The two fields are about 550km from west-north-west of Darwin in water depths of between 350 and 400 metres.
BHP Billiton had a 32.61% stake in Laminaria and 25% in Corallina. The other joint venture participants are Woodside petroleum and Royal Dutch/Shell.
The Laminaria/Corallina stake is now held by Paladin’s wholly owned subsidiary, Paladin Oil & Gas (Australia) Pty Limited, which will set up an office in Perth in the next few months.
The acquisition is one of Paladin's largest to date. Paladin currently has assets in the North Sea in the UK, Denmark and Norway, as well as in Gabon, Indonesia, Romania and Tunisia.
"This is of an ideal size as a first deal for Paladin in Australia," said Paladin chief executive Roy Franklin.
"In addition we see the opportunity for follow-on deals in the country."
The deal would add about 13 million barrels 10% to Paladin's reserves base and increase its production by between 12 per cent and 15 per cent, according to Franklin.
Franklin has a strategy of selling assets when he believes he can get a good price, then investing in new areas, accroring to UK newspaper The Times.
While lining up its new Australian purchase, Paladin sold off its minority stakes in the North Sea’s Ross and Blake fields to Sumitomo, the Japanese trading house, for $75 million. Franklin said that the money he can get for North Sea assets lets Paladin seek better exposure elsewhere in the world.
Analysts said these transactions indicated Paladin was finding it hard to find affordable targets in the North Sea.
Seymour Pierce analyst Richard Slape told Glasgow newspaper, The Herald, that Paladin might be prepared to sell off other non-core interests to raise funds it could use to buy assets in places such as Australia.
Franklin has said he was not ruling out further acquisitions in Australia.
But Slape predicted that Paladin would not be moving out of the North Sea altogether.
The company’s current 50,000 bpd production target comprises 20,000 bpd from the North Sea’s UK sector, with another 20,000 bpd coming from assets in Scandinavian waters. Australia’s 6,000 barrels form the largest portion of Paladin’s “Rest of World” interests.