Resolving and Understanding Observed Azimuthal Anisotropy — A Case Study

This case study demonstrates that the regularization of single-sensor, single-source (S4) seismic data along discrete azimuth directions with regular source-detector distance intervals (radial domain gathers) can provide enhanced imaging through azimuthal velocity analysis, and deliver inversion-ready datasets with improved noise attenuation. A holistic workflow is presented that is tailored both to improve the final image quality, and to enable azimuthal amplitude variation with offset and azimuth (AVO/AVOAz) analyses, leading to the derivation of intrinsic rock property attributes leading to better reservoir management decisions & drilling plans. A prestack depth migration approach provides compensation for the overburden effect and improves resolution at the zone of interest by removing the effects of heterogeneities in the velocity field, which can be misinterpreted as azimuthal anisotropy.

The 2016 processing sequence of a dense, broadband 3D land seismic survey in Abu Dhabi supports the understanding that azimuth-rich S4 acquisition geometries can provide advantages over conventional techniques (such as the use of receiver arrays or narrow-azimuth surveys) for the imaging, fracture characterization, and reservoir management of very subtle low-relief structures, in particular shedding light on the complex geological environments of carbonate reservoirs in the Middle East.