Previous Year Question
In which of the following regions of India are shale gas resources found?
Cambay Basin
Cauvery Basin
Krishna-Godavari Basin
Select the correct answer using the codes given below.
1 and 2
Only 3
2 and 3
1, 2 and 3
Correct Answer: D
Detailed Solution
The Directorate General of Hydrocarbons under the Ministry of Petroleum and Natural Gas has recorded shale-gas potential in several sedimentary basins, including the onland parts of Cambay, Gondwana, Krishna-Godavari and Cauvery. Therefore, all three basins mentioned in the question are correct.
Basin-wise position
Basin | Geographical location | Shale-gas position |
Cambay Basin | Mainly Gujarat | Shale-gas resource and exploration area |
Cauvery Basin | Mainly the Tamil Nadu–Puducherry region and adjoining offshore area | Onland basin with shale-gas potential |
Krishna-Godavari Basin | East coast, mainly Andhra Pradesh and the adjoining offshore area | Shale-gas resource and exploration area |
What is shale gas?
Shale gas is natural gas consisting mainly of methane that remains trapped within very low-permeability shale rocks.
It is an unconventional hydrocarbon. Conventional gas migrates from its source rock and accumulates in a porous reservoir rock, whereas shale gas generally remains within its original shale formation.
Because of the low permeability, its extraction generally requires techniques such as horizontal drilling and hydraulic fracturing.
Significance of the estimates
ONGC estimated approximately 187.5 TCF of shale-gas resources in five basins—Cambay, Ganga Valley, Assam and Assam-Arakan, Krishna-Godavari and Cauvery.
The USGS estimated approximately 6.1 TCF of technically recoverable shale gas specifically in the onland parts of Cambay, Krishna-Godavari and Cauvery.
These figures should not be added together. The first is a broader resource estimate, whereas the second estimates the portion considered technically recoverable.
The expression “resources are found” refers to prospective or assessed geological resources. It does not mean that every basin contains an equal quantity of proved, commercially recoverable reserves or is producing shale gas.