Analysis of the seismic coherence attribute with respect to subsurface fault geometry

The objective of this study was to analyze the behavior of the seismic coherence attribute, particularly its relationship to subsurface fault geometry. Using data from the seismic survey of the Kuparuk River Field of the North Slope of Alaska as well as model data, a Monte Carlo method was applied to test the sensitivity of the coherence attribute in both settings. In the model setting the study tested coherence response to single faults, fault intersections, and master-minor fault geometries. The number of statistical experiments conducted for the Monte Carlo technique was restricted due to significant College of Engineering; times required to generate coherence volumes. The study concluded that the coherence attribute responds differently to different fault geometries. The ability of this attribute to resolve fault geometry depends on the selection of input parameters within the software suite used to compute it and on the frequency of sampling performed on the resulting coherence volumes. It was confirmed that the coherence attribute is affected significantly by the choice of migration methodology. Random noise of up to 50% of the absolute value of the maximum amplitude, on the other hand, has a negligible effect on how faults are imaged with the coherence attribute. Analyzing a composite result of several statistical coherence extractions is an improvement over mapping a single coherence volume on an interpreted fault surface. This study related a geophysical attribute to a geologic property, a relationship that can be used for detailed interpretations of fault geometry from coherence attribute volumes in the future.