Q值提取中的窗口效应

Window effects for quality factor Q estimation

品质因子Q是岩性分析和储层预测的重要属性。大部分的Q值估算方法都需要开窗口提取地震子波谱,不同形状、宽度的窗口对地层衰减信息的影响程度不同。在不同地震子波谱和不同窗口的条件下,通过模型测试,分析了地层Q值的估算误差。测试结果显示,在一般情况下,提取的谱比信息容易受到窗口形状、宽度的影响,由此估算的Q值是不可信的。进一步的测试发现:在衰减窗口条件下,提取的谱比信息在中高频段满足准确的衰减关系,且该特征与窗口形状和宽度无关。据此估计的Q值具有较高的稳定性。

Quality factor Qis an important parameter of hydrocarbon detection and reservoir characterization,which reflects the subsurface seismic wave attenuation.Qestimates are of great significance.Most methods of Qestimation need a certain window to obtain spectrum of seismic wavelets.Windows with different shapes or lengths destroy more or less attenuation.Q estimation errors are analyzed with different source wavelets and different windows through model tests.These tests show that spectral ratio is susceptible to windows shape and lengths,and then destroy the true attenuation relationship,on which unauthentic Qinformation is estimated.Another test gives an interesting conclusion that spectral ratio curve satisfy the accurate attenuation at high frequency when using attenuation windows.This property is almost valid for arbitrary shape and width of window.