Challenges and strategies of interbed multiple attenuation in the Asia-Pacific region

High-quality imaging is key to reservoir characterization. Any events, such as interbed multiples, which are not specifically handled by migration algorithms, generate interfering events and distort the wavelets of true reflectors, thus reducing the quality of the final image. For instance, the presence of interbed multiples has a strong impact on the interpretation of fractured basements in Vietnam (Tan et al., 2010). These interbed multiples are generated between strong reflection horizons within the Oligocene and the top of the basement. In Cooper Basin, Australia, interbed multiples generated among the coal beds lower the high-frequency content and a time delay was observed in seismic characterization (Qi, 2013). This distorted imaging is a serious problem for seismic exploration and development. Interbed multiples are a common challenge in the Asia-Pacific region. Many multiple generators, such as the seafloor, carbonate layers, coal seams or volcanic flows, are found in this region, which generate visible interbed multiples. The impact of interbed multiples on inversion and interpretation has been quantified by analysing amplitude-versus-offset (AVO) responses (Iverson, 2014). The results showed that, when isolating subtle variations in rock properties, coherent noise can negatively impact the inversion results, creating a bias in the interpretation. It can be concluded that interbed multiples should either be removed before imaging, or must be correctly addressed in imaging algorithms.