Simulation of a Complex Fluvial-Deltaic Reservoir to Identify Opportunities to Improve Oil Recovery in a Mature Oil Field: A Case History

Abstract

A meandering system where sandbodies produced are complex, so that fluvial deltaic reservoir consist of channel belt sandbodies with highly variable permeability patterns pose a significant challenge for further development of a mature oil field in the Southwest Venezuela. To obtain an optimal strategy a multi-disciplinary reservoir characterization study was carried out. This study combined all available data (geophysics, geology, petrophysics, and engineering) into a 3D stochastic geo-model to build a reservoir simulation model, many sensitivities with grid size and reservoir description in fluvially dominated deltaic facies were undertaken. These sensitivities included various assumptions on sand content of main producing horizons, sandbody dimensions, permeability distribution, and continuity of flood plain acting as vertical barriers in some reservoir areas. All these sensitivities were tested during history matching as alternatives to reach a history match. Drilling locations and some exploitation strategies were made in order to improve the oil recovery factor through closing some wells for several periods (3 months - 6 months) and then opening those wells, this technique helped to decrease the water production rate and increased slightly the oil production rate. The associated economic evaluations were based on simulated forecasts while connected volume calculation was made for the chosen realization.