"It happens that Libyan crude has almost no sulfur and produces a great deal of diesel fuel per barrel of crude, which means it is very valued," he says. "One can think of it as fat-free milk."It's a short (<4 minute) introduction to some of the intricacies of the energy markets and I suggest you listen to it.
Libyan oil is light and sweet — it's the kind that refineries want for making low-sulfur diesel, which is widely desired in Europe, and jet fuel, of which the U.S. makes a lot. Both markets require low-sulfur fuel because it pollutes less.