The objective of this book is to provide a comprehensive understanding of the acquisition and processing of the basic data needed to evaluate and predict the behaviour of oil and gas reservoirs. The subjects covered are as follows: the physical properties of the reservoir rocks and the fluids they contain; the estimation of oil and gas reserves; the interpretation of well tests; the evaluation of producibility and of the distribution of reservoir fluids; the global behaviour of a reservoir and aquifer in contact. Each topic is dealt with in a concise and rigorous manner, and the underlying mathematics is presented in an easily comprehensible fashion.