Gas prices are still high, diesel is at a record high, and the reserve has shrunk more than 30% in six months. While the reserve held around 415 million barrels of oil in February, it now holds less than 285 million barrels of oil — lower than it has been since the early 1980s.
These rapid drawdowns of oil threaten the salt caverns’ structure, says Samantha Gross, director of the energy security and climate initiative at the Brookings Institution, a nonpartisan policy think tank. As the reserves get lower and lower, the physical facilities can get degraded, Gross says: " You can damage them by pumping too much out of them."
Its unavoidable by economics and geology.
The oil is stored in impermeable salt caves down in Louisiana and Texas. The hard rock salt and oil do not mix so they act as an environmentally stable storage tank that requires no maintenance and doesn’t leech into the ground. This is vastly cheaper and much much safer for very long term storage of oil.
Problem being the caverns “settle” and are partially supported by the pressure of crude oil within them. As the crude is drawn out of them the salt walls could be damaged if pressure is relieved too quickly and/or not replaced with some other support.
Additionally the pumping infrastructure for crude requires the head pressure of a full tank to hit high flows, and some caverns are emptied first. As caverns empty out there is less head pressure, and requires more pump energy to get it out of a deeper hole. Plus fully emptied caverns will not provide addition inlets for higher flow. This is primarily what drives the “limit of economical recovery” they talk about where flows begin to drop off as the reserve is emptied.
I was under the impression that you’d displace the oil with water, which helps with the pressure but comes with the caveat of leeching into the mineral and deforming the caverns?