Broadband Seismic - How Many Octaves are Enough for Improved Temporal Resolution?

Broadband seismic improves resolution; increases the reliability of quantitative estimates from the seismic data and its inversion to impedance. It is also important for FWI for obtaining velocity information to image deep targets. While there is no formal definition of the broadband seismic, reviewing case histories over the last two years, it is possible to come up with the following description of it: broadband seismic is the final processed surface seismic data set that has a flat amplitude spectrum over many (4-6) octaves starting from around 1.5-2 Hz and with zero phase spectrum. Various authors have showed the impact of increasing high frequency content and bandwidth on seismic resolution using synthetic examples. Here, I derive a relationship between temporal resolution on one hand and the frequency content of the data in terms of bandwidth in octave and the highest frequency component on the other hand. Based on this relationship, it turns out that little improvement in temporal resolution is gained by going beyond 4 or 5 octaves. However, for FWI the requirements for low frequencies are more demanding and the efforts should continue to improve the generation and recovery of data with frequencies below 1.5 Hz.