Six years ago, at the end of my professional career in the oil industry, I left my management position within Agip S.p.A., a major multinational oil company whose headquarters are in Italy, to take up the chair in reservoir engineering at the University of Bologna, Italy. There, I decided to prepare what was initially intended to be a set of lecture notes for the students attending the course. However, while preparing these notes, I became so absorbed in the subject matter that I soon found myself creating a substantial volume of text which could not only serve as a university course material, but also as a reference for wider professional applications. Thanks to the interest shown by the then president of Agip, Ing. Giuseppe Muscarella, this did indeed culminate in the publication of the first Italian edition of this book in 1989. The translation into English and publication of these volumes owes much to the encouragement of the current president of Agip, Ing. Guglielmo Moscato. My grateful thanks are due to both gentlemen. And now - the English version, translated from the second Italian edition, and containing a number of revisions and much additional material. As well as providing a solid theoretical basis for the various topics, this work draws extensively on my 36 years of worldwide experience in the development and exploitation of oil and gas fields.