The Kobe Porosimeter and the Oil Well Research Porosimeter

Reasons are given for using a Boyle's-law porosimeter in conducting coreanalysis for either routine or research purposes. Among other things, it ispointed out that such a porosimeter permits the measurement of all basicproperties on the same sample, thereby eliminating the sources of errorinherent in the use of adjacent samples. References are made to investigationsof gas adsorption on various porous materials, to show that the use of heliumin Boyle's-law porosimeters reduces to negligible proportions the error due tothe adsorption or desorption of the operating gas. Two Boyle's-law instruments are described, which permit accurate and rapidmeasurements of porosity. Schematic sketches and explanations are included, along with derivations of equations required in performing precisedeterminations. Summaries of data obtained during calibration are tabulated and analyses of thedata are presented as indications of the precision and accuracy of each device. Comparisons are also shown for measurements made with each of the instrumentson the same test pieces and cores. Introduction An accurate porosimeter, operating on the principle of Boyle's law, is ofconsiderable value in the analysis of cores for either routine or researchpurposes. This is due primarily to the fact that the measurement of porositywith such an instrument leaves the sample free of' contamination by anyliquid. When used in conjunction with an extraction apparatus for determining oil andwater saturations, a Boyle's-law porosimeter permits the measurement of allbasic properties on the same sample. This eliminates the sources of errorinherent in the use of adjacent samples, or the necessity of determiningporosity after all other properties have been obtained. Large errors may result from combining measurements made on adjacent samples inorder to obtain a single property. This type of error is definitely involvedwhen oil and water are measured with one sample and the pore volume is measuredwith an adjacent one. Furthermore, the source of error would be present to someextent, even if the analyst could choose the samples so they were trulyadjacent from a geological standpoint. T.P. 2953