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Successful Contributions of a Fit-for-Purpose Post-Stack Seismic Reprocessing for Proper Exploration/Appraisal Well Placement

Mahgoub, Mohamed *1; Hagiwara, Hiroshi 1; Obaid, Khalid 1; Al Mesaabi, Saif 1; Hussein, Thib 1
(1) Exploration, ADNOC, Abu Dhabi, United Arab Emirates.

With a condition that seismic data is a bit sparse in geometry and/or under sampling in general, the stat-of-the-art technologies or sophisticated processing techniques may not always help enough to have desirable/interpretable products no matter how much effort we put into the pre-stack processing. On the contrary, a fit-for-purpose post-stack processing could be an alternative which might resulted in seismic images with remarkable clarity, enabling geoscientists/engineers to locate wells in proper places.

Many 2D & 3D seismic surveys onshore and offshore Abu Dhabi have been subjected to the ADNOC in-house-fit-for-purpose post stack seismic reprocessing route. Their main objectives are to resolve the tuning effect, which is caused by different stratigraphic features, to enhance fault imaging at the targets levels and optimize the well placement ultimately. The input data often have some remnant issues, such as coherent/random noise, a variety of multiple and the limited bandwidth with relatively distorted to low frequency, does not usually help interpreters tracking target horizons even after imaging processing.

A fit-for-purpose post-stack seismic data processing route, which includes a sequence of 2D/3D FKK dip filter, notch filter, deconvolution after stack, spectral whitening and frequency slice filtering, has significantly contributed to the data quality enhancement at target levels of the data. Time-variant spectral whitening has amplified and whitened the effective frequency range without magnifying noise level or altering the phase/amplitude of the dataset. Deconvolution after stack enabled to reduce to fair extent of residual shallow water reverberations and remaining multiples on the datasets.

Our fit-for-purpose post-stack processing route, which has devised and demonstrated by ADNOC, readily reinforces excellences of seismic input seismic data from old vintage stacked seismic data for maximizing quality and stability of seismic interpretation, especially for the purpose of stable horizon mapping. Seismic attributes, such as curvature and coherency cubes, that have been extracted from the data after this processing, revealed subtle features such as fault lineaments, and eventually enabled the asset team to locate the well trajectory optimally.

 

AAPG Search and Discovery Article #90141©2012, GEO-2012, 10th Middle East Geosciences Conference and Exhibition, 4-7 March 2012, Manama, Bahrain