Study On The Methods Of Phase Analysis And Correction Of Seismic Data

With the development of seismic exploration to the direction of high precision andhigh fidelity, the phase features of seimic wavelet is getting more researchers’ attention.Now the study on the response of the amplitude to formation has been gradually improved.But the study and utilization of phase spectrum is relatively weak. In many cases onlyamplitude spectrum is used but phase spectrum is abandoned because of its complexity, sothe response of the wavelet phase to the stratigraphic structure is ignored. Now greatprogress has been achieved in the field of signal process, and the comprehensive study onsignal analasis is essential, especially the study on phase characteristics becominginevitable.Three methods of phase spectrum calculation are firstly introduced, and they areabout the principal value phase spectrum, unwrapped phase spectrum and continuous phasespectrum. The method of continuous phase pectrum is finally choosen. Through changingthe search interval, continuous phase becomes a monotonic function and meets theproperty of delay in the positive period.Seismic wave is affected by many factors during propagation, which makes the phasechange. In addition, data processing also distorts the phase of seismic record to varyingdegree. Typical models were established based on the main factors which impact the phaseof seismic wave. By forward modeling, the impact of some factors on the phase of seismicwave were analyzed and tested, including viscoelastic medium formation thickness,rhythm layer, and progressive layers and bending interface.Based on the theory that using pseudo entropy of seismic reflection data couldforecast the direction of sedimentary facies, I established a typical depositional model. Byforward modeling, it is confirmed that the entropy becomes greater along the direction ofsedimentary deposition, especially at the end of deposition the pseudo entropy becomes thelargest. Combined with the actual material, the relationship between seismic wave phasechange and sedimentary characteristics is analyzed by the entropy value. Four methods of phase correction are introduced. By doing phase correction to actualmaterials, it is discovered that the continuity of reflections and characteristics of wavegroup on the sections become better after inverse Q phase correction, constant phasecorrection, subsection frequency phase correction and wavelet consistent phase correction.This improves the resolution of seismic data to some extent, and verifies the effectivenessof various phase correction methods.Through the model test and actual data analysis, it is proved that geological structuremore influences the phase of seismic reflection wave, and the seismic phase change isassociated with formation sedimentary characteristics. This provides the possibility ofusing seismic data phase to study the underground structure. In terms of phase correction,although all sorts of phase correction methods have some effectiveness, the phaseinformation caused by strata structure have not been completely recognized, and. phaseeffects can not be completely removed by certain corrections. In a word, the field of phaseinformation awaits deep studies.