A large portion of resources will never be produced, requiring more energy to produce than can be recovered. Each one uses its own version of the definition for its own purposes. Forecasting no oil shock is safer, whereas if one happens, it will be declared a natural unpredictable catastrophe. Saudi Arabia is an explosive country, and any political change can trigger a new oil crisis.
Conclusions Reporting reserves is a political act.
Information on the size of petroleum assets is poor, because of confidentiality and lack of consensus. Most official agencies, relying on unreliable published data , forecast that there is no problem of supplying the future demand for the next 20 years without a major petroleum price increase. An erroneous methodology is used in the USA for reporting proven reserves because of SEC rules. Reserves are constantly revised, as neglected probable becomes proven. Using the expected values method removes the illusion of field growth.