  Storage of natural gas in salt caverns had been developed mainly for seasonal
storage, resulting in a small number of yearly pressure cycles and moderate
gas-production rates. The needs of energy traders are changing towards more
aggressive operational modes. The "high-frequency cycling" operation of salt
caverns raises questions concerning the effects of frequently repeated and
intense mechanical and thermal loading. These questions concern the
constitutive creep laws for salt, laboratory test procedures, criteria to be
used at the design stage to provide operability, and the long-term integrity of
the underground salt caverns.
