In which of the following regions of India are shale gas resources found?

1. Cambay Basin

2. Cauvery Basin

3. Krishna-Godavari Basin

Select the correct answer using the code given below:

The correct answer is Option 4: 1, 2 and 3 — Shale gas resources are found in all three of the listed basins: the Cambay Basin, the Cauvery Basin, and the Krishna-Godavari Basin.

To understand why all three are correct, let us first understand what shale gas is and then examine each basin individually.

What is Shale Gas?
Shale gas is a form of natural gas trapped within fine-grained sedimentary rock called shale. It is an unconventional hydrocarbon resource extracted through a process called hydraulic fracturing (fracking). India has been actively exploring its sedimentary basins for shale gas potential, as identified by the Directorate General of Hydrocarbons (DGH) and various government surveys.

Statement 1 — Cambay Basin (Gujarat):
The Cambay Basin, located in the state of Gujarat in western India, is one of India's oldest and most prolific petroleum-producing basins. Studies conducted by the DGH and the U.S. Energy Information Administration (EIA) have confirmed that the Cambay Basin holds significant shale gas potential. The basin contains thick shale formations that trap substantial quantities of natural gas. Therefore, Statement 1 is correct.

Statement 2 — Cauvery Basin (Tamil Nadu / Andhra Pradesh):
The Cauvery Basin is situated along the southeastern coast of India, spanning parts of Tamil Nadu and Andhra Pradesh. This basin is well-known for its conventional oil and gas production, and geological surveys have also identified shale formations with considerable shale gas reserves within it. The DGH's reports on India's unconventional hydrocarbon potential list the Cauvery Basin as one of the promising shale gas regions. Therefore, Statement 2 is correct.

Statement 3 — Krishna-Godavari (KG) Basin (Andhra Pradesh / Telangana):
The Krishna-Godavari Basin is perhaps the most prominent and well-studied basin in India for both conventional and unconventional hydrocarbons. Located along the eastern coast of India (Andhra Pradesh and Telangana), this basin has been at the center of major natural gas discoveries. It is also recognized as one of the most prospective shale gas basins in India. The EIA has specifically highlighted the KG Basin as containing large technically recoverable shale gas resources. Therefore, Statement 3 is correct.

Broader Context — India's Shale Gas Policy:
India notified its Shale Gas and Oil Policy in 2013, permitting national oil companies (like ONGC and Oil India) to explore shale gas in their existing acreages. The DGH identified several sedimentary basins with shale gas potential, including — but not limited to — the Cambay Basin, the Cauvery Basin, the Krishna-Godavari Basin, the Gondwana basins of central India, and the Indo-Gangetic plains. All three basins mentioned in the question are officially recognized shale gas resource zones.

Conclusion:
Since all three statements are individually correct — Cambay Basin ✓, Cauvery Basin ✓, and Krishna-Godavari Basin ✓ — the correct answer is "1, 2 and 3". No basin listed in the question can be excluded, as each one has been confirmed as a shale gas resource area by India's hydrocarbon regulatory and exploration authorities.