Salt Reservoir Mechanics

Salt formations are ideal regions for geologic storage. Their extremely low permeability, ease of mining, and propensity for creep means that they can be relatively quickly developed, used for storage of all types of media (solid, liquid, and gas) and are generally self-sealing to imposed damage in relatively short geologic time frames. However, salt is a highly variable material where even a small percentage (<1%) of water or impurity (ex. polyhalite, anhydrite, clay) can drastically change the response to loading. Therefore, their fluid nature causes problems with maintaining cavern stability, borehole integrity, and bonds to surrounding lithologies. Despite the problems, salt remains one of the preferred storage media for natural gas, oil, and nuclear waste.

Examples of salt mechanics from both the Waste Isolation Pilot Plant (located in the bedded Salado salt formation), and the Strategic Petroleum Reserve (located in several gulf coast salt domes) will be discussed and efforts to mitigate the problems with salt storage while operating effectively in this ideal storage medium will be presented.

Speaker: Mathew Ingraham, Sandia National Labs