Hassi Messaoud is a town in Ouargla Province, eastern Algeria, located 85 kilometres (53 mi) southeast of Ouargla. As of 2008 it had a population of 45,147 people, up from 40,360 in 1998, and an annual population growth rate of 1.1%, the lowest in the province. Oil was discovered there in 1956 and the town's prominence has grown rapidly since then; it is considered as the First Energy town in Algeria where all the big oil and gas companies have offices and bases. It is an oil refinery town named after the first oil well. A water well, dug in 1917, can be found on the airport side of town. Today there are over 800 wells within a 25 kilometres (16 mi) radius of the town.

Sonatrach is the national state-owned oil company of Algeria. Founded in 1963, it is known today to be the largest company in Africa with 154 subsidiaries, and often referred as the first African oil "major". In 2021, Sonatrach was the seventh largest gas company in the world.