Employees have been evacuated from a Timor Sea oil rig after an oil and gas spill 3.6km below the surface.
Oil and gas will continue to spill into the ocean from a drilling rig off Australia’s northwest coast for seven weeks, leaving a multi-million dollar clean-up bill for the company responsible.
About 40 barrels of oil are believed to have spilt in the initial incident, while condensate, a form of light oil, was also discharged along with gas.
Rig operator PTTEP Australasia said the incident happened about 4am (WST) on Friday on the West Atlas rig, operated by Norway’s Seadrill.
All 69 people on board the rig had to be evacuated and no injuries have been reported.
PTTEP announced it would engage another mobile offshore rig to drill a hole into the leaking oil well, pump mud into the hole and alleviate pressure to stop its flow.
Company director and chief financial officer Jose Martins told reporters in Perth on Sunday the plan had the ‘highest probability of success and the lowest risk’.
Mr Martins said PTTEP Australasia called in experts from around the world to determine how to bring the spill under control and minimise any environmental damage.
Under the plan, a mobile drilling rig called the West Triton would be deployed from Singapore on Tuesday.
A sister rig to the West Atlas, and also owned and operated by Seadrill, it is expected to take 20 days to be towed by boat to the site of the spill.
Mr Martins explained the West Triton would be placed about two kilometres away from the West Atlas and a relief well drilled into an intersecting pipe.
He said this could take up to four weeks to complete and then heavy mud would be pumped into the hole to stem the flow.
Mr Martins would not speculate on what caused the leak 3.6 kilometres below the surface.
The well bore had been plugged with about 20 metres of mud and cement and ‘we’re not sure exactly what caused any fracture or any leakage’, Mr Martins said.
He said the company was still investigating and would have a better idea once it had inspected the area.
In the meantime, the Australian Maritime Safety Authority (AMSA) has begun mopping up the spill, which it said has grown to about 14 kilometres long and 30 metres wide.
On Sunday a Hercules military transport aircraft dropped chemicals to soak up the oil slick, which AMSA spokeswoman Tracey Jiggins said would be very expensive and could ‘run into the millions’.
A two nautical mile exclusion zone for aircraft remains in place around the rig.
PTTEP has shut down the Montara development, due to come online later this year, while the spill is investigated.