1. Anisotropic Prestack Depth Imaging Onshore Libya
Anisotropic Prestack Depth Imaging Onshore Libya
Christian Hanitzsch1, Bas van der Es1, Malcolm King2, Phil Whitfield3, Tamara Khlussovich3
1 Wintershall-Libya, Tripoli, Libya;
Mail address: PO Box , Kassel, Germany
2 Monarch Technical Services, UK
3 WesternGeco UK

2. Summary: Negative anisotropy
PreSDM: Negative anisotropy (VTI, d<0; e<0) is required to tie the seismic to well marker depths and maintain focused gathers. This is unusual.
Walkaway: Traveltime inversion shows negative anisotropy.
Core analysis: 8 of 12 samples indicate negative anisotropy. However, there are scale differences.
Three independent measurements confirm the presence of negative anisotropy for 2000 m thick limestones in this area (east Sirte basin).
EAGE: Anisotropic Prestack Depth Imaging Onshore Libya
3 June 2003

3. EAGE: Anisotropic Prestack Depth Imaging Onshore Libya
Conclusions
Significantly improved image quality from PreSDM, compared to poststack and prestack time migration.
Major impact on interpretation of Top Reservoir
Better focus of overburden provides a better integrated fault interpretation
Anisotropy minimized risk for future well positioning
Negative anisotropy for 2000 m thick interval of mainly limestones, confirmed by walkaway and core analysis
EAGE: Anisotropic Prestack Depth Imaging Onshore Libya
3 June 2003