Natural gas and water are held in the coal seams by pressure. To extract natural gas from coal seams, water is extracted from the seam. This releases the pressure allowing the natural gas to flow up through the well to the surface.
The water extracted is not the same water accessed by agriculture and community bores and is also not taken from the Great Artesian Basin. In the Narrabri area it comes from the coal seams located 500 to 1,200 metres below the surface.
The water extracted in the Narrabri area is about half as salty as seawater; too salty for stock use or irrigation unless it is treated.
Before we take any water, we must have a Water Access Licence in place; just like other users. This water must be obtained, and paid for, from the market. Our water extraction is also assessed against the Government’s Aquifer Interference Policy.
Currently, water from our exploration wells is being transferred from the field via an underground flow-line to double-lined ponds at our Leewood facility, adjacent to the Pilliga.
The water is then desalinated at a reverse osmosis facility at the site and, once it meets Australian irrigation standards, is being used to irrigate a lucerne crop planted on the Leewood property.
Santos estimates about 80% of the water extracted as part of the proposed Narrabri Gas Project will be able to be reused following treatment for irrigation, dust suppression and construction activities.
The salt waste product is classified as general solid waste under the NSW Waste Classification Guidelines.
Santos will manage the salt in a safe and sustainable manner and in accordance with all regulatory requirements.
Santos will seek regulatory approval to sell the remaining salt commercially or dispose of the salt to a licensed landfill if no buyer can be found.
Because of the depths at which we are working, we don’t anticipate any impact on local bores but, as standard practice, we offer to monitor the bores of landholders within a 2km radius of our operations. This gives the landholders added confidence our work isn’t impacting their water.