The Strategic Petroleum Reserve Appears Ready to Evolve

SEATTLE (Oil Monster): The idea of having a strategic petroleum reserve dates back to World War II.

But it wasn't actually created until 1975, after the Arab Oil Embargo created crude oil and gasoline shortages across the nation.

The reserve is composed of four salt cavern complexes with 727 million barrels of storage capacity along the Gulf Coast in Texas and in Louisiana.

The reserve can access interstate pipelines to carry oil to nearly half of the nation's oil refineries, with ships and barges supplying the rest.

Each complex includes caverns that range in size from 6 to 35 million barrels of capacity, with the typical cavern being cylindrical, 200 feet in diameter and 2,000 feet in depth.

At its start, the federal government acquired existing salt caverns owned by private operators to set up a 250 million barrel reserve.

Over time, it built additional caverns by drilling wells into salt formations and using solution mining to create new ones by blasting out the formations using fresh water.

By carefully controlling injections, salt caverns of very precise dimensions were created. It took seven barrels of water to create storage space for one barrel of reserve oil. Dissolved salt either was injected into disposal wells or piped offshore and dumped into the Gulf of Mexico

Besides being the least expensive way to store oil, the use of deep salt caverns also is one of the most environmentally secure, according to the U.S. Department of Energy.

At depths ranging from 2,000 to 4,000 feet, the salt walls of the storage caverns are "self-healing" thanks to extreme geologic pressures. A natural temperature difference between the top and bottoms of caverns keeps the crude oil continuously circulating and at a consistent quality.

Because oil floats on water, the latter is used to move oil in and out of the caverns. To withdraw oil, fresh water is pumped into the bottom of a cavern to push its crude to the surface.

About 60 percent of the oil stored in the reserve is sour, or, has high sulfur content. The remainder is sweet.

 Courtesy: https://newsok.com