How many gallons of diesel, per barrel oil, how many gallons of gasoline per barrel(low octane 87)...thanks?

Question

Low sufur sweet crude, out of the ground. Going on the premise that one would take a 55 gallon barrel and make only diesel, or low octane gas. I know that there are other products due to the refining steps.

Answer 1

First, petroleum barrels only hold 42 gallons, not 55.  

There is essentially no 87 AKI gasoline in crude oil.  The virgin naphtha from crude usually has an octane value of about 60 RON and slightly less MON so the AKI will be somewhere around 59.  To make even regular gasoline with an 87 AKI, this naphtha will need to be processed.

The virgin middle distillate, even from sweet crude, will probably contain to much sulfur to be used as diesel, thus it must also be processed, thus, there is really no diesel in crude oil either.  

A modern high conversion fuels refinery will end up producing about 20 gallons of unleaded gasoline from a barrel of crude oil and about 10 gallons of low sulfur diesel.  This yield pattern can be shifted somewhat toward diesel and away from gasoline if that is the fuels market the refinery is operating in.