ONGC's Sagar Samrat Struck Oil 160 Kilometres off Mumbai on 19 February 1974, and the Mumbai High Field Has Been Producing Since 1976

On 19 February 1974, at the break of dawn, ONGC’s crew on the drill ship Sagar Samrat opened a test on well H-1-1 in the Bombay High structure, about 160 kilometres off Mumbai, and oil came up at 500 psi. ONGC’s own account of the day says the oil measured 43.6 degrees on the API scale, a gauge on which a higher number means lighter, more valuable crude. The company calls it the day a new era began for it.

The field, now named Mumbai High, lies in the Arabian Sea off Maharashtra and started production in 1976. On 18 February 2024 ONGC held a golden jubilee event for the discovery, attended by the Union Minister of Petroleum and Natural Gas, the Petroleum Secretary and the company’s chairman, and the ministry called the 50-year record a “national treasure” in its release the next day.

A Japanese-built rig and a dry well first

ONGC traces its start to 1956. According to its history page, the Government of India adopted the Industrial Policy Resolution in April that year, the oil directorate was raised to a commission in August, and experts from the United States, West Germany, Romania and the Soviet Union advised the government. ONGC says it went offshore in the early 1970s and found a giant oil field in the form of Bombay High.

Before the drilling there was seismic survey work. The FundingUniverse company history says a 1963 offshore survey found promising structures under the Gulf of Cambay and that Soviet survey work between 1964 and 1967 identified more, using the ship Akademik Arkhangelsky (the sources spell the name several ways). PTI’s 2024 account credits a Russian and Indian team on that vessel with the find. India’s relations with the Soviet Union during these decades are covered in India and Russia: seven decades of defence, energy and space.

The rig for the job was Sagar Samrat, a self-elevating jack-up drill ship. The Press Information Bureau (PIB) says it was built at the Mitsubishi yard in Japan, commissioned in 1973, and sailed from Hiroshima on 3 April 1973. ONGC’s account says it reached Bombay in May 1973 and drilled a first well at the Tarapur structure, which found nothing but taught the engineers a great deal. The rig was then moved to the Bombay High structure. India’s wider ties with Japan are covered in India and Japan: metro lines, bullet trains and a special strategic and global partnership.

The drilling log of well H-1-1

ONGC’s release gives the sequence in detail. The rig’s four legs went down on 31 January 1974 and hit solid ground, with the hull jacked up 50 feet above the water in a depth of 62 metres. Drilling was spudded, meaning started, on 3 February 1974.

The instruction was to stop at the first sign of a “drilling break”, an unusually fast stretch of drilling that often marks a zone holding oil or gas, because such zones can be only 2 to 5 metres thick. The break came at 962 metres. Cuttings that reached the surface an hour later glowed golden yellow under a fluoroscope, the colour of oil. The crew cut an 18-metre core instead of drilling on, and the core showed streaks of oil.

To be sure, they needed a drill stem test, which isolates a zone and lets its fluids flow up the pipe. ONGC says there was only one set of the tools in its western zone, kept at Ahmedabad. A team was mobilised, was ready by 18 February, and opened the well the next morning. The oil, mixed with a little gas, was burnt off because there was no storage on site.

Production from 1976

ONGC’s own release on its technical partner says Mumbai High was discovered by ONGC in 1974 and started production in 1976. PTI’s 2024 retrospective gives the date as 21 May 1976, and the Offshore Technology and MarineLink profiles also put the start in 1976.

For the peak, published figures differ. PTI and Outlook Business give 476,000 barrels of oil a day in 1989, with 28 billion cubic metres of gas that year. The Offshore Technology and MarineLink profiles give 400,000 barrels a day, reached in 1985 and held until 1989. Output has declined gradually since, and PTI, Outlook Business and MarineLink put it at about 134,000 to 135,000 barrels a day in 2024.

