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Using Geological Expression Techniques to Reveal Complex Regional Structural Information Without Conventional Interpretation

Tom Wooltorton
[email protected]

The workflows applied in the interpretation of regional structure in post-stack 3D seismic datasets evolved from techniques developed when 2D seismic first arose decades ago as a regional mapping tool. Nowadays, despite the high-resolution of 3D surveys and the availability of high-end processing machines, the techniques most commonly applied have not advanced significantly. Principally, structural interpretation of 3D seismic is achieved through the manual picking of faults on inlines and crosslines and then defining the geological context of the results. Occasionally this will be aided by seismic attributes or automated techniques. This can be inefficient for several reasons: firstly, manual interpretation is very time consuming. Secondly, there is a high risk of subjectivity. Work may also be rushed or details insufficiently examined. This paper discusses a fully-3D analysis of a dataset, using Geological Expression techniques, in order to determine what results can be obtained without manual picking. The goal of Geological Expression is to define distinct geological elements within the seismic, using data driven but interpreter guided processes to carry out analysis. The techniques include analysis of structural orientations within the data using volumetric dip and azimuth, extraction of different generations of faulting, and integration with knowledge of other exploration goals in the region. After illuminating the data in terms of separate geological domains, the analysis highlighted results that can be confidently interpreted as fault extension and reactivation through a regional capping lithology, which represents a notable seal failure risk. The use of volumetric techniques provided a basis for quantitative analysis to validate the ongoing interpretation.

AAPG Search and Discovery Article #90167©2013 GCAGS and GCSSEPM 63rd Annual Convention, New Orleans, Louisiana, October 6-8, 2013