In 2011, AGL began injecting and storing gas underground at the depleted Silver Springs/Renlim reservoir in the Bowen Surat Basin in central Queensland. AGL provides the storage for balancing gas supply in their domestic portfolio.
The Silver Springs/Renlim gas field produced gas from 1978 to 1999 for the Brisbane market. Gas production finished in 2000 when the reservoir was fully depleted.
Since then, the shale-capped reservoir – which naturally prevents gas from escaping – has proved to be ideal for underground gas storage.
The Silver Springs/Renlim underground gas reservoir sits about 1.9 km below the surface and about 500 m below the deepest known aquifer bearing sandstones in the Great Artesian Basin. Above it, a thick layer of impermeable cap rock has acted as a gas-tight seal for millions of years. The impermeable cap rock also prevents the injected gas from migrating into the Great Artesian Basin.
All gas wells drilled into these fields are isolated from aquifers with steel casing and cement grouting to prevent any connectivity between the gas reservoir and the Great Artesian Basin.
Water quality, reservoir pressures and gas-water contact movements are monitored as part of a comprehensive reservoir management plan.
Gas from the Silver Springs storage facility and other natural gas fields in the region are sent to the Wallumbilla LPG plant via a 100 km long pipeline.
AGL acquired the existing Wallumbilla Liquefied Petroleum Gas (LPG) facility from Santos QNT Pty Ltd in April 2011. The project is about 13 km south of Wallumbilla and 42 km east-southeast of Roma in the Darling Downs region of Queensland.
AGL extensively refurbished the LPG facility between 2011 and 2015 and it was put back into service in May 2016. The facility removes propane, butane and condensate to provide sales-quality gas for input into the Roma – Brisbane pipeline where it is distributed to domestic and commercial customers.
A new Environmental Authority (EA) in accordance with Chapter 5A of the Environmental Protection Act was required to operate the facility. The EA was granted in 2013 and was subsequently updated in 2016. As part of AGL’s ongoing commitment to improving operations, the EA is currently being reviewed.