NIP tomography inversion, a new improved method for velocity model estimation; synthetic data example

Summary

There are varieties of velocity models and velocity estimation methods in seismic data processing, but each has some drawbacks to use specially in complex structures and curved reflectors. NIP tomography inversion method is a new method which works with kinematic wave field attributes. Common-reflectionsurface (CRS) stack provides us with three attributes, among them normal-incidence-point wave curvature R_NIP will be used for the NIP tomography inversion. The method consists of three steps; automatic picking, modelling and inversion. One of the drawbacks of traditional methods is the huge points need to be picked and the difficulty of hand picking. With NIP tomography, we performed automatic picking on coherency section obtained from CRS stack. Picked data were plotted against other parameter and outlier data were omitted from dataset. These outliers are almost related to multiples which could make instability on inversion process. Then the corrected picked points were used for inversion process. In this step, the information velocity was interpolated between picks and trend of velocity changes was cleared. The traveltime for each point was calculated and the final 2D smooth velocity section was modelled. As it was expected, the velocity model performed good improvement in departing velocity variation in small scale and also in complex structures where it does not let conventional methods to differ two velocity values from each other.

Key words::

• Inversion
• NIP Wave
• Automatic Picking
• Ray Tracing
• CRS Stacking.