Algeria has lost more than 60bcm in planned gas production since 2013 and will lose another 20bcm by 2020 due to project delays. It is relying on the giant Hassi R’Mel field to make up the shortfall. But the ageing field is showing the strain.

In 1956, two discoveries were made in the Algerian desert that were to change the course of the country’s history. One was Hassi Messaoud, a giant oil field in Ouargla province 550km inland and 300km west of the border with Tunisia. The...