A barrel is one of several units of volume applied in various contexts. Tonne of oil equivalent should be used carefully when converting electrical units. In other commercial connections, barrel sizes such as beer keg volumes also are standardised in many countries. There is not a single conversion between mass and volume. It is used to tell amount of energy found in a barrel of crude oil. It’s very difficult for producers of genuine olive oil to get their product on the shelves. We all have our favorite cooking oils, but not everyone knows that they're not all interchangeable.
With respect,