Book excerpt: Well Test Analysis for Multilayered Reservoirs with Formation Crossflow introduces the fundamentals of well test analysis of a multilayered reservoir with formation crossflow. The effects of reservoir parameters on wellbore pressure and flow rate are examined, as is a proper method that has been established to analyze well test data that leads to better determinations on the reservoir parameters for each layer of the reservoir. Focusing on multilayer models for data analysis, this reference explains the reasons for the existence of single-phase crossflow in multilayer reservoirs, exploring methods to establish them and presenting practical applications to utilize and implement for today's more complex reservoirs. Aiding in better well testing operations and models, this book is a one-stop solution for today's reservoir and production engineer, helping them understand every layer of their reservoir. - Includes real-world examples of well testing through multilayered reservoirs, whether with crossflow or with formation crossflow - Provides strong guidance and criteria of research on reservoir dynamic performance, such as physical models and mathematical models - Includes a new unsteady crossflow model for vertical interference testing in low-permeability zones - Describes interpretation methods for different cases in multilayer reservoirs, including a new model called semipermeable walls for stratified reservoirs, drawdown test procedures and layer-by-layer test procedures that are useful for shales between layers