The Australian government described the Galilee Basin onshore in Queensland as a "good exploration target," noting it's been "a target of coal seam methane investigation."
The state government is considering proposals to transport coal from the Galilee Basin to northern ports for possible export to Asian markets.
Environmental advocacy group Greenpeace said plans for rail lines and port terminals for exports mean the Great Barrier Reef, a World Heritage Site, is in danger of becoming "industrial real estate."
Greenpeace said opposition to the plans is growing and the cost of pursuing alternative low-carbon energy solutions is declining.
In early March, the group said coal expansion projects planned for the Galilee Basin would lead to more port activity and dredging near the reef, which could destroy habitats for endangered species.
The advocacy group said it was working to prevent the threat from the coal industry.
"And we are standing alongside local communities, farmers and grassroots environmental groups to do so," the group said. "If there ever was a David and Goliath battle, this is it."