Prestack depth imaging/migration transforms the seismic data into an image, which reveals the subsurface geology. The imaging technology has made rapid progress in the past decade. Especially the wave propagation based migrations are considered to be the methods of choice for imaging complex structures. In the meantime, we have seen the demand for imaging technology to move from its heuristic roots to mathematically sound techniques.
Traditionally, One-way Wave Equation Migration (OWEM) was considered as a rough and intuitive inversion method. Based on Zhang (1994) and Bleistein (1987), we reformulated one-way wave equations to provide accurate amplitude as well as traveltime. We developed true amplitude OWEM theory in both shot domain and reflection angle domain. Especially, we found that the angle domain true amplitude migration is a stable inversion algorithm. Therefore, we have built OWEM on a solid theoretical base.
Later, we generalized our theory to Reverse Time Migration (RTM) and developed a 3D true amplitude migration theory in reflection/azimuth angle domain. Anisotropy and visco-acoustic absorption can also be incorporated in a migration to calibrate the image.
We will use many real data examples to show how the imaging technology evolutions have greatly improved our capability to image the interior of the earth.