 Complete the following phrase:  Oil exploration in Chad began in the 1950s while the country was still under French colonial administration. At least three oil rich areas were discovered in the country, however due to the high cost that would have been incurred in exploiting the finds, the French opted not to develop them. At the time the bulk of Frances petroleum was being imported from Algeria and the Middle East. In 1960, Chad achieved its independence from France, and François Tombalbaye took over the country as its first president. Tombalbaye enlisted Conoco, an American oil and gas company to search for oil reserves. The company found oil in several areas in 1973-1975, notably the Doba Basin in the Central African Rift system, and the Sedigui area of Lake Chad. In 1975, Tombalbaye was killed by soldiers in a coup détat and he was replaced with a military junta. This further intensified an already ongoing civil war between the government led by Goukouni Oueddei who became head of state of Chad in 1979, and Hissène Habré, the French and U.S.-backed former defense minister. During this period of especially heavy fighting, Conoco and other foreign oil companies suspended their oil exploitation efforts and left the country. Throughout the 1980s, very little was done to cultivate the petroleum industry owing to political instability, internal conflict, and the 