一种无拉伸畸变的动校正方法

A NMO correction method without stretching distortion

动校正是地震数据处理的重要内容之一,采用常规动校正方法会产生拉伸畸变现象,在浅层和大炮检距处尤为明显,给地震资料的后续处理造成了不利影响。为此,分析了常规动校正方法产生拉伸畸变的原因,给出了动校正量可能的修正范围,提出了无拉伸畸变的动校正方法:1将近炮检距地震道进行常规动校正并叠加,得到标准道;2对地震道中每个时间样点的动校正量在给定的范围内进行修正扫描,并将常规动校正量加上修正量作为更新动校正量;3以待校正的时间样点为中心开时窗,使用更新动校正量进行动校正,并计算校正后时窗内数据与对应标准道数据的互相关系数;4将最大互相关系数对应的更新动校正量作为该样点的最终动校正量,以此实现无拉伸畸变动校正。模型数据测试和实际资料试处理结果显示了方法的正确性和有效性。

Normal moveout （NMO） correction is one of the important procedures in seismic data processing. The conventional NMO correction method usually causes stretching distortion, especially in shallow layer and at large offset, which will adversely affect the subsequent processing of seismic data. Therefore, we analyzed the reasons for generating stretching distortion by conventional NMO correction and calculated the possible revising range of NMO correction values＇and then a NMO correction method without stretching distortion was proposed. Firstly, we stack the nearoffset traces after conventional NMO correction and take the stacking trace as standard trace. For every time sampling data, we estimate the updated NMO correction values by giving different disturbances which are selected within the revising range and added to the conventional NMO correction values. Moreover, we select a time window centering on this sampling data and carry out NMO correction using every updated NMO correction value, then calculate the cross-correlation coefficient of the corrected data in this window and corresponding standard trace. Finally, the best NMO correction value is defined as the value corresponding to the largest crosscorrelation coefficient, to realize NMO correction without stretching distortion The accuracy and effectiveness of this method are proved by model and practical data processing.