Q inversion and comparative analysis among three methods for VSP data: CFS, SR and AA

摘要

The seismic attenuation characterized by Quality Factor (Q), is one of the key properties to reveal different stratums. This paper is aimed at discussing influencing factors of Q inversion and providing references for practical application. We elaborate three different methods to inverse Q value with VSP data, including Centroid Frequency Shift (CFS) method, Spectral Ratio (SR) method, and Amplitude Attenuation (AA) method. Comparison between the results from CFS with the other two methods is conducted on frequency band width, high Q value layers, wave field components, interface interference and thin layers. Results show that, CFS method is more stable and accurate than the other two methods for dealing with different wavefields, thin and high Q layers. Frequency band width influences inversed effects of all the three methods. The band wider, the results better. Moreover, from the application of a series of field VSP data, we can see that the Q curve of CFS method coincides with geological layers better than those of the others, which are hardly to reflect the main attenuation trend.