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Katherine Clyne

ExxonMobil’s Plans to Decommission the Bass Strait oil and gas structures. What does International Law say?



Oil production, the decommissioning of plants, and all other aspects which provoke legal responses make oil arguably one of the most contentious areas of international and domestic law. Australia has recently faced a new legal problem in the area. ExxonMobil has set forth a plan to abandon its Bass Strait Oil and Gas structures, raising questions over whether ExxonMobil would be in violation of international law in its environmental threats. Specifically, with reference to the articles of the 1958 Geneva Convention on “The Continental Shelf”. 


First discovered in the 1960s, construction in the Bass Strait has continued from 1969 through to the 2010s, with 23 offshore platforms and installations currently in operation throughout the Strait. The offshore fields are connected by some 600 km of pipeline networks, leading to onshore processing plants in Longford, Victoria.


According to ExxonMobil, the Bass Strait oil field remains the largest oil field discovered in Australia.  “To date, more than four billion barrels of crude oil and around eight trillion cubic feet of gas have been produced. And our future remains bright - with Bass Strait continuing to supply vital energy to Australians for more decades to come,” states ExxonMobile’s website, emphasizing the sheer scale of production emerging from the Bass Strait region. 


The quantity of platforms in the Strait, therefore, makes Exxonmobile’s decommissioning plan a sensitive environmental matter.  According to the Geneva Convention on the Continental Shelf (1958), article 5:


“Due notice must be given of the construction of any such installations, and permanent means for giving warning of their presence must be maintained. Any installations which are abandoned or disused must be entirely removed.”


This implies that ExxonMobil's plan to leave some structures, stands in violation of the relevant international law on the continental shelf and environmental protection of the ocean. 


Professor Donald Rothwell, a specialist in international law at the Australian National University, told the Guardian, the “Bass Strait was used for international navigation and had special status under the UN convention on the law of the sea and related International Maritime Organisation guidelines.”


Therefore, as a member of “Unclos” (United Nations Convention on the Law of the Sea), the Australian government was mandated to remove all structures that are not in use from the Bass Strait. However, in September of 2024, ExxonMobile maintained that “lower sections of steel structures in deep water would remain, with removal “part of a future decommissioning campaign, unless an alternative end state is proposed and accepted by the regulator”.


So what comes next? ExxonMobile will submit their full plan in early 2025 and will require separate approval from the federal Department of the Environment under the Environment Protection Act to abandon infrastructures on the seabed.  Rothwell further informed the Guardian: “This is a novel issue that hasn’t arisen legally in Australia before,” adding that, “the government was well aware of the importance of the UN convention, as well as Australia’s rights and obligations”.


The decommissioning of oil and gas structures off the coast of Australia will present one of the first cases, wherein the Australian federal government must demonstrate if they will uphold their obligations under the UN Convention. 


This is a developing story as ExxonMobil prepares its final plans, but it is certain that the international legal community would attempt to hold Australia accountable for mandating the full removal of offshore structures.


Image by Dietmar Rabich via Wikimedia Commons


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