Seismic Probabilities and Multi-point Geostatistics - A Successful Solution to Model a Complex Depositional Environment

This paper describes the application of an advanced workflow for seismic driven reservoir characterization to an offshore field of West Africa in ultra-deep water environment. Probabilistic Petrophysical Seismic Inversion and Multiple-Point Simulation are the core of the workflow. These are successfully applied to model - at different scales - facies of complex architectural depositional elements, and the related petrophysical properties, moreover integrating data from different sources and relevant uncertainties. Geostatistical simulation of facies is based on a petro-elastic model of four classes defined at well scale, the same used in seismic inversion. Three geological models are created to mimic a thick Miocene turbidite sequence, one for each geological interval (Upper, Middle and Lower). The application achieved a satisfactory optimization and standardization of seismic integration workflow to generate geological/geophysical scenarios and provide a “tuned” reservoir description. The probabilistic approach also drove the technique used to select the reference cases (Low, Medium and High) for the dynamic model and the risk analysis. Finally the availability of multiple scenarios was useful to assess the impact of different geo-bodies occurrence on the reference development scheme. As result the geological uncertainty and the dynamic reservoir behaviour were fully addressed.