ExxonMobil, the world’s largest listed oil company, said it was on course to cut its reported proved reserves by about 19 per cent, as it recognises the impact of lower prices.  In a statement in its third-quarter earnings release, the company said that if the low crude prices in 2016 persisted until the end of the year, then it would have to “de-book” about 4.6bn barrels of oil equivalent from its proved reserves, which were 24.8bn boe at the end of 2015.  Exxon also promised that at the end of the year it would carry out an assessment of the value of its “major long-lived assets” to see if any writedowns were needed.  Exxon delivered the warning on reserves as it reported a 38 per cent drop in its third-quarter earnings to $2.65bn. The results came at the end of a rough week for oil company earnings, with Total and Chevron reporting significant falls in profits for the third quarter, and Statoil and Eni reporting losses.  The announcement follows the news in September that the Securities and Exchange Commission, the US financial regulator, had begun an inquiry into Exxon’s reporting of its reserves and asset valuations.