Visakhapatnam: Amid the ongoing conflict in the Middle East and disruptions to oil supply through the Strait of Hormuz, the underground crude oil storage facility in Visakhapatnam has once again come into focus.
Developed about a decade ago by Indian Strategic Petroleum Reserves Ltd (ISPRL), the facility forms part of India's strategic petroleum reserve (SPR) system. SPR caverns at Visakhapatnam, Mangaluru, and Padur together hold 5.33 million metric tonnes of crude oil, sufficient for roughly 9-10 days of national consumption, including 1.33 MMT at Visakhapatnam.
These underground caverns are secure from attacks and natural disasters, making them ideal for long-term storage. During wars, geopolitical disruptions, or supply shocks, the reserves provide a strategic buffer, allowing the govt time to arrange alternative imports, stabilise fuel supply, and protect the economy.
Operationally, the SPR allows controlled filling during favourable market conditions and strategic withdrawal during emergencies, strengthening national energy security and resilience against disruptions at maritime chokepoints.
The Visakhapatnam site is located at the foot of the Dolphin's Nose, projecting into the Bay of Bengal. The storage facility is divided into two caverns: Cavern A with a capacity of 1.03 MMT, and Cavern B with 0.30 MMT.
A key advantage of underground rock caverns is security. Being deep inside rock, the crude is naturally shielded from cyclones, storm surges, and other surface-level natural calamities. It also provides strong protection against sabotage, including bombings or missile and drone attacks, as the storage volume is enclosed and surrounded by rock. This is especially valuable for strategic reserves intended to remain operational under wartime or crisis conditions.
Safety is another major benefit. Underground caverns reduce hazards associated with leaks and the accumulation of flammable vapours, thanks to controlled ventilation, monitoring, and isolation systems. Compared with surface storage options like pressurised spheres or refrigerated tanks, rock caverns lower the probability of large fires and mitigate the effects of external heat radiation. Large volumes can be stored with minimal land use, which is crucial in coastal industrial zones where land is scarce and expensive. A reduced surface footprint also simplifies security perimeters and limits environmental and social impacts.
Construction typically involves drill-and-blast excavation in competent rock, with systematic support using rock bolts, shotcrete, and reinforced concrete where required. Cavern geometry is designed for long-term stability, guided by extensive geotechnical investigations. Water curtain systems and grouting maintain a hydraulic barrier, preventing outward leakage by ensuring groundwater pressure exceeds internal oil pressure. Instrumentation monitors seepage, deformation, and pressure to ensure safe operation over decades.
Economically, underground caverns often have lower capital and operating costs than equivalent above-ground storage, partly due to savings on surface structures, piping, instrumentation, and land acquisition.
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About Strategic Petroleum Reserve Program
Visakhapatnam site has a total storage capacity of 1.33 million metric tonnes of crude oil in underground rock caverns
It is part of India's strategic petroleum reserve program, built to enhance energy security by storing crude oil for emergencies
Underground storage uses rock cavern technology, considered one of the safest methods for hydrocarbon storage
The caverns help India align with global energy security standards, providing additional reserves beyond commercial storage in refineries
Provide robust protection against sabotage, attacks, and natural disasters
Being deep underground in rock formations, the caverns minimise risks of fire, explosion, or oil spillage compared to above-ground tanks
Provide natural insulation and pressure stability, allowing large volumes of crude oil or LPG to be stored for extended periods
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