Abstract:

The quality factor describing stratigraphic absorption, which is an important physical parameter in joint inversion of PP-and PS-waves, plays an important role in the prediction of subsurface petrophysical parameters and oil and gas.On account of the physical mechanism of wave-field continuation in modified Kolsky model, and the method of calculating travel time in each layer proposed by Zhang and Ulrych, We present a method for estimating P-and S-waves quality factors based on the formula of the wave-field continuation in modified Kolsky model. We estimate a series of Q values by linear-fitting between the frequency and the logarithm of the amplitude spectrum ratio between different seismic traces, and then we obtain the Q value of each layer by selecting the better Q values and taking the average of them. In the model tests, the errors between theoretical Q values of P-and S-waves and their estimated Q values using this method are less than 2%. It shows that the Q values estimated by this method are correct and the estimated results are accurate. We apply this method to real seismic data, and get reasonable estimating results of P-waves Q value.

Key words: modified Kolsky model, estimating Q value, amplitude spectrum ratio, linear-fitting