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Shear-wave Splitting and Azimuthal Anisotropy in an Offshore Field in the Arabian GulfNormal access

Authors: J.P. Holden, B. Beck, M.J. Grimshaw, C. Giersz and F. Al-Enazi
Event name: 76th EAGE Conference and Exhibition 2014
Session: Multi-component Case Studies
Publication date: 16 June 2014
DOI: 10.3997/2214-4609.20140642
Organisations: EAGE
Language: English
Info: Extended abstract, PDF ( 3.24Mb )
Price: € 20

The effect of shear-wave splitting, an expression of an azimuthal anisotropic medium, has been observed in shear-wave seismic reflection recordings since at least the 1980’s. Since those early experiments it has been recognised that the existence of this phenomenon will degrade shear-wave images unless the issue is addressed adequately within data processing. A 4-component converted-wave dataset acquired in the Arabian Gulf exhibits such shear-wave splitting. Significant azimuthal anisotropy within the overburden, and locally in excess of 10%, results in a severe loss of coherency on the radial component. Correcting for the shear-wave splitting in this and subsequent intervals dramatically improves both the vertical and spatial resolution, and therefore the interpretability, of the data. The resulting attributes from the analyses also yield information on the evolution of the subsurface. Of particular note is the overprinting of the azimuthal anisotropy in the post-Eocene overburden by the pre-Turonian (Cretaceous) faulted anticline. This is consistent with an interpretation of late uplift of this deep structure and the consequent extension of the overburden in a direction orthogonal to the structural axis.

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