We are continuing to refine and adjust how we manage and mitigate the seeps in the Condamine River.
Targeted intercept and development work adjacent and to the south of the river is having a positive impact in significantly reducing the seeps.
This approach involves a combination of coal seam gas production wells specifically designed to intercept shallow gas migrating towards identified natural geological faults that are providing pathways to the seeps in the river.
Using methodology developed by CSIRO, regular gas flow measurements at the main seep location continue to be taken. The flow of gas, or flux, is measured by placing floating capture apparatus over the seeps in a defined grid pattern and measuring the amount of gas collected in a defined time period.
The results are presented in the graph below. Volumes are shown in litres per minute averaged per quarter, since Q1 2015.
Dec 2011: Condamine River experiences major flooding, heavily scouring the riverbed.
Apr 2012: Condamine River seeps are identified. Historical evidence of shallow gas and natural gas in the area is well known. There is no coal seam gas development in the immediate area.
Aug 2012: Origin, an upstream operator for Australia Pacific LNG, initiates a long-term monitoring and research program and independent technical review by international scientific experts into the phenomenon.
Sep 2013: CSIRO develop a method to measure the flow rates at the main seep
Nov 2013: Several monitoring bores are drilled nearby as part of ongoing studies
Feb 2014: Independent technical review (Norwest) finds several possible factors may be encountering, including the underlying geology, natural events such as drought and flood cycles as well as human activity (water bores and future coal seam gas development)
Jan 2014: Increasing seep flow rates are observed. Regular measurement of flow rates begins using methodology developed by CSIRO
Jun 2015: Several hoods are installed underwater to capture and safely vent the gas and provide additional real time monitoring
Jan 2016: Flow rates at the main seep peak at almost 2,000 litres a minute
Apr 2016: The seeps are deliberately lit with claims large scale CSG development nearby and ‘fraccing’ is the cause (despite no gas development in the area and the nearest fracced gas well being over 15km away). The actions gain widespread attention.
Jun 2016: Informed by research, local seismic studies and technical review recommendations, three specifically. designed wells and a further monitoring bore are drilled as a first step towards intercepting and reducing the amount of gas heading towards the river.
Aug 2016: Seep flow rates begin to fall.
Dec 2016: Three intercept wells come online, providing valuable insights to the management of the seeps and future development in the area
Mar 2017: Seep flow rates fall significantly
Jun 2017: Twelve gas wells drilled directly south of the river are brought onto production
Oct 2017: Seep flow rates fall sharply to 158 litres per minute, around a quarter of the first flow rate measured back in 2013.
Dec 2017: Measurements confirm the downward trend and a reduction of over 90% compared to the peak in early 2016. Work commences on a second development package of gas wells adjacent to the river made up of 14 production wells and eight wells specifically designed to intercept gas heading towards the seeps through an identified natural fault and pathway.
Feb 2018: Measurements confirm a continued reduction in seep flow rates to around 100 litres per minute
Apr 2018: Increased flow rates begin to be observed as the 12 gas wells south of the river come off line for maintenance and upgrade work, reducing their mitigating effect
Jul 2018: Flow rates plateau around 1,000L/minute as these wells are progressively brought back to production.
Sep 2018: Flow rates fell dramatically after the second, larger package of mitigation wells immediately adjacent to the seeps come on-line. Gas is intercepted and directed into gathering lines as part of regional gas production
Oct 2018: Seep flow rates of around 50 litres per minute are recorded, the lowest level measured to date.