Initial model selection for efficient history matching of channel reservoirs using Ensemble Smoother

Moreover, it has been commented that ES is vulnerable to overshooting and filter divergence problem due to its global update. By selecting well-designed initial ensemble members, however, we can get better production forecasts using ES over EnKF while total simulation time is reduced about 93%. We confirm that the proposed method is effective even in the case with uncertain reservoir information and a field-scale model, PUNQ-S3. ES with the PCA-assisted model selection enables efficient history matching with a small number of ensemble realizations and one assimilation only.