Salt diapirs without well defined boundaries – a feasibility study of semi-automatic detection
A. Berthelot, A.H.S. Solberg, E. Morisbak and L.J. Gelius
Journal name: Geophysical Prospecting
Issue: Vol 59, No 4, July 2011 pp. 682 - 696
Info: Article, PDF ( 1.58Mb )
Prestack depth imaging of seismic data in complex areas such as salt structures requires extensive velocity model updating. In many cases, salt boundaries can be difficult to identify due to lack of seismic reflectivity. Traditional amplitude based segmentation methods do not properly tackle this problem, resulting in extensive manual editing. This paper presents a selection of seismic attributes that can reveal texture differences between the salt diapirs and the surrounding geology as opposed to amplitude-sensitive attributes that are used in case of well defined boundaries. The approach consists of first extracting selected texture attributes, then using these attributes to train a classifier to estimate the probability that each pixel in the data set belongs to one of the following classes: near-horizontal layering, highly-dipping areas and the inside of the salt that appears more like a low amplitude area with small variations in texture. To find the border between the inside of the salt and the highly-dipping surroundings, the posterior probability of the class salt is input to a graph-cut algorithm that produces a smooth, continuous border. An in-line seismic section and a timeslice from a 3D North Sea data set were employed to test the proposed approach. Comparisons between the automatically segmented salt contours and the corresponding contours as provided by an experienced interpreter showed a high degree of similarity.