Estimating anisotropy parameters and traveltimes in the tau-p domain

摘要

The presence of anisotropy influences many aspects ofudseismic wave propagation and has therefore implicationsudfor conventional processing schemes. To estimate theudanisotropy, we need both forward modelling and inversionudtools. Exact forward modelling in anisotropic mediaudis generally done by raytracing. However, we present audnew and fast method, using the tau-p transform, to calculateudexact P and SV reflection moveout curves in stratified,udlaterally homogeneous, anisotropic media whichudrequires no ray tracing. Results are exact even if theudSV-waves display cusps. In addition, we show how theudsame method can be used for parameter estimation.udSince inversion for anisotropic parameters is veryudnonunique, we develop expressions requiring only a reducedudnumber of parameters. Nevertheless, predictionsudusing these expressions are more accurate than Taylorudseries expansions and are also able to handle cusps inudthe SV traveltime curves. In addition, layer stripping isuda linear process. Therefore, both effective (average) andudlocal (interval) estimates can be obtained.