龙门山大山区检波器组合高差认识

Understanding altitude difference of geophone array in Longmen Mountain area

四川龙门山山前带近地表及深部地震地质条件复杂,干扰波异常发育,地震资料信噪比低。大组合基距的检波器接收方式是压制干扰波、提高资料信噪比的有效方法。但龙门山大山区地形起伏剧烈,该方法面临检波器组内高差超出传统认识限制的的问题。为此,对检波器组合高差进行了现场试验和系统分析,认为在龙门山大山区,检波器组合高差更多地由表层降速层速度甚至是高速层速度决定,可以放宽到25 m,从而使得大组合基距检波器接收在该区得以实施,并获得了较好的叠加成像效果。

Because of complicated seismic geological conditions in near surface and deep of front zone of Longmen Mountain, Sichuan, there are anomaly of interference waves and low SNR （ signal to noise ratio）. The geophone receiving mode with big array base distance is an effective method,which can suppress interference waves and improve SNR of seis- mic data. Since there is acute topographic relief in Longment Mountain area, the method is faced with the problem of alti- tude difference of geophone array beyond traditional restriction. So the altitude difference of geophone array was tested and systematically analyzed. The results indicated that the altitude difference of geophone array may be increased to 25 m, which depended on more the velocity of reducing velocity layer and even of high velocity layer in near surface. So the meth- od was applied in the area and obtained good the effect of stack imaging..