For example, despite Kal'tzhar's claims here, the UK's oil production cannot support, say, all of Europe. Iran, being the second largest OPEC producer, can generate a far larger supply. In fact, by not buying Iran's readily available oil, demand goes up as alternate sources begin to be tapped. As demand goes up, so do prices (law of supply and demand) for a highly sought after good.
I'm well aware of the limits of the UK oil supplies....I would never claim that it could supply Europe, it can supply itself, just and some extra but thats it.