Technical Paper: Large-scale TTI Imaging in Areas of Limited to No Well Control

Society: SBGF
Paper Number: 2647
Presentation Date: 2011


Depth imaging with anisotropic models has been shown to deliver more geologically plausible and accurate images. Derivation of accurate parameters describing anisotropic properties of the medium requires incorporating well information. However, there are vast exploration areas around the world with very limited to no well control that do require high-quality anisotropic imaging to allow adequate interpretation of deeper targets. We use a simple workflow that allows building of tilted transversely isotropic (TTI) models in areas of very limited well control. We present a case study from the Kwanza basin offshore Angola where we built a detailed TTI model over an area of more than 8000 km2. We incorporate general knowledge of the area and analysis of data anellepticity in the process, derive Thomsen’s δ in wells from a neighboring area, and use spatially variable ε and δ fields, honoring the variation of the anellipticity and the geometry of the provided horizon interpretation. The results are compared against images produced with both an isotropic model and a much simpler regional TTI model. The results illustrate that accounting for TTI in complex media is a prerequisite for producing geologically plausible and interpretable images, and that adding interpretation driven complexity in the TTI models could further improve the interpretability of pre-salt targets.

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