An end to sanctions on Iran has driven global crude futures to 12-year lows and brought sub-$20-a-barrel oil in sight, although for some producers that is already a painful reality. This unfortunate group sells some physical crude cargoes at prices that are closer to $10 a barrel, thanks to an abundance of the “sour” grades they produce and a consumer base that favors higher-quality “light” oils from other origins. (Graphic: reut.rs/1ZGAl0s ) Producers of certain crudes from Mexico, Venezuela, Canada and Iraq are bracing for worse to come as Iran – now free of international sanctions – prepares to offload hefty supplies of heavy sour grades onto export markets. Some cargoes of heavy Mexican crude are trading for less […]