Estimated source wavelet‐incorporated reverse‐time migration with a virtual source imaging condition

Many geophysicists perform reverse‐time migration using a variety of artificial sources to obtain the source wavefield. Upon processing the seismic data, however, it is difficult to recover the original phase and amplitude of the source wavelet used for seismic exploration, regardless of the source. We have therefore used several artificial source wavelets such as Ricker or the first derivative Gauss wavelets expressed by well‐known functions. There are some differences between these artificial source wavelets and the original source wavelets, resulting in imperfect migration images. Artificial source wavelets tend to distort the exact location of subsurface reflectors and they create noise around the boundary of the stratum. To solve this problem, we applied the source estimation technique to the reverse‐time migration algorithm. The source estimation technique approximates the source wavelet to the original exploration source wavelet by a deconvolution method. This technique is used in full waveform inversion and provides better inversion results as demonstrated by other studies. To prove the effect of reverse‐time migration with source estimation, we tested this algorithm on the Sigsbee2a model, SEG/EAGE 3D salt model and 3D real field land data. Using the resulting images of these three models, we found that the source estimation technique can yield better migration images. To suppress the artefacts produced in the migration image, we used a wavenumber filter and Laplacian filter on 2D and 3D examples, respectively. Furthermore, we used the pseudo‐Hessian similar to the source illumination to scale the migration image because the virtual source imaging condition was used for reverse‐time migration.