Detection And Analysis On Directionality Of Ambient Noise In Land Seismic Exploration

In the process of actual land seismic exploration, there will be a lot of noisearound the time of the seismic wave excitation. Among which, the ambient noiseexisting before the seismic wave excitation has a great influence on the actual seismicrecords. Ambient noise exists in the whole process of seismic exploration and it isinevitable. The form and the strength are different in the different seismic explorationarea. How to suppress the ambient noise interference has become a topic which isworth to research.An effective way is that we can determine the main characterization of ambientnoise, and then we can deal with the ambient noise with object-oriented processingmeasures according to the characterization. Current study shows that ambient noiseexists in the whole process of seismic exploration, changing with the differentambient. Ambient noise has no fixed apparent velocity; it is strongly random in thetime record. Its main frequency is uncertain. But it still has rules to follow which isdetermined the source of ambient noise.The main source of ambient noise is wind. The wind source ambient noisespreads in the air and it meets the nature of the transmission. This paper introduces theconcept of ocean ambient noise directionality into the land, and uses the directionalityto describe the propagation characterization of ambient noise. Land seismicexploration ambient noise directionality can describe the propagation direction andpropagation path of ambient noise, which is the space characterization ofdirectionality. It also can describe the starting time and the duration when ambientnoise has effect on the seismic traces. We can know that ambient noise is athree-dimensional physical quantity. It describes the propagation characterization ofambient noise from the space and time respectively.This paper proposes the concept of ambient noise directionality, and models the2d,3d seismic exploration ambient noise directionality. This paper also gives amethod to detect the existence of ambient noise directionality. We apply the method tothe simulative record and the result proves that the method is effective. Then we use the detection method to deal with the China Anhui mountainmeasurement area, Daqing Lamadian forest measurement area and the Takelamagandesert measurement area, respectively. Anhui mountain measurement area adopts the2d seismic exploration system. The propagation paths needing to determine are alongthe seismic line. We have detected the actual seismic record which meets thecharacteristics of ambient noise directionality and prove the existence of ambientnoise in the mountain area according to the experiment. Daqing Lamadian forestmeasurement area and the Takelamagan desert measurement area adopt the3d seismicexploration system. Ambient noise can propagate along arbitrary path on the3dseismic observation plane. Then we apply the detection method and find thedistribution of ambient noise directionality in the two areas, respectively. Among them,the characterization of directionality is not obvious in the forest area. Because it hasmuch plant and its interference is very serious. On the contrary, ambient noisedirectionality is obvious in the desert area. We find the zonal distribution of ambientnoise propagation path.Finally we prove the existence of ambient noise directionality in the mountain,forest and desert actual seismic exploration measurement area through the largenumbers of experiments. In fact, ambient noise directionality widely exists in eacharea, and the only difference is the obvious level in different areas. Directionalitydescribes the propagation characterization of ambient noise. We can deal with theactual seismic record by coordinating the denoise method with ambient noisedirectionality in further work. And finally we can improve the quality of actualseismic record according to the new method.