ROCKMAN wrote:A minor correction: 1 barrel = 42 gallons.
And for bonus points: why is it "bbl" and not "bl"?
Wikipedia to the rescue...
https://en.wikipedia.org/wiki/Barrel_(unit)#Definitions_and_units
The abbreviations Mbbl and MMbbl refer to one thousand and one million barrels, respectively. These are derived from the Latin "mille" meaning "thousand". This is different from the SI convention where "M" stands for the Greek "mega", meaning "million". Outside of the oil industry, the unit Mbbl (megabarrel) can sometimes stand for one million barrels. The "b" may have been doubled originally to indicate the plural (1 bl, 2 bbl), or possibly it was doubled to eliminate any confusion with bl as a symbol for the bale.