Study On The Characteristics Of Permeability And Tightness Of Layered Rock Salt Storage

In recent years strategic energy reserves become very important with the decreasing of energy, and rock salt cavern underground becomes many countries' choice due to excellent properties of rock salt. Most of our country's rock salt deposits are very thin, and the thickness of single-layer is small, with uneven impurities in it, which increases the difficulty in constructing energy storage and nuclear waste repository in the rock salt deposit in China. Not only the permeability and tightness of the rock salt body, the convergence of the cavity and the stability of rock salt, but also the effect of the nature of existence of the interlayers must be considered.In this paper the results of the study on rock salt and layered rock salt in the past were discussed, the existing problems of permeability and tightness of rock salt were considered, and the research in the following aspects was carried out:1. The creep characteristics of the rock salt, especially the bedded rock salt were summarized through uniaxial and triaxial test, the creep damage was further discussed.2. Using the software FLAC3D, numerical simulations on the creep properties of rock salt with mudstone interlayers under constent inner pressure were carried out and the effect on permeability and tightness was analyzed with different parameters of both soft and hard mudstone interbeds.3. In order to determine the convergence law and creep damage of rock salt cavity under different operation conditions, the internal pressure was changed and cycle internal pressure was simulated, and the permeability and tightness of the caverty in bedded rock salt were deeply evaluated.The numerical studies show that the destroying forms of interlayers with different characteristics are different during long-term creep.The destruction of hard parts begins from the rock salt and the failure of soft one is relatively complicated,there may be compressed and multiple-shear damage.The changes of working pressure have effect on tightness and permeability ,overall,the high pressure in a reasonable scope is more advantageous to the stability of the cavity.