APPLICATIONS OF 3D SEISMIC VOLUME ATTRIBUTE ANALYSIS TO MAPPING FACIES IN DEPOSITIONAL SYSTEMS TRACTS
DAVID J. HALL, BRUCE E. BOWEN, 1996. "APPLICATIONS OF 3D SEISMIC VOLUME ATTRIBUTE ANALYSIS TO MAPPING FACIES IN DEPOSITIONAL SYSTEMS TRACTS", Stratigraphic Analysis Utilizing Advanced Geophysical, Wireline and Borehole Technology for Petroleum Exploration and Production, Jory A. Pacht, Robert E. Sheriff, Bob F. Perkins
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The widespread availability of high-quality 3D seismic surveys covering large areas has made the sequence stratigraphic analysis of lithofacies variations within these data sets both practical and of critical importance for exploration and production alike. We have found that volume seismic attribute analysis (including integrated reflection intensity, reflection heterogeneity, and reflection strength), calibrated to local conditions in wells which have penetrated the relevant strata, is a particularly valuable tool for mapping depositional facies patterns. The technique involves careful manual interpretation and editing of selected horizons along a dense grid of seismic lines and time slices. Horizons are chosen with full regard to the regional sequence stratigraphic context (from 2D seismic, regional 3D, and biostratigraphically documented well control). Unless the data set has extremely high S/N and is largely unfaulted, loop auto-tracking is not usually adequate for stratigraphic purposes. Frequent use of aids such as horizon flattening, various color displays designed to emphasize continuity, “zoom” and “unzoom,” composite sections tying wells, seismic correlation, and multi-frame windows helps to resolve questionable areas and establish internal consistency. Once a carefully edited, consistent, and geometrically correct interpretation has been achieved, meaningful volume attribute maps of systems tracts may be constructed. From the large number of attributes which can be calculated, usually a small number in a given sequence stratigraphic context will show the best correlation with known lithofacies and be most useful. These can be selected by extrapolation from known stratigraphic units in wells. We have found this procedure to be far more reliable than theoretical inference based on models of limited and generally unknown applicability. Facies attributions (alluvial, fluvial/coastal plain, lacustrine, near-shore marine, neritic, and slope environments) are supported by the attribute analysis. Sand-prone and source rock facies are identifiable, systems tract by systems tract. We believe volume attribute analysis has widespread general applicability and can be developed and utilized to solve a number of outstanding exploration and production problems.