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7/30/2019 Gas Hydrates1
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GasHydrates
History
Why the interest?
Chemical Aspects Biology
Geology
Utilization as a Fuel Source and FutureDevelopment
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History
Discovered in late 19th centuryin Siberian permafrost
Known to form pipelineblockages for years
Rediscovered as oilexploration moved offshore inearly 1970s
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Why the sudden interest?
The fuel of the next century?
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Worldwide reserves estimated to be
400-500 million trillion cubic
feet(tcf)
5000 tcf of known natural gas
reserves worldwide
Map of in-situ hydrate locations
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USA has gas hydrate reserves
estimated between 112000 tcf and
676000 tcf USA has 1400 tcf of natural gas
reserves
USA uses 25-30 tcf/yr of natural gas
Carbon reserves vs gas hydrates
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Chemical Aspects of
Gas Hydrates
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Ice-like crystaline mineral
1 cubic meter of gas hydrate (90% siteoccupied) = 163 m3 of gas + .87 m3
Clathrates or Clathrate Hydrates
Three Structure Types: I, II, H Structure type determines gas type Scientist dont fully understand the physics
of gas hydrate formation
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Structure I Gas HydrateCrystal - Cubic Lattice
Can hold only smallmolecules (5.2 angstroms orless) such as ethane(C2H6)and methane(CH4)
Biogenic in origin
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Structure II Gas HydrateCrystal-Diamond Lattice
May contain largermolecules (5.9-6.9angstroms) such aspropane(C3H8) orisobutane(C4H10)
Thermogenic in origin
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A Little Chemistry
EnvironmentalConcerns
Formation of hydratesfrom gas vent flumes Contribution to
greenhouse effect?
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Hydrates Support DenseBiological Communities Bacterial mats
Tube worms
Mussels
Shrimp
Crabs
Fish
Eels Isopods
Polychaetes (the newly discovered Ice Worm)
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Sediment Failure
http://www.earthinstitute.columbia.edu/news/aboutStory/pdf/28-407.pdf
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Eruptions
Hydrate Ridge
Storegga Slides
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LOCATION OF GAS HYDRATES
Using seismic-reflection
Seismic-reflection Profile
Side Scan Sonar
Coring
http://www.ngdc.noaa.gov/mgg/bathymetry/relief.html
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using seismic-reflection profiles
Bottom Simulating Reflection (BSRs)
http://woodshole.er.usgs.gov/project-pages/hydrates/hydrate.htm
http://woodshole.er.usgs.gov/project-pages/hydrates/hydrate.htmhttp://woodshole.er.usgs.gov/project-pages/hydrates/hydrate.htmhttp://woodshole.er.usgs.gov/project-pages/hydrates/hydrate.htmhttp://woodshole.er.usgs.gov/project-pages/hydrates/hydrate.htm7/30/2019 Gas Hydrates1
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Side-Scan Sonar
http://gulftour.tamu.edu/cruise_background2.html
http://gulftour.tamu.edu/cruise_background2.htmlhttp://gulftour.tamu.edu/cruise_background2.html7/30/2019 Gas Hydrates1
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Coring
http://www.hydrate.org/about/geology.cfm#Where%20Found
http://www.hydrate.org/about/geology.cfmhttp://www.hydrate.org/about/geology.cfm7/30/2019 Gas Hydrates1
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The Future
USA has suggested in 2000 that $47.5 million beused to explore the option of gas hydrates overa five year period.
Japan has enormous offshore deposits andplans to have production on line by 2015 ($60million on research)
India is also looking into converting its offshore
deposits ($50 million on research) Germany, France, and Australia also starting to
fund research
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Challenges of Hydrate
Utilization as a Fuel Source
Hydrates decompose releasing hydrocarbons as a gaswhen removed from low temp/high pressureenvironment
High costs of long pipelines across unstable continentalslopes
Pipelines in deep cold water become plugged withhydrates during transport
Damage to sensitive chemosynthetic communities
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Potential New Approaches
to Transport Hydrates
Pelletize the hydrate
Inflate large bladder-like blimps with hydrate andtow to shallower water to allow a slow controlleddecomposition
Additives to stabilize hydrates at lower pressuresand higher temperature environments for safertransport by ships
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Advantages of Hydrates as a
Fuel Denser source of hydrocarbons than conventional sources
Amount of conventional fossil fuels will decline in next century
Redirect/dispose of greenhouse methane away from theatmosphere
Cleaner fuel source than oil, coal, and oil shale
Abundant supplies in deep sea and permafrost
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