Validating Remaining Oil Saturation from History Matched Simulation Model with Infill Wells in a Mature Oil Field

Remaining oil saturation prediction from the history matched simulation model is one of the main controls on production forecast. Validation of the remaining oil saturation from independent source would hence enhance confidence on the accuracy of the forecast. It would also provide valuable feedback on the robustness of the integrated reservoir modeling workflow. However, field-wide saturation measurements are uncommon. Infill wells and cased hole pulsed neutron logs can provide spot checks for the model but are local in nature. This paper presents a case study where field-wide remaining oil saturation estimates were available from extensive infill drilling during downsizing of an inverted 9 spot waterflood pattern to 5 spot polymer injection development. Comparison of well vs. model remaining oil saturation for two braided fluvial channel reservoirs are discussed, one with homogeneous sheet sand and second with significant heterogeneity. The results provide some key insights about fluid flow in braided channel reservoirs of varied heterogeneity. For the homogeneous sand, the wells matched the simulated waterfront movement and vertical saturation changes. In the heterogeneous sand, differences in the model to well saturation were seen, which highlighted need for better characterization of shale baffles and permeability heterogeneity in the static model.