Gas Hydrates: ONGC Upbeat to Make a Breakthrough

India's energy security drive may get a shot in the arm with remarkable findings of gas hydrates in the KG basin and in Andaman offshore.

According to the latest report, the prognostic reserves of gas, trapped in hydrates, could be over and above 5 tcm, which is more than the conventional gas reserves.

A senior ONGC official in Dehradoon has also pointed out that the volume of 5 tcm is a very conservative estimate since the study is done in a limited area.

In order to tap this hidden treasure, the National Gas Hydrate Program (NGHP), which is currently coordinating all gas hydrate activities, is in the process of tying up with Indian Institute of Technology, Kharagpur to make a breakthrough in technology development.

"The development of technology for gas hydrates has been a challenge worldwide. In ONGC we are also very much on the job," the official added.

ONGC has been working in the fields of gas hydrates since 1997. Based on reprocessing of seismic data and geological considerations, about 1400 area in KG basin has been delineated as potential gas hydrate bearing zone. The studies of Bottom Simulating Reflector (BSR) on seismic sections have also shown that there could be substantial deposits of gas hydrate in the Andaman offshore. In Andaman, however, the DGH has carried out an extensive survey.

Senior Officials close to the activities in gas hydrate research said the technical committee of NGHP, a Ministry of Petroleum and Natural Gas initiative, has identified 15 locations in KG offshore where coring of gas hydrates will be carried out in phases.

The identification of the locations has been done on the basis of the research, done by ONGC in collaboration with the National Institute of Oceanography, Goa which is also a member of NGHP.

On June 27, the steering committee of the NGHP took a decision that in the first phase five locations will be taken up for drilling/coring in KG basin. Besides these,two locations in the Reliance blocks in East coast, two locations in Andaman offshore and one location in Goa offshore will also be drilled.

The roadmap placed before the NGHP suggests that the first phase coring will be started in December 2004.

Although gas hydrate has been considered as a major succor to the global energy crisis that looms large in the horizon, the people at large know hardly anything about it.

What are gas hydrates?

Hydrates can be formed in systems of water and small molecules. When the small molecules are gaseous at ambient conditions we are speaking of gas hydrates. These small molecules, e.g. methane (CH4), propane (C3H8), carbon dioxide (CO2), nitrogen (N2) but also fluoroform (CHF3) are enclosed in cavities formed by the hydrogen bonded water molecules. The specific conformations of the framework of hydrogen bonded water molecules can exist because of the enclosed molecules in the cavities, i.e., they stabilise the whole structure. Gas hydrates are ice-like inclusion components that are regularly built and can store large amounts of guest molecules. Albeit they look like ice, gas hydrates can exist at temperatures higher than the freezing point of water and elevated pressures, because of the stabilization by the enclosed guest molecules. When these guest molecules are flammable the gas hydrates can be ignited and you get burning ice. The storage capacity for gas of these structures is considerable; i.e., approximately 150 times the storage capacity of compressed gas in case of natural gas. According to a senior ONGC official, one gas hydrate can hold 165 cubic meter of methane gas.

It should be mentioned that in case of the naturally occurring gas hydrate fields there is a concern with respect to the stability of these at changing conditions. It is suggested that when the temperature rises, for example due to the greenhouse effect, the hydrates might become unstable and decompose. A large amount of, mainly, CH4 can be released into the atmosphere, aggravating the greenhouse effect. Because CH4 is even a more severe greenhouse gas than CO2. A sort of runaway greenhouse effect may arise. Lately it was suggested that decomposition of gas hydrate reserves might have played a part in the end of the ice ages on earth.


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