Geological Information Of Wave Attenuation And Velocity Dispersion Extracted From Vsp And Well Logs Data

Anelastic attenuation of propagating seismic waves in a geological medium is caused by internal friction between rock particles during the process of the transfer of energy from the wave to the medium. Velocity dispersion can be correlated with anelastic attenuation, and this information is required for seismic data processing and interpretation. In this paper, the Quality Factor (Q) was estimated from zero offset VSP data using a centroid frequency shift method. Velocity dispersion for both Vp and Vs by was estimated by comparing VSP (Interval P & S velocities) versus sonic data in Well A. The VSP survey was conducted using three component geophones and an air gun array as a source. Well A is a deviated well with maximum inclination of 27 degrees. The analysis shows that frequency dependence of Q is reduced with depth, and changes in the Q gradients and velocity dispersion are consistent with sequence/ lithology boundaries, fluid type and pressure differences.