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Topic: Gas hydrate

	Gas hydrate - Wikipedia, the free encyclopedia
		A gas hydrate is a hydrate consisting of a water lattice in which light hydrocarbon molecules are embedded resembling dirty ice.
		Hydrates normally form when a gas stream is cooled below its hydrate formation temperature in the presence of free water, such as when the gas is colder than its water dew point temperature.
		Furthermore hydrates have a strong tendency to agglomerate and to adhere to the pipe wall and thereby plug the pipeline.
	en.wikipedia.org /wiki/Gas_hydrate (843 words)

	Say "hi" to hydrate
		Gas hydrate is right where it's needed -- off the coast of Europe, the United States and Japan.
		The interest in gas hydrate flared last January when the Japan National Oil Corp. announced that it had found sandstone containing 20 percent gas hydrate off the coast of Japan, which now imports practically all of its energy.
		Even if gas hydrates are as common as the estimates say, nobody knows how to extract hydrates safely, and none is being used today, with the possible exception of one well in Siberia that may be inadvertently producing gas from hydrate.
	whyfiles.org /119nat_gas/2.html (529 words)

	MBARI - Ocean Chemistry of Greenhouse Gases
		Gas hydrates are a solid ice-like phase formed at low temperature and high pressure by van der Waals forces between gas and water molecules, with the "host" water molecules forming a molecular cage which confines the "guest" gas molecules through their mutual electrostatic interaction.
		In the ocean, gas hydrates composed dominantly of methane are common constituents of the shallow marine geosphere (Kvenvolden, 1993), and they occur both in deep sedimentary structures (Dickens et al., 1997), and as outcrops on the ocean floor (MacDonald et al., 1994).
		Gas hydrate formation in the ocean does not involve shaking, and ice crystals are not part of the natural deep sea environment, and therefore laboratory experiments carried out to date have not been able to simulate natural processes.
	www.mbari.org /ghgases/geochem/gas_hydrates.htm (517 words)

	USGS Fact sheet: Gas (Methane) Hydrates -- A New Frontier (Site not responding. Last check: 2007-11-01)
		Methane trapped in marine sediments as a hydrate represents such an immense carbon reservoir that it must be considered a dominant factor in estimating unconventional energy resources; the role of methane as a 'greenhouse' gas also must be carefully assessed.
		Gas hydrate is a crystalline solid consisting of gas molecules, usually methane, each surrounded by a cage of water molecules.
		Methane hydrate is stable in ocean floor sediments at water depths greater than 300 meters, and where it occurs, it is known to cement loose sediments in a surface layer several hundred meters thick.
	marine.usgs.gov /fact-sheets/gas-hydrates/title.html (989 words)

	Gas Hydrate at the USGS, What is it?
		A gas hydrate is a crystalline solid; its building blocks consist of a gas molecule surrounded by a cage of water molecules.
		Hydrate is a gas concentrator; the breakdown of a unit volume of methane hydrate at a pressure of one atmosphere produces about 160 unit volumes of gas.
		Gas hydrate concentration occurs at depocenters, probably because most gas in hydrate is from biogenic methane, and therefore it is concentrated where there is a rapid accumulation of organic detritus (from which bacteria generate methane) and also where there is a rapid accumulation of sediments (which protect detritus from oxidation).
	woodshole.er.usgs.gov /project-pages/hydrates/what.html (430 words)

	Alexander's Gas & Oil Connections - Gas hydrate lies under seabed in Gulf of Mexico
		Gas hydrate, known as "fire in ice," has stood out in recent years as a clean and bountiful energy supply.
		A gas hydrate consists of crystalline blocks each of which are formed by a gas molecule surrounded by a cage of water molecules.
		Taking the exploration and application of gas hydrates as an example, a few approaches have been developed to transform hydrates into gases, but the costs are still too high for industrial use.
	www.gasandoil.com /goc/news/ntn40295.htm (1596 words)

