B/D 4 : Symbol for barrels of oil per day (see barrel [2] above), a unit used in the energy industry to measure the rate at which oil is pumped from a well
Russ Rowlett (Director), How Many? A Dictionary of Units of Measurement, Center for Mathematics and Science Education University of North Carolina, USA 2005. http://www.unc.edu/~rowlett/units/dictA.html, (Unit of Meas and Covr Factors - Amer) {608}