Case studies in 3D interbed multiple attenuation

Abstract

Attenuating water-column multiples with 3D SRME has become common practice, but interbed multiples are not attenuated with this technique since these multiples do not reflect from the free surface. Interbed multiples are often reflected between closely spaced events, giving them an effective velocity very similar to primary events. Because there is little moveout discrimination, interbed multiples do not respond to Radon multiple attenuation or other moveout-based techniques. Extending the concept of SRME to predict interbed multiples is not a new idea, but the 3D implementation was not widely applied until recently. The increase in available computing power has made 3D IME (interbed multiple elimination) a viable option. This paper will discuss a synthetic data set, a Gulf of Mexico marine data set, and an Egyptian Western Desert land data set. Attenuating interbed multiples is an important issue in exploration, especially in the Middle East, where this type of multiple is particularly problematic because the anti-multiple tools based on velocity differences do not work well in this geologic setting. In the salt provinces, attenuating interbed multiples is of particular importance as their presence greatly inhibits interpretation. In addition, removing this class of multiple is very helpful in understanding dirty salt.