速度反转区的表层调查与静校正方法

Near-surface investigation in velocity reversal areas and their static corrections

高精度静校正方法是提高地震资料处理质量的重要环节。在复杂探区,尤其是因火成岩侵入、喷发等原因引起的近地表速度反转区,采用常规小折射调查法难以正确地建立近地表结构。基于面波的频散特性,利用不同波长面波反映近地表不同深度介质的物性参数,且不受速度反转的影响,是速度反转区表层结构调查的一种有效方法。将该方法应用于实际资料并做分析研究后认为:设计满足小折射空间域和时间域的观测方法,利用常规小折射资料进行面波和折射波联合解释,可显著提高速度反转区表层结构调查的精度,为后续处理提供精准的静校正量数据。

High-precision static corrections play an important role in seismic data quality improvement in the processing.It is difficult to accurately establish near-surface structures in complicated terrain areas using the conventional refraction survey method,especially in near-surface velocity reversal areas such as igneous intrusion and eruption areas.Media physical parameters of different depths in near-surface can be reflected by different wavelengths of surface waves,and are not affected by velocity reversal.So based on these surface wave characteristics,we can effectively investigate nearsurface structures in velocity reversal areas.There are two important points when the method is applied in the practice:(1) Geometry design should satisfy the spatial domain and the time domain;(2)Joint interpretation of refraction and surface wave data is needed.Based on our experience,the proposed method can effectively improve the accuracy of near-structures in velocity reversal areas and provide accurate statics.