Abstract:
As hydrocarbon exploration and development advance, target areas exhibit dual complexities:significant surface elevation variations and a research focus shifting towards smaller-scale targets. Vertically Transverse Isotropic (VTI) media are widely applied in prestack migration imaging for complex geological structures. These factors collectively alter wave propagation characteristics, making existing imaging methods inadequate for current high-precision imaging demands. To accurately simulate wavefield propagation in VTI media beneath rugged topography, the boundary-fitted orthogonal grid concept from fluid dynamics was introduced for discretizing VTI media under irregular surfaces. This led to the development of a fully staggered-grid finite-difference simulation algorithm specifically designed for VTI media with topographic relief. Building upon this forward modeling algorithm, the reverse time migration imaging method was enhanced to address the challenges posed by irregular surfaces. Numerical modeling results demonstrate that the proposed method can correctly simulate wave propagation in VTI media with surface topography and achieve high-precision RTM imaging.compared to RTM results based on isotropic assumptions or regular grid discretizations, the imaging outcomes more accurately reflect reflector positions and exhibit fewer imaging artifacts caused by surface topography.