Transient Pressure Response of Fluvial Reservoir With Branching Channel and Splay

Abstract

Abstract Fluvial reservoirs with branching channels and splays comprise a commonly encountered depositional system, however, characterization of this type of system using transient pressure analysis has not yet been fully explored. This article presents a semi-analytical method to compute the transient pressure and pressure response for this system type. It simplifies the computation by decoupling the complex-geometry system into a discrete set of simple-geometry systems that are in hydraulic contact with each other, and exchange fluids at their hydraulic contacts[1,2]. The computed pressure and pressure derivatives were compared with those of other simple well/reservoir systems to gain insight into the information contained in the responses. The source and sink method[3] was used to compute the pressure response in the Laplace domain and the results were inverted numerically using the Stehfest Inversion algorithm[4]. The discussion in this paper is focused on four cases, consisting of a main channel and a side branch that connects with the main branch at angles of 30, 45, 60 and 90 degrees, respectively. In each of these cases, the set of "image" wells that create no-flow boundaries is easy to generate, and an efficient computational algorithm is developed. Excellent pressure and pressure derivative responses have been obtained; detailed examination of these responses provides insight into methods that may aid in the identification and characterization of this type of system.