Karl Johnny Hersvik has always liked building things. With the Ivar Aasen field in the Norwegian North Sea due on stream soon and a freshly signed merger deal with BP Norway on his desk, the chief executive of Det Norske Oljeselskap is getting to do just that.

In front of a model of the Ivar Aasen platform at the company’s headquarters at Fornebu outside Oslo, Hersvik is more interested in finding errors than having his picture taken by Upstream.