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| Titel |
New tools and applications for the retrieval of cores under in situ pressure |
| VerfasserIn |
M. Rothfuss, E. Anders, W. H. Müller, T. Rothenwänder, D. Wunsch |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250070457
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| Zusammenfassung |
| When a sediment sample is recovered from underground or beneath the sea floor and brought
to the surface, the initial in situ pressure is released. As a result of this depressurisation,
physical and chemical properties of the sample are significantly altered. In addition, gases
and fluids may disappear during the retrieval of the sample.
This is a critical limitation in the investigation of marine gas hydrates which decompose
rapidly under atmospheric conditions.
Various systems for the retrieval of cores under in situ pressure have been developed for
the investigation of offshore gas hydrate deposits. The systems comprise of tools for the
coring of the upper few meters of the seabed as well as wireline systems for use within the
drill string for the investigation of gas hydrates buried several hundred meters below
seabed. The Technical University Berlin (TUB) has been active in the development of
pressure coring systems for many years. The developments include coring tools as
well as systems for the transfer, sub-sampling, and analysis of cores under in situ
pressure.
All of these systems have been deployed over the last 10 years on several offshore
research cruises; from drill ships, like the IODP research vessel JOIDES Resolution, to
smaller research vessels. The expeditions yielded valuable scientific insights related to the
occurrence, distribution, and formation of gas hydrates in the seabed and how they respond to
environmental changes.
In recent years, new systems have been developed at TUB in order to increase the volume
of cores, reach greater depth, and enhance reliability.
However, there are many other fields of scientific study where the preservation of in situ
pressure and the original content of fluid and gases may be crucial for the results of the
investigation. The new fields of application consist of, but are not limited to, unconventional
energy resources like coal bed methane, shale gas and oil, tight gas and the investigation of
the deep biosphere. Also, exploration of conventional oil and gas fields may benefit from
pressurized cores.
The latest designs at TUB encompass further developments in wireline pressure corers
and a new drill string conveyed tool, which is not limited to the internal diameter of the drill
string. Both tools are suitable for deployment from land based or offshore drilling
rigs and can be adapted for specific needs in terms of pressure rating, core length
and diameter, and geological formation. In addition, a newly developed transfer
system allows for the transfer, cutting and subsequent analysis or storage of the core. |
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