Chapter 3 – Pressure Transients and Crossflow Caused by Diffusivities in Multilayer Reservoirs

This section considers single-phase unsteady flow in a system of homogeneous layers separated by thin, low-permeability shales, and it has interlayer crossflow caused by different diffusivities for different layers. The model considers all layers are perforated that flows at a constant total rate. Numerical simulations of the problem for the semipermeable wall model are used to find the structure of the crossflows in typical cases. Analytical solutions for pressure and the n − 1 diffusivity crossflows are developed and compared with the numerical results. These solutions show how the diffusivity crossflows depend on layer properties and ordering. Their behavior and properties are discussed and their effects on pressure distributions are shown.