The Niger Delta is a useful coastal anchor, with distributary channels entering the Gulf of Guinea. Inland, the Niger and Benue meet at Lokoja. Finding that confluence gives you a relationship between two rivers that is more specific than a broad band of green vegetation.
Checking the location
Trace the coast west toward the Lagos lagoon system, then compare the delta with the inland river network. Wetlands and dense settlement also occur elsewhere in West Africa. Neither a large city nor an apparent gas flare establishes a country by itself, and ordinary daytime imagery cannot support claims about night-time lighting.