Underground Storage - Salt Caverns

Salt caverns in Ontario are located in the Sarnia and Windsor areas at refineries and petro-chemical plants. The caverns are used to temporarily store hydrocarbons and liquefied petrochemicals and are a critical component of the petrochemical industry in this area. There are 73 active storage caverns in Ontario utilizing 124 wells with a total storage capacity of 3.5 million cubic metres. If the caverns were filled to capacity the contents would have a value in excess of $1.6 billion.


Salt caverns are man-made features constructed within thick beds of salt in the subsurface of Ontario. They are formed by drilling through the overlaying strata down into the salt formation to the calculated cavern location, and washing the cavern to the appropriate size. Salt caverns are formed with a leaching process by injecting a water stream down a well bore in order to "wash" a cavern into the salt. The wall of the completed cavern is insoluble in hydrocarbons and therefore prevents leakages.

Image of a dual entry salt cavern 

 

Dual Entry Salt Cavern
1. Product in/out
2. Brine in/out
3. Product
4. Brine

 

Schematic cross-section through a typical hydrocarbon storage cavern in the Sarnia area. This cavern is "dual entry" meaning there are two wells used to service the cavern. One well (Product in/out) is used for injection of hydrocarbons into the top of the cavern when filling the cavern. To empty the hydrocarbons from the cavern, salt water (brine) is injected using the second well (brine in/out) and the hydrocarbons are displaced to the surface up the first well.