Gas Hydrates1

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.htm


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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.html


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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.cfm


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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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Gas Hydrates1