LIFT: a new and practical approach to noise and multiple attenuation

There is perhaps no greater frustration to the seismic interpreter than to have signal obscured by noise. This is a common occurrence and many noise attenuation algorithms have been developed to address it. Most methods attempt to separate the desirable signal from the undesired noise, usually by making use of some transform into a domain where the signal or noise is modelled mathematically, and signal and noise can be separated. Most historical noise suppression methods stop at separating noise and signal. That is, the signal model itself is the output of the noise attenuation program. Some methods go slightly further by adding back a percentage of the original input data. LIFT, Core Lab's new proprietary amplitudefriendly technique for attenuating noise and multiples, takes a new approach by adding back an estimate of the signal removed during the signal modelling, rather than adding back a percentage of the original data. This is a fundamental shift in noise suppression strategies. It is an approach that is very flexible in that it can incorporate a variety of application domains, filtering tools, and new technologies and ways of modelling data – including future technologies as they are developed. It is an approach that greatly improves signal preservation, making quantitative AVO and rock properties analyses much more reliable. Also it is a robust amplitudepreserving way to precondition data for prestack migration, avoiding migration artifacts and costly re-runs. The primary amplitudes after LIFT are trustworthy, making prestack migration with AVO now a realistic option.