In this lab you will have to determine the porosity of your rock sample using the helium porosimeter shown on page 4. This device contains two cells, the sample cell and the expansion cell. Three valves, V1, V2 and V3 control the gas flow throughout the system; V1 connects the sample cell to the helium tank, V2 allows gas out of the system and V3 controls the flow between the sample cell and the expansion cell. A pressure sensor provides measurements of the gas pressure inside the sample cell. The pressure readings are displayed on a multimeter connected to the sensor under the form of voltage.
The recovery of the porosity using the helium porosimeter requires the application of Boyle's law. This law states that, under conditions of fixed gas quantity and constant temperature, the product of the pressure and volume stay constant. Boyle's law is expressed as follows:
