River bubbles burst
THE Condamine River gas bubble issue may just have burst, with methane gas seeps falling to the lowest levels recorded, according to Origin Energy.
Measurements from Origin show in December 2017 the flow of gas from the river seeps dropped by more than 90 per cent from the peak rate of almost 2000 litres per minute recorded in January 2016.
Origin Energy regional manager Tim Ogilvie said the company had implemented a solution as a result of monitoring and research done since the phenomenon was brought to their attention in 2012.
"This work pointed to the seeps being part of a geological migration pathway,” Mr Ogilvie said.
"The potential solution was to intercept and produce the gas before it reaches the river, effectively taking it out of the system.”
As a result, Origin drilled three specifically designed wells and a monitoring bore in June 2016, with the wells going online in December that year.
In June 2017, 12 further gas wells drilled directly south of the river were brought into production.
"That work, in addition to regional production activity from CSG producers, appears to have led to there being less gas available in the region and therefore there's less bubbling up through the river,” Mr Ogilvie said.
"(The decline) would be a combination of those factors, being the work that we've done on those intercept wells... and also regional production as well as natural factors... but we expect all of that work that we've done locally and regionally to be contributing to the decline in those seep rates.”
Work on a further 14 production wells, and eight wells designed to intercept the gas heading towards the seeps, started last month.
But Basin Sustainability Alliance chairman Lee McNicholl said while the interceptor wells might have reduced the gas seeps, there were potential negative effects down the track.
"Origin's interceptor wells, while reducing the river bed bubbles to a politically acceptable level, potentially conceal a more disastrous long term scenario,” Mr McNicholl said.
"This is the possible sucking of water out of the river through the same pathway once the gas flow is controlled.”
Mr Ogilvie said the work had been praised by landholders.
"It's been very positively received in terms of the local landholders that we consult with who live in the region, and it's been a positive validation of the research program that we've been going through for the last few years.”