Proven, Probable, Possible, and Contingent Natural Gas Reserves: A Concise and Holistic Review of Major Critical Developmental Steps

Abstract Petroleum Motor Spirit, PMS, product subsidy removal in Nigeria has led to a significant increase in commodity prices in the market. Other African countries, notably South Africa and Senegal, have faced and are still facing energy deficit-related crises. Some causes of energy-related problems in Africa included dysfunctional refineries in Nigeria, inadequate energy planning for economic growth, social advancement in South Africa, and exponential population growth. Despite all these energy-related problems, gas flaring persists in Africa. To solve the energy problems as identified, investigations were carried out on the suitability of leveraging natural gas as a lasting solution. Natural gas as a clean energy source gained additional prominence in 1973 in response to the Organization of Petroleum Exporting Countries, OPEC, grips on oil production and quota system. That is, PMS subsidy removal should also put more pressure on natural gas. So, proven, probable, possible, and contingent natural gas reserves and resources should be properly examined. By proven gross reserves-to-production ratio, it will take Africa 88 years to deplete, second to the Middle East with 100 years. The probable, possible, and contingent resources, combined have higher capacity. The formation, transportation, and accumulation of natural gas in sedimentary basins take millions of geologic years, is nonrenewable, and cannot be found everywhere. Whenever found, they are categorized. Several mathematical models such as the Duong method, Logistic Growth Model, Stretched Exponential Decline, Power Law Exponential Decline, Modified Hyperbolic decline, material balance, and modified Arps’ decline model were developed to model unconventional and conventional natural gas reservoirs. The available technologies with all the mathematical model simulations, coupled with an enabling environment, are enough to meet African energy demands from both unconventional and conventional natural gas reservoirs.