A Practical Approach in Building Upscaled Simulation Model for a Large Middle East Carbonate Reservoir Having Long Production History

Abstract

Abstract A comprehensive reservoir model that provides excellent turnaround time for historymatch and evaluation of different development scenarios had been developed through careful application of upscaling methods for the large carbonate reservoir of Umm Gudair field located inKuwait and partitionedneutral zone. The model was built maintaining integrity of the geological model. The detailed geologic model, built using the latest techniques, was very large (157 layers, 10 million cells) and itwas necessary to upscale the model into a reasonably sized simulation model thatruns smoothly witha good turnaround timetomakemultiple runs tomatch 42 years oil/water productionand pressure history ofabout 200 wells. The vertical upscaling were to bedone maintaining the integrity of the fine-scale geological model, preserving physics of the displacement process and providing provisions for water shut off jobs implemented through squeezing off bottom perforations. Although the flux-basedupscaling techniques provided guidance, it alone was not sufficient to optimize the layering scheme for the simulation model. A hybrid approach combining the elements of the methods of minimizing variation and flux, manual judgment and streamline simulation was applied to generate a vertically upscaled model with 42 layers that effectively replicated the fine-scale fluid flow behavior. Two simulation modelswere generatedwith different arealdimensions - a coarse modelwith 200×200 mt (to accelerate the history match process) and a fine-scale model with 100×100 mt (983,000 active cells) for infill drilling studies. Excellent history match has been achievedand the model has been demonstrated as an effective reservoir management tool for further field development. This paper discusses the steps applied towards effectively converting the geologic model to simulation model through upscaling, the systematic approach towards buildingthe history match model highlighting the critical steps and an overview of the quality ofhistory match.