The oilfield has a lot of funky units...the reason "bbl" is used to
abbreviate "barrel" is this:

After the first oil well in the US was drilled in Pennsylvania, they were
having trouble with the barrels they hauled the oil in.  So the guys checked
the barrels for holes, and the ones that were good, they marked with a blue
"X."  So the abbreviation "bbl" actually stands for "blue barrel."

A barrel is 42 gallons because they used to haul the oil in 50 gallon
barrels over bumpy roads.  The oil would slosh out of the barrels on the
way, so the refiners would only pay for 42 gallons.  I guess after they
figured out to put lids on the barrels, they just kept it at 42 gallons.

There are 6 barrels per "cube" (cubic meter) if you ever need to convert it.
Lisa Denke
Drilling and Completions Engineer