Saudi Arabia is preparing to lift the lid on one of the global energy industry’s most closely guarded secrets as it prepares to sell shares in Saudi Aramco — how much crude lies beneath the desert kingdom’s sands.  “This is going to be the most transparent national oil company listing of all time,” Khalid al-Falih, Saudi Arabia’s energy minister, told the Financial Times in an interview.  Ever since the kingdom completed the nationalisation of the formerly US-controlled Saudi Aramco in the 1980s, the size of proven reserves of the world’s largest oil exporter have remained consistently around the 260bn barrels mark, according to officials. But the profiles of oilfields and reserves estimates have remained a source of intrigue among international energy executives and investors who have been unable to verify the government’s figures. Mr Falih said independently audited numbers would soon be disclosed.  “Everything that Saudi Aramco has, that will be shared, that will be verified by independent third parties,” he said, adding this would include financial statements, “reserves … costs [and] profitability indicators”.