WHY DO I LIKE GAS HYDRATES?
Because they are beautiful...
Because they look like diamonds in rock...
Because they make even pure alcohol soft and pleasant...
Because they are the last hope of
humanity as pure energy source in the near future...
Because they are mistic and unknown...
BECAUSE!!!
I study natural gas hydrates since 1984 and I do not know anything in the World science which could be compared to them. Hydrate stability zone is a global phenomenon comparable with atmosphere, hydrosphere and lithosphere, but we have revealed it only 30 years ago. And all this time we make new and new findings. Most loud of them are:
- natural hydrates containt several times more hydrocarbons than all oil and gas fields discovered as well as undiscovered;
- marine hydrate-containing sediments are the source of new unknown living things like "ice worms";
- marine hydrates can be the reason of ships and planes disappearance in the "Bermuda triangle";
- hydrates can cause catastrophic global warming;
- hydrate-containing sediments are real threat for deep sea constructions and communications
write to:
<vyakushev@hotmail.com>
for more information see at this site:
natural hydrates description - Main parameters of gas hydrates and hydrate-containing sediments we know now
important studies - studies needed to be carry on now for further progress
main hydrate web-sities - most important gas hydrate Web-Sites
Russian hydrate researchers - most qualified Russian gas hydrate researchers and groups
http://geocities.datacellar.net:80/ResearchTriangle/Node/1622/NEWS.HTM - Moscow Hydrate Group News
Short History
Gas hydrates have been discovered experimentally in 1811 by Sir Humphry Davy during chlorine bubbling in cold fresh water.
Later (1832) Michael Faraday has established first chemical formula of gas hydrates, where one gas molecule corresponded to 10 molecules of water.
During 19th and first half of 20th centuries it was determined by different experimental researchers in Europe, that hydrates can be formed by all individual natural gases except hydrogen and helium.
In 1934, when first gas pipelines were introduced into operation, the phenomenon of pipeline blockage by hydrates was described in the USA by E.G.Hammerschmidt and from this time hydrate prevention during oil and gas production and treatment is constant headache for many companies.
In the middle of 20th century M. von Shtackelberg has determined by methods of X-ray diffraction the two main crystal structures of gas hydrates: Cubic Structure 1 and Cubic Structure 2 and confirmed that hydrates are non-stoichiometric clathrate compounds of water.
In 1959 J.H. van der Waals and J.C.Platteeuw have published first fundamental thermodynamic description of gas hydrate phase.
In 1952 A.H.Delsemme and P.Swings first assumed gas hydrate spreading in the cosmic space.
This assumption has been developed later by S.L Miller (1961, 1984), who has also declared (1969) air hydrates formation in the Earth ice sheets (for example, in Antarctica).
In 1948 I.N.Strizhov has published assumption about gas hydrates spreading in permafrost areas. This assumption has been developed later by Yu.F.Makogon (1966), G.D.Ginsburg (1969) and V.P.Tsarev (1970).
In 1970 a group of Soviet researchers initiated by Yu.Makogon has registered officially the discovery of the possibility of gas hydrates existence in the Earth crust at certain conditions.
In 1972 natural gas hydrates for the first time have been recovered in Black Sea (A.Yefremova and B.Zhizhchenko). From this time marine hydrate-containing sediments covering huge areas of sea floor have been revealed by geophysical survey and deep-sea drilling and coring in more than 50 regions of the World ocean and even in large lakes (for instance, Baykal). The number of the hydrate fields discovered increases every year resulted from new research cruises. Total gas amount encapsulated within natural hydrates is estimated now as 21 quadrillion of cubic meter (K.Kvenvolden, 1998).
In 1987 J.Ripmeester et al. reported experimental data on new hydrate molecular structure (Hexagonal Structure H) which theoretically can exist in nature.
In 1988 V.Yakushev publishes experimental data on gas hydrate self-preservation phenomenon, when hydrates do not decompose entirely at temperatures below 273K after pressure drop. This phenomenon strongly extends thermodynamic field of hydrate existence in nature.
In 1998 joint study group of Geological Survey of Canada, Japan National Oil Corp., Japan Petroleum Exploration Corp. and US Geological Survey has conducted a detail study of underpermafrost hydrates in Mackenzie Delta area (North-West Territories of Canada) and established high specific area reserves of natural gas in this field (more than 4 billion cubic meter per 1 square kilometer).
First International Gas Hydrate Conference has been held in USA in 1993, Second - in France, 1996. Third - in USA in 1999, Fourth - in Japan in 2002, Fifth is to be held in Norway in 2005.
In 1995 National Japanese Gas Hydrate program launched, in 1996 National Indian Gas Hydrate program launched, in 1998 National USA Gas Hydrate program launched
Physical and Chemical Properties of Methane Hydrate and Hydrate-Containing Sediments.
Methane hydrate is the most spread (more than 99% of all natural hydrates) in the Earth crust, so when we speak about natural hydrates we mean methane hydrates.
Appearance
Looks like white snow in dispersed state or like grayish ice in monolithic state. Addition of hydrogen sulfide makes hydrates yellow.
Equilibria.
