Amplitude-preserving migration and its application to imaging of a BSR in marine multichannel seismic reflection data
Amplitude-Preserving (AP) migration has been developed to obtain structural image and to recover angle-dependent reflectivity information from surface seismic reflection data, which is the basis to perform Amplitude Versus Angle (AVA) analysis. The strategy of the AP migration method is based on combining a Common Focus Point (CFP) technique for removing wave field propagation effects and an application of a weight function for preserving amplitudes during the migration process. The AP migration is designed as a separate program from modeling algorithms by requiring migration operators in the form of seismograms. All required quantities (e.g., traveltime, amplitude, phase and angle) for the amplitude preserving weight function are estimated directly from seismogram operators. The AP migration has been successfully applied to synthetic data sets ranging from simple to complex model. As an application to a real data set, the AP migration is applied to marine MCS reflection data collected across the continental margin offshore Oregon (line OR89-02). These data reveal hydrate distribution through the presence of bottom simulating reflectors (BSRs). BSRs are imaged in terms of angle-dependent reflectivity gathers as well as structural image. Furthermore, AVA analysis and modeling are performed to estimate the possible (lithological) properties of the seafloor and the BSR responses.