The storage of hydrocarbons is a very important component of the Ontario oil and natural gas industry. Most storage comes in the form of salt caverns, natural aquifers converted to natural gas storage reservoirs, and is in depleted natural gas or oil fields
Salt caverns are 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.
Depleted natural gas or oil fields are converted from production to storage duty takes advantage of existing wells, gathering systems, and pipeline connections. Depleted oil and natural gas reservoirs are the most commonly used underground storage sites because of their wide availability.
In some areas natural aquifers have been converted to natural gas storage reservoirs. An aquifer is suitable for natural gas storage if the water bearing sedimentary rock formation is overlaid with an impermeable cap rock. While the geology of aquifers is similar to depleted production fields, their use in gas storage usually requires more base (cushion) gas and greater monitoring of withdrawal and injection performance. Deliverability rates may be enhanced by the presence of an active water drive.
Salt caverns 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.