Fuels, Lubricants, Natural Gas Eni is currently present in Nigeria with the activities It was the first International Oil and Gas company operating in Nigeria to do so. In addition to its activities in the Upstream sector, Eni has also made critical Upstream is generally the most lucrative aspect of oil and gas business but it is also by far the most capital intensive. We have supplied the list of E & P companies in Nigeria below. Downstream companies: Downstream business involves marketing and distribution of fuel products after they have been refined. All the filling stations, lube plants, domestic gas sales outlets are all into downstream activities.