Research On Geophone Coupling System Based On Elastics Theory

The coupling effect between geophones and medium in vicinity acts as a key role in data acquisition during seismic exploring. Consequently, the way to figure out the property of a certain geophone-medium coupling system attracts the concern of geophysicists home and abroad. We introduce a research on geophone-medium coupling issue based on elastics theory by this paper, which is unprecedented in domestic domains.Considering the limitation of oscillation coupling model, we bring the idea to build a rigid cylinder and define coupling coefficient for further work. Then the velocity field of point source is developed with elastics theory and green function. Finally the function of elastic model is formulated after involving reciprocity theory.Next, we aim to illustrate how the press wave velocity, Poisson rate, density of medium and the weight of geophone, length and radius of spike affect the response of coupling system by numerical simulating. Numerical results show that loose medium with higher P-wave velocity, lower Poisson rate or higher density may have higher frequency system response, while the same changes have slighter effects to solid ones. Using heavier geophone or thicker spike will bring lower frequency response to loose medium coupling system. And longer or thinner spike may cause higher frequency response in solid medium.By comparing the simulating results from elastic coupling model and oscillation coupling model, several conclusion are put forward as fellow. (1) The frequency of response from elastic coupling model is higher than oscillation ones while they are in loose medium. (2) The response of elastics coupling model is near to oscillation ones in frequency while they are in solid medium. (3) The difference between the responses of two models theoretically is caused by different preconditions of them.Then compare among a record from seismic prospecting projects and models simulations is unfolded in the final section. By that we find elastics coupling model match the record well in lower frequency area, while oscillation coupling model do well in higher frequency. So a way to combine these characters are brought out, whose feasibility and efficiency are supported by seismic data.