It must have seemed like a good idea at the time. When the Russian energy giant Gazprom set up a joint venture with a Nigerian company to develop natural gas resources in Nigeria, they chose a name that from the point of view of Russian seems obvious and unexceptionable: Nigaz, i.e. Nigeria + Gaz. They would have expected to pronounce it in Russian as ˈnʲiɡas, -ɡəs and in English as ˈnaɪɡæz.
As commentators pointed out, it seems unlikely that an English speaker was in the room when they chose it — even though all educated Nigerians speak English.
Because the natural way to read this spelling in English is as ˈnɪɡəz, just like niggers. And that is not a respectful way for the Russians to refer to their African partners.

‘Nigaz’ is yet to feature on Gazprom’s website, which does confirm the formation of its partnership with NNPC but interestingly, offers no name for the new enterprise.

I blame the ambiguity of the English spelling system, where the letter i can often arbitrarily stand for aɪ or ɪ. Just like in the word(s) wind.