Oil reserves in salt caverns

Subject: Geography

Section: Economic geography

Context:

A Govt-owned engineering firm is studying whether petroleum reserves can be developed in Rajasthan’s salt caverns.

Why do countries need strategic petroleum reserves (SPR) ?

If the idea comes to fruition, India could get its first salt cavern-based oil storage facility. The country’s three existing strategic oil storage facilities — at Mangalore and Padur in Karnataka, and Visakhapatnam in Andhra Pradesh — are made up of excavated rock caverns.
Countries build strategic crude oil reserves to mitigate major supply disruptions in the global supply chain.
India, the world’s third-largest consumer of crude, depends on imports for more than 85% of its requirement — and strategic petroleum reserves (SPR) could help ensure energy security and availability during global supply shocks and other emergencies.

Salt cavern-based reserves vs rock cavern-based reserves

Unlike underground rock caverns, which are developed through excavation, salt caverns are developed by the process of solution mining, which involves pumping water into geological formations with large salt deposits to dissolve the salt.
After the brine (water with dissolved salt) is pumped out of the formation, the space can be used to store crude oil.
The process is simpler, faster, and less cost-intensive than developing excavated rock caverns.
Salt cavern-based oil storage facilities are also naturally well-sealed, and engineered for rapid injection and extraction of oil. This makes them a more attractive option than storing oil in other geological formations.
The salt that lines the inside of these caverns has extremely low oil absorbency, which creates a natural impermeable barrier against liquid and gaseous hydrocarbons, making the caverns apt for storage. Also, unlike rock caverns, salt cavern-based storages can be created and operated almost entirely from the surface.
The entire SPR programme of the United States has so far been based on salt cavern- based storage facilities.
Salt caverns are also used to store liquid fuels and natural gas in various parts of the world. They are also considered suitable for storing compressed air and hydrogen.

Potential in India for storing crude, petroleum products

Rajasthan, which has the bulk of requisite salt formations in India, is seen as the most conducive for developing salt cavern-based strategic storage facilities.

Strategic petroleum reserves programme: story so far

India’s strategic oil reserves are part of the effort to build sufficient emergency stockpiles on the lines of the reserves that the US and its Western allies set up after the first oil crisis of the 1970s. The three existing rock cavern-based facilities were built during the first phase of the programme.
Crude oil from the reserves are to be re- leased by an empowered committee set up by the government, in the event of supply disruptions due to a natural calamity or an unforeseen global event leading to an abnormal increase in prices.
The International Energy Agency (IEA), a Paris-based autonomous intergovernmental organization in which India is an ‘Association’ country, recommends that all countries should hold an emergency oil stockpile sufficient to provide 90 days of import protection.
In India, apart from the SPR that are sufficient to meet 9.5 days of oil requirement, the oil marketing companies (OMCs) have storage facilities for crude oil and petroleum products for 64.5 days — which means there is sufficient storage to meet around 74 days of the country’s petroleum demand.