Mbega has served in the oil and gas sector since 1997. Between 1998 and 2000, he served as Government Representative in the Equity of the State in the Products Sharing Contracts (PSCs) and further functioned as Presidential Advisor for Hydrocarbons. He also served as Secretary of State for Mines and Hydrocarbons from 1999 to 2003. He later became Vice Minister of Mines, Industry and Energy in 2003. He was appointed the Minister of Mines and Hydrocarbons of Equatorial Guinea on 21 May 2012 and was confirmed in office in June 2016, following a restructuring of the administrative instrument. He has also served as a member of the board of directors of three public energy companies in Equatorial Guinea: SONAGAS, SEGESA and GEPetrol. He continues to serve on the Advisory Board of Africa Oil & Power (AOP). His past positions, experience and initiatives has contributed to advancing the country's oil and gas industry to be one among the five largest in Sub-Saharan Africa. Equatorial Guinea has since 2017, become the 14th Global and 6th African Member State to be part of the Organization of Petroleum Exporting Countries (OPEC). He will be taking over as the president of OPEC in 2023.
