Correlation Of Elastic Moduli Dynamically Measured By In-Situ And Laboratory Techniques Available to Purchase

Elastic moduli of 15 cores were determined in the laboratory under simulated formation pressure and compared to the elastic moduli as determined from the 3-D velocity log run in the field. The laboratory system used enabled the compressional and shear velocities of the rock samples to be measured sequentially under triaxial pressure. The core samples were from 11 wells from different areas of the country representing a number of differing competent rock types. The ratio of compressional wave velocities measured in the field and the laboratory varied from 0.94 to 1.13 and the ratio of the shear wave velocities measured in-situ and in the laboratory varied from 0.92 to 1.16. The elastic moduli computed from theoretical relations developed for homogeneous, isotropic and elastic materials also indicated good agreement between the two sources of measurementindicating that the 3-D velocity system can provide in-situ measurements with sufficient accuracy to be of practical field use. Young's Modulus and Shear Modulus were related to both the compressional and shear wave velocities. The correlations developed allow both moduli to be predicted from knowledge of either the compressional or shear wave velocity. Finally, a proposed rock classification method is prepared relating Young's Modulus and rock density. Using measurements from 3-D velocity and density logs, sufficient information can be obtained to apply the rock classification system.