Orthorhombic Migrations for Imaging Fractured Reservoirs

The combined effects of horizontal layering and vertical fracturing in the reservoir produce orthorhombic anisotropy. In order to properly image these kinds of reservoirs, we need to abandon the simple assumption of VTI and HTI as independent effects, used in current migration algorithms, and adopt new simultaneous accountings of both effects in the form of an orthorhombic time migration. In this paper we will describe the theoretical underpinning of orthorhombic symmetry, how we use it in migration and then show some results on real data. A discussion about the challenges associated with doing velocity updating will be briefly discussed at the end of the article