This chapter examines the history and evolution of modern seismic migration methods. Modern migration methods evolved from simple geometric concepts to complex wave-equation techniques. The major driving force for such dynamic changes is the overwhelming need to transition from doing calculations using pencils and paper to analog calculators and finally to modern digital computers. This section reviews that process and provides a firm foundation for the geometric concepts that led to the modern era.
It should be noted that modern geophysical mathematical concepts governing wave propagation in complex geologic media have been studied and developed before the current epoch. Many of these theories date back to the early 20th, the 19th, and even, in some cases, the late 18th centuries. While the scientific foundations were definitely available, many early geophysical explorationists tended to ignore them and rely instead on what might be called more ad hoc methodologies. What we use today is the result of a lengthy trial and error stumble urged on by the need to find hydrocarbons hidden in more and more difficult to find traps.
