Income predictions for a Scottish share of oil and gas have decreased, new analysis shows.
The Scottish Government's own figures put the likely total between £2.9 billion and £7.8 billion in 2016/17, which could be the first full year of independence according to the SNP's timetable following a Yes vote in the referendum.
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The range compares with predictions made last year that North Sea revenue would be between £4.2 billion and £10.7 billion for the same period.
Scottish Finance Secretary John Swinney said the central prediction shows the country can benefit from £34.3 billion over the next five years - equal to almost £7 billion a year.
The Office for Budget Responsibility, which was set up by the UK Government, makes far lower predictions.
The body expects just £15.8 billion over the five years - less than half Mr Swinney's preferred scenario.
But Mr Swinney said: "The future outlook for the North Sea remains strong as demonstrated by the very high levels of investment in recent years, with capital spending reaching £14.4 billion in 2013 - more than double the level observed in 2010.
"The impact of that investment is now becoming visible. The latest statistics show oil and gas output in February and March 2014 was approximately 3% increased on the same months of last year."
His latest analytical bulletin, the third since March last year, puts revenue at £5.8 billion in 2014/15, rising to £8.3 billion, before fluctuating between £6.9 billion, £7.3 billion and finally £6 billion in 2018/19.
The new Scottish Government analysis accepts forecasts are lower than last year.
"This can be largely attributed to two factors," the report states.
"Firstly, operating costs are now projected to be higher in future years than was assumed in the first analytical bulletin.
"This in turn reduces the profitability per barrel produced.
"Secondly, future production and the oil price are now both assumed to be lower than anticipated in the first analytical bulletin."
Scottish Conservative leader Ruth Davidson MSP said: "The White Paper was already straining credibility as an uncosted wish-list but now even the SNP has been forced to admit that the oil figures they used to try and underwrite their fiction won't be achieved.
"While economic experts have been saying for some time that the figures for an independent Scotland don't add up, this is the first time that even Alex Salmond has admitted there's a multi-billion pound black hole.
"It is no wonder the Scottish Government stalled for so long on publishing these new statistics - the entire basis for their separation mathematics has been blown apart.
"All the experts advise caution when projecting oil revenues, even more-so when basing an entire economy upon it.
"Instead, even the SNP's most optimistic forecast falls short, leaving huge question marks over how to pay for public services like schools and hospitals in the event of separation."
Scottish Liberal Democrat leader Willie Rennie said: "As part of the UK we can share the ups and downs of this volatile resource across broader shoulders and better protect public services.
"The nationalists £2.9 billion downgrade to their most optimistic oil revenue forecast is a stark reminder of how volatile this source of revenue is.
"Even after slashing their optimistic oil forecasts it is still double that of the independent OBR. This would create tough decisions over tax and spend which Scotland would no longer be able to share across the UK's broad shoulders."