Relative density
A pycnometer (from Greek: πυκνός (puknos) meaning "dense"), also called pyknometer or specific gravity bottle, is a device used to determine the density of a liquid. A pycnometer is usually made of glass, with a close-fitting ground glass stopper with a capillary tube through it, so that air bubbles may escape from the apparatus. This device enables a liquid's density to be measured accurately by reference to an appropriate working fluid, such as water or mercury, using an analytical balance.
Density logging
Assuming that the measured bulk density (formula_1) only depends on matrix density (formula_8) and fluid density (formula_9), and that these values are known along the wellbore, porosity (formula_10) can be inferred by the formula