Straight ray datuming in 3D media - Fast and flexible

Common datuming approaches, like the Kirchhoff or finite difference methods, are rarely applied to 3-D conventional land acquired data because they require reasonable sampling of the sources and receivers, which is not often the case with such data. To combat that, we extend Alkhalifah and Bagiani's (2006) straight ray datuming (SRD) to handle 3-D acquisition geometries. Like in the 2-D case, 3-D SRD is based on straight-rays assumption above and below the datum with Snell's law honored in between. This allows for the application of SRD to common shot gathers in one operation (no need to sort the data to common receivers). Similarly, it can be applied to common receiver gathers directly. This feature allows for more flexibility in acquisition as it requires, unlike in the conventional case, either the sources or receivers to have a complete fine coverage of the area. In addition, SRD does not require detail description of the near surface velocity model, information from refraction static or any other commonly used method to obtain near surface time shifts suffice. In addition, since the operation is a partial migration, it suppresses diffractions generated from inhomogeneities above datum.