Seismic Reservoir Characterisation using Seismic Inversion: A Case Study Showing Importance of Prior Model

Summary Deep water fields with turbidite depositional systems have been successfully characterised based on deterministic inversion. We describe a case study on seismic reservoir characterization using seismic inversion outputs on a deep-water gas field, offshore Mozambique and highlight the importance of a well-defined prior model to achieve good inversion results. The field is composed of deep-water turbidite reservoirs with thick (up to 100m) homogeneous sand intervals characterised by structurally complex toe-thrust and associated faulting to the west, and more stratigraphic and lithology complexities in the east. Therefore, a successful inversion process is one that can capture the structural and stratigraphic complexities in the results. The prior model is essential to aid seismic inversion give useful output. Therefore, the prior model was carefully built to capture the identified complexities and guide the inversion process. This was pivotal to constraining the inversion especially, in the toe-thrust affected region. Inversion results obtained reflected the field complexities and had good correlation with elastic logs from well data. Pseudo volume of clay and porosity datasets were computed based on the inversion results to help reservoir characterization and used for detailed fairway interpretation and geomodel construction.