Point-Noise Attenuation

Narrow-band attenuation in noisy environments

Point noise attenuation is a narrow-band noise removal process based on travel times computed using the geometry of the noise source and the receiver, along with the velocity of the noise in air. Summing along these travel times for all traces of the record will result in a model trace consisting entirely of the noise from that point source. After scaling, the model trace is subtracted from the input data.

A specific example of its use would be flare noise, which is generated in tall chimneys used to vent and waste natural gas and other flammable gases that are not economic to retain. The open flames are therefore used to burn off unwanted associated gases that are extracted from the earth along with crude oil. The noise is transmitted through air and travels with the velocity of sound in air.

On a seismic record this noise is observed as low frequency interference and is coherent in nature. The main features of the flare noise, such as a low, narrow-band, spectrum, together with coherent linear moveout are used in order to model and subtract it from the input data.