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Well-Driven Seismic Processing and Reservoir Characterization

By

 Stephen Patrick Morice1, Stefano Volterrani2, Tarek Nafie2, Ayman Shabrawi2

(1) WesternGeco, Gatwick Airport, United Kingdom (2) WesternGeco, Cairo, Egypt

 Our “Well-Driven” approach to surface-seismic processing integrates borehole data throughout the processing sequence to achieve accurate depth images with enhanced resolution, and constrained reservoir attributes from the seismic and well data.

Borehole data are used to guide pre- and post-stack seismic processing testing by quantifying the match between migrated test volumes and the synthetic seismogram or VSP corridor stack (e.g. Poggiagliolmi, 1998; Scott et al., 1999). Attributes based on the correlation between well data and the seismic data at the well location, and on characteristics of the extracted wavelet provide objective criteria for processing parameter selection.

Intrinsic processing parameters are derived from analysis of VSP and log data. An Earth model of P- and S-wave velocities, densities, attenuation and VTI anisotropy is built at the well location and extended over 2D or 3D. The model is used to drive offset-dependent attenuation compensation, geometric spreading corrections, demultiple operators, long-offset move-out corrections, ray-trace-based muting, travel-time tables for pre-stack depth migration and AVO analysis (Leaney et al., 2001).

Crucial to our method is appropriate conditioning of well data. Sonic and density curves are edited using a multi-well regression scheme through interactive, iterative calibration to VSP and surface-seismic data.

With the seismic data processing sequence optimized to the borehole data, we may proceed with greater confidence into seismic interpretation and the derivation of reservoir attributes through calibration and classification of seismic attributes with petrophysical and rock-physical borehole data. This paper describes our borehole-integrated processing and reservoir characterization methodology, showing examples from several recent projects.