Travel time is perhaps one of the most important seismic parameter. It can be used to estimate properties of the subsurface. Velocity is one of these properties, and its importance has been increasing because it is the unique element that can convert time into depth. Seismic exploration has been evolving from time studies to depth studies because they map actual geology. Velocities can be also used to estimate petrophysical properties.
My goal is to find interval velocities from seismic data. Seismic velocities were considered important only as a parameter for stacking seismic data (one of the most important computer process in the prospecting industry Claerbout (1985)) or for converting structure maps from time to depth.
There are many methods of building an accurate velocity model; one of these
uses maximum stacking power. The velocity model built in this way
yields it to one
kind of seismic velocity: the root mean square velocity (
). Interval
velocity is sometimes derived from rms velocity. Processes such as
prestack depth migration are very sensitive to errors in the velocity model.
Because of this, prestack depth migration is also used as a tool to
estimate an interval velocity models Sava (2000).
Methodologies such as Residual Curvature Analysis Al-Yahya (1989) and
Depth Focusing Analysis Faye and Jeannot (1986)
are different ways of building a velocity model.
Tomography is another technique of estimating velocities from seismic
data Clapp and Biondi (2000).
We can note that there are many ways of estimating velocities from seismic data, and it is not easy to find a solution to improve such estimation.
In the following pages, I will introduce a method that incorporates well information and seismic data; this method can help us to improve the velocity model. It is not a new approach Brown (1998); Clapp et al. (1997), but I review those works and provide a basis on which we can build our ideas about the velocity model building process.