US tight oil: Too light, too sweet

International buyers' appetite may start to wane in 2018

US light tight oil output is trans­forming world oil markets. After falling during the 2015 oil price crash, total American production - of which shale is now a major source - surged back onto markets, and the Energy Information Administration (EIA) expects output to rise an­other 0.5m barrels a day in 2018, to a record 9.9m b/d. Much of this new production is find­ing its way onto global markets, and exports now regularly run over 1m b/d. But can there be too much of a good thing? Specifically, with Opec's light sweet crude ex­porters Libya and Nigeria staggering back from extended production outages, and big Persian Gulf producers tightening availabilities of mid­dle-gravity sour crudes, i