Physical Property Laboratory Measurements

Wet Bulk Density, Dry Bulk Density, and Porosity

The density determinations made in the physical property laboratory are determined following conventional laboratory procedures. The buoyancy (specific gravity) method is used to determine bulk rock densities, after the samples are saturated with tap water under a vacuum. Subsequently, the samples are dried by oven-baking at 250 degrees F for a minimum of 12 hours.

Dry bulk densities are determined by dry weight divided by the buoyancy- determined volume of each sample. Porosities are calculated from water-saturated weights, dry weights, and the buoyancy-determined volume.

The accuracy of the buoyancy technique of density measurement is better than 0.01 grams per cubic centimeter (10.0 SI units). The results of the laboratory density determinations are reported in grams per cubic centimeter. The SI units conversion is:

        D         =  1000.0 D
                3                    3
         (kg / m )           (gm / cm )

Density measurements can be made on bicylindrical cores, grab samples, or drill cores. Cuttings or sand samples can be measured, but with some loss in accuracy. Very large samples will require coring or breaking prior to the density determination. Moisture saturation under vacuum is required for reliable data.