Public Sector Unit Oil India Limited (OIL) has initiated the process of setting up a snubbing unit to “kill the well” at Baghjan oilfield in Assam’s Tinsukia district.
The development came a day after 60 tonnes of snubbing unit, flown in from Canada’s Calgary by the world’s largest cargo aircraft – Antonov An-24, reached the blowout well site late on Wednesday, and 54 days after OIL succeeded in the diversion of gas on September 13 after a failed attempt earlier. The equipment travelled via road from Kolkata, where the flight landed almost two weeks ago.
Talking to this correspondent, OIL spokesperson Tridiv Hazarika said with all equipment and accessories related to snubbing operation in place at the site, arrangement for placing the snubbing unit is in progress. “It is expected that after completion of all necessary pre-operation activities, the well killing operation by the snubbing unit will commence within the next couple of days.”
The Canadian company Alert Damage Control has tied up with Alberta-based Piston Well Services which has moved in its snubbing unit along with four crew members with four other experts from Alert are already camping at Duliajan. The complex operation will include eight foreign experts besides the OIL and ONGC crisis management team.
“Meanwhile, the flow of gas from the well to nearby Early Production Setup (EPS) at Baghjan is being maintained with all operating parameters within desired level and safety measures in place,” added Hazarika.
Snubbing unit and the process
A snubbing unit is a hydraulic rig that can do everything a rig can do, plus it can perform under pressure in an underbalanced live well state.
Snubbing operation is a type of heavy-well intervention performed on oil and gas wells. It involves running the BHA on a pipe string using a hydraulic workover rig. Unlike wireline or coiled tubing, the pipe is not spooled off a drum but made up and broken up while running in and pulling out, much like a conventional drill pipe.
In oil parlance, the well is killed at the bottom by inserting pipes and pumping mud through this new pipe. Killing entails injecting artificial mud into the well at very high pressure to fill up the well and stop the gas from rising to the surface.
Due to the large rigup, it is only used for the most demanding of operations when lighter intervention techniques do not offer strength and durability. The first snubbing unit was primarily designed to work in well control situations to “snub” drill pipe and or casing into, or out of, a wellbore when conventional well-killing methods could not be used. Unlike conventional drilling and completions operations, snubbing can be performed with the well still under pressure (not killed). When done so, it is called a hydraulic workover. It can also be performed without having to remove the Christmas tree from the wellhead.
India’s longest well on fire since 150 days
The “blowout” occurred at the gas well number 5 at Baghjan oilfield, in the proximity of Maguri-Motapung Beel and Dibru Saikhowa National Park, while workover operations underway produced gas from new sand (oil and gas-bearing reservoir) at a depth of 3,729 metres. This caused natural gas and condensate oil gush to hundreds of feet in the air and spill all around.
The well caught fire on June 9 and has been raging since then.
OIL has 22 producing wells, 18 oil wells, and 4 gas wells at Baghjan Oil Field in Tinsukia district. These include the BGN5 well which is under fire.
Setback by NGT
A panel of the National Green Tribunal (NGT) said on Wednesday that OIL was operating the natural gas well at Assam’s Baghjan without required permissions when the uncontrolled escape of oil and gas, or blowout, began in May.
The panel has recommended legal action against the navratna PSU company and its officials over the violations that led to the blowout.
The panel led by retired Gauhati High Court judge Brojendra Prasad Katakey cited the violations. It said despite Supreme Court orders, OIL did not carry out a biodiversity impact assessment study for the Baghjan well as it is located near the Dibru Saikhowa National Park and biosphere reserve, which is home to 36 mammal species including tiger, endangered Gangetic dolphins, feral horses, and 382 bird species.
The panel said the OIL had also not taken environmental clearance from the Centre before starting drilling operations at Baghjan from November 2006.