摘要
品质因子是描述地震波在粘弹性介质中传播时信号衰减的重要参数。利用垂直地震剖面(VSP)地震波在频率域中的直达波方程,研究了使用广义逆反演求取粘弹性介质的相速度及品质因子的方法。对理论模型和实测VSP资料的反演表明,通过反演方法估测粘弹性介质的相速度比估测品质因子容易,原因在于相速度反映的是地震波的运动学特征,而品质因子反映地震波的动力学特征,同时也表明品质因子对频率的变化比相速度敏感;在地震波频带范围内,低品质因子的反演结果较接近理论值,而在地层吸收较弱的地层以及小于10Hz的低频段内,品质因子的反演结果都呈现剧烈跳跃变化,与理论值相差较大。
Quality factor (Q-factor) is an important parameter that describes the attenuation of seismic signals inviscoelastic media. Direct wave equation of vertical seismic profile (VSP) in frequency domain was used to devel-op a method for calculation of phase velocity and Q-factor in viscoelastic media under generalized inverse matrixinversion. Inversion of synthetic data and real data showed that the phase velocity is easier to estimate than the Q-factor. The reason is that phase velocity is contained in the arr val times of direct downgoing waves, while Qfactor is mostly contained in the amplitude information of seism c waveforms. The result also indicates that Q-factor is more sensitive to frequency than phase velocity. Low Q-factor values were well recovered in frequencyband, whereas Q-factor behaves irregularly in high Q-value layers or when frequency is lower than 10 Hz.
出处
《勘探地球物理进展》
2004年第5期337-342,共6页
Progress in Exploration Geophysics
