"Through to 2040 it's the fastest-growing energy source and that's why there's such demand for our product across Asia," he said.
Santos and ConocoPhillips have a long-standing business relationship, with the latter operating Santos' natural gas assets in northern Australia for a number of years.
The deal, which requires regulatory approval, would see ConocoPhillips exit all of its northern Australian operations. However, its investment in an LNG plant in Queensland would be unaffected.
"The acquisition of these assets fully aligns with Santos' growth strategy to build on existing infrastructure positions while advancing our aim to be a leading regional LNG supplier," Mr Gallagher said.
"This acquisition delivers operatorship and control of strategic LNG infrastructure at Darwin, with approvals in place supporting expansion to 10 million tonnes per annum and the low-cost, long-life Barossa gas project.