IMPROVED RESERVOIR CHARACTERIZATION AND SIMULATION OF A MATURE FIELD USING AN INTEGRATED APPROACH

Abstract

Reservoir characterization involves various studies which comprises assimilation and interpretation of representative reservoir rock and fluid data for a simulation model under varying recovery mechanisms. The main challenge in reservoir simulation is the task of simplifying complex reservoir situations while ensuring a high level of data utilization to obtain a unique solution for history matching. Retaining geologic continuity in the simulation model is necessary to ensure the predictive capability of the reservoir model. In this study, the systematic assignment of reservoir properties with optimal utilization of very limited data has ensured that the fluid movement through the heterogeneous reservoir rock in a mature field is appropriately established. The key towards such a systematic assignment is classification of pore attributes. Pore attributes, which occur due to variations in depositional environments and diagenetic processes in a reservoir, have been identified through interpretation of the petrophysical data and the development of core- well log relationships in a consistent manner. Electrofacies along with petrophysical classification methods have been applied to quantify heterogeneity found in carbonate and sandstone reservoirs. It is observed that the electrofacies derived from well logs represent lithofacies found in the core measurements. The characterization approach has been shown to provide reliable accuracy of petrophysical property prediction when comparison was made with core measurements. These optimum correlation models were extended to uncored wells to describe the reservoir simulation model. A reservoir simulation model, built using this approach, provides a rapid means for history matching between the simulated results and the observed productions at the field while retaining the geological continuity. The integrated approach and structured methodology developed in this study resulted in a reservoir simulation model with adequate resolution of data that simulated the production history with sufficient realism, without necessity for alternations in petrophysical properties.