Book excerpt: Reserves Estimation for Geopressured Gas Reservoirs aims to introduce the principles and methods for calculating reserves of geopressured gas reservoirs with the material balance method, presenting advantages, disadvantages and applicable conditions of various methods. The book, based on manual analysis, explains methods and calculation steps with more than 30 gas reservoir examples. It will help gas reservoir engineers learn basic principles and calculation methods and familiarize themselves with the content of the software Black Box, which in turn helps improve the level of gas field performance analysis and the level of gas field development. - Introduces 22 methods, such as the Hammerlindl method (1971), Ramagost-Farshad method (1981), Roach method (1981), Poston-Chen-Akhtar method (1994), Hedong Sun method (2019, 2020, 2021), et al - Offers "one-stop shopping" for the gas reservoir engineer on reserve estimation for geopressured gas reservoirs, including mathematical models, analyzing processes, analysis examples, and pros and cons - Suitable for the beginner, intermediate and advanced user who has a background in reservoir engineering - Provides a large number of examples about HPHT gas reservoirs - Reflects the combination, promotion and redevelopment of the gas reservoir engineering theory and field practice