野外观测系统的检验与校正

在地震资料处理中常常发现野外观测系统不准,其后果极为严重。为了避免重复施工,改善处理效果,笔者在IBM3081系统上编制了利用初至波对野外观测系统进行检验和校正的程序。文中介绍了两种校正方法:其一是只作炮检距校正。根据工区的小折射、井口时间、反射记录等资料提供一条或几条比较准确的初至时距曲线,作为标准曲线,然后将从实际共炮点道集中拾取的初至曲线与标准初至时距曲线相比较,确定出实际初至曲线所对应的炮检距,并对各个地震道的空间属性进行修改。对某三维工区的处理结果表明,该方法的效果良好。其二是先用迭代方法加误差约束条件计算炮点和检波点的坐标,然后计算炮检距,再进行校正。这种校正处理的效果也是明显的。但实验表明,对于观测系统误差较大的数据,不宜作坐标计算,只作炮检距校正尚可完成部分校正。处理中要根据数据的性质选取校正方法。

Chek and correction of field observation system,

Erroneous field observation system is often found in seismic data processing, and it causes very bad result. In order to avoid repetitive seismic exploration and improve data processing result, the author compiled the program which uses first break to check and correct fied observation system on IBM 3081 computer. Two correction methods are outlined. The first method only corrects offsets.It includes the following gist: (1)one or several quite accurate first-break time distance curves which are used as standard curves can be plotted by analysing short-refraction data,uphoie time values,reflection data,etc. in an area; (2) a real first-break curve from common-shot gather is compared with the standard first-break time distance curve to determine offsets corresponding to the real first-break curve and to revise the space property of each seismic trace. The processing result of the 3D seismic data coiiected from an area proves the method highly effective. The second method first calculates the coordinates of shotpoints and geophone stations by applying iterative method with the addition of error limiting condition, then estimates offsets and finally makes correction.The correction effect cf this method is also obvious,It is experimentally shown, however, that instead of calculating coordinates, we make offset correction to achieve partial correction for the seismic data in which there is major observation system error.An appropriate correction method should be chosen according to the propetties of seismic data.