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Abstract The permeability of interlayer is a key parameter for the tightness evaluation of energy storage caverns constructed in bedded rock salt formations. Thus，the steady gas flow method of permeability tests for typical interlayers of 3 kinds of bedded rock salt areas of China，as well as the analysis of tightness evaluation，has been carried out. The research indicated that：(1) The low permeable properties of the three kinds of typical interlayers are very obvious，with the corresponding permeability range of 10－2–10－5 mD. Due to the large difference of petrophysical properties and geological conditions of interlayers in different areas，the permeability exhibits obviously different with each other，in which the anhydrite mudstone of Pingdingshan has the lowest permeability，but the variance range is the medium；the calcareous mudstone of Jintan has the middle permeability，but the variance range is the maximum；and the saline mudstone of Huai?an has the highest permeability，but the variance range is the minority. (2) The hydrostatic stress states greatly influence the permeability，exhibiting the permeability decreasing as hydrostatic stress increasing. The“compaction criticle pressure”phenomenon is obviously for permeability. When the hydrostatic stress is lower than the transition stress，permeability decreases rapidly(about 1–2 orders). However，while beyond the transition stress the permeability decreases very slow and sustains steady gradually. The fitting relationship of hydrostatic stress versus permeability can be basically expressed by power function： (K is permeability，P is hydrostatic pressure，A and B are fitting parameters). (3) The mechanism of the permeability?s development versus the hydrostatic stress informs that the compressibility of porous interlayer rock. But the compaction effect will become lower and lower even become almost useless while the hydrostatic stress has reached some threshold value；so the permeability will not decrease after then. The test results presents that the permeability of the typical interlayers in bedded salt rock in China is very low so the tightness of storage caverns is basically satisfied.
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Received: 08 April 2013
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2014, Vol. 33 
