Q Compensation Methods And The Application In The Seismic Data Processing

When seismic waves travel through the earth, amplitude will be attenuated and the phase will be distorted because of the anelasticity of the media. An effective Q compensation is necessary when an usual seismic processing is taken on. The phase of the earth filtering is a complicated problem. Based on the Futterman amlitude and phase velocity dispersion pair, the relationship of Q-factor and the attenuation factor a is discussed. Nonelasticity attenuation principle is formulated during the seismic waves traveling. Using the Hargreave wave equation exact solutions, synthetic records with attenuation and dispersion are made, which involves complete wavefield information, but calcuated amout is large. Modified Hale algorithm is adopted for Q compensation. Deconvolution computation of the target signal and the deconvolution inverse filtering factors, amplitude and phase are both compensated. Computing velocity of this algorithm is quick and the effect is good as well.Q-factor is a very important petrophysical parameter. The resolution of the seismic image could be improved through inverse Q filtering, but the point is the reliable estimate of the Q-factors. Q-factors are commonly estimated from vertical-seismic-profile data or post-stack surface seismic data, and then compensated for attenuation. A new method for estimating Q-factors from common midpoint(CMP) gathers is adopted in this paper. Considering the influence of the offset and travel time to the seismic peak frequency variations, this method estimates the interval Q-factors with layer-stripping approach. Q-factors are estimated and inverse Q filtering is completed with the synthetic CMP gathers. Experiment results are good and comparison analysis are given.Q-factor is related with inner friction. The less the inner friction the bigger the Q-factor. Q-factor describes the variance situation of the absorption, when seismic wave travels through the fluid medium. Analysing correlation of the Q-factor and fluid, so we can identify the fluid effectively.