Long ago, engineers recognized the characteristic decline of oil and gas well performance and attempted to predict its course by fitting equations to the production history. This book covers the production characteristics and associated interpretation analyses of petroleum reservoirs in a complete, thorough, and consistent manner. Production decline-curve analyses are the most widely used tool in the industry for oil and gas reservoir production analyses. This book will serve as an authoritative reference on modern production decline-curve analyses, including details of some recent advances in the technology. Decline curves are probably the most widely used and least understood production-forecasting technique currently in use in the industry. Analysis of decline curves provides an unsophisticated reservoir-evaluation tool, but profound economic decisions often rest on the outcome of the prediction. A simplistic view of decline-curve analysis can lead to wide misuse, often caused by misunderstandings. There has been no single reference book on the meaning of production decline curves, their application, and their use and misuse. The authors have endeavored to provide such a reference.