They already do this. It's the global fund that's reached $1tn, there's another side which is the Norway fund, though it actually limits to the Nordic countries

They already do this. It's the global fund that's reached $1tn, there's another side which is the Norway fund, though it actually limits to the Nordic countries and is a significant presence in that market. The Norway fund is worth a fraction of the Global fund, but I have no idea what proportion of oil revenues go into each.