Vertical Aggregation of Reservoir Simulation Models for Numerical Well Testing

Upscaling reservoir simulation models in an appropriate manner is important for any well test interpretation workflow which involves numerical reservoir simulation. Approaches based on steady-state flow behaviour are not necessarily optimal when trying to capture the details of pressure transient phenomena. This study proposes a new layer aggregation strategy which forms a weighted sum of the permeability differences between cells in neighbouring layers. The weighting uses a kernel function (G) presented by Oliver (1990). This approach was successfully applied in four upscaling experiments using a permeability distribution based on the Tarbert formation. These cases included a standard well test, an interference test and a test from a partially penetrating well. The results showed that coarsened models with as few as five layers can reproduce the pressure transient behaviour of a twenty layer fine grid model.