The Shale Gas

Shale gas and oil are unconventional natural resources. They are found at 2,500-5,000 metres below the earth’s surface. They are deeper in comparison to conventional crude oil found at 1,500 metres. The process of extracting shale oil and gas requires deep vertical drilling followed by horizontal drilling.

The most common way to extract shale gas is ‘hydraulic fracturing’ (fracking), Shale gas is trapped under low permeable rocks.

Hydraulic Fracturing: Most Common way to extract Shale Gas:

Hydraulic well fracturing (“fracking”) is the process of pumping fluid into a wellbore to create enough pressure to crack or fracture the rock layer. Fractures are created by pumping large quantities of fluids at high pressure down a wellbore and into the target rock formation. The fluid usually contains a “proppant,” like sand, that helps keep the fractures open to allow oil and gas to be produced to the well.

The process requires around 5 to 9 million litres of water per extraction activity, posing a daunting challenge to India’s fresh water resources. Shale oil is an unconventional oil produced from oil shale rock fragments by pyrolysis, hydrogenation, or thermal dissolution. These processes produce synthetic oil and gas which can be used as a fuel or upgraded refinery feedstock

  • Shale oil also refers to crude oil produced from shales of very low permeability formations, called as “tight oil”.
  • Shale oil is formed by accumulation of mud, silt and organic wastes and, heat & pressure being applied on these biological wastes for millions of years.
  • Shale is a fine sedimentary rock that contains high amount of organic matter which can produce a hydrocarbon. But the shale does not have permeability required to extract oil from it. So, processes are required to create fracturing on these rocks to get the gas to the surface.

Shale rock

Shale oil extraction methods:

  1. Mined shale oilsare transported to the processing plants, heated to 500OC, and oil comes out from these rocks.
  2. Situ technique:Oil shale is broken by explosion and Kerogen comes out like crude oil from these rocks.

Negative Consequences by using the Shale Gas:

  • It requires large amounts of water, on an average, it requires 15,000 m3/well.
  • It also requires relatively larger surface area.
  • It is bound to impact irrigation and other local requirements.
  • In the US, experience out of 260 chemical substances shows that, 58 have been identified to pose a risk to human life and environment, out of them eight are carcinogens and 17 are toxic to freshwater organisms.
  • Fracking can cause tremors on the deeper areas of earth

  • 25-90% of the fluid is not retrieved and cracks in the shaft are possible, hence there will be a risk of pollution to nearby underground water.
  • The instances of underground pollution are reported in US and Canada.
  • Fracking has other impacts such as increase in air emissions, including greenhouse gases and seismic activity.

The Government introduced a policy on shale gas and oil in 2013. It permitted National Oil Companies to engage in fracking.

  • Under the first phase, shale gas blocks were identified in Andhra Pradesh, Arunachal Pradesh, Assam, Gujarat, Rajasthan and Tamil Nadu.

Even the well-developed western countries like Germany and France and sub-national Governments like Scotland have banned fracking.

Indian households and irrigation thrive on groundwater. Implementation of the fracking processes without a consultative thought through process, especially on ‘water usage policy’, may result in larger issues including water stress, contamination of groundwater, and related health hazards.

But as the process stands today, we are missing an opportunity to comprehensively regulate the fracking process for a sustainable shale gas exploration in India.

As a first step, a sector-specific EIA manual on exploration and production of unconventional hydrocarbon resources may be a good idea.

Table showing EIA Report, 2013 about estimated recoverable Shale Gas resources:

Country Trillion Cubic Feet
China 1,115
Argentina 802
Algeria 707
USA 665
Canada 573
Mexico 545
Australia 437
South Africa 390
Russia 285
Brazil 245
India 95