This book covers all aspects of estimating and classifying reserves of crude oil, natural gas, and condensate attributed to primary recovery mechanisms. Both deterministic and probabilistic procedures are discussed. Reserves definitions for many of the major producing countries are provided, including a comparison of the US Securities and Exchange Commission and Society of Petroleum Engineers-World Petroleum Congress reserves definitions. Case histories illustrate reasons for errors in reserves estimation. Correlation charts and empirical equations to estimate pressure/volume/temperature properties of reservoir fluids are provided in one of several special appendices.