The Montara oil spill is an oil and gas leak and subsequent slick currently floating in the Montara oil field, Timor Sea, off the northern coast of Western Australia. It is considered one of Australia's worst oil disasters. The slick was released from the West Atlas mobile rig which began leaking oil on August 21, 2009, and continued leaking until November 3, 2009, when the leak was stopped by pumping mud into the well. The West Atlas rig is owned by Seadrill, and operated by PTTEP Australasia, a subsidiary of PTT Exploration and Production (PTTEP) which is in turn a subsidiary of PTT the Thai state-owned oil and gas company. The rig is located off the Kimberley coast, 250 km (160 mi) north of Truscott airbase, and 690 km (430 mi) west of Darwin. Sixty-nine workers were evacuated from the rig when oil and gas began leaking.
The Australian Department of Resources, Energy and Tourism estimated that the Montara oil leak could be as high as 2000 barrels/day, five times the 400 barrels/day estimated by PTTEP Australasia. After flying over the spill site, Australian Greens Senator Rachel Siewert claimed the spill was far greater than had originally been reported. WWF-Australia also claimed that the spill was worse than originally expected.
The first four attempts to plug the oil leak by PTTEP failed, but the fifth attempt succeeded on November 3, 2009, when PTTEP pumped approximately 3,400 barrels of mud into a relief well to stop the leak.
On November 1, 2009, during an attempt to plug the leak, a fire broke out on the West Atlas oil rig. On November 2, PTTEP said that the rig fire appeared to be burning off the oil and thereby preventing further leakage into the sea. The fire was largely extinguished when the leak was stopped. PTTEP said that once safety criteria have been met, a specialist team will board the West Atlas oil rig to assess the damage and determine the best strategy to plug the well.
Another gas leak began emanating at the East Puffin field in early September 2009, about 50 km (30 mi) from the Montara field. Reporting of the East Puffin leak was delayed by two months from when it was first observed. It is not known if this gas leak is associated with the Montara leak.
The leak initially emanated from the West Atlas mobile oil rig on August 21, 2009. Sixty-nine workers on the rig were evacuated. By August 24, the oil slick resulting from the spill was estimated to be 14 km (9 mi) long and 30 m (100 ft) wide. On August 29, the slick was estimated at 180 km (110 mi) at a minimum, measured east to west.
By September 3, 2009, the Australian Maritime Safety Authority (AMSA) reported that the slick was 170 km (106 mi) from the coast of Western Australia, and moving closer to the shore. The slick was also reported to have spread over 6,000 km2 (2,300 sq mi) of ocean with evidence that the oil is killing marine life. Reports that the slick had spread to within 120 km (75 mi) of the Northern Territory coastline were dismissed as incorrect, with the AMSA stating that the discoloured water was likely to be a natural phenomenon, such as an algal bloom or coral spawn. However, by October 30, 2009, PTTEP acknowledged that the spill had spread as far as Indonesian waters, but had not reached the coast.
On August 23, 2009, a Hercules aircraft sprayed 10,000 litres of chemical dispersant onto parts of the slick, with ongoing aerial spraying with dispersants being the primary early response to the spill.
The West Triton mobile drilling rig arrived at the West Atlas oil rig in an attempt to plug the oil leak on September 11, 2009. PTTEP Australasia initially said it could be just days before the leak was brought under control, but then said that the oil leak would continue for eight weeks until they could bring in another mobile offshore rig, West Triton, to drill a hole into the leaking oil well, and pump mud in to alleviate pressure to stop the oil flow. Oil and gas producer, Woodside Petroleum Ltd offered to assist PTTEP in cleaning up the oil spill with the use of a rig closer to the spill site. However, PTTEP rejected the Woodside offer on the basis of "safety reasons". On September 6, the plugging of the oil leak was delayed further by a broken towline to the mobile oil rig being towed in from Indonesia by PTTEP. On September 7, the Australian Federal Government announced that it was suspending the normal approval process to fast track stopping the leak at the West Atlas oil rig.
On November 1, 2009, the West Triton rig successfully drilled the relief well to intercept the leaking well. During operations to kill the leak by pumping heavy mud down the relief well, a fire broke out on the West Atlas oil rig. This was expected to delay further work on resolving the spill. All eight non-essential personnel were taken off the West Triton rig.
On November 3, 2009, the fifth attempt to stop the oil leak succeeded. Approximately 3,400 barrels of heavy mud were pumped down the relief well which intercepted the leaking well on November 1, 2009. PTTEP continued to pump a mixture of light mud and brine into the relief to maintain a stable condition. Since the leak had been killed, the main fire on the rig had also extinguished. Some material on the topside of the West Atlas rig remained on fire but had extinguished by November 3, 2009 as the fuel source burnt out.
Once safety criteria is met, a specialist crew from ALERT Well Control will reboard the well head platform to assess the damage and determine the best strategy to plug the well. Once the well head platform is secured, specialist personnel from Atlas Drilling may attempt to board the West Atlas rig to assess the damage caused by the fire.
PTTEP estimates that it has spent $170 million on the gas and oil leak up to November 3, 2009. The environmental clean-up cost $5.3 million.
Biologists said that the effects of the Montara oil spill could be catastrophic for marine ecosystems, with claims that although it is a lightweight crude oil spilling from the platform, it can still have toxic effects on birds, marine invertebrates, coral and marine algae. The Wilderness Society described the area as a "marine superhighway", and whales and endangered flatback turtles observed in the area are at risk from the spill. By September 3, 2009, fishers observed sick and dying marine life, and an absence of birds in the spill area. The World Wildlife Fund (WWF) observed spinner dolphins, sooty terns, spotted sea snake and threatened hawksbill and flatback turtles swimming in the oil slick, and expressed concern about long term effects. WWF also observed a wax-like residue from the oil spill.
On November 10, video emerged of Indonesian fisherman and scuba divers holding dead fish whilst in the water amongst the oil slick. The footage was apparently taken whilst in Indonesian waters.
PTTEP stated shortly after the leak was plugged that they had a theory about the cause of the leak but would not disclose nor confirm the cause until they had access to the West Atlas rig and could present a thorough appraisal.
On November 5, 2009, a Commission of Inquiry into the oil leak was announced. The inquiry, led by David Borthwick, will have the power and authority of a Royal Commission. The report is to be presented by the end of April 2010.
NGOs in Indonesia expressed concern about the oil spill's effects on the Indonesian environment and traditional fishing grounds as the oil spill drifted towards the islands of Timor and Sumba. Montara oil field is situated south of Indonesia's Pasir Island, a popular fishing location for many East Nusa Tenggara fishermen. By early November there were reports of dramatic declines in the number of red snapper caught by Indonesians, with 7,000 fishers being affected by income loss. East Nusa Tenggara governor Frans Leburaya said Australia and the operator of the oil field should be responsible for any environmental damage caused by the oil spill. Fishers in West Timor are reported to be going bankrupt because of the oil spills effects on fishing stocks.
East Timorese President, Dr Jose Ramos-Horta, said that the Australian government and the Thai company that own the platform are responsible for the spill, and that he will seek compensation for damage caused by the spill to his country's environment. Ramos-Horta called for Australian environmental organisations to help assess if the spill has caused damage to East Timor's maritime area.