Methane hydrate forms at certain pressure and temperature. For the system liquid fresh water-pure gas at 273K hydrate forms at pressure 2.6 MPa and higher. In the temperature range 260-273K (ice) equilibrium (P/T) hydrate formation curve for methane can be represented by following formula (V.Istomin and V.Yakushev, 1992):
ln P = 8.968 - 2196.62/T, where
P - pressure (MPa ), T- temperature (K).
For the temperature range 273-285 K following formula can be applied (the same source):
ln P = 29.112 - 7694.3/T.
It is necessary to mention, that hydrate formation conditions do not correspond to hydrate dissociation conditions due to kinetic effect of supercooling needed for hydrate crystal growth initiation. Usually this supercooling does not exceed 1.5-2 K. Addition of salts into water elevates formation pressure, addition of hydrocarbon gases, carbon dioxide and hydrogen sulfide to methane decreases formation pressure.
Structure, composition and some properties
Methane hydrates have Cubic structure 1 (CS-1), where gas molecules occupy large and small cavities created by water lattice. Gas molecules are connected with water molecules by hydrogen ( van der Waals) bonds. Water lattice is arranged into pentagonal dodecahedrons (small cavities, D) and tetrakaidecahedrons (large cavities, T). The elementary cell geometric factor of CS-1 is 1.2 nm. Ideal chemical formula for elementary cell is 2D*6T*46H2O or after reduction CH4*5.75H2O
5.75 is the hydrate number. This parameter can change depending on formation conditions and in nature it is approximately 6.0 due to incomplete filling of water cavities by gas molecules.
Main properties of methane hydrate we know:
hydrate density - 917 kg/m3
empty water lattice density - 796 kg/m3
Specific gas content - 164 m3 per 1 m3 of hydrate.
Young modulus - 8400 MPa
Poisson ratio - 0.3
Acoustic wave (Vp) velosity - 3.5-3.8 km/sec
Static dielectric constant - 58
High frequency dielectic constant - 3.4
Heat conductivity - 0.5 W/(m*K)
Heat capacity - 258 J/(mol*K) ; at 270K and hydrate number 6.0.
Heat of phase transition (enthalpy of dissociation): to gas and ice - 18.2 kJ/mol at 273K.; to gas and water - 54,2 kJ/mol at 273K
Spreading and properties of hydrate-containing sediments
Formation of Methane hydrates takes place in the Earth crust when there are favorable thermodynamic conditions ( area including 95% of ocean floor square from water depth 300-600 m and approximately 50% of permafrost square from permafrost thickness 280 m) and favorable lithologic and geochemical conditions. This zone was named as Hydrate Stability Zone (HSZ). Moreover hydrates can be encountered within permafrost outside current HSZ as a relict of ancient hydrate formation due to self-preservation phenomenon.
Hydrate-containing sediments description and properties:
More than 90% of worldwide hydrates are represented by marine hydrates formed by microbial methane. In the same time, thermogenic hydrates are usually much more concentrated than microbial. Marine hydrates are spread within unconsolidated floor sediments of silt or clay type (sometimes sand) with high porosity (35-60% of sediment volume). Hydrate content of these sediments usually do not exceed 15% of pore space. But, according to our limited knowledge, sometimes hydrates can form practically monolithic bodies with thickness of 3-4 meters. These bodies contain enormous volumes of gas. Places of methane hydrate concentration at sea floor produce new forms of marine biota: from new forms of microfauna and microflora up to such big forms as mollusks and "ice worms". Methane is the main source of their food.
This is no secret, that main interest to natural gas hydrates is connected with the possibility of natural gas production from this huge source, but our current knowledge about it is very poor. We know that marine hydrate-containing sediments have following parameters:
porosity - 35-60%
hydrate content - 3-15% of pore space (for microbial hydrates)
permeability - no data
Geophysical and geochemical indications are relative, such as slightly elevated sonic velocities or reduced salinity. Only one seismic record, Bottom-Simulating Reflector (BSR), usually indicates hydrate-containing sediments presence below sea floor. But even this indicator can not be final evidence of hydrate existence, because it can indicate free-gas zone below HSZ. We do not have direct method of hydrate detection except on board study of recovered drill cores. But, due to low hydrate content and their instability at atmospheric pressure, we often lose hydrates in cores before start of these cores investigation.
First main task in natural gas hydrate study now is development of reliable exploration method for hydrate containing sediments. Current remote geophysical surveys such as seismo-profiling give some positive results in hydrate indication (BSR), but there is no information about hydrate content of sediments. Well log methods such as acoustic log and electric log also give indirect data. So, development of new methods and improvement of standard exploration methods are needed.
According to my preliminary study, success could be achieved in development of Nuclear Magnetic Resonance in Artificial Magnetic Field well log tool and acoustic resonance registration of hydrate molecules. These methods have good theoretical base for accurate hydrate content determination within borehole zone.
For remote detection of hydrate-containing sediments further development of seismic survey is needed for marine hydrates and combination of seismic and electric resistivity profiling for underpermafrost hydrates on land.
