Australian resources firm Linc Energy said it had uncovered a huge oil deposit in the nation\'s vast outback in a discovery hailed Thursday by officials as worth some Aus$20 trillion (US$21 trillion). Linc said two independent reviews of its three deposits in central Australia\'s Arckaringa Basin had estimated there was up to 233 billion barrels of shale oil trapped within its rocks. \"Analysis presented in these reports indicates that the Stuart Range formation and the underlying Boorthanna and Pre-Permian formations are rich in oil and gas prone kerogen that may form the basis of a new liquids-rich shale play,\" Linc said in a statement. The announcement saw Linc\'s share price skyrocket 23.6 percent to close at Aus$2.67. However, officials cautioned that it was too early to say whether the oil could be profitably tapped, and the company sought to distance itself from the high-end valuations. \"Obviously if you want to stand up there and come up with $US100 (current value of a barrel of oil) times 100 billion barrels, you\'ll come up with a big number,\" Linc chief Peter Bond told Fairfax newspapers. \"(But) that\'s not how you value oil resources. We wouldn\'t put a valuation on it at this stage. It\'s too hard.\" Though playing down the Aus$20 trillion estimates, Bond said there was still estimated to be a minimum of 3.5 billion barrels of shale in the deposits, a size that was \"virtually unheard of these days.\" \"No matter how you look at it, it\'s big,\" he said, describing it as a \"multi-billion barrel opportunity\". \"Even stressing this number down to the minimum number the experts stress it down to, it\'s still a big story,\" added Bond. Linc said it had appointed Barclay\'s Bank to find a joint venture partner with shale oil expertise to help develop the deposit which it described as \"world class\" and comparable to the Bakken and Eagle Ford projects in the US. Tom Koutsantonis, mining minister in South Australia state, where the deposit is located, had earlier said the sheer amount of oil could be enough to see Australia become a self-sufficient net exporter. \"If the reserves and the pressure was right over millions of years and the rocks have done the things they think they\'ve done, they think they can extract vast reserves of oil out of South Australia which would have a value of about $20 trillion,\" said Koutsantonis. He warned that it was not yet known \"whether it was economic to recover or not\", with the oil trapped in \"low-permeability, clay-rich rocks\" that needed to be fractured to release the fuel. Crude oil, condensate and naturally-occurring liquefied petroleum gas account for six percent of Australia\'s total energy production, but represent 40 percent of consumption, according to the latest data. Australia\'s bureau of resource economics estimates that imports of oil will increase by an average 2.1 percent per year in the decades to 2050. The International Energy Agency has forecast that the United States will become the world\'s biggest oil producer by 2017 due to an explosion in hard-to-reach energy trapped in shale, or sedimentary rock.