Velocity Modeling Technology for Igneous Rocks Based on Full Azimuth Angle Gathers

Summary In the SHB region of the Tarim Basin, the Permian igneous rocks are well-developed. When time-domain or depth-domain seismic imaging is inaccurate, continuous pseudo-structures may appear in the underlying formations beneath igneous rocks, which interfere with the accurate identification of geological structures. This paper proposes a velocity modeling technology for igneous rocks based on full azimuth angle gathers generated by angle-domain migration. Using the FastVel technique for precise picking of shallow residual delays and iterative tomographic inversion ensure the accurate and efficient construction of shallow velocity models. By solving 3D travel-time residuals with the Poisson function, full azimuth tomography inversion with continuously varying azimuths enhances the characterization of igneous rock velocity models compared to conventional multi-azimuth tomography, thereby improving the accuracy of velocity modeling in igneous formations. The processing of actual data demonstrates that this method provides a stable and reliable technique for establishing igneous rock velocity models. Using angle-domain migration, it eliminates the false structures caused by the igneous rocks and restores the true subsurface structural features.