He was telling everyone who would listen that Norway would find oil, and needed to prepare itself.

> His was a lonely, contrarian voice. After examining exploration results, he wrote a report that warned Norway was sleeping, that even though no one had found oil yet, it was only a question of time. And time was short: the country’s leaders needed to prepare Norway to become an oil nation, but they were doing nothing. “I was a constant reminder that they were doing everything wrong,” al-Kasim says pointedly. Only his closest colleagues would listen.

I imagine he came to that conclusion only after he reviewed the exploration reports, maps, and other internal documents within the ministries.

I think he recognized from the exploration results that the local geology was very favorable even if they hadn't hit actual oil yet.