Abstract

An understanding of the geology of the area on a regional level helps us in deciphering the locations of the hydrocarbon source, migration of hydrocarbons from this source and their accumulation in the reservoir. Individual 3D seismic volumes give an idea of the geology locally, which is usually focused on imaging and improving the resolution of already discovered reservoirs. Also, the interpretations of 3D seismic data are reliable only in the full fold regions. If such a case occurs wherein some structure, not anticipated while planning of the survey, falls on the edge of the volume, it is not possible to reliably interpret. Also, carrying out a separate 3D for this would be a time-consuming matter. This defines the motivation of this case study. The authors in this case study, have taken up three nos. of individual 3D surveys, falling in Assam shelf part of OIL’s main producing area, and merged the datasets in the pre-stack domain in order to reliably image the overlapping low fold regions of the individual surveys. In this paper, the authors would like to draw attention to the advantages of pre-stack merging of existing overlapping 3D surveys in achieving a holistic understanding of the regional geology of the area. The authors would also like to point out the fallacies of the pre-stack merging which might result in decreased resolution of any survey used in the process which has higher resolution as compared to the final resolution of merged volume.