Effects of a Partially Communicating Fault in a Composite Reservoir on Transient Pressure Testing

Summary Many reservoirs are faulted, and hydraulic characterization of these faults is essential for the design of field-scale developments. In addition to the effect that a fault has on fluid flow in the reservoir, it may separate two different reservoir regions with distinctly different properties. The detection of the properties on both sides of the fault and the distance to the fault are important in the reservoir-characterization process. In this study, a linear fault is modeled as an infinitesimal-thickness skin boundary. Analytical solutions for pressure-transient behavior for a line-source, constant-rate well in a composite reservoir are obtained with one Fourier space transformation and time-space Laplace transformations. The solutions are presented for strip and infinite reservoirs. This study examines drawdown-pressure and pressure-derivative behavior and extends and generalizes many studies presented in the past. Correlating parameters for pressure-transient responses are presented. The possibilities of boundary detections are considered, and interference pressure responses in a composite, strip reservoir are briefly discussed.