), 1835–1847. (doi:10.1002/2016JB013577).

Record type: Article

Abstract

The majority of presently exploitable marine methane hydrate reservoirs are likely to host hydrate in disseminated form in coarse grain sediments. For hydrate concentrations below 25–40%, disseminated or pore-filling hydrate does not increase elastic frame moduli, thus making impotent traditional seismic velocity-based methods. Here, we present a theoretical model to calculate frequency-dependent P and S wave velocity and attenuation of an effective porous medium composed of solid mineral grains, methane hydrate, methane gas, and water. The model considers elastic wave energy losses caused by local viscous flow both (i) between fluid inclusions in hydrate and pores and (ii) between different aspect ratio pores (created when hydrate grows); the inertial motion of the frame with respect to the pore fluid (Biot's type fluid flow); and gas bubble damping. The sole presence of pore-filling hydrate in the sediment reduces the available porosity and intrinsic permeability of the sediment affecting Biot's type attenuation at high frequencies. Our model shows that attenuation maxima due to fluid inclusions in hydrate are possible over the entire frequency range of interest to exploration seismology (1–106 Hz), depending on the aspect ratio of the inclusions, whereas maxima due to different aspect ratio pores occur only at sonic to ultrasound frequencies (104–106 Hz). This frequency response imposes further constraints on possible hydrate saturations able to reproduce broadband elastic measurements of velocity and attenuation. Our results provide a physical basis for detecting the presence and amount of pore-filling hydrate in seafloor sediments using conventional seismic surveys.

Text
Mar-n-Moreno_et_al-2017-Journal_of_Geophysical_Research__Solid_Earth - Version of Record
Available under License Other.
Download (3MB)

More information

Accepted/In Press date: 23 February 2017
e-pub ahead of print date: 15 March 2017
Additional Information: Funding Information: We acknowledge funding from the United Kingdom Natural Environment Research Council (NE/J020753/1). The data used are listed in the references, tables, figures, and in an Excel spreadsheet in the supporting information. The references Berryman []; Bishop [], Dvorkin et al. [], Hovem and Ingram []; Ishii and Mishima []; Kuster and Toksöz []; Mahabadi et al. []; Mindlin [], and Reuss [] refer only to the supporting information. We thank Nicola Tisato and an anonymous reviewer for their detailed and constructive comments.
Keywords: elastic wave attenuation, methane hydrate, rock physics modeling
Organisations: Geology & Geophysics, Marine Geoscience

Identifiers

Local EPrints ID: 406467
URI: http://eprints.soton.ac.uk/id/eprint/406467
ISSN: 2169-9313
PURE UUID: 0d1f5b6b-5c3b-41d1-9a55-069722e46b4e
ORCID for H. Marín-Moreno: ORCID iD orcid.org/0000-0002-3412-1359

Catalogue record

Date deposited: 18 Mar 2017 02:04
Last modified: 16 Mar 2024 05:09

Export record

Altmetrics

Contributors

Author: H. Marín-Moreno ORCID iD
Author: S.K. Sahoo
Author: A.I. Best

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×