Increasing signal-to-noise ratio of marine seismic data: A case study from offshore Korea

Subsurface imaging is difficult without removing the multiples intrinsic to most marine seismic data. Choosing the right multiple suppression method when working with marine data depends on the type of multiples and sometimes involves trial and error. A major amount of multiple energy in seismic data is related to the large reflectivity of the surface. Surface-related multiple elimination (SRME) is effective for suppressing free-surface-related multiples. Although SRME has some limitations, it is widely used because it requires no assumptions about the subsurface velocities, positions, and reflection coefficients of the reflector causing the multiples. The common reflector surface (CRS) stacking technique uses CRS reflectors rather than common mid-point (CMP) reflectors. It stacks more traces than conventional stacking methods and increases the signal-to-noise ratio. The purpose of this study is to address a process issue for multiple suppression with SRME and Radon filtering, and to increase the signal-to-noise ratio by using CRS stacking on seismic data from the eastern continental margin of Korea. To remove free surface multiples, SRME and Radon filtering are applied to attenuate the interbed multiples. Results obtained using synthetic data and field data show that the combination of SRME and Radon filtering is effective for suppressing free-surface multiples and peg-leg multiples. Applying CRS stacking to seismic data in which multiples have been eliminated increases the signal-to-noise ratio for the area examined, which is being considered for carbon dioxide capture and storage.