Novel apparatus to measure the low-permeability and porosity in tight gas reservoir

초록

This study proposes a new apparatus which can simultaneously measure the physical properties such as low-permeability and porosity in a tight gas reservoir. The apparatus can also measure bi-directional permeability efficiently. The measurement of bi-directional permeability is designed in consideration of flow direction which can cause different results by heterogeneity. Using the apparatus, the experiments have been carried out to measure the low-permeability and porosity of three tight sand core samples which are from Gyeongsang sedimentary basin in Korea. As the results, the porosity ranges from 5.63% to 11% and the permeability measured in forward and reverse direction is 0.0004 md and 0.0005 md for TS-1, 0.0007 md and 0.0011 md for TS-2, and 0.0062 md and 0.007 md for TS-3, respectively. To investigate the effect of geological characteristics inside core sample on rock properties, X-ray scan of the core samples was taken by Microfocus X-ray CT. Obviously, the value of permeability and porosity are subject to geological features such as micro-crack. This means that the micro-crack plays an important factor in terms of permeability variation by its direction and length in a tight gas reservoir. For verification of measurement accuracy, regression analysis was carried out using the dimensionless pseudo-pressure between the measured data and analytical model. As the results, it is shown that both are approximately equal in terms of permeability and porosity. (C) 2016 Elsevier B.V. All rights reserved.

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