利用零井源距VSP资料进行品质因子反演

Q-factor inversion and calculation using zero-offset VSP data

品质因子Q值是描述地震波衰减的一个重要物理参数,它描述了介质非完全弹性特征,是地层内部本质特征,所以研究和估算Q值在地震勘探中的作用越来越重要。谱比法和质心频移法是现在常用的两种方法。本文详细介绍了两种方法的原理并用无噪声理论模型验证了两种方法的可行性。反演结果显示在无噪声的条件下两种方法都能很好地估算介质的品质因子。通过对含有不同强度噪声的理论数据、全波场理论数据和实际零井源距VSP数据的处理,对两种方法进行了比较。结果表明,质心频移法反演的结果比谱比法更精确、更可信。

Q-factor,which describes the seismic attenuation and the viscoelasticity of the formation,is an important physical parameter depicting seismic wave propagation.Therefore,Q-factor plays a significant role in high resolution seismic prospecting.Spectral ratio method(SRM) and centroid frequency shift(CFS) method are the most popular.In this paper,the concepts of the two methods are introduced first.Then the feasibility is tested by synthetic data.The inversion results show that both the two methods perform well while there is no noise in the inputs.Finally,stability of the two methods is verified by noised synthetic data,synthetic data of full wavefield and field zero-offset VSP data respectively,the results suggest that CFS is more reliable than SRM.