Santos has brought forward plans to develop 300 coal seam gas wells across properties at Roma and Fairview to supply its Gladstone LNG plant in time for the planned start-up in 2015.
The 300 wells had previously been scheduled for development after 2015 and are part of the company's overall EIS approval to develop up to 2650 wells.
The company said the exact placement of the wells would be determined following geological and other scientific studies and consultation with landholders.
Santos has 640 agreements with landholders in place.
Santos said the extra $US2.5 billion in spending had been slated for after 2015 but was being brought forward in order to drill the extra wells before the end of 2015.
Gladstone LNG is one of several coal-seam-gas-to-liquified-natural-gas (CSG to LNG) projects worth $50 billion that are facing a raft of development challenges.
These include soaring costs due to skilled labour shortages, patchy drilling results, regulatory hurdles and potential competition from cheap US gas.
Developers of Australia's new gas export projects are under pressure to deliver, having sold most of the gas from the first phase of the three coal seam projects to Asian customers through long-term deals starting around 2015.
"The key challenge facing the CSG to LNG projects is upstream field deliverability in the early stages of project ramp-up," Santos chief executive David Knox said in a statement.
All three projects British Gas Group's Queensland Curtis Island LNG (QCLNG), Santos' Gladstone LNG and Origin Energy's Australia Pacific LNG (APLNG) have consistently held that they are on schedule to export gas between 2014 and 2015.
Last Friday, Origin announced it had finalised deal to supply about one million tonnes of LNG from its CSG fields in the Surat and Bowen basins to Japan's Kansai Electric Power Company over 20 years.
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