Over the last decade, professionals in the various reservoir disciplines (geology, geophysics, petrophysics and reservoir engineering) have learned to work together and strive for synergy. They have created multidisciplinary teams and organized common working environments where they compile integrated databases, design interoperable applications, and share earth models. This integration process generates extra value. When applied to reservoir studies, it can help foster more effective, less expensive projects. What, however, does integration really mean, under everyday working conditionsoe Which new technical and professional challenges must be facedoe What kind of changes does it imply for traditional ways of workingoe What is the role of the project leader in this processoe The goal of this book is to provide answers to these questions, and to highlight the critical differences between an integrated reservoir study and a traditional one. In his foreword, J.C. Sabathier writes: "To every professional, I recommend without hesitation to keep this precious manual at hand, as a reference for those decisions that are outside their domain of excellence. I only regret I had to wait until the year 2001 to encounter such a manual."