The calculation and application of a near-surface Q-value model based on dual-well micrologs for a loess tableland area
Given the low resolution and poor wavelet coherence of seismic data for the loess tableland area of the Ordos Basin,this study proposed a method for calculating the near-surface Q-value model for near-surface Q-absorption compensation of seismic data.In-vestigations reveal that micrologs have been used to obtain the Q field of a whole survey area by calculating the Q value and subsequent interpolation.Based on previous research results,this study calculated the Q values of well sites and near-surface velocity values using dual-well micrologs.Then,the regional relationship function between near-surface velocity and Q was determined through fitting using the least squares method.Furthermore,the near-surface Q field of the study area was obtained using the near-surface velocity field de-rived from the tomographic inversion of the first arrival wave post basic static correction.Consequently,the near-surface Q field of the whole survey area were calculated from the Q values of microlog positions,and the near-surface Q absorption compensation of prestack gathers was achieved.As indicated by the application of the study area's seismic data,which are characterized by complex surface and subsurface conditions,the inversion of the Q field for near-surface Q absorption compensation using the method proposed in this study can effectively enhance the wavelet coherence of seismic data,broaden the frequency band,improve the log-seismic matching relation-ship,and eliminate the influence of near surface on seismic wavelets.
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