Shale Gas - Environment Notes

Shale gas is a kind of natural gas that is trapped inside shale strata. It is confined inside low-permeability shale formations, which are fine-grained sedimentary rock that serves as both a source and a reservoir. They are deeper than normal crude oil, which is discovered at 1,500 metres. Extraction of shale oil and gas necessitates deep vertical drilling followed by horizontal drilling. Indian geologists have found three shale gas basins: the Cambay Basin in Gujarat, the Assam-Arakan basin in northeast India, and the Gondwana Basin. This article explains about Shale Gas which is important for UPSC IAS exam preparation.

Shale Gas - Definition

• Shale gas is natural gas that is trapped inside shale layers.
• Shale gas is one of several unconventional natural gas sources, including coalbed methane, tight sandstones, and methane hydrates.
• It is a type of unconventional oil created via pyrolysis, hydrogenation, or thermal breakdown of oil shale rock fragments.
• These processes transform the organic materials contained inside the rock into synthetic oil and gas. Indian geologists have found three shale gas basins: the Cambay Basin in Gujarat, the Assam-Arakan basin in northeast India, and the Gondwana Basin.
• According to the US Energy Information Administration, shale gas will contribute more than 45% of US natural gas production by 2035. China is thought to hold the world's greatest shale gas reserves.
• Most shales are not viable sources of natural gas because they have inadequate permeability to enable considerable fluid flow to a wellbore.
• The primary distinction between shale oil and conventional crude is that the former, sometimes known as 'tight oil,' is discovered in smaller quantities and at greater depths than conventional crude deposits.
• Its extraction necessitates the formation of fissures in oil and gas-rich shale in order to liberate hydrocarbons via a technique known as hydraulic fracturing.

Production of Shale Gas

• Shale gas is extracted via a technique known as hydraulic fracturing, sometimes known as fracking.
• Shale gas deposits are often dispersed horizontally rather than vertically.
• Deep holes or vertical wells are dug down into the desired shale rock formations first, followed by horizontal drilling, which allows for better access to the gas trapped deep within the shale rock formations.
• Following that, high-pressure fracking fluids are injected into the drilled holes. Fracking fluids are composed of water, sand, and chemicals.
• This fracturing liquid opens up fissures in the rocks, allowing trapped gas to flow through the fractures and into collecting wells.

Shale gas exploration in India

• In India, there is currently no large-scale commercial production of shale oil and gas.
• Limited success: The state-owned ONGC began exploring in 2013 and has evaluated shale oil and gas potential in 25 nomination blocks by the end of FY21, but has cut spending in recent years due to little success in shale exploration operations.
• Basins: While ONGC's assessment discovered shale oil prospects in Gujarat's Cambay basin and Andhra Pradesh's Krishna Godavari basin, the company concluded that the quantity of oil flow observed in these basins did not indicate "commerciality," and that the general characteristics of Indian shales differ significantly from those of North American shales.

• Government of India Policy Guidelines: ONGC has selected 50 nomination PML (Petroleum Mining Lease) blocks under Phase-I of the policy guidelines announced by the Government of India (GoI) for the exploration and development of shale gas and oil in India by National Oil Companies (NOCs).
• So far, exploration operations have resulted in the finding of 65 small-to-medium-sized hydrocarbon fields with around 356 million tonnes (oil and oil equivalent gas) of initial on-land reserves.
• The present oil and gas production rates are 750-800 tonnes per day and 2.5-3 million cubic metres of gas, respectively.
• Legal Status of Shale Gas in India: The subject of Hydrocarbons falls under the legislative domain of the central government.
• Hydrocarbon Exploration and Licensing Policy (HELP) was implemented by the central government, which allowed exploration of all kinds of hydrocarbons in the block.
• The Ministry of Petroleum and Natural Gas released a “Draft Policy for the Exploration of Shale Oil and Gas in India” in 2012.

Shale Gas - Challenges

• Massive water demand for fracking
• Contamination of groundwater is a possibility.
• Another obstacle of the fracking process is the recycling and leakage difficulties related with the flowback water, which is frequently methane-contaminated.
• Excessive methane emissions
• Inadequate handling of drill cuttings
• Inadequate waste water disposal procedures
• In comparison to traditional sources, shale oil often creates more pollution during extraction, albeit the extent depends on whether or not the operators prevent wasteful and needless emissions.

Wayforward

• The optimal technique of water management should be recycling and reusing fracking water.
• Enforcing clear and realistic legislation on environmental and water concerns.
• India's soil contains 293 billion tonnes of coal. Environmental concerns make extraction difficult.
• However, 'underground coal gasification' can generate 6,900 trillion cubic feet of gas, which is far more than shale reserves.
• India's shale resources are estimated to be 65 trillion cubic feet. The potential for CBM in India is estimated to be 450 tcf.
• As a result, the emphasis must be on CBM exploration rather than the hazardous shale industry.
• Coal bed methane (CBM), which is produced from coal beds, is also an unconventional gas that occurs significantly closer to the land surface than shale gas.

Conclusion

Shale gas is natural gas trapped inside shale strata. Among the unconventional natural gas sources are coalbed methane, tight sandstones, and methane hydrates. It is a form of unconventional oil that is produced by the pyrolysis, hydrogenation, or thermal breakdown of oil shale rock pieces. Hydraulic fracturing, sometimes known as fracking, is a technology used to recover shale gas. There is presently no large-scale commercial production of shale oil and gas in India.

FAQs

MCQs

Question: Consider the following statements about Hydrocarbon Exploration and Licensing Policy (HELP)

1. HELP establishes a unified licensing system for all hydrocarbons, including oil, gas, and coal bed methane.
2. Oil corporations can choose their own blocks under the HELP Open Area Licensing (OAL) policy.

Which of the above statements is/are correct ?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

Question: Which of the following statements is/are correct about Coal Bed Methane?

1. Shale gas is discovered between 2,500 and 5,000 metres under the earth's surface.
2. The most popular method of extracting shale gas is 'hydraulic fracturing'.
3. Shale gas is trapped behind the hard rocks.

Select the correct answer using the code given below:

(a) 1 and 2 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1, 2 and 3