Hydrogeochemical advice for the Narrabri Gas Project

Santos Energy NSW

We were enlisted to sample and analyse the groundwater within the Gunnedah Basin south-west of Narrabri in New South Wales, and to explain groundwater flow and processes in and around the area.

The project was conducted to support coal seam gas exploration by Santos Energy NSW within the Gunnedah Basin. To extract the gas, bores are drilled through the local intake beds of the Great Artesian Basin and care must be taken not to disrupt the isolation of these two sedimentary basins during any future proposed gas production.

We were able to identify and characterise the different groundwater sources and particularly distinguish the Coal Measures waters (a stratified geological formation containing both coal and coal seam gas) from shallower productive aquifers of the Great Artesian Basin. This helped to determine how we might identify potential preferred groundwater pathways and possible signs of leakage between the different aquifers in the area. Using a combination of chemistry and isotopes, the different formations can be distinguished and key markers and tracers can be used to ensure that no interactions are taking place.

Our expertise on the Great Artesian Basin is also being utilised to educate the general public of the hydrogeological relationships in the area and how Santos Energy NSW plans to protect the local water resources.