The Society of Petroleum Engineers has posted its proposed 2007 petroleum reserves and resources classification, definitions and guidelines at its website for industry comment.

The primary updates are that the system is project-based; the class is based on the project's chance of commerciality; categorization is based on quantities recovered by applying a defined project to a reservoir base case that uses an evaluator's forecast of future conditions; and, the guidelines are applicable to unconventional resources, including oil sands and methane hydrates.

The draft definitions can be viewed at spe.org/reserves.