	How to Get Them Out
		In the case of gas hydrate dissociation, this usually involves a combination of releasing the pressure and raising the temperature so that the icy crystals melt or otherwise change form and release the entrapped natural gas molecules.
		This technique is limited only to areas with existing reservoirs of natural gas in its free state, and the extraction of gas from the gas hydrate may be hampered by the formation of ice or the reformation of gas hydrate during the dissociation and extraction process.
		In the case of undersea hydrate reserves, the dissociation and extraction would have to be done without contributing to the instability of the seafloor.
	www.seed.slb.com /en/scictr/watch/gashydrates/how.htm (778 words)

	Gas Hydrates - Natural gas hydrate studies in Canada
		Gas hydrate has been known for many years as a problem in blocking cold-region natural gas pipelines, and as a drilling hazard in the arctic.
		Gas hydrate is a hazard in conventional hydrocarbon exploration, from shallow gas release and from seafloor instability, especially in the arctic and in deep water where hydrate is stable.
		Gas hydrate is a clathrate structure having gas enclosed in water molecule cages.
	cgc.rncan.gc.ca /gashydrates/canada/index_e.php (3514 words)

	Gas Hydrate Theory
		It was the discovery by Soviet workers of a strange “fizzing ice” blocking up their natural gas pipes un 1928- and its identification six years later by the American chemist E G Hammerschmidt as a hydrate of methane — that began the trail leading towards the Bermuda Triangle.
		In case of Methane one litre of the hydrate that had formed in the chilly gas pipes of Kazakhstan in the 1920s amounted to 167 litres of spongy gas and a puddle of water when it made its energetic expansion to normal atmospheric pressure after removal from the icy ground.
		A plume of methane gas would continue to rise once it had reached the ocean surface since methane is lighter than air, and any aircraft flying into this invisible zone of danger would face two hazards.
	members.tripod.com /edward.nygma/triangle/gashydrate.htm (1305 words)

	Icy substance called gas hydrate might be source of clean-burning fuel
		That gas hydrates were first noticed in gas pipelines was no mere happenstance; pressurized lines contaminated with water happen to be a perfect environment for making the icy stuff.
		As natural gas is removed from the reservoir, the pressure within the reservoir would drop, which would cause some of the overlying gas hydrate to dissociate, or melt, releasing more methane into the reservoir which can then be pumped out of the well.
		Holder said it might also be possible to produce methane directly from a gas hydrate deposit by drilling into it; the resulting depressurization would cause dissociation of the hydrates and release methane.
	www.post-gazette.com /healthscience/19991213hydrate1.asp (1666 words)

	TAMU Oceanography: Gas Hydrates
		Gas hydrates are ice-like minerals that form at the low temperatures and high pressures in the deep sea.
		Almost all gas hydrates are found by drilling in sediments at 10s to 100s of meters depth, but the gulf is different.
		Clearly, there is a bright future for gas hydrate research to ensure future supplies of clean-burning energy, to potentially dispose of greenhouse methane, and to understand the role of hydrates as an agent of climate change over geologic time.
	www-ocean.tamu.edu /Quarterdeck/QD5.3/sassen.html (1995 words)

	Gas Hydrate at the USGS, Title Page (Site not responding. Last check: 2007-11-01)
		Gas Hydrate is an ice-like crystalline solid formed from a mixture of water and natural gas, usually methane.
		Gas Hydrate is found in sub-oceanic sediments in the polar regions (shallow water) and in continental slope sediments (deep water), where pressure and temperature conditions combine to make it stable.
		Gas Hydrate can be studied in the laboratory, where a machine is used to create the proper pressure and temperature conditions for hydrate formation, or it can be studied in situ using seismic data collected aboard ships and geophysical models.
	woodshole.er.usgs.gov /project-pages/hydrates (234 words)

	Methane clathrate - Facts, Information, and Encyclopedia Reference article
		Methane hydrates are believed to form by migration of gas from depth along geological faults, followed by precipitation, or crystallization, on contact of the rising gas stream with cold sea water.
		Methane clathrates remain stable at temperatures up to 18 °C. The average methane clathrate hydrate composition is 1 mole of methane for every 5.75 moles of water, though this is dependent on how many methane molecules "fit" into the various cage structures of the water lattice.
		These deposits are located within a mid-depth zone around 300-500m thick in the sediments (the Gas Hydrate Stability Zone, or GHSZ) where they coexist with methane dissolved in the pore-waters.
	www.startsurfing.com /encyclopedia/m/e/t/Methane_clathrate.html (871 words)

