Publications

In recent years, the deep water area of the Eastern Makassar Strait has becoming a target for hydrocarbon exploration in Indonesia. 3D seismic surveying, as an exploration tool, has been carried out in some of the blocks. Due to water-bottom shape and reflectivity complexity, the seismic data resulting from one of the surveys showed strong and complex surface-related multiples that conceal the underlying primary seismic energy. Without an effective demultiple technique, the resulting image from data processing can give limited information. Recently WesternGeco introduced 3D General Surface Multiple Prediction (3D GSMP*) as a solution to attenuation of multiples in this type of environment. In this paper, WesternGeco together with StatoilHydro, illustrate and compare the successful use of this approach with a case history from the newly acquired data of the Karama block in the Eastern Makassar Strait. In a complex water-bottom area like the Eastern Makassar Strait, surface-related multiples will contain a cross line or “3D component. The Downward Reflection Points (DRP) of the multiple travel paths are not in line with the source and receiver points. Any type of 2D demultiple algorithm that assumes the multiples are in the source -receiver plane, will fail to predict and attenuate the multiples and may harm the primaries. In theory, conventional 3D Surface Related Multiple Elimination (3D SRME) can provide a more accurate solution to these types of multiples. However, in practice where the source and receiver geometries are not regular, conventional 3D SRME as typically implemented will not produce an accurate multiple prediction model. 3D GSMP is a practical approach to 3D SRME that can handle the irregularities in real life survey geometries and provides a superior multiple model prediction. Without 3D GSMP, strong residual multiples obscure the seismic image, making any kind of seismic interpretation extremely difficult. 3D GSMP provided a far better match to the surfacerelated multiples than either 2D SRME or conventional 3D SRME and resulted in minimal or no residual multiples in the final image. A far better structural image was achieved, providing more confidence during the exploration evaluation.