The Study On Absorbed Attenuation And Compensation Method Of Seismic Wave

When seismic wave propagating in the underground medium, as the actual subsurface materials are viscoelastic and inhomogeneous, made part of seismic waves' elastic energy irreversible converted into thermal energy and dissipation, thus the amplitude of seismic wave is attenuated, this kind of attenuation which result of formation's viscoelastic is absorption. Due to seismic waves' high-frequency component than low-frequency component spread faster that will create the velocity dispersion, while velocity dispersion led to the phase of wavelet distortion. The absorption of formation will cause the loss of vertical resolution, it is needed that compensation the absorbed energy by the earth in the data processing. Inverse Q filtering is a data processing technology for enhancing the resolution of seismic images. It employs a wave propagation reversal procedure that compensates for energy absorption and corrects wavelet distortion due to velocity dispersion.VSP seismic records, due to particular observation mode of ground excitation and well reception, so down going wave field has small influence of noise and more accurately reflect the role of formation of filtering than reflection seismic record. Therefore, I extraction quality factor of stratum from VSP down going wave field, and implement inverse Q filtering to VSP and reflection seismic record.This paper analyzed the attenuation mechanisms and dispersion model of seismic waves in viscoelastic medium. According to the actual geological model, synthesis the corresponding zero-offset VSP records which include absorption and dispersion effects, and calculate absorption curve. Combined with research status of Q estimation algorithm, mainly introduced the basic principles of common and practical estimated Q value method which based on zero-offset VSP down going recording, and inversed the Q value from the synthetic and field zero-offset VSP down going records, respectively, and evaluated application effect of the several methods. According to inverse Q filtering algorithm domestic and foreign research present situation, derived Hale inverse Q filtering algorithm and based on the principle of wave field continuation of the inverse Q filtering algorithm, applied two inverse filtering method for the synthesis of VSP records and the ground record which based on the principle of wave field continuation, respectively. Finally carrying on the wave field continuation of the inverse Q filtering algorithm to field VSP down going record and the corresponding ground three dimensional record in which the Q value is estimated from field VSP the record, and verified this algorithms is effectiveness and practicality.