初至静校正的一种方法

MAKING STATIC CORRECTIONS WITH FIRST ARRIVAL

地矿部石油物探研究所

本文提出了一种表层均匀化静校正的原理和方法。根据地震记录上的初至即可实现上述的静校正而无需进行专门的低速带测定.根据常规的共中心点资料,沿测线对野外地形的高程和由低速带的速度变化所造成的时差进行统计,所得资料即可以足够高的精度估算出测线上各点的静校正值。当地形起伏较大和校正后的低速层面具有较大的倾斜时,还需再进行分层,并进行第二次校正。在许多较复杂的情况下这种方法可以使校正工作大大得到简化,此时基准点、校正面、野外工作方法和测地资料并不强调。本方法对表层速度值并不需要有精确的了解,基本上是直接利用记录初至时间的一种具有广泛适用性和经济有效的方法。通过正、反演模型计算结果,验证了本方法的可行性。

In this paper, the axiom and technique of making static corrections for near surface consistency were described and presented. By using the first arrival of the seismic record, the correction could be made without the data specially measured for the low velocity layer. In line with the conventional CMP data, the values of the static correction of each point on the profile could be estimated with sufficient accuracy by dint of the statistical material of the moveouts caused by the relief of the terrian and the variation of low velocity layers. It is necessary to re-divide the layers and make another correction once again when the relief of the trrian is rather severe and the low velocity interface has a big slant slope. In many problem areas, the technique recommended could make the correction more simple even in the case of lacking the base-point, the reference plane as well as the data of geodetic survey.As for the method mentioned above, it is unnecessary to have the accurate nearsurface velocities, hence, it is in essence such a method of directly using the first arrival time and has the merits of widely applicable, economic as well as highly efficiency.