Short answers, pulled from the story.
The 2018 petroleum resources management system provides a consistent approach to estimating quantities within a comprehensive framework. This system was jointly developed by the Society of Petroleum Engineers, the World Petroleum Council, and several other geological societies.
Proven reserves are discovered volumes claimed to have reasonable certainty of being recoverable under existing economic conditions. Industry specialists refer to this category as P90, meaning there is a 90% certainty of producing that volume.
Companies listed on U.S. stock exchanges could verify their claims confidentially until January 2010 when rules changed. Since then, the SEC allows companies to provide additional optional information declaring 2P and 3P estimates.
Three main categories of technique determine resource estimation based on maturity levels including analog methods, volumetric calculations, and performance-based methods. Analog methods involve identifying areas containing producing assets that are geologically similar to those being estimated while volumetric calculations use equations involving gross rock volume, porosity, and saturation factors.
Reserve growth refers to the typical increase in estimated volume where initial estimates of newly discovered oil fields are usually too low. As years pass, successive estimates of ultimate recovery tend to increase over time because more data becomes available during development.