I'm also afraid of this scenario, there are rumors of that Europe was having discussion in order to ban Russian imports. It would be the worst case scenario, it would send oil to the moon. Europe is importing 3 million barrels per day, that's a huge number that can't be replaced if lost.
It won't send Oil price to the moon if Russia is cut off from selling to EU if OPEC do a proper arrangement to members for them to increase supply and moreover Russia will still continue to sell to Asian countries which will reduce the demand from Asian countries. So I think it will still be a win and lose situation for EU/NATO and Russia consecutively. All the effort is to stop Russia from continuous invasion. The Ukraine president still asking for more sanctions and that is the reason for this Oil embargo on Russia.