Three-Dimensional Modeling of Structurally Complex Reservoirs: The Revancha Field Case

Abstract In recent years, great effort has been devoted to the development of reservoir characterization techniques and the improvement of the geological description in the simulation model. As the geological complexity increases, the use of a conventional approach to represent the reservoir geometry becomes inappropriate. The goal of this work is to present a three-dimensional modeling analysis applied to a structurally complex reservoir. A field case is discussed to illustrate the approach while the integration among all reservoir management specialties is emphasized. This paper addresses the integrated reservoir study as part of the development plan for the Revancha field, in Colombia. This is a unique petroleum field located below the Andes Mountains. Its geological features are affected by the tectonic efforts typical of compressional basins. In fact, results from the three wells drilled so far show that there is a portion of the reservoir with nearly vertical bedding. This pattern brought great difficulty to its exploitation and, also, to its modeling. The targets of the study encompassed the evaluation of the field performance, the proposal of new wells to complement the reservoir drainage and the estimation of total reserves. It was clear, since the beginning of the analysis, that a conventional approach would not be appropriate for this kind of reservoir. Therefore, great effort was applied on the 3D geological modeling of the field using state-of-the-art tools, leading to its proper representation in the flow simulator. Using a generalized corner-point grid, the production history was matched and different production configuration schemes were tested. Since the target for increased production was the vertical portion of the reservoir, new 3D seismic data was acquired to further detail the new well locations, considering the greater uncertainty involved. Important conclusions are reached on how some of the tools available in the market can be used to model these complex reservoirs. In addition to the field data discussion and review, this paper focuses on the modeling challenges and the options chosen to overcome the difficulties.