Marine Biogeochemistry

Subproject A3- Autoclave Drilling

The "Meeresboden-Bohrgerät" (MeBo) is a portable sea floor dilling rig, wich is lowered to the sea bed with a steel armoured umbilical and operated remotely the vessel.

In the frame of subproject A3 drilling tools are to be equipped with autoclave technology and used for sampling of hydrate deposits.

To evaluate the quality of gas hydrate deposits, while considering hydrate distribution and concentration to be determined within the occurrences, application of drilling technology is essential. Since gas hydrates decompose while decompressed or heated during drilling and the gas released is lost, a combined autoclave drilling technology is necessary to preserve the in situ pressure. Using this approach accurate quantification of gas hydrate is possible.

Methods
Drilling Technology 

Two lines of development using autoclave technology, which allow for recovery of gas hydrate bearing drilling cores under in situ pressure, are pursued in the framework of SUGAR. The lines aim on different operating conditions.

In the first line an autoclave technology is to be developed and integrated into the transportable sea floor drill rig (MeBo) developed at the MARUM in Bremen. The MeBo, which can be launched from conventional ships without boring platform into water depths of up to 2000 m, is used to recover cores from unconsolidated sediments and rocks of 50 m length, so far.

The second line aims on the development of an autoclave system with associated drilling technology, for sampling of soft sediments and gas hydrates. This system is not limited with respect to water depth and thickness of sediments to be sampled. The employment of this system will be restricted to drilling ships.

Both approaches provide new technologies, which can be adapted to specific conditions and requirements of sediments to be drilled during gas hydrate sampling.

Autoclave Technology

A prerequisite for investigations of natural gas hydrates under in situ conditions, is the maintenance of pressure and temperature conditions as present at and within the seafloor during recovery. The processing of pressure cores after recovery includes:

  • Non-destructive visualization of the sediment by means of computer tomographic visualization
  • Controlled gas release for quantification of the natural gas inventory
  • Sampling of the gas released for subsequent analyses

Literatur

Abegg, F., Hohnberg, H.J., Pape, T., Bohrmann, G. & Freitag, J.

Development and application of pressure-core-sampling systems for the investigation of gas- and gas-hydrate-bearing sediments

2008

Deep-Sea Research Part I-Oceanographic Research Papers
Vol. 55(11), pp. 1590-1599 

article

DOI  

Dickens, G.R., Paull, C.K. & Wallace, P.

Direct measurement of in situ methane quantities in a large gas-hydrate reservoir

1997

Nature
Vol. 385(6615), pp. 426-428 

article

 

Heeschen, K., Haeckel, M., Hohnberg, H.-J., Abegg, F. & Bohrmann, G.

Pressure coring at gas hydrate-bearing sites in the eastern Black Sea off Georgia

2007

Geophysical Research Abstracts
Vol. 9(03078) 

article

URL 

Heeschen, K.U., Hohnberg, H.J., Haeckel, M., Abegg, F., Drews, M. & Bohrmann, G.

In situ hydrocarbon concentrations from pressurized cores in surface sediments, Northern Gulf of Mexico

2007

Marine Chemistry
Vol. 107(4), pp. 498-515 

article

DOI

Contact

Center for Marine Environmental Sciences MARUM
www.marum.de

Coordination:

Prof. Dr. Gerhard Bohrmann
Tel.: +49 421-218-65050
Fax: +49 421-218-8664
gbohrmann(at)marum.de

Staff:

Dr. Tim Freudenthal
Tel.: +49 421-218-65602
Fax: +49 421-218-65505
freuden(at)marum.de

Dr. Thomas Pape
Tel.: +49 421-218-65053
Fax: +49 421-218-8664
tpape(at)marum.de

Prakla Bohrtechnik GmbH
www.prakla-bohrtechnik.de

Prof. Dr. Reiner Homrighausen
Tel.: +49 5171 90550 
Fax: +49 431 600 2922
homrighausen(at)gwe-gruppe.de

Dr. Hans-Otto Könnecker
Tel.: +49 5171 9055 200
Fax: +49 431 600 2922
h-o.koennecker(at)prakla-bohrtechnik.de

Clausthal University of Technology, Institute of Petroleum Engineering
www.ite.tu-clausthal.de

Giorgi Phochkhua
Tel.: +49 5323 72 2889
Fax: +49 5353 72 3146
giorgi.phochkhua(at)tu-clausthal.de

Prof. Dr. Kurt M. Reinicke
Tel.: +49 5323 72 2240
Fax: +49 5323 72 3146
kurt.m.reinicke(at)tu-clausthal.de