The amount of oil left in the North Sea is decreasing. As the price goes up, it may be economic to recover it. However as new fields are found (e.g. off Ireland) the the price may not rise enough to make it economic to recover it. There are too many unknowns to be able to make any reasonable guesses about how much tax any newly Independent Scotland would be able to raise via North Sea Oil & Gas.
The labour opposition is very good at the moment in working out how to spend a mythical bankers bonus tax. I reckon that they must have spent it a good 8 or 9 times. The same applies to the Scottish North Sea oil. It appears to being used by the SNP to cover all sorts of spending, from NHS to a Sovereign Wealth Fund, many times over. Added to the fact that the actual tax take varies hugely by year.
Add to the fact that Scotland has a high proportion of it’s people in Government employment and I am still not sure that the figures work out.
However all this is meaningless in terms of Independence. Scots should vote for or against Independence not on if they are going to be better off, but on if they want or don’t want it.
In any case the SNP has the problem that after the referendum they just become another left wing party. If Independence is granted then one of the main battle cries of Independence will have gone. Likewise if the lose the ballot, then perhaps the whole reason for their existence will vanish!
(As an Englishman, I can’t believe that S&O will leave Scotland if it became Independent.)