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在地震数据的预测反褶积中,假定地层响应是白噪的,而任何非白噪成分都认为是由震源子波和不需要的多次波所引起。我们要指出,对于临界前入射这个假设是不成立的。我们考虑一平面波入射到层状声波半空间的情形,当对半空间中某一层面是确切临界入射时,其下面的地层起到一个近似于刚性底盘的作用。那么半空间的响应是全通的或白噪的。这一结果我们称之谓临界反射理论。如果波在下部半空间是超临界入射,其响应也是白噪的。在常规数据处理中这些超临界的成分用切除的方法去摔。这样,白噪的假设却通常用在了那些假设不成立的数据上。临界前和超临界入射的界限可用于反褶积,并为数据能够分解成平面波创造条件。为推导这一应用,让我们来考虑上部为自由表面的层状半空间表层中点震源的响应。这个响应已被讨论过,是平面波响应的简单重叠,由于震源和接收点处的鬼波以及上部层中的多次反射造成了其复杂性。超临界入射的地层响应对于所有的平面波成份都是白噪的,震源谱可以从中估算出来,这个平面波成份要去掉鬼波和上部屋中多次波的影响。如果震源信号特征已知,这个界限则可以用于分离固有的吸收影响和扩散引起的衰减影响。
In the predicted deconvolution of seismic data, it is assumed that the formation response is white noise, whereas any non-white noise component is thought to be caused by source wavelet and unwanted multiples. We should point out that the assumption of incidence before the threshold is not valid. We consider the case of a plane wave incident on a layered acoustic half-space, which acts as a rigid chassis similar to the one that is critically critical for a given plane in a half-space. Then half-space response is all-pass or white-noise. This result we call the critical reflection theory. If the wave is supercritical in the lower half of the space, its response is also white noise. These supercritical components are dropped by the ablative method during routine data processing. In this way, the assumption of white noise is usually used in those hypotheses are not established data. The boundary between pre-critical and supercritical incident can be used for deconvolution and to create the conditions for the data to be decomposed into plane waves. To derive this application, let us consider the response of a point source in the upper surface of a layered half-space in the free surface. This response has been discussed as a simple overlap of the plane wave responses, which is complicated by ghost waves at the source and reception points and multiple reflections in the upper layer. The formation response to supercritical incident is white noise for all plane wave components from which the source spectra can be estimated. This plane wave component removes the influence of multiple waves in the ghost and upper houses. If the source signal signature is known, this limit can be used to separate the inherent absorption effects from the attenuation effects caused by diffusion.