Why in news?
Since 27th May 2020, natural gas has been continuously flowing out of a gas well in Assam following a blowout.
Where is the oil rig?
- The Baghjan 5 well is a purely gas-producing well in Tinsukia district.
- It is at an aerial distance of 900 metres from the Dibru-Saikhowa National Park.
- It was drilled by Oil India Limited (OIL) in 2006.
- It is one of the most prolific gas reservoirs owned by OIL.
- It produces around 80,000 standard cubic metres per day (SCMD) of gas from a depth of 3,870 metres.
- The current discharge is at 90,000 SCMD at a pressure of 4,200 PSI, far higher than the normal producing pressure of around 2,700 PSI.
Why do blowouts happen?
- Sometimes, the pressure balance in a well may be disturbed leading to ‘kicks’ or changes in pressure.
- If these are not controlled in time, the ‘kicks’ can turn into a sudden, uncontrolled release of gas/oil or blowout.
- The possible reasons behind blowouts include simple lack of attention, poor workmanship, bad maintenance, old age, sabotage, morpho-tectonic factors, etc.
- A device called a blowout preventer is usually installed in wells.
Why was there a blowout at Baghjan?
- The gas well at Baghjan was being serviced, and a new sand was being tested at another depth in the same well.
- The existing well-head (the exposed top portion) was also being repaired.
- For repairing the well-head, the well was temporarily killed or the producing zone was shut down.
- The blowout preventer was also removed.
- But suddenly, gas started to ooze out of the exposed well.
- Before anyone could do anything, it broke through our cement barrier.
- The inquiry is going on regarding how and why it happened, how the gas came out of the ‘killed zone’.
Why is it so difficult to control?
- The control of a blowout depends on two things:
- The size of the reservoir and
- The pressure at which the gas/oil is flowing out.
- This reservoir was particularly difficult to control since it was a gas well and ran the risk of catching fire at any point.
- While many blowouts automatically collapse on their own, it can take up to months.
- To control a blowout, the first step is to pump in water, so that the gas does not catch fire.
What is being done?
- A crisis management team from OIL and ONGC intend to create a water umbrella to protect workers while they hook up the blowout preventer.
- For that, a temporary reservoir, channel cables or temporary pipelines have to be built from the Dangori river nearby.
- With very limited space and non-availability of open space above the well head, placement of the BOP is a huge challenge and entails a huge risk.
- It is planned to place the BOP on the well head through a hydraulically driven mechanical transporter.
- Drilling mud will have to be pumped in immediately after capping the well by the BOP.
- OIL has reached out to Singapore-based firm Alert Disaster Control.
How serious is the impact to the neighbourhood?
- As many as 1,610 families with 2,500-3,000 people have been evacuated to relief camps.
- There are reports of deaths of a river dolphin, and a variety of fish.
- While the administration has kept an ambulance with paramedical staff on standby, locals have complained of symptoms like headache, etc.
- The gas (a mix of propane, methane, propylene and other gases) is flowing with the wind, towards the northeast.
- That is a radius up to 5 km and condensate is mostly falling on bamboo, tea gardens, banana trees and betel nut trees.
- Since the gas is moving through the air, the condensate is falling into Dibru-Saikhowa National Park too.
- Also close is the Maguri-Motapung wetland —an Important Bird Area notified by the Bombay Natural History Society.
- The park is famous for its birds, butterflies, wild cats, and feral horses.
- The impact is visible in the sense that one can see,
- Traces of condensate on the water bodies,
- The numbers of birds have decreased, not because they have been killed but because they have flown away.
Source: The Indian Express
