A Study On The Q Factor Inversion And Wavelet Estimation Based On Fourth-order Statistics

The attenuation of seismic wave is decided by the quality factor of sediment layer，which would seriously affect the resolution of the earthquake records and stackedprofile, and to the extent of the seismic exploration of decision accuracy and successor failure. On the other hand, the quality factor and the physical parameters of rockformation are close relationship, so we can predict the information such asstratigraphic lithology, fluid saturation, fluid type and permeability by the studying ofthe quality factor’s changes; this provide reliable material basis to the oil fieldexploration and development.For decades, many of domestic and foreign experts and scholars have done a lotof research about the decay laws and the quality factor, and put forward manymethods of inversion of quality factor. But, the use of different calculation methodsfor quality factor will get different results because the inversion is vulnerable to thedistortion of the amplitude of seismic records and the waveform. There is no one kindof method is applicable to all kinds of circumstances, and their effect depends on thequality of seismic records.Therefore, through a variety of Q value of the inversion method contrast andanalysis of the present status of study, we put forward a new kind of Q value’sinversion method form the reflection wave earthquake records. Firstly, this methodwill estimate the seismic wavelet for each layer of the seismic data based on thetheory of the zero lag slice of the fourth-order accumulation, and then we use theestimated wavelets to calculate the Q value according to the improved spectrum ratiomethod. Through the early wavelet estimation, we can eliminate the influence ofreflection coefficient and noise to the seismic wavelet and obtain a precise attenuatedwavelet. Through the improvement of the spectrum ratio method, we can improve theanti-interference ability of the Q value inversion process, so as to improve theaccuracy of the Q value inversion.Finally, after analysis of many influences on the precision of Q value calculation,we determine the range of the main parameters to the inversion method. And, through the inversion test by using the actual land stacked profile and sea pre-stack shot datarespectively, we further confirmed the feasibility of this method; through the analysisof the inversion result according to the actual data, we also realized the existeddeficiency of this method, and give the corresponding improvement in the Q valueprocess flow.