Application of super-virtual seismic refraction interferometry C omplex near-surface anomalies are one of the main onshore challenges facing seismic data processors. Refraction tomography is becoming a common technology to estimate an accurate near-surface velocity model. This process involves picking the first arrivals of refracted waves. One of the main challenges with refraction tomography is the low signalto-noise ratio characterizing the first-break waveform arrivals, especially for the far-offset receivers. This is especially evident in data recorded using reflection acquisition geometry. This low signal-to-noise ratio is caused by signal attenuation due to geometrical spreading of the seismic wavefield, near-surfacegenerated noise, and amplitude absorption. Super-virtual refraction interferometry improves the quality of the first-break picks by enhancing the amplitude of the refracted waves and attenuating the amplitude of the random noise.The theory of refraction interferometry was developed by Dong et al. (2006) related traces over all postcritical source positions yields a trace with a virtual refraction event that has an enhanced signal-tonoise ratio. This enhancement can be as high as , where N is the number of sources that contribute to the generation of this particular virtual head wave. They demonstrate this method on land data shot over a salt dome in Utah and later Nichols et al. (2010) showed its effectiveness in a hydrogeophysical research site in Idaho.A problem with refraction interferometry is that, if only the head wave arrivals are correlated with one another, the virtual head-wave trace has the correct moveout pattern. It has an unknown excitation time, so as a remedy, Dong et al. suggested that the source be "virtually" relocated to the surface by calibrating the virtual stacked refraction trace to an observed traveltime in the raw data. Another problem is that correlation of traces typically decreases the source-receiver offset of the virtual trace because traveltimes are subtracted and are associated with shorter raypaths. To overcome this, Bharadwaj and Schuster, Mallinson et al. (2011), andHanafy et al. (2011) presented an extension of refraction interferometry so that the receiver spread could be extended to its maximum recording extent, and the absolute arrival time can be properly accounted for. This new method creates virtual far-offset refraction arrivals by

Because the earth is predominately anisotropic, the anisotropy of the medium needs to be included in seismic imaging to avoid mispositioning of reflectors and unfocused images. Deriving accurate anisotropic velocities from the seismic reflection measurements is a highly nonlinear and ambiguous process. To mitigate the nonlinearity and trade-offs between parameters, we have included anisotropy in the so-called joint migration inversion (JMI) method, in which we limit ourselves to the case of transverse isotropy with a vertical symmetry axis. The JMI method is based on strictly separating the scattering effects in the data from the propagation effects. The scattering information is encoded in the reflectivity operators, whereas the phase information is encoded in the propagation operators. This strict separation enables the method to be more robust, in that it can appropriately handle a wide range of starting models, even when the differences in traveltimes are more than a half cycle away. The method also uses internal multiples in estimating reflectivities and anisotropic velocities. Including internal multiples in inversion not only reduces the crosstalk in the final image, but it can also reduce the trade-off between the anisotropic parameters because internal multiples usually have more of an imprint of the subsurface parameters compared with primaries. The inverse problem is parameterized in terms of a reflectivity, vertical velocity, horizontal velocity, and a fixed [Formula: see text] value. The method is demonstrated on several synthetic models and a marine data set from the North Sea. Our results indicate that using JMI for anisotropic inversion makes the inversion robust in terms of using highly erroneous initial models. Moreover, internal multiples can contain valuable information on the subsurface parameters, which can help to reduce the trade-off between anisotropic parameters in inversion.

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With the increase in accuracy required for seismic exploration one must include more physics in modeling seismic waves. In this paper we extend Full Wavefield Modeling (FWMod) to handle anisotropic media. FWMod is an integral-based approach that model's reflection events. It considers primary as well as multiple scattered reflections. We make use of the pseudo-elastic assumption for the acoustic wave-equation for anisotropic media to simplify the equations and reduce the cost associated with modeling. This introduces anisotropic kinematics into the acoustic wave equation, however this comes with two main limitations. The first limitation is that a pseudo S-wave is generated when the source is on, or near, an anisotropic layer. The pseudo S-wave manifests as a diamond shaped shear wave. The second limitation is an exponential growth in the solution for negative values of η. Attenuating these artifacts in finite-difference modeling is difficult and, in many cases, suboptimal. However, with a phase shift method such as FWMod attenuating these limitations is relatively straightforward. The pseudo S-wave can be clearly recognized in the absolute value of the phase shift extrapolator. In this domain it can be identified and attenuated. As for negative values of η, with this type of representation of the extrapolators, one can ensure that we always have evanescent decay rather than exponential growth in the solution. We include the anisotropic kinematics in the FWMod formulation and demonstrate the effectiveness of this method using a synthetic model.