Yes, as I understand it the petroleum found does very little active management, but instead have a mandate to hold stock based on the FTSE Global All Cap Index.
Changing the mandate require approval by the parliament.
It does do active management in some asset classes. E.g. real estate purchases and the like. It also does buy or divest shares based on various other consideration, such as ethical rules. But you're right that they're investing according to a mandate set by government so they're limited in what they can do.
Changing the mandate require approval by the parliament.