I do not know why my country, Nigeria, has caught Trump's eye. Obviously I'm not buying his lie that he's a crusader for Christianity, but I suspect that that might be something to do with it. The US Right has held Nigeria up as an example of the "Christian genocide" for years, so maybe he's playing to that crowd.
I'm not jumping to the conclusion that it's oil. America and Nigeria produce similar oil types; in fact, Nigeria is a net importer of US oil, not exporter.