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Theoretical model of hydrate formation in natural environments Zatsepina, Olga
Abstract
The solubility of two hydrate-forming gases, C02 and CH4 , is calculated over a range of pressure and temperature. The solubility of gas is shown to be significantly altered by the presence or absence of hydrate. In particular, gas solubility changes abruptly in hydrate presence, allowing it to crytallize from the aqueous solution without the need of any free gas. To test this prediction a set of experiments was performed. In the experiments, an aqueous solution of CO2 was cooled at a pressure of 2 MPa. A variety of methods were examined to detect the growth of hydrate. With cooling and hydrate formation, the physical characteristics of the porous medium (temperature, porosity, gas concentration) change. On the basis of known governing equations and conductivity of an aqueous solution in porous medium, the conductivity change due to hydrate formation was predicted. Conductivity was found to be particularly sensitive to hydrate formation, so electrical potential measurements were used to monitor hydrate growth. These electrical measurements indicated a pronounced resistance increase due to a change of gas concentration in the solution, corresponding to the amount of hydrate produced. Hydrate growth in the system was also detected in temperature data, which indicated a release of latent heat. The calculated phase diagram at typical pressure and temperature conditions in marine environments is applied to establish the gas concentration needed to stabilize hydrate. This information is used in simple methods of hydrate formation to estimate the vertical distribution of hydrate in marine sediments and the rate of accumulation.
Item Metadata
| Title |
Theoretical model of hydrate formation in natural environments
|
| Creator | |
| Publisher |
University of British Columbia
|
| Date Issued |
1997
|
| Description |
The solubility of two hydrate-forming gases, C02 and CH4 , is calculated over a range of
pressure and temperature. The solubility of gas is shown to be significantly altered by the
presence or absence of hydrate. In particular, gas solubility changes abruptly in hydrate
presence, allowing it to crytallize from the aqueous solution without the need of any free
gas. To test this prediction a set of experiments was performed. In the experiments, an
aqueous solution of CO2 was cooled at a pressure of 2 MPa. A variety of methods were
examined to detect the growth of hydrate.
With cooling and hydrate formation, the physical characteristics of the porous medium
(temperature, porosity, gas concentration) change. On the basis of known governing
equations and conductivity of an aqueous solution in porous medium, the conductivity
change due to hydrate formation was predicted. Conductivity was found to be particularly
sensitive to hydrate formation, so electrical potential measurements were used to
monitor hydrate growth. These electrical measurements indicated a pronounced resistance
increase due to a change of gas concentration in the solution, corresponding to
the amount of hydrate produced. Hydrate growth in the system was also detected in
temperature data, which indicated a release of latent heat.
The calculated phase diagram at typical pressure and temperature conditions in marine
environments is applied to establish the gas concentration needed to stabilize hydrate.
This information is used in simple methods of hydrate formation to estimate the vertical
distribution of hydrate in marine sediments and the rate of accumulation.
|
| Extent |
5287647 bytes
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| Genre | |
| Type | |
| File Format |
application/pdf
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| Language |
eng
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| Date Available |
2009-03-09
|
| Provider |
Vancouver : University of British Columbia Library
|
| Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
|
| DOI |
10.14288/1.0053015
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| URI | |
| Degree | |
| Program | |
| Affiliation | |
| Degree Grantor |
University of British Columbia
|
| Graduation Date |
1997-05
|
| Campus | |
| Scholarly Level |
Graduate
|
| Aggregated Source Repository |
DSpace
|
Item Media
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Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.