ONGC’s FY26 corporate profile says the company as a whole contributes about 73 per cent of India’s crude oil and about 57 per cent of its natural gas (older ONGC pages say about 75 per cent for crude and gas together). Mumbai High’s own share is quoted differently by different outlets: Outlook Business says almost 38 per cent of India’s production, MarineLink says about 27 per cent of daily oil output. No official statistics page opened for this article states it, so neither figure is given here as settled.

The rig that kept working

Sagar Samrat did not retire after the discovery. PIB says that in 32 years it drilled almost 125 wells and was involved in 14 key offshore oil and gas discoveries. It has since been converted from a drilling rig to a mobile offshore production unit, which began producing on 23 December 2022. It sits at the WO-16 field, 140 to 145 kilometres west of Mumbai, in 76 metres of water, and is designed to handle 20,000 barrels a day of crude oil and export up to 2.36 million cubic metres of gas a day. The Union Minister re-dedicated it on 28 January 2023.

At that event the Minister described the rig as a testimony to India’s vision of producing its own oil at a time when the country was widely labelled barren for hydrocarbons, and noted that India imports about 85 per cent of its petroleum requirements.

Keeping an old field working

A field of this age needs reinvestment. PIB records the Mumbai High South Redevelopment Phase-III project, approved in 2014 at Rs 6,068 crore (a crore is 10 million). As of 13 September 2018 the project was 89.16 per cent complete, with 57 of 70 wells drilled, and it projected extra output of 7.547 million tonnes of oil and 3.864 billion cubic metres of gas through 2029-30. The same release records a Rs 3,190.69 crore project, approved in December 2015, to extend the life of 48 well platforms across Mumbai High, Neelam and Heera. The final results of these projects are not in any source opened for this article.

In February 2019 the government decided that national oil companies could choose field-specific models, including technical service contracts, for mature fields. In November 2021 the Ministry of Petroleum and Natural Gas issued a clarification about ONGC’s Udaipur meeting of 29 to 31 October 2021 in answer to newspaper reports about privatising Mumbai High. The ministry described the meeting as an internal ONGC strategy session whose suggestions included partnerships for major fields.

Where the records differ

Several points are not settled by one source. ONGC’s “Our Growth Story” timeline lists “First Offshore well” under 1970, while PIB and ONGC’s discovery account describe Sagar Samrat’s well in 1974 as ONGC’s first offshore well. The timeline gives no detail on the 1970 entry, and this article uses 1974 for the drilling at Bombay High.

The day of the discovery is given as 19 February 1974 by ONGC; Offshore Technology says only February 1974. PTI’s dispatch of 19 February 2024 says the field was discovered “on this day 50 years back”, while the ministry’s jubilee event was held on 18 February.

PTI and MarineLink also report cumulative production of 527 million barrels of oil, but that figure does not fit the daily rates in the same reports: 476,000 barrels a day for a full year is about 174 million barrels. This article does not use it.

The next stage: bp and Samudra Manthan

In February 2025 ONGC and bp signed a contract under which bp acts as technical services provider for Mumbai High. World Oil reports that ONGC keeps ownership and operational control, and that bp receives a fixed fee for two years and then a fee linked to incremental production. ONGC’s release says the field continues to see production challenges despite earlier measures such as water injection, gas lift and infill drilling. It also says bp indicated that over the ten-year contract crude oil could rise from a baseline of 45.47 million tonnes to 65.41 million tonnes, about 44 per cent, and in gas from 24.94 to 47.22 billion cubic metres, about 89 per cent. The release expects the increase to show from FY26 and in full from FY28. As of 29 October 2026 no published production data show the result.

Another state company reported a new offshore gas flow in October 2026, described in Oil India’s Godavari-1 well in the Krishna-Godavari Basin. On 31 July 2026 the Union Cabinet approved Samudra Manthan, a National Offshore Exploration Scheme with an outlay of Rs 84,084 crore through FY 2030-31. The Prime Minister’s Office says it covers seismic data, deepwater and ultra-deepwater drilling and common production infrastructure, and is expected to add over 600 million tonnes of oil equivalent in reserves.