Title:Rapid Forecast and Optimization of Geological CO2 Storage in Deep Saline Aquifers: A Data-driven Dynamic Mode Decomposition Model Order Reduction Approach

Abstract:Data-driven and non-intrusive DMDc and DMDspc models successfully expedite the reconstruction and forecasting of CO2 fluid flow with acceptable accuracy margins, aiding in the rapid optimization of geological CO2 storage forecast and optimization. DMDc and DMDspc models were trained with weekly, monthly, and yearly simulation pressure and CO2 saturation fields using a commercial simulator. The domain of interest is a large-scale, offshore, highly heterogeneous reservoir model with over 100,000 cells. DMD snapshot reconstruction significantly reduced simulation times from several hours to mere minutes. DMDspc reduced the number of DMD modes for pressure without losing accuracy while sometimes even improving accuracy. Two operation cases were considered: 1. CO2 injection, 2. CO2 injection and water production for pressure maintenance. For pressure, DMDspc achieved a slightly higher than DMDc average error by removing several modes. On the other hand, DMDspc showed limited success in reducing modes for CO2 saturation. The forecast performance of DMD models was evaluated using percent change error, mean absolute error and Pearsons R correlation coefficient metrics. Almost all DMD pressure models managed to successfully forecast pressure fields, while a smaller number of DMD models managed to forecast CO2 saturation. While forecast errors have a considerable range, only DMD models with errors below 5% PCE for pressure or 0.01 MAE for saturation were considered acceptable for geological CO2 storage optimization. Optimized CO2 injection and water production amounts were consistent across selected DMD models and all time scales. The DMDspc-monitored cells approach, which only reconstructs the monitored-during-optimization cells, reduced even further optimization time while providing consistent results with the optimization that used full snapshot reconstruction.