Patent ID: 7663972

Claim:
A method for estimating seismic velocities in vertically transversely isotropic media, comprising: generating an initial estimate of vertical interval velocity and interval normal moveout velocity with respect to depth from seismic data acquired by actuating a seismic energy source at a plurality of positions above subsurface formations to be evaluated and detecting reflected seismic energy at a plurality of seismic receivers disposed above the formations; generating an initial estimate of a first anisotropy parameter with respect to depth, the first anisotropy parameter related to the interval normal moveout velocity and the interval vertical velocity; generating an initial estimate with respect to depth of a second anisotropy parameter, the second anisotropy parameter related to the first anisotropy parameter and an interval anelliptic parameter; performing on a processor a first tomographic inversion with respect to the interval normal moveout velocity and the second anisotropy parameter at a constant value of the first anisotropy parameter until travel time differentials reach minimum values; first adjusting layer depths on a processor with the initial estimate of vertical interval velocity and interval normal moveout velocity with respect to depth from seismic data; using values of the second anisotropy parameter determined in the first tomographic inversion, performing on a processor a second tomographic inversion of interval normal moveout velocity and the first anisotropy parameter with respect to depth; second adjusting on a processor the first adjusted layer depths, interval normal moveout velocities and interval vertical velocities and calculating interval anelliptic parameters from the second tomographic inversion; and at least one of storing and displaying the second adjusted layer depths, interval normal moveout velocities and calculated interval anelliptic parameters.