Imaging Techniques for Minor Faults: A Workflow for Running Coherency Attributes

Dipankar Manna and Arunkumar Arya
GEOPIC, ONGC, Dehradun, India

This study provides a method for better mapping of minor faults in a 3D seismic dataset. Besides conventional attributes like spectral decomposition, coherency attributes which are used for minor fault mapping, a workflow is designed for running coherency attribute which gives better clarity in mapping minor faults through coherency time slices. A 3D land dataset pertaining to Charali-Changmaigaon area of North Assam shelf of Assam-Arakan Basin of India is used. The target reservoir is Tipam sand which is subdivided into blocks by NNE-SSW major faults and the NW-SE cross faults. The minor faults which are associated with these major faults are responsible for compartmentalization of Tipam reservoir. These minor faults are difficult to be mapped by conventional interpretation tools. Spectral decomposition and coherency attribute which are generally reported for minor fault detection are also used. Spectral decomposition produced better image for minor faults in comparison with coherency attribute drawn from inversion volume and normal amplitude volume. But coherency attributes run on noise processed instantaneous/cosine phase data produced the best results.

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