Elastic Property Scaling Relationships and the Seismic Characterization ofReservoir Flow Units: A Feasibility Approach. Milestone Report, Phase 1, May 1991-May 1992

摘要

The bender log, a new long offset, low frequency sonic log measurement, wascombined with full wave sonic (FWS) log data to provide a unique in-situ data set for measuring velocity dispersion. The FWS data has a nominal frequency range of 10kHz, while the bender log has a nominal frequency range of 1kHz. Repeat surveys, comparisons between a variety of processing methods, and correlations between different data sets were used to provide quality control to the results. There is a consistent dispersion of 0-6% between the slowness curves derived from the FWS and bender logs as a function of depth. The dispersion appears to be higher in the faster sandy units and lower in the slower shaly units. Scattering dispersion, predicted from the distribution of impedance with depth, and intrinsic dispersion, based on lab Q measurements, can explain less than half of the measured dispersion. The authors have applied two different modeling approaches to the interpretation of the dispersion: a scale-dependent equivalent medium approach and a fluid flow mechanistic modeling approach. It appears that one of these approaches could yield the scaling relationship between sonic properties. They have also developed a new method for the measurement of low frequency velocity and attenuation on core samples in the laboratory. This method, called waveform inversion, produces data in the 10-100 kHz frequency range for integration with sonic logging data.