用τ-p变换提取水中声源激发的海底Scholte波

Application of τ-p transformation to extraction of the seabed Scholte wave excited by underwater sound source

水中声源激发的海底地震波场成分复杂,为了将Scholte波从地震波场中分离出来,基于τ-p变换法,先将波场从t-x域变换至τ-p域,利用Scholte波与其他波在该域中的特性差异,提取Scholte波,然后将其反变换回t-x域,从而获得Scholte波。针对τ-p变换过程中固有的假频效应和端点效应,理论分析了各自的产生机理,分别采用限制波慢度和添加时间窗等方法抑制这两种效应。基于高阶交错网格有限差分法,给出了水中脉冲声源激发出的地震波场,并分析了其波动成分及特性,利用上述方法提取地震波场中的Scholte波,仿真结果证明了该方法的有效性。

Seismic wave field excited by underwater sound source is complex.In order to separate Scholte wave from seismic wave field,the original wave field is transformed from t-x domain intoτ-p domain byτ-p transformation,and based on the characteristics of Scholte wave,which are different from those of other waves inτ-p domain,the Scholte wave inτ-p domain is extracted and then inversely transformed back to t-x domain to obtain the Scholte wave.Considering that the inherent false frequency effect and end port effect exist inτ-p transformation,their formation mechanisms are analyzed theoretically,and then these two effects are suppressed by limiting wave slowness and adding time window respectively.The seismic field excited by underwater pulse sound source is given based on the high order staggered grid finite difference method,and then its wave components and characteristics are analyzed.Scholte wave in seismic wave field is extracted by using the above-mentioned method and the simulation results demonstrate the effectiveness of this method.