Abstract: A system and method for seismic imaging of a complex subsurface volume of interest may include generating partial image gathers, aligning each of the partial image gathers based on frequency-dependent phase information to created aligned partial image gathers, and stacking the aligned partial image gathers to produce a seismic image of the subsurface.

Abstract: According to a preferred aspect of the instant invention, there is provided herein a system and method for extending zero-offset or stacked wave-equation illumination analysis into the angle-gather domain, where it becomes an appropriate tool for assessing the effects of complex overburden on AVA response. A preferred method for doing this involves first creating an angle gather that has a perfect AVA response (i.e. a constant amplitude as a function of angle). This gather is then preferably used as a reflectivity map that is fed into a demigration process which creates modeled data that by construction carries with it a completely flat reflectivity signature. Remigration of such a data set then results in a gather on which any amplitude variation is more likely to be a measure of illumination effects alone. The resulting AVA signature on the gather can then be used to assess the validity of the AVA response on modeled or actual data, resulting in a useful AVA risk analysis.

Abstract: According to a preferred aspect of the instant invention, there is provided herein a system and method for extending zero-offset or stacked wave-equation illumination analysis into the angle-gather domain, where it becomes an appropriate tool for assessing the effects of complex overburden on AVA response. A preferred method for doing this involves first creating an angle gather that has a perfect AVA response (i.e. a constant amplitude as a function of angle). This gather is then preferably used as a reflectivity map that is fed into a demigration process which creates modeled data that by construction carries with it a completely flat reflectivity signature. Remigration of such a data set then results in a gather on which any amplitude variation is more likely to be a measure of illumination effects alone. The resulting AVA signature on the gather can then be used to assess the validity of the AVA response on modeled or actual data, resulting in a useful AVA risk analysis.

Abstract: According to a first preferred aspect of the instant invention, there is provided an efficient method of computing a 3D frequency domain waveform inversion based on 3D time domain modeling. In the preferred arrangement, 3D frequency domain wavefields are computed using 3D time-domain modeling and a discrete Fourier transformation that is preferably computed “on the fly” instead of solving the large systems of linear equations that have traditionally been required by direct frequency domain modeling. The instant invention makes use of the theory of gradient-based waveform inversion that estimates model parameters (for example velocities) by matching modeled data to field data sets. Preferably the modeled data are calculated using a forward modeling algorithm.

Abstract: According to a first preferred aspect of the instant invention, there is provided an efficient method of computing a 3D frequency domain waveform inversion based on 3D time domain modeling. In the preferred arrangement, 3D frequency domain wavefields are computed using 3D time-domain modeling and a discrete Fourier transformation that is preferably computed “on the fly” instead of solving the large systems of linear equations that have traditionally been required by direct frequency domain modeling. The instant invention makes use of the theory of gradient-based waveform inversion that estimates model parameters (for example velocities) by matching modeled data to field data sets. Preferably the modeled data are calculated using a forward modeling algorithm.

Abstract: This invention provides a method for analyzing and compensating for the deleterious effects of irregular illumination of the subsurface due to velocity variations in the subsurface and of irregular spatial sampling of seismic data. For a processing operator, like Kirchoff migration for seismic data, a conventional migration operation is carried out. The output points are analyzed for sampling artifacts caused by irregular surface sampling of the data and those due to ray path distortions. An inverse sampling operator or a filtering operator is determined that is related to dip dependent attributes at the image location. Application of the inverse sampling operator or filtering operator along with the migration or other processing operator to the seismic data compensates for the effects of irregular sampling and of raypath distortion.