Rate Transient Analysis in Two-Layered Reservoir Without Crossflow

Abstract

Analysis of modern production data also known as Rate Transient Analysis (RTA) is a technique to perform reservoir characterization using the combination of bottomhole flowing pressure and flow rate data without the need to close wells. These methods allow the estimation of the Hydrocarbon Initially In-Place (HIIP), production forecast and main reservoir parameters. Several RTA methods have already been developed to analyze different reservoir models such as homogeneous, naturally fractured, geopressurized, hydraulically fractured, however, in the case of layered reservoirs the studies are almost null although there are several studies conducted in the area of pressure transient analysis. This paper presents the analytical derivation of the Palacio-Blasingame type curves to analyze production data of a two-layered reservoir model without crossflow or hydraulic communication between them. A new set of type curves were generated by applying the Gaver Stehfest algorithm with Matlab to achieve the solution of the inverse of the Laplace space considering a constant flow of production flow and a flow regime in the radial pseudosteady-state, then applying the definitions dimensionless the proposed method was derived. Synthetic data were generated with a commercial simulator to validate the method. Furthermore this paper presents a field case study application. The results were compared to the type curve for homogenous reservoirs, volumetric method as well as well testing results. Results confirmed the applicability of rate transient analysis technique in a two-layered reservoir without crossflow with a single drainage area and the same initial pressure for all layers (same pressure gradient of formation), and different values of thickness of the layers, permeability and porosity.