Fracking is the technique used for extracting hydrocarbon resources from ‘shale reservoirs’ by drilling deep horizontal wells.
But there is considerable evidence to suggest that this method is detrimental to the environment, and governments need to exercise restraint.
What are shale reservoirs?
Apprehensions that fossil fuels will be depleted by 2050 have been challenged by some experts who’ve argued that there are still vast unexplored reserves.
Among the reserves that count for augmenting energy supplies is ‘shale gas’ and ‘shale oil’ both of which are estimated to be abundant underground.
Hydrocarbons are conventionally found at about 1,500 m depth, but shale gas and oil are usually found at depths of about 2,500-5,000 m.
They are classified as an unconventional hydrocarbon source and their extraction requires deep vertical drilling followed by horizontal drilling.
Pioneers - In the U.S., shale gas has been commercially exploited for two decades, and which has caused their fuel costs to drop considerably.
Shale discovery has also benefitted the US politically, as it effectively destroyed the clout of “Organisation of the Petroleum Exporting Countries” (OPEC).
Similarly, if India commercially exploits shale deposits, it could meet its ever-increasing energy demand, and decrease its fuel import bills.
What is fracking?
Unlike conventional reservoirs, porosity of shale is very less – which therefore gives out little flow output after merely perforating (opening) the well.
Hence, to increase the porosity of the reservoir and facilitate flows, the reservoir rock is fractured by using ‘hydraulic fracturing’ (fracking).
In this method, high volumes of water mixed with certain chemicals are pushed down the well, to break the rocks and release the trapped resource.
Fracking has proved to be an economically viable tool in extracting shale gas.
India’s case - The government introduced a policy on shale gas and oil in 2013, permitting 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.
However, environmental groups have strongly criticised this move, which they say will have adverse environmental impacts.
Notably, countries like Germany and France and subnational governments like Scotland have banned fracking.
What are the environmental risks of fracking?
Fracking consumes large amounts of water (about 1.5 crore lts/well) and is bound to impact irrigation and other local requirements.
Additionally, this water is mixed with as much as 260 chemicals and pumped into the reservoir at high pressure to create cracks in the rocks.
The US experience shows that as many as 260 chemicals were used, of which 83 have been identified to pose a risk to human life and environment.
The disposal of the water used for fracking is another big challenge as such vast quantities has to be reprocessed before draining them out.
Further, about 25-90% of the fluid that is pumped in is lost within the reservoir and is not retrieved back.
This unrecoverable volume hence puts the nearby underground water sources at a high risk of contamination – some cases have already been documented.
Fracking also has other impacts such as increased air emissions (including greenhouse gases) and seismic activity – as recognized by some EU studies.
While some do contest the risks of fracking, the evidence currently seems to be pointing otherwise, which hence calls for a rethink.
