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地层品质因子Q反映了地层对地震波吸收衰减的强弱,是油气检测的重要指示因子,准确提取Q值十分重要。本文根据地震子波能量衰减特征,提出基于子波衰减前后能量比的Q值提取方法。该方法是综合利用多点信息估算子波能量,规避了常规Q值方法(如质心频移法)对地震子波谱的假设,适用于任意波谱形状,但对资料的保真度要求较高。VSP正演模型测试发现,在非固有衰减(如几何扩散、反射透射损失等)得到准确补偿的前提下,能比法能较好地反演地层Q值。实际零偏VSP资料应用表明,能比法提取的Q值趋势与谱比法基本一致,具有一定的可信度。
The formation quality factor Q reflects the strength of the seismic wave attenuation attenuation, which is an important indicator of oil and gas detection. It is very important to accurately extract the Q value. In this paper, based on the energy attenuation characteristics of seismic wavelet, the Q value extraction method based on energy ratio before and after wavelet attenuation is proposed. This method uses the multi-point information to estimate the wavelet energy, and avoids the assumption of the seismic sub-spectrum by the conventional Q-value method (such as the centroid frequency shift method). It is suitable for any spectral shape, but requires high fidelity of the data. The VSP forward model test shows that the Q value of formation can be well retrieved than the method under the premise of extrinsic attenuation (such as geometric diffusion, reflection and transmission losses, etc.). The application of the actual zero-offset VSP data shows that the trend of the Q value that can be extracted than the method and the spectral ratio method are basically the same, which has a certain degree of credibility.