Portugal is a small country. I did not see any serious investments going on, anything besides their "golden visa" program. A rich guy may invest 500k there to get his residency but serious cash is stored in the UK, Switzerland, Luxembourg, USA. But isn't this the case for most African countries?

OT: A much more interesting woman than Ms. dos Santos, also from Angola: https://en.wikipedia.org/wiki/Nzinga_of_Ndongo_and_Matamba

OT2: Actually most of the oil in Angola is in an obscure enclave: https://en.wikipedia.org/wiki/Cabinda_Province