Complex sentence: He served as Minister of Mines and Energy until 1984, when he became Minister of Mines and Oil; in the government named on 13 August 1989, he became Minister of Secondary and Higher Education, in charge of Scientific Research.
Split into simpler sentences: He served as Minister of Mines and Energy until 1984, when he instead became Minister of Mines and Oil. In the government named on 13 August 1989, he was moved to the position of Minister of Secondary and Higher Education, in charge of Scientific Research.