A numerical heat flow model for analyzing in situ data of a new device for marine gas hydrate detection and stability determination (HDSD).

Schneider von Deimling, Jens (2004) A numerical heat flow model for analyzing in situ data of a new device for marine gas hydrate detection and stability determination (HDSD). (Diploma thesis), Christian-Albrechts-Universität, Kiel, 68 pp.

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Abstract

In 2001 a new marine device for in situ Hydrate Detection and Stability
Determination (HDSD) was developed at the GEOMAR Research Center
for Marine Earth Science (Germany, Kiel). This device is capable to detect
even small amounts of gas hydrates, that would have been dissociated
during conventional recovery (depressurization, warming). In order to detect
hydrate the HDSD heats surficial sediments (0-1 m below seafloor)
to dissociate all possibly existing hydrate fractions. The freshening effect
of dissociated hydrates causes an increase of electrical resistivity measured
by HDSD and thus theoretically enables in situ quantification of gas hydrates.
Furthermore, HDSD’s temperature logging offers a means to detect
hydrates and to determine their dissociation temperature.
The aim of this study is to explore possible fields of application of the
HDSD. For this purpose numerical models are developed to better constrain
the heating process of the HDSD and the resulting temperatures.
Comparing measured and modeled data reveals that temperature is
controlled not only by simple heat conduction in sediment but also by phase
transition processes and by some side effects resulting from the device.
Explicitly modeling phase transitions indicates to what extent temperature
anomalies in the HDSD data are expected to rise in case of dissociation and
clarifies whether or not the dissociation temperature may be determined
by the HDSD.
Modeling suggests, that the HDSD in its current configuration is adapted
to be deployed in mid water depths (ca. 600 m). Larger depths constrain
higher dissociation temperatures that can not be reached due to limited
power supply. But, slight modifications in the design of the HDSD could
significantly improve the efficiency of heating and therefore its field of applicability.

Document Type: Thesis (Diploma thesis)
Thesis Advisor: UNSPECIFIED
Keywords: gas, hydrate, HDSD,
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Date Deposited: 25 Sep 2012 08:03
Last Modified: 25 Sep 2012 09:39
URI: http://oceanrep.geomar.de/id/eprint/15097

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