Wave Equation versus Kirchhoff pre-stack depth migration algorithms ? An Australian case study

Abstract

Oil companies demand for depth imaging technologies to be applied as part of their data processing sequence is quickly growing. Amongst depth imaging technologies, also rapidly evolving, are the ways seismic data are pre-stack depth migrated once a reliable depth model is available. Until a few years ago Kirchhoff type algorithms have been widely used to perform pre stack depth migration (PSDM). Although making approximations on the imaged data, they are economical, reliable, and easy to implement and understand. Advances in computing however, have now made the long known Wave equation type algorithms an economically feasible alternative for pre stack depth migration as they have shown advantages over the Kirchhoff type particularly under the salt structures of the Gulf of Mexico. Rare are the opportunities, however, to encounter salt structures such as the ones seen in the Gulf of Mexico on Australian datasets. Still Wave equation algorithms have theoretical advantages over Kirchhoff that we review in the first part of the article. In order to determine if those theoretical advantages improve the imaging of the structures seen around Australia, it is on the Australian dataset of the Skua and Swift fields in the Bonaparte basin, where both Kirchhoff and Wave equation pre stack depth imaging were performed, that we analyse and compare the two methods. We show that superior continuity, imaging and resolution of the seismic reflectors are obtained using the Wave equation algorithm.