The search for oil in the Niger Delta started in 1937, onshore as well as offshore. The reserves are estimated to an amount of 200,000 bbl/km2
There are five major reserves and they are aligned in a belt, the prolific belt. This belt lays exactly between the sea and coastline of Nigeria. This zone is a transition zone between the oceanic and continental crust, thus a weak zone due to tectonic activity. Together with a hot geothermal belt at the delta center and young sediments this place is the perfect place for the oil industry. The oil is much deeper in the continental crust than in the oceanic crust, this is why they also dig for oil in de ocean.
Nigeria also gets energy from a thermal power station that is using oil and gas.
In the map is shown that there are a lot of places where they dig for oil and gas, offshore and onshore. The map also shows places where there were oil spills due to shell.