高速层出露区常规地震勘探存在的问题及对策

对比分析了低速近地表和高速近地表对反射波传播的影响.结果表明,当近地表速度为低速时,可以将垂直检波器记录的地震记录近似等同于反射纵波记录,这就是常规地震勘探在低速带区勘探取得成功的原因之一;当近地表速度为高速时,随着界面倾角和入射角的增加,垂直检波器记录的地震记录等效为反射纵波记录的误差增大,这就是存在高速近地表区地震勘探的难点之一.用三分量检波器替换垂直检波器,进而来完整地记录矢量地震波场,这是解决这一困难的根本办法.提出了对高速近地表区进行三分量地震资料处理的方法.

Some problems and strategies for conventional seismic exploration in the high-velocity rock outcropped areas

The conventional seismic exploration by adopting source of compression wave and receiver of single component geophone is unsuitable for high velocity rock outcropped areas such as mountain land,mountain front and tundra areas. The effects of near surface low-velocity layer and near-surface high velocity layer on the propagation of reflection wave were analyzed. The results show that seismic data recorded by vertical geophonc may approximate to the data of reflected compression wave when the near surface velocity of rock in outcropped areas is low,which makes the conventional seismic exploration succeed in these areas. In land areas with high-velocity rock outcrops,the seismic data recorded by vertical geophone deviate from the data of reflected compression wave with the increment of dip angle of strata and incident angle of reflection wave, which results in the difficulties of conventional seismic exploration in the near-surface high velocity rock outcropped areas. The three component geophone can be taken as a receiver to record the vector field of seismic wave instead of the vertical geophone. The processing technologies of the three-component seismic data in the nearsurface high-velocity layer are presented.