可控震源谐波影响因素分析及对策

Harmonics and its attenuation on vibroseis data

在应用可控震源进行地震资料采集时会产生谐波干扰,谐波畸变包括振幅畸变和相位畸变,这些畸变会降低相关信号的质量。本文从可控震源机械本身、地表耦合以及震源参数三个方面对谐波干扰产生的原因以及分布特征进行了分析。以可控震源振动与大地耦合响应、谐波能量与施工参数关系理论分析为基础,对不同地表耦合程度和不同激发参数产生谐波的大小及对资料的影响程度进行了科学分析和定量计算。在地表耦合上,首次提出了基于"半刚度"地表耦合谐波压制技术,指出增加一次空振扫描可改善可控震源与疏松地表耦合效果。在震源参数上,分析了震源台数、扫描长度、振动次数、扫描宽度等参数对谐波出现时间和振幅能量的影响,建议采用"少台、少次、低驱动、长扫描"激发方式。

Vibroseis sources produce harmonic interference on seismic data acquisition.This interferenceincludes amplitude distortion and phase distortion,which affect data quality.We discuss in this paper harmonics caused from vibrator mechanics,surface coupling,and source parameters,and its distribution characteristics.We analyze quantitatively harmonics of different surface couplings and different source parameters based on the vibration and earth coupling theory and the relationship between harmonics and source parameters.Then we propose a harmonic suppressing approach based on half-stiffness surface coupling.Meanwhile,an additional resonance sweep may improve coupling between vibrator plate and loose surface.We analyze source parameters influence on harmonics including number of units/fleet, number of sweeps,sweep length,sweep frequency band etc.Our proposal offewer units,fewer sweeps,lower drive,and longer sweep length' may be helpful for harmonics attenuation during the data acquisition.