MIGRATION-BASED ILLUMINATION DETERMINATION FOR AVA RISK ASSESSMENT.

摘要

According to a preferred aspect of the instant invention, there is provided herein a system and method for extending zero-offset or stacked wave-equation illumination analysis into the angle-gather domain, where it becomes an appropriate tool for assessing the effects of complex overburden on AVA response. A preferred method for doing this involves first creating an angle gather that has a perfect AVA response (i.e. a constant amplitude as a function of angle). This gather is then preferably used as a reflectivity map that is fed into a demigration process which creates modeled data that by construction carries with it a completely flat reflectivity signature. Remigration of such a data set then results in a gather on which any amplitude variation is more likely to be a measure of illumination effects alone. The resulting AVA signature on the gather can then be used to assess the validity of the AVA response on modeled or actual data, resulting in a useful AVA risk analysis.