Paper Summary
We present a case study of enhanced imaging of wideazimuth data from the Gulf of Mexico utilizing recent technologies; and we discuss the resulting improvements in image quality, especially in subsalt areas, relative to prior methodologies. The input seismic data set is taken from the large scale Freedom WAZ survey located in the Mississippi Canyon and Atwater Valley areas. In the course of developing the enhanced wide-azimuth processing flow, the following three key steps are found to have the most impact for improved subsalt imaging. 1) Data regularization to prepare the data for multiple attenuation as well as for the final run of anisotropic reverse time migration; 2) 3D true azimuth SRME to remove multiple energy, in particular, complex multiples beneath salt; 3) reverse time migration based delayed imaging time (DIT) scan to update the complex subsalt velocity model. The DIT scan further improves the accuracy of the subsalt velocity model after the conventional ray-based subsalt tomography. In this paper, we focus on the depth imaging aspects of the project, with particular emphasis on the application of the DIT scanning technique. We also demonstrate the uplift of acquiring a wide-azimuth data set relative to a standard narrowazimuth (NAZ) data set.
