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7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
STRUCTURE AND DISTRIBUTION OF GAS HYDRATES IN MARINE
SEDIMENTS
Contribution 4, by:
F. Abegg, G. Bohrmann, GEOMAR
J. Freitag & S. Kipfstuhl, AWI
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
Introduction
• Objectives, techniques, working areas• Examples of different internal gas hydrate
structures• Quantification of gas hydrate, free gas and
host sediment• A frozen core from the Black Sea• A pressurised core from Hydrate Ridge• Conclusions
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
Tool: X-Ray CT scanner
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
Frozen gas hydrate sample in a foam box
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
Black Sea: core location
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
Hydrate Ridge: core location
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
Sample SO148-11
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
Honeycomb structure
20 mm
gas hydrate(light grey)
mud(dark grey)
carbonate(black spots)
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
Sample SO148-20
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
Dense gas hydrate
40 mm
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
Sample SO148-14
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
Alternating layers
50 mm
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
SO148-5: 3-D using 227 slices
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
SO148-5: 3-D cutout
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
Example of thresholding
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
Quantification of components
Example fromsample SO148-11
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
Frozen core from the Black Sea
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
Various analyses
3-D gas hydrate
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
MultiAutoklavCorer
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
Pressurised? YES!!
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
LabTransferChamber positioned in CT
scanner
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
Results LTC4
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
shell/carbonategas hydrategasmud
10 cm subseafloor depth 27 cm subseafloor depth 29 cm subseafloor depth
Slices from LTC4
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
2-D and 3-D
7th Shallow Gas Group MeetingBaku, Azerbaijan, 07.10. – 11.10.2002
Conclusions
• CT is an appropriate tool to quantify gas hydrate, gas and host sediment on a mm-scale and to determine internal structures
• Together with autoclave technology the above is possible close to in situ conditions
• A frozen core from the Sorokin Trough shows gas hydrates in elongated near-vertical, crack-like features
• In situ gas hydrate concentration at Hydrate Ridge reaches 50 Vol.% in a horizontal layer with a gas content of up to 10 Vol.%
• Thank you very much for your attention!
respond to:[email protected]