A transversely isotropic medium with a tilted symmetry axis normal to the reflector
KAUST DepartmentPhysical Sciences and Engineering (PSE) Division
Environmental Science and Engineering Program
Earth Science and Engineering Program
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AbstractThe computational tools for imaging in transversely isotropic media with tilted axes of symmetry (TTI) are complex and in most cases do not have an explicit closed-form representation. Developing such tools for a TTI medium with tilt constrained to be normal to the reflector dip (DTI) reduces their complexity and allows for closed-form representations. The homogeneous-case zero-offset migration in such a medium can be performed using an isotropic operator scaled by the velocity of the medium in the tilt direction. For the nonzero-offset case, the reflection angle is always equal to the incidence angle, and thus, the velocities for the source and receiver waves at the reflection point are equal and explicitly dependent on the reflection angle. This fact allows for the development of explicit representations for angle decomposition as well as moveout formulas for analysis of extended images obtained by wave-equation migration. Although setting the tilt normal to the reflector dip may not be valid everywhere (i.e., on salt flanks), it can be used in the process of velocity model building, in which such constrains are useful and typically are used. © 2010 Society of Exploration Geophysicists.
SponsorsWe are grateful to KAUST and to the sponsors of the Center for Wave Phenomena at Colorado School of Mines for their support. We thank the associate editor and the reviewers for their critical review of this paper.
PublisherSociety of Exploration Geophysicists