Added Value of Using a 3D Faulted a Priori Model with Seismic Inversion - A Real Case Study of the Alwyn North Field

Usually stratigraphic inversion is performed using an a priori model built without taking into account a 3D fault network. The model is then filled by extrapolating physical attributes from well logs, following a given mode of deposition within each geological unit of the geometrical framework. The aim of this work is to evaluate the added value of stratigraphic inversion using a 3D faulted a priori model. We brought into focus a three-step workflow to build a 3D faulted a priori model, using only the original 3D fault geometry and interpreted seismic horizons. The resulting workflow output is a complete series of cubes filled up by several kinds of mandatory properties, not only geometrical like Azimuth, Dip of stratification, geological unit labels, but also physical attributes like elastic Impedances. To achieve our goal, we considered the faulted and no-faulted a priori model to perform stratigraphic inversions of the Alwyn North Field case study (UK North Sea). Then we compared both inverted acoustic impedance overlaying the Top-Brent horizon with the initial interpreted fault network. The inversion results obtained with a faulted a priori model are enhanced in the faulted area.