Large Scale TTI Imaging in Areas of Limited to No Well Control - Kwanza Basin Case Study

We present a case study from the Kwanza basin offshore Angola where we built a detailed tilted transversely isotropic (TTI) model over an area of more than 8000 km2. We incorporate general knowledge of the area and analysis of data anellipticity in the process, derive Thomsen’s δ in wells from a neighboring area and use spatially variable ε and δ fields, honoring the geometry of interpreted carbonate geo-body. The results are compared against images produced with both a much simpler regional TTI model and a legacy isotropic model. We demonstrate that, in spite of the lack of well control, high-quality TTI imaging is not only possible, but essential for producing geologically plausible and interpretable images in this complex area and that adding data- and interpretation-driven complexity in the TTI models could further improve the imaging of pre-salt targets.