Despite huge expense, advanced refineries at par with basic in earnings

As with almost every change in the oil market these days, the US shale boom had a role to play

Returns at sophisticated refinery units that companies built at great expense are now almost on a par with those at relatively inexpensive and simple plants.

In Asia, facilities with the ability to produce more gasoline and less heavy fuel — the typically sulfurous and viscous products used in ships and power plants — were suffering last month with lower margins than plants that don’t have such technology. The unusual shift in fortunes was spurred by shrinking profits from converting dirty residual oil into cleaner light fuel via a process known as cracking.

As with almost every change in the oil market these