Research On Passive Source Reflection Seismic Exploration

Seismic exploration has the advantages of exploration depth and resolution,and is an important branch of geophysical methods.However,its high collection cost,difficulty in collecting complex areas(prohibited blasting areas,steep mountainous areas,etc.)and other difficulties have limited its wide application in the field of minerals and engineering exploration.Passive source reflection seismic exploration method is an emerging research direction,because it does not require artificial seismic source for excitation,but uses natural vibration signals,such as natural earthquakes,structural rupture,and background noise,etc.,which can effectively reduce acquisition costs and solve the problem of inability to shoot And other issues.The method first reconstructs the virtual shot gather records by performing seismic interference calculation on the recorded seismic signals,and then performs conventional seismic data processing on the virtual shot gather records to obtain the imaging results of the exploration area.During the reconstruction process,the superimposed comprehensive effect and correlation will cancel the seismic wave propagation path to remove the influence of complex geological structures on wave propagation,and turn the disordered noise signal into a useful signal.But at the same time,passive source reflection seismic exploration also faces problems such as weak body wave signals and few available reference cases.Based on this,this paper conducted passive source seismic exploration experiments in Inner Mongolia shallow coverage area and an engineering exploration area in Tibet.This paper firstly deduces the seismic interferometry(the main algorithm of passive source reflection seismic exploration)from homogeneous medium to non-uniform medium,and uses the acoustic wave equation finite difference algorithm for forward simulation to explore the field source distribution and the length of passive source data acquisition.The influence of other factors on the reconstructed quasi-fire collection records.The application of surface waves and body waves in the reconstructed quasi-shot set records was discussed separately.The surface waves in the quasi-shot set records were used to invert the thickness of the cover layer,and the thickness of the cover layer wasobtained.The quasi-shot collection records reconstructed by body waves are processed by the conventional seismic data processing process of reflected waves,and can be analyzed and compared with the active source results.Through a series of study and research,this paper shows that the passive source reflection seismic exploration method has good application effect in Inner Mongolia and Tibet.It is an important future option for low-cost area exploration.