Porosity analysis has two main parameters of interest that are typically used in further applications; pore volume (VP) and porosity (φ). Pore ​​volume is the actual volume of pores within the sample, and porosity is the ratio of void space to total volume. From the American Petroleum Institute (API) Recommendation Practice for Core Analysis (1998), these values ​​can be calculated using equations 1 and 2 below using the mass volume (VB), which is the total volume of the sample, and the volume of the grains (VG), which is the effective volume of the sample mass. V_P=V_B-V_G (1) φ=(V_B-V_G )/V_B (2) The two parameters can be related using equations 3 and 4 following. φ=V_P/(V_P+V_G) (3) φ=V_P/V_B (4)The pore volume, bulk volume and grain volume can be determined experimentally using various methods, the most common of which are listed in following table from API Recommended Practice for Core Analysis (1998). Table 1 - Methods for Determining Mass Volume, Grains and Pores Mass Volume Archimedean buoyancy methods, as outlined by API (1998), apply Archimedes' principle to determine the mass volume of a sample by fluid displacement ( most commonly mercury). The amount of mercury displaced can be related to the overall volume by the following equation.V_B=(Mass of mercury displaced)/(Density of mercury) (5)A typical setup for this measurement method using mercury as the displaced fluid, shown in Figure X below uses a container filled with mercury resting on a zeroed electronic scale. A sample is then lowered and forced into the mercury until it is completely submerged. Due to Archimedes' principle, which states that the buoyant force is equal to the weight of the displaced fluid, the weight changed on the scale is directly related to the... center of the paper...) (6 )Where:P1 = volumetric pressure initial absolute reference pressure.P2 = absolute expansion pressure.Pa = absolute atmospheric pressure initially in the sample.Z1 = gas deviation factor at P1 and T1.Z2 = gas deviation factor at P2 and T2.Za = gas deviation factor at Pa and T1.T1r = absolute temperature of the reference volume at P1.T1 = absolute temperature of the sample pore volume at Pa.T2 = absolute temperature of the reference volume and the sample after P2 has stabilized.Vr = reference chamber volume.VP = sample pore volume.Vv = valve displacement volumeVd = dead volumeThe valve displacement volume, dead volume and reference chamber volume are all determined during the calibration process before testing . In an isothermal system the equation can be further simplified:V_P=(V_r ((P_1 Z_2)/(P_2 Z_1 )-1)-V_v)/(1-(P_a Z_2)/(P_2 Z_a ))-V_d (7 )High pressure porosity challenges us