Shale Gas

Let us begin with a basic definition.

Shale gas is a natural gas, just like the one used in our LPG cylinders or piped cooking gas. The main component of this gas is methane (CH₄)—a clean-burning fuel. Along with methane, there are small quantities of ethane, propane, butane, and trace amounts of gases like carbon dioxide, nitrogen, and hydrogen sulfide.

Now, this shale gas is not floating around freely. It is trapped deep inside the Earth, inside a very special type of rock called shale.

What is Shale?

To understand this, think historically.

Imagine ancient oceans or seas—millions of years ago, at the bottom of these water bodies, a thick layer of mud accumulated, full of organic matter (dead plants, tiny sea organisms, etc.).

Over time, more and more layers piled on top of this mud. Due to the weight of the upper layers and the heat of the Earth, that soft mud gradually compressed and turned into a fine-grained sedimentary rock called shale.

Now, within this shale, the organic matter got converted into natural gas due to heat and pressure—just like cooking something in a pressure cooker over a long period.

Conventional vs. Shale Gas Deposits

Some of this gas escaped and moved into nearby sandstone rocks, which have larger pores and high permeability—think of it like a sponge soaking up water. These are called conventional gas deposits—easier to extract.

But most of the gas remained trapped inside the tight, less permeable shale rock—this is what we call shale gas.

So now, the challenge is:

How do we extract this gas from such a tightly packed, impermeable rock?

Extraction Techniques – Horizontal Drilling & Hydraulic Fracturing

Why special methods are needed?

Shale is like a hard, compact biscuit with no holes—gas can’t flow easily. So normal vertical drilling (used for conventional gas) won’t work well here.

Horizontal Drilling

First, a vertical well is drilled down to the shale layer (usually more than 1,500 meters deep), and then the drill turns horizontally—just like inserting a needle vertically into a layered cake and then turning it sideways to go through the layers.

This allows us to cover more surface area inside the shale rock.

Hydraulic Fracturing (Fracking)

Now comes the critical part.

A mixture of water, chemicals, and sand is injected at very high pressure into the shale layer. This breaks open tiny cracks (fissures) in the rock. This process is called fracking.

• Water provides the pressure to crack the rock.
• Chemicals help reduce friction and assist in the movement of water and gas.
• Sand particles enter these tiny cracks and keep them open—otherwise, the rock would collapse again, blocking gas flow.

Refer to the following video on Extraction of shale gas:

How is shale gas extracted? Fracking – Vaca Muerta

Role of Guar Gum

Here’s an interesting detail.

During fracking, we need the water to carry sand particles deep into the cracks. For that, we use Guar Gum—a thickening agent extracted from guar beans (grown mostly in India).

Guar gum increases the viscosity (thickness) of water, turning it into a gel-like fluid that can carry sand grains more efficiently.

Think of it like this: It’s easier to mix dry fruits into a thick milkshake than plain water—because the thick fluid can hold and transport particles better.

Environmental Concerns

This technique has sparked intense debate—especially from environmentalists. Here’s why:

• Fracking requires large tracts of land—leading to deforestation in some cases.
• There is concern about chemicals used in fracking seeping into groundwater—potentially contaminating drinking water sources.
• The high water usage is also a concern, especially in water-scarce regions.

However, the industry argues that the water used can be treated and reused, reducing the need for fresh water and disposal.

Let’s quickly revise everything:

Topic	Key Points
Shale Gas	Mainly methane, trapped in shale rock
Formation of Shale	From mud rich in organic matter under ancient seas
Conventional vs Shale Gas	Shale gas is trapped in low-permeability rocks, needs special techniques
Extraction Method	Horizontal drilling + Hydraulic fracturing (fracking)
Fracking Components	Water (pressure), Chemicals (aid flow), Sand (holds cracks open)
Guar Gum	Thickens water to better carry sand
Environmental Issues	Deforestation, water contamination, water usage

Global Landscape of Shale Gas Reserves

Let’s first look at the global scenario—who has how much?

Country	Technically Recoverable Shale Gas Reserves (TCF)
USA	1161
China	1115
Argentina	802
Algeria	707
Canada	573
India	100(approx.)
World Total	7795

🧠Interpretation:

• USA is the global leader in production, although in reserves China is not too far.
• Till the year 2000, shale gas production in the US was almost zero, but within two decades, it transformed the global energy map.

Shale Gas Reserves in India

Now shift the lens to India.

⛏️ Which basins have shale gas/oil?

India’s sedimentary basins with shale potential include:

• Cambay Basin (Gujarat)
• Gondwana Basin (Central India)
• Krishna-Godavari (KG) Basin (Andhra Pradesh)
• Cauvery Basin (Tamil Nadu)
• Indo-Gangetic Basin
• Assam-Arakan Basin

📊 ONGC estimates about 187.5 TCF in 5 major onland basins:

Cambay, Ganga Valley, Assam & Assam-Arakan, KG Onland, Cauvery Onland

But despite this potential, India’s shale gas production remains very low.

Government Initiatives

In 2013, the Government of India launched a Shale Oil and Gas Exploration Policy, allowing National Oil Companies (like ONGC and OIL) to explore shale reserves.

But policy alone isn’t enough—challenges remain.

Why Is India Struggling? If US can why India can’t?

Challenges	Explanation
Water Scarcity	Fracking needs huge water volumes. India is water-stressed; the US is not.
Legal Constraints	In the US, companies aren’t bound to disclose fracking chemicals. India lacks such regulatory flexibility.
Poor Mapping	The US has mapped all its reserves in detail. India still lacks clear data on recoverable shale.
Policy Gaps	India’s petroleum leases exclude shale. So, legal contracts need reworking.
Lack of Infrastructure	Most shale reserves (especially in eastern India) don’t have a supporting pipeline network for gas transport.