ALL THE FUTURE PROGRESS IN GAS HYDRATE EXPLORATION CAN BE ACHIEVED ONLY ON EXPERIMENTAL BASE
Second main task is gas production methods development. Current conventional marine gas production, treatment and transport system including large and expensive marine platforms and submarine pipelines is commercially inapplicable for marine hydrate deposits development due to low specific gas content of hydrate-containing sediments. In the same time, gas resources in hydrate fields are enormous and permeability of hydrate containing sediments is assumed enough for gas and water migration under pressure gradient.
These circumstances determine following requirements for possible gas production and treatment system:
1.Gas production must be cyclic to allow gas to migrate to the bottom hole zone.
2. Hydrate formation inside production column must be avoided.
3.Production platform must be unmanned, small and easily movable to produce gas from large area.
4.Produced gas should be transported without preliminary treatment and dehydration to avoid construction of a large expensive platform.
5. Submarine pipeline transport is impossible due to high capital and operational costs.
Principally, all these requirements are executable, although entirely new system of upstream natural gas industry business must be composed, but the main problem is scientific: How to provide gas migration from hydrate and underhydrate sediments to the bottom hole zone?. And here experimental simulation is extremely needed. So:
ALL THE FUTURE PROGRESS IN GAS HYDRATE PRODUCTION CAN BE ACHIEVED ONLY ON EXPERIMENTAL BASE
Experimental study of hydrate-containing sediments is technically complex problem due to hydrate instability at standard conditions. Now there are a few experimental chambers in the world for hydrate-containing sediments study: Moscow State University (Russia), Woods Hole Oceanographic Center (USA) and Geological Survey of Canada. Study possibilities of all of them are limited by their design. Multi-purpose experimental chamber with changing inner equipment would be most optimum for hydrate-containing sediments study and this is most essencial need by now.
http://www.hydrate.org
http://www.acs.org/memgen/rxntimes/rxt1097/rt10gas.htm
http://www.aist.go.jp/GSJ/dMG/hydrate/Intro.html
http://www.telusplanet.net/public/jcarroll/HYDR.HTM
http://walrus.wr.usgs.gov/docs/hydrate.html
http://patzek.berkeley.edu/E11/hydrocarbonsources.htm
http://www.fe.doe.gov/remarks/hydrate_052198.html
http://kristall.uni-mki.gwdg.de/homep4.htm
http://geocities.datacellar.net/CapeCanaveral/Hangar/6280/
http://www.geol.msu.ru/deps/cryology/scie.htm
There are 4 main gas hydrate research groups in Russia. Each group has its specific history and scientific direction.
1. Institute of Inorganic Chemistry of the Siberian Branch of Russian Academy of Sciences (IICh SB RAS, Novosibirsk). This group leading by Prof.Yuri Dyadin - DIED 28 January, 2002 and Dr.Vladimir Belosludov<bel@casper.che.nsk.su> is the oldest Russian gas hydrate group still in action in Russia. Their fields of interest are: molecular dynamics of clathrate compounds, phase equilibria, hydrates at high (up to 4000 MPa) pressures, hydrate structures and fundamental properties of clathrate hydrates.
2. All-Russian Institute of the World Ocean Geology and Mineral Resources (VNIIOkeanGeologia, Sankt-Peterburg). This group leaded by Dr.Gabriel Ginsburg - DIED 5 May, 1999 and Dr.Valeri Soloviev- DIED 19 September, 2005 now is headless... Griefly... A part of gas hydrate activity is continuing by Dr. Leonid Mazurenko <leonidius@yandex.ru
> That was the most well-known Russian research group on marine gas hydrates. Their fields of interest were: origin and geology of marine hydrates, properties of hydrate-containing sediments, geophysic and geochemical exploration, resource assessment. They have conducted special study on Messoyakha gas field in West Siberia which is supposed to be hydrate-containing.
3. Institute of the Earth Cryosphere of the Siberian Brunch of Russian Academy of Sciences (IEC SB RAS, Tyumen). This group leading by Dr.Anatoly Nesterov<nesterov@ikz.ru> is the most advanced in kinetic studies of gas hydrates with surfactants and mineral adds. Their fields of interest are: phase equilibria of gas hydrates with different solutions, hydrates within permafrost, hydrate kinetics.
4. Moscow Gas Hydrate Group from Research Institute of Natural Gases and Gas Technologies (VNIIGAZ, Moscow) and Moscow State University (MSU, Moscow). This group leading by Dr.Vladimir Istomin<istomin@gol.ru>, Dr.Vladimir Yakushev< vyakushev@hotmail.com> (both-VNIIGAZ) and Dr.Evgeny Chuvilin<chuvilin@geol.msu.ru> (MSU) conducts a wide range of gas hydrate studies - from fundamental properties to field drill samples recovery and study. Practically all aspects of gas hydrate study are involved into their field of interest, but main studies are carrying on thermodynamic equilibria, experimental equipment design and manufacturing, hydrate-containing sediments experimental study and industrial applications of gas hydrates.
Archive (historical news, reviews, proceedings) of this site is avaliable at
http://geocities.datacellar.net:80/ResearchTriangle/Node/1622/archive.html
this page was created February 4, 1999