The Complementary Combination Stimulating Methods For Controllable Seismic Sources And The Experimental Study

Seismic exploration is a artificial method (occasionally with natural seismic exploration data)which use explosives or non explosive source seismic waves, It is a geophysical prospecting methodwhich according to the elastic rock, through study the law of seismic wave propagates in stratum,to prove underground geological structure and morphology. In reflection seismic exploration, theseismic signals that seismograph detected tend to be noisy (things which hinder effectiveidentification and other track components are called interference wave), according to appearanceregularity of the interference wave, the interference can be divided into the two kinds with regularsand the irregulars (random disturbance). Interference wave shows some regularity in time or space,Its energy is generally stronger than effective wave, the apparent velocity and arrival time is alsodifferent with significant wave, usually includes multiple wave, surface wave and sound waves andothers related to stimulate wave; Irregular interference wave usually includes random disturbanceand environmental noise, which makes the processing and interpretation of seismic records becomecomplicated and inaccurate. The seismic source is the source of the seismic signal, its quality willdirectly decide the success or failure of the whole process of seismic exploration, just as if photo’sexposure itself is bad, so no matter how many modificatory soft wares are used behind, the resultsis meaningless. The effect of seismic source is free energy to the surface or layer, form into theelastic wave which spread to the ground. And the vibrator is a kind of the most successful one so far,the so-called Vibroseis is a seismic source which uses small control energy, a long time impactexcitation wave to realize the excitation wave of impact seismic source. The characters of Vibroseisare low amplitude, high effect, energy accumulation for a long time, the frequency compositionunder control. Its working principle is launching continuous scanning signal with the form of seismicwave to the underground, seismic wave will be reflection in the interface of different geologicalstructure or underground target body surface, then the reflection wave will received by the surfacearray detector which connected to geophone seismometers. Seismometers then makes the receivessignal into the pulse signal with time delay information through relevant processing technology,then make a series of data processing(such as statics correction and NMO correction, filtering,velocity analysis, and add the head of seismic trace), for initial processed data, you can take thenext step, namely the data inversion, so as to realize to the exploration of stratigraphic information.This paper carried out the study of the complementary combination stimulating methods forcontrollable seismic sources and the experimental methods, which provided for the basis of the newdevelopment and further application of Vibroseis in seismic exploration.Impact seismic sources have the characteristic of strong energy, and the swept impactseismic technique (SIST) can significantly improve the anti-interfering capability and increase exploration depth, but the SIST technology has higher requirements for the impact sequence lengthand accuracy, so they always have some limitations. A variety of single seismic sources combinationcan overcome the shortcomings and express the advantages of each source so as to make Seismicprospecting signal much better. This paper researches complementary combination stimulatingtechnique for different types of controllable seismic sources. Because of the increase in therandomness of the composite source signal, the technique does not reduce the signal-to-noise ratioand resolution of seismic records when the length of impact sequence is decreased. The results ofcorrelation analysis, the seismic numerical simulation and the actual seismic experiment are allconfirmed the effectiveness of the complementary combination stimulating technology.In general, the paper elaborated the function of vibroseis in seismic exploration, the relatedtechnology and scanning methods of hydraulic pressure source and coding source in the field ofseismic exploration, complementary combination source relevant decoding principle and so on.Paper’s main achievements are as follows:1. Firstly, the correlation decoding principle of vibrator is studied, and the source of softwareand hardware design and the operation method of the hydraulic source and the coding source;2. Take the combination of single impact seismic source and single vibration seismic source as anexample, correlation analysis and seismic numerical simulation of complementary combinationstimulating technology has carried on, which do the research of complementary combinationstimulating technology, this study has drawn a theoretical basis for the complementary combinationstimulate technology;3. Using vibroseis and centralized seismograph to do the experimental study, a large number oftest data show that the complementary combination stimulate technology has increased therandomicity of combination source signal, optimized the performance of the correlation wavelet,reduced related noise interference of the earthquake decoding records.Did the experiment on the same premise of the environment and other apparatus, handled thecollecting data, by contrast with the data obtained from single hydraulic source, I got the result thatcomplementary combination stimulating technology can effectively expanded the seismic sourcesignal bandwidth, improves the resolution of seismic record.