Knowing the envelope and skeletal volumes of a core sample allows the total pore volume and percent porosity of the sample to be determined.

Since a core typically is a right circular cylinder, simple physical measurements of its diameter and length allow the envelope volume to be calculated.

A gas displacement pycnometer is a low-cost, non-destructive, non-hazardous technique for measuring the skeletal volume. The Porosimeter is a simple instrument using Boyle’s law for measurement of Grain Density. The system undergoes a 5 point Calibration routine against a set of calibrated discs.

A 4^th degree polynomial equation is used to fit the data to generate the reference volume and the system dead volume.

The equation of the line is used to calculate the unknown grain volumes

Grain Density = Sample Weight / Measured Grain Volume

Knowing the Grain Volume, porosity can be calculated using various methods

Porosity = (Dimensional Bulk Volume – Measured Grain Volume) / Dimensional Bulk Volume