Application of Inverse Scattering Series Method for Internal Multiple Attenuation – a case study

Summary

Internal multiples due to a series of subsurface impedance contrasts are commonly observed in seismic data acquired in various places such as the Gippsland Basin of Australia and the Santos Basin of Brazil. The origin of these impedance contrasts can be due to coal seams as in the case of the Gippsland Basin or geological unconformities as in the Santos Basin. Regardless of how they are generated, internal multiple reflections often pose problems to the interpretation of geological structures. They are not easily handled by conventional de-multiple methods such as Radon Transform because internal multiples often have little difference in moveout than their corresponding primary events, or predictive deconvolution because the multiple generators, and hence the multiple period, are often not known.

In this paper, we present a case study of applying inverse scattering series (ISS) based method for attenuating internal multiples. The ISS method is a data-driven approach that can predict all internal multiples of a given order without any priori knowledge of the multiple generators. Moreover, it does not require any information about the subsurface velocity field. We discuss the application of this method for handling internal multiples in Santos Basin data, and present results on both the synthetic and field data from the Tupi oilfield. The results show that the internal multiples are well predicted and, with a suitably constrained subtraction technique, the migration artifacts caused by these multiples are greatly suppressed resulting in much clearer migration image for interpretation.

Key words::

• Internal multiple
• Inverse scattering