Assam Gas Leak – Burning Issues

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CONTEXT

Since the morning of May 27, natural gas has been continuously flowing out of a gas well in Assam following a blowout —or a sudden, uncontrolled release of gas/oil.
Meanwhile, people from surrounding villages have been evacuated, while a variety of fish and an endangeredGangetic dolphin have died.

The Baghjan5 well is a purely gas-producing well in Tinsukia district.
It is at an aerial distance of 900 metresfrom the Dibru-Saikhowa National Park.
It was drilled byOil India Limited (OIL) in 2006.
It produces around 80,000 standard cubic metresper day (SCMD) of gas from a depth of 3,870 metres.
As per officials, 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.

Like all forms of energy drilling, natural gas drilling starts when a deposit of natural gas is found deep beneath the Earth’s surface.
To find these deposits, energy company use a variety of methods.
They look at the surface geology of an area, the seismic energy (how energy moves from inside the Earth to its surface) and even the magnetic properties of the underground rock formations.
Once a likely depositof natural gas is located, the energy company then drills down to reach it
A natural gas well isn’t at all like a water well (where you drill a hole in the ground and water fills it).
Natural gas tends to be contained within the underground rock itself.
The rock must be broken to release the gas.
And if it’s brought out the wrong way, it can contaminate the groundwater supply surrounding it.
Energy companies send electric charges down the well, which affect the rock around it.
After the charges are set off, a highly-pressurized liquid fracking solutionis sent down the well.
This solution breaks up the rocks, releasing the natural gas.
Since the gas is lighter than the fracking solution, it rises to the top of the well for capture.
Natural gas is a mix of propane, methane, propyleneand other gases

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 blowout.
Lack of attention, poor workmanship, bad maintenance, old age etc.
A device called a blowout preventer is usually installed in wells.

The gas well at Baghjanwas being serviced, and a new sand was being testedat another depth in the same well.
To repair the well-head, you need to temporarily ‘kill the well’ or shut downthe producing zone.
“The blowout preventer was also removed, since we were in the process of repairing the well-head.
But suddenly, gas started to ooze out of the exposed well.
Before anyone could do anything, it broke through our cement barrier,” said TridivHazarika, spokesperson of OIL.

OIL-owned oil well in Dikhom(Dibrugarh) in 2005.
An ONGC-owned oil well in Rudrasagarin the 1970s. Took three months to contain.

The control of a blowout depends on two things: Sizeof the reservoir and the pressureat 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.
To control a blowout, the first step is to pump in water, so that the gas does not catch fire.

As many as 1,610 families with 2,500-3,000 people have been evacuated to relief camps.
Locals have complained of symptoms such as burning of eyes, headache etc.
There are reports of deaths of a river dolphin, and a variety of fish.
While the well is outside the Eco Sensitive Zone of the park,
The boundary does not matter since the gas is moving through the air.
Condensate is falling into Dibru-Saikhowa National Park too.
Also close is the Maguri-Motapungwetland — an Important Bird Area notified by the Bombay Natural History Society.