Prefiltering in SDZ-120 digital seismograph and the seismic section processing
Yan Shixin, Cheng Shutang
The First Geological Survey Division, Bureau of Oi1Geophysica1 Prospecting, Tangguantun, Jinghai Counly, Tianjin City, China, Internal postcode: 301608
Abstract：Joint data acquisition of two SDZ-120 seismographs is often used in three-dimensional seismic explorarion. Different low-cut filter modules in premplifiers bring different filtering results, so that there are phase differences between the same seismic data collected by the two seismographs respectively. Similar phase difference phenomenon also occurs when two DFS-V seismographs operate simultaneously and jointly. It is easy to find the phase difference phenomenon in above cases. However, the phase difference phenomenon can hardly be found when different seismic cres use respectively the same seismographs, as mentioned above, in an exploration area. It is necessary, therefoe, to use same low-cut filter modules in seismic data acquisition in an exploration area. If different low-cut filter modules are used in same data acquisition, differently-filtered seismic data must need their own shaped wavelets in data processing, so that phase-unified seismic sections can be obtained in an exploration area, resulting in good seismic interpretaition. If not so, we only can obtain wrong geological result.
