兴安岭山地低信噪比地震资料处理技术分析

Processing technique for seismic data with low S/N ratio in Xinanlin Mountains.

大、小兴安岭山地地表大多被火山岩、火山岩风化形成的残余物和腐植土所覆盖,地震资料中普遍存在较强的折射波和多次折射波,资料的信噪比很低;此外,该区低、降速层厚度和速度横向变化剧烈,静校正问题突出,为此,开展了有针对性的处理方法研究。针对山地地表起伏大的特点,采用了浮动基准面方法;针对低、降速层厚度和速度横向变化剧烈的特点,采用了折射静校正和微测井静校正相结合的方法;针对折射波强的特点,采用了t-x域叠前相干压制方法;针对叠加剖面随机噪声严重的特点,采用了f-x域随机噪声衰减方法。实际资料处理表明,采用上述处理手段,提高了资料的信噪比,增强了同相轴的连续性,突出了反射波组特征。

The surface of Daxinanlin Mountains as well as Xiaoxinanlin Mountains is covered with volcanics, volcanoclastic rock and decomposed leaves. Strong refraction and multiple refractions commonly exist in seismic data with a low S/N ratio. In addition, the thickness and velocity of the subweathered zone have great changes laterally, making the static correction very difficult. In order to solve this problem, the following methods were used: 1) the float datum was adopted for radical elevation changes; 2) the combination of the refraction statics and the micro-logging statics was used for the big lateral changes of the thickness and velocity in the subweathered zone and the low velocity layer; 3) the pre-stack coherent noise attenuation in T-X domain was used for strong refraction; 4) the random noise attenuation in F-X domain was applied for the severe random noise of the stack sections. The actual processing shows that the above mentioned processing methods can improve the S/N ratio of the seismic data, enhance the consistency of event, and stress the characteristics of the reflection group.