Interpretation of Tests in Fissured and Multilayered Reservoirs With Double-Porosity Behavior: Theory and Practice

This paper summarizes current knowledge of reservoirs with double-porosity behavior. These include both naturally fissured reservoirs and multilayered reservoirs with high permeability contrast between layers. The first part presents available solutions to the direct problem (i.e., solutions to the diffusivity equation) that have appeared in the oil and ground water literature over the past 20 years. The second part discusses methods for solving the inverse problem--i.e., identifying a double-porosity behavior and evaluating all corresponding well and reservoir parameters. Several field examples demonstrate various aspects of double-porosity behavior and illustrate how additional knowledge of the reservoir (e.g., fissured vs. multilayered, gas saturation, etc.) can be obtained from numerical values of the reservoir parameters. Practical considerations for planning tests in double-porosity reservoirs also are included.