Patterns of progress - subsalt imaging

The ability to image complex structures has evolved fairly recently, largely driven by the discovery of reservoir-quality structures lying beneath salts and basalts or in complex carbonates. Facilitated by prestack depth migration (PSDM) techniques, geophysicists mapped subsalt sediments in the deep waters of the GoM in the early 1990s. When the first discovery well was drilled beneath the salt, the conventional wisdom of more than 70 years went out the window.