While most of the world is cutting back on oil investments, Saudi Arabia has quietly achieved a formidable feat of engineering – increasing its oil production capacity to a record 12.5m barrels a day.

The size and complexity of the five-year, $100bn (€70bn, £61bn) project are unmatched in the industry, as is Saudi Arabia’s willingness to postpone the gains the project will bring by keeping many of its oil spigots closed.