RyVOL facilitates the preparation of volumetric reserves estimates for oil and gas wells and reservoirs. The menu-driven program provides templates for either oil or gas reservoirs and allows the user to determine such fluid and reservoir properties as gas deviation factors, pseudocritical temperatures and pressures, oil- and gas-formation volume factors and calculated solution gas-oil ratios. Volumetric in-place and recoverable reserves are based on user input for reservoir volumes and recovery factors. Secondary product recovery is calculated either as a percentage of product in-place or as a ratio relative to primary product. RyVOL works with the Reservoir Solutions Modules freeware program.