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ABSTRACT: 3-D image processing techniques applied to carbonate reservoirs

Masaferro, Jose L.1, Ruth Bourne1, Tony Cortis1 (1) Shell International Exploration and Production B.V, Rijswijk, Netherlands

Conventional 3-D seismic mapping is not an ideal predictive method when attempting to characterise carbonate reservoirs due mainly to the complexity and heterogeneity of carbonate systems. In carbonates, the combined effect of variations in depositional facies and diagenetic alterations control variations in sonic velocities and thus in acoustic impedance. The definition of seismic facies are then controlled by acoustic impedance contrast which may be rather poor in various carbonates environments (i.e. shallow-water platform carbonates). Accurate 3-D imaging of seismic facies and geometries is critical to construct a realistic, seismically constrained reservoir model

We have applied various 3-D image processing techniques to produce filtered seismic reflectivity data ("Shell optimum filters") and volume attributes to better visualise and delineate seismic facies and geometries of heterogeneous carbonate reservoirs. Image filtering techniques were applied to improve signal-to-noise ratios and to suppress random noise to obtain a better reflection definition. Combined volume dip and azimuth was calculated from the seismic cubes to detect subtle stratigraphic features such as low-angle progradation units and shoal-type mounded seismic facies. Semblance volumes were used to highlight reflection terminations and helped to distinguish between stratigraphic and structural features. In addition, automated classification techniques were applied to the 3-D attribute-generated volumes to extract potential good reservoir zones.

Seismic facies and geometries interpreted from the attribute analyses, combined with interpretation of the original seismic and core/log data, allowed us to construct detailed depositional models that were used as input for static reservoir models.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia