Based On The Prony Transform Of Seismic Wave Absorption And Attenuation Characteristic Extraction Method

Seismic wave propagation in the near surface, because of the underground rock has the absorption of seismic wave, it makes the high frequency energy decay. Seismic wave attenuation mainly comprising:the process of seismic wave propagation in spherical diffusion effect, formation transmission effect, the viscoelasticity properties of rock skeleton; porosity of the rock, the pore fluid composition, etc. In the first two attenuation and the frequency of seismic wave has little relationship, after several absorption attenuation has a great relationship with the frequency. The Prony transform can describe the relationship between the frequency and the attenuation coefficient. Therefore, it can be applied to detect abnormal absorption band.All along, the study of absorption for the reservoir, the general method of Fourier transforms, it indirectly through linear filtering to strike the absorption coefficient, restricts the prediction accuracy. The Prony transforms method use damped harmonic signal decomposition, direct calculation of absorption coefficient by nonlinear filtering, and has multi-level quality control, improve the gas reservoir prediction accuracy.This paper begins with the introduction of the seismic wave absorption and attenuation of the various mechanisms, listed respectively from the macro and micro. From a macro point of view, geometrical spreading, inelastic attenuation, transmission loss, mode conversion, scattering and refraction angle and the critical angle; from the microscopic point of view are friction, irreversible thermal conduction, crystal imperfection, electrochemical influence, capillary effect and fluid flow. Then cited various factors of seismic wave attenuation, including lithology, frequency, pressure, temperature, strain amplitude and the velocity with pore fluid saturation. Based on the stratigraphic absorption, discusses the seismic wave absorption and attenuation parameters such as quality factor, the relationship between the absorption coefficient and the logarithmic decrement and between the attenuation coefficient and mutual. According to the principle of Prony algorithm written in Prony transform inMATLAB software, achieving transformation Prony fitting, analysis and reconstruction of signal. Then, through the basic steps of prony transform, select the seismic data, conduct prony transform, verify prony fitting algorithm. The Prony method can quickly obtain measurement data according to the required information, and can be a good fit to the data.In 1999, Mitrofanov based on the model of the effectiveness of filtering prony. These models indicate to us that in the seismic data processing, in order to obtain the relevant medium structure and hydrocarbon potential area with the information, the Prony filter has great potential. Through the Prony filter step and the optimal parameter settings, Prony absorption filtering method is applied in a seismic profile. Performed absorption filtering process on the seismic, while the original seismic profiles were compared with the filtering results figure, study the formation of gas analysis.Prony absorption filtering technique for nonlinear filtering of seismic signal by harmonic damping, can directly obtain the absorption coefficient of the reservoir, so that the absorption attenuation anomaly acquisition and analysis are more convenient. Meanwhile Prony absorption filtering in multistage control conditions, the prediction accuracy of gas bearing is higher than Fourier transform technology. Filtered through the absorption cross-section, the response characteristic is compared with the input profile events weaken or disappear. According to the parameter selection results, it is necessary to increase the well point information to determine the optimal parameters of Prony absorption filtering. Seismic wave propagation in gas reservoirs will occur strong energy absorption response characteristics, but this phenomenon is difficult to be found on the original seismic record. However, after absorbing filter, this phenomenon can be found. So we can better facilitate the identification of gas reservoir.