The microstructure of sediment-hosted hydrates: evidence from effective medium modelling of laboratory and borehole seismic data


Minshull, T.A. and Chand, S. (2009) The microstructure of sediment-hosted hydrates: evidence from effective medium modelling of laboratory and borehole seismic data. In, Long, D., Lovell, M. A., Rees, J.G. and Rochelle, C.A. (eds.) Sediment-Hosted Gas Hydrates. London, UK, Geological Society of London, 93-101. (Geological Society of London Special Publication 319).

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Description/Abstract

Much of our knowledge of hydrate distribution in the subsurface comes from
interpretations of remote seismic measurements. A key step in such interpretations is
an effective medium theory that relates the seismic properties of a given sediment to
its hydrate content. A variety of such theories have been developed; these theories
generally give similar results if the same assumptions are made about the extent to
which hydrate contributes to the load-bearing sediment frame. We have further
developed and modified one such theory, the self-consistent
approximation/differential effective medium approach, to incorporate additional
empirical parameters describing the extent to which both the sediment matrix material
(clay or quartz) and the hydrate are load-bearing. We find that a single choice of
these parameters allows us to match well both P and S wave velocity measurements
from both laboratory and in situ datasets, and that the inferred proportion of hydrate
that is load-bearing varies approximately linearly with hydrate saturation. This
proportion appears to decrease with increasing hydrate saturation for gas-rich
laboratory environments, but increase with hydrate saturation when hydrate is formed
from solution and for an in situ example.

Item Type: Book Section
Subjects: Q Science > QE Geology
Divisions: University Structure - Pre August 2011 > School of Ocean & Earth Science (SOC/SOES)
ePrint ID: 66803
Date Deposited: 22 Jul 2009
Last Modified: 27 Mar 2014 18:47
URI: http://eprints.soton.ac.uk/id/eprint/66803

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