Processing in time and depth domains
Processing in depth domain becomes interpretive. It allows analyzing data via taking a priori information about depths of structures into account. Therefore processor can operate with depth images since the very beginning.
A priori information usage and geological assumptions involvement are obviously “must-have” components of successful processing of seismic data. Geological information so needed during processing and interpretation have some specific features:
- Detailed information about velocities obtained from wells is available only for few points. Even if we have some information extracted from wells it’s usually not enough to create accurate depth-velocity model. Especially as soon as seismic researches are mostly dedicated to the geological boundaries behavior and velocity variations for the whole area between and around wells;
- Average velocity, obtained from well-log data can be different from parameter VRMS on the same point of area even for quite simple geological situations. In cases of complex structures, when you deal with salt bodies, strongly dislocated tectonics, the CMP travel time curve configuration may be so much different from hyperbolic, that VRMS usage became totally incorrect;
- Geological assumptions are usually created by geologists not in terms of traditional geophysical parameters that are used in processing.
All features described above require depth imaging to be not only final processing stage, but necessary tool for almost all processing stages.
Prime allows you to extract information from both time and depth imaging at the same time. It brings you some powerful processing benefits:
- simple and geologically interpretable picking of horizons in depth domain, among other reasons, preceding application of a multichannel migration operator;
- simplification of the shape of the moveout;
- convenient account for the a priori information about depth and velocity of the reflecting boundaries;
- automatic control of flattering of the moveout;
- possibility of application of the algorithms to the data on relief with no need of wavefield redatuming to a horizontal level. In this case the traveltimes are non-hyperbolic and cannot be simplified in the time domain (in contrast to the depth domain);
- the wavefields obtained with the correlation in the depth domain allow subsequent picking (correlation in the time domain), This is important for the static shifts correction.