Algerian state oil firm Sonatrach has announced an eye-catching $50bn planned five year upstream spend for 2017-21. The figure is a slight increase on that for the most recent five-year plan, but a significant reduction compared to previous years.

Once plans to spend about $5bn/year downstream are added in, the total spending program comes out at about $75bn. Sonatrach’s headline figure for its 2016-20 five-year plan was $73bn, but for 2015-19 it was $90bn and for 2014-18 it was...