Tuesday, May 18, 2004
With Oil being the hot topic
With Bush getting bashed for high oil prices and talk of using the Strategic Petroleum Reserve, I often wondered how this reserve was created. The Dept of Energy has a great web site that details the SPR. Here a link to how the salt domes were created
Salt caverns are carved out of underground salt domes by a process called "solution mining." Essentially, the process involves drilling a well into a salt formation, then injecting massive amounts of fresh water. The water dissolves the salt. In creating the SPR caverns, the dissolved salt was removed as brine and either reinjected into disposal wells or more commonly, piped several miles offshore into the Gulf of Mexico. By carefully controlling the freshwater injection process, salt caverns of very precise dimensions can be created. For every barrel of crude oil to be stored in the SPR's salt caverns, it took 7 barrels of water to create the storage space.
Besides being the lowest cost way to store oil for long periods of time, the use of deep salt caverns is also one of the most environmentally secure. At depths ranging from 2000 to 4000 feet, the salt walls of the storage caverns are "self-healing." The extreme geologic pressures make the salt walls rock hard, and should any cracks develop in the walls, they would be almost instantly closed.
An added benefit of deep salt cavern storage is the natural temperature difference between the top of the caverns and the bottom – a distance of around 2,000 feet. The temperature differential keeps the crude oil continuously circulating in the caverns, maintaining the oil at a consistent quality.
The fact that oil floats on water is the underlying mechanism used to move oil in and out of the SPR caverns. To withdraw crude oil, fresh water is pumped into the bottom of a cavern. The water displaces the crude oil to the surface. After the oil is removed from the SPR caverns, pipelines send it to various terminals and refineries around the nation.
