Craft, if you click
http://www.bbc.co.uk/news/uk-scotland-scotland-politics-20042070 a site offered earlier on this thread and look at the dark blue/purple shaded area, you'll see that - even in the highly unlikely event of Shetland becoming independent - a vast area of ocean would still be 'Scottish'.
None of it at all, of course, would be English, a point worth noting by those English ABers who are convinced they currently support Scots financially. You see, they would have no direct oil-income whatsoever!
As I suggested in my previous contribution here, this is precisely the area, to the West of Shetland, that exploration and finds are now happening.