Santos gas wells off the coast of WA have been leaking methane for a decade, yet no authority is fixing it

By Abha Haval

A number of wells at the Legendre field have been leaking methane gas for the past decade off the coast of Western Australia with no signs of fixing the wells from gas producer Santos or the government, causing the waters to get polluted.

The Legendre field wells located 105 kilometers north of the Pilbara port of Dampier, were first found leaking by an underwater remotely operated vehicle in 2013, two years after they were permanently sealed.

The Legendre project had ceased production in 2011 and Santos took over management in the 2018 Quadrant Acquisition from former operator – Apache, when the wells were decommissioned. Santos continued with the program including regular surveys with one recently conducted in 2022 when NOPSEMA (offshore energy regulator) altered the plan from fixing the seepage and proposed to monitor the fields for another five years.

NOPSEMA spokesperson told City Hub that they regulate and monitor operational and temporary abandoned wells but have no regulatory authority to monitor the integrity of wells permanently abandoned under a previous regulatory regime of designated authorities.

Currently, NOPSEMA regulates 873 offshore gas wells overall of which 457 are operational, and 326 are shut-in, suspended or temporarily abandoned.

The spokesperson said, “There are 90 wells that are plugged and abandoned and are awaiting the final abandonment report pending acceptance.”

NOPSEMA could not comment on specifics while the plan in under assessment.

Evidence of methane gas leak

Friends of the Earth Offshore Fossil Gas campaigner Jeff Waters is concerned that “nobody is monitoring the wells and we don’t know how many of the abandoned 90 wells are leaking.”

“NOPSEMA came into picture in 2012, until then there was no government organization monitoring them and there was no jurisdiction over the wells,” Waters said.

“This is just one example. We don’t know how much methane has been leaking for 10 years.”

“Methane gas is 80 times worse than carbon dioxide for the environment. When bubbles emerge from the gas, the water gets coated with oil residue. That much proportion of methane going from the surface of water to the shoreline is toxic and can kill the sea line (biodiversity).”

Santos engaged with CSIRO last year to undertake an in-depth monitoring program.

A spokesperson for Santos said, “Findings to date show that the gas is non-toxic and unlikely to present an environmental hazard.”

A report by Peter Milne for the Nine newspapers mentions, “In 2021, gas bubbles up to 10 millimetres in diameter were measured leaking from 26 locations in the fields at the rate of 187 cubic metres a year.”

“Gas is leaking from two separate wells and a group of 20 wells that were covered with heavy mats after being abandoned.”

“The government has known about this for years, and methane is still not counted in the national greenhouse emissions,” Waters said.

“The oil and gas companies have been in power and running the politics, and the government is not doing anything.”

“The materials degrade over time and there are more than 100 wells that need to be decommissioned. This will not happen until the oil companies or the government takes responsibility for the wells.”

Santos told City Hub that they are currently implementing a management plan that includes a regular monitoring program.