SEC is asking oil & gas companies to disclose how much of their “reserves” are oil, versus less valuable substances like natural gas liquids. Is 6% material? Wall Street Journal, September 14, 2013 http://on.wsj.com/18nhBZ1
Some of this goes to data quality – do the words mean what you think they mean? Some goes to regulation. And if you have this breakdown internally, why wouldn’t you want your shareholders to know? Do some people have reserves with a much higher proportion of non-crude liquids?