Strategic Storages of Gas in Salt Layers and Creep and Overburden Effects on Volume Loss

The demands for fossil fuels such as natural gas, oil and other hydrocarbon products have been raised in recent decades. Supplying these demands during peak period highlights the importance of storing energy resources during the production. Concerning this issue, storing gas in salt caverns is a suitable method. To describe the mechanical behavior of a typical rock salt due to creep phenomenon, the Multi-mechanism Deformation (MD) creep constitutive model is implemented into the Ansys finite element package using a Fortran routine. To investigate the creep effect on the structural response and volume shrinkage of a salt cavern, an implicit creep analysis is conducted under cyclic loads. The results reveal that applying the overburden pressure leads to a more volume shrinkage of the cavern, while placing overburden layer itself over the salt layer instead of the overburden pressure results in the lower volume shrinkage. Finally, using the contact element between the overburden layer and the salt layer, the volume shrinkage will decrease even further.

Keywords:

Salt cavern , MD creep model , Rock salt , Implicit creep , volume loss , Cyclic loading