Abstract
Due to the large-scale and strong perturbation features of salt bodies, it is very difficult to complete a good salt building with the conventional full waveform inversion (FWI) method without low-frequency data and prior information. The direct envelope inversion (DEI) method is quite effective for salt building when seismic data lack low-frequency information. However, in the current DEI studies, the calculation of the envelope field, which needs a nonlinear envelope operator, does not consider the influences of wavefield overlapping, and the inversion quality of subsalt areas needs further improvements. In this paper, we analyze the effects of wavefield overlapping on envelope field calculation and propose a new envelope field calculation method based on wavefield decomposition. Then, we propose a wavefield decomposition-based direct envelope inversion (WDDEI) method, in which the gradient is calculated using the new envelope field. To improve the inversion quality of subsalt structures, we propose a structure-guided perturbation decomposition method, which can separate the strong scattering salt information from the DEI results with the help of reverse time migration images. Finally, numerical tests are conducted on a modified SEG/EAGE salt model to demonstrate the effectiveness and the antinoise performance of the proposed method.
Highlights
Salt domes have been considered as good caprocks of oil and gas resources; high-precision salt building is attracting more and more attention in the field of exploration geophysics
It is difficult for conventional Full waveform inversion (FWI) to conduct good salt building in real cases because the large-scale and strong perturbation features of the salt body require abundant low-frequency data, which are always difficult to acquire
To improve the inversion of subsalt structures, we propose a structure-guided perturbation decomposition method, which can separate the strong scattering salt information from the direct envelope inversion (DEI) results with the help of reverse time migration (RTM) images
Summary
Salt domes have been considered as good caprocks of oil and gas resources; high-precision salt building is attracting more and more attention in the field of exploration geophysics. To reconstruct the salt velocity model in the absence of low-frequency data, many researchers modify the algorithm of conventional FWI and propose some promising methods. The direct envelope inversion (DEI) method has been proven to be a quite effective method for salt building in the case of a lack of low-frequency information [13,14]. To improve the inversion quality of salt bodies and the subsalt structures, the reflection DEI method has been proposed [18]. We propose a wavefield decomposition-based direct envelope inversion (WDDEI) method, in which the gradient is calculated using the new envelope field. To improve the inversion of subsalt structures, we propose a structure-guided perturbation decomposition method, which can separate the strong scattering salt information from the DEI results with the help of reverse time migration (RTM) images.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
