Density predictions using V P and V S sonic logs

Colin C. Potter and Robert R. Stewart

ABSTRACT

We use P-wave, V P , and S-wave, V S , velocity logs to predict density, ρ, values. In particular, Gardner's and Lindseth's empirical relationships are used to estimate the coefficients for P-wave and S-wave data and to investigate the relationship between P-wave and S-wave velocities and bulk densities. The data is from four wells in the Blackfoot field and one in the Chin Coulee area of Alberta. The S-wave velocities give a good approximation to Gardner's relationship and we find that ρ=0.37V S 0.22 . The variance or scatter about the best-fit line for predicting densities for both Gardner's and Lindseth's relationship is better for S-wave than P-wave velocities. We suggest there is a relation between S-wave impedance and density and that S-wave velocity can be used to predict density.

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