Was curious, so I did a 30 second search:

"The US Geological Survey estimates that onshore northeast Greenland (including ice-covered areas) contains around 31 billion barrels of oil-equivalent in hydrocarbons – similar to the US’s entire volume of proven crude oil reserves."

Source: https://theconversation.com/greenland-is-rich-in-natural-res...

Another 30 second search would show you that their oil is not readily available and is unproven. Otherwise Denmark would already be an even wealthier petrostate like Norway.