Abstract: The invention relates to a computer-implemented method for generating an image of a subsurface of an area of interest from seismic data. The method comprises providing seismic wavefields, providing a zero-offset seismic wavefield dataset, determining a seismic velocity parameter model w(x) comprising an initial model w0(x), a low frequency perturbation term ?mb(x) and a high frequency perturbation term ?mr(x), determining an optimal seismic velocity parameter model wopt(x) by computing a plurality of iterations, each iteration comprising calculating and optimizing a cost function, said cost function being dependent on the zero-offset seismic wavefield and on the low frequency perturbation term ?mb(x) as a parameter in the optimization of the cost function, the high frequency perturbation term ?mr(x) being related to the velocity parameter model w(x) to keep the provided zero-offset seismic wavefield data invariant with respect to the low frequency perturbation term ?mb(x).

Abstract: The invention relates to a computer-implemented method for generating an image of a subsurface of an area of interest from seismic data. The method comprises providing seismic wavefields, providing a zero-offset seismic wavefield dataset, determining a seismic velocity parameter model w(x) comprising an initial model w0(x), a low frequency perturbation term ?mb (x) and a high frequency perturbation term ?mr(x), determining an optimal seismic velocity parameter model wopt(x) by computing a plurality of iterations, each iteration comprising calculating and optimizing a cost function, said cost function being dependent on the zero-offset seismic wavefield and on the low frequency perturbation term ?mb(x) as a parameter in the optimization of the cost function, the high frequency perturbation term ?mr(x) being related to the velocity parameter model w(x) to keep the provided zero-offset seismic wavefield data invariant with respect to the low frequency perturbation term ?mb(x).

Abstract: The method processes, for each of a plurality of shots at respective source locations, seismic traces recorded at a plurality of receiver locations. Common-mid-point-modulated data are also computed by multiplying the seismic data in each seismic trace by a horizontal mid-point. A depth migration process is applied to the seismic data to obtain a first set of migrated data, and to the mid-point-modulated data to obtain a second set of migrated data. For each shot, aperture values are estimated and associated with respective subsurface positions. A migrated value for a depth and an aperture in a surface aperture common image gather at a horizontal position is a migrated value of the first set of migrated data for a shot such that the estimated aperture value associated with that subsurface position is the aperture.

Abstract: The method processes, for each of a plurality of shots at respective source locations, seismic traces recorded at a plurality of receiver locations. Common-mid-point-modulated data are also computed by multiplying the seismic data in each seismic trace by a horizontal mid-point. A depth migration process is applied to the seismic data to obtain a first set of migrated data, and to the mid-point-modulated data to obtain a second set of migrated data. For each shot, aperture values are estimated and associated with respective subsurface positions. A migrated value for a depth and an aperture in a surface aperture common image gather at a horizontal position is a migrated value of the first set of migrated data for a shot such that the estimated aperture value associated with that subsurface position is the aperture.

Abstract: Post-migration common image gathers (CIGs) are generated in a dip angle domain from measured seismic data. From a CIG, a hybrid Radon model is determined, including a reflection model related to concave features in the CIG and a diffraction model related to linear features in the CIG. The reflection model is transformed with a reflection Radon operator applied along inversion trajectories restricted around apices of the concave features to obtain reflection data. The diffraction model is transformed with a diffraction Radon operator to obtain diffraction data. The reflection and diffraction data at different horizontal positions can then be combined and summed to generate a migrated image of the subsurface.

Abstract: The method processes input including, for each of a plurality of shots at respective source locations, seismic traces recorded at a plurality of receiver locations. Offset-modulated data are also computed by multiplying the seismic data in each seismic trace by a horizontal offset between the source and receiver locations for said seismic trace. A depth migration process is applied to the seismic data to obtain a first set of migrated data, and to the offset-modulated data to obtain a second set of migrated data. For each shot, offset values are estimated and associated with respective subsurface positions, by a division process applied to the first and second sets of migrated data.

Abstract: A method for analyzing seismic data by generating a post-migration common image gather in a dip angle domain from measured seismic data; detecting concave features related to reflection events in the common image gather and apexes; filtering out part of the concave features in the common image gather in a vicinity of the detected apexes; applying a hybrid Radon transform to the filtered common image gather to separate residues of the concave features from other image features related to diffraction events; and applying an inverse hybrid Radon transform to an image containing the separated features related to diffraction events to obtain a transformed common image gather in the dip angle domain.

Abstract: The method processes input including, for each of a plurality of shots at respective source locations, seismic traces recorded at a plurality of receiver locations. Offset-modulated data are also computed by multiplying the seismic data in each seismic trace by a horizontal offset between the source and receiver locations for said seismic trace. A depth migration process is applied to the seismic data to obtain a first set of migrated data, and to the offset-modulated data to obtain a second set of migrated data. For each shot, offset values are estimated and associated with respective subsurface positions, by a division process applied to the first and second sets of migrated data.

Abstract: Post-migration common image gathers (CIGs) are generated in a dip angle domain from measured seismic data. From a CIG, a hybrid Radon model is determined, including a reflection model related to concave features in the CIG and a diffraction model related to linear features in the CIG. The reflection model is transformed with a reflection Radon operator applied along inversion trajectories restricted around apices of the concave features to obtain reflection data. The diffraction model is transformed with a diffraction Radon operator to obtain diffraction data. The reflection and diffraction data at different horizontal positions can then be combined and summed to generate a migrated image of the subsurface.

Abstract: A method for analyzing seismic data by generating a post-migration common image gather in a dip angle domain from measured seismic data; detecting concave features related to reflection events in the common image gather and apexes; filtering out part of the concave features in the common image gather in a vicinity of the detected apexes; applying a hybrid Radon transform to the filtered common image gather to separate residues of the concave features from other image features related to diffraction events; and applying an inverse hybrid Radon transform to an image containing the separated features related to diffraction events to obtain a transformed common image gather in the dip angle domain.