Method of improving elastic wave reverse time migration offset computation rate and space resolution

Abstract

The invention discloses a method of improving elastic wave reverse time migration offset computation rate and space resolution. During a seismic source wave field forward propagation process, energy of every grid point is calculated, and a moment of maximum energy density and a corresponding wave field value are stored. During a detector wave field reverse time propagation process, the detector wave field having the maximum energy is extracted from every grid point by using an imaging condition, and the stored maximum energy seismic source wave field is used for normalization, and an angle-dependent reflection coefficient imaging profile is acquired. Compared with an excitation time imaging condition, polarity inversion of horizontal components at the two sides of the seismic source is corrected automatically, and during multi-shot superposition, amplitude loss is prevented. Compared with a normalized cross correlation imaging condition, a wave field snapshot is not required to be stored in the seismic source wave field forward propagation process, and a lot of disk space and I / O input output tasks are saved, and therefore calculation efficiency is improved, generated low frequency false appearance is weaker, the imaging capability of the horizontal components is better, and the higher space resolution is provided.

Description

technical field [0001] The invention relates to the field of seismic exploration, in particular to a method for improving the calculation rate and spatial resolution of elastic wave reverse time migration. Background technique [0002] In the field of exploration seismology, seismic migration imaging technology is an effective way to obtain the shape of subsurface structures, among which pre-stack depth domain migration is one of the most accurate imaging methods. Prestack reverse time migration includes wavefield extrapolation and the use of imaging conditions, where imaging conditions are directly related to imaging quality and computational efficiency. At present, the commonly used excitation time imaging conditions do not need to store the source wave field, but only the first arrival or the maximum amplitude wave field is used, and the imaging profile is not a reflection coefficient in dimension, so the image is not clear enough; the cross-correlation imaging condition ...

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Problems solved by technology

At present, the commonly used excitation time imaging conditions do not need to store the source wave field, but only the first arrival or the maximum amplitude wave field is used, and the imaging profile is not a reflection coefficient in dimension, so the image is not clear enough; the cross-correlation imaging condition needs to store the forward TRON snapshot of

Although the cross-correlation imaging conditions have the characteristics of simple implementation and stability, the low-frequency artifacts of the imaging section are serious, and at the same time, the hard disk is required to store the wave field snapshots of the source. When using the imaging conditions, it is necessary to read the wave field snapshots of the source wave field, which seriously reduces the Efficiency of reverse time migration

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