Natural Gas Methane Hydrates
From ESER oil and gas
Contents |
What are natural gas hydrates?
- At suitably high pressures and low temperatures, natural gas forms a hydrate with water.
- Vast reserves of these hydrates have been identified in cold, deepwater environments.
- Methane hydrate reserves in the range of 300 trillion cubic feed are commonly found.
Where are methane hydrates located?
- Hydrate layers are often found 300m below the seabed -- trapped between an impervious layer and a layer of water
What are the characteristics of hydrates?
- Hydrates are metastable compounds that are stable at high pressures and low temperatures.
- The boundary between free gas and hydrates ranges over a wide range of pressures and temperatures.
- This range of pressures and temperatures is called the methane hydrate equilibrium.
How are methane hydrate reserves developed?
- In order to develop a hydrate reserve, the temperature and the pressure of the reservoir have to be adjusted to a position outside the methane hydrate equilibrium.
- Hydrate reservoir pressure and temperature may be modified in the following ways:
Reduction of hydrate pressure below the hydrate equilibrium pressure
- This technique requires achieving an extremely large reduction in pressure.
- Consequently, this technique of hydrate production is viable in only a handful of reserves where the equilibrium pressure is low.
Increase in the reservoir temperature above the hydrate equilibrium temperature
- This technique is the most practical.
Injection of chemicals to break the hydrate and separate the methane from water
- This technique is used to prevent the formation of methane hydrates in cold and water-wet environments -- most commonly in gas pipelines.
- The extremely high cost of this technique makes it unsuitable for methane hydrate field development.
Where have natural gas hydrate resources been discovered?
- Black Sea
- Blake Ridge
- Bush Hill
- Costa Rica
- Guatemala
- Japan Sea
- Mexico
- Mississippi Canyon
- Nankai
- Peru
- Chile