THE OPTIMIZED PROCESS OF ANGLE GATHERS FOR SEISMIC DATA COLLECTED BY CHANGING INTERVAL CHANNELS AT BLAKE OCEAN

The Blake Ocean is rich in marine gas hydrate. The seismic data from Leg ODP164 clearly shows an excellent indication of BSR.Combining the p-wave velocity, s-wave velocity, density information from well logging and seismic angle gathers stack data to do the pre-stack elastic wave impedance inversion, we achieved a significantly effective and accurate results for recognition of the gas hydrate zone. However, we found that the inversion is closely related to the quality of angle gathers. Because the acquisition in this area uses a changing-trace interval, making the fold uneven, the quality of angle data of different angle has a big difference. In order to provide high quality angle stack data for pre-stack elastic wave impedance inversion, it's necessary to carry out the process to improve the quality of the angle gathers. In this study, we adopt precise parabolic Radon transform and binning optimizing processing, better supplementing the information of the loss offsets. As the result, the angle information becomes more balanced, the energy of amplitude of angle gathers and the event's continuity are both improved. Moreover, the conclusion of forward modeling proves that the Radon transform will not cause significant change to the original channel data. According to the comparison of sensitive attribute, which is calculated from pre-stack elastic impedance inversion, we can see clearly that the inversion profile obtained from the optimized gathers has greatly improved the hydrate layer's abundance changes and the BSR characteristics. This method also gives a good reference to process similar seismic data before the pre-stack elastic impedance inversion.