Abstract
Vertical seismic profile (VSP) data have the advantage of higher data quality than surface seismic data. Using VSP data has become a powerful technology to achieve accurate recognition of fine structures. Conventional VSP seismic migration methods mainly use up-going waves (reflection waves) for imaging and often treat down-going waves (multiple waves) as a kind of noise to be suppressed and eliminated. The up-going waves (reflection waves) only provide a narrow subsurface coverage near the receiver well. However, the down-going waves (multiple waves) also carry underground medium information and can provide much wider subsurface illumination than the up-going waves (reflection waves). The imaging quality can be improved by using reflection and multiple waves simultaneously. Therefore, we developed a new joint reverse time migration (JRTM) method to use both the up-going and down-going waves simultaneously based on the mirror principle. The up- and down-going data can be simultaneously placed at the reflection positions and mirror reflection positions as the boundary conditions and initial conditions for wavefield reverse time extrapolation. Some numerical examples from the graben, the modified Marmousi, and the modified HESS models show that the proposed new JRTM method can jointly use and image multiple and reflection waves simultaneously. In addition, the newly proposed JRTM method also has a higher imaging quality than reflection wave migration and multiple wave migration from VSP data in complex structures. High-quality imaging results from our proposed JRTM can be further used to improve the accuracy of subsequent oil and gas reservoir characterization and seismic inversion of VSP data.
NSTL