Introduction

The includes a discussion of the fundamental concepts that influence the displacement of oil and gas both by internal displacement processes and by external flooding processes. It is meant to be an introduction to these topics and not an exhaustive treatise. The reader, if interested, is referred to other works that cover the material.^1–5 The reservoir engineer should be exposed to these concepts because they form the basis for understanding secondary and tertiary flooding techniques, discussed in the next as well as some primary recovery mechanisms.