Discussion on Commonly Methods for Analysis of Drill String Acoustic Spectral Characteristics

Finite difference method and transfer matrix method were used to get spectrum response curve of unit impulse function signal to research the spectrum characteristics of acoustic traveling though the drill string. Similarities and differences of the two methods were discussed through analysis of spectrum curve get from the two approaches. The results show that: The distribution of band-pass and band-stop get by the two calculating methods is basically the same, some transmission coefficient of finite difference method is less than 1, is not completely transmission phenomenon. Analysis of the reason for this is that the transfer matrix method is an analytic method, finite difference method is a numerical algorithm. From the calculation precision of speaking, analytic algorithm is higher than that of numerical algorithm. But to verify the reliability of two methods needs based on laboratory experiment or field test.