I suppose the amount of oil is too small to have a significant impact on supply and prices. A large share of the GDP of OPEC countries is based on oil, such as primary extraction and shipping. Oil varies in type and quality. Crude oil needs to be refined, for example to remove impurities like other elements.

I’d say both yes and no.

Not as dependant on it to completely hit the definition, but it’s still a relatively high source of income.
The big difference is that our income is invested globally through Oljefondet (Statens Pensjonsfond Utland), so today we are much more vulnerable to financial instability than we are to fluctuating oil and gas prices.

Export prices are not that high as there are pipelines in the North Sea and relatively short trips to our European neighbours, but our extraction price is on average about twice that of e.g. Saudi, at about $20-25 per barrel vs $10.
Still a lot lower than in the US and UK.

Another upside is that the North Sea oil is relatively light and sweet, making it easier and cheaper to crack into sellable products.

Hope I answered all your questions, if not just ask again.

Yes-ish: While petrol is one of the main exports the state budget isn’t (overly) reliant on it. The amount of the state budget that can be covered by petroleum money is limited by law to a few percent, and changing this percentage requires a supermajority. In short, this is to avoid Dutch Disease, and also ensuring that the income from petrol exports aren’t spent all at once - instead it is saved up and has accumulated into the world’s biggest pension fund.

And no, the export isn’t very expensive. North Sea oil (Brent crude) is pretty easy to refine.

Source: Am norwegian