Creep closure rate of a shallow salt cavern at Gellenoncourt, France

• We measured creep closure rate of a shallow salt cavern.
• The cavern was left open for 10 months and brine outflow rate was recorded.
• Then the cavern was shut-in and pressure build-up rate was recorded for 6 months.
• The average closure rates inferred from the two tests are quite consistent and slightly slower than 10−5/year.

Cavern creep closure rate was recorded in the SG13–SG14 salt cavern of the Gellenoncourt brine field operated by CSME at Gellenoncourt in Lorraine, France. Cavern compressibility and the evolution of cavern brine temperature first were measured. In this shallow cavern (250-m, or 800-ft, deep), which had been kept idle for 30 years, cavern-brine thermal expansion can be disregarded. To assess cavern closure rate, a 10-month brine-outflow test was performed, followed by a 6-month shut-in test. During the tests, brine outflow or pressure evolution is influenced by atmospheric pressure changes, ground temperature changes and Earth tides. From the average pressure-evolution rate, it can be inferred that the steady-state cavern closure rate is slower than 10−5/year or 3×10−13/s.