Equipment-induced distortion of the seismic wavefield is an issue for any acquisition. Though vibrator distortion is considered by the seismic industry as a matter of course, that is rarely the case for sensor distortion. Sensor distortion is however a significant source of noise that affects not only explosive datasets but also vibrator datasets when acquired either in simultaneous shooting or with low-frequency expectations.
A certain number of seismic equipment specifications, like distortion, seems overlooked by seismic data end-users. In the facts, distortion corresponds to unwanted harmonic noise, which characteristics are dependent on the ones of the signal in a non-linear way.
Distortion spreads over the entire seismic bandwidth of interest and contaminates the fundamental signal we wish to sense. The level of harmonic contamination increases with lower-frequency acquisitions (stronger amplitude distortion in low frequencies, and more harmonics generated within the bandwidth of interest), but can be mitigated with the use of performant equipment.
As sensor distortion is a wholly non-modellable noise, the seismic wavefield recorded using a receiver with elevated distortion will exhibit a lesser quality and fidelity than when recorded with a low distortion receiver design. Sensor choice therefore has a significant impact on the amplitudes recorded, velocity model accuracy, images produced and results in more complex processing and interpretation.
Want to get rid of distortion? Download our article below to learn all about the major difference between source and sensor distortion.