North Sea Field Application of 4D Bayesian Inversion to Pressure and Saturation Changes

In this work we present a workflow for 4D seismic inversion to pressure and saturation changes that uses a full petro-elastic and convolution forward seismic modelling operator and a Bayesian formulation for combining information from a history matched simulation model and seismic data. The forward modelling operator is ideal for capturing the non-linearities due to gas saturation and pressure changes. The inversion method is applied to maps of Schiehallion field in the North Sea, to invert seismic 4D AVO attributes into changes in pressure, water and gas saturations. The results can be interpreted as an updated view of reservoir dynamics, bringing together information from seismic data and the current history matched reservoir simulation results. In the presented application to the Schiehallion field, the inversion results offered important insights into overlooked pressurized compartments, updated water fronts and the global distribution of the released gas.