Pragmatic migration: A method for interpreting a grid of 2-D migrated seismic data

Abstract

Areas of complex faulting cannot be interpreted satisfactorily using stacked sections, so in the absence of a full 3-D survey, it is necessary to interpret the migrated stacks. However, this leads to the well‐known problem of data misties at intersections: migration changes the reflection time on dip lines but not on strike lines; therefore, if stacks tie, migrations won’t. The traditional responses to this have been: ignore strike lines where misties occur, guess at the picks and contour through the misties, or tie the data around loops, introducing arbitrary faulting where “necessary.” There is a fourth approach, described here, which results in accurately tied loops in virtually all circumstances. It has the added merit of leading to a finally contoured map which, on the average, is 90 percent correctly migrated and which can be extended to give a fully migrated map. This is the method which I term “pragmatic migration.”