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品质因子Q反映了地下介质对地震波吸收衰减的强弱,是油气检测和储层描述的重要参数,Q值的准确提取,具有重要意义.谱模拟法是提取Q值的一个有效方法,其核心是对地震子波谱进行有效模拟.本文选取合适的函数对地震波谱进行拟合,结合能量衰减规律,发现谱拟合系数可分为三类:与吸收衰减有关;与非频率相关的衰减有关(如扩散、反射透射等);与能量衰减无关.根据与吸收衰减有关的拟合系数可反演品质因子Q值.无噪模型测试表明,拟合系数提取的Q值能较好地反映地层Q值走向.在弱噪情况下,根据三类拟合系数不同的变化规律,首先求取与衰减无关的拟合系数期望值,再对余下的系数进行二次拟合,较好地提高了地层参数的反演精度.模型测试结果证实了该方法的理论可行性.
The quality factor Q reflects the strength of the attenuation and attenuation of seismic waves by underground media and is an important parameter for oil and gas detection and reservoir description.It is of great significance to accurately extract Q. Spectral simulation is an effective method to extract Q value and its core Is to effectively simulate the seismic sub-spectrum.In this paper, we select the appropriate function to fit the seismic wave spectrum, combined with the energy attenuation law, found that the spectral fitting coefficients can be divided into three categories: absorption attenuation related to non-frequency-related attenuation Such as diffusion, reflection and transmission, etc.), And has nothing to do with the energy decay. The quality factor Q can be inversed based on the fitting coefficients related to the absorption attenuation. The noiseless model test shows that the Q value extracted by the fitting coefficient can better reflect the Q In the case of weak noise, according to the different variation rules of the three types of fitting coefficients, the expected values of the fitting coefficients which have nothing to do with the attenuation are first obtained and then the second coefficients of the remaining coefficients are fitted, which improves the formation parameters The accuracy of the inversion.The model test results confirm the theoretical feasibility of the method.