Azimuthal Anisotropy Correction in Champion West 3D Survey - A Case Study

In this paper we present a case study describing the application of a correction for azimuthal velocity anisotropy on the Champion West 3D seismic survey, offshore Brunei. The survey consisted of conventional sail lines, plus regions of two-boat undershoot in the area of existing platforms. The undershooting resulted in very large azimuth variation, and irregular data coverage especially in near offset range. Coupled with the regional azimuthal velocity anisotropy, the large difference in trace azimuths caused time jitters in data, which in turn caused difficulty in imaging. In this study, an azimuthal differential NMO was applied to the data, after scanning for the anisotropy parameters on the basis of stack response. The correction made major improvement to the data, as seen both before and after migration. Before migration, jitters were moderated and stack response was better. After migration, the improvement was seen as better focusing and greatly reduced amplitude striping.