Assam oil rig: ONGC caps leak but residents fear inhaling toxic fumes, fire risk

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09-07-2025

On June 27, the gas leak in a rig in Rudrasagar was finally capped in a joint operation carried out by the Crisis Management Team of the Oil and Natural Gas Corporation of India and Texas-based Crudd Pressure Control where they removed the damaged blowout preventer from the oil wellhead.
Gushes of gas were first observed on June 12, around 11.45 am, during servicing operations at well no RDS-147 A, an oil well in the Rudrasagar oil field, in Sivasagar district in Assam, one of the oldest oil fields of ONGC, the largest state-owned oil and natural gas company of India.
Upon detection, ONGC activated standard safety protocol, and the site was promptly secured. A fortnight later, gas continued to leak at the Rudrasagar oil field. However, following the arrival of a three-member team of oil well control experts from Crudd Pressure Control on the evening of June 20, there was progress in controlling the blowout with flow rate of gas reducing substantially. The team finally brought the gas flow under control on June 27.
'After removing the BOP [blowout preventer], the pre-positioned capping start, prepared at the staging area, was carefully and accurately placed onto the wellhead. This redirected the gas flow securely to the top of the capping stack, ensuring containment and control. The capping stack was firmly installed and secured, following which the BOP was successfully closed, effectively bringing an end to the gas discharge,' the ONGC statement said.
Meanwhile, the Pollution Control Board of Assam issued a show-cause notice to ONGC for operating oil well no. 147A without obtaining mandatory environmental clearance.
ONGC has been granted 15 days to respond to the notice and failing to do so could invite punitive action, including financial penalties and legal proceedings.
The incident has affected at least 1,500 people from 350 families in the vicinity who were relocated to relief camps, reviving the painful memories of the 2020 oil and gas leak at Baghjan oil field in Tinsukia district of Assam, operated by Oil India Ltd.
The leak at Baghjan later escalated into a blowout with a massive fire which raged for more than five months, displacing more than 15,000 residents from 3,500 families.
Assam Chief Minister Himanta Biswa Sarma, after visiting the affected people on June 16, wrote to Union Minister of Petroleum and Natural Gas Hardeep Singh Puri that, unlike previous incidents handled expeditiously, the current approach appears procedural and lacking in visibility. 'I am constrained to convey that the local perception is one of inadequate urgency and seriousness in ONGC's response,' wrote Sarma.
Sarma also announced a compensation of Rs 25,000 from the Chief Minister's Relief Fund for every affected family.
Meanwhile, local people have claimed that SK Petro Services, a private firm deployed by ONGC to supervise the operations at the rig and provide the workforce, was responsible for the accident and demanded the arrest of its owner.
Living near a leaking rig
ONGC discovered oil in Rudrasagar in 1960, making it one of the company's oldest oil fields in India and production began here in 1964. The place is, however, densely populated with several villages in the vicinity like Bhatiapara, Rupohimukh, Bhati Bon Gaon, Radhika Nagar, Boliaghat, Rupohibil Gaon, Dhuliapar etc.
Brojen Das, headmaster of Radhikanagar LP School lives at Rupohimukh village, which is within 500 m of the site of the leak, informed Mongabay India that most people here are from either Matak or Koibarta communities.
Das said that 90% of the people here are farmers and fishers who catch fish at the nearby Dikhow river, a tributary of the Brahmaputra while others are daily wagers, service people and small business owners.
'There are around a hundred families within a 200 m radius of the leaking rig. They couldn't stay at home and went to the relief camps. The schools in the 3 km radius, including my own, have been turned into relief camps and medical camps,' he said.
A statement released by ONGC on June 18 stated that a thorough analysis of the released gas has been carried out through sample collection, confirming that the gas is non-toxic in nature and that the noise levels are also within acceptable limits beyond 500 m.
However, if the gases are non-toxic, why are people and domestic animals getting ill, questioned Das. He said, 'There are mobile medical camps set up by both district administration and ONGC. Not just the gas, but even the loud sound is causing a lot of discomfort. Now serious patients are being taken to Sui-Ka-Pha Municipality Hospital in Demow.'
A doctor currently serving on a mobile medical camp in Rudrasagar on the condition of anonymity as he is not allowed to speak in an official capacity, told Mongabay India that the patients he has treated have mainly complained of irritation in eyes and skin.
'Their vision has become foggy. This irritation in the eyes could be the allergic manifestation of the gas. We have also got patients with diabetes and hypertension though it is not possible to say without investigation if those conditions have spiked because of the gas. Some patients have also complained of palpitation though that can also happen because of the mental stress these people are going through,' he said.
Local social worker Saroj Baruah told Mongabay India that there was a blowout in Rudrasagar in the past as well. 'In 1969, there was a blowout which continued for ten days. Later, a team from Russia was brought in to put out the fire,' said Baruah, who was five-six years old then.
Baruah, who lives in Bhatiapara village, which is 700 m from the rig, said that ONGC took the land from the villagers here on lease after oil was discovered here, and the lease is extended after every 30 years.
Operation to cap the leak
According to the ONGC's media statement, the first step in plugging the leak was to connect the well to a nearby production facility, thereby diverting a portion of the gas in a controlled manner. As an additional safety measure, the team is using the technique of water blanketing.
Speaking to Mongabay India about the challenges in this operation, Subrata Borgohain Gogoi, Professor at the Department of Petroleum Technology and Dean of the Faculty of Earth Sciences and Energy at Dibrugarh University said, 'Now even a little carelessness can lead to a fire. As the gas is in the air, any spark, such as even static electricity from friction between two pieces of cloth can lead to a fire. The presence of Dikhow river nearby was beneficial as its water was used for water blanketing. Now to kill the well, they are pouring junk. The gas is so mobile that it will emerge through the slightest gap.'
'Nobody can predict at what velocity the gas will come out. These kinds of rig accidents occur in the USA, the North Sea and the Gulf of Mexico but they are mainly onshore rigs with almost no population nearby. On the other hand, here the incident has taken place in an offshore rig surrounded by densely populated villages and so many people have been affected,' Gogoi said, adding that there might be negligence on the part of SK Petro. 'They got the bid of operating the rig as the lowest bidder. However, what exactly happened can be said only after investigation,' she said.
Regarding the composition of the gas leaking from the rig no 147A, she said, 'According to the information I received from ONGC, the gas comprises of methane (85-92%), ethane (3.6%), propane (0.5-2%), butane (0.1-1%), carbon dioxide (1-3%), nitrogen (0.5-2%), hydrogen sulphide (less than 0.1%).'
According to reports, ONGC on June 21 asked residents living beyond 500 m from the site of the incident to return home and resume activities like cooking and use of electricity.
Das, meanwhile, said that even if normal activities resume for the local residents, this incident might have a long-term impact on the health of people and environment. 'We don't know how this incident will affect people in the long run, especially children and aged people. Also, it might contaminate the Dikhow river which is a source of livelihood for local fishermen,' he said.