	Gas Hydrates at Rice University - About
		Gas hydrates offer a vast, untapped source of energy, a key element in the global carbon balance and past global warming events, and the number one problem for hydrocarbon transmission in deepwater oil and gas production.
		Gas hydrates are crystalline solids composed of gas molecules trapped inside a rigid lattice of water molecules.
		Gas hydrates research may also be a key to gaining greater understanding of carbon cycles and an important element in climate change study.
	www.ruf.rice.edu /~hydrates/about.html (1434 words)

	Gas Hydrates, a Review of an Unconventional Gas Resource – GasChem.com
		In a gas hydrate, the gas molecules are "caged" within a crystal structure composed of water molecules.
		Gas hydrates are also of interest because of their potential role in climate change.
		Gas hydrates in continental shelf sediments can become unstable either as a result of warming bottom water, or as a result of a pressure drop due to a reduction in sea level (such as during an ice age).
	www.gaschem.com /gashydrates.html (2793 words)

	Gas Hydrate Research at the College of Oceanic & Atmospheric Sciences (Site not responding. Last check: 2007-11-01)
		Gas hydrates are created when water and gas combine to form a crystalline substance that looks like ice.
		Gas hydrates are common in marine sediments along the margins of continents, where the methane originates from the decomposition of living things.
		We are engaged in quantifying and calibrating hydrate and free gas volumes using remotely sensed geophysical data, to understand how this relates to the velocity and structure of the sediments.
	quakes.oce.orst.edu /Trehu/GasHydrates (746 words)

	Gas Hydrate Studied in the Northern Gulf of Mexico (Site not responding. Last check: 2007-11-01)
		The generation of gas caused by hydrate dissociation was spectacularly demonstrated when the uppermost several meters of one core blew vertically out the end of the core barrel, flew at least 10 m into the air, and landed in the gulf waters next to the ship.
		The gas hydrate remained on the surface of the water because of its low density and floated away as it dissociated.
		Other gas hydrate, recovered during the cruise, was present either as particles distributed throughout the sediment or as massive chunks that filled the entire 10-cm diameter of the core liner.
	soundwaves.usgs.gov /2002/09 (1118 words)

	COMPOSITION OF WATER AND GAS OF GAS HYDRATE
		The amount of gas hydrate present in marine sediments is one of the more important parameters when the importance of marine gas hydrate is examined as to the environmental impact and resource potential.
		Gas pressure of the chamber steadily increased and reached a stable value in about 10 min.; then the hydrate gas was transferred to a small gas collection chamber for gas analysis.
		Chloride concentrations of five water samples of gas hydrate were between 5 and 62 mM (Table 1); thus, the mole fraction of gas hydrate water in water samples is calculated to be 0.990-0.878.
	www-odp.tamu.edu /publications/164_SR/chap_02/ch2_5.htm (1091 words)

	GAS HYDRATE is an ice
		Gas hydrate often occurs within convergent margins accretionary wedges where there is a high fluid and methane flux generated by the collision between crustal plates.
		Hydrate Ridge forms along a convergent margin from the collision of the Juan de Fuca oceanic crustal plate and the North American plate.
		This potential hydrocarbon resource, the effects on global climate from release of methane trapped in gas hydrates (methane is a greenhouse gas), and the role of hydrates as a catalyst for seafloor slope instability have sparked new efforts to understand the occurrence and distribution of gas hydrates in the shallow seafloor sediments.
	www.ig.utexas.edu /research/projects/gas_hydrate_is_an_ice.htm (608 words)

	Life Support: NURP Unfolds the Mystery of Gas Hydrates (Site not responding. Last check: 2007-11-01)
		She's at the forefront of interdisciplinary research into gas hydrates that is engaging a growing number of scientists with divergent interests and expertise.
		A gas hydrate consists of a gas molecule (green) trapped in a cage of water molecules (red).
		The unfolding of the mystery of gas hydrates and of the world in which they live — and the examination of how they might help us humans meet our energy needs — is also an excellent example of interdisciplinary science at work to mutual and manifest benefit.
	www.oar.noaa.gov /spotlite/archive/spot_gashydrates.html (1070 words)

	Gas Hydrates Research (Site not responding. Last check: 2007-11-01)
		Methane hydrate is by far the most common naturally occurring gas hydrate.
		Methane hydrate is a naturally occurring ice-like crystalline compound in which a crystal lattice of water ice encloses a molecule of methane.
		Methane hydrate is a very dense form of methane; 1 cubic meter of methane hydrate holds the equivalent of 164 cubic meter of methane gas at atmospheric pressure, 25°C. Other gases, including larger hydrocarbons and carbon dioxide, also form hydrate compounds.
	eed.llnl.gov /gas_hydrates/what.html (75 words)

	DOE - Fossil Energy: DOE's Methane Hydrate R&D Program
		A methane hydrate is a cage-like lattice of ice, inside of which are trapped molecules of methane (the chief constituent of natural gas).
		The USGS study estimated the in-place gas resource within the gas hydrate of the United States ranges from 112,000 trillion cubic feet to 676,000 trillion cubic feet, with a mean value of 320,000 trillion cubic feet of gas.
		Natural gas is expected to take on a greater role in power generation, largely because of increasing pressure for clean fuels and the relatively low capital costs of building new natural gas-fired power equipment.
	www.fossil.energy.gov /programs/oilgas/hydrates/index.html (884 words)

	New Page 4
		Methane/gas hydrates, a frozen framework of methane (or other light hydrocarbons) and water, occur beneath thick permafrost in Alaska and other arctic regions, and are seen as BSRs or "bottom - simulating reflections" in seismic reflection data from many offshore areas around the world.
		Gas hydrates may eventually be an important energy resource because of their widespread distribution and because they may provide a fuel that is cleaner burning than ordinary natural gas.
		Gas hydrates are considered to be an experimental resource, and the Department of Energy is actively interested in learning more about such resources in arctic regions as well as in other areas such as the Gulf of Mexico.
	www.geo.arizona.edu /geophysics/rseis/gas-hydrates.html (403 words)

	O.I. Levik Hydrate Site (Site not responding. Last check: 2007-11-01)
		Avlonitis, D.A.: Thermodynamics of Gas Hydrate Equilibria, Heriot-Watt University (Edinburgh), 1992.
		Clarke, M.A.: Determination of the Intrinsic Kinetics of Gas Hydrate Decomposition by Particle-Size Analysis, University of Calgary, 2000.
		Natarajan, V.: Thermodynamics and Nucleation Kinetics of Gas Hydrates, University of Calgary, 1993.
	www.levik.no /hydrates.html (1591 words)

	Mineral Program Activities - Gas Hydrates of Northern Alaska
		Gas Hydrates are crystalline solid consisting of gas molecules, usually methane, each surrounded by a cage of water molecules, with one volume hydrate typically equivalent to 160 volumes methane gas that occur in Arctic regions and in marine sediments of Alaska.
		Industry uses of natural gas in northern Alaska to generate electricity for field operations; in miscible gas floods; gas lift in producing oil wells; reinjection to maintain reservoir pressures, and steam generation for EOR projects.
		Gas Hydrate resources have evolved from a non-producible unconventional gas resource to a research producible energy resource.
	www.blm.gov /ak/ak940/fluids/gashydrates.html (555 words)

	Alexander's Gas & Oil Connections - Scientists explore large gas hydrate field off Oregon coast
		When hydrate forms rapidly, the salts in the surrounding seafloor sediments do not have time to diffuse and the water in the sediment becomes saltier than seawater.
		Although scientists know that gas hydrates are common in the seafloor on the margins of continents around the world, they do not know how much hydrate is present.
		Scientists onboard the research vessel JOIDES Resolution studied the deposits in an area known as Hydrate Ridge to determine how much gas hydrate is present beneath the seafloor.
	www.gasandoil.com /goc/news/ntn24094.htm (484 words)

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