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

(1.中国地质大学地下信息技术与仪器教育部重点实验室,北京100083;2.大庆石油管理局物探研究所,黑龙江大庆163357)

Geo-detection Laboratory, Ministry of Education, China University of Geosciences, Beijing 100083, China

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.