Gene Whitney (Section Research Manager at the Congressional Research Service), Carl E. Behrens (Specialist in Energy Policy at the CRS) and Carol Glover (Information Research Specialist at the CRS) November 2010 “U.S. Fossil Fuel Resources:
Terminology, Reporting, and Summary” http://epw.senate.gov/public/index.cfm?FuseAction=Files.view&FileStore_id=04212e22-c1b3-41f2-b0ba-0da5eaead952
Terminology A search for energy statistics in the literature quickly reveals a large number of terms used to describe amounts of fossil fuels. Most of these terms have precise and legitimate definitions, and even a careful comparison of statistics for diverse forms of fossil fuels can become quite difficult to reconcile or understand. Not only do oil, natural gas, and coal occur in many diverse geologic environments, but each commodity may occur in different modes or in different geologic settings that impose vastly different economics on their recovery and delivery to market. A vocabulary of terms has developed over the decades to capture the nature of deposits in terms of their likelihood of being developed and their stage of development.