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酒西盆地面积很小,地层分割性强,岩石介质的理化参数变化范围很大,使盆地内的地震波速度在横向和纵向上变化剧烈。但是,速度的变化在横向和纵向上具有规律性。根据速度变化的这一特点,我们利用测区内已知钻井的速度曲线或速度谱点的速度曲线,求出各个地震层位的分层变速曲线。然后用分层变速速度对地震反射层T_5和T_s作时-深转换成图,与测区内36口井进行投井深度误差分析,结果投井深度相对误差均在5％以内(个别井除外),符合本区成图精度要求。而采用本区的综合速度进行时-深转换成图,T_s层投井深度相对误差均在10％以上,超出了本区的成图精度要求。由此说明,在酒西盆地应用分层变速速度成图是正确的,较好地解决了该区地震资料进行时-深转换的速度问题。
Jiuxi basin has a small area and strong stratigraphic division. The physical and chemical parameters of rock media vary greatly, which makes the seismic wave velocity in the basin change drastically in both horizontal and vertical directions. However, the change in speed is regular in the horizontal and vertical directions. According to the characteristics of velocity variation, we use the velocity curves of known drilling velocity or velocity spectral points in the survey area to find the stratified velocity curves of each seismic layer. Then the time-depth conversion of the seismic reflection layers T_5 and T_s by stratification speed-changing into a graph and the error analysis of pit casting depth with 36 wells in the surveyed area resulted in the relative errors of pit casting depth being within 5% (except for individual wells ), In line with the accuracy of mapping in this area. However, using the integrated velocity of this region for time-depth conversion into a graph, the relative errors of the depths of the T_s layer are all above 10%, which exceeds the accuracy of the mapping in this area. Therefore, it is correct to apply the stratification speed change map in Jiuxi basin to solve the velocity problem of time-depth conversion of seismic data in this area.