介质平移初至走时动校正双参数反演

Shifted first-arrival traveltime NMO velocity and η inversion for VTI media

吉林大学地球探测科学与技术学院，吉林长春130026

Zhang Bo,Faculty of Geoexploration Science and Technology,Jilin University,Changchun 130026,China

VTI介质浅层长偏移距动校正一直是地震资料处理的难点之一，常规校正后同相轴不仅出现强烈拉伸，常见的信号交错更会造成同相轴扭
曲，即便采用高精度非双曲线走时公式也无法将精度范围内的信号正确校正。为此，首先采用重建的同一信号周期内各信号点的走时公式，通
过初至点走时将信号整体搬家，消除动校拉伸；然后利用基于初至点走时的双参数反演方法，对传统的相似系数算法公式进行改进。通过对水
平3层VTI介质理论模型试算的结果表明，平移初至整体搬家方法能将长偏移距同相轴无拉伸校平；而初至点双参数反演方法能够大幅提升反演
的精度。

Long-offset NMO correction of shallow layers in vertical transversely isotropic media (VTI) is always one of the difficulties
in seismic data processing. After conventional NMO correction,the seismic events are strongly stretched. Moreover,common
signal interlacing even causes the distortion of seismic events and the signals within the accuracy range cannot be corrected
even by applying high-precision non-hyperbolic traveltime formula. Therefore,shifted first-arrival traveltime NMO velocity
and η inversion for VTI media was proposed. Firstly,after reconstructing the traveltime formula of all signal points in
a signal period,based on the traveltime of first-arrival points,we carry out whole shifting of signals to remove NMO
stretching. Then,shifted first-arrival traveltime NMO velocity and η inversion for VTI media was used to improve the
traditional similarity coefficient formula. Three-layer VTI model testing result indicates that shifted first-arrival
traveltime NMO can correct long-offset events without stretching,and velocity and η inversion at first-arrival points
can largely improve the accuracy of inversion.

10.3969/j.issn.1000-1441.2